Enhanced carrier selection

Abstract

An apparatus and method in a communication system for enhanced carrier selection is provided. The solution comprises selecting (300) a carrier for a first transmission to a second apparatus, controlling the transmission (302) with the selected carrier, receiving (304) a transmission from the second apparatus, and selecting (306) a carrier for a second transmission to the second apparatus based at least partly on the transmission from the second apparatus.

Description

Technical Field

[0001] Exemplary and non-limiting embodiments of the present invention generally relate to wireless communication systems. Embodiments of the present invention particularly relate to apparatus and methods in wireless communication networks. Background Technology

[0002] Wireless communication systems are constantly evolving. In recent years, vehicle-to-vehicle (V2V) wireless communication has been under investigation. It is estimated that the development of Intelligent Transportation Systems (ITS) will improve road safety and traffic efficiency. Vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication are crucial components of ITS. Vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication will enable communication related to various use cases, such as broadcasting situational awareness information for driver assistance, sending emergency alerts (e.g., braking and vulnerable road user detection) to improve safety, and performing cooperative operations such as lane merging or queuing.

[0003] Vehicle connectivity over cellular technologies (such as cellular systems developed by the 3rd Generation Partnership Project (3GPP)) is known as Cellular Vehicle-to-Everything (C-V2X). It is being standardized as 5G (or New Radio) communication systems develop. Direct vehicle-to-vehicle communication via radio access network (RAN) nodes without a physical link is called a sidelink. Summary of the Invention

[0004] The following is a simplified overview of the invention to provide a basic understanding of certain aspects of it. This overview is not a comprehensive summary of the invention. It is not intended to identify the principal / key elements of the invention, nor is it intended to define the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that follows.

[0005] According to one aspect of the present invention, the apparatus of claim 1 is provided.

[0006] According to one aspect of the present invention, a method of claim 10 is provided.

[0007] According to one aspect of the invention, a computer program including instructions as claimed in claim 15 is provided.

[0008] One or more examples of the implementation are set forth in more detail in the accompanying drawings and the description below. Other features will be apparent from the specification, the drawings, and the claims. Embodiments and / or examples and features (if any) described herein that are not within the scope of the independent claims are to be construed as examples useful for understanding various embodiments of the invention. Attached Figure Description

[0009] The embodiments of the present invention are described below by way of example only with reference to the accompanying drawings, in which...Figure 1 and Figure 2 An example of a simplified system architecture for a communication system is shown;

[0010] Figure 3 This is a flowchart illustrating some embodiments;

[0011] Figure 4 , Figure 5 , Figure 6 and Figure 7 These are signaling diagrams illustrating some embodiments of the present invention, and

[0012] Figure 8 An example of the device is shown. Detailed Implementation

[0013] Figure 1 Devices 100 and 102 are shown. For example, devices 100 and 102 may be user equipment or user terminals. Devices 100 and 102 are configured to be wirelessly connected to node 104 on one or more communication channels. Node 104 is further connected to core network 106. In one example, node 104 may be an access node, such as an (e / g)NodeB serving device in a cell. In one example, node 104 may be a non-3GPP access node. The physical link from a device to the (e / g)NodeB is called an uplink or reverse link, while the physical link from the (e / g)NodeB to the device is called a downlink or forward link. It should be understood that the (e / g)NodeB or its functionality can be implemented using any entity suitable for this purpose, such as a node, host, server, or access point.

[0014] A communication system typically includes one or more (e / g)NodeBs, which may also be configured to communicate with each other via wired or wireless links designed for this purpose. These links can be used for signaling purposes. An (e / g)NodeB is a computing device configured to control the radio resources of the communication system to which it is coupled. A NodeB may also be referred to as a base station, access point, or any other type of interface device, including relay stations capable of operating in a wireless environment. An (e / g)NodeB includes or is coupled to a transceiver. From the transceiver of the (e / g)NodeB, a connection is provided to an antenna element that establishes a bidirectional radio link with the device. The antenna element may include multiple antennas or antenna elements. The (e / g)NodeB is further connected to the core network 106 (CN or Next Generation Core NGC). Depending on the system, the counterpart on the CN side may be a Serving Gateway (S-GW, which routes and forwards user data packets), a Packet Data Network Gateway (P-GW) for providing connectivity from the device (UE) to an external packet data network, or a Mobility Management Entity (MME), etc.

