Discovery signal transmission in cellular systems

Abstract

Aspects relate to discovery signal transmission in a cellular system. According to one aspect, a method for wireless communication includes, in a terminal device: scanning for a discovery signal in at least one radio beam in a cell with a scanning periodicity proportional to a transmission periodicity of the discovery signal; detecting a change in the transmission periodicity of the discovery signal in the at least one radio beam; and adapting the scanning periodicity in accordance with the change in the transmission periodicity.

Description

[0001] This application is a divisional application of the invention patent application with international application number PCT / EP2015 / 073506, international application date of October 12, 2015, entered the Chinese national phase on May 9, 2018, Chinese national application number 201580084448.9, and invention title "Detection Signal Transmission in a Cellular System". Technical Field

[0002] This invention relates to wireless communication in cellular communication systems, and more particularly to the transmission of signals detected in a cell. Background Technology

[0003] The growing demand for wireless communication services is driving up business for cellular communication systems. Future cellular systems are expected to operate using higher frequencies, such as those above 3 GHz or even millimeter waves. This evolution may require advancements in transmission technologies. Summary of the Invention

[0004] According to one aspect, the subject matter of the independent claim is provided. Some embodiments are defined in the dependent claims.

[0005] One or more examples of the implementation are illustrated in more detail in the accompanying drawings and the description below. Other features will be apparent from the specification, the drawings, and the claims. Attached Figure Description

[0006] The embodiments will now be described in more detail with reference to the accompanying drawings, in which:

[0007] Figure 1 A wireless communication system to which embodiments of the present invention can be applied is shown;

[0008] Figure 2 and Figure 3 Processes for adapting to the transmission / reception of discovery signals according to some embodiments of the present invention are illustrated;

[0009] Figure 4A and 4B An embodiment for determining the periodicity of radio beam detection signal transmission in a cell is shown;

[0010] Figure 5 The present invention illustrates a process for determining the periodicity of discovery signal transmission in a network node;

[0011] Figure 6 The present invention illustrates a process for indicating the discovery of signal transmission periodicity according to an embodiment of the invention;

[0012] Figure 7An opportunity detection signal transmission according to an embodiment of the invention is illustrated;

[0013] Figure 8 The present invention illustrates a process for reallocating released resources when it is discovered that the periodicity of signal transmission is adjustable; and

[0014] Figures 9 to 11 A block diagram illustrating the structure of an apparatus according to some embodiments of the present invention is shown. Detailed Implementation

[0015] The following embodiments are exemplary. Although this specification may refer to "a," "an," or "some" embodiments in several places throughout the text, this does not necessarily mean that each reference is made to the same embodiment, or that a particular function applies only to a single embodiment. Individual features of different embodiments may also be combined to provide other embodiments.

[0016] The described embodiments can be implemented in radio systems such as at least one of the following: WiMAX for microwave access, Global System for Mobile Communications (GSM, 2G), GSM EDGE Radio Access Network (GERAN), General Packet Radio Service (GPRS), Universal Mobile Telecommunications System based on Basic Wideband Code Division Multiple Access (W-CDMA) (UMTS, 3G), High-Speed ​​Packet Access (HSPA), Long Term Evolution (LTE), LTE-Advanced and / or 5G systems. However, this embodiment is not limited to these systems.

[0017] However, these embodiments are not limited to the systems given as examples, but those skilled in the art can apply this solution to other communication systems provided with the necessary attributes. It is assumed that 5G systems use multiple-input multiple-output (MIMO) antenna technology, a greater number of base stations or nodes than LTE (the so-called small cell concept), including macro sites operating in cooperative operation with smaller stations, and may also employ various radio technologies for better coverage and enhanced data rates. 5G will likely include more than one Radio Access Technology (RAT), each optimized for certain use cases and / or spectrum. 5G mobile communications will have a wider range of use cases and related applications, including video streaming, augmented reality, different methods of data sharing, and various forms of machine-type applications, including vehicle safety, different sensors, and real-time control. 5G is expected to have multiple radio interfaces (or at least variations of the baseline design) for different scenarios (e.g., below 6 GHz, cmWave, and mmWave), and will also be compatible with existing legacy radio access technologies such as LTE. This is equally applicable to certain specific scenarios, such as machine-type communication (MTC) and unlicensed band operation. At least in the early stages, integration with LTE can be implemented as a system where LTE provides macro coverage and 5G radio interface access is aggregated from small cells to LTE. In other words, 5G plans support inter-RAT operability (such as LTE-5G) and inter-radio interface operability (such as sub-6GHz-cmWave and sub-6GHz-cmWave-mmWave). One concept considered for use in 5G networks is network slicing, where multiple independent and dedicated virtual subnetworks (network instances) can be created within the same infrastructure to run services with different requirements for latency, reliability, throughput, and mobility. It should be understood that future networks will likely utilize Network Function Virtualization (NFV), a network architecture concept that proposes virtualizing network node functions as "building blocks" or entities that can be operationally connected or linked together to provide services. Virtualized network functions (VNFs) can include one or more virtual machines running computer program code using standard or general-type servers instead of custom hardware. Cloud computing or cloud data storage can also be utilized. In radio communications, this could mean that node operations are performed at least partially on servers, hosts, or nodes operatively coupled to a remote radio head. Node operations may also be distributed across multiple servers, nodes, or hosts. It should also be understood that the distribution of labor between core network operations and base station operations may differ from, or even not exist, in LTE. Other technological advancements that may be used include software-defined networking (SDN), big data, and all-IP, which could transform how networks are built and managed.

[0018] Some embodiments of the present invention can be applied to cellular communication systems that apply beamforming to transmission within cells. Figure 1 An example of such a cellular communication system is shown. Cellular radio communication networks such as Long Term Evolution (LTE), LTE-Advanced (LTE-A), or anticipated future 5G solutions under the 3GPP program (3GPP) typically consist of at least one network element, such as network node 110 providing cell 100. For example, cell 100 can be, for example, a macro cell, micro cell, femtocell, or picocell. Network node 110 can be an evolved Node B (eNB) in LTE and LTE-A, such as a Radio Network Controller (RNC) in UMTS, a Base Station Controller (BSC) in GSM / GERAN, or any other device capable of controlling radio communications and managing radio resources within cell 100. For 5G solutions, the implementation may be similar to LTE-A, as described above. Network node 110 can be a base station or an access node. The cellular communication system can consist of a radio access network of network nodes similar to network node 110, each network node controlling one or more corresponding cells.

