Communication device, communication method, and communication system

Abstract

This communication device comprises: a transmission control unit that transmits a second initial access signal configured such that the amount of resources required for transmission of information constituting an initial access signal, which is for notifying a terminal device of information pertaining to initial access to a wireless network, is less than that of a first initial access signal configured from a synchronization signal and a notification signal; and a reception control unit that receives an uplink signal for initial access.

Description

Communication device, communication method, and communication system

[0001] This disclosure relates to communication devices, communication methods, and communication systems.

[0002] To achieve high-performance wireless communication, the development of wireless communication technologies is being actively pursued. For example, in 5G, various studies are being conducted to realize highly reliable and low-latency communications (URLLC).

[0003] 3GPP, RP-242354, “Revised WID: Enhancements of network energy savings for NR,” 3GPP TSG RAN Meeting #105, September 2024

[0004] However, a communication method that exhibits high communication performance in one scenario may not exhibit high communication performance in other scenarios (e.g., high resource utilization efficiency, large capacity, high speed, low latency, high reliability, high density, many simultaneous connections, low power consumption, or low processing load). For example, in networks operated in environments with a small number of connected terminals (or in environments with low connection frequency) in order to ensure network area coverage, a power-efficient communication method (a low-power communication method) is required. However, 5G communication methods that prioritize low latency may not be able to achieve high power efficiency.

[0005] Therefore, this disclosure proposes a communication device, a communication method, and a communication system capable of achieving high communication performance.

[0006] It should be noted that the above-mentioned problems or objectives are merely one of several problems or objectives that can be solved or achieved by the multiple embodiments disclosed herein.

[0007] To solve the above problems, one form of communication device according to the present disclosure includes a transmission control unit that transmits a second initial access signal, the amount of resources required to transmit information constituting an initial access signal for informing a terminal device of information regarding initial access to a wireless network is less than that required for transmitting a first initial access signal consisting of a synchronization signal and a broadcast signal; and a reception control unit that receives an uplink signal for initial access.

[0008] This is a diagram illustrating the outline of an embodiment. This is a diagram illustrating an example of the configuration of a communication system according to an embodiment. This is a diagram illustrating the configuration of a management device according to an embodiment. This is a diagram illustrating the configuration of a base station according to an embodiment. This is a diagram illustrating the configuration of a relay station according to an embodiment. This is a diagram illustrating the configuration of a terminal device according to an embodiment. This is a diagram illustrating an example of a communication system according to an embodiment. This is a diagram illustrating standalone operation. This is a diagram illustrating standalone operation. This is a diagram illustrating power concentration technology to a specific point (point forming). This is a diagram illustrating an example of point forming with a single antenna having many antenna elements. This is a diagram illustrating the near-field and far-field. This is a diagram illustrating the Fraunhofer distance which is the boundary between the near-field and the far-field. This is a diagram illustrating an example of point forming in a distributed antenna environment. This is a sequence diagram showing an example of initial access processing. This is a diagram illustrating a collision-based random access procedure. This is a diagram illustrating a non-collision-based random access procedure. This is a diagram illustrating a two-step random access procedure. This is a diagram illustrating the outline of the operation of a communication system. This is a diagram illustrating the signal configuration of a second initial access signal. This is a diagram illustrating the signal configuration of a second initial access signal. This is a diagram illustrating the signal configuration of a second initial access signal. This is a diagram illustrating the signal configuration of a second initial access signal. This is a diagram illustrating an example of resource allocation for an initial access signal. This is a diagram illustrating another example of resource allocation for an initial access signal. This is a sequence diagram showing the communication process according to the first embodiment. This is a sequence diagram showing the communication process according to the second embodiment. This is a sequence diagram showing the communication process according to the third embodiment. This is a sequence diagram showing the communication process according to the fourth embodiment.

[0009] The embodiments of this disclosure will be described in detail below with reference to the drawings. In the following embodiments, the same parts will be denoted by the same reference numerals to avoid redundant descriptions.

[0010] Furthermore, in this specification, the expression "at least one of" accompanied by an enumeration of elements is understood to mean that the enumerated elements are the choices. For example, "at least one of A, B, and C" means "(A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C)." "at least one of A, B, or C" and "at least one of A, B, and / or C" are similar to "at least one of A, B, and C." Here, A, B, and C are all arbitrary expressions (e.g., word, phrase, clause, term, or item).

[0011] Furthermore, in this specification and drawings, multiple components having substantially the same functional configuration may be distinguished by adding different numbers after the same reference numeral. For example, multiple components having substantially the same functional configuration may be distinguished as communication point P as needed. １ , P ２ , and P ３ They are distinguished in this way. However, if there is no need to particularly distinguish each of multiple components that have substantially the same functional configuration, only the same code is assigned. For example, communication point P １ , P ２ , and P ３ When there is no particular need to distinguish between them, they are simply referred to as communication point P.

[0012] The one or more embodiments (including examples and modifications) described below can each be implemented independently. On the other hand, at least some of the embodiments described below may be implemented in appropriate combination with at least some of the other embodiments. These embodiments may contain novel features that differ from each other. Therefore, these embodiments may contribute to solving different objectives or problems and may produce different effects.

[0013] This disclosure will be explained in the following order of items: 1. Overview 1-1. Background and Issues 1-2. Overview of Solutions 2. Configuration of the Communication System 2-1. Example of Management Device Configuration 2-2. Example of Base Station Configuration 2-3. Example of Relay Station Configuration 2-4. Example of Terminal Device Configuration 3. Underlying Technologies 3-1. Communication Points 3-1-1. Definition of Communication Points 3-1-2. Specific Examples of Communication Systems 3-1-3. Point Forming 3-2. Initial Access Control 3-2-1. Basic Procedure 3-2-2. Random Access Procedure 3-2-3. Random Access Procedure for NR 3-2-4. Initial Access Control in Self-Free Communication 3-3. Supplementary Information 4. Operation of the Communication System 4-1. Explanation of Terms 4-2. Overview of Operation 4-2-1. Overview of Communication Point Operation 4-2-2. Overview of Terminal Device Operation 4-3. 4-3-1. Second Initial Access Signal with a Novel Signal Configuration 4-3-2. Second Initial Access Signal with a Signal Configuration Corresponding to the Conventional Signal Configuration 4-3-3. Example of Resource Allocation 4-4. First Uplink Signal 4-5. Transmission of the Second Initial Access Signal 4-5-1. Transmission Conditions 4-5-2. Environmental Conditions / Use Cases 4-5-3. Configuration of the Second Initial Access Signal 4-5-4. Indication for Transmission of the Second Initial Access Signal 4-6. Communication Processing 4-6-1. First Embodiment 4-6-2. Second Embodiment 4-6-3. Third Embodiment 4-6-4. Fourth Embodiment 5. Modification 6. Conclusion

[0014] <<1. Overview>> First, the overview of this embodiment will be described.

[0015] <1-1. Background and Issues> Technologies related to wireless communication such as cellular communication have been actively developed. Currently, in 3GPP (registered trademark), discussions on B5G (Beyond 5G) and 6G (6th Generation Mobile Communication System) have been started in parallel with the formulation of 5G specifications.

[0016] Conventionally, cellular communication has been controlled in units of the communication range (communication coverage) of one base station (including a TRP (Transmission and Reception Point)), which is called a cell. However, in B5G and 6G, in addition to millimeter waves, system operation in high-frequency bands such as terahertz waves is expected. Communication using high-frequency bands has a shorter propagation distance than communication using low-frequency bands. Therefore, in B5G and 6G, it is assumed that the communication range (communication coverage) of the base station will be smaller than before.

[0017] Also, in future wireless communication, it is expected that communication nodes will diversify. For example, in 5G, in addition to the base station, an overhanging antenna called a TRP is assumed to be used as a communication node. Furthermore, in 5G, an IAB (Integrated Access and Backhaul) node (that is, a base station relay) is assumed to be used as a communication node. Also, in 5G, an NTN (Non-Terrestrial Network) node (for example, a communication satellite) is assumed to be used as a communication node.

[0018] In B5G and 6G, further diversification of communication nodes is expected to be pursued with the aim of supporting high frequency bands and / or reducing CAPEX / OPEX. For example, in B5G and 6G, smart repeaters (e.g., RIS (Reconfigurable Intelligent Surface)) are expected to be used as communication nodes. In addition, terminal-to-terminal relays are also expected to be used in B5G and 6G. Conventional communication nodes were either fully controllable communication nodes (e.g., base stations and / or IAB nodes) or communication nodes that could not be controlled at all (e.g., RF (Radio Frequency) repeaters). However, in the future, it is expected that communication nodes with controllable parameters will also be used.

[0019] To deploy a communication area across a wide area using communication nodes with narrowed communication coverage, an extremely large number of communication nodes are required. Therefore, it is expected that conventional cell design will become very difficult. Furthermore, the diversification of communication nodes will also increase the difficulty of cell design. For this reason, it is expected that cell-free networks will be introduced as a basic function in B5G and 6G. A cell-free network is a wireless network that eliminates cell boundaries in a conventional cell configuration (cellular network) centered on a base station. A cell-free network realizes an optimal communication environment that does not depend on the positional relationship between the user and the base station. The realization of a cell-free network will enable more efficient network operation. In addition, the realization of a cell-free network will enable the efficient provision of information on a user-by-user basis.

[0020] In a self - free network, cooperation between base stations and the like becomes a topic of discussion. As described above, in an environment where there are various types and / or frequencies of communication nodes, an increase in power consumption due to an increase in the number of communication nodes is expected. Therefore, the demand for operating each communication node with lower power consumption is assumed to increase. In recent years, regarding the area coverage of wireless communication networks, while the population coverage rate is being improved, the area coverage rate is low, which is an issue. In order to solve this issue, it is expected that the coverage of macro cells will be further expanded in the future.

[0021] In mountainous areas and / or rural areas, etc., it is assumed that a wireless communication network will be operated in an environment where the number of connected terminals is small (or the connection frequency is low). In a network operated in an environment where the number of connected terminals is small (or the connection frequency is low), a communication method with high power efficiency is required. However, in 5G, since emphasis is placed on low latency, the amount of information included in the initial access signals (synchronization signals and / or notification information) transmitted periodically is large. As a result, when the 5G communication method is directly applied to a wireless communication network operated in the above environment, it may not be possible to achieve high power efficiency.

[0022] <1 - 2. Outline of the solution means> Therefore, in this embodiment, the above problems are solved as follows.

[0023] FIG. 1 is a diagram for explaining the outline of this embodiment. In the example of FIG. 1, a plurality of communication points (communication points P shown in FIG. 1 １１ ~P １Ｎ ) are arranged. N is an arbitrary integer of 1 or more. The communication point is, for example, a communication node (such as a base station, a relay station, or an antenna) that a terminal device (UE shown in FIG. 1) can access. The communication point may be a base station (BS shown in FIG. 1). The communication points P １１ ~P １Ｎ may each be a communication point controllable by a base station (for example, an antenna provided by a base station). Also, a cluster composed of a plurality of communication points may be regarded as one communication point. For example, the communication points P shown in FIG. 1 １１ ~P１Ｎ A cluster composed of (communication point P shown in Figure 1) １ ) may be considered as a single communication point.

[0024] As mentioned above, 5G emphasizes low latency. Therefore, the initial access signal (synchronization signal and / or broadcast information) transmitted periodically from the base station to the terminal device contains a large amount of information. In this embodiment, this conventional initial access signal is referred to as the first initial access signal. Specifically, the first initial access signal is a signal (synchronization signal and / or broadcast information) for informing the terminal device of information regarding initial access to the cellular network, and is a signal used in conventional standards. For example, the first initial access signal may be an initial access signal having a signal configuration defined in the 5G (NR) communication standard (e.g., SSB and / or SIB1), or it may be an initial access signal having a signal configuration defined in the communication standard of a generation prior to 5G (e.g., 4G (LTE)) (e.g., PSS / SSS and / or SIB1).

[0025] To solve the above problems, the communication point of this embodiment can transmit a lightweight initial access signal (i.e., an initial access signal that reduces the amount of information transmitted and the resources required for transmission compared to the conventional initial access signal (first initial access signal)) to a terminal device. In this embodiment, this lightweight initial access signal is called the second initial access signal. The second initial access signal, like the first initial access signal, is a signal (synchronization signal and / or broadcast information) for informing the terminal device of information regarding initial access to the wireless network. To achieve high power efficiency, the second initial access signal is configured to require less resources to transmit the information constituting the initial access signal than the first initial access signal. For example, the second initial access signal does not include at least one piece of information constituting the first initial access signal, and requires less resources to transmit than the first initial access signal. Here, the information included in the second initial access signal may be limited to the minimum information necessary for the terminal device to initially access the communication point.

[0026] The terminal device receives a second initial access signal from the communication point. The terminal device then performs initial access to the communication point based on the second initial access signal.

[0027] This eliminates the need to transmit excessive information unnecessarily to achieve low latency, resulting in high power efficiency even in environments with a small number of connected devices (or in environments with infrequent connections).

[0028] The wireless network equipped with the communication points in this embodiment is not limited to a cellular network, but may also be a cell-free network as described later. In a cell-free network, many communication points are deployed, so there is a great demand for power saving. By configuring the communication points to be able to transmit a second initial access signal, a cell-free network with high power efficiency can be realized.

[0029] Furthermore, the communication point may be capable of transmitting multiple initial access signal patterns. These multiple initial access signal patterns may include not only a second initial access signal but also a first initial access signal. The communication point may also switch the initial access signal it transmits according to predetermined conditions. For example, the communication point may switch the initial access signal it transmits from the first initial access signal to the second initial access signal, or from the second initial access signal to the first initial access signal. This allows the communication point to transmit the optimal initial access signal according to the situation. As a result, wireless communication with high communication performance is realized.

[0030] If multiple initial access signal patterns can be transmitted, the communication point may notify the terminal device which of the multiple initial access signal patterns it is transmitting. This prevents the terminal device from wasting resources trying to determine which initial access signal pattern is being transmitted. As a result, high-performance wireless communication is achieved.

[0031] Having outlined the basics of this embodiment, the communication system 1 of this embodiment will now be described in detail.

[0032] <<2. Configuration of the Communication System>> First, we will explain the configuration of communication system 1.

[0033] Figure 2 shows an example configuration of the communication system 1 according to this embodiment. The communication system 1 comprises a management device 10, a base station 20, a relay station 30, and a terminal device 40. The communication system 1 provides a wireless network (mobile network) that enables mobile communication to users through the coordinated operation of each wireless communication device that constitutes the communication system 1.

[0034] The wireless network (mobile network) in this embodiment may be, for example, a cellular network / cell-free network composed of a wireless access network (RAN) and a core network (CN). A cell-free network is a wireless network that eliminates cell boundaries in a conventional cell configuration (cellular network) centered on a base station. The wireless network (mobile network) may also include terminal devices 40. In this embodiment, a wireless communication device is a device that has wireless communication functionality, and in the example in Figure 2, this corresponds to a base station 20, a relay station 30, and a terminal device 40.

[0035] The communication system 1 may include multiple management devices 10, base stations 20, relay stations 30, and terminal devices 40. In the example in Figure 2, the communication system 1 includes multiple management devices 10 １ and 10 ２ It is equipped with, and as base station 20, １ , 20 ２ , and 20 ３ It is equipped with a relay station 30. １ and 30 ２ It is equipped with terminal device 40 as terminal device 40 １ , 40 ２ , and 40 ３ It is equipped with.

[0036] The terminal device 40 may be configured to connect to the network using radio access technologies (RATs) such as LTE (Long Term Evolution), NR (New Radio), B5G (Beyond 5G), 6G, Wi-Fi®, and Bluetooth®. In this case, the terminal device 40 may be configured to use different radio access technologies (wireless communication methods). For example, the terminal device 40 may be configured to use NR and Wi-Fi. Also, the terminal device 40 may be configured to use different cellular communication technologies / cell-free communication technologies (e.g., LTE, NR, B5G, or 6G). In the following description, the terminal device 40 may be referred to as UE (User Equipment) 40.

[0037] LTE and NR are types of cellular communication technologies that enable mobile communication for terminal devices by arranging multiple cell-like areas covered by devices with electromagnetic wave transmission and reception capabilities (e.g., base stations or TRPs (Transmission and Reception Points)). B5G and 6G are types of cellular / cell-free communication technologies that have the potential to enable mobile communication for terminal devices. Cell-free communication technology is a technology that eliminates cell boundaries in conventional cellular networks. Cell-free communication technology may also be considered a type of cellular communication technology. In this case, it is possible to appropriately replace "cellular" with "cell-free" or vice versa in the following explanation.

[0038] In the following explanation, "LTE" includes LTE-A (LTE-Advanced), LTE-A Pro (LTE-Advanced Pro), and EUTRA (Evolved Universal Terrestrial Radio Access). Furthermore, "NR" includes NRAT (New Radio Access Technology) and FEUTRA (Further EUTRA). A single base station or single TRP may manage one or more cells. In the following explanation, a cell corresponding to LTE will be referred to as an LTE cell, and a cell corresponding to NR will be referred to as an NR cell.

[0039] NR (Radio Wave) is the fifth-generation wireless access technology following LTE (fourth-generation communication including LTE-Advanced and LTE-Advanced Pro). NR is a wireless access technology that can support various use cases, including eMBB (Enhanced Mobile Broadband), mMTC (Massive Machine Type Communications), and URLLC (Ultra-Reliable and Low Latency Communications). NR was standardized in 3GPP (3rd Generation Partnership Project) Rel-15 and later as a technical framework to address the usage scenarios, requirements, and deployment scenarios in these use cases. Furthermore, 3GPP is considering next-generation technologies, including enhancements to the NR standard. For example, in Rel-19, standardization activities are underway for the next-generation communication standard, 6G (B5G (Beyond 5G)).

[0040] 6G is the next generation of cellular / cell-free communication technology following NR (Non-Reactive Network) and 5GS (5G system), which are fifth-generation mobile communication technologies. 6G requires the simultaneous realization of multiple axes: high speed, large capacity, low latency, high reliability, and massive simultaneous connections. 6G includes wireless access technology and network technologies between base stations, core networks, and data networks. Furthermore, 6G includes technologies for the extreme connectivity of eMBB, mMTC, and URLLLC, which were key use cases or requirements in NR. 6G also includes new technologies in new areas. For example, 6G may include technologies related to AI (Cognitive Network, AI Native Air Interface), sensing (Radar / RF sensing, including network as a sensor), and terahertz communication.

[0041] The wireless network described above or below may support at least one of the following radio access technologies (RATs): LTE, NR, B5G, 6G, etc. LTE, NR, B5G, and 6G are types of cellular / cell-free communication technologies. The wireless access method used by communication system 1 is not limited to LTE, NR, B5G, or 6G, but may also be other wireless access methods such as W-CDMA (Wideband Code Division Multiple Access) or cdma2000 (Code Division Multiple Access 2000).

[0042] Furthermore, the base station 20 and the relay station 30 may be ground stations or non-ground stations. Non-ground stations may be satellite stations or aircraft stations. If a non-ground station is a satellite station, the wireless network may be a bent-pipe (transparent) type mobile satellite communication system.

[0043] In this embodiment, "ground station" and "ground base station" refer to base stations and relay stations installed on the ground. Here, "ground" is a broad term that includes not only land but also underground, on water, and underwater. In the following description, "ground station" may be replaced with "gateway."

[0044] Furthermore, LTE base stations are sometimes referred to as eNodeB (Evolved Node B) or eNB. Similarly, NR base stations are sometimes referred to as gNodeB or gNB. 6G base stations are sometimes referred to as 6G NodeB (6GNB). In addition, for LTE, NR, and 6G, terminal equipment (also called mobile stations or terminals) is sometimes referred to as UE (User Equipment). Terminal equipment is a type of communication device and is also called a mobile station or terminal.

[0045] Furthermore, the terminal device 40 may be able to connect to the network using wireless access technologies (wireless communication methods) other than LTE, NR, B5G, 6G, Wi-Fi, and Bluetooth. For example, the terminal device 40 may be able to connect to the network using LPWA (Low Power Wide Area) communication. Also, the terminal device 40 may be able to connect to the network using a proprietary wireless communication standard.

[0046] Here, LPWA communication refers to wireless communication that enables low-power, wide-area communication. For example, LPWA communication refers to IoT (Internet of Things) wireless communication using specified low-power radio (e.g., the 920 MHz band) or the ISM (Industry-Science-Medical) band. LPWA communication may also include LTE-M and / or C-IoT (Cellular IoT), represented by NB-IoT, which operate in the cellular frequency band. The LPWA communication used by the terminal device 40 may conform to the LPWA standard. The LPWA standard may be at least one of, for example, ELTRES, ZETA, SIGFOX, LoRaWAN, LTE-M, and NB-IoT. Of course, the LPWA standard is not limited to these, and other LPWA standards may also be used.

[0047] Each wireless communication device shown in Figure 2 can be considered a device in a logical sense. That is, a part of each wireless communication device may be implemented using a virtual machine (VM), a container such as Docker, etc., and these may be implemented on the same physical hardware.

[0048] In this embodiment, the concept of a wireless communication device includes not only portable mobile devices (terminal devices) such as mobile terminals, but also devices installed on structures or mobile objects. The structure or mobile object itself may be considered a wireless communication device. Furthermore, the concept of a wireless communication device includes not only the terminal device 40, but also the base station 20 and the relay station 30. A wireless communication device is a type of processing device or information processing device. A wireless communication device can also be described as a transmitting device or a receiving device.

[0049] The configurations of each wireless communication device constituting communication system 1 are described below in detail. Note that the configurations of each wireless communication device shown below are merely examples. The configurations of each wireless communication device may differ from those shown below.

[0050] <2-1. Example of Management Device Configuration> Next, an example of the configuration of the management device 10 will be explained.

[0051] The management device 10 is an information processing device (computer) that manages the wireless network. For example, the management device 10 is an information processing device that manages the communications of the base station 20.

[0052] The management device 10 may be a device that constitutes the core network CN. For example, the management device 10 may be a device that functions as an MME (Mobility Management Entity). Alternatively, the management device 10 may be a device that functions as an AMF (Access and Mobility Management Function) and / or an SMF (Session Management Function). The MME, AMF, and SMF are Control Plane Network Function nodes in the core network CN. The management device 10 may also be a device that functions as a Control Plane Network Function (6G CPNF) in 6G. The 6G CPNF may consist of one or more logical nodes.

[0053] Of course, the functions of the management device 10 are not limited to MME, AMF, SMF, and 6G CPNF. The management device 10 may also be a device that has the functions of NSSF (Network Slice Selection Function), AUSF (Authentication Server Function), PCF (Policy Control Function), and UDM (Unified Data Management). Furthermore, the management device 10 may also be a device that has the function of HSS (Home Subscriber Server).

[0054] Furthermore, the management device 10 may also have gateway functionality. For example, the management device 10 may function as an S-GW (Serving Gateway) or a P-GW (Packet Data Network Gateway). The management device 10 may also function as a UPF (User Plane Function). In this case, the management device 10 may have multiple UPFs. The management device 10 may also be a device that functions as a User Plane Network Function (6G UPNF) in 6G.

[0055] The core network (CN) consists of multiple network functions, each of which may be aggregated in a single physical device or distributed across multiple physical devices. In other words, the management device 10 can be distributed across multiple devices. Furthermore, this distributed arrangement may be controlled to be performed dynamically. The base station 20, the relay station 30, and the management device 10 constitute a single network and provide wireless communication services to the terminal device 40. The management device 10 is connected to the internet, and the terminal device 40 can use various services provided via the internet through the base station 20 and / or the relay station 30.

[0056] Note that the management device 10 does not necessarily have to be a device that constitutes the core network CN. For example, suppose the core network CN is the core network of W-CDMA (Wideband Code Division Multiple Access) or cdma2000 (Code Division Multiple Access 2000). In this case, the management device 10 may be a device that functions as an RNC (Radio Network Controller).

[0057] Figure 3 shows the configuration of the management device 10 according to this embodiment. The management device 10 comprises a communication unit 11, a storage unit 12, and a control unit 13. The configuration shown in Figure 3 is a functional configuration, and the hardware configuration may differ. Furthermore, the functions of the management device 10 may be implemented by statically or dynamically distributing them across multiple physically separated configurations. The management device 10 may be composed of multiple server devices.

[0058] The communication unit 11 is a communication interface for communicating with a wireless communication device (for example, a base station 20). The communication unit 11 may be a network interface or an equipment connection interface. The communication unit 11 may be a LAN (Local Area Network) interface such as a NIC (Network Interface Card), or a USB interface configured by a USB (Universal Serial Bus) host controller or a USB port. The communication unit 11 may be a wired interface or a wireless interface. The communication unit 11 is controlled by the control unit 13.

[0059] The memory unit 12 is a read / write storage device such as DRAM (Dynamic Random Access Memory), SRAM (Static Random Access Memory), flash memory, or a hard disk. The memory unit 12 stores, for example, the connection status of the terminal device 40. The memory unit 12 stores the RRC (Radio Resource Control) status and ECM (EPS Connection Management) or 5G System CM (Connection Management) status of the terminal device 40. The memory unit 12 may also function as a home memory that stores the location information of the terminal device 40.