[0015] This device (also known as a subscriber unit, user, user equipment (UE), user terminal, terminal equipment, etc.) illustrates a type of device on which resources on the air interface are allocated and distributed, and therefore any feature of the device described herein can be implemented by a corresponding device (such as a relay node). An example of such a relay node is a Layer 3 relay (self-backhaul relay) toward a base station.

[0016] The device typically refers to devices (e.g., portable or non-portable computing devices) that operate with or without a Universal Subscriber Identity Module (USIM), including, but not limited to, the following types of devices: mobile stations (mobile phones), smartphones, personal digital assistants (PDAs), cell phones, devices using wireless modems (alarm or measuring devices, etc.), laptops and / or touchscreen computers, tablets, game consoles, and multimedia devices. It should be understood that the device can also be a virtually exclusive uplink-only device, an example of which is a camera or camcorder that loads images or video clips onto a network. The device can also be a device capable of operating in an Internet of Things (IoT) network, a scenario in which objects are configured to transmit data over a network without human-to-human or human-to-computer interaction, such as for smart grids and connected vehicles. The device can also utilize the cloud. In some applications, the device may include a user portable device with radio components (such as a watch, headset, or glasses), and computation is performed in the cloud. The device (or, in some embodiments, a Layer 3 relay node) is configured to perform one or more of the user equipment functions.

[0017] The various techniques described in this paper can also be applied to cyber-physical systems (CPS) (systems that coordinate and control computational elements of physical entities). CPS can enable the implementation and utilization of a large number of interconnected information and communication technology (ICT) devices (sensors, actuators, processors, microcontrollers, etc.) embedded in physical objects in different locations. Mobile cyber-physical systems (physical systems under discussion in which inherent mobility is present) are a subcategory of cyber-physical systems. Examples of mobile physical systems include mobile robots and electronic devices transported by humans or animals.

[0018] Furthermore, although the device has been described as a single entity, it can implement different units, processors, and / or memory units (not all of which are in one). Figure 1 (as shown in the image).

[0019] 5G enables the use of multiple-input multiple-output (MIMO) antennas, more base stations or nodes than LTE (the so-called small cell concept), including macro sites that operate in cooperation with smaller base stations and employ various radio technologies, depending on service requirements, use cases, and / or available spectrum. 5G mobile communications support a wide range of use cases and related applications, including video streaming, augmented reality, different data sharing methods, and various forms of machine-type applications (such as (massive) machine-type communications (mMTC)), including vehicle safety, various sensors, and real-time control. 5G is expected to have multiple radio interfaces, such as sub-6 GHz or above 24 GHz, cmWave, and mmWave, and can also integrate with existing legacy radio access technologies (such as LTE). Integration with LTE can be implemented, at least in the early stages, as a system where macro coverage is provided by LTE and 5G radio interface access comes from small cells via aggregation to LTE. In other words, 5G is planned to support both RAT interoperability (such as LTE-5G) and RI interoperability (inter-radio interface interoperability, such as sub-6 GHz – cmWave, 6 or above 24 GHz – cmWave and mmWave). One of the concepts believed to be used in 5G networks is network slicing, in which multiple independent and dedicated virtual subnets (network instances) can be created within the same infrastructure to run services with different requirements for latency, reliability, throughput, and mobility.

[0020] The current architecture in LTE networks is entirely distributed across radios and entirely centralized in the core network. Low-latency applications and services in 5G require content to be closer to the radios, leading to local burst and multi-access edge computing (MEC). 5G enables analytics and knowledge generation to occur at the data source. This approach requires leveraging resources that may not be continuously connected to the network, such as laptops, smartphones, tablets, and sensors. MEC provides a distributed computing environment for hosting applications and services. It also has the ability to store and process content near cellular subscribers to accelerate response times. Edge computing encompasses a wide range of technologies, such as wireless sensor networks, mobile data acquisition, mobile signature analytics, collaborative distributed peer-to-peer self-organizing networks and processing (which can also be categorized as local cloud / fog computing and grid / mesh computing), dew computing, mobile edge computing, small clouds, distributed data storage and retrieval, autonomous and self-healing networks, remote cloud services, augmented and virtual reality, data caching, the Internet of Things (IoT) (massive connectivity and / or latency critical), and critical communications (autonomous vehicles, traffic safety, real-time analytics, time-critical control, healthcare applications).