[0019] Network node 110 can further connect to the core network 130 of the cellular communication system via a core network interface. In one embodiment, according to LTE terminology, the core network 130 may be referred to as the Evolved Packet Core (EPC). The core network 130 may include a Mobility Management Entity (MME) and data routing elements. In the context of LTE, the MME tracks the mobility of terminal device 120 and performs the establishment of bearer services between terminal device 120 and the core network 130. In the context of LTE, the data routing elements may be referred to as a System Architecture Evolution Gateway (SAE-GW). It can be configured to perform packet routing from terminal device 120 to other parts of the cellular communication system and other systems or networks (e.g., the Internet), as well as packet routing from other parts of the cellular communication system to terminal device 120 and to other systems or networks (e.g., the Internet).

[0020] As described above, network node 110 can employ beamforming in the transmission of radio signals within cell 100. Beamforming, also known as spatial filtering in the field of wireless communication, refers to directional transmission or reception. The steering of the radio beam can be achieved through digital and / or analog signal processing techniques and the use of multiple antenna elements forming an antenna array. For example, steering can be achieved by combining elements in a phased antenna array in such a way that signals at a specific angle experience constructive interference while others experience destructive interference. Beamforming can be used in transmitters and / or receivers to achieve spatial selectivity. Spatial selectivity results in an improvement compared to omnidirectional transmission / reception, where this improvement is referred to as transmission / reception gain. The network node can employ two types of radio beams: a first type of radio beam 114 that substantially covers the entire cell 100; and a second type of radio beam 112, 113 that covers a portion of cell 100. When cell 100 is a sector-type cell among multiple sectors established by network node 110, the first type of radio beam can be referred to as a sector beam. Traditionally, cellular communication systems rely on a first type of radio beam for control plane transmission (downlink synchronization, broadcasting, common reference signals based on antenna ports, etc.) and reception (e.g., random access channel RACH). Systems such as 5G, operating at higher carrier frequencies, may require higher antenna gain, which can be achieved by using a second type of radio beam. To support cell sizes with inter-site distances of tens to hundreds of meters, common control and user plane-related signaling can utilize narrower radio beams than sector-wide radio beams. The second type of radio beam can provide a solution for this situation.

[0021] In some embodiments, network nodes may employ a first type of radio beam in the transmission of common control messages. Common control messages may be defined as messages addressing multiple or even all terminal devices located in cell 100. Network nodes may employ a second type of radio beam in the transmission of terminal device-specific control messages, such as messages addressing individual terminal devices located in the cell. In some embodiments, the first type of radio beam may be used for the transmission of terminal device-specific control messages, and / or the second type of radio beam may be used for the transmission of common control messages.

[0022] In some embodiments, beamforming is used in combination with time-division duplex (TDD) in a half-duplex manner. The transmission periodicity can be divided into downlink and uplink periods in the time domain. Network node 110 can employ beamforming for spatially filtered transmission during the downlink period and for spatially filtered reception during the uplink period. For example, the network node can employ the same spatial filtering during both the uplink and downlink periods, therefore... Figure 1 The radio beams and associated coverage areas shown can be applied to both downlink and uplink cycles.

[0023] Due to transmission power budget or architectural limitations, network node 110 may make a limited number of radio beams with the desired antenna gain available at any given time. This means that network node 110 may have to perform alternating transmission of radio beams, such that only a subset of the radio beams is active at any given time.

[0024] The terminal device can scan the channel for radio beams carrying messages from network node 110 to terminal device 120. When terminal device 120 is dynamically scheduled for downlink or uplink data, it needs to check for scheduling authorization transmitted by network node 110. Link adaptation can be applied to transmit control signaling carrying scheduling authorization to the terminal device. For example, in an LTE system, network node 110 can aggregate control channel elements (CCEs) in an open-loop manner with factors of one, two, four, or eight, based on the selected modulation and coding scheme (MCS). The required number of CCEs can depend on the channel coding rate that defines the number of transmitted symbols. Since the number of CCEs is variable and may not be signaled by network node 110, the terminal device may perform blind detection to determine the number of CCEs used for signaling. Furthermore, the control channel can have multiple formats, and the format is not necessarily known a priori to the terminal device. The number of different configurations of CCEs, or more generally, the number of messages addressed to terminal device 120, can define the search space from which the terminal device is scanning messages. The search space can define scanning configurations for terminal device 120. Different scanning configurations can define different link adaptation configurations, such as candidate MCSs, different radio beams associated with the terminal device, and / or one or more message formats. It can be seen that the number of different scanning configurations increases exponentially with the number of different variables in the search space. Therefore, narrowing the search space may be advantageous. Furthermore, adapting the search space to the current operating environment can also be advantageous.

[0025] For example, for cell discovery purposes, network node 110 may transmit one or more discovery signals in or around the radio beams of cell 100. Discovery signals may include at least one of the following signals: a synchronization signal, a reference signal for channel measurement (the reference signal may be beam-specific), a system information message, a beam identifier, and a cell identification message. All radio beams may include the same synchronization signal. One or more discovery signals transmitted in the cell may provide terminal equipment with information enabling cell detection and access to cell 100. It may also facilitate radio resource management and / or channel state information measurement by terminal equipment 120. Discovery signals may be transmitted periodically, as described below. In some cases, terminal equipment 120 may be configured to scan for discovery signals at defined scan periods. The terminal equipment may be in a mode where it searches for synchronization signals or searches for cell system information after synchronization.

[0026] Another type of discovery signal transmitted in cell 100 enables the detection of another terminal device. In such an embodiment, the discovery signal can be transmitted by the terminal device to advertise its presence to other terminal devices. This approach can be referred to as device-to-device discovery or machine-to-machine discovery, referring to discovery between two terminal devices.

[0027] Further control of the management signals can be transmitted within the cell, and some signals can be periodic. The principles of the embodiments described below can be directly applied to any periodic control or management signals or messages actually transmitted within a cell.

[0028] The number of radio beams with different beamforming configurations in a cell may exceed ten, for example, dozens or even hundreds. The number of terminal devices in cell 100 can be variable, and there are several cases where no terminal devices are located in the coverage area of ​​a radio beam. In such cases, it is advantageous to conserve resources or direct resources to the radio beam that includes the terminal devices. Figure 2 An example of such an embodiment is illustrated.