[0060] The control unit 13 is a controller that controls each part of the management device 10. The control unit 13 may be implemented by a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). More specifically, the control unit 13 may be implemented by the processor executing various programs stored in the internal storage device of the management device 10 using RAM (Random Access Memory) or the like as a working area. The control unit 13 may be implemented by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). Alternatively, the control unit 13 may be implemented by a GPU (Graphics Processing Unit). A CPU, MPU, ASIC, FPGA, and GPU can all be considered as controllers. The control unit 13 may be composed of multiple physically separated objects. For example, the control unit 13 may be composed of multiple semiconductor chips.

[0061] The operation of the control unit 13 may be the same as the operation of the control unit (control unit 23, control unit 33, or control unit 43) of the base station 20, relay station 30, or terminal device 40.

[0062] <2-2. Example of Base Station Configuration> Next, an example of the configuration of base station 20 will be explained.

[0063] Base station 20 is a wireless communication device that communicates wirelessly with other wireless communication devices (for example, a relay station 30, a terminal device 40, or another base station 20). Base station 20 may communicate wirelessly with terminal device 40 via relay station 30, or it may communicate wirelessly with terminal device 40 directly.

[0064] Base station 20 is a device equivalent to a wireless base station (for example, BS (Base Station), Node B, eNB, gNB, or 6GNB) or a wireless access point (Access Point). In the following description, base station 20 may be referred to as BS (Base Station), Node B, eNB, gNB, 6GNB, or BS20.

[0065] Base station 20 may be a radio relay station (for example, a relay station 30 described later). Base station 20 may be an optical extension device called an RRH (Remote Radio Head). Base station 20 may be a receiving station such as an FPU (Field Pickup Unit). Base station 20 may be an IAB (Integrated Access and Backhaul) donor node or IAB relay node that provides radio access lines and radio backhaul lines by time division multiplexing, frequency division multiplexing, or spatial division multiplexing.

[0066] The wireless access technology used by base station 20 may be cellular communication technology / cell-free communication technology. The wireless access technology used by base station 20 may be wireless LAN technology. The wireless access technology used by base station 20 may be LPWA (Low Power Wide Area) communication technology. However, the wireless access technology used by base station 20 is not limited to these, and other wireless access technologies may be used. The wireless communication used by base station 20 may be wireless communication using millimeter waves or wireless communication using terahertz waves. The wireless communication used by base station 20 may be wireless communication using radio waves or wireless communication using infrared or visible light (optical wireless). In addition, base station 20 may be capable of NOMA (Non-Orthogonal Multiple Access) communication with terminal device 40. Here, NOMA communication refers to communication using non-orthogonal resources (transmission, reception, or both). Base station 20 may also be capable of NOMA communication with other base stations 20.

[0067] Furthermore, base station 20 may be able to communicate with the core network via a base station-core network interface (e.g., NG Interface, S1 Interface, etc.). This interface may be either wired or wireless. Also, base stations may be able to communicate with other base stations via an inter-base station interface (e.g., Xn Interface, X2 Interface, F1 Interface, etc.). This interface may be either wired or wireless.

[0068] The concept of a base station (also called "base station equipment") includes not only donor base stations but also relay base stations (also called "relay stations"). A relay base station may be any one of the following: an RF Repeater, a Smart Repeater, or an Intelligent Surface. Furthermore, the concept of a base station may also include roadside units (RSUs). In addition, the concept of a base station may include not only structures equipped with base station functions but also equipment installed on those structures.

[0069] Structures include buildings such as skyscrapers, houses, transmission towers, train stations, airports, ports, office buildings, school buildings, hospitals, factories, commercial facilities, and stadiums. The concept of structures also includes not only buildings but also non-building structures such as tunnels, bridges, dams, walls, and steel columns, as well as equipment such as cranes, gates, and wind turbines. The concept of structures also includes not only structures on land (on the surface in the narrow sense) or underground, but also structures on water such as piers or megafloats, and underwater structures such as oceanographic observation equipment. A base station can also be described as an information processing device.

[0070] Base station 20 may be a donor station or a relay station. Furthermore, base station 20 may be a fixed station or a mobile station. A mobile station is a wireless communication device (e.g., a base station) configured to be mobile. In this case, base station 20 may be a device installed on a mobile device or the mobile device itself. For example, a relay station with mobility can be considered a base station 20 as a mobile station. Additionally, devices that are inherently mobile and equipped with base station functions (or at least some of the functions of a base station), such as vehicles, UAVs (Unmanned Aerial Vehicles) represented by drones, and smartphones, also qualify as base station 20 as a mobile station.

[0071] Here, the moving object may be a mobile device such as a smartphone or mobile phone. The moving object may also be a moving object that moves on land (ground in the narrow sense) (for example, a car, bicycle, bus, truck, motorcycle, train, or linear motor car), or a moving object that moves underground (for example, inside a tunnel) (for example, a subway). The moving object may also be a moving object that moves on water (for example, a passenger ship, cargo ship, or hovercraft), or a moving object that moves underwater (for example, a submersible boat, submarine, or unmanned submersible). The moving object may also be a moving object that moves within the atmosphere (for example, an airplane, airship, or drone).

[0072] Base station 20 may be a ground base station (ground station) installed on the ground. Base station 20 may be a base station located on a structure on the ground, or a base station installed on a mobile body moving on the ground. Base station 20 may be an antenna installed on a structure such as a building and a signal processing device connected to that antenna. Base station 20 may be the structure or the mobile body itself. "Ground" refers to ground in a broad sense, including not only land (ground in the narrow sense) but also underground, on water, and underwater. Base station 20 is not limited to a ground base station. If communication system 1 is a satellite communication system, base station 20 may be an aircraft station. From the perspective of a satellite station, an aircraft station located on Earth is a ground station.

[0073] The base station 20 is not limited to a ground station. The base station 20 may be a non-ground base station (non-ground station) capable of floating in the air or space. The base station 20 may be an aircraft station or a satellite station.

[0074] A satellite station is a radio communication device capable of floating outside the atmosphere. A satellite station may be a device mounted on a spacecraft such as an artificial satellite, or it may be the spacecraft itself. A spacecraft is a mobile object that moves outside the atmosphere. A spacecraft may be at least one of the following: an artificial satellite, a spacecraft, a space station, and a probe. Of course, a spacecraft may also be an artificial celestial body other than these. The satellite that becomes a satellite station may be a low Earth orbit (LEO) satellite, a medium Earth orbit (MEO) satellite, a geostationary Earth orbit (GEO) satellite, or a highly elliptical orbit (HEO) satellite. A satellite station may be a device mounted on a low Earth orbit satellite, a medium Earth orbit satellite, a geostationary satellite, or a highly elliptical orbit satellite.

[0075] An aircraft station is a radio communication device capable of floating within the atmosphere of an aircraft or similar vessel. An aircraft station may be a device mounted on an aircraft or similar vessel, or it may be the aircraft itself. The concept of an aircraft includes not only heavy aircraft such as airplanes or gliders, but also light aircraft such as balloons or airships. The concept of an aircraft also includes not only heavy or light aircraft, but also rotary-wing aircraft such as helicopters or autogyros. An aircraft station, or an aircraft on which an aircraft station is mounted, may be an unmanned aerial vehicle such as a drone.

[0076] The concept of unmanned aerial vehicles includes unmanned aircraft systems (UAS) and tethered UAS. It also includes lighter than air UAS (LTA) and heavier than air UAS (HTA). Furthermore, it includes high-altitude UAS platforms (HAPs).

[0077] The coverage size of the base station 20 may be relatively large, such as a macrocell, or relatively small, such as a picocell. The coverage size of the base station 20 may also be extremely small, such as a femtocell. The base station 20 may have a beamforming function. The base station 20 may form cells or service areas for each beam. Furthermore, or alternatively, in addition to beamforming which gives directionality to the beam, the base station 20 may have a function that delivers the desired wave precisely to a predetermined point by further considering distance information from the base station 20's antenna. This function may be called beam focusing or point forming. The base station 20 may also be configured to acquire sensing data by performing sensing using the beam.

[0078] Figure 4 shows the configuration of a base station 20 according to this embodiment. The base station 20 comprises a wireless communication unit 21, a storage unit 22, and a control unit 23. However, the configuration shown in Figure 4 is a functional configuration, and the hardware configuration may differ. Furthermore, the functions of the base station 20 may be distributed and implemented across multiple physically separated configurations.

[0079] Note that the base station 20 does not necessarily have to have all of the above-mentioned or later-described configurations. Also, the base station 20 may have configurations other than those described above or later.

[0080] The wireless communication unit 21 is a signal processing unit for wireless communication with other wireless communication devices (for example, at least one of terminal devices 40 and other base stations 20). The wireless communication unit 21 may be called a wireless transceiver or simply a transceiver. In this case, the wireless communication unit 21 may be a transceiver conforming to the specifications defined in the 3GPP Technical Specification (TS) (hereinafter referred to as a 3GPP transceiver). The 3GPP transceiver may be a 3G transceiver, a 4G (LTE) transceiver, a 5G (NR) transceiver, or a 5G or later generation transceiver (for example, 6G). The wireless communication unit 21 is controlled by the control unit 23. The wireless communication unit 21 supports one or more wireless access schemes. The wireless communication unit 21 may support at least one of 4G (LTE), 5G (NR), B5G (Beyond 5G), and 6G. The wireless communication unit 21 may support 4G (LTE), 5G (NR), B5G, and 6G, as well as W-CDMA and cdma2000, etc. The wireless communication unit 21 may also support automatic retransmission technologies such as HARQ (Hybrid Automatic Repeat reQuest). Some or all of the processing performed by the wireless communication unit 21 may be performed by the control unit 23.

[0081] The wireless communication unit 21 comprises a transmission processing unit 211, a reception processing unit 212, and an antenna 213. Alternatively, the wireless communication unit 21 may be considered as at least one of the transmission processing unit 211, the reception processing unit 212, and the antenna 213. The wireless communication unit 21 may include multiple transmission processing units 211, reception processing units 212, and antennas 213. If the wireless communication unit 21 supports multiple wireless access methods, each part of the wireless communication unit 21 may be configured separately for each wireless access method. The transmission processing unit 211 and the reception processing unit 212 may be configured separately for 4G (LTE), 5G (NR), B5G, and 6G. The antenna 213 may be composed of multiple antenna elements, for example, multiple patch antennas. The wireless communication unit 21 may have a beamforming function. For example, the wireless communication unit 21 may have a polarization beamforming function that uses vertical polarization (V polarization) and horizontal polarization (H polarization) (or a polarization beamforming function that uses dual polarization in polarization directions of 45 degrees and -45 degrees from the vertical). The wireless communication unit 21 may also transmit the sensing signals described above or below.

[0082] The transmission processing unit 211 performs the transmission processing of downlink control information and downlink data. For example, the transmission processing unit 211 encodes the downlink control information and downlink data input from the control unit 23 using encoding methods such as block encoding, convolutional encoding, or turbo encoding. Here, encoding may be performed using polar code or LDPC code (Low Density Parity Check Code). The transmission processing unit 211 then modulates the encoded bits using a predetermined modulation method (for example, BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), 16QAM (16 Quadrature Amplitude Modulation), 64QAM (64 Quadrature Amplitude Modulation), 256QAM (256 Quadrature Amplitude Modulation), or a higher-order multi-level modulation method). In this case, the signal points on the constellation do not necessarily need to be equidistant. Furthermore, the constellation may be a non-uniform constellation (NUC). The transmission processing unit 211 then multiplexes the modulation symbols and downlink reference signals for each channel and places them on predetermined resource elements. The transmission processing unit 211 then performs various signal processing on the multiplexed signals. For example, the transmission processing unit 211 performs processing such as conversion to the frequency domain using the Fast Fourier Transform, addition of guard intervals (cyclic prefixes), generation of baseband digital signals, conversion to analog signals, quadrature modulation, upconversion, removal of extraneous frequency components, and power amplification. The signals generated by the transmission processing unit 211 are transmitted from the antenna 213.

[0083] The receiving processing unit 212 processes the uplink signal received via the antenna 213. For example, the receiving processing unit 212 performs down-conversion, removal of unwanted frequency components, amplification level control, quadrature demodulation, conversion to a digital signal, removal of guard intervals (cyclic prefixes), and extraction of frequency domain signals using Fast Fourier Transform on the uplink signal. Then, the receiving processing unit 212 separates the uplink channels and uplink reference signals, such as PUSCH (Physical Uplink Shared Channel) and PUCCH (Physical Uplink Control Channel), from the processed signal. The receiving processing unit 212 also demodulates the received signal using a modulation scheme such as BPSK or QPSK for the modulation symbols of the uplink channels. The modulation scheme used for demodulation may be 16QAM, 64QAM, or 256QAM. In this case, the signal points on the constellation do not necessarily need to be equidistant. The constellation may be a non-uniform constellation (NUC). The receiving processing unit 212 then performs decoding on the encoded bits of the demodulated uplink channel. The decoded uplink data and uplink control information are output to the control unit 23.

[0084] Antenna 213 is an antenna device that converts electric current and radio waves to each other. Antenna 213 may consist of one antenna element, for example, one patch antenna. Antenna 213 may consist of multiple antenna elements, for example, multiple patch antennas. If antenna 213 consists of multiple antenna elements, the wireless communication unit 21 may have a beamforming function. The wireless communication unit 21 may be configured to generate a directional beam by controlling the directivity of the radio signal using multiple antenna elements. Antenna 213 may be a dual-polarization antenna. If antenna 213 is a dual-polarization antenna, the wireless communication unit 21 may use vertical polarization (V polarization) and horizontal polarization (H polarization) (or dual polarization in polarization directions of 45 degrees and -45 degrees from the vertical) when transmitting a radio signal. The wireless communication unit 21 may control the directivity of the transmitted radio signal using vertical polarization and horizontal polarization (or dual polarization in polarization directions of 45 degrees and -45 degrees from the vertical). Furthermore, the wireless communication unit 21 may transmit and receive signals spatially multiplexed through multiple layers composed of multiple antenna elements.

[0085] The memory unit 22 is a read / write storage device such as DRAM, SRAM, flash memory, or a hard disk.

[0086] The control unit 23 is a controller that controls various parts of the base station 20. The control unit 23 controls the wireless communication unit 21 to perform wireless communication with other wireless communication devices (for example, a relay station 30, a terminal device 40, or another base station 20). The control unit 23 may be implemented by a processor such as a CPU or MPU. Specifically, the control unit 23 may be implemented by the processor executing various programs stored in the internal memory of the base station 20 using RAM or the like as a working area. The control unit 23 may be implemented by an integrated circuit such as an ASIC or FPGA. Furthermore, the control unit 23 may be implemented by a GPU. CPU, MPU, ASIC, FPGA, and GPU can all be considered as controllers. The control unit 23 may be composed of multiple physically separated objects. For example, the control unit 23 may be composed of multiple semiconductor chips.

[0087] The control unit 23 comprises at least one block consisting of a transmission control unit 231, a reception control unit 232, and an allocation unit 233. The control unit 23 may comprise multiple of these blocks, or it may comprise only one of each.

[0088] Each block constituting the control unit 23 (transmission control unit 231 to allocation unit 233) is a functional block that represents the function of the control unit 23. These functional blocks may be software blocks or hardware blocks. For example, each of the above-mentioned functional blocks may be a single software module implemented in software (including microprograms), or a single circuit block on a semiconductor chip (die). Of course, each functional block may also be a single processor or a single integrated circuit. The control unit 23 may be composed of functional units different from the above-mentioned functional blocks. The configuration method of the functional blocks is arbitrary. The operation of the control unit 23 may be the same as the operation of the control units (control unit 13, control unit 33, or control unit 43) of the management device 10, relay station 30, or terminal device 40.

[0089] In some embodiments, the base station 20 may be composed of a collection of multiple physical or logical devices. For example, the base station 20 in this embodiment may be distinguished into multiple devices such as a BBU (Baseband Unit) and an RU (Radio Unit). The base station 20 may be interpreted as a collection of these multiple devices. Furthermore, the base station may consist of either a BBU or an RU, or both. The BBU and RU may be connected by a predetermined interface, such as an eCPRI (enhanced Common Public Radio Interface).

[0090] RU may be rephrased as RRU (Remote Radio Unit) or RD (Radio DoT). RU may correspond to gNB-DU (gNB Distributed Unit), which will be described later. BBU may correspond to gNB-CU (gNB Central Unit), which will be described later. RU may be a device integrally formed with the antenna. The antenna of the base station 20, for example, an antenna integrally formed with the RU, may employ an Advanced Antenna System and support MIMO (Multiple-Input Multiple-Output) or beamforming, such as FD-MIMO. The antenna of the base station 20 may have, for example, 64 transmitting antenna ports and 64 receiving antenna ports.

[0091] The antenna mounted on the RU may be an antenna panel composed of one or more antenna elements, and the RU may be equipped with one or more antenna panels. The RU may be equipped with two types of antenna panels: a horizontally polarized antenna panel and a vertically polarized antenna panel. The RU may be equipped with two types of antenna panels: a right-hand circularly polarized antenna panel and a left-hand circularly polarized antenna panel, or an antenna panel with a polarization direction of 45 degrees from the vertical and an antenna panel with a polarization direction of -45 degrees. Multiple antennas with these multiple polarization directions may be mounted on a single antenna panel. The RU may form and control independent beams for each antenna panel.

[0092] Multiple base stations 20 may be connected to each other. One or more base stations 20 may be included in a radio access network (RAN). In this case, the base stations 20 may simply be referred to as RAN, RAN node, AN (Access Network), or AN node, etc. In LTE, RAN may be called EUTRAN (Enhanced Universal Terrestrial RAN). In NR, RAN may be called NGRAN. Also, in 6G, RAN may be called 6GRAN. In W-CDMA (UMTS), RAN may be called UTRAN.

[0093] An LTE base station 20 may be referred to as eNodeB (Evolved Node B) or eNB. In this case, EUTRAN includes one or more eNodeBs (eNBs). An NR base station 20 may be referred to as gNodeB or gNB. In this case, NGRAN includes one or more gNBs. A 6G base station may be referred to as 6GNodeB, 6gNodeB, 6GNB, or 6gNB. In this case, 6GRAN includes one or more 6GNBs. EUTRAN may also include gNBs (en-gNBs) connected to the core network (EPC) in an LTE communication system (EPS). NGRAN may also include ng-eNBs connected to the core network 5GC in a 5G communication system (5GS).

[0094] If base station 20 is an eNB, gNB, 6GNB, etc., base station 20 may be referred to as 3GPP Access. If base station 20 is an Access Point, base station 20 may be referred to as Non-3GPP Access. Base station 20 may also be an optical extension device called an RRH (Remote Radio Head). If base station 20 is a gNB, base station 20 may be a combination of the gNB-CU and gNB-DU described above, or it may be either a gNB-CU or a gNB-DU.

[0095] Here, the gNB-CU hosts multiple upper layers of the Access Stratum (e.g., RRC (Radio Resource Control), SDAP (Service Data Adaptation Protocol), PDCP (Packet Data Convergence Protocol)) for communication with the UE. On the other hand, the gNB-DU hosts multiple lower layers of the Access Stratum (e.g., RLC (Radio Link Control), MAC (Medium Access Control), PHY (Physical layer)). That is, among the messages / information described later, RRC signaling (quasi-static notifications) may be generated by the gNB-CU, while MAC CE and DCI (dynamic notifications) may be generated by the gNB-DU. Alternatively, among the RRC configuration (quasi-static notifications), some configurations, such as IE:cellGroupConfig, may be generated by the gNB-DU, and the remaining configurations may be generated by the gNB-CU. These configurations may be transmitted or received via the F1 interface.

[0096] Base station 20 may be configured to communicate with other base stations. If multiple base stations 20 are eNBs or a combination of eNB and en-gNB, these base stations 20 may be connected by an X2 interface. If multiple base stations 20 are gNBs or a combination of gn-eNB and gNB, these base stations 20 may be connected by an Xn interface. If multiple base stations 20 are a combination of gNB-CU and gNB-DU, these base stations 20 may be connected by the F1 interface described above. Messages / information described later (e.g., RRC signaling, MAC CE (MAC Control Element), or DCI (Downlink Control Information), etc.) may be transmitted between multiple base stations 20 via these inter-base station interfaces (e.g., X2 interface, Xn interface, or F1 interface, etc.).

[0097] The cells provided by the base station 20 are sometimes called Serving Cells. The concept of a Serving Cell includes PCell (Primary Cell) and SCell (Secondary Cell). When dual connectivity is provided to the terminal device 40, the PCell provided by the Master Node (MN) and zero or one or more SCells are sometimes called a Master Cell Group. Dual connectivity may be at least one of EUTRA-EUTRA Dual Connectivity, EUTRA-NR Dual Connectivity (ENDC), EUTRA-NR Dual Connectivity with 5GC, NR-EUTRA Dual Connectivity (NEDC), NR-NR Dual Connectivity, NR-6G Dual Connectivity, and 6G-NR Dual Connectivity. Of course, dual connectivity is not limited to these.

[0098] A serving cell may include a PSCell (Primary Secondary Cell, or Primary SCG Cell). When dual connectivity is provided to the terminal device 40, the PSCell provided by the SN (Secondary Node) and zero or one or more SCells may be called an SCG (Secondary Cell Group). Unless special settings are made (e.g., PUCCH on SCell), the physical uplink control channel (PUCCH) is transmitted by PCell and PSCell, but not by SCell. Radio link failure is detected by PCell and PSCell, but not by SCell (and does not need to be detected). Because PCell and PSCell play special roles within the serving cell, they are also called SpCell (Special Cell).

[0099] A single cell may be associated with one downlink component carrier and one uplink component carrier. The system bandwidth corresponding to a single cell may be divided into multiple Bandwidth Parts (BWPs). In this case, one or more BWPs may be configured in the terminal device 40, and one BWP may be used by the terminal device 40 as an active BWP. The radio resources available to the terminal device 40, such as frequency band, numerology (subcarrier spacing), or slot configuration, may differ for each cell, each component carrier, or each BWP.

[0100] <2-3. Example of Relay Station Configuration> Next, an example of the configuration of relay station 30 will be explained.

[0101] The relay station 30 is a wireless communication device that acts as a repeater for the base station 20. The relay station 30 is a type of base station (for example, the base station 20 described above). The relay station 30 is also a type of information processing device. The relay station 30 can also be called a relay base station. The relay station 30 may also be a device called a repeater (for example, an RF Repeater, Smart Repeater, or Intelligent Surface). The relay station 30 is a wireless communication device that communicates wirelessly with other wireless communication devices (for example, the base station 20, the terminal device 40, or other relay stations 30).

[0102] The relay station 30 may be capable of NOMA communication with the terminal device 40. The relay station 30 relays communication between the base station 20 and the terminal device 40. The relay station 30 may be capable of wireless communication with other relay stations 30 and base station 20. The relay station 30 may be a ground station or a non-ground station. The relay station 30, together with the base station 20, constitutes a wireless access network RAN.

[0103] The relay station 30 may be a fixed device, a movable device, or a floating device. The coverage size of the relay station 30 is not limited to a specific size. The cells covered by the relay station 30 may be macrocells or small cells.

[0104] The device on which the relay station 30 is installed is not limited to a specific device, as long as the relay function is fulfilled. The relay station 30 may be installed in terminal devices such as smartphones, in automobiles, trains, or rickshaws, in balloons, airplanes, or drones, or in home appliances such as televisions, game consoles, air conditioners, refrigerators, or lighting fixtures. Furthermore, any device with a relay function may be considered as the relay station 30 itself.

[0105] The configuration of the relay station 30 may be the same as that of the base station 20 described above. The relay station 30 may be a device installed on a mobile device, or it may be the mobile device itself, similar to the base station 20 described above. The mobile device may be a mobile terminal such as a smartphone or mobile phone, as described above. The mobile device may be a mobile device that moves on land (ground in the narrow sense), or a mobile device that moves underground. The mobile device may be a mobile device that moves on water, or a mobile device that moves underwater. The mobile device may be a mobile device that moves within the atmosphere, or a mobile device that moves outside the atmosphere. The relay station 30 may be a ground station device, or a non-ground station device. The relay station 30 may be an aircraft station, a satellite station, etc.

[0106] The coverage size of the relay station 30 may range from large, like a macrocell, to small, like a picocell, similar to the base station 20. The coverage size of the relay station 30 may also be extremely small, like a femtocell. The relay station 30 may have beamforming capabilities. In this case, the relay station 30 may form cells or service areas for each beam. The relay station 30 may also have point forming capabilities. In this case, the relay station 30 may form cells or service areas for each point.