[0021] The communication system can also communicate with other networks, such as the public switched telephone network, VoIP networks, the Internet, or private networks, or utilize the services provided by them. The communication network may also be able to support the use of cloud services; for example, at least a portion of the core network operation can be performed as a cloud service (this is in...). Figure 1 (Described by “Cloud” 114). The communication system may also include a central control entity that provides facilities for different operators’ networks to cooperate, for example, in spectrum sharing.

[0022] Edge cloud technology can be introduced into the radio access network (RAN) by leveraging Network Functions Virtualization (NFV) and Software-Defined Networking (SDN). Using edge cloud technology means that access node operations are performed, at least partially, in servers, hosts, or nodes that are operationally coupled to remote radio heads or base stations, including the radio portion. Node operations can also be distributed across multiple servers, nodes, or hosts. The application of the cloud RAN architecture enables real-time RAN functions to be performed at or near remote antenna sites (in the distributed unit DU 108) and non-real-time functions to be performed centrally (in the central unit CU 110).

[0023] It should also be understood that the workload allocation between core network operations and base station operations may differ from, or even not exist at all, in LTE. Some other technological advancements that may be used include big data and all-IP, which could potentially change how networks are built and managed. 5G (or New Radio) networks are designed to support multiple hierarchical structures, where MEC servers can be placed between the core and base stations or NodeBs (gNBs). It should be understood that MEC can also be applied to 4G networks.

[0024] 5G can also leverage satellite communications to enhance or supplement the coverage of 5G services, such as by providing backhaul. Possible use cases include providing service continuity for machine-to-machine (M2M) or Internet of Things (IoT) devices or for vehicle passengers, or ensuring the availability of critical communications and future rail / maritime / aviation communications. Satellite communications can utilize geostationary Earth orbit (GEO) satellite systems or low Earth orbit (LEO) satellite systems, particularly mega-constellations (systems deploying hundreds of (nano) satellites). Each satellite in a mega-constellation can cover several satellite-enabled network entities that create a ground cell. Ground cells can be created via ground relay nodes or by gNBs located on the ground or in satellites.

[0025] It will be apparent to those skilled in the art that the depicted system is merely an example of a portion of a radio access system, and in practice, the system may include multiple (e / g) NodeBs that can access multiple radio cells, and may also include other devices such as physical layer relay nodes or other network elements. At least one (e / g) NodeB may be a home (e / g) NodeB. Furthermore, multiple different types of radio cells and multiple radio cells may be provided within the geographical area of ​​the radio communication system. Radio cells may be macrocells (or umbrella cells), which are large cells typically tens of kilometers in diameter, or smaller cells such as micro, femtocells, or picocells. Figure 1 The (e / g)NodeB can provide any type of these cells. Cellular radio systems can be implemented as multi-layer networks comprising several cells. Typically, in a multi-layer network, one access node provides one or more cells, and therefore multiple (e / g)NodeBs are required to provide this network structure.

[0026] To meet the need for improved deployment and performance of communication systems, the concept of "plug and play" (e / g) NodeBs was introduced. Typically, in addition to home (e / g) NodeBs (H(e / g) nodeBs), networks capable of using "plug and play" (e / g) NodeBs also include home NodeB gateways or HNB-GWs ( Figure 1 (Not shown in the image). HNB gateways (HNB-GWs), typically installed within a carrier's network, can aggregate services from a large number of HNBs back to the core network.

[0027] Figure 2 An example of a communication system based on 5G network components is illustrated. A user terminal or user equipment 100 communicates with a data network 112 via a 5G network 202. The user terminal 100 connects to a radio access network (RAN) node, such as (e / g)NodeB 206, which provides connectivity to the network 112 to the user terminal via one or more user plane functions 208. The user terminal 100 also connects to a core access and mobility management function (AMF) 210, which is a control plane core connector for the (radio) access network and can be viewed from this perspective as a 5G version of the mobility management entity (MME) in LTE. The 5G network also includes a session management function (SMF) 212 and a policy control function 214. The SMF 212 is responsible for subscriber sessions, such as session establishment, modification, and release, while the policy control function 214 is configured to manage network behavior by providing policy rules for the control plane functions.