[0029] refer to Figure 2 The processing performed by the network node includes: generating (box 200) multiple radio beams in the cell, wherein the multiple radio beams include multiple beamforming configurations, and wherein at least one radio beam included in the multiple radio beams includes a discovery signal transmission; determining (box 202) whether at least one terminal device is located in the coverage area of ​​the at least one radio beam; and defining (box 204) the transmission periodicity of the discovery signal transmission based on the determination.

[0030] As described above, the transmission periodicity of the detection signal transmitted in the radio beam can be adapted to the presence of one or more terminal devices in the coverage area of ​​the radio beam. Therefore, terminal device 120 can be adapted to the scanning periodicity used in scanning the detection signal. Figure 3 This illustrates one such embodiment.

[0031] refer to Figure 3 The processing performed by the terminal device includes: scanning at least one radio beam in the cell for the discovery signal with a scanning period proportional to the transmission periodicity of the discovery signal (box 300); detecting (box 302) a change in the transmission periodicity of the discovery signal in the at least one radio beam; and adapting (box 304) the scanning periodicity according to the detected change in transmission periodicity.

[0032] The embodiments described above enable adaptation to the periodicity of discovery signal transmissions. In one embodiment, when no terminal device is detected in the coverage area of ​​the radio beam, the period can be increased, resulting in fewer discovery signal transmissions. This enables savings in transmission resources and signaling overhead. On the other hand, when one or more terminal devices are detected in the coverage area of ​​the radio beam, the period can be reduced, resulting in more frequent discovery signal transmissions. This enables lower latency in the service provided by the terminal device. This can improve the efficiency of resource utilization. Accordingly, the terminal device can adapt to the scanning periodicity and gain the advantage of efficient use of resources within the terminal device.

[0033] Now let's refer to Figure 4A and 4B This describes some embodiments for determining the presence of terminal equipment within the coverage area of ​​a radio beam. Figure 4A and 4B In one embodiment, network node 110 determines the presence of a terminal device in the coverage area of ​​a radio beam based on one or more uplink messages received from the terminal device.

[0034] Figure 4A An embodiment is shown in which network node 110 determines the presence of a terminal device within the coverage area of ​​a radio beam based on a response received from the terminal device. (Refer to...) Figure 4A In step 400, network nodes can transmit radio beams in the cell with different beamforming configurations. One or more of the radio beams may include periodically transmitted discovery signals. In block 402, terminal device 120 can scan for discovery signals at a scanning period. The scanning period may conform to the transmission periodicity of the discovery signals. As described below, the terminal device can determine the transmission periodicity based on signals received from network nodes.

[0035] As described above, the discovery signal may include a unique beam identifier for a radio beam among multiple radio beams, and allows for the identification of the radio beam. When a discovery signal carrying a beam identifier is detected in block 402, terminal device 120 may generate an uplink message including the beam identifier of the detected beam and transmit the uplink message to the network node in step 404. The same process in blocks 402 and 404 may be performed with one or more other terminal devices in cell 100. In block 406, the network node collects the uplink messages received from the terminal devices and determines, based on the received uplink messages, the radio beam in which at least one terminal device is located within its coverage area. More specifically, if the received uplink message includes a beam identifier, the network node may determine that the terminal device is located within the coverage area of ​​that radio beam.

[0036] In block 408, the network node adapts the transmission periodicity of the discovery signal in the radio beam based on block 406. For example, if no received uplink message indicates a given radio beam, the network node can set the transmission periodicity of the discovery signal in that beam to the maximum transmission periodicity associated with the longest period. On the other hand, if one or more uplink messages indicate a radio beam, the network node can choose a transmission periodicity shorter than the maximum transmission time period. In this way, the network node can adapt the transmission periodicity of the discovery signal independently for each radio beam. Since the terminal device is mobile, the network node can adapt the mobility of the terminal device between radio beams by adapting the transmission periodicity of the discovery signal accordingly. In step 400 below, the network node can now retransmit the radio beam by applying the new transmission periodicity of the discovery signal selected in block 408.

[0037] exist Figure 4A In this embodiment, the terminal device scans for downlink reference signals in block 402. Scanning may include measuring the downlink reference signals, such as the received strength of the reference signals. Accordingly, the terminal device may adapt the measurement periodicity to the transmission periodicity of the discovered signals. Measurements may refer to physical layer (layer 1), link layer (e.g., layer 2 including media access control and radio link control), and / or radio resource control layer (layer 3) measurements. In this embodiment, the uplink message transmitted in step 404 may include an uplink measurement report indicating the measurement results for the measurements. The measurement results can be used as a channel state indicator indicating the quality of the radio channel between the network node and the terminal device.

[0038] In one embodiment, the radio beam carrying the discovery signal also includes uplink transmission resources associated with the discovery signal. The uplink transmission resources may be periodic and have the same periodicity as the discovery signal in the radio beam. As a result, network nodes are able to receive uplink messages from terminal devices with the same periodicity as the transmission of the discovery signal.

[0039] Figure 4A The terminal device detects the radio beam and responds to the network node with a message indicating that the terminal device has detected the radio beam. Figure 4B The following embodiment is illustrated: a terminal device performs arbitrary uplink transmissions, and a network node determines the radio beam of the terminal device in its coverage area based on the received beamforming configuration. Figure 4B The processing can be based on applying the same beamforming configuration to both reception and transmission within the network nodes. (See reference...) Figure 4B In step 410, the terminal device performs an uplink transmission. For example, the uplink transmission may include an uplink reference signal or an uplink control message. Similarly, one or more other terminal devices located in the cell may perform uplink transmissions. In step 410, the network node may utilize multiple different receive beamforming configurations to receive uplink signals. Each receive beamforming configuration may be associated with one of the radio beams, and the receive beamforming configuration may correspond to multiple different beamforming configurations used by the network node in the transmission. In block 412, the network node 110 may determine the receive beamforming configuration that it has received at least one uplink message with.