[0107] Figure 5 shows the configuration of the relay station 30 according to this embodiment. The relay station 30 comprises a wireless communication unit 31, a storage unit 32, and a control unit 33. However, the configuration shown in Figure 5 is a functional configuration, and the hardware configuration may differ. Furthermore, the functions of the relay station 30 may be distributed and implemented across multiple physically separated configurations.

[0108] It should be noted that the relay station 30 does not necessarily have all of the above-mentioned or later-described configurations. Furthermore, the relay station 30 may have configurations other than those described above or later.

[0109] The wireless communication unit 31 is a signal processing unit for wireless communication with other wireless communication devices (for example, at least one of terminal devices 40 and other relay stations 30). The wireless communication unit 31 may be called a wireless transceiver or simply a transceiver. In this case, the wireless communication unit 31 may be a transceiver conforming to the specifications defined in the 3GPP technical specifications (hereinafter referred to as a 3GPP transceiver). The 3GPP transceiver may be a 3G transceiver, a 4G (LTE) transceiver, a 5G (NR) transceiver, or a 5G or later generation transceiver (for example, 6G). The wireless communication unit 31 is controlled by the control unit 33. The wireless communication unit 31 supports one or more wireless access schemes. The wireless communication unit 31 may support at least one of 4G (LTE), 5G (NR), B5G, and 6G. The wireless communication unit 31 may support 4G (LTE), 5G (NR), B5G, and 6G, as well as W-CDMA and cdma2000, etc. The wireless communication unit 31 may also support automatic retransmission technologies such as HARQ. Some or all of the processing performed by the wireless communication unit 31 may be performed by the control unit 33.

[0110] The wireless communication unit 31 comprises a transmission processing unit 311, a reception processing unit 312, and an antenna 313. Alternatively, the wireless communication unit 31 may be considered as at least one of the transmission processing unit 311, the reception processing unit 312, and the antenna 313. The wireless communication unit 31 may include multiple transmission processing units 311, reception processing units 312, and antennas 313. If the wireless communication unit 31 supports multiple wireless access methods, each part of the wireless communication unit 31 may be configured separately for each wireless access method. The transmission processing unit 311 and the reception processing unit 312 may be configured separately for 4G (LTE), 5G (NR), B5G, and 6G. The antenna 313 may be composed of multiple antenna elements, for example, multiple patch antennas. The wireless communication unit 31 may have a beamforming function. For example, the wireless communication unit 31 may have a polarization beamforming function that uses vertical polarization (V polarization) and horizontal polarization (H polarization) (or a polarization beamforming function that uses dual polarization in polarization directions of 45 degrees and -45 degrees from the vertical). The wireless communication unit 31 may also transmit the sensing signals described above or below.

[0111] The transmission processing unit 311 performs the transmission processing of downlink control information and downlink data. For example, the transmission processing unit 311 encodes the downlink control information and downlink data input from the control unit 33 using an encoding method such as block coding, convolutional coding, or turbo coding. Here, the encoding may be done using polar coding or LDPC coding. The transmission processing unit 311 then modulates the encoded bits using a predetermined modulation method (for example, BPSK, QPSK, 16QAM, 64QAM, 256QAM, or a higher-order multi-level modulation method). In this case, the signal points on the constellation do not necessarily have to be equidistant. The constellation may also be a non-uniform constellation. The transmission processing unit 311 then multiplexes the modulation symbols and downlink reference signals for each channel and places them in predetermined resource elements. The transmission processing unit 311 then performs various signal processing on the multiplexed signals. For example, the transmission processing unit 311 performs processing such as conversion to the frequency domain using the Fast Fourier Transform, addition of a guard interval (cyclic prefix), generation of a baseband digital signal, conversion to an analog signal, quadrature modulation, upconversion, removal of extraneous frequency components, and power amplification. The signal generated by the transmission processing unit 311 is transmitted from the antenna 313.

[0112] The receiving processing unit 312 processes the uplink signal received via the antenna 313. For example, the receiving processing unit 312 performs down-conversion, removal of unwanted frequency components, control of amplification level, quadrature demodulation, conversion to a digital signal, removal of guard intervals (cyclic prefixes), and extraction of frequency domain signals using fast Fourier transform on the uplink signal. Then, the receiving processing unit 312 separates the uplink channel and uplink reference signals, such as PUSCH and PUCCH, from the processed signal. The receiving processing unit 312 also demodulates the received signal using a modulation scheme such as BPSK or QPSK for the modulation symbols of the uplink channel. The modulation scheme used for demodulation may be 16QAM, 64QAM, or 256QAM. In this case, the signal points on the constellation do not necessarily need to be equidistant. The constellation may be a non-uniform constellation (NUC). The receiving processing unit 312 then performs decoding on the encoded bits of the demodulated uplink channel. The decoded uplink data and uplink control information are output to the control unit 33.

[0113] Antenna 313 is an antenna device that converts electric current and radio waves to each other. Antenna 313 may consist of one antenna element, for example, one patch antenna. Antenna 313 may consist of multiple antenna elements, for example, multiple patch antennas. If antenna 313 consists of multiple antenna elements, the wireless communication unit 31 may have a beamforming function. The wireless communication unit 31 may be configured to generate a directional beam by controlling the directivity of the radio signal using multiple antenna elements. Antenna 313 may be a dual-polarization antenna. If antenna 313 is a dual-polarization antenna, the wireless communication unit 31 may use vertical polarization (V polarization) and horizontal polarization (H polarization) (or dual polarization in polarization directions of 45 degrees and -45 degrees from the vertical) when transmitting a radio signal. The wireless communication unit 31 may control the directivity of the transmitted radio signal using vertical polarization and horizontal polarization (or dual polarization in polarization directions of 45 degrees and -45 degrees from the vertical). Furthermore, the wireless communication unit 31 may transmit and receive signals spatially multiplexed through multiple layers composed of multiple antenna elements.

[0114] The memory unit 32 is a read / write storage device such as DRAM, SRAM, flash memory, or a hard disk.

[0115] The control unit 33 is a controller that controls various parts of the relay station 30. The control unit 33 controls the wireless communication unit 31 to perform wireless communication with other wireless communication devices (for example, a base station 20, a terminal device 40, or another relay station 30). The control unit 33 may be implemented by a processor such as a CPU or MPU. Specifically, the control unit 33 may be implemented by the processor executing various programs stored in the internal memory device of the relay station 30 using RAM or the like as a working area. The control unit 33 may be implemented by an integrated circuit such as an ASIC or FPGA. Furthermore, the control unit 33 may be implemented by a GPU. CPU, MPU, ASIC, FPGA, and GPU can all be considered as controllers. The control unit 33 may be composed of multiple physically separated objects. For example, the control unit 33 may be composed of multiple semiconductor chips.

[0116] The control unit 33 comprises at least one block consisting of a transmission control unit 331, a reception control unit 332, and an allocation unit 333. The control unit 33 may comprise multiple of these blocks, or it may comprise only one of each.

[0117] Each block constituting the control unit 33 (transmission control unit 331 to allocation unit 333) is a functional block that represents the function of the control unit 33. These functional blocks may be software blocks or hardware blocks. For example, each of the above-mentioned functional blocks may be a single software module implemented in software (including microprograms), or a single circuit block on a semiconductor chip (die). Of course, each functional block may also be a single processor or a single integrated circuit. The control unit 33 may be composed of functional units different from the above-mentioned functional blocks. The configuration method of the functional blocks is arbitrary. The operation of the control unit 33 may be the same as the operation of the control unit (control unit 13, control unit 23, or control unit 43) of the management device 10, base station 30, or terminal device 40.

[0118] The relay station 30 may also be an IAB relay node. The relay station 30 may operate as an IAB-MT (Mobile Termination) with respect to the IAB donor node that provides backhaul, and may operate as an IAB-DU (Distributed Unit) with respect to the terminal device 40 that provides access. The IAB donor node may be, for example, a base station 20. In this case, the IAB donor node may operate as an IAB-CU (Central Unit).

[0119] <2-4. Example of Terminal Device Configuration> Next, an example of the configuration of the terminal device 40 will be explained.

[0120] Terminal device 40 is a wireless communication device that performs wireless communication with other wireless communication devices (for example, base station 20, relay station 30, or other terminal device 40). In the following description, terminal device 40 may be referred to as UE (User Equipment) or UE40.

[0121] The terminal device 40 can be any form of information processing device (computer). For example, the terminal device 40 may be a mobile terminal such as a mobile phone, smart device (smartphone or tablet), PDA (Personal Digital Assistant), or notebook PC. Alternatively, the terminal device 40 may be a communication module connected to an information processing device (for example, an imaging device without wireless communication capabilities) and providing wireless communication capabilities to the information processing device. Alternatively, the terminal device 40 may be an imaging device equipped with wireless communication capabilities (for example, a camcorder).

[0122] Furthermore, the terminal device 40 may be a motorcycle or mobile relay vehicle equipped with communication equipment such as an FPU (Field Pickup Unit). The terminal device 40 may also be an M2M (Machine to Machine) device or an IoT (Internet of Things) device. Additionally, the terminal device 40 may be a wearable device such as a smartwatch.

[0123] Furthermore, the terminal device 40 may be an XR (Extended Reality) device such as an AR (Augmented Reality) device, a VR (Virtual Reality) device, or an MR (Mixed Reality) device. In this case, the XR device may be a glasses-type device such as AR glasses or MR glasses, or a head-mounted device such as a VR head-mounted display. When the terminal device 40 is an XR device, the terminal device 40 may be a standalone device consisting only of a user-worn portion (e.g., a glasses portion). Alternatively, the terminal device 40 may be a terminal-linked device consisting of a user-worn portion (e.g., a glasses portion) and a terminal portion (e.g., a smart device) that is linked to that portion.

[0124] Terminal device 40 may be capable of NOMA communication with other wireless communication devices (e.g., base station 20, relay station 30, or other terminal device 40). Terminal device 40 may use automatic retransmission technology such as HARQ when communicating with other wireless communication devices. Terminal device 40 may be capable of sidelink communication with other terminal devices 40. Terminal device 40 may use automatic retransmission technology such as HARQ when performing sidelink communication. Terminal device 40 may be capable of NOMA communication when performing sidelink communication with other terminal devices 40. Terminal device 40 may be capable of LPWA communication with other wireless communication devices. The wireless communication used by terminal device 40 may be wireless communication using millimeter waves. The wireless communication used by terminal device 40, including sidelink communication, may be wireless communication using radio waves, or wireless communication using infrared or visible light, i.e., optical wireless communication.

[0125] The terminal device 40 may be a mobile wireless communication device, i.e., a mobile device. The terminal device 40 may be a wireless communication device installed on a mobile device, or it may be the mobile device itself. The terminal device 40 may be a vehicle that moves on roads, such as an automobile, bus, truck, or motorcycle, or a train that runs on tracks, or it may be a wireless communication device mounted on such a vehicle. The mobile device may be a mobile terminal, or it may be a mobile device that moves on land (ground in the narrow sense), underground, on water, or underwater. Furthermore, the mobile device may be a mobile device that moves within the atmosphere, such as an aircraft, airship, balloon, or helicopter, or it may be a mobile device that moves outside the atmosphere, such as an artificial satellite. The mobile device may be a UAV (Unmanned Aerial Vehicle) such as a drone. Also, the terminal device 40 may be a wireless communication device mounted on a mobile device.

[0126] The terminal device 40 may be capable of communicating with multiple base stations 20 or multiple cells simultaneously. If one base station 20 supports a communication area via multiple cells (for example, pCell or sCell), communication between the base station 20 and the terminal device 40 can be achieved by bundling these multiple cells together using technologies such as carrier aggregation (CA), dual connectivity (DC), or multi-connectivity (MC). Alternatively, communication between the terminal device 40 and multiple base stations 20 can be achieved via cells of different base stations 20 using coordinated multi-point transmission and reception (CoMP) technology.

[0127] The terminal device 40 may be able to communicate with a plurality of base stations 20 or a plurality of cells. The terminal device 40 may also transmit and / or receive sensing signals to and from each of the plurality of base stations 20. The terminal device 40 may be configured to receive information about sensing signals (e.g., information about resources) from at least one of the plurality of base stations 20, or to receive information about sensing signals (e.g., information about resources) from each of the plurality of base stations 20. The terminal device 40 may also transmit and / or receive sensing signals in each of the plurality of cells. The terminal device 40 may be configured to receive information about sensing signals (e.g., information about resources) from at least one of the plurality of cells, or to receive information about sensing signals (e.g., information about resources) in each of the plurality of cells.

[0128] The terminal device 40 may be a relay terminal that relays communication to a remote terminal.

[0129] Multistatic sensing may be performed at the base station 20, the remote terminal, and the relay terminal. Specifically, sensing signals may be transmitted from both the base station 20 and the relay terminal. The remote terminal may receive sensing signals transmitted from both the base station 20 and the relay terminal.

[0130] The base station 20 and / or relay terminal may transmit to the relay terminal and / or remote terminal information regarding sensing signals transmitted and / or received by the relay terminal and / or remote terminal. In other words, the relay terminal and / or remote terminal may receive from the base station 20 and / or relay terminal information regarding sensing signals transmitted and / or received by the relay terminal and / or remote terminal.

[0131] Figure 6 shows the configuration of the terminal device 40 according to this embodiment. The terminal device 40 comprises a wireless communication unit 41, a storage unit 42, and a control unit 43. The configuration shown in Figure 6 is a functional configuration, and the hardware configuration may differ. Furthermore, the functions of the terminal device 40 may be distributed and implemented across multiple physically separated configurations.

[0132] Note that the terminal device 40 does not necessarily have all of the above-described or later-described configurations. Furthermore, the terminal device 40 may have configurations other than those described or later-described. The terminal device 40 may have a beamforming function. Furthermore, the terminal device 40 may be configured to acquire sensing data by performing sensing using a beam.

[0133] The wireless communication unit 41 is a signal processing unit for wireless communication with other wireless communication devices (for example, a base station 20, a relay station 30, or other terminal devices 40). The wireless communication unit 41 may be called a wireless transceiver or simply a transceiver. In this case, the wireless communication unit 41 may be a transceiver conforming to the standards specified in the 3GPP technical specifications (hereinafter referred to as a 3GPP transceiver). The 3GPP transceiver may be a 3G transceiver, a 4G (LTE) transceiver, a 5G (NR) transceiver, or a transceiver of a 5G or later generation. The wireless communication unit 41 is controlled, for example, by a control unit 43. The wireless communication unit 41 supports one or more wireless access schemes. The wireless communication unit 41 may support at least one of 4G (LTE), 5G (NR), B5G, and 6G. The wireless communication unit 41 may support 4G (LTE), 5G (NR), B5G, and 6G, as well as W-CDMA and cdma2000, etc. The wireless communication unit 41 may also support automatic retransmission technologies such as HARQ. Some or all of the processing performed by the wireless communication unit 41 may be performed by the control unit 43.

[0134] The wireless communication unit 41 includes a transmission processing unit 411, a reception processing unit 412, and an antenna 413. At least one of the transmission processing unit 411, the reception processing unit 412, and the antenna 413 may be considered as the wireless communication unit 41. The wireless communication unit 41 may include multiple transmission processing units 411, reception processing units 412, and antennas 413. If the wireless communication unit 41 supports multiple wireless access methods, each part of the wireless communication unit 41 may be configured separately for each wireless access method. The transmission processing unit 411 and the reception processing unit 412 may be configured separately for 4G (LTE), 5G (NR), B5G, and 6G. The antenna 413 may be composed of multiple antenna elements, for example, multiple patch antennas. The wireless communication unit 41 may have a beamforming function. For example, the wireless communication unit 41 may have a polarization beamforming function that uses vertical polarization (V polarization) and horizontal polarization (H polarization) (or a polarization beamforming function that uses dual polarization in polarization directions of 45 degrees and -45 degrees from the vertical). The wireless communication unit 41 may also transmit the sensing signals described above or below.

[0135] The memory unit 42 is a read / write storage device such as DRAM, SRAM, flash memory, or a hard disk.

[0136] The control unit 43 is a controller that controls each part of the terminal device 40. The control unit 43 controls the wireless communication unit 41 to perform wireless communication with other wireless communication devices (for example, a base station 20, a relay station 30, or another terminal device 40). The control unit 43 may be implemented by a processor such as a CPU or MPU. More specifically, the control unit 43 may be implemented by the processor executing various programs stored in the internal storage device of the terminal device 40 using RAM or the like as a working area. The control unit 43 may be implemented by an integrated circuit such as an ASIC or FPGA. CPU, MPU, ASIC, and FPGA can all be considered as controllers. The control unit 43 may be implemented by a GPU. CPU, MPU, ASIC, FPGA, and GPU can all be considered as controllers. The control unit 43 may be composed of multiple physically separated objects. For example, the control unit 43 may be composed of multiple semiconductor chips.

[0137] The control unit 43 comprises at least one block, which consists of a transmission control unit 431 and a reception control unit 432. The control unit 43 may comprise multiple blocks of each type, or it may comprise only one block of each type.

[0138] Each block constituting the control unit 43 (transmit control unit 431 to receive control unit 432) is a functional block that represents the function of the control unit 43. These functional blocks may be software blocks or hardware blocks. For example, each of the above-mentioned functional blocks may be a single software module implemented in software (including microprograms), or a single circuit block on a semiconductor chip (die). Of course, each functional block may also be a single processor or a single integrated circuit. The control unit 43 may be composed of functional units different from the above-mentioned functional blocks. The configuration method of the functional blocks is arbitrary. The operation of the control unit 43 may be the same as the operation of the control units (control unit 13, control unit 23, or control unit 33) of the management device 10, base station 20, or relay station 30.

[0139] <<3. Prerequisite Technology>> The configuration of the communication system 1 has been described above. Before describing the operation of the communication system 1 of this embodiment in detail, we will now explain the technology that is a prerequisite for describing the operation of the communication system 1 of this embodiment.

[0140] <3-1. Communication Points> First, let's explain communication points.

[0141] In conventional communication systems, communication control (e.g., initial access control and / or mobility control) was performed on a cell-by-cell basis. In other words, a conventional cell can be defined as a unit of transmission and reception points (communication nodes) for communication control.

[0142] However, in the future, in addition to the increasing complexity of communication topologies, it is anticipated that high-frequency bands such as millimeter waves or terahertz waves will be utilized. Therefore, future communication systems will require higher density units for communication control. In this embodiment, this unit of communication control is called a communication point, rather than a cell.

[0143] In this embodiment, a cell-free communication system is assumed as an example of a communication system that uses communication points. However, the point of this embodiment is not a change in the definition of a cell. The method of this embodiment can be applied to communication systems in which the definition of a cell remains the same as before. In other words, a cell-free communication system is one type of communication system to which the method of this embodiment can be applied, but the method of this embodiment can also be applied to communication systems other than cell-free communication systems. For example, the method of this embodiment can also be applied to a distributed MIMO system, a distributed antenna system, a multi-TRP system, or a multi-AP (Access Point) system.

[0144] <3-1-1. Definition of a Communication Point> A communication point is, for example, a wireless resource when a communication service is provided. A communication point may also be referred to as a communication node or node.

[0145] The communication point may be a conventional cell (a conventional planar cell formed by the base station 20 / relay station 30; hereinafter referred to as a classic cell). However, the communication point is not limited to a cell; for example, it may be a beam in beamforming (hereinafter also referred to as a beam cell) or a point in point forming (hereinafter also referred to as a point cell). Point forming will be described later.

[0146] In addition, communication points may be radio resources divided spatially, temporally, or frequency-wise. Multiple radio resources may be multiplexed spatially, temporally, or frequency-wise to form a communication point. A wireless communication device (for example, at least one of a base station 20, a relay station 30, and a terminal device 40) can identify each communication point by some means.

[0147] The communication point in this embodiment may be any of the following (A1) to (A15). The description of "communication point" in this embodiment can be replaced with a description indicating any of the following (A1) to (A15).

[0148] (A1) Cell (classic cell) (A2) Base station (e.g., gNB) (A3) Relay station (A4) TRP (Transmission and Reception Point) (A5) Antenna (A6) Antenna element (A7) Antenna port (A8) Set of antenna ports (A9) IAB (Integrated Access and Backhaul) node (A10) Relay UE (User Equipment) (A11) Beam in beamforming (beam cell) (A12) Point in point forming (point cell) (A13) CU (Central Unit) (A14) DU (Distributed Unit) (A15) RU (Radio Unit)

[0149] Furthermore, the communication point in this embodiment may be a cluster composed of multiple elements selected from (A1) to (A15) described above. The term "communication point" in this embodiment can be replaced with a term indicating this cluster.

[0150] Furthermore, the communication point in this embodiment may also be defined as (B1) to (B2) below, in addition to or instead of the above.

[0151] (B1) A node that transmits a synchronization signal and / or broadcast control information. For example, a communication point may be a unit (node) that the terminal device 40 can recognize as a destination for the first signal and / or the first broadcast information (e.g., SSB / SIB1) described later. Alternatively, for example, a communication point may be a unit (node) that the terminal device 40 can recognize as a destination for the second signal and / or the second broadcast information (e.g., SSB / SIBx) described later. x in SIBx is any integer of 1 or more. The terminal device 40 may recognize the communication point that transmits the first signal and / or the first broadcast information and the communication point that transmits the second signal and / or the second broadcast information as different communication points.

[0152] (B2) A unit defined based on QCL (Quasi-co-location). For example, a set of antenna ports having the same QCL may be recognized as a single communication point (cluster). A communication point may be defined or recognized by a TCI state. For example, a TRP, antenna, or antenna element defined or recognized by a single TCI state may be defined as a single communication point. Here, the TCI state is information about the QCL (Quasi-Co-Location) of a signal and / or channel.

[0153] Furthermore, the communication point in this embodiment does not need to be fixed and may be a mobile node. Moreover, the communication point in this embodiment does not need to be a terrestrial node and may be a non-terrestrial node. For example, the communication point in this embodiment may be a satellite, a drone, or an Unmanned Aerial Vehicle (UAV).

[0154] As described above, the base station 20 can be defined as a communication point. However, in this embodiment, the base station 20 does not necessarily have to be a communication point. For example, the base station 20 (or the functions of the base station 20 in this embodiment) may be a communication node capable of controlling the communication points connected to the base station 20. For example, the base station 20 in this embodiment may be a node on the core network CN side of the communication points.

[0155] Furthermore, the base station 20 can be implemented in various forms from a device perspective. For example, the base station 20 may be included in multiple communication points. The base station 20 may also control other communication points. Alternatively, for example, the base station 20 may be independent as a communication node between the core network CN and the communication points. Alternatively, for example, the base station 20 may be included in the core network CN.

[0156] Furthermore, the communication points in this embodiment may be clusters formed by clustering. The definitions of clustering and clusters are as follows, for example.

[0157] (Clustering) Clustering refers to configuring, for example, one or more communication nodes (or one or more candidate communication nodes) that are connected simultaneously. Information about the QCL can be configured for each of the clustered communication nodes. For example, suppose a communication node is an antenna port, and multiple communication nodes (i.e., antenna ports) are configured in one cluster. In this case, in that cluster, communication nodes with the same TRP will be indicated as having the same QCL, and communication nodes with different TRPs will be indicated as having different QCLs. In other words, a single cluster can have a mix of communication nodes with the same QCL and communication nodes with different QCLs.

[0158] (Cluster) A cluster refers to, for example, a set (list) of clustered communication nodes. For example, a cluster may be a set of communication nodes configured by RRC signaling. For example, a cluster may be a set of communication nodes configured by RRC signaling and also be a candidate for communication nodes that actually communicate. Note that communication nodes that actually communicate may be defined as subclusters.

[0159] Furthermore, the multiple entities constituting a cluster may be the communication points described above. In other words, a cluster may be composed of multiple communication points. In this case, the term "communication node" as described above or below can be replaced with "communication point".

[0160] A cluster may be referred to by a different name. Alternatively, a cluster may be defined by a different definition. For example, a cluster may be referred to / defined as shown in at least one of (C1) to (C6) below.

[0161] (C1) A node set cluster may be referred to as a node set.

[0162] (C2) Zone (Area) A zone is a spatial area that can be defined according to physical or virtual location. A given zone may contain multiple communication nodes. A zone may also be simply referred to as an area.

[0163] (C3) Cell set (cell) In particular, when the communication node is a cell (classic cell), the cluster of this embodiment may be called a cell set. A cell set may also be simply called a cell.

[0164] (C4) Antenna port set In particular, when the communication node is an antenna port, the cluster of this embodiment may be referred to as an antenna port set.

[0165] (C5) Beamset In particular, when the communication node is a beam (beam cell), the cluster of this embodiment may be referred to as a beamset.

[0166] (C6) Point set In particular, when the communication nodes are points (point cells), the cluster of this embodiment may be referred to as a point set.

[0167] Furthermore, each cluster may be assigned a unique identifier (cluster ID).

[0168] Furthermore, multiple clusters may be configured. In this case, the configured clusters may be referred to as a cluster set (cluster list). Note that a node belonging to one cluster may also belong to another cluster. In other words, a single node can belong to multiple clusters.

[0169] Clusters can be used by switching between them dynamically or quasi-statically.