[0028] As mentioned above, in 3GPP, direct communication between a user terminal or terminal equipment that does not go through a RAN node is referred to as a sidelink. In NR sidelinks, two modes are defined: Mode 1 and Mode 2. In Mode 1, the user terminal requests resources from the network for sidelink communication. In Mode 2, the communication equipment selects resources for communication. According to the proposal, the terminal equipment is configured to select the carrier to use in communication based on the Channel Busy Ratio (CBR) measurement. CBR represents congestion on the carrier.

[0029] Note that the carriers mentioned in this document can also be interpreted as resource pools used to support sidelink communication. Therefore, the carrier (re)selection solution mentioned in this document can also be applied to resource pool (re)selection.

[0030] In the existing Mode 2 carrier (re)selection process, the terminal device intending to perform sidelink SL transmission performs a CBR measurement and selects (multiple) candidate carriers based on the CBR measurement result, SL packet priority, and any existing (pre)configuration. If the CBR of a sidelink carrier is lower than a (pre)configured threshold associated with the priority of sidelink transmission, the sidelink carrier is considered a candidate carrier. When more than one candidate carrier is available, the terminal device selects the candidate carrier with the lowest CBR value. A drawback of the current process is that it focuses on the CBR measured at the transmitting terminal device without considering interference / congestion conditions at the receiving terminal device.

[0031] For example, suppose two SL terminal devices transmit SL packets to each other on the carrier with the lowest observed CBR. In this example, the minimum measured CBR at each SL terminal device may be on different carriers, meaning that each SL terminal device may observe different interference / congestion conditions at its location. In this example, the first SL terminal device selects a carrier for transmission that may be severely congested at the location of the second SL terminal device. Correspondingly, the second SL terminal device may select a carrier for transmission that may also be severely congested at the location of the first SL terminal device.

[0032] Figure 3 The flowchart illustrates one embodiment. This flowchart shows an example of the operation of the device. In one embodiment, the device may be a terminal device, part of a terminal device, or any other device capable of performing the following steps. In one embodiment, the device utilizes sidelink communication.

[0033] In step 300, the device is configured to select a carrier for a first transmission to the second device. In one embodiment, the carrier is selected based on CBR measurements of different carriers, which are performed by the device. In another embodiment, a candidate carrier with the lowest CBR value is selected for the first transmission.

[0034] In step 302, the device is configured to control transmission using a selected carrier. In one embodiment, the device may transmit packets or messages to a second device.

[0035] In step 304, the device is configured to receive a transmission from the second device.

[0036] In step 306, the device is configured to select a carrier for a second transmission to the second device based at least in part on the transmission from the second device.

[0037] When selecting a carrier for a second transmission to the second device, the device can take into account the transmission from the second device in various ways.

[0038] Figure 4 This is a signaling diagram illustrating an example. The diagram shows the operation of the first device 100 and the second device 102.

[0039] Both the first and second devices are configured to measure 400 and 402 CBRs across available / configurable carriers.

[0040] The first device is configured to select a carrier for transmission based on CBR measurements. In one embodiment, the candidate carrier with the lowest CBR is selected for transmission 404. In this example, the selected carrier is denoted by C2.

[0041] Next, the first device 100 transmits 406 to the second device 102 using carrier C2.

[0042] The second device 102 is configured to select a carrier for transmission based on CBR measurements. In one embodiment, the candidate carrier with the lowest CBR is selected for transmission 408. In this example, the selected carrier is denoted by C1.

[0043] Next, the second device 102 transmits 410 to the first device 100 using carrier C1.

[0044] The first device 100 is configured to select a carrier 412 for a second transmission based on the transmission 410 of the second device 102. In one embodiment, the first device selects a carrier with the lowest CBR as measured by the second device for the transmission, i.e., the carrier C1 used by the second device in the transmission 410.