[0040] In block 414, the network node adapts the transmission periodicity of the discovery signal in the radio beam based on block 412. For example, if no uplink message is received using a given receive beamforming configuration within a defined duration, the network node can set the transmission periodicity of the discovery signal in the radio beam corresponding to that receive beamforming configuration to the maximum transmission periodicity associated with the longest period. On the other hand, if one or more receive beamforming configurations are capable of receiving uplink messages, the network node can select a transmission periodicity shorter than the maximum transmission periodicity of the radio beam associated with those one or more receive beamforming configurations. Also in this embodiment, the network node can adapt the transmission periodicity of the discovery signal independently for each radio beam. Since the terminal device is mobile, the network node can adapt the mobility of the terminal device between radio beams by adapting the transmission periodicity of the discovery signal accordingly. In step 400 below, the network node can now retransmit the radio beam by applying the new transmission periodicity of the discovery signal selected in block 408.

[0041] In one embodiment, Figure 4A and 4B The following embodiments are applied; for example, network nodes can be based on Figure 4A The embodiments and according to Figure 4B The embodiments determine the position of the terminal device relative to the radio beam.

[0042] Another embodiment employs statistical data collected by a network node and / or another network node to determine the transmission periodicity of the discovery signal. For example, a network node may collect historical data representing the location of a terminal device within the coverage area of ​​a radio beam and use this historical data to determine the transmission periodicity of the discovery signal. The historical data may represent the temporary location of the terminal device, such as within a day, a work week, or a week. As a practical example, an office building in a cell provided by a network node may include a first area covered by a first set of radio beams and a second area covered by a second set of radio beams. During office hours, historical data may show that the terminal device is present in the coverage areas of all radio beams, and the historical data shows that the mobility of the terminal device is unpredictable. However, outside of office hours, historical data may show that no terminal device is located within the coverage area of ​​the first set of radio beams, such as in an office post or meeting room, while the random or regular presence of at least one terminal device is located within the coverage area of ​​the second set of radio beams, such as in a security post. Therefore, the network node may employ a long transmission periodicity of the discovery signal in the first set of radio beams outside of office hours and a short (even shorter) transmission periodicity of the discovery signal in the second set of radio beams. During office hours, shorter transmission periodicity can be applied to all radio beams, or the transmission periodicity can be determined based on, for example... Figure 4A The embodiment of 4B is determined.

[0043] In yet another embodiment, network nodes may employ external information about the location of terminal devices. Such external information could include information about an event at a defined location, where the event is expected to be associated with a high density of terminal devices. Examples of such events are markets or sporting events, such as the Olympics. Network nodes can then select transmission periodicity based on this external information, for example, by selecting a short (relatively short) transmission periodicity for the radio beams that detect the event's location within their coverage area. Longer periods can be applied to other radio beams within the cell, allowing resources to be concentrated on those radio beams where high capacity is expected.

[0044] In yet another embodiment, network nodes may employ a positioning system to determine the location of terminal devices. Such a positioning system may be a Global Navigation Satellite System (GNSS) such as GPS, Galileo, GLONASS, BeiDou, DORIS, or GAGAN.

[0045] Figure 5 It shows the applicable Figure 2 , Figure 4A and / or Figure 4B Examples of embodiments and embodiments of processes executed by network nodes. See also: Figure 5 The above describes blocks 200 and 202, and Figure 4A and 4B An embodiment of block 202 is described. Block 202 and subsequent blocks 500, 502, 504 can be performed for each radio beam carrying a discovery signal. Some radio beams transmitted by the network node do not necessarily carry discovery signals. In block 500, the network node determines for the radio beam being checked whether at least one terminal device is detected in the coverage area of ​​that radio beam. When it is determined that no terminal device is detected in block 500, the process can proceed to block 502, where the network node selects a long transmission period for the discovery signal transmitted in that radio beam. Additionally, as a result of the decision made in block 500, the network node can omit the transmission of at least one message in the radio beam. For example, the network node can omit the transmission of at least one of the following downlink messages in a radio beam in which there is no terminal device: a terminal device-specific control message, a terminal device-specific data message, at least one common control message common to multiple terminal devices, and at least one downlink reference signal. As a result, fewer message types are transmitted in the radio beam or multiple radio beams, thereby further reducing the signaling overhead in radio beams in which there are no terminal devices in their coverage area. Similarly, when a specific radio beam is detected to be transmitted at maximum transmission periodicity, the terminal device can determine that the radio beam does not contain information related to the terminal device, and for example, the terminal device can remove the radio beam from the list of candidate radio beams from which the terminal device searches for control messages.

[0046] On the other hand, when it is determined in block 500 that one or more terminal devices are located within the coverage area of ​​the radio beam, the process may proceed to block 504, where the network node selects a short transmission periodicity for signal detection. If no terminal device was detected within the coverage area of ​​the radio beam during a previous radio beam check, block 504 may include shortening the period and adding one or more messages for transmission within the radio beam. These one or more messages may include one or more message types described above in conjunction with block 502.

[0047] Processing can return from boxes 502 / 504 to box 200.

[0048] In the embodiment of block 502, the network node excludes all other control and data messages from the radio beam except for the discovery signal. In other words, when processing returns from block 502 to block 200, the radio beam transmitted by the network node only includes the discovery signal, which is transmitted periodically at maximum transmission. Return to Reference Figure 1 The network node can then transmit the discovery signal periodically at maximum transmission only in radio beam 112, and further transmit the discovery signal more frequently, and further transmit control messages and / or data in radio beam 113 in which the terminal device 120 is located.

[0049] In one embodiment, when a network node selects maximum transmission periodicity for the transmission of discovery signals in a radio beam, the network node can place the radio beam in a discontinuous transmission state, in which the network node transmits discovery signals only in the radio beam or only a reduced set of discovery signals. Therefore, a radio beam in which no terminal devices are present in its coverage area can be placed in a discovery-only state, where it is used only for advertising cells and the presence of the radio beam.

[0050] In one embodiment, a network node can determine the periodicity of discovery signal transmission separately for multiple different types of discovery signals transmitted in a radio beam. Different types of discovery signals may have different requirements for maximum or generally consistent transmission periodicity. For example, the transmission periodicity of a reference signal can be bounded by the channel coherence time. For instance, a radio beam with at least one terminal device in its coverage area can employ a 2-millisecond (ms) reference signal periodicity, a 10-ms synchronization signal periodicity, and a 20-ms physical broadcast channel periodicity. A radio beam without any terminal devices in its coverage area can employ an 80-ms periodicity for all discovery signals. Further, in one embodiment, the transmission of a physical broadcast channel may be included only every other discovery signal, and the discovery signal may include an indicator indicating whether the physical broadcast channel is included in the discovery signal. Therefore, the transmission periodicity of the physical broadcast channel can be an integer multiple of the transmission periodicity of the synchronization signal.