[0170] <3-1-2. Specific Examples of Communication Systems> Next, specific examples of communication systems that use communication points will be described. As mentioned above, in this embodiment, a self-free communication system is assumed as an example of a communication system that uses communication points. However, the communication system 1 of this embodiment is not limited to a self-free communication system.

[0171] Figure 7 shows an example of the communication system 1 of this embodiment. The communication system 1 of this embodiment is a wireless communication system comprising a plurality of communication devices (for example, one or more terminal devices 40 and one or more base stations 20). In the following description, the base station 20 may be referred to as BS. Also, in the following description, the terminal device 40 may be referred to as UE.

[0172] The base station 20 includes one or more communication points P (for example, one or more communication antennas). Alternatively, the base station 20 is connected by wire or wireless to one or more communication points P (for example, one or more other base stations 20 and / or one or more relay stations 30). Note that the communication points P may be part of the configuration of the base station 20. For example, one or more communication points P may be one or more antennas of the base station 20.

[0173] In the example in Figure 7, base station 20 １ (BS shown in Figure 7) １ ) is communication point P １１ ~Communication points P １Ｎ It is connected to base station 20. １ (BS shown in Figure 7) １ ) is communication point P １１ ~Communication points P １Ｎ It is equipped with, where N is any integer greater than or equal to 1. Also, in the example in Figure 7, base station 20 ２ (BS shown in Figure 7) ２ ) is communication point P ２１ ~Communication points P ２Ｍ It is connected to base station 20. １ (BS shown in Figure 7) ２ ) is communication point P ２１ ~Communication points P ２Ｍ It includes the following: where M is any integer greater than or equal to 1.

[0174] Each communication point may be controlled by the connected base station 20. For example, communication point P １１ ~Communication points P １Ｎ is base station 20 １ It may be controlled by the communication point P. ２１ ~Communication points P ２Ｍ is base station 20 ２ It may be controlled by [something].

[0175] The terminal device 40 (UE shown in Figure 7) is wirelessly connected to one or more communication points P.

[0176] The communication points in this embodiment may operate standalone. In this embodiment, standalone operation refers to the operation in which one or more communication points perform initial access with one or more terminal devices 40 without requiring support or notification of information from other communication points. As described above, the communication points may be a single base station 20 or a cluster (for example, a group of multiple communication points).

[0177] Figures 8 and 9 illustrate standalone operation. For example, a communication point P where a terminal device 40 in an unconnected state (Idle mode / Inactive mode) operates standalone. １ In order to enable connection, the communication point of this embodiment may repeatedly (for example, periodically) transmit an initial access signal that conveys information for initial access. In the example of Figure 8, communication point P １ This is a single base station 20. In the example in Figure 9, the communication point P １ This is a cluster (a group consisting of a base station 20 and multiple communication points). Here, the information for initial access processing may be, for example, information for at least one of the following processes performed by the terminal device 40: recognition of the communication point, time-frequency synchronization, and transmission of the first uplink signal.

[0178] <3-1-3. Point Forming> As mentioned above, a communication point may also be a point in point forming. Point forming is a technique that concentrates power at a specific point by utilizing the phase difference of the near field. The following describes the power concentration technique at a specific point (point forming).

[0179] Figure 10 is a diagram illustrating power concentration technology (point forming) at a specific point. In conventional cellular mobile communication, a base station 20 (e.g., eNB (eNodeB), gNB (gNodeB), or RAN node (including EUTRAN, NGRAN)) concentrates power in a planar or beam-like manner to form a communication area (including femtocells, small cells, and large cells). In the example in Figure 10, the left diagram (classic cell) shows how the base station 20 forms a planar cell. The center diagram (beamforming) shows how the base station 20 forms a beam-shaped cell. As a result, the base station 20 provides communication to terminal equipment 40 (e.g., UE (User Equipment)). Next-generation cellular / cell-free communications require maximizing the efficiency of radio resource utilization (e.g., at least one of frequency, space, and time) to meet even more advanced demands (e.g., greater mass multi-connection (mMTC) and / or highly reliable, low-latency communication (URLLC)).

[0180] In beamforming, communication equipment increases power in a specific direction by coordinating the control of multiple antennas. Currently, the next technology after beamforming is attracting attention: a technology that forms cells at a point (a power concentration technology at a specific point). This is a technology that concentrates power at a single point in three dimensions, exceeding the spatial separation achieved by conventional beamforming, by coordinating the control of multiple transmitting devices (transmitting antennas, or devices with one or more transmitting antennas). In the example in Figure 10, the diagram on the right (point forming) shows how a base station forms a point-shaped cell (hereinafter also called a point cell). Hereafter, this technology will be referred to as point forming, but the terminology is not limited to this. For example, point forming may also be called beamfocusing or beamfocal.

[0181] Conventional beamforming methods could not multiplex beam directions, but point forming enables three-dimensional multiplexing. This allows for simultaneous communication with even more terminals. Furthermore, point forming can suppress interference to multiple terminals. As a result, improved overall system communication quality, reduced disconnection rates, and even greater multi-connection communication can be expected.

[0182] Point forming is a technique that maximizes received power at a specific point by coordinating the operation of multiple transmitting antennas so that the radio waves transmitted from each antenna combine in phase at that point, taking into account the phase difference of each wave. Outside of the specific point, the radio waves transmitted from the multiple transmitting antennas are received with random phases, and the received power is suppressed by averaging. This realizes point forming, which forms a cell at the specific point. In controlling the phase difference of the radio waves transmitted from the multiple transmitting antennas, the control device may, for example, control the initial phase of each transmitting antenna or control the amplitude of each transmitting antenna.

[0183] The multiple antennas (multiple transmission points) used for point forming may be one or more transmitting panels comprising multiple transmitting antennas (antenna elements). Figure 11 shows an example of point forming with a single antenna having multiple antenna elements. When radio waves are transmitted from a single transmitting panel having multiple transmitting antenna elements, near-field characteristics may be taken into consideration.

[0184] Figure 12 is a diagram illustrating the near-field and far-field. Conventionally, it was assumed that base stations would communicate with distant terminal devices such as smartphones. Therefore, conventional studies proceeded based on the assumption of a far-field as shown on the right side of Figure 12. However, future communication is expected to utilize even larger transmission panels. Therefore, it may be possible to enable communication that takes into account the phase difference, which is a characteristic of the near-field region. Point forming may be used in this near-field region. Figure 13 is a diagram showing the Fraunhofer distance (also called the Rayleigh distance), which is the boundary between the near-field and the far-field.

[0185] Here, we have shown an example of applying point forming in the near field, but point forming is possible in any environment where phase difference can be considered. Therefore, in an environment where many distributed antennas are around the receiving point, point forming can be implemented regardless of the Fraunhofer distance. Of course, if phase difference can be considered at the power concentration point, the communication device can also perform point forming using a single antenna with many antenna elements.

[0186] Figure 14 shows an example of point forming in a distributed antenna environment. In the example in Figure 14, the base station 20 has a control unit (CU (Central Unit) in the example in Figure 14) that controls multiple antennas and controls the transmitting antenna. In the example in Figure 14, one CU controls the transmitting antenna, but it is not necessary for only one CU to control it. Multiple elements (for example, DU (Distributed Unit), RAT (Radio Access Technology), and TRP (Transmission and Reception Point)) may work together. Also, in the example in Figure 14, the CU and the transmitting antenna are optically connected, but it is not necessarily optically connected. Note that each of the multiple transmitting points (transmitting antennas) may be one base station 20. Also, one or more base stations 20 may control multiple transmitting points (transmitting antennas).

[0187] Generally, the degree of power concentration in point forming varies depending on the number of transmitting points used during power concentration. There is a positive correlation between the number of transmitting points used to form one or more receiving points and the level of detailed power control. In other words, the more transmitting points there are, the more detailed power control becomes possible.

[0188] Furthermore, wireless communication related to point forming is not limited to wireless communication that utilizes a technology (power concentration technology) that concentrates power at a specific point by utilizing the phase difference of the near field. Wireless communication related to point forming may also be near-field communication. Here, near-field communication may be communication over a distance shorter than the Fraunhofer distance, which is determined by the frequency band and the aperture length of the transmitting panel.

[0189] Furthermore, in the example described above, one base station 20 performed the point forming process. However, multiple base stations 20 may cooperate to perform the point forming process. For example, multiple base stations 20 may form a point cell by coordinating the control of their respective transmitting antennas with other base stations 20. The base stations 20 may also cooperate with the relay station 30.

[0190] <3-2. Initial Access Control> The communication points have been described above, but before describing the operation of the communication system 1 of this embodiment in detail, the initial access control (also called the initial access procedure, initial access method, initial access processing, or initial connection processing) will be described.

[0191] <3-2-1. Basic Procedure> First, as a basic procedure for initial access control, an example of the procedure for connecting the terminal device 40 to the base station 20 will be explained. Note that the terms "base station 20" and / or "cell" used in the following explanation can be replaced with "communication point".

[0192] Initial access control is a process that transitions the wireless connection state of the terminal device 40 from an unconnected state to a connected state. In the following description, initial access control may be referred to as the initial access procedure or initial access process.

[0193] Here, the unconnected state refers to, for example, RRC_IDLE and / or RRC_INACTIVE. RRC_IDLE is an idle state in which the terminal device 40 is not connected to any cell, and is also called Idle mode. RRC_INACTIVE is a wireless connection state that indicates an inactive state newly defined in NR, and is also called Inactive mode. In RRC_INACTIVE, the RRC connection itself is not established between the terminal device 40 and the base station 20, but the terminal device 40 and the base station 20 may maintain the states they each hold for some UE contexts. The terminal device 40 and the base station 20 may use the UE contexts they have held to expedite the transition of the terminal device 40 back to the Connected state. Note that the unconnected state may include Lightning mode. The connected state is, for example, RRC_CONNECTED. RRC_CONNECTED is a connected state in which the terminal device 40 has established a connection with a specific cell (e.g., Primary Cell), and is also called CONNECTED mode.

[0194] Figure 15 is a sequence diagram showing an example of the initial access process. The initial access process will be explained below with reference to Figure 15.

[0195] An unconnected terminal device 40 performs a cell selection procedure (cell search). The cell selection procedure (cell search) is a procedure for the UE (User Equipment) to detect the PCI (Physical Cell ID) of the cell and obtain time and frequency synchronization. The cell search in this embodiment includes the steps of detecting the synchronization signal and decoding the PBCH (Physical Broadcast Channel). First, the base station 20 transmits an SSB (SS / PBCH block) and / or a PBCH (Physical Broadcast Channel) (step S11). The SSB is a block (signal / information / channel) consisting of a PBCH, a PSS (Primary Synchronization Signal), and a SSS (Secondary Synchronization Signal). The terminal device 40 detects the cell's synchronization signal (SS: Synchronization Signal) (step S12).

[0196] The terminal device 40 synchronizes the cell and the downlink based on the detected synchronization signal. After the downlink synchronization is established, the terminal device 40 attempts to decode the PBCH and obtains the MIB (Master Information Block), which is part of the system information (step S13).

[0197] System information is information that notifies the settings of the cell transmitting the system information. System information may be common to all terminal devices 40 belonging to the cell. System information may also be specific to the cell. System information includes, for example, information regarding access to the cell, information regarding cell selection, information regarding other RATs and other systems. System information includes MIB (Master Information Block) and SIB (System Information Block). MIB is information necessary to receive SIBs, etc., and is information of a fixed payload size notified by PBCH. MIB includes a part of the system frame number, information on the subcarrier spacing of predetermined information (e.g., SIB1, Msg.2 / Msg.4 for initial connection, paging, and broadcast SI messages), subcarrier offset information, DMRS type A location information, PDCCH settings for at least SIB1, cell connection prohibited (cell barred) information, in-frequency reselection information, etc. SIB is system information other than MIB and is notified by PDSCH.

[0198] System information can be classified into three categories: first system information, second system information, and third system information. The first and second system information include information related to cell access, information related to the acquisition of other system information, and information related to cell selection. The information contained in the MIB (Minimum Information Bag) constitutes the first system information. The information contained in SIB1 (Single Information Bag) constitutes the second system information (e.g., Remaining Minimum SI). The remaining system information constitutes the third system information (e.g., Other SI).

[0199] In NR, system information is also broadcast from the NR cell. The physical channel carrying the system information may be transmitted via a slot or a minislot. A minislot is defined as having fewer symbols than a slot. By transmitting the physical channel carrying the system information via a minislot, the time required for beam sweeping is reduced, thereby decreasing overhead. In the case of NR, the first system information is transmitted via the NR-PBCH, and the second system information is transmitted via a physical channel different from the NR-PBCH.

[0200] The terminal device 40 acquires second system information based on the MIB (i.e., first system information) (step S14). As described above, the second system information consists of SIB1 and SIB2.

[0201] SIB1 contains cell access restriction information and scheduling information for system information other than SIB1. If it is NR, SIB1 includes information about cell selection (e.g., cellSelectionInfo), information related to cell access (e.g., cellAccessRelatedInfo), information about connection establishment failure control (e.g., connEstFailureControl), scheduling information for system information other than SIB1 (e.g., si-SchedulingInfo), serving cell settings, etc. Serving cell settings include cell-specific parameters, such as downlink settings, uplink settings, and TDD setting information. Uplink settings include RACH settings, etc. If it is LTE, SIB1 includes cell access information, cell selection information, maximum uplink transmit power information, TDD setting information, system information period, system information mapping information, and SI (System Information) window length, etc.

[0202] Furthermore, if it is NR, SIB2 includes cell reselection information (e.g., cellReselectionInfoCommon) and cell reselection serving frequency information (e.g., cellReselectionServingFreqInfo). If it is LTE, SIB2 includes connection prohibition information, cell-common radio resource configuration information (radioResourceConfigCommon), uplink carrier information, etc. The cell-common radio resource configuration information includes cell-common PRACH (Physical Random Access Channel) and RACH (Random Access Channel) configuration information.

[0203] Furthermore, if the terminal device 40 fails to obtain the system information necessary to establish a link, the terminal device 40 determines that access to that cell is prohibited. For example, if it fails to obtain the first system information, the terminal device 40 determines that access to that cell is prohibited. In this case, the terminal device 40 terminates the initial access process.

[0204] If system information is obtained, the terminal device 40 executes a Random Access Procedure based on the first system information and / or the second system information (steps S15 to S18). The Random Access Procedure is sometimes referred to as the RACH Procedure (Random Access Channel Procedure) or the RA Procedure (RA Procedure).

[0205] The random access procedure includes the steps of sending a random access preamble (step S15), receiving a random access response (step S16), sending Message 3 (step S17), and receiving contention resolution (step S18).

[0206] First, terminal device 40 selects a predetermined PRACH (Physical Random Access Channel) preamble and transmits it to base station 20 (step S15). Next, terminal device 40 receives a PDSCH (Physical Downlink Shared Channel) containing a random access response corresponding to the PRACH preamble (step S16). Next, terminal device 40 transmits a PUSCH containing message 3 using the resources scheduled by the random access response grant included in the random access response (step S17). Finally, terminal device 40 receives a PDSCH containing collision resolution corresponding to the PUSCH (step S18).

[0207] Message 3 includes an RRC (Radio Resource Control) message requesting an RRC connection. Conflict resolution includes an RRC message for RRC connection setup. When terminal device 40 receives the RRC message for RRC connection setup, it performs an RRC connection operation and transitions from the RRC idle state to the RRC connected state. After transitioning to the RRC connected state, terminal device 40 sends an RRC message to base station 20 indicating completion of RRC connection setup. Through this series of operations, terminal device 40 can connect with base station 20.

[0208] The random access preamble is sometimes referred to as message 1, the random access response as message 2, the collision resolution message as message 4, and the RRC connection setup completion message as message 5.

[0209] After all steps of the random access procedure are completed, the terminal device 40 can transition to a state where it is connected to the cell (connected state).

[0210] The random access procedure shown in Figure 15 is sometimes referred to as a four-step random access procedure (four-step RACH procedure). On the other hand, a random access procedure in which the terminal device 40 transmits a message 3 along with the transmission of a random access preamble, and the base station 20 transmits a random access response and contention resolution in response, is sometimes referred to as a two-step random access procedure (two-step RACH procedure).

[0211] <3-2-2. Random Access Procedures> Next, random access procedures will be explained in detail.

[0212] Random access procedures are performed for purposes such as "RRC connection setup" from an idle state to a connected (or inactive) state, and "state transition requests" from an inactive state to a connected state. Random access procedures are also used for "scheduling requests" to request resources for uplink data transmission, and "timing advance adjustments" to adjust uplink synchronization. In addition, random access procedures are performed in cases such as "on-demand SI requests" to request system information that has not been transmitted, "beam recovery" to restore a broken beam connection, and "handover" to switch connected cells.

[0213] "RRC connection setup" is an operation performed when the terminal device 40 connects to the base station 20 in response to traffic generation or other events. Specifically, it is an operation in which the base station 20 passes connection information (e.g., UE context) to the terminal device 40. The UE context is managed by predetermined communication device identification information (e.g., C-RNTI) instructed by the base station 20. After completing this operation, the terminal device 40 transitions from an idle state to an inactive state, or from an idle state to a connected state.

[0214] A "state transition request" is an operation in which the terminal device 40 requests a state transition from an inactive state to a connected state in response to the occurrence of traffic or other events. By transitioning to the connected state, the terminal device 40 can send and receive unicast data with the base station 20.

[0215] A "scheduling request" is an operation in which the terminal device 40 requests resources for uplink data transmission in response to traffic generation or other events. After successfully receiving this scheduling request, the base station 20 allocates PUSCH resources to the communication device. Note that scheduling requests can also be made via PUCCH.

[0216] "Timing advance adjustment" is an operation to adjust for the frame errors between the downlink and uplink caused by propagation delay. The terminal device 40 transmits PRACH (Physical Random Access Channel) at the adjusted timing in the downlink frame. This allows the base station 20 to recognize the propagation delay with the terminal device 40 and to instruct the terminal device 40 of the timing advance value in a message 2 or the like.

[0217] An "on-demand SI request" is an operation that requests the base station 20 to transmit system information when the terminal device 40 needs system information that has not been transmitted for reasons such as overhead of system information.

[0218] "Beam recovery" is an operation that requests recovery if the communication quality deteriorates after the beam has been established due to the movement of the terminal device 40 or the interruption of the communication path by other objects. Upon receiving this request, the base station 20 attempts to connect with the terminal device 40 using a different beam.

[0219] "Handover" is the operation of switching the connection from the cell to which the terminal device 40 is connected (serving cell) to an adjacent cell (neighbor cell) due to changes in the radio wave environment, such as the movement of the terminal device 40. When the terminal device 40 receives a handover command from the base station 20, it requests a connection to the neighbor cell specified by the handover command.

[0220] Random access procedures include contention-based random access procedures and non-contention-based random access procedures.

[0221] The random access procedure described below assumes that the RAT supported by communication system 1 is LTE. However, the random access procedure described below is also applicable when the RAT supported by communication system 1 is not LTE. For example, the random access procedure described below is also applicable when the RAT supported by communication system 1 is 5G, B5G, 6G, or a later generation RAT.

[0222] The following describes collision-based random access procedures and non-collision-based random access procedures in detail.

[0223] <Collision-Based Random Access Procedures> First, let's explain collision-based random access procedures.

[0224] A collision-based random access procedure is a random access procedure initiated by the terminal device 40. Figure 16 shows a diagram of the collision-based random access procedure. As shown in Figure 16, the collision-based random access procedure is a four-step procedure that begins with the transmission of a random access preamble from the terminal device 40. The collision-based random access procedure includes the steps of transmitting a random access preamble (Message 1), receiving a random access response (Message 2), transmitting a message (Message 3), and receiving a conflict resolution message (Message 4).

[0225] First, the terminal device 40 randomly selects a preamble sequence to use from a predetermined set of preamble sequences. Then, the terminal device 40 sends a message containing the selected preamble sequence (Message 1: Random Access Preamble) to the connected base station 20 (step S21). The random access preamble is transmitted using PRACH.

[0226] When base station 20 receives a random access preamble, it sends a random access response (Message 2) to terminal device 40. This random access response is transmitted, for example, using a PDSCH. Terminal device 40 receives the random access response (Message 2) sent from base station 20 (step S22). The random access response includes one or more random access preambles that base station 20 received, and the UL (Uplink) resource (hereinafter referred to as the uplink grant) corresponding to the random access preamble. The random access response also includes TC-RNTI (Temporary Cell Radio Network Temporary Identifier), which is a unique identifier for terminal device 40 that base station 20 has temporarily assigned to terminal device 40.

[0227] When terminal device 40 receives a random access response from base station 20, it determines whether the received information includes the random access preamble transmitted in step S21. If the random access preamble is included, terminal device 40 extracts the uplink grant corresponding to the random access preamble transmitted in step S21 from among the uplink grants included in the random access response. Then, terminal device 40 uses the resources scheduled by the extracted uplink grant to transmit a UL message (Message 3: Scheduled Transmission) (step S23). The transmission of message (Message 3) is performed using PUSCH. Message (Message 3) includes an RRC message for RRC (Radio Resource Control) connection request. Message (Message 3) also includes the identifier of terminal device 40.

[0228] In a collision-based random access procedure, a random access preamble randomly selected by terminal device 40 is used in the procedure. Therefore, it is possible that when terminal device 40 transmits a random access preamble, another terminal device 40 may simultaneously transmit the same random access preamble to the base station 20. In this case, the base station 20 recognizes which terminal devices have a preamble conflict by receiving the identifier transmitted by terminal device 40 in step S23 and resolves the conflict. The base station 20 sends a contention resolution message (Message 4) to the terminal device 40 selected by the conflict resolution. The contention resolution message (Message 4) includes the identifier transmitted by terminal device 40 in step S23. The contention resolution message (Message 4) also includes an RRC message for RRC connection setup. Terminal device 40 receives the contention resolution message (Message 4) transmitted from the base station 20 (step S24).

[0229] The terminal device 40 compares the identifier transmitted in step S23 with the identifier received in step S24. If the identifiers do not match, the terminal device 40 restarts the random access procedure from step S21. If the identifiers match, the terminal device 40 performs an RRC connection operation and transitions from the idle state (RRC_IDLE) to the connected state (RRC_CONNECTED). The terminal device 40 uses the TC-RNTI acquired in step S22 as the C-RNTI (Cell Radio Network Temporary Identifier) ​​for subsequent communications. After transitioning to the connected state, the terminal device 40 sends an RRC message to the base station 20 indicating that the RRC connection setup is complete. This message indicating the completion of the RRC connection setup is also called message 5. Through this series of operations, the terminal device 40 connects with the base station 20.

[0230] Note that the collision-based random access procedure shown in Figure 16 is a four-step random access procedure (4-step RACH). However, the communication system 1 can also support a two-step random access procedure (2-step RACH) as a collision-based random access procedure. For example, the terminal device 40 transmits the message shown in step S23 (Message 3) along with the random access preamble. The base station 20 then transmits a random access response (Message 2) and a conflict resolution (Message 4) in response. Since the random access procedure is completed in two steps, the terminal device 40 can quickly connect to the base station 20.

[0231] Note that Message 1 may be written as "Msg1" or "Msg.1". Message 2 may be written as "Msg2" or "Msg.2". Message 3 may be written as "Msg3" or "Msg.3". Message 4 may be written as "Msg4" or "Msg.4".

[0232] <Non-collision-based random access procedures> Next, we will explain non-collision-based random access procedures.

[0233] The non-collision-based random access procedure is a random access procedure initiated by the base station 20. Figure 17 shows a diagram of the non-collision-based random access procedure. The non-collision-based random access procedure is a three-step procedure that begins with the transmission of a random access preamble assignment from the base station 20. The non-collision-based random access procedure includes the steps of receiving a random access preamble assignment (Message 0), transmitting a random access preamble (Message 1), and receiving a random access response (Message 2).

[0234] In collision-based random access procedures, terminal device 40 randomly selects a preamble sequence. However, in non-collision-based random access procedures, base station 20 assigns a specific random access preamble to terminal device 40. Terminal device 40 receives a random access preamble assignment (Message 0: RA Preamble Assignment) from base station 20 (step S31).

[0235] The terminal device 40 performs random access to the base station 20 using the random access preamble assigned in step S31. That is, the terminal device 40 transmits the assigned random access preamble (Message 1: Random Access Preamble) to the base station 20 using PRACH (step S32).

[0236] The base station 20 receives a random access preamble (Message 1) from the terminal device 40. Then, the base station 20 sends a random access response (Message 2) to the terminal device 40 for the random access preamble (step S33). The random access response includes, for example, information about the uplink grant corresponding to the received random access preamble. When the terminal device 40 receives the random access response (Message 2), it performs an RRC connection operation and transitions from the idle state (RRC_IDLE) to the connected state (RRC_CONNECTED).

[0237] Thus, in a collision-free random access procedure, the base station 20 schedules the random access preamble, making preamble collisions less likely.