[0045] In a similar manner, the second device 102 is configured to select a carrier 414 for a second transmission based on the transmission 406 of the first device 100. In one embodiment, the second device selects a carrier with the lowest CBR as measured by the first device for the transmission, i.e., the carrier C2 used by the first device in transmission 406.

[0046] Next, the first device 100 transmits 416 to the second device 102 using carrier C1, and the second device 102 transmits 418 to the first device 100 using carrier C2.

[0047] Therefore, after the two terminal devices exchange at least one message sequence (i.e., transmissions 406 and 410), both the first and second terminal devices know which carrier has the lowest CBR at their respective receivers. Then, in further message exchanges, both terminal devices are configured to use this information to select the carrier with the lowest CBR at their respective receivers; that is, the first terminal device uses carrier C1 to transmit to the second terminal device, and the second terminal device uses carrier C2 to transmit to the first terminal device.

[0048] Figure 5 This is a signaling diagram illustrating an example. The diagram shows the operation of the first device 100 and the second device 102.

[0049] In this example, the first transmission device 100 randomly selects a carrier for the second transmission between a carrier selected by the second device 102 and an optimal carrier indicated by its own CBR measurement. Furthermore, in one embodiment, it is proposed that this carrier selection is valid only for a certain period of time.

[0050] Figure 5 The first action in the embodiment and Figure 4 The actions are similar.

[0051] Therefore, both the first and second devices are configured to measure 400 and 402 CBRs across available carriers.

[0052] The first device is configured to select a carrier for transmission based on CBR measurements. In one embodiment, the candidate carrier with the lowest CBR is selected for transmission 404. In this example, the selected carrier is denoted by C2.

[0053] Next, the first device 100 transmits 406 to the second device 102 using carrier C2.

[0054] The second device 102 is configured to select a carrier for transmission based on CBR measurements. In one embodiment, the carrier with the lowest CBR is selected for transmission 408. In this example, the selected carrier is denoted by C1.

[0055] Next, the second device 102 transmits 410 to the first device 100 using carrier C1.

[0056] In one embodiment, the first device is configured to set the carrier reselection timer / counter to zero.

[0057] Then, if the first transmission carrier selected by the first device 100 is not the same as the first transmission carrier selected by the second device 102 (i.e., C1 ≠ C2) and the timer / counter has expired, the first device is configured to randomly select 500 between C1 and C2 and restart the timer / counter with a (random) value.

[0058] Similarly, if the first transmission carrier selected by the second device 102 is not the same as the first transmission carrier selected by the first device 100 (i.e., C2 ≠ C1) and the timer / counter has expired, the second device is configured to randomly select 502 between C1 and C2 and restart the timer / counter with a (random) value.

[0059] Next, for example, the first device 100 transmits 504 to the second device 102 using carrier C1 or C2 based on the random selection result at 500, and the second device 102 transmits 506 to the first device 100 using carrier C2 or C1 based on the random selection at 502. After the transmission, the timer / counter is updated. The timer / counter can be used to check whether a random reselection should be triggered.

[0060] Figure 5 The embodiments have the advantage of switching between the optimal carriers of the first device 100 or the second device 102. For example, this can help mitigate any negative impact from the potential fact that the carrier selected by the second device 102 is not optimal for the first device 100 in terms of interference and / or channel congestion.

[0061] In another embodiment, the random selection for transmission on one of the two carriers can be based on a probability influenced by the CBR difference between the two carriers (i.e., one selected by the transmitting device and the other by the receiving device) measured at the transmitting device.

[0062] For example, if the CBR difference measured at the transmitting device is large between two carriers selected by the transmitting and receiving devices respectively, the transmitting device can select a carrier with a high probability based on its own CBR measurement. This is because the transmitting device is unaware of the detailed measurements of the different carriers on the receiving device side. In one embodiment, the CBR difference measured on the receiving device side may be very small, but the transmitting device is unaware of this because the receiving device may not explicitly transmit this information to the transmitting device. The proposed method allows the transmitting device to consider its detailed CBR measurements in order to balance the ratio of packets transmitted on different carriers and avoid high congestion on the carriers selected by the receiving device.