[0051] In one embodiment, the network node is configured to scale the periodicity of the discovery signal transmission based on the number of terminal devices located within the coverage area of ​​the radio beam. The network node may employ more than two periods, each associated with a different number of terminal devices detected within the coverage area. A higher number of detected terminal devices may be associated with a shorter period of discovery signal transmission.

[0052] Furthermore, in one embodiment, the discovery signal transmissions in different radio beams of the cell can be aligned so that network nodes will not transmit conflicting information, such as one radio beam indicating the absence of a physical broadcast channel while another radio beam indicates the presence of a physical broadcast channel.

[0053] Figure 6 An embodiment is illustrated that enables terminal device 120 to align the scanning and / or measurement periodicity with the transmission periodicity of the discovery signal for each radio beam. This process is equally applicable to embodiments where the terminal device performs blind detection of control messages transmitted within a defined transmission periodicity. The control messages may differ from the discovery messages. Reference Figure 6 After determining the transmission periodicity of the discovery signals for multiple radio beams, network node 110 can generate a notification message indicating the determined transmission periodicity for those radio beams carrying the discovery signals. For each radio beam carrying the discovery signal, the notification message may include information elements indicating the transmission periodicity of the discovery signal. In another embodiment, the notification message carries a bitmap that jointly indicates the transmission periodicity of the discovery signals for multiple radio beams. In these embodiments, the notification message may be transmitted in step 600 in multiple radio beams of a second type (covering only a portion of the cell) or in radio beams of a first type (covering the entire cell). In yet another embodiment, a separate notification message may be generated for each radio beam and transmitted in each radio beam. Thus, information about the transmission periodicity of the discovery signals for a radio beam is carried only by the radio beam itself, for example, in the discovery signal.

[0054] When a notification message is received in step 600, the terminal device determines the transmission periodicity of at least one discovery signal and adapts the scan periodicity to the transmission periodicity (block 602). The terminal device 120 may employ the scan periodicity during its time intervals for scanning discovery signals. If the terminal device cannot detect a discovery signal within a time interval matching the scan periodicity, the terminal device may determine that it cannot detect the radio beam and begin searching for another discovery signal.

[0055] In one embodiment, the network node periodically transmits a notification message (step 600). In another embodiment, the network node transmits a notification message when at least one transmission period changes (step 600). Yet another embodiment is a combination of these two embodiments.

[0056] The above embodiments relate to the periodic transmission of a detection signal within a radio beam, wherein the periodicity can be adjusted based on the presence of terminal devices within the coverage area of ​​the radio beam. The boundary of the maximum duration of the period can be defined by the maximum transmission period, and the maximum transmission periodicity can be defined in the system specification. Figure 7 In another embodiment shown, network nodes may be provided with the ability to transmit ad hoc discovery signals that are not necessarily subject to periodic constraints. Such transmission of ad hoc discovery signals may be referred to as opportunistic discovery signal transmission.

[0057] refer to Figure 7 , Figure 7 The diagram illustrates a detection signal transmission in four radio beams, represented by rectangles. Readers are advised that the number of beams is merely illustrative, and the total number of radio beams transmitting in a cell with different beamforming configurations may be much higher. Furthermore, the dimensions of the rectangles are for illustrative purposes, and the detection signal transmission may consume more energy than... Figure 7 The reduced time resources shown. Figure 7 As shown, it was found that the periodicity of signal transmission can be determined individually for each radio beam, and therefore different periodicities can be applied to different radio beams emitted simultaneously.

[0058] Additionally, network nodes can perform opportunistic signal transmissions by transmitting a discovery signal 700 in a radio beam, which deviates from the periodic discovery signal transmission currently applied to the radio beam. In another embodiment, the opportunistic discovery signal 700 differs from the periodic discovery signal in another way, for example, by having different content and / or a different identifier. For example, the opportunistic discovery signal may include an indicator indicating that the discovery signal is related to an opportunistic transmission. For example, this indicator may be transmitted in a field on a physical broadcast channel. It can also be implicitly indicated by specific (sub)frame timing.

[0059] In one embodiment, the network node enables opportunistic discovery signal transmission in a radio beam that currently employs a long period, such as the maximum transmission period, for periodic discovery signal transmission. Therefore, opportunistic discovery signal transmission can be disabled for at least one radio beam that employs the shortest periodicity for discovery signal transmission.

[0060] Network nodes can trigger the transmission of opportunistic discovery signals upon detecting an event indicating the potential presence of a terminal device in the coverage area of ​​a radio beam, thus accelerating cell discovery among such terminal devices. Let's consider handover as an example of an event triggering opportunistic transmission. A terminal device served by a first network node operating a first cell can report neighboring cell measurements to the first network node. The terminal device can detect a radio beam transmitted by a second network node operating a second cell. The second cell can be a neighboring cell of the first cell, or it can be a cell further away from the first cell, such as a local cell within a third cell adjacent to the first cell. Upon detecting and measuring the radio beam, the terminal device can report the measurement results and the beam identifier of the radio beam to the first network node. The first network node can determine, based on the received report, that the terminal device should hand over to the second cell. As a result, the first network node can transmit a handover message or multiple handover messages to the second network node. The handover message may include control signaling associated with the handover process, during which the terminal device is handed over from the first network node to the second network node. This message may include the beam identifier. Upon receiving a beam identifier related to handover, the second network node can detect that the terminal device is capable of detecting the radio beam associated with the received beam identifier. This detection can trigger the transmission of an opportunity discovery signal within the radio beam, thereby enabling accelerated cell discovery and providing discovery information to the terminal device.

[0061] The adjustable periodicity of the detection signal transmission releases or occupies resources whenever the periodicity changes. This feature can be utilized and used to improve the spectral efficiency of the radio beam carrying the detection signal and / or adjacent radio beams. Let's assume that the time-frequency resources allocated to the radio beam can also consume the same time-frequency resources from adjacent radio beams. This could be due to interference avoidance in terminal equipment capable of detecting both the radio beam and adjacent radio beams.