[0238] Note that Message 0 may be written as "Msg0" or "Msg.0". Message 1 may be written as "Msg1" or "Msg.1". Message 2 may be written as "Msg2" or "Msg.2".

[0239] <3-2-3. Random Access Procedure for NR> The above describes the random access procedure assuming that the RAT supported by communication system 1 is LTE. Note that the above random access procedure is also applicable to RATs other than LTE. Below, as an example, the random access procedure assuming that the RAT supported by communication system 1 is NR (5G) will be described in detail.

[0240] <Random Access Procedure for NR> The following description details each of the four steps related to Message 1 to Message 4 shown in Figure 16 or Figure 17. The step for Message 1 corresponds to step S21 shown in Figure 16 or step S32 shown in Figure 17. The step for Message 2 corresponds to step S22 shown in Figure 16 or step S33 shown in Figure 17. The step for Message 3 corresponds to step S23 shown in Figure 16. The step for Message 4 corresponds to step S24 shown in Figure 16.

[0241] NR Random Access Preamble (Message 1) In NR, PRACH is called NR-PRACH (NR Physical Random Access Channel). NR-PRACH is constructed using Zadoff-Chu sequences. In NR, multiple preamble formats are defined as the format of NR-PRACH. The preamble format is defined by a combination of parameters such as the subcarrier spacing of the PRACH, transmission bandwidth, sequence length, number of symbols used for transmission, transmission repetitions, CP (Cyclic Prefix) length, and guard period length. The types of NR-PRACH preamble sequences are numbered. The number of the type of preamble sequence is called the preamble index.

[0242] In NR, settings related to NR-PRACH are configured for idle terminal devices 40 based on system information. Furthermore, settings related to NR-PRACH are configured for connected terminal devices 40 via dedicated RRC signaling.

[0243] Terminal device 40 transmits NR-PRACH using a physical resource (NR-PRACH Occasion) that can transmit NR-PRACH. The physical resource is indicated by the settings related to NR-PRACH. Terminal device 40 selects one of the physical resources and transmits NR-PRACH. Furthermore, if terminal device 40 is connected, terminal device 40 transmits NR-PRACH using an NR-PRACH resource. An NR-PRACH resource is a combination of the NR-PRACH preamble and its physical resource. Base station 20 can instruct terminal device 40 on the NR-PRACH resource.

[0244] NR-PRACH is also transmitted when the random access procedure fails. When retransmitting NR-PRACH, terminal device 40 waits for a waiting period calculated from the backoff value (backoff indicator, BI) before transmitting NR-PRACH. The backoff value may vary depending on the terminal category of terminal device 40 and the priority of the traffic that occurred. In this case, multiple backoff values ​​are notified, and terminal device 40 selects the backoff value to use according to priority. Also, when retransmitting NR-PRACH, terminal device 40 increases the transmission power of NR-PRACH compared to the initial transmission. This procedure is called power ramping.

[0245] NR Random Access Response (Message 2) NR random access responses are transmitted using the NR-PDSCH (NR Physical Downlink Shared Channel). The NR-PDSCH containing the random access response is scheduled by the NR-PDCCH (NR Physical Downlink Control Channel), which has its CRC (Cyclic Redundancy Check) scrambled by RA-RNTI. The NR-PDCCH is transmitted in the CORESET (Control Resource Set). The NR-PDCCH with its CRC scrambled by RA-RNTI is placed in the CSS (Common Search Space) of the Type1-PDCCH CSS set. The value of RA-RNTI (Random Access Radio Network Temporary Identifier) ​​is determined based on the transmission resource of the NR-PRACH corresponding to that random access response. The transmission resources for NR-PRACH are, for example, time resources (slots or subframes) and frequency resources (resource blocks). NR-PDCCH may be placed in a search space associated with an NR-PRACH linked to a random access response. Specifically, the search space where NR-PDCCH is placed is configured in association with the NR-PRACH preamble and / or the physical resource from which the NR-PRACH was transmitted. The search space where NR-PDCCH is placed is configured in association with the preamble index and / or the index of the physical resource. NR-PDCCH resides in NR-SS (NR Synchronization signal) and QCL (Quasi co-located).

[0246] The NR random access response contains MAC (Medium Access Control) information. The NR random access response includes at least the uplink grant for sending NR message 3, the timing advance value used to adjust uplink frame synchronization, and the TC-RNTI value. The NR random access response also includes the PRACH index used for the NR-PRACH transmission corresponding to that random access response. Furthermore, the NR random access response includes information about the backoff used to wait for PRACH transmission.

[0247] The base station 20 transmits a random access response in NR-PDSCH format. The terminal device 40 determines whether the transmission of the random access preamble was successful based on the information contained in the random access response. If it determines that the transmission of the random access preamble was successful, the terminal device 40 performs the transmission process of NR message 3 according to the information contained in the random access response. On the other hand, if the transmission of the random access preamble fails, the terminal device 40 determines that the random access procedure has failed and performs the retransmission process of NR-PRACH.

[0248] Furthermore, the NR's random access response may include multiple uplink grants for sending the NR's message 3. The terminal device 40 can select one resource from the multiple uplink grants to send message 3. This mitigates collisions in sending the NR's message 3 when different terminal devices 40 receive the same NR's random access response. As a result, the communication system 1 can provide a more stable random access procedure.

[0249] NR Message 3 NR Message 3 is transmitted via NR-PUSCH (NR Physical Uplink Shared Channel). NR-PUSCH is transmitted using the resources indicated by the random access response. NR Message 3 contains an RRC connection request message. The format of NR-PUSCH is indicated by parameters included in the system information. For example, parameters determine whether to use OFDM (Orthogonal Frequency Division Multiplexing) or DFT-s-OFDM (Discrete Fourier Transform Spread OFDM) as the format for NR-PUSCH.

[0250] If NR message 3 is successfully received, base station 20 proceeds to the conflict resolution (Message 4) transmission process. On the other hand, if NR message 3 is not successfully received, base station 20 attempts to receive NR message 3 again for at least a predetermined period of time.

[0251] Another example of instructions for retransmitting message 3 and the transmission resources involved is the instruction by NR-PDCCH used for instructing the retransmission of message 3. This NR-PDCCH is an uplink grant. The DCI (Downlink Control Information) of this NR-PDCCH instructs the resources for retransmitting message 3. The terminal device 40 retransmits message 3 based on the instructions from the uplink grant.

[0252] If the NR conflict resolution is not successfully received within a predetermined period, the terminal device 40 considers the random access procedure to have failed and performs the NR-PRACH retransmission process. The transmission beam of the terminal device 40 used to retransmit the NR message 3 may be different from the transmission beam of the terminal device 40 used to initially transmit the message 3. If neither the NR conflict resolution nor the instruction to retransmit message 3 is received within the predetermined period, the terminal device 40 considers the random access procedure to have failed and performs the NR-PRACH retransmission process. This predetermined period is set, for example, by system information.

[0253] NR Conflict Resolution (Message 4) NR conflict resolution is transmitted using NR-PDSCH. NR-PDSCH containing conflict resolution is scheduled by NR-PDCCH with CRC scrambled by TC-RNTI or C-RNTI. NR-PDCCH with CRC scrambled by TC-RNTI is placed in the CSS of Type1-PDCCH CSS set. NR-PDCCH may also be placed in USS (User equipment specific Search Space). NR-PDCCH may also be placed in other CSSs.

[0254] If terminal device 40 successfully receives the NR-PDSCH including the conflict resolution, it sends an acknowledgment (ACK) to base station 20. Thereafter, terminal device 40 considers the random access procedure to have been successful and transitions to the connected state (RRC_CONNECTED). On the other hand, if base station 20 receives a negative acknowledgment (NACK) for the NR-PDSCH from terminal device 40, or if there is no response, base station 20 retransmits the NR-PDSCH including the conflict resolution. If terminal device 40 fails to receive the NR conflict resolution (Message 4) within a predetermined period, it considers the random access procedure to have failed and retransmits the random access preamble (Message 1).

[0255] <NR's Two-Step Random Access Procedure> Next, an example of NR's two-step random access procedure (hereinafter referred to as the two-step random access procedure) is shown.

[0256] Figure 18 shows a two-step random access procedure. The two-step random access procedure consists of two steps: message A (step S41) and message B (step S42). For example, message A includes message 1 (preamble) and message 3 of a conventional four-step random access procedure (4-STEP RACH procedure), and message B includes message 2 and message 4 of a conventional four-step random access procedure. Also, for example, message A consists of a preamble (also called PRACH) and PUSCH, and message B consists of PDSCH.

[0257] By using a two-step random access procedure, it becomes possible to complete the random access procedure with lower latency compared to the conventional four-step random access procedure.

[0258] The preamble and PUSCH included in message A may be configured in conjunction with their respective transmission resources, or they may be configured as independent resources.

[0259] When transmission resources are associated and configured, for example, when the transmission resource for the preamble is determined, a unique or multiple candidate transmission resource for PUSCH is determined. As an example, the time and frequency offset between the PRACH occasion preamble and the PUSCH occasion is defined by a single value. As another example, the time and frequency offset between the PRACH occasion preamble and the PUSCH occasion may be defined by different values ​​for each preamble. The offset values ​​may be determined by the specification, or the base station 20 may set them quasi-statically. As an example of the time and frequency offset values, they may be defined by a predetermined frequency. For example, in an unlicensed band (e.g., 5GHz band, band 45), the time offset value can be set to 0 or a value close to 0. This makes it possible to omit LBT (Listen Before Talk) before transmitting PUSCH.

[0260] On the other hand, if configured with independent resources, the transmission resources for the preamble and PUSCH may be determined by the specifications, the resources may be configured quasi-statically by the base station 20, or the resources may be determined from other information. Other information may include, for example, slot format information (e.g., Slot Format Indicator), BWP (Band Width Part) information, preamble transmission resource information, slot index, and resource block index. Also, if configured with independent resources, the association between the preamble and PUSCH constituting a single message A may be notified to the base station 20 by the payload of the PUSCH or the UCI contained in the PUSCH, or by the transmission physical parameters of the PUSCH (e.g., the scramble sequence of the PUSCH, the DMRS sequence and / or pattern, or the transmission antenna port of the PUSCH).

[0261] Furthermore, the method for configuring the preamble and PUSCH transmission resources may be switched between being configured as linked resources and being configured as independent resources. For example, the independent resource configuration may apply to licensed bands, while the linked resource configuration may apply to unlicensed bands.

[0262] The above describes a random access procedure assuming that the RAT supported by communication system 1 is NR. Note that the above random access procedure is also applicable to RATs other than NR (e.g., 5G, B5G, or 6G, or later generations of RATs). Furthermore, the above random access procedure is also applicable to cell-free communication.

[0263] <3-2-4. Initial Access Control in Self-Free Communication> The initial access control (initial access processing) described above is also applicable to self-free communication. The initial access control (initial access processing) in self-free communication will be explained below.

[0264] In initial access control (initial access processing), the terminal device 40 receives at least a first signal, a first broadcast information, a second signal, and a second broadcast information from the communication point. Based on these signals and information, the terminal device 40 performs initial access processing.

[0265] The first signal, the first broadcast information, the second signal, and the second broadcast information may be signals / information used in conventional standards (e.g., NR and / or LTE) (e.g., the first initial access signal described later), or they may be signals / information with a different configuration from signals / information used in conventional standards (e.g., NR and / or LTE) (e.g., the second initial access signal described later).

[0266] The first signal, the first broadcast information, the second signal, and the second broadcast information will be explained below. Note that the following information (the first signal, the first broadcast information, the second signal, and the second broadcast information) is applicable to communications other than cell-free communications. Furthermore, the following information (the first signal, the first broadcast information, and the second signal) is also applicable to conventional cellular communications (e.g., 4G and / or 5G).

[0267] <First Signal> First, let me explain the first signal.

[0268] The first signal may be a predetermined signal detected by the terminal device 40 before receiving the first broadcast information. Alternatively, the first signal may be a signal for the terminal device 40 to perform at least one of the following: time synchronization, frequency synchronization, cell ID recognition, recognition of the resource for the first broadcast information, and reception processing of the first broadcast information.

[0269] The first signal may be a synchronization signal having the same function, purpose, and configuration as, for example, the PSS and / or SSS in 5G (NR) and 4G (LTE). Alternatively, the first signal may be a synchronization signal having the same function, purpose, and configuration as, for example, the PSS and / or SSS in 5G (NR) and 4G (LTE). Of course, the first signal is not limited to these signals.

[0270] The first signal is transmitted from a predetermined communication point among one or more communication points. In this case, the first signal may be transmitted from multiple communication points. For example, the first signal may be transmitted from all communication points connected to a base station 20.

[0271] <First piece of information> Next, I will explain the first piece of information.

[0272] The first broadcast information is information that enables the terminal device 40 to perform at least one of the following: perform an initial access and receive a second signal. The first broadcast information does not necessarily have to be transmitted in a single transmission unit, a single resource, or a single channel. The first broadcast information may be transmitted in multiple transmission units, multiple resources, or multiple channels.

[0273] The first broadcast information is, for example, information (or channel) with the same function, purpose, and configuration as a PBCH in 5G. Alternatively, the first broadcast information is, for example, information (or channel) with the same function, purpose, and configuration as a PBCH in 5G. Alternatively, the first broadcast information is information (or channel) with the same function, purpose, and configuration as MIB and / or SIB in 5G (NR) and 4G (LTE). Alternatively, the first broadcast information is, for example, information (or channel) with the same function, purpose, and configuration as MIB and / or SIB in 5G (NR) and 4G (LTE). Of course, the first broadcast information is not limited to this information (or channel).

[0274] (Information included in the first broadcast information) The first broadcast information may include at least one of the following: information relating to the second signal and information relating to the initial access.

[0275] (1) Information concerning the second signal Information concerning the second signal is information necessary for the terminal device 40 to receive the second signal. Information concerning the second signal may be a list of one or more second signals that the terminal device 40 may receive or should receive. In this case, the second signals included in the list may be all of the second signals transmitted / managed / controlled by the communication point that transmits the first signal and / or the first broadcast information. Alternatively, the second signals included in the list may be a part of the second signals transmitted / managed / controlled by the communication point that transmits the first signal and / or the first broadcast information. In this case, the second signals included in the list may be determined according to the location of the terminal device 40, etc.

[0276] The information regarding the second signal may include, for example, at least one of the pieces of information shown in (D1) to (D4) below.

[0277] (D1) The number of signals that the terminal device 40 may receive or should receive. (D2) Time and frequency resource information. (D3) If the second signal is code-divided multiplexed, information about the code (e.g., code index). (D4) If a scramble code is superimposed on the second signal (e.g., if the second signal is generated based on a scramble code), information about that scramble code.

[0278] Furthermore, the information regarding the second signal may include a list of communication points that can be combined.

[0279] (2) Information regarding initial access Information regarding initial access may be information necessary for the terminal device 40 to perform initial access processing (initial access control) to the communication point. Here, the communication point may be a predetermined base station 20, a predetermined communication point connected to the predetermined base station 20, or a core network controlling the predetermined base station 20. The communication point may also be a communication node associated with (determined based on) the predetermined base station 20, a predetermined communication point, or a predetermined core network.

[0280] Furthermore, information regarding the initial access may be transmitted from each communication point as a second piece of information.

[0281] Information regarding initial access may include, for example, at least one of the following pieces of information: (E1) to (E3).

[0282] (E1) Information necessary for transmitting, selecting, or determining the random access channel (msg1). For example, the information regarding initial access may include information necessary for selecting or determining the random access channel. For example, the information regarding initial access may include information indicating the selectable range of random access preambles to be transmitted on the random access channel. The information regarding initial access may also include information regarding time and frequency resources for transmitting the random access channel.

[0283] (E2) Information necessary for receiving the random access response (msg2). For example, information regarding the initial access may include information necessary for recognizing or detecting the random access response.

[0284] (E3) Information regarding PUSCH (msg3) For example, information regarding initial access may include information regarding information to be transmitted by PUSCH. For example, information regarding initial access may include information regarding the selected communication point and / or information regarding the communication quality for one or more communication points.

[0285] (Other) The first broadcast information is transmitted from a predetermined communication point among one or more communication points. In this case, the first broadcast information may be transmitted from multiple communication points. For example, the first broadcast information may be transmitted from all communication points connected to a base station 20.

[0286] Furthermore, the first broadcast information may be transmitted from the same communication point as the first signal. That is, the QCI (QoS Class Identifier) ​​of the first broadcast information may be recognized as being the same as the QCI of the first signal. For example, when the terminal device 40 demodulates and / or decodes the first broadcast information, it may do so using at least a part of the propagation path characteristics of the first signal.

[0287] The first notification information may be transmitted from a different communication point than the first signal.

[0288] <Second Signal> Next, I will explain the second signal.

[0289] The second signal may be at least one of the following signals (F1) to (F4). Of course, the second signal is not limited to these signals.

[0290] (F1) Reference signal transmitted from a communication point For example, the second signal may be a reference signal transmitted from a communication point. For example, the second signal may be a known reference signal that the terminal device 40 can recognize as being transmitted from a predetermined communication point. Here, the QCI of the second signal may be different from the QCI of the first broadcast information and / or the QCI of the first signal.

[0291] (F2) A signal for measuring the communication quality of a communication point The second signal may be a signal for measuring (detecting, recognizing, or actually measuring) the communication quality of a communication point. For example, the second signal may be a known signal used in initial access control to select a communication point and / or report on the communication quality.

[0292] Here, the communication quality may be RSRP, RSRQ, RSSI, SINR, SNR, SIR, CSI, CQI, PMI, or RI.

[0293] RSRP (Reference Signal Received Power) indicates the power level of a reference signal received from a specific communication point. This value shows how strongly the receiver is receiving the reference signal. RSRP is used, for example, to evaluate the quality of communication.

[0294] RSRQ (Reference Signal Received Quality) is an index that indicates the level of noise relative to RSRP. In other words, RSRQ represents the ratio of signal strength to noise level. RSRQ is used, for example, to evaluate signal quality.

[0295] RSSI (Received Signal Strength Indicator) is a value that indicates the strength of a received signal. RSSI is used, for example, to measure the strength of a wireless communication signal. However, unlike other indicators, RSSI does not contain information about the quality of a particular signal.

[0296] SINR (Signal-to-Interference-plus-Noise Ratio) indicates the ratio of signal to interference / noise.

[0297] SNR (Signal-to-Noise Ratio) indicates the ratio of signal to noise.

[0298] SIR (Signal-to-Interference Ratio) indicates the ratio of signal to interference. SIR is used to evaluate the quality of communications.

[0299] Channel State Information (CSI) is information that indicates the state of a radio propagation path. CSI is used to understand the characteristics or quality of a communication path.

[0300] The Channel Quality Indicator (CQI) is an indicator of the quality of a radio propagation path. The CQI corresponds to the frequency utilization efficiency according to a given modulation scheme and the number of MIMO layers.

[0301] The PMI (Precoding Matrix Indicator) indicates a matrix for effectively transmitting signals between transmitting antennas in MIMO (Multiple-Input Multiple-Output) communication.

[0302] RI (Rank Indicator) indicates the number of MIMO layers in MIMO communication (e.g., rank number, number of transmitting antennas, or available spatial multiplexing).

[0303] (F3) A second signal for measuring the characteristics between communication points may be a signal for measuring (detecting, recognizing, measuring, or reporting) the relative characteristics (quality, or features) between communication points. The communication quality of each communication point may be measured using the second signal. The relative characteristics between communication points may be used to report in initial access control.

[0304] Furthermore, the relative characteristics between communication points may include differences in propagation characteristics between communication points. Differences in propagation characteristics between communication points may also be information indicating differences in propagation characteristics between communication points, or changes in propagation characteristics between communication points. Differences in propagation characteristics between communication points may include, for example, at least one of the following: Differences in received power (e.g., RSRP, path loss, or SNR) between communication points Differences in delay time (e.g., arrival time, or delay dispersion) between communication points Differences in Doppler frequency between communication points Differences in phase between communication points Differences in the above-mentioned communication quality between communication points

[0305] In determining the differences in propagation characteristics between communication points, the reference communication point may be predetermined or defined, or it may be determined by a predetermined criterion. For example, the reference communication point may be any of the following: • The communication point with the smallest or largest value associated with the communication point (e.g., communication point ID (index)) • The communication point with the largest or smallest received power • The communication point with the fastest or slowest arrival time • The communication point with the best or worst communication quality for the communication point

[0306] Furthermore, the reference communication point may be determined based on a second signal transmitted by the communication point (for example, the transmission resource for the second signal, or an ID indicating the second signal). Alternatively, the reference communication point may be set by the first broadcast information or the second broadcast information.

[0307] (F4) The second synchronization signal transmitted from the communication point may be a synchronization signal having the same function, purpose, and configuration as, for example, the PSS and / or SSS in 5G. Alternatively, the second signal may be a synchronization signal having the same function, purpose, and configuration as, for example, the PSS and / or SSS in 5G.

[0308] <Second piece of information> Next, I will explain the second piece of information.

[0309] The second broadcast information is information broadcast from the communication point and is different from the first broadcast information (or channel). For example, the first broadcast information may be an MIB and the second broadcast information may be an SIB. Alternatively, the first broadcast information may be SIB1 and the second broadcast information may be an SIB other than SIB1. Alternatively, the first broadcast information may be an MIB and SIB1 and the second broadcast information may be an SIB other than SIB1. Note that the second broadcast information does not have to be information transmitted in one transmission unit, one resource, or one channel. The first broadcast information may be transmitted in multiple transmission units, multiple resources, or multiple channels.

[0310] The second broadcast information is, for example, information (or channel) with the same function, purpose, and configuration as a PBCH in 5G. Alternatively, the second broadcast information is, for example, information (or channel) with the same function, purpose, and configuration as a PBCH in 5G. Alternatively, the second broadcast information is information (or channel) with the same function, purpose, and configuration as MIB and / or SIB in 5G (NR) and 4G (LTE). Alternatively, the second broadcast information is, for example, information (or channel) with the same function, purpose, and configuration as MIB and / or SIB in 5G (NR) and 4G (LTE). Of course, the second broadcast information is not limited to this information (or channel).

[0311] <3-3. Supplementary Information> In this embodiment, the conventional methods are based on the 3GPP technical specifications TS 38.331 and TS 36.331. TS 38.331 and TS 36.331 define specifications for SI (System Information). TS 38.331 and TS 36.331 state that OSI (Other SIBs) are indicated by SIB1 and transmitted (on demand). Here, OSI refers to SIB2 and subsequent SIBs. Furthermore, TS 38.331 and TS 36.331 stipulate that SIB1 contains information such as SIB mapping information, SI message, periodicity, and SI-window size, and that after an RRC connection is established, changes to the SIB configuration are notified via the RRC.

[0312] <<4. Operation of the Communication System>> Based on the above, the operation of communication system 1 will be explained in detail.

[0313] <4-1. Explanation of Terms> First, we will explain some terms that are prerequisites for describing the operation.

[0314] (First Initial Access Signal) The first initial access signal refers to an initial access signal used in conventional standards (e.g., NR and / or LTE). Specifically, the first initial access signal is a signal (synchronization signal and / or broadcast information) used in conventional standards to inform terminal devices of information regarding initial access to the cellular network. For example, the first initial access signal may be an initial access signal having a signal configuration defined in the 5G (NR) communication standard (e.g., SSB and / or SIB1), or an initial access signal having a signal configuration defined in the communication standard of a generation prior to 5G (e.g., 4G (LTE)) (e.g., PSS / SSS and / or SIB1). The first initial access signal may include a signal (CORESET#0) that notifies resource information of the first broadcast information.

[0315] In the following explanation, the SSB used for synchronization and / or notification of broadcast information in conventional systems (5G and systems prior to 5G) may be referred to as the first SSB. Similarly, the PSS / SSS of conventional 4G (LTE) may also be referred to as the first SSB. Furthermore, in the following explanation, the SIB1 used for notification of important broadcast information in conventional systems may be referred to as the first SIB1.

[0316] (Second Initial Access Signal) The second initial access signal refers to an initial access signal that is lighter than the conventional initial access signal (first initial access signal). Here, a lighter signal refers to a signal that reduces the amount of information transmitted from the conventional signal and reduces the resources required for transmission. The second initial access signal is an initial access signal configured to require fewer resources to transmit the information constituting the initial access signal than the first initial access signal. For example, the second initial access signal does not include at least one piece of information constituting the first initial access signal, and requires fewer resources to transmit than the first initial access signal. The second initial access signal, like the first initial access signal, is a signal (synchronization signal and / or broadcast information) used to inform the terminal device 40 of information regarding initial access to the wireless network. Here, the wireless network is not limited to a cellular network, but may be a cell-free network.

[0317] The second initial access signal may be a lightweight SSB and / or a lightweight SIB1. In the following description, the lightweight SSB may be referred to as the second SSB, and the lightweight SIB1 may be referred to as the second SIB1. The second initial access signal may include a lightweight CORESET#0. In the following description, this lightweight CORESET#0 may be referred to as the second CORESET#0.