[0063] In one embodiment, the selection of a second transmission carrier can be based on additional feedback from the receiving device. For example, this feedback could be an ACK / NACK message transmitted by the receiving device. In a sidelink, the ACK / NACK feedback from the receiving device can be used to indicate its packet reception status to the transmitting device. In one embodiment, the transmitting device can then trigger a reselection of the transmission carrier based on the content of the Physical Sidelink Feedback Channel (PSFCH) received from the receiving device at the transmitting device during the observation period. Figure 6 This embodiment is shown.

[0064] Figure 6 This is a signaling diagram illustrating an example. The diagram shows the operation of the first device 100 and the second device 102.

[0065] Figure 6 The first action in the embodiment and Figure 4 and Figure 5 The actions are similar.

[0066] Therefore, both the first and second devices are configured to measure 400 and 402 CBRs across available carriers.

[0067] The first device is configured to select a carrier for transmission based on CBR measurements. In one embodiment, the candidate carrier with the lowest CBR is selected for transmission 404. In this example, the selected carrier is denoted by C2.

[0068] Next, the first device 100 transmits 406 to the second device 102 using carrier C2.

[0069] The second device 102 is configured to select a carrier for transmission based on CBR measurements. In one embodiment, the carrier with the lowest CBR is selected for transmission 408. In this example, the selected carrier is denoted by C1.

[0070] The second device 102 transmits 410 to the first device 100 using carrier C1.

[0071] Next, the first device 100 is configured to select carrier 600 for the second transmission based on ACK / NACK messages transmitted by the second device 102. As described above, the ACK / NACK message transmitted by the second device 102 can indicate its reception status for packets transmitted from the first device 100 in 406 via carriers selected, for example, in 404 and / or 600. Similarly, the second device 102 is configured to select carrier 602 for the second transmission based on ACK / NACK messages transmitted by the first device 100.

[0072] Next, the first device 100 transmits 604 to the second device 102 using the selected carrier, and the second device 102 transmits 606 to the first device 100 using the selected carrier.

[0073] In one embodiment, in stage 600, the first device resets the Hybrid Automatic Repeat Request (HARQ) feedback counter with a pre-configured value. For example, the counter value may be (pre-)configured by the network, the terminal device, and / or the implementation, for example, by taking QoS requirements into account. In one embodiment, the device may then update the HARQ feedback counter as follows:

[0074] When the first device receives a NACK from the second device in the Physical Side Link Feedback Channel (PSFCH), it decrements its counter.

[0075] When the first device receives an ACK from the second device in the PSFCH, it increments the counter.

[0076] When communication between the first and second devices is in progress: if the counter reaches zero, a selection is made between C2 (the optimal carrier for the first device) and C1 (the optimal carrier for the second device). In one example, the first device can use its optimal carrier C2 until the counter reaches zero. Then, the first device can switch to the optimal carrier for the second device.

[0077] The above is just one example of a possible way to update the counter.

[0078] It can be noted that when the second device does not transmit the PSFCH (because the second device cannot decode the sidelink control information (SCI) associated with the transmission of the first device), the sidelink radio condition may be worse than when the first device receives a NACK from the second device in the PSFCH, because the SCI is typically transmitted with greater robustness than the data payload. Therefore, the first device may trigger carrier reselection (based on its CBR measurement or based on the carrier used by the second device). Alternatively, when a counter is applied as described above, the absence of PSFCH feedback can be considered as multiple NACKs (e.g., two NACKs).

[0079] Allowing the solution to further rely on the PSFCH or other feedback channels allows the device to more intelligently select between carriers that are measured to be the best carrier for the first device or the second device, so that the first device can accommodate the best carrier for the second device only if the quality of service (QoS) requirements (e.g., reliability) cannot be met.

[0080] In one embodiment, the second device may notify the transmitting first device of the optimal carrier to be used via explicit signaling. For example, this signaling may be triggered whenever the second device determines that the carrier to be used by the transmitting first device has a CBR higher than a (pre)configured threshold, or the number of HARQ NACK feedbacks has reached a threshold, or conditions (e.g., interference, propagation) are unfavorable. In one embodiment, this signaling may be a Specific Media Access Control (MAC) Control Element (CE) payload and / or an RRC message, wherein the second device identifies the carrier (or carrier set) that the transmitting first device should use. Figure 7 This embodiment is shown.