[0062] In one embodiment, a network node may associate uplink transmission resources with each discovery signal transmission. For example, the broadcast control channel included in the discovery signal may include information elements indicating the uplink transmission resources associated with the discovery signal. This enables terminal devices to quickly access the network when a discovery signal is detected. Uplink resources may be after the discovery signal transmission. Uplink resources may be random access channel resources. Periodic and / or opportunistic discovery signal transmissions may all be associated with uplink resources following the discovery signal transmission. Uplink resources may be between two consecutive discovery signal transmissions. Uplink resources may be closer to the earlier of two consecutive discovery signal transmissions.

[0063] In one embodiment, the network node reallocates resources freed up due to the increased length of the discovery signal transmission period. The reallocated resources may be time-frequency resources included in the radio beam carrying the discovery signal and / or in at least one adjacent radio beam. Figure 8 The process in this embodiment is illustrated. (Reference) Figure 8 In box 800, network nodes can determine to increase the frequency of discovery signal transmissions for radio beams. Box 800 can be implemented due to a decrease in the presence of terminal devices in the coverage area of ​​the radio beam. As the frequency increases, discovery signal transmissions are performed less frequently, and thus more resources are freed up for reallocation. In box 802, network nodes allocate resources to one or more other radio beams.

[0064] In one embodiment, the reallocated resource is a time-frequency resource, and the released time-frequency resource can be reallocated for data transmission associated with the terminal device. In step 804, the network node transmits an allocation message, allocating the reallocated time-frequency resource to the terminal device. The allocation message may be a downlink grant message indicating the time-frequency resource. In some embodiments, this temporary reallocation may require reconfiguration of parameters in the network node and / or the terminal device. For example, the terminal device may require new rate matching parameters that match the increased rate caused by the new time-frequency resource reallocation. In step 804, the network node may indicate such rate matching parameters in the allocation message. In block 806, after receiving the allocation message, the terminal device adapts to the new time-frequency resource, for example, by applying the new rate matching parameters. In step 400, the network node transmits a radio beam including the data allocated to the terminal device, as in step 804. In block 808, the terminal device extracts data from the allocated time-frequency resource with the adapted parameters.

[0065] In another embodiment, the resources are hardware resources. For example, the radio transceiver unit can be reassigned for use in another radio beam, or the radio transceiver unit can be placed in a power-saving mode to reduce power consumption. See the following reference... Figure 11 In more detail, the radio transceiver unit can be configured to manage a radio beam. When a radio beam is not transmitting / receiving, the radio transceiver unit can be reassigned to another radio beam, thereby increasing the capacity and / or communication quality of that radio beam.

[0066] Figures 9 to 11 An apparatus according to some embodiments of the present invention is provided. Figure 9 A device configured to perform the functions described above in conjunction with terminal device 120 is shown. Figure 10A means configured to perform the functions described above in conjunction with network node 110 is shown. Each means may include communication control circuitry 10, 30 such as at least one processor and at least one memory 20, 40 including computer program code (software) 22, 42, wherein the at least one memory and the computer program code (software) are configured, together with the at least one processor, to cause the means to perform any of the embodiments described above in conjunction with the respective means.

[0067] The memories 20 and 40 can be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory.

[0068] These devices may also include communication interfaces (TX / RX) 26, 46, which include hardware and / or software for establishing communication connections according to one or more communication protocols. The communication interfaces can provide the devices with communication capabilities for communication within a cellular communication system, such as between network node 110 and terminal device 120. The communication interfaces may include standard, well-known components such as amplifiers, filters, frequency converters, (de)modulators, and encoder / decoder circuitry, as well as one or more antennas. Communication interfaces 26, 46 may include radio interface components that provide the devices with radio communication capabilities within a cellular communication system.

[0069] Each memory 20, 40 may store configuration databases 24, 44. Configuration database 24 may store configurations for one or more radio beams. As described above, the configuration database 24 of the terminal device may store scanning configurations for at least one radio beam, such as scanning periodicity. The configuration database 44 of the network node may store transmission parameters for radio beams transmitted by the network node. The transmission parameters may define periodicity parameters for the discovery signal transmission of the radio beam.

[0070] exist Figure 10 In this embodiment, at least some functions of network node 110 can be shared between two physically separate devices, forming an operational entity. Therefore, the apparatus can be considered to depict an operational entity comprising one or more physically separate devices for performing at least some of the processes described above. Thus, utilizing this shared architecture, Figure 10The apparatus may include a remote control unit (RCU), such as a host computer or server computer, operably coupled (e.g., via a wireless or wired network) to a remote radio headend (RRH) located at a base station site. In one embodiment, at least some of the processes described in the network node's processing may be performed by the RCU. In one embodiment, the execution of at least some of the described processes may be shared between the RRH and the RCU. In this context, the RCU may include Figure 10 The components shown are included, and communication interface 46 can provide the RCU with a connection to the RRH. For example, the RRH may include radio frequency signal processing circuitry and an antenna.

[0071] In one embodiment, the RCU can generate a virtual network through which the RCU communicates with the RRH. Typically, virtual networking can involve the process of combining hardware and software network resources and network functions into a single software-based management entity (virtual network). Network virtualization may involve platform virtualization, often combined with resource virtualization. Network virtualization can be categorized into external virtual networking, which combines many networks or portions of networks into a server computer or host computer (i.e., the RCU). External network virtualization aims to optimize network sharing. Another type is internal virtual networking, which provides network-like functionality to software containers on a single system. Virtual networking can also be used to test terminal devices.

[0072] In one embodiment, the virtual network can provide flexible operational allocation between the RRH and RCU. In practice, any digital signal processing task can be executed in either the RRH or the RCU, and the boundary of responsibility transfer between the RRH and RCU can be selected based on the implementation.

[0073] refer to Figure 9 The device may include control circuitry 12, which executes control plane signaling with one or more network nodes (e.g., network node 110) operating in the cellular communication system. The control circuitry may also execute any higher-level signaling used in communication between the terminal device and the core network 130, such as authentication, service requests, and integrity protection. Control circuitry 12 may perform the transmission and reception of control messages in the terminal device. For example, the control circuitry may execute signaling related to steps 404, 410, 600, and 804 in terminal device 120. The control circuitry may further perform the aforementioned scanning of discovery signals, such as blocks 300 and 402. The control circuitry may further perform the aforementioned measurements of the radio beam, estimation of channel quality based on the measurements, and uplink transmission of measurement reports indicating channel quality.