[0318] The second initial access signal is not limited to a signal that is a lightweight version of the conventional signal. For example, the second initial access signal may be an initial access signal with a new signal configuration that is lighter than the first initial access signal.

[0319] Furthermore, a third initial access signal, a fourth initial access signal, ... and N initial access signals can be defined by differences in patterns (e.g., information quantity and / or signal configuration). Here, the pattern may be one that uses only one of the SSB or SIB1, such as using the second SSB or SIB1. However, in this embodiment, initial access signals having a pattern different from the first initial access signal may be referred to as the second initial access signal.

[0320] The second initial access signal will be described in detail later.

[0321] (First Uplink Signal) The first uplink signal is the uplink signal that the terminal device 40 initially transmits to the communication point when performing wireless communication with the communication point. In the case of a cellular communication system (for example, an LTE system or an NR system), the first uplink signal is a signal that is called PRACH or Msg1, etc.

[0322] (Standalone Operation) Standalone operation refers to the operation in which one or more communication points perform initial access with one or more terminal devices 40 without requiring support or notification of information from other communication points. As described above, a communication point may be a single base station 20 or a cluster (for example, a group of multiple communication points).

[0323] (Resources) In this embodiment, resources represent, for example, Frequency, Time, Resource Element (including REG, CCE, CORESET), Resource Block, Bandwidth Part, Component Carrier, Symbol, Sub-Symbol, Slot, Mini-Slot, Subslot, Subframe, Frame, PRACH occasion, Occasion, Code, Multi-access physical resource, Multi-access signature, or Subcarrier Spacing (Numerology).

[0324] (Other) In this embodiment, wireless communication systems (cellular communication systems) of generations prior to 5G are sometimes referred to as conventional systems. Conventional systems may be NR systems (5G wireless communication systems) or LTE systems (4G wireless communication systems).

[0325] In the following explanations, while specific values ​​are sometimes given when illustrating concrete examples, you may use different values ​​than those shown in those examples.

[0326] <4-2. Overview of Operation> Next, an overview of the operation of communication system 1 will be explained.

[0327] In conventional wireless communication, latency is a critical factor, for example, to realize URLLLC. Therefore, conventional initial access signals (e.g., SSB / SIB1 used in NR systems) contain a large amount of information. As a result, the time / frequency resources required to transmit the initial access signal are substantial. In the standalone operation of the base station 20, the initial access signal needs to be transmitted repeatedly for the terminal device 40 to recognize the presence of the base station 20. Therefore, the large resource requirements of the initial access signal lead to poor power efficiency.

[0328] In the future, as the number of communication points increases in 6G systems (e.g., self-free communication systems), the above problem (power efficiency problem) is expected to become more significant. Furthermore, in order to ensure network area coverage, networks operating in environments with a small number of connected terminals (or in environments with low connection frequency) are expected to require communication methods that prioritize power efficiency over latency. However, conventional initial access signals are insufficient to address such use cases.

[0329] To solve the above problems, in this embodiment, the communication system 1 operates as follows. Figure 19 is a diagram illustrating the overview of the operation of the communication system 1. As described above, the communication system 1 of this embodiment comprises one or more communication points and one or more terminal devices 40. The overview of the operation of the communication points and the overview of the operation of the terminal devices 40 will be described below.

[0330] <4-2-1. Overview of Communication Point Operation> First, we will explain the overview of the operation of the communication point.

[0331] The communication point in this embodiment is the communication point to which the terminal device 40 attempts to connect. The communication point is capable of exchanging information with the terminal device 40 via wireless communication. As described above, the communication point may be a base station 20 or a relay station 30. The communication point may also be a cluster composed of multiple communication points. Furthermore, the communication point may be a cell that is a component of a wireless network (communication system 1). The communication point may also be referred to as a macrocell, PCell (Primary Cell), Cell A, or Standalone cell.

[0332] In this embodiment, the communication point is capable of transmitting multiple patterns of initial access signals. These multiple patterns of initial access signals may include the initial access signals described above (for example, a first initial access signal and a second initial access signal). The communication point may switch between the multiple patterns of initial access signals according to predetermined conditions. For example, the communication point may switch between the multiple patterns of initial access signals depending on the connection status of the terminal device (e.g., the number of connected terminals and / or the connection frequency) and / or the use case. For example, the communication point may transmit a first initial access signal in use cases where latency is important and a second initial access signal in use cases where power efficiency is important.

[0333] Furthermore, the communication point in this embodiment may notify the terminal device 40 of information indicating which of the multiple initial access signal patterns (for example, a first initial access signal and a second initial access signal) it is transmitting. In this case, the communication point may transmit this information by including it in, for example, CORESET#0, PSS, SSS, SSB, PBCH, or MIB. Specific notification methods will be described later.

[0334] These processes may be performed, for example, by the control unit of the communication point (e.g., a transmission control unit 231, a reception control unit 232, an allocation unit 233, a transmission control unit 331, a reception control unit 332, or an allocation unit 333).

[0335] <4-2-2. Overview of Terminal Device Operation> Next, an overview of the operation of the terminal device 40 will be explained.

[0336] In this embodiment, the terminal device 40 is initially in Idle mode or Inactive mode. The terminal device 40 detects and demodulates the initial access signal transmitted from the communication point. Then, based on the information contained in the initial access signal, the terminal device 40 transmits a first uplink signal for initial access (e.g., PRACH / Msg1). This causes the terminal device 40 to attempt to connect to the communication point.

[0337] The terminal device 40 can recognize which pattern of initial access signal the initial access signal detected by cell search or the like is, based on information from the communication point. As described above, the information indicating which pattern of initial access signal the communication point is transmitting may be included, for example, in CORESET#0, PSS, SSS, SSB, PBCH, or MIB.

[0338] The terminal device 40 can transmit a first uplink signal based on information obtained by demodulating a second initial access signal (for example, signal configuration, transmission timing information, and power control information). Here, the information obtained by demodulating the second initial access signal may include at least one of the following: information on the signal configuration of the first uplink signal, transmission timing information, and power control information. The terminal device 40 may also generate a first uplink signal based on information on the signal configuration of the first uplink signal that it possesses in advance.

[0339] The terminal device 40 may have pre-configured information (presets) for demodulating the second initial access signal. For example, the terminal device 40 may have pre-configured information (presets) of at least one of the following: time / frequency resource allocation information, resource allocation information for the reference signal for demodulation, scrambling pattern information, and MCS (Modulation and Coding Scheme) information. Furthermore, when the terminal device 40 recognizes which pattern the received initial access signal is, it may demodulate the second initial access signal using the above-mentioned pre-configured information (presets). As a result, the terminal device 40 may obtain information for transmitting the first uplink signal.

[0340] Furthermore, the terminal device 40 may have in advance information on resources available for transmitting uplink signals as resource allocation information relative to the resources for receiving the initial access signal. The terminal device 40 may also select a transmission timing from a list of candidates and transmit the first uplink signal.

[0341] These processes may be performed, for example, by the control unit 43 of the terminal device 40 (for example, the transmission control unit 431 or the reception control unit 432).

[0342] <4-3. Second Initial Access Signal> Next, we will explain the second initial access signal.

[0343] The signals used in this embodiment may be generated by means similar to the signal generation processes used in wireless transmissions such as downlink transmission, uplink transmission, and sidelink transmission. Furthermore, the signals / information used in this embodiment may be generated by means similar to the signal generation processes used in IAB (Integrated Airborne Transmission).

[0344] The signal configuration of the second initial access signal is described below. As mentioned above, the third initial access signal, the fourth initial access signal, ... and the Nth initial access signal may be defined by differences in patterns (e.g., amount of information, and / or signal configuration). In this case, the description of the second initial access signal above or below can be replaced with the third initial access signal, the fourth initial access signal, ... or the Nth initial access signal as appropriate.

[0345] The signal configuration of the second initial access signal may be a signal configuration that does not depend on the signal configuration of the first initial access signal (hereinafter also referred to as the new signal configuration), or it may be a signal configuration that depends on the signal configuration of the first initial access signal (hereinafter also referred to as the signal configuration corresponding to the conventional signal configuration).

[0346] <4-3-1. Second Initial Access Signal with Novel Signal Configuration> The second initial access signal may be a lightweight initial access signal with a novel signal configuration.

[0347] Figure 20 is a diagram illustrating the signal configuration of a second initial access signal. Specifically, Figure 20 is a diagram illustrating an example of a signal configuration of a second initial access signal with a novel signal configuration. In the example in Figure 20, the signal configuration of a synchronization signal (the synchronization signal block shown in Figure 20) is shown as the second initial access signal. For comparison, in addition to the signal configuration of the synchronization signal of this embodiment, Figure 20 also shows the signal configurations of conventional synchronization signals (for example, LTE synchronization signals and NR synchronization signals). In the following description, conventional synchronization signals (synchronization signals with signal configurations defined in 5G or earlier generation communication standards (first signals)) may be referred to as the first synchronization signal.

[0348] The second initial access signal comprises at least one of a synchronization signal block (hereinafter also referred to as the first synchronization signal block) and a broadcast information block (hereinafter also referred to as the first broadcast information block). The first synchronization signal block is a novel synchronization signal having a signal configuration different from that of a conventional synchronization signal (the first synchronization signal). The first broadcast information block is novel broadcast information having a signal configuration different from that of conventional broadcast information.

[0349] It should be noted that in this embodiment, the first synchronization signal block is distinct from the first synchronization signal. The first synchronization signal block is a lightweight synchronization signal, while the first synchronization signal is a conventional synchronization signal.

[0350] Furthermore, in this embodiment, it should be noted that the first notification information block is distinct from the first notification information. The first notification information block is lightweight notification information. On the other hand, the first notification information may be conventional notification information (for example, the first SIB1) or lightweight notification information (for example, the first notification information block or the second SIB1).

[0351] The communication point may, for example, transmit a signal mapping a first synchronization signal block and a first broadcast information block to resources as a second initial access signal. Alternatively, the communication point may transmit a signal mapping a first synchronization signal block and conventional broadcast information (e.g., first SIB1) to resources as a second initial access signal. Alternatively, the communication point may transmit a signal mapping a conventional synchronization signal (first synchronization signal) and a first broadcast information block (e.g., second SIB1) to resources as a second initial access signal. In addition, the communication point may transmit a signal mapping a conventional signal (e.g., first SSB) and a first broadcast information block (e.g., second SIB1) to resources as a second initial access signal.

[0352] The communication point may map the synchronization signal and broadcast information onto the resource using either TDD (Time Division Duplex) or FDD (Frequency Division Duplex). In the following explanation, the combined result of mapping the synchronization signal and broadcast information will be referred to as the second initial access signal.

[0353] <First Synchronization Signal Block> The first synchronization signal block is a signal used by the terminal device 40 to synchronize time and frequency with the communication point. For example, the first synchronization signal block is a signal corresponding to PSS and / or SSS in a conventional system (e.g., an NR system and / or an LTE system).

[0354] As described above, it should be noted that in this embodiment, the first synchronization signal block is distinct from the first synchronization signal. The first synchronization signal block is a lightweight synchronization signal. On the other hand, the first synchronization signal is a conventional synchronization signal.

[0355] The communication point may use the first synchronization signal block to explicitly or implicitly notify the terminal device 40 of information related to the first broadcast information block (for example, information on the placement of reference signals (for example, DM-RS (Demodulation Reference Signal))).

[0356] The communication point may use the first synchronization signal block to notify the terminal device 40 of the communication point's cell ID (e.g., PCI (Physical cell ID)). In this case, the notified cell ID may be shared with the first initial access signal. The communication point may also use some of the cell IDs as unique values ​​for the cell transmitting the second initial access signal. By notifying the cell ID, the communication point may enable the terminal device 40 to recognize which pattern of initial access signal it is (e.g., whether it is the first initial access signal or the second initial access signal).

[0357] The communication point may transmit the first synchronization signal block using the same resources (hereinafter also referred to as the first resources) that were used to transmit the signals (e.g., PSS and / or SSS) that were used for synchronization in the conventional initial access signal (second initial access signal). For example, the communication point may transmit the first synchronization signal block using the resources that were used to transmit the PSS in the conventional system. Alternatively, the communication point may transmit the first synchronization signal block using the resources that were used to transmit the SSS in the conventional system. Alternatively, the communication point may transmit the first synchronization signal block using the resources that were used to transmit both the PSS and SSS in the conventional system.

[0358] The communication point may transmit the first synchronization signal block using a first resource (the same resource as before) while simultaneously using a different resource (a second resource). For example, the communication point may assign the first synchronization signal block to a resource that contains the transmission resource for the first initial access signal (e.g., PSS and / or SSS). In this case, the terminal device 40 may demodulate part or all of the first synchronization signal block in the same way as the first initial access signal. The terminal device 40 may then explicitly or implicitly recognize which pattern of initial access signal the transmitted initial access signal is from the demodulation result of the common resource.

[0359] Here, the communication point may explicitly notify which pattern of initial access signal it is using PCI (Physical Cell ID). The terminal device 40 may then explicitly recognize which pattern of initial access signal it is based on the PCI indication. Note that the method for making the initial access signal pattern explicitly recognizable is not limited to the above, and may simply involve allocating bits for notification. Furthermore, the method for making the initial access signal pattern recognizable may be an implicit recognition method. For example, the terminal device may estimate (implicitly recognize) which pattern of initial access signal it is based on differences in signal configuration such as a scrambling pattern.

[0360] To reduce the amount of information notified to the terminal device 40, the communication point may map the resources of the first synchronization signal block to fixed resources (for example, fixed time and / or fixed frequency).

[0361] <First Notification Information Block> The first notification information block is a signal for notifying the terminal device 40 of the information necessary to transmit the first uplink signal to the communication point. The first notification information block may be information that has been lightened from the conventional first notification information (the first notification information transmitted in the conventional system). The first notification information block may be limited to the minimum information necessary for the terminal device 40 to transmit the first uplink signal to the communication point.

[0362] The first broadcast information block is, for example, a signal corresponding to PBCH and / or SIB1 in an NR system. Alternatively, the first broadcast information block is, for example, a signal corresponding to MIB and / or SIB1 in an LTE system.

[0363] As described above, it should be noted that in this embodiment, the first notification information block is distinct from the first notification information. The first notification information block is lightweight notification information. On the other hand, the first notification information may be conventional notification information (for example, the first SIB1) or lightweight notification information (for example, the first notification information block or the second SIB1).

[0364] The communication point may use the first broadcast information block to explicitly or implicitly notify the terminal device 40 of information regarding the first uplink signal.

[0365] Here, the first broadcast information block may include resource information (e.g., transmission occasion) regarding the time and / or frequency at which the first uplink signal can be transmitted, as information regarding the first uplink signal. The terminal device 40 may transmit the first uplink signal based on this resource information.

[0366] Furthermore, the first broadcast information block may include information about the signal configuration of the first uplink signal as information about the first uplink signal. In this case, the communication point may notify the signal configuration information of the first uplink signal itself (direct information), or it may notify information that makes the signal configuration identifiable (indirect information). For example, suppose that a plurality of candidate signal configurations are predefined in the terminal device 40. In this case, the communication point may notify the terminal device 40 of identification information of one or more of the plurality of candidates as information about signal configurations that can be used (indirect information). The terminal device 40 may generate the first uplink signal based on this signal configuration information.

[0367] Furthermore, the first broadcast information block may include information necessary for power control for transmitting the first uplink signal, as information related to the first uplink signal. Here, the first broadcast information block may include, for example, the transmission power information of the first synchronization signal block as information necessary for power control. Also, the first broadcast information block may include, for example, information indicating the directivity of the transmission of the first synchronization signal block (e.g., beam ID and / or true value of transmission angle) as information necessary for power control.

[0368] The information included in the first notification information block is not limited to the above. For example, the first notification information block may include information that was notified in the NR system via PBCH and / or SIB1, or information that was notified in the LTE system via MIB and / or SIB1.

[0369] Furthermore, depending on the amount of information contained in the first broadcast information block, multiple patterns of the first broadcast information block may be provided. The communication point may then switch or use different patterns according to predetermined conditions (for example, the communication use case).

[0370] The communication point may map the first broadcast information block to a resource that is fixed relative to the first synchronization signal block. In this case, the communication point may omit sending a signal that notifies the resource information of the first broadcast information (for example, CORESET#0 in an NR system).

[0371] For example, a communication point may omit information that was previously included in the PBCH and / or MIB (e.g., at least one of frequency information (e.g., bandwidth information), SFN (System Frame Number), cell barring, and SIB1 configuration). Also, for example, a communication point may omit information that was previously included in the SIB1 (e.g., at least one of PLMN, cell selection information (or cellSelectionInfo), cell barring, and information on the availability of other SIBs).

[0372] The signal configuration of the first broadcast information block is assumed to include information that enables the transmission of at least the first uplink signal. When mapping with a synchronization signal using FDD, the communication point can transmit the first broadcast information block using 1 FDM symbol (or 1 Subcarrier index) to 40 FDM symbols (or 40 Subcarrier index). When mapping with TDD, the communication point can also transmit the first broadcast information block using 1 OFDM symbol to 2 OFDM symbols. Therefore, the communication point can transmit the first broadcast information block as a periodic signal with more resource-efficient transmission than broadcast information in conventional systems (NR systems and LTE systems).

[0373] <Other> The terminal device 40 may implicitly recognize whether it can connect to the communication point (or cell barring) from information notified by the first synchronization signal block (for example, an indication of which pattern of initial access signal is being transmitted).

[0374] <4-3-2. Second initial access signal with a signal configuration corresponding to the conventional signal configuration> The second initial access signal may be a lightweight initial access signal with a signal configuration corresponding to the conventional signal configuration.

[0375] Figures 21 to 23 are diagrams illustrating the signal configuration of the second initial access signal. Specifically, Figures 21 to 23 are diagrams illustrating examples of the signal configuration of the second initial access signal having a signal configuration corresponding to the conventional signal configuration.

[0376] Figure 21 shows an example configuration of a lightweight SSB (second SSB) as a second initial access signal. For comparison, Figure 21 also shows the signal configuration of a conventional SSB (first SSB (NR SSB in the example of Figure 21)) in addition to the signal configuration of the SSB (second SSB) of this embodiment.

[0377] Figure 22 shows an example configuration of a second initial access signal, which is a lighter version of the SSB (second SSB) shown in Figure 21. For comparison, Figure 22 also shows the signal configuration of a conventional SSB (first SSB (NR SSB in the example in Figure 22)) in addition to the signal configuration of the SSB (second SSB) of this embodiment.

[0378] Figure 23 shows an example configuration of a lightweight synchronization signal (the second synchronization signal (the lightweight LTE synchronization signal in the example in Figure 23)) as the second initial access signal. For comparison, Figure 23 also shows the signal configuration of a conventional synchronization signal (the first synchronization signal (the LTE synchronization signal in the example in Figure 23)) in addition to the signal configuration of the synchronization signal (the second synchronization signal) of this embodiment.

[0379] The second initial access signal may be a signal that notifies resource information of the first broadcast information (e.g., CORESET#0), the first signal and the first broadcast information (e.g., SSB), or the first broadcast information (e.g., SIB1). Of course, the second initial access signal is not limited to these, and may be, for example, a synchronization signal (the first signal).

[0380] The second initial access signal may include at least one of these signals. For example, the second initial access signal may include, in addition to the first signal and the first broadcast information (e.g., SSB), a signal that notifies resource information of the first broadcast information (e.g., CORESET#0). Alternatively, the second initial access signal may include, in addition to the first broadcast information (e.g., SIB1), a signal that notifies resource information of the first broadcast information (e.g., CORESET#0). Of course, the second initial access signal is not limited to these, and may consist, for example, of the first signal (e.g., PSS and / or SSS) and the first broadcast information (e.g., SSB).

[0381] If the second initial access signal includes multiple signals, any of the signals may be a lightweighted signal.

[0382] For example, suppose the second initial access signal includes, in addition to the first signal and the first broadcast information (e.g., SSB), a signal that notifies resource information for the first broadcast information (e.g., CORESET#0). In this case, the first signal and the first broadcast information may be lightweight signals (e.g., the second SSB), and the signal that notifies resource information for the first broadcast information may be a conventional signal (e.g., the first CORESET#0). Conversely, the first signal and the first broadcast information may be conventional signals (e.g., the first SSB), and the signal that notifies resource information for the first broadcast information may be a lightweight signal (e.g., the second CORESET#0). Of course, the first signal and the first broadcast information may be lightweight signals (e.g., the second SSB), and the signal that notifies resource information for the first broadcast information may also be a lightweight signal (e.g., the second CORESET#0).

[0383] Furthermore, for example, suppose the second initial access signal includes, in addition to the first broadcast information (e.g., SIB1), a signal that notifies resource information for the first broadcast information (e.g., CORESET#0). In this case, the first broadcast information may be a lightweight signal (e.g., the second SIB1), and the signal that notifies resource information for the first broadcast information may be a conventional signal (e.g., the first CORESET#0). Conversely, the first broadcast information may be a conventional signal (e.g., the first SIB1), and the signal that notifies resource information for the first broadcast information may be a lightweight signal (e.g., the second CORESET#0). Of course, the first broadcast information may be a lightweight signal of a conventional signal (e.g., the second SIB1), and the signal that notifies resource information for the first broadcast information may also be a lightweight signal (e.g., the second CORESET#0).

[0384] Furthermore, for example, suppose the second initial access signal includes a first signal (e.g., PSS and / or SSS) in addition to the first broadcast information (e.g., SIB1). In this case, the first broadcast information may be a lightweight signal (e.g., the second SIB1), and the first signal may be a conventional signal (e.g., the first synchronization signal). Conversely, the first broadcast information may be a conventional signal (e.g., the first SIB1), and the first signal may be a lightweight signal (e.g., the second synchronization signal). Of course, the first broadcast information may be a lightweight conventional signal (e.g., the second SIB1), and the first signal may also be a lightweight signal (e.g., the second synchronization signal).

[0385] The following explains each of these signals.

[0386] <Signal for notifying resource information of the first broadcast information> The signal for notifying resource information of the first broadcast information is, for example, a signal corresponding to CORESET #0 of the NR system. As described above, the signal for notifying resource information of the first broadcast information may be a conventional signal (for example, the first CORESET #0) or a lightweight signal (for example, the second CORESET #0). The communication point may generate this signal (for example, the second CORESET #0) with the same resource arrangement and / or signal configuration as the first initial access signal (for example, the first CORESET #0).

[0387] Furthermore, if the first broadcast information (e.g., the first broadcast information block / first SIB1 / second SIB1) is mapped to a relatively fixed resource with respect to the synchronization signal (e.g., the first synchronization signal block / first synchronization signal / second synchronization signal), the communication point may omit the resource information of the first broadcast information (e.g., searchSpaceZero) from the second initial access signal.

[0388] Furthermore, the signal notifying resource information of the first broadcast information may include an indication for the transmission of the first broadcast information (for example, the second SIB1).

[0389] <First Signal and First Broadcast Information> The first signal and the first broadcast information are, for example, signals corresponding to the SSB of the NR system. As described above, the first signal and the first broadcast information may be conventional signals (e.g., the first SSB) or lightweight signals (e.g., the second SSB). Here, the SSB is a signal composed of, for example, a synchronization signal (e.g., PSS and / or SSS) and a PBCH. The communication point may generate this signal (e.g., the second SSB) with the same resource arrangement and / or signal configuration as the first initial access signal (e.g., the first SSB).

[0390] The communication point may dynamically assign one or more PCI values ​​from among those assignable by the synchronization signal (e.g., PSS and / or SSS) to a cell that transmits a second initial access signal. The communication point may also use this PCI to indicate the transmission of the second initial access signal to the terminal device 40. Furthermore, the communication point may dynamically assign PCI depending on the transmission status of the cell's initial access signal (e.g., which initial access signal is being transmitted).

[0391] Furthermore, the communication point may notify the terminal device 40 via PSS of an indication of which pattern of initial access signal it is transmitting. In that case, the communication point may notify the terminal device 40 of PCI statically or quasi-statically via SSS as in the conventional manner. Furthermore, the communication point may notify the terminal device 40 via SSS of an indication of which pattern of initial access signal it is transmitting. In that case, the communication point may notify the terminal device 40 of PCI statically or quasi-statically via PSS as in the conventional manner.

[0392] Furthermore, the multiple patterns of the initial access signal may include a second initial access signal with a different signal configuration. In addition, the multiple patterns of the initial access signal may include not only the second initial access signal but also the first initial access signal.

[0393] Furthermore, the communication point may transmit either the conventional PSS or the conventional SSS, or both. In this embodiment, PCI notification in the synchronization signal is not mandatory. It is sufficient that the time and frequency are synchronized in the synchronization signal. In that case, it is possible to reduce the OFDM symbol index used for the LTE synchronization signal. Also, reducing the number of symbols on the time axis is important for power efficiency. Therefore, it is acceptable for the resources occupied to increase in the frequency direction.