[0081] Figure 7 The first action in the embodiment and Figure 4 The actions are similar.

[0082] Therefore, both the first and second devices are configured to measure 400 and 402 CBRs across available carriers.

[0083] The first device is configured to select a carrier for transmission based on CBR measurements. In one embodiment, the candidate carrier with the lowest CBR is selected for transmission 404. In this example, the selected carrier is denoted by C2.

[0084] Next, the first device 100 transmits 406 to the second device 102 using carrier C2.

[0085] The second device 102 is configured to select a carrier for transmission based on CBR measurements. In one embodiment, the carrier with the lowest CBR is selected for transmission 408. In this example, the selected carrier is denoted by C1.

[0086] The second device 102 is configured to transmit 700 to the first device 100 and notify the optimal carrier with the lowest CBR. The second device may place this information in a MAC CE and / or RRC message. The first device receives from the second device a MAC CE and / or RRC message indicating the optimal carrier (or carrier set) for the peer.

[0087] The first device is configured to select a carrier 702 for a second transmission based at least in part on information received from the second device, and to transmit 704 on the selected carrier. The carrier selection 702 may also take into account CBR measurements at the first device and information received from the second device.

[0088] Figure 8 An embodiment is illustrated. The figure shows a simplified example of a device to which an embodiment of the invention is applied. In some embodiments, the device may be terminal device 100, 102, or part of a terminal device.

[0089] It should be understood that the device described herein is an example illustrating some embodiments. It will be apparent to those skilled in the art that the device may also include other functions and / or structures, and not all described functions and structures are necessary. Although the device is described as a single entity, different modules and memories may be implemented in one or more physical or logical entities.

[0090] The example device 100 includes a control circuit system 800 configured to control at least a portion of the operation of the device.

[0091] The device may include a memory 802 for storing data. Furthermore, the memory may store software 804 executable by the control circuitry system 800. The memory may be integrated into the control circuitry system.

[0092] The device may include one or more interface circuitry systems 806. The interface circuitry systems are operatively connected to the control circuitry system 480. The interface circuitry system 806 may be a set of transceivers configured to communicate with RAN nodes (such as (e / g)NodeBs in a wireless communication network) and other terminal equipment utilizing sidelinks. The interface circuitry system may be connected to an antenna arrangement (not shown). The device may also include connections to transmitters instead of transceivers. The device may also include a user interface.

[0093] In one embodiment, software 804 may include a computer program that includes program code means adapted to cause the control circuitry system 800 of the device to implement at least some of the embodiments described above.

[0094] The steps and related functions described above and in the accompanying figures do not have an absolute temporal order, and some steps may be performed simultaneously or in a different order than given. Other functions may also be performed between or within steps. Some steps may also be omitted or replaced with corresponding steps.

[0095] The apparatus or controller capable of performing the above steps can be implemented as an electronic digital computer, processing system, or circuit system, which may include working memory (random access memory, RAM), a central processing unit (CPU), and a system clock. The CPU may include a set of registers, an arithmetic logic unit, and a controller. The processing system, controller, or circuit system is controlled by a sequence of program instructions transferred from RAM to the CPU. The controller may contain multiple microinstructions for basic operations. The implementation of the microinstructions may vary depending on the CPU design. The program instructions may be encoded in a programming language, which may be a high-level programming language, such as C or Java, or a low-level programming language, such as machine language or assembler. The electronic digital computer may also have an operating system that provides system services to the computer program written with the program instructions.

[0096] As used in this application, the term "circuit system" means all of the following: (a) hardware circuitry implementations only, such as implementations only in analog and / or digital circuitry systems; and (b) combinations of circuitry and software (and / or firmware), such as (if applicable): (i) combinations of (multiple) processors, or (ii) portions of (multiple) processors / software (including (multiple) digital signal processors), software, and (multiple) memories that work together to enable a device to perform various functions; and (c) circuitry, such as (multiple) microprocessors or portions of (multiple) microprocessors that require software or firmware to perform operations, even if the software or firmware does not actually exist.

[0097] This definition of "circuit system" applies to all uses of the term in this application. As another example, as used in this application, the term "circuit system" will also cover only the implementation of a processor (or processors) or a portion thereof and its accompanying software and / or firmware. For example, if applicable to a particular element, the term "circuit system" will also cover baseband integrated circuits or application processor integrated circuits for mobile phones, or similar integrated circuits in servers, cellular network devices, or other network devices.

[0098] An embodiment provides a computer program embodied on a distribution medium, the computer program including program instructions that, when loaded into an electronic device, are configured to control the device to perform the above embodiment.

[0099] Computer programs can be in the form of source code, object code, or some intermediate form, and can be stored on some kind of carrier, which can be any entity or device capable of carrying the program. Such carriers include recording media, computer memory, read-only memory, and software distribution packages. Depending on the required processing power, computer programs can be executed on a single electronic digital computer or distributed among several computers.

[0100] The device can also be implemented as one or more integrated circuits, such as application-specific integrated circuits (ASICs). Other hardware embodiments are also possible, such as circuits constructed from separate logic components. A mixture of these different implementations is also feasible. When selecting an implementation method, those skilled in the art will consider requirements such as device size and power consumption, necessary processing power, production costs, and production volume.

[0101] In one embodiment, an apparatus in a communication system includes components configured to perform the following operations: control a transmission using a selected carrier; receive a transmission from a second apparatus; and select a carrier for a second transmission to the second apparatus based at least in part on the transmission from the second apparatus.

[0102] It will be apparent to those skilled in the art that the concept of this invention can be implemented in various ways as technology advances. The invention and its embodiments are not limited to the examples described above, but can be varied within the scope of the claims.

Claims

1. A terminal device for a communication system, the terminal device comprising: A processor; and a memory including instructions, wherein the instructions, when executed by the processor, cause the terminal device to: Select a carrier for transmission of the first sidechain to the second terminal device; Use the selected carrier to control the sidechain transmission; Receive sidechain transmissions from the second terminal device; Carrier selection for the second sidechain transmission to the second terminal device is based at least in part on the sidechain transmission from the second terminal device; For the second sidechain transmission, the carrier used in the first sidechain transmission or the carrier used by the second terminal device in its transmission is randomly selected. The randomly selected carrier is used based on the probability associated with the channel busy ratio measurement; as well as The random selection is based on a probability associated with the difference in channel busy ratio between the carrier selected by the terminal device and the carrier utilized by the second terminal device based on a channel busy ratio measurement at the terminal device.

2. The terminal device of claim 1, wherein the sidechain transmission received from the second terminal device indicates one or more carriers that the second terminal device considers optimal; and wherein the instruction, when executed by the processor, further causes the terminal device to: For the second transmission, the carrier that the second terminal device considers optimal is selected.

3. The terminal device of claim 1, wherein the sidechain transmission from the second terminal device further includes information regarding the successful / unsuccessful reception of the transmission by the terminal device; and wherein the instruction, when executed by the processor, further causes the terminal device to: Based on the received information, the carrier is selected for the second transmission.

4. The terminal device according to claim 3, wherein the instructions, when executed by the processor, further cause the terminal device to: Receive information about successful / unsuccessful reception on the physical side link feedback channel.

5. The terminal device according to any one of claims 1 to 4, wherein the instructions, when executed by the processor, further cause the terminal device to: Determine the channel busy ratio for a given number of carriers; For the first sidechain transmission to the second terminal device, a carrier with the lowest channel busy ratio is selected.

6. A method for a terminal device in a communication system, the method comprising the following steps: Select a carrier for transmission of the first sidechain to the second terminal device; Use the selected carrier to control the sidechain transmission; Receive sidechain transmissions from the second terminal device; Carrier selection for the second sidechain transmission to the second terminal device is based at least in part on the sidechain transmission from the second terminal device; For the second sidechain transmission, the carrier used in the first sidechain transmission or the carrier used by the second terminal device in its transmission is randomly selected. The randomly selected carrier is used based on the probability associated with the channel busy ratio measurement; as well as The random selection is based on a probability associated with the difference in channel busy ratio between the carrier selected by the terminal device and the carrier utilized by the second terminal device based on a channel busy ratio measurement at the terminal device.

7. A computer program product comprising instructions that, when executed on a terminal device, cause the terminal device to perform at least the following steps: Select a carrier for transmission of the first sidechain to the second terminal device; Use