[0074] The device may also include a data communication circuit 16 configured to perform the transmission and reception of payload data in resources allocated to terminal devices in cell 100.

[0075] The device may also include a scan controller 14 configured to manage the scanning of the discovery signal in the terminal device. For example, the scan controller may determine the scanning periodicity of the wireless beam based on the detected transmission periodicity of the discovery signal in the wireless beam searched by the device. For example, the scan controller may receive a message in step 600 and configure the control circuitry 12 to adopt the scanning period determined in block 602.

[0076] refer to Figure 10 The device may include control circuitry 32, which executes control plane signaling with terminal equipment, other network nodes in the radio access network of the cellular communication system, and network nodes in the core network 130. Control circuitry 32 may, for example, perform the transmission and reception of control messages in cell 100. For example, control circuitry may also execute signaling related to steps 404, 410, 600, and 804 in network node 110.

[0077] The device may also include a data communication circuit 36, which is configured to perform the transmission and reception of payload data with terminal equipment in cell 100.

[0078] The device may also include a beam configuration controller 38, which is configured to perform configuration of radio beams with different beamforming configurations. The beamforming configuration can define spatial filtering for each radio beam, and thus define the coverage area of ​​each beam. The beam configuration controller can schedule the transmission timing of each beam, such as uplink / downlink transmission timing. According to any of the above embodiments, the beam configuration controller 38 can also determine beam-specific transmission periodicity for discovery signals transmitted in the radio beams.

[0079] The device may also include a resource allocation controller 34 configured to receive the periodicity of discovery signal transmissions in a radio beam from a beam configuration controller and allocate resources of network nodes accordingly, such as time-frequency resources and / or device hardware resources.

[0080] Modules 12 to 18 of the communication control circuit 10 and modules 32 to 38 of the communication control circuit 30 can be considered as sub-circuits of the respective communication control circuits. They can be considered as operating modules implemented by the same physical circuit, or each module can be implemented by different physical circuits. In some embodiments, each module can be considered as a computer program module defined by dedicated computer program code.

[0081] Figure 11 Network node 110 or Figure 10 An embodiment of the transceiver architecture of the device. As described above, network nodes can employ beamforming in the transmission of radio beams, and beamforming can be achieved by using an antenna array 88 comprising multiple antenna elements. In some embodiments, the number of antenna elements can be more than four, more than eight, more than 12, more than 20, more than 100, or even more than 1000. A higher number of antenna elements allows for higher directivity of the radio beam. Furthermore, spectral efficiency can be considered related to the number of spatial streams that the network node can support. A larger number of spatial streams results in higher spectral efficiency. Reference Figure 11 Baseband modules 70, 72, and 74 can perform baseband signal processing, including modulation and channel coding, for each radio beam. The number of baseband modules 70 to 74 can correspond to the number of radio beams being transmitted, for example, M. Each baseband module can be connected to a corresponding antenna port 80. Block 82 performs antenna port virtualization, which can be described as a mapping 80 between antenna ports and transceiver units 84. In one implementation, each antenna port is mapped to a transceiver unit 84, for example, a one-to-one mapping. In another implementation, one antenna port can be connected to multiple transceiver units. The number of transceiver units can be K, and in one embodiment, K = M, while in another embodiment, K ≠ M.

[0082] Transceiver unit 84 may include a digital-to-analog (D / A) converter in the transmitter chain and an analog-to-digital converter in the receiver chain. Therefore, the transceiver unit can be the cutoff point for virtualization of the signal processing operations described above. For example, baseband modules, antenna ports, and antenna port virtualization may be performed by the RCU, or some of these may be implemented in the RRH. The transceiver unit may also include analog components conventionally used in radio transceivers. Such components in the transmitter chain may include frequency converters, power amplifiers, and RF filters. Such components in the receiver chain may include low-noise amplifiers, RF filters, and frequency converters.

[0083] The transceiver units of transceiver array 84 are connected to radio distribution network 86, which is configured to perform antenna virtualization in the radio frequency domain. The radio distribution network can then be connected to L antenna elements 88. The radio distribution network 86, together with antenna port virtualization 82 and / or baseband modules, can define the beamforming architecture of the transceiver structure and network nodes. Beamforming can be implemented using digital signal processing techniques, analog signal processing techniques, or a hybrid of analog and digital signal processing. In digital beamforming, each transceiver unit can be connected to one antenna element, and beamforming can be implemented through digital precoding, where each transmit / receive stream ( Figure 11In the embodiments, the M streams are assigned appropriate weights. In analog beamforming, the radio distribution network maps signals from the transceiver unit to multiple antenna elements and controls the amplification and phase of the applied signals differently, so as to achieve constructive and destructive interference of signals radiated from different antenna elements in a desired manner. In hybrid solutions, analog and digital beamforming techniques are employed; for example, part of the beamforming can be implemented in the digital domain and another part in the analog domain.

[0084] Let's now consider some embodiments of resource reallocation when increasing the discovery signal transmission period. In an embodiment employing analog beamforming, a radio transceiver unit can be deactivated for a duration during which no discovery signal (or any signal) transmission is performed in the radio beam associated with the radio transceiver unit. This enables scalable energy savings in network nodes based on the spatial distribution of terminal devices in the cell. Multiple transceiver units associated with multiple radio beams of unserved terminal devices can be deactivated to save power, ensuring that only discovery signals are transmitted with maximum transmission periodicity. In embodiments employing digital or hybrid beamforming, digital beamforming parameters can be adjusted based on the spatial distribution of terminal devices. For example, resources freed up from discovery signal transmission can be used in terminal device-specific communications with enhanced beamforming capabilities, resulting in higher quality radio beams serving that terminal device. This can be achieved by having a greater number of transceiver units for serving terminal devices when discovery signals are not being transmitted.