[0394] <First Notification Information> The first notification information is, for example, a signal corresponding to SIB1 of the NR system. As described above, the first notification information may be a conventional signal (e.g., the first SIB1) or a lightweight signal (e.g., the second SIB1). The communication point may generate this signal (e.g., the second SIB1) with the same resource arrangement and / or signal configuration as the first initial access signal (e.g., the first SIB1).

[0395] The first broadcast information in the second initial access signal includes the minimum information necessary for the terminal device 40 to transmit the first uplink signal to the communication point. This minimum information includes, for example, the transmission timing information for the first uplink signal and the information necessary for calculating the transmission power (for example, information on the transmission power / beam directivity of the second SSB or second SIB1).

[0396] Furthermore, the first broadcast information in the second initial access signal may include information on the signal configuration of the first uplink signal, except in cases where it is not necessary to notify the terminal device 40 of the signal configuration information of the first uplink signal. Here, a case where it is not necessary to notify the terminal device 40 of the signal configuration information of the first uplink signal is, for example, when the terminal device 40 uses a pre-defined signal configuration for the first uplink signal.

[0397] The communication point may transmit the second SIB1 along with the synchronization signal using FDD (Frequency Division Duplex). By minimizing the information to be notified, the initial access signal can be transmitted with fewer OFDM symbols on the time axis compared to the first SSB / first SIB1.

[0398] The communication point can reduce the size of the first broadcast information by omitting some of the information that was previously included in the first broadcast information. For example, the communication point can omit some of the information that was previously included in the conventional PBCH and / or conventional MIB (e.g., frequency information (e.g., bandwidth information)). The communication point may also omit at least one of the following: SFN (System Frame Number), cell barring, and SIB1 configuration information. The communication point may also omit some of the information that was previously included in the SIB1 (e.g., at least one of PLMN, cell selection information (or cellSelectionInfo), cell barring, and information on the availability of other SIBs). In this embodiment, it is assumed that the first broadcast information includes at least the information necessary for the terminal device 40 to transmit the first uplink signal.

[0399] When the first broadcast information is mapped with a synchronization signal using FDD, the communication point can transmit the first broadcast information using 1 FDM symbol (or 1 Subcarrier index) to 40 FDM symbols (or 40 Subcarrier index). Even when mapped using TDD, the communication point can transmit the first broadcast information using 1 OFDM symbol to 2 OFDM symbols. Therefore, the communication point can transmit the first broadcast information as a periodic signal with more resource efficiency than broadcast information in conventional systems (NR systems and LTE systems).

[0400] <4-3-3. Example of Resource Allocation> Next, an example of resource allocation for initial access signals will be explained. Figure 24 is a diagram showing an example of resource allocation for initial access signals. In the example in Figure 24, the upper diagram shows an example of conventional resource allocation (an example of resource allocation for the first initial access signal), and the lower diagram shows an example of resource allocation according to this embodiment (an example of resource allocation for the second initial access signal). Figure 25 is a diagram showing another example of resource allocation for initial access signals. Figure 25 shows only an example of resource allocation according to this embodiment (an example of resource allocation for the second initial access signal).

[0401] A communication point may allocate the transmission resource for the first uplink signal to a location temporally close to the transmission resource for the second initial access signal. Specifically, a communication point may set up frames for sending and receiving the first uplink signal within a predetermined period before and after the transmission frame of the second initial access signal. For example, in a frame configuration in TDD mode, a communication point may set up frames for sending and receiving the first uplink signal in the T frames / slots / symbols before and after the transmission frame of the second initial access signal, where T is a value of 0 or greater.

[0402] In the example in Figure 24 (lower diagram), the communication point sets up a frame for sending and receiving the first uplink signal before the transmission frame of the second initial access signal. In the example in Figure 24, T is 0, but T may be a value greater than 0. Also, in the example in Figure 25, the communication point sets up a frame for sending and receiving the first uplink signal after the transmission frame of the second initial access signal. In the example in Figure 25, T is a value greater than 0, but T may be 0.

[0403] In conventional resource allocation such as DDDSU (upper part of Figure 24), the base station 20 can only enter light sleep when the terminal device 40 is disconnected because it is allocated to uplink (UL) resources. Therefore, power efficiency is poor. However, in the resource allocation of this embodiment (for example, Figure 24 (lower part) and Figure 25), the uplink (UL) resources are combined with the initial access signal, so when the terminal device 40 is disconnected, the communication point can enter a deeper sleep (or the base station 20 can enter a state with less power consumption than conventional methods). Therefore, power efficiency is improved. Here, light sleep and deep sleep correspond to Deep Sleep, Light Sleep, and Micro Sleep used in the base station power consumption model of 3GPP TR38.864.

[0404] The terminal device 40 may also have uplink transmittable resources in advance as resource allocation information relative to the receiving resources of the second initial access signal. In this case, the transmittable resources may include resources within a predetermined period before and after the transmission frame of the second initial access signal, as shown in Figures 24 (lower diagram) and 25. The terminal device 40 selects the transmission resource (transmission timing) for the second initial access signal from among the candidates it possesses. In this case, the terminal device 40 may select resources within a predetermined period before and after the transmission frame of the second initial access signal as transmission resources. Then, the terminal device 40 may transmit the first uplink signal using the selected resources.

[0405] Furthermore, the transmission period of the second initial access signal may be longer than the conventional transmission period (the transmission period of the first initial access signal). For example, the communication point may use a transmission period longer than 160 ms (for example, at least one of 320 ms, 640 ms, and 1080 ms) as the transmission period of the second initial access signal, in addition to 20 ms, 40 ms, 80 ms, and 160 ms.

[0406] <4-4. First Uplink Signal> Next, the first uplink signal will be explained in detail.

[0407] Upon receiving the second initial access signal, the terminal device 40 transmits a first uplink signal to the communication point. The first uplink signal is, for example, a signal corresponding to Msg1 (e.g., PRACH) of the NR system. The terminal device 40 may generate the first uplink signal by means similar to those used in the past.

[0408] The terminal device 40 may generate a first uplink signal based on a predefined signal configuration. When the terminal device 40 recognizes the transmission of a second initial access signal from a communication point, it may transmit a first uplink signal to the communication point based on the predefined signal configuration and information obtained by demodulating the second initial access signal (for example, transmission timing information for the first uplink signal and information necessary for calculating the transmission power).

[0409] The communication point may notify the terminal device 40 of the information used to transmit the first uplink signal (for example, at least one of the signal configuration of the first uplink signal, transmission timing information, and information necessary for calculating the transmission power) using the second initial access signal described above.

[0410] <4-5. Transmission of the Second Initial Access Signal> Next, the transmission of the second initial access signal will be described. The following process may be performed, for example, by the control unit of the communication point (for example, the transmission control unit 231, the allocation unit 233, the transmission control unit 331, or the allocation unit 333).

[0411] <4-5-1. Transmission Conditions> First, we will explain the conditions under which the second initial access signal can be transmitted.

[0412] The communication point may transmit a second initial access signal, for example, when the conditions shown in (G1) and / or (G2) below are met.

[0413] (G1) When a communication point or a cluster of multiple communication points is operating standalone and requires repeated transmission of an initial access signal (e.g., periodic transmission). (G2) When the terminal is in Idle mode / Inactive mode.

[0414] <4-5-2. Environmental Conditions / Use Cases> Next, it will be described under what circumstances (environmental conditions / use cases) the communication point transmits which pattern of the initial access signal.

[0415] (Situation for transmitting the first initial access signal) In a situation where latency is emphasized, the communication point may transmit the first initial access signal as the initial access signal.

[0416] For example, the communication point may transmit the first initial access signal as the initial access signal when the conditions shown in the following (H1) to (H2) are satisfied. Here, the communication point may transmit the first initial access signal when it is determined that any one (or at least one) of (H1) to (H2) is satisfied. Of course, the communication point may also transmit the first initial access signal when it is determined that all of the following (H1) to (H2) are satisfied.

[0417] (H1) When the terminal device 40 performs high-speed and low-latency communication using a millimeter-wave-compatible communication point (H2) In the case of a use case that requires low latency (for example, video streaming)

[0418] (Situation for transmitting the second initial access signal) In a situation where power efficiency is emphasized, the communication point may transmit the second initial access signal as the initial access signal.

[0419] For example, the communication point may transmit the second initial access signal as the initial access signal when the conditions shown in the following (I1) to (I4) are satisfied. Here, the communication point may transmit the second initial access signal when it is determined that any one (or at least one) of (I1) to (I4) is satisfied. Of course, the communication point may also transmit the second initial access signal when it is determined that all of the following (I1) to (I4) are satisfied.

[0420] (I1) When a large number of communication points are installed For example, the communication point may transmit a second initial access signal as an initial access signal when a predetermined number or more of communication points are installed in a self-free network or the like.

[0421] (I2) When the number of connected terminals is small or zero For example, the communication point may transmit a second initial access signal as an initial access signal when the number of connected terminals is small or zero (for example, when the area where wireless communication is used is a mountainous area and / or a rural area).

[0422] (I3) When the connection frequency of the terminal is low For example, the communication point may transmit a second initial access signal as an initial access signal when the connection frequency of the terminal is low (for example, when the area where wireless communication is used is a mountainous area and / or a rural area).

[0423] (I4) In the case of a communication point that emphasizes power efficiency For example, the communication point may transmit a second initial access signal as an initial access signal when it is a communication point that emphasizes power efficiency (for example, a NES (Network Energy Saving) cell).

[0424] (Situation of switching from the first initial access signal to the second initial access signal) The communication point may switch the initial access signal from the first initial access signal to the second initial access signal when a predetermined condition is satisfied.

[0425] For example, the communication point may switch the initial access signal from the first initial access signal to the second initial access signal when the conditions shown in the following (J1) to (J2) are satisfied. Here, the communication point may switch the initial access signal from the first initial access signal to the second initial access signal when it is determined that any one (or at least one) of (J1) to (J2) is satisfied. Of course, the communication point may switch the initial access signal from the first initial access signal to the second initial access signal when it is determined that all of the following (J1) to (J2) are satisfied.

[0426] (J1) If the communication point has not communicated with any terminal device 40 for a certain period of time or longer, for example, if the communication point has not communicated with any terminal device 40 for a certain period of time (T seconds / frame / slot / symbol) or longer, the initial access signal may be switched from the first initial access signal to the second initial access signal.

[0427] (J2) If a certain period of time has elapsed since the communication point released or disconnected the last terminal device 40, for example, if the communication point released or disconnected the last terminal device 40 that was connected to the communication point by sending an RRC release message, the initial access signal may be switched from the first initial access signal to the second initial access signal after a certain period of time (T seconds / frame / slot / symbol) from that time.

[0428] (Situation where the initial access signal is switched from the second initial access signal to the first initial access signal) The communication point may switch the initial access signal from the second initial access signal to the first initial access signal when certain conditions are met.

[0429] For example, a communication point may switch the initial access signal from the second initial access signal to the first initial access signal if the following conditions (K1) to (K2) are met. Here, the communication point may switch the initial access signal from the second initial access signal to the first initial access signal if it is determined that any of (K1) to (K2) (or at least one of (K1) to (K2)) are met. Of course, the communication point may also switch the initial access signal from the second initial access signal to the first initial access signal if it is determined that all of the following conditions (K1) to (K2) are met.

[0430] (K1) If any one of the multiple terminal devices 40 enters connected mode, for example, the communication point may switch its initial access signal from the second initial access signal to the first initial access signal.

[0431] (K2) When the communication point receives the first uplink signal, for example, the communication point may switch the initial access signal from the second initial access signal to the first initial access signal.

[0432] <4-5-3. Configuration of the Second Initial Access Signal> The second initial access signal may be any combination of (L1) to (L8) below. As described above, the third initial access signal, the fourth initial access signal, ... and the Nth initial access signal may be defined by the difference in patterns. In this case, the description of the second initial access signal above or below can be replaced with the third initial access signal, the fourth initial access signal, ... or the Nth initial access signal as appropriate.

[0433] (L1) First synchronization signal block and first broadcast information block (L2) First synchronization signal block and first SIB1 (L3) First synchronization signal block and second SIB1 (L4) First SSB (or PSS / SSS in LTE) and first broadcast information block (L5) Second SSB and first broadcast information block (L6) Second SSB and second SIB1 (L7) Second SSB and first SIB1 (L8) First SSB (or PSS / SSS in LTE) and second SIB1

[0434] The communication point may indicate which pattern of initial access signal is being transmitted using signals / channels included in (L1) to (L8) above, from among the signals shown in (M1) to (M5) below. Multiple patterns of initial access signals may include patterns other than those shown in (L1) to (L8) above. Furthermore, multiple patterns of initial access signals may include not only the second initial access signal but also the first initial access signal.

[0435] Furthermore, the first broadcast information block or the second SIB1 may include, as a minimum, information for the transmission power control of the first uplink signal. Here, the information for the transmission power control of the first uplink signal may be, for example, information used by the terminal device 40 to calculate the path loss with the communication point (information on the transmission power of the first synchronization signal block or SSB (first SSB or second SSB)). Alternatively, the information for the transmission power control of the first uplink signal may be, for example, information on power ramp up when the first uplink signal is retransmitted.

[0436] As described above, the second initial access signal may be a lightweight initial access signal with a new signal configuration, or it may be a lightweight initial access signal with a signal configuration corresponding to the conventional signal configuration.

[0437] <4-5-4. Indication of Transmission of Second Initial Access Signal> The communication point may include the indication of transmission of the second initial access signal in any of the signals shown in (M1) to (M5) below (or at least one of the signals shown in (M1) to (M5)). Here, the communication point may explicitly or implicitly indicate the indication of transmission of the second initial access signal.

[0438] (M1) SSB For example, a communication point may include an indication for the transmission of a second initial access signal in the SSB. Here, the communication point may include the indication for the transmission of a second initial access signal in the PSS, in the SSS, in the PBCH, or in the MIB.

[0439] (M2) SIB1 For example, the communication point may include an indication of the transmission of the second initial access signal in SIB1 when notifying.

[0440] (M3) CORESET#0 For example, a communication point may include an indication for the transmission of a second initial access signal in CORESET#0.

[0441] (M4) searchSpaceZero For example, the communication point may include an indication to searchSpaceZero for the transmission of the second initial access signal.

[0442] (M5) First synchronization signal block For example, a communication point may include an indication for the transmission of a second initial access signal in the first synchronization signal block. Here, the communication point may include the indication for the transmission of a second initial access signal in a resource equivalent to a conventional PSS, in a resource equivalent to a conventional SSS, in a resource equivalent to a conventional PBCH / MIB, or in a PCI (Physical Cell ID).

[0443] <4-6. Communication Processing> Next, we will describe some examples of communication processing (connection processing / switching processing) in this embodiment.

[0444] In the first to third embodiments, the communication process described is the process by which the communication point and the terminal device 40 initiate a wireless connection using a second initial access signal (connection process). In the fourth embodiment, the communication process described is the process by which the communication point switches the initial access signal from a first initial access signal to a second initial access signal (switching process).

[0445] The embodiments shown below are examples of communication processing (connection processing / switching processing). The communication processing (connection processing / switching processing) in these embodiments is not limited to the processing shown in the embodiments below.

[0446] The communication processing in this embodiment may be performed, for example, by the control unit of the communication point (e.g., transmission control unit 231, reception control unit 232, allocation unit 233, transmission control unit 331, reception control unit 332, or allocation unit 333), and by the control unit 43 of the terminal device 40 (e.g., transmission control unit 431 or reception control unit 432).

[0447] <4-6-1. First Embodiment> First, the communication processing (connection processing) related to the first embodiment will be explained.

[0448] In the first embodiment, the second initial access signal is a lightweight initial access signal with a novel signal configuration. More specifically, in the first embodiment, the second initial access signal is a combination of the first synchronization signal block and the first broadcast information block.

[0449] Figure 26 is a sequence diagram showing the communication process according to the first embodiment. In the first embodiment, the communication point explicitly or implicitly notifies which pattern of initial access signal it is transmitting using the first synchronization signal block, CORESET#0, or searchSpaceZero. The communication process (connection process) according to the first embodiment will be described below with reference to the sequence diagram in Figure 26.

[0450] The communication point repeatedly (for example, periodically) transmits the second initial access signal. In the example in Figure 26, the communication point transmits the first synchronization signal block and the first broadcast information block as the second initial access signal (steps S101 and S102).

[0451] The terminal device 40 detects the first synchronization signal block by cell search. Then, the terminal device 40 demodulates the first broadcast information block (step S103). As a result, the terminal device 40 obtains the information necessary for transmitting the first uplink signal (for example, information for transmission timing power control of the first uplink signal). Here, the terminal device 40 may demodulate the first broadcast information block using the preset settings described above. Alternatively, the terminal device 40 may demodulate the first broadcast information block using the resource allocation information of the reference signal notified in the first synchronization signal block.

[0452] Subsequently, the terminal device 40 generates a first uplink signal based on the demodulated information (step S104). Then, the terminal device 40 transmits the generated first uplink signal (e.g., PRACH / Msg1) to the communication point (step S105). Note that the terminal device 40 may previously possess the uplink transmission available resources as relative resource allocation information with respect to the reception resources of the second initial access signal. And the terminal device 40 may select the transmission resources (transmission timing) of the second initial access signal from among the candidates it possesses.

[0453] The communication point identifies the terminal device 40 based on the first uplink signal (step S106). Then, the communication point responds to the first uplink signal (step S107). At the same time, the communication point transmits system information (e.g., in the NR system, information included in SIB1 and PBCH) (step S108). At this time, the communication point may include information necessary for demodulating the system information (e.g., resource information of the system information) in the response of step S107.

[0454] The terminal device 40 demodulates the system information (SI) (step S109).

[0455] <4-6-2. Second Embodiment> Next, the communication process (connection process) according to the second embodiment will be described.

[0456] In the second embodiment, the second initial access signal is a lightweight initial access signal having a signal configuration corresponding to the conventional signal configuration. More specifically, in the second embodiment, the second initial access signal is a combination of the second SSB and the second SIB1. Here, the second SIB1 may be a lightweight LTE synchronization signal (e.g., PSS). Alternatively, the second SIB1 may be included in the second SSB.

[0457] Figure 27 is a sequence diagram showing the communication process according to the second embodiment. In the second embodiment, the communication point explicitly or implicitly notifies the terminal device 40 which pattern of initial access signal it is transmitting using the second SSB, CORESET#0, or searchSpaceZero. The communication process (connection process) according to the second embodiment will be described below with reference to the sequence diagram in Figure 27.

[0458] The communication point repeatedly (for example, periodically) transmits a second initial access signal. In the example in Figure 27, the communication point transmits a second SSB (Light SSB shown in Figure 27) and a second SIB1 (Light SIB1 shown in Figure 27) as the second initial access signal (steps S201 and S202).

[0459] The terminal device 40 detects the second SSB by cell search. Here, the terminal device 40 may recognize the pattern of the second initial access signal or acquire information necessary for demodulating the resource information of the second SIB1 based on the first signal (for example, PSS and / or SSS included in the second SSB) and / or the first broadcast information (for example, PBCH included in the second SSB).

[0460] Next, the terminal device 40 demodulates the first broadcast information (step S203). This allows the terminal device 40 to obtain information necessary for transmitting the first uplink signal (for example, information for transmission timing power control of the first uplink signal). Here, the terminal device 40 may demodulate the first broadcast information using the preset settings described above. Alternatively, the terminal device 40 may demodulate the first broadcast information using resource allocation information of the reference signal notified by the first signal.

[0461] Next, the terminal device 40 generates a first uplink signal based on the demodulated information (step S204). Then, the terminal device 40 transmits the generated first uplink signal (e.g., PRACH / Msg1) to the communication point (step S205). The terminal device 40 may also have in advance uplink transmittable resources as resource allocation information relative to the receiving resources of the second initial access signal. The terminal device 40 may also select the transmission resource (transmission timing) for the second initial access signal from among the candidates it possesses.

[0462] The communication point identifies the terminal device 40 based on the first uplink signal (step S206). The communication point then responds to the first uplink signal (for example, by sending Msg2 (for example, a random access response)) (step S207). At the same time, the communication point transmits system information (SIBx shown in Figure 27) (step S208). For example, the communication point transmits information that was included in SIB1 or PBCH in the NR system as system information. At this time, the communication point may include information necessary for demodulating the system information (for example, resource information of the system information) in the response in step S207.

[0463] The terminal device 40 demodulates the system information (important SI) (step S209).

[0464] <4-6-3. Third Embodiment> Next, the communication processing (connection processing) according to the third embodiment will be described.

[0465] In the third embodiment, the second initial access signal is a combination of a conventional SSB (first SSB) and lightweight first broadcast information. Here, the first SIB1 may be an LTE synchronization signal (e.g., PSS and SSS). The lightweight first broadcast information may be the first broadcast information block or the second SIB1.

[0466] Figure 28 is a sequence diagram showing the communication process according to the third embodiment. In the third embodiment, the communication point explicitly or implicitly notifies which pattern of initial access signal it is transmitting using the first SSB, CORESET#0, or searchSpaceZero. The communication process (connection process) according to the third embodiment will be described below with reference to the sequence diagram in Figure 28.

[0467] The communication point repeatedly (for example, periodically) transmits a second initial access signal. In the example in Figure 28, the communication point transmits a first SSB (SSB shown in Figure 28) and a second SIB1 (Light SIB1 shown in Figure 28) / first broadcast information block (broadcast information block shown in Figure 28) as the second initial access signal (steps S301 and S302).

[0468] The terminal device 40 detects the first SSB by cell search. Here, the terminal device 40 may recognize the pattern of the second initial access signal or acquire information necessary for demodulating the resource information of the second SIB1 / first broadcast information block based on at least one of PSS, SSS, PBCH, CORESET#0, and searchSpaceZero.

[0469] Next, the terminal device 40 demodulates the second SIB1 / first broadcast information block (step S303). This allows the terminal device 40 to obtain the information necessary for transmitting the first uplink signal (for example, information for transmission timing power control of the first uplink signal). Here, the terminal device 40 may demodulate the second SIB1 / first broadcast information block using the preset settings described above. Alternatively, the terminal device 40 may demodulate the second SIB1 / first broadcast information block using the resource allocation information of the reference signal notified by the first signal.

[0470] Next, the terminal device 40 generates a first uplink signal based on the demodulated information (step S304). Then, the terminal device 40 transmits the generated first uplink signal (e.g., PRACH / Msg1) to the communication point (step S305). The terminal device 40 may also have uplink transmittable resources in advance as resource allocation information relative to the receiving resources of the second initial access signal. The terminal device 40 may also select the transmission resource (transmission timing) for the second initial access signal from among the candidates it possesses.

[0471] The communication point identifies the terminal device 40 based on the first uplink signal (step S306). The communication point then responds to the first uplink signal (for example, by sending Msg2 (for example, a random access response)) (step S307). At the same time, the communication point transmits system information (SIBx shown in Figure 28) (step S308). For example, the communication point transmits information that was included in SIB1 or PBCH in the NR system as system information. At this time, the communication point may include information necessary for demodulating the system information (for example, resource information of the system information) in the response in step S307.

[0472] The terminal device 40 demodulates the system information (important SI) (step S309).

[0473] <4-6-4. Fourth Embodiment> Next, the communication processing (switching processing) according to the fourth embodiment will be described.

[0474] In the fourth embodiment, the second initial access signal may be a lightweight initial access signal having a novel signal configuration, similar to the first embodiment. Alternatively, the second initial access signal may be a lightweight initial access signal having a signal configuration corresponding to a conventional signal configuration, similar to the second embodiment. Furthermore, the second initial access signal may be a combination of a conventional SSB (first SSB) and lightweight first broadcast information, similar to the third embodiment.

[0475] Figure 29 is a sequence diagram showing the communication process according to the fourth embodiment. In the fourth embodiment, the communication point is initially the terminal device 40 １ (UE shown in Figure 29) １ ) is connected to terminal device 40. １ After a certain period of time has passed since the transition to RRC inactive mode, the communication point switches the transmission of the initial access signal from the transmission of the first initial access signal to the transmission of the second initial access signal, which consumes less power. In the fourth embodiment, after the transmission of the initial access signal is switched, the terminal device 40 ２ (UE shown in Figure 29) ２ The system attempts to make an initial access to the communication point based on the second initial access signal. The communication process (switching process) according to the fourth embodiment will be described below with reference to the sequence diagram in Figure 29.

[0476] The communication point repeatedly (for example, periodically) transmits the first initial access signal (step S401). In the example in Figure 29, terminal device 40 １ (UE shown in Figure 29) １ The device enters RRC connected mode through initial access processing using the first initial access signal. The communication point is terminal device 40 １ An RRC release message is sent to (step S402). This causes the terminal device 40 １ This results in RRC inactive mode.

[0477] If no connected terminal device 40 exists within a predetermined period (T seconds / frame / slot / symbol) after the communication point sends an RRC release message, the communication point changes the operating mode to power-saving mode (step S403). When the operating mode switches to power-saving mode, the communication point switches the transmission of the initial access signal from the transmission of the first initial access signal to the transmission of the second initial access signal (step S404).