[0085] As used herein, the term "circuit" refers to all of the following: (a) a circuit implementation that is purely hardware, such as an implementation in analog and / or digital circuits only; and (b) a combination of circuits and software (and / or firmware), such as (where applicable): (i) a combination of processors or (ii) a processor / software portion, including a digital signal processor, software, and memory, which work together to enable a device to perform various functions; and (c) a circuit, such as a microprocessor or a portion of a microprocessor, that requires software or firmware for operation, even if the software or firmware does not have a physical presence. This definition of "circuit" applies to all uses of the term in this application. As another example, as used herein, the term "circuit" will also cover only an implementation of a processor (or processors) or a portion of a processor and its accompanying software and / or firmware. For example, if applicable to a particular element, the term "circuit" will also cover a baseband integrated circuit or application processor integrated circuit for a mobile phone, or a similar integrated circuit in a server, cellular network device, or another network device.

[0086] In one embodiment, combined Figures 2 to 8At least some of the described processes can be performed by means including corresponding components for performing at least some of the processes. Some example components for performing the processes may include at least one of the following: a detector, a processor (including dual-core and multi-core processors), a digital signal processor, a controller, a receiver, a transmitter, an encoder, a decoder, a memory, RAM, ROM, software, firmware, a display, a user interface, display circuitry, user interface circuitry, user interface software, display software, circuitry, an antenna, antenna circuitry, and a circuit system. In one embodiment, at least one processor, memory, and computer program code form a processing component or include components for performing the processes according to... Figures 2 to 8 One or more computer program code portions of any one or more operations of any embodiment or operation thereof.

[0087] The techniques and methods described herein can be implemented by various means. For example, these techniques can be implemented using hardware (one or more devices), firmware (one or more devices), software (one or more modules), or a combination thereof. For hardware implementation, the apparatus in the embodiments can be implemented as one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof. For firmware or software, the implementation can be executed by a module (e.g., process, function, etc.) of at least one chipset that performs the functions described herein. Software code can be stored in a memory cell and executed by a processor. The memory cell can be implemented within or outside the processor. In the latter case, it can be communicatively connected to the processor via various components as known in the art. Furthermore, the components of the systems described herein can be rearranged and / or supplemented by additional components to facilitate the implementation of various aspects of the description, etc., and as those skilled in the art will understand, they are not limited to the precise configurations illustrated in the given figures.

[0088] The described embodiments can also be implemented in the form of computer processing defined by a computer program or parts thereof. Figures 2 to 8Embodiments of the described methods can be performed by executing at least a portion of a computer program including corresponding instructions. The computer program may be in source code form, object code form, or some intermediate form, and may be stored on some medium, which may be any entity or device capable of carrying the program. For example, the computer program may be stored on a computer or processor-readable computer program distribution medium. For example, the computer program medium may be, for example, but not limited to, recording media, computer memory, read-only memory, electrical carrier signals, telecommunication signals, and software distribution packages. The computer program medium may be a non-transitory medium. The coding of the software used to perform the illustrated and described embodiments is entirely within the scope of those skilled in the art.

[0089] Although the invention has been described above with reference to the accompanying drawings, it is apparent that the invention is not limited thereto, but may be modified in several ways within the scope of the appended claims. Therefore, all words and expressions should be interpreted broadly, and they are intended to illustrate rather than limit the embodiments described. It will be apparent to those skilled in the art that the concepts of the invention can be implemented in various ways as technology advances. Furthermore, it will be clear to those skilled in the art that the described embodiments can, but are not required, be combined with other embodiments in various ways.

Claims

1. A method for wireless communication, comprising: In a terminal device, scanning at least one radio beam in a cell for a discovery signal with a scanning periodicity proportional to a transmission periodicity of the discovery signal; detecting a change in the transmission periodicity of the discovery signal in the at least one radio beam; and adapting the scanning periodicity in dependence on the change in the transmission periodicity.

2. The method of claim 1, the adapting comprising adapting a measurement periodicity associated with measurement of the discovery signal in dependence on the change in the transmission periodicity.

3. The method of claim 2, the adapting further comprising adapting an uplink transmission of a measurement report in dependence on the changed transmission periodicity.

4. The method of claim 1, the adapting comprising adapting blind detection of a control message from the discovery signal in dependence on the changed transmission periodicity.

5. The method of any preceding claim 1 to 4, wherein the detecting is based on reception of at least one message indicating the transmission periodicity of the discovery signal for the at least one radio beam.

6. The method of claim 5, wherein the message indicates a maximum transmission periodicity for the at least one radio beam, the method further comprising: in response to detecting a maximum transmission periodicity for the at least one radio beam, removing the at least one radio beam from a set of candidate radio beams from which the terminal device scans for a control message.

7. An apparatus for wireless communication, comprising: at least one processor, and at least one memory storing computer program code, wherein the processor, the memory, and the computer program code are configured to cause the apparatus to: scan at least one radio beam in a cell for a discovery signal with a scanning periodicity proportional to a transmission periodicity of the discovery signal; detect a change in the transmission periodicity of the discovery signal in the at least one radio beam; and adapt the scanning periodicity in dependence on the change in the transmission periodicity.

8. The apparatus of claim 7, wherein the processor, the memory, and the computer program code are configured to cause the apparatus to adapt a measurement periodicity associated with measurement of the discovery signal in dependence on the change in the transmission periodicity.

9. The apparatus of claim 8, wherein the processor, the memory, and the computer program code are configured to cause the apparatus to adapt an uplink transmission of a measurement report in dependence on the changed transmission periodicity.

10. The apparatus of claim 7, wherein the processor, the memory, and the computer program code are configured to cause the apparatus to adapt blind detection of a control message from the discovery signal in dependence on the changed transmission periodicity.

11. The apparatus of any of the preceding claims 7 to 10, wherein the processor, the memory, and the computer program code are configured to cause the apparatus to perform the detecting based on reception of at least one message indicating a transmission periodicity of the discovery signal for the at least one radio beam.

12. The apparatus of claim 11, wherein the message indicates a maximum transmission periodicity for the at least one radio beam, and wherein the processor, the memory, and the computer program code are configured to cause the apparatus to remove the at least one radio beam from a set of candidate radio beams from which a terminal device scans for control messages in response to detecting a maximum transmission periodicity for the at least one radio beam.

13. The apparatus of any of the preceding claims 7 to 10, further comprising a communications interface comprising hardware that provides the apparatus with radio communication capabilities in a cellular communications system.

14. An apparatus for communication, the apparatus comprising means for performing all the steps of the method according to any of claims 1 to 6.

15. A computer readable medium having stored thereon computer readable computer program code, wherein the computer program code, which when read by the computer configures the computer to perform the method according to any of claims 1 to 6.

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