[0478] Terminal device 40 ２The terminal device 40 detects the synchronization signal (e.g., first synchronization signal block / first SSB / second SSB) included in the second initial access signal by cell search. ２ The terminal device 40 demodulates the first broadcast information (e.g., first broadcast information block / first SIB1 / second SIB1) included in the second initial access signal (step S405). ２ This acquires information necessary for transmitting the first uplink signal (for example, information for timing and power control of the first uplink signal transmission).

[0479] Next, terminal device 40 ２ The terminal device 40 generates a first uplink signal based on the demodulated information (step S406). ２ The generated first uplink signal (e.g., PRACH / Msg1) is transmitted to the communication point (step S407).

[0480] The communication point repeatedly (for example, periodically) transmits a second initial access signal (step S408). The communication point also transmits a second initial access signal to the terminal device 40 based on the first uplink signal. ２ The communication point identifies the first uplink signal (step S409). The communication point then responds to the first uplink signal (for example, by sending Msg2 (for example, a random access response)) (step S410). At the same time, the communication point transmits system information (SIBx shown in Figure 29) (step S411).

[0481] <<5. Modifications>> The above-described embodiment is merely an example, and various modifications and applications are possible.

[0482] For example, in the above embodiment, periodic transmission was exemplified as the repeated transmission of the initial access signal (first initial access signal and / or second initial access signal). However, repeated transmission is not limited to periodic transmission. Repeated transmission may be transmission with different transmission intervals.

[0483] Furthermore, in the above-described embodiment, multiple communication points within a cluster (initial cluster or new cluster) are configured to coordinately transmit information / signals to the UE (terminal device 40). In this case, the connection between the UE and the multiple communication points may be a connection using carrier aggregation technology, a connection using dual connectivity technology, or a connection using multi-connectivity technology.

[0484] Furthermore, in the above-described embodiment (for example, the fourth embodiment), the communication point switched the initial access signal to be transmitted from the first initial access signal to the second initial access signal according to predetermined conditions (for example, a use case). However, the communication point may also switch the initial access signal to be transmitted from the second initial access signal to the first initial access signal according to predetermined conditions (for example, a use case).

[0485] Furthermore, in the above-described embodiment, the first initial access signal is an initial access signal having a signal configuration defined by a 5G or earlier generation communication standard. Here, the earlier generation communication standard is not limited to 4G, but may be, for example, 3G. That is, the initial access signal is not limited to an initial access signal having a signal configuration defined by 5G or 4G, but may be, for example, an initial access signal having a signal configuration defined by 3G.

[0486] The functions of the base station 20 in this embodiment may be separated into multiple functions such as CU (Central Unit), DU (Distributed Unit), and RU (Radio Unit). In this case, the above description of base station 20 (or BS) can be replaced with CU, DU, or RU.

[0487] The control device that controls the management device 10, base station 20, relay station 30, or terminal device 40 in this embodiment may be implemented using a dedicated computer system or a general-purpose computer system.

[0488] For example, a program for performing the above-described operations is stored in a computer-readable recording medium such as an optical disc, semiconductor memory, magnetic tape, or flexible disk and distributed. Then, for example, the control device is configured by installing the program on a computer and executing the above-described process. In this case, the control device may be an external device (e.g., a personal computer) of the management device 10, base station 20, relay station 30, or terminal device 40. Alternatively, the control device may be an internal device (e.g., control unit 13, control unit 23, control unit 33, or control unit 43) of the management device 10, base station 20, relay station 30, or terminal device 40.

[0489] Alternatively, the above program may be stored on a disk drive provided by a server device on a network such as the Internet, and made available for download to a computer. Furthermore, the above functions may be realized through the cooperation of an OS (Operating System) and application software. In this case, the parts other than the OS may be stored on a medium and distributed, or the parts other than the OS may be stored on a server device and made available for download to a computer.

[0490] Furthermore, among the processes described in the above embodiments, all or part of the processes described as being performed automatically can be performed manually, or all or part of the processes described as being performed manually can be performed automatically by known methods. In addition, the processing procedures, specific names, and information including various data and parameters shown in the above document and drawings can be arbitrarily changed unless otherwise specified. For example, the various information shown in each figure is not limited to the information shown.

[0491] Furthermore, the components of each illustrated device are functionally conceptual and do not necessarily need to be physically configured as shown. In other words, the specific forms of distribution and integration of each device are not limited to those shown, and all or part of them can be functionally or physically distributed and integrated in any unit according to various loads and usage conditions.

[0492] Furthermore, the embodiments described above can be combined as appropriate in areas where the processing content does not contradict each other. Also, the order of each step shown in the sequence diagram of this embodiment can be changed as appropriate.

[0493] Furthermore, for example, this embodiment can also be implemented as any configuration that constitutes a device or system, such as a processor as a system LSI (Large Scale Integration), a module using multiple processors, a unit using multiple modules, or a set with additional functions added to a unit (i.e., a configuration of a part of a device).

[0494] The functions realized by the components described herein may be implemented in a circuit or processing circuitry programmed to realize such functions. Here, the circuit or processing circuitry may be a general-purpose processor, an application-specific processor, an integrated circuit, an ASIC (Application Specific Integrated Circuit), a CPU (a Central Processing Unit), a conventional circuit, and / or a combination thereof. The processor includes transistors and other circuits. The processor may be considered as a circuit or processing circuitry. The processor may be a programmed processor that executes a program stored in memory.

[0495] In this specification, circuits, units, and means may be hardware programmed to perform the functions described herein, or hardware that performs the functions described herein. Such hardware may be any hardware disclosed herein, or any hardware known to be programmed to perform or perform the functions described herein. If such hardware is a processor that is considered to be a type of circuit, such circuit, means, or unit may be a combination of hardware and software used to constitute such hardware and / or processor.

[0496] Furthermore, for example, this embodiment can be implemented as any configuration constituting a device or system. For instance, this embodiment can be implemented as a processor as a system LSI (Large Scale Integration), a module using multiple processors, a unit using multiple modules, or a set with additional functions added to a unit. In other words, this embodiment can also be implemented as a component of a device.

[0497] The system LSI may also be called a System on Chip (SOC). In other words, each of the devices described above or below (e.g., the management device 10, the base station 20, the relay station 30, and the terminal device 40) may be interpreted as a processor (e.g., a CPU) as a system LSI (e.g., SoC), or a module that uses or constitutes such a processor. Furthermore, or alternatively, this embodiment may be implemented by any configuration that constitutes the device or system (e.g., a modem chip (baseband chip) or an RF (Radio Frequency) section, or a combination thereof). The RF section may include at least one of an RF circuit and an RF front-end. In other words, each of the devices described above or below may be interpreted as a modem chip (baseband chip) or an RF section, or a combination thereof. Furthermore, or alternatively, each of the devices described above or below may be interpreted as a module that uses or constitutes a modem chip or an RF section.

[0498] The modem chip performs signal processing for communications within the device (including the devices described above or below). The modem chip may have at least the function of a modulator or demodulator. The RF section may have at least one of the following functions: an RF transceiver (e.g., an RF upconverter and / or an RF downconverter), a power amplifier, and a low noise amplifier. The RF transceiver converts a baseband signal to an RF frequency. The power amplifier amplifies the signal for transmission from the antenna. The low noise amplifier amplifies the weak signal received from the antenna. Furthermore, or alternatively, the RF section (in particular, the RF front end) may include at least one of the above-mentioned power amplifier, low noise amplifier, envelope tracker, filter, duplexer, multiplexer, antenna switch, and antenna tuner.

[0499] The combination of a modem chip and an RF unit may be referred to as a modem-RF system. At least a portion of the modem chip, the RF unit, or a combination thereof may be included in a system LSI (e.g., SoC). For example, processing performed by at least a portion of the modem chip, the RF unit, or a combination thereof (e.g., at least a portion of MAC layer processing / PHY layer processing) may be implemented by the system LSI. Here, MAC layer processing or PHY layer processing may be at least a portion of the processing performed by the devices in the above-described or later embodiments (e.g., management device 10, base station 20, relay station 30, and terminal device 40).

[0500] In this embodiment, a system refers to a collection of multiple components (devices, modules (parts), etc.), regardless of whether all components are located in the same enclosure. For example, multiple devices housed in separate enclosures and connected via a network, and a single device containing multiple modules in one enclosure, are both considered systems.

[0501] Furthermore, for example, this embodiment can adopt a cloud computing configuration in which a single function is shared and processed collaboratively by multiple devices via a network.

[0502] <<6. Conclusion>> According to this embodiment, the communication point (first communication device) of the communication system 1 transmits a second initial access signal to inform the terminal device 40 (second communication device) of information regarding initial access to the wireless network. The second initial access signal is configured such that the amount of resources required to transmit the information constituting the initial access signal is less than that of the first initial access signal. For example, the second initial access signal does not include at least one piece of information constituting the first initial access signal, and the amount of resources required to transmit it is less than that of the first initial access signal.

[0503] As a result, communication points do not need to transmit an excessive amount of information unnecessarily in order to achieve low latency, thus enabling high power efficiency even in environments with a small number of connected terminals (or environments with infrequent connections). Consequently, communication system 1 can achieve wireless communication with high communication performance.

[0504] The wireless network may also be a cell-free network. The second initial access signal may be a signal to inform the terminal device 40 of the information necessary for initial access to the cell-free network.

[0505] This enables the realization of a highly power-efficient, cell-free network.

[0506] Furthermore, the communication point may be capable of transmitting multiple patterns of initial access signals, including at least a first initial access signal and a second initial access signal.

[0507] This allows the communication point to transmit the optimal initial access signal according to the situation. For example, in an environment where low-latency wireless communication is required, the communication point can transmit a first initial access signal. On the other hand, in an environment where power efficiency is required, the communication point can transmit a second initial access signal.

[0508] Furthermore, the communication point may notify the terminal device 40 which of the multiple initial access signal patterns it is transmitting.

[0509] This allows the terminal device 40 to determine which pattern of initial access signal is being transmitted from the communication point. As a result, the terminal device 40 can perform efficient initial access processing.

[0510] Furthermore, the communication point may switch the initial access signal it transmits from a first initial access signal to a second initial access signal, or from a second initial access signal to a first initial access signal, according to predetermined conditions.

[0511] This allows the communication point to transmit the optimal initial access signal according to the situation. For example, when no terminal devices 40 are connected to the communication point, the communication point can switch the transmitted initial access signal from a first initial access signal to a second initial access signal. This achieves high power efficiency. On the other hand, when a new terminal device 40 is connected to the communication point, the communication point can switch the transmitted initial access signal from a second initial access signal to a first initial access signal. This enables low-latency wireless communication.

[0512] Furthermore, the second initial access signal may be a lightweight second initial access signal having a new signal configuration. For example, the second initial access signal may be an initial access signal that includes at least one of the first synchronization signal block and the first broadcast information block.

[0513] This enables high power efficiency even in environments with a small number of connected devices (or environments with infrequent connections).

[0514] Furthermore, the communication point may be capable of transmitting multiple patterns of initial access signals, including a first initial access signal and a second initial access signal. The second initial access signal may include at least a first synchronization signal block. The transmission resources of the first synchronization signal block may contain at least a portion of the transmission resources of the first synchronization signal.

[0515] This allows the terminal device 40 to detect the synchronization signal using conventional methods. Based on the detection result of the synchronization signal, the terminal device 40 can explicitly or implicitly recognize which pattern of initial access signal is being transmitted.

[0516] Furthermore, the second initial access signal may include at least the first broadcast information block. The first broadcast information block may be mapped to a resource fixed relative to the transmission resource of the first synchronization signal or the first synchronization signal block. The second initial access signal may not include information for notifying the transmission resource of the first broadcast information block (e.g., CORESET#0).

[0517] This allows the communication point to reduce the amount of information in the second initial access signal while enabling the terminal device 40 to recognize the resource location of the first broadcast information block.

[0518] Furthermore, the second initial access signal may be a lightweight initial access signal having a signal configuration corresponding to the conventional signal configuration. For example, the second initial access signal may include a second synchronization signal used by the terminal device 40 to synchronize with the communication point. Also, for example, the second initial access signal may include broadcast information that does not include at least a portion of the first broadcast information of the conventional signal configuration, but is mapped to the same transmission resource as the first broadcast information of the conventional signal configuration.

[0519] This enables high power efficiency even in environments with a small number of connected devices (or environments with infrequent connections).

[0520] Furthermore, the communication point may be capable of transmitting multiple patterns of initial access signals, including at least a first initial access signal and a second initial access signal. The second synchronization signal may also include information to notify the terminal device 40 which of the multiple initial access signal patterns is being transmitted.

[0521] This allows the terminal device 40 to determine which pattern of initial access signal is being transmitted from the communication point. As a result, the terminal device 40 can perform efficient initial access processing.

[0522] Furthermore, the communication point may allocate the transmission resource for the first uplink signal to a location that is temporally close to the transmission resource for the second initial access signal.

[0523] This allows the communication point to enter deep sleep mode when the terminal device 40 is disconnected. As a result, high power efficiency is achieved.

[0524] Furthermore, the second initial access signal may include information for controlling the transmission power of the first uplink signal.

[0525] As a result, the terminal device 40 can access the communication point even if the initial access signal transmitted from the communication point is the second initial access signal.

[0526] Although the embodiments of this disclosure have been described above, the technical scope of this disclosure is not limited to the embodiments described above, and various modifications are possible without departing from the gist of this disclosure. Furthermore, components from different embodiments and modifications may be combined as appropriate.

[0527] Furthermore, the effects described in each embodiment of this specification are merely illustrative and not limiting, and other effects may also occur.

[0528] Furthermore, this technology can also take the following configurations: (1) A communication device comprising: a transmission control unit that transmits a second initial access signal, the amount of resources required to transmit information constituting an initial access signal for informing a terminal device of information regarding initial access to a wireless network, is less than that required for transmitting a first initial access signal consisting of a synchronization signal and a broadcast signal; and a reception control unit that receives an uplink signal for initial access. (2) The communication device according to (1), wherein the wireless network is a cellular network or a cell-free network, and the first initial access signal is an initial access signal having a signal configuration defined by a 5G or earlier generation communication standard. (3) The communication device according to (1) or (2), wherein the transmission control unit is capable of transmitting a plurality of initial access signal patterns, including at least the first initial access signal and the second initial access signal. (4) The communication device according to (3), wherein the transmission control unit notifies the terminal device which of the plurality of initial access signal patterns is being transmitted. (5) The communication device according to (3) or (4), wherein the transmission control unit switches the initial access signal to be transmitted from the first initial access signal to the second initial access signal, or from the second initial access signal to the first initial access signal, according to predetermined conditions. (6) The communication device according to any one of (1) to (5), wherein the second initial access signal includes at least one of: a first synchronization signal block used to synchronize with a communication point provided by the wireless network; and a first broadcast information block used for transmitting a first uplink signal that the terminal device first transmits to the communication point in order to access the communication point provided by the wireless network, wherein the first synchronization signal block is a synchronization signal with a signal configuration different from that of a first synchronization signal with a signal configuration defined in a 5G or earlier generation communication standard; and the first broadcast information block is broadcast information with a signal configuration different from that of first broadcast information with a signal configuration defined in a 5G or earlier generation communication standard.(7) The communication device according to (6), wherein the second initial access signal includes the first synchronization signal block and the first broadcast information. (8) The communication device according to (6), wherein the second initial access signal includes the first synchronization signal and the first broadcast information block. (9) The communication device according to (6) or (7), wherein the transmission control unit is capable of transmitting a plurality of patterns of initial access signals, including the first initial access signal and the second initial access signal, the second initial access signal includes at least the first synchronization signal block, and the transmission resources of the first synchronization signal block include at least a portion of the transmission resources of the first synchronization signal. (10) The communication device according to (6) or (8), wherein the second initial access signal includes at least the first broadcast information block, the first broadcast information block is mapped to a resource fixed relative to the transmission resource of the first synchronization signal or the first synchronization signal block, and the second initial access signal does not include information for notifying the transmission resource of the first broadcast information block. (11) The communication device according to any one of (1) to (5), wherein the second initial access signal includes a synchronization signal used by the terminal device to synchronize with a communication point provided by the wireless network, the synchronization signal is a synchronization signal that does not include at least a portion of the first synchronization signal having a signal configuration defined in a 5G or earlier generation communication standard, and is mapped to the same transmission resource as the first synchronization signal. (12) The communication device according to (11), wherein the transmission control unit is capable of transmitting a plurality of initial access signal patterns, each including at least the first initial access signal and the second initial access signal, and the synchronization signal includes information for notifying a terminal device which of the plurality of initial access signal patterns is being transmitted.(13) The communication device according to any one of (1) to (5), wherein the second initial access signal includes broadcast information used for transmitting a first uplink signal that the terminal device first transmits to a communication point in order to access the communication point provided by the wireless network, wherein the broadcast information is broadcast information that does not include at least a portion of the first broadcast information having a signal configuration defined by a 5G or earlier generation communication standard, and is broadcast information that is mapped to the same transmission resource as the first broadcast information. (14) The communication device according to any one of (1) to (13), further comprising an allocation unit that allocates the transmission resource for the first uplink signal that the terminal device first transmits to the communication point in order to access the communication point provided by the wireless network to a location temporally close to the transmission resource for the second initial access signal. (15) The communication device according to any one of (1) to (14), wherein the second initial access signal includes information for transmission power control of a first uplink signal that the terminal device first transmits to a communication point in order to access the communication point provided by the wireless network. (16) A communication device comprising: a receiving control unit that receives a second initial access signal, wherein the amount of resources required to transmit the information constituting the initial access signal for informing a terminal device of information regarding initial access to the wireless network is less than that required for a first initial access signal consisting of a synchronization signal and a broadcast signal; and a transmitting control unit that transmits an uplink signal for initial access based on the information contained in the second initial access signal. (17) The communication device according to (16), further comprising a storage unit that holds information on resources available for transmitting an uplink signal as resource allocation information relative to the receiving resources of the second initial access signal. (18) A communication method comprising transmitting a second initial access signal, the amount of resources required to transmit the information constituting the initial access signal for informing a terminal device of information regarding initial access to a wireless network, is less than that required for transmitting a first initial access signal, which consists of a synchronization signal and a broadcast signal, and receiving an uplink signal for initial access.(19) A communication method comprising: receiving a second initial access signal, wherein the amount of resources required to transmit information constituting an initial access signal for informing a terminal device of initial access to a wireless network is less than that required to transmit a first initial access signal consisting of a synchronization signal and a broadcast signal; and transmitting an uplink signal for initial access based on the information contained in the second initial access signal. (20) A communication system comprising a first communication device provided by a wireless network and a second communication device connectable to the wireless network, wherein the first communication device includes a transmission control unit that transmits a second initial access signal, wherein the amount of resources required to transmit information constituting an initial access signal for informing a terminal device of initial access to the wireless network is less than that required to transmit a first initial access signal consisting of a synchronization signal and a broadcast signal; and the second communication device includes a reception control unit that receives the second initial access signal.

[0529] 1 Communication System 10 Management Device 20 Base Station 30 Relay Station 40 Terminal Device 11 Communication Unit 21, 31, 41 Wireless Communication Unit 12, 22, 32, 42 Storage Unit 13, 23, 33, 43 Control Unit 211, 311, 411 Transmission Processing Unit 212, 312, 412 Reception Processing Unit 213, 313, 413 Antenna 231, 331, 431 Transmission Control Unit 232, 332, 432 Reception Control Unit 233, 333 Allocation Unit P Communication Point

Claims

1. A communication device comprising: a transmission control unit that transmits a second initial access signal, the amount of resources required to transmit the information constituting the initial access signal for informing terminal devices of information regarding initial access to a wireless network, is less than that required for transmitting a first initial access signal, which consists of a synchronization signal and a broadcast signal; and a reception control unit that receives an uplink signal for initial access.

2. The communication device according to claim 1, wherein the wireless network is a cellular network or a cell-free network, and the first initial access signal is an initial access signal having a signal configuration defined by a 5G or earlier generation communication standard.

3. The communication device according to claim 1, wherein the transmission control unit is capable of transmitting a plurality of initial access signals, each including at least the first initial access signal and the second initial access signal.

4. The communication device according to claim 3, wherein the transmission control unit notifies the terminal device which of the plurality of initial access signal patterns is being transmitted.

5. The communication device according to claim 3, wherein the transmission control unit switches the initial access signal to be transmitted from the first initial access signal to the second initial access signal, or from the second initial access signal to the first initial access signal, according to predetermined conditions.

6. The communication device according to claim 1, wherein the second initial access signal includes at least one of: a first synchronization signal block used to synchronize with a communication point provided by the wireless network; and a first broadcast information block used for transmitting a first uplink signal that the terminal device initially transmits to the communication point in order to access the communication point provided by the wireless network, wherein the first synchronization signal block is a synchronization signal with a signal configuration different from that of a first synchronization signal with a signal configuration defined in a 5G or earlier generation communication standard, and the first broadcast information block is broadcast information with a signal configuration different from that of first broadcast information with a signal configuration defined in a 5G or earlier generation communication standard.

7. The communication device according to claim 6, wherein the second initial access signal includes the first synchronization signal block and the first broadcast information.

8. The communication device according to claim 6, wherein the second initial access signal includes the first synchronization signal and the first broadcast information block.

9. The communication device according to claim 6, wherein the transmission control unit is capable of transmitting a plurality of patterns of initial access signals, including the first initial access signal and the second initial access signal, the second initial access signal includes at least the first synchronization signal block, and the transmission resources of the first synchronization signal block include at least a portion of the transmission resources of the first synchronization signal.

10. The communication device according to claim 6, wherein the second initial access signal includes at least the first broadcast information block, the first broadcast information block is mapped to a fixed resource relative to the transmission resource of the first synchronization signal or the first synchronization signal block, and the second initial access signal does not include information for notifying the transmission resource of the first broadcast information block.

11. The communication device according to claim 1, wherein the second initial access signal includes a synchronization signal used by the terminal device to synchronize with a communication point provided by the wireless network, the synchronization signal is a synchronization signal that does not include at least a portion of the first synchronization signal having a signal configuration defined by a 5G or earlier generation communication standard, and is a synchronization signal that is mapped to the same transmission resource as the first synchronization signal.

12. The communication device according to claim 11, wherein the transmission control unit is capable of transmitting a plurality of initial access signal patterns, each including at least the first initial access signal and the second initial access signal, and the synchronization signal includes information for notifying a terminal device which of the plurality of initial access signal patterns is being transmitted.

13. The communication device according to claim 1, wherein the second initial access signal includes broadcast information used for transmitting a first uplink signal that the terminal device first transmits to a communication point in order to access a communication point provided by the wireless network, the broadcast information being broadcast information that does not include at least a portion of the first broadcast information having a signal configuration defined by a 5G or earlier generation communication standard, and is broadcast information that is mapped to the same transmission resource as the first broadcast information.

14. The communication device according to claim 1, further comprising: an allocation unit that allocates the transmission resource for a first uplink signal, which the terminal device first transmits to a communication point in order to access the communication point provided by the wireless network, to a location temporally close to the transmission resource for a second initial access signal.

15. The communication device according to claim 1, wherein the second initial access signal includes information for transmit power control of the first uplink signal that the terminal device initially transmits to the communication point in order to access the communication point provided by the wireless network.

16. A communication device comprising: a receiving control unit that receives a second initial access signal, wherein the amount of resources required to transmit information constituting an initial access signal for informing a terminal device of information regarding initial access to a wireless network is less than that required for transmitting a first initial access signal consisting of a synchronization signal and a broadcast signal; and a transmitting control unit that transmits an uplink signal for initial access based on the information contained in the second initial access signal.

17. The communication device according to claim 16, further comprising a storage unit that stores information on resources available for transmitting uplink signals as resource allocation information relative to the receiving resources of the second initial access signal.

18. A communication method comprising transmitting a second initial access signal, which is configured such that the amount of resources required to transmit the information constituting the initial access signal for informing a terminal device of information regarding initial access to a wireless network is less than that required for transmitting the first initial access signal, which is composed of a synchronization signal and a broadcast signal, and receiving an uplink signal for initial access.

19. A communication method comprising: receiving a second initial access signal, wherein the amount of resources required to transmit the information constituting the initial access signal for informing a terminal device of information regarding initial access to a wireless network is less than that required for transmitting the information constituting the initial access signal, which is composed of a synchronization signal and a broadcast signal; and transmitting an uplink signal for initial access based on the information contained in the second initial access signal.

20. A communication system comprising a first communication device provided on a wireless network and a second communication device connectable to the wireless network, wherein the first communication device includes a transmission control unit that transmits a second initial access signal configured such that the amount of resources required to transmit information constituting an initial access signal for informing a terminal device of initial access to the wireless network is less than that required for transmitting a first initial access signal composed of a synchronization signal and a broadcast signal, and the second communication device includes a reception control unit that receives the second initial access signal.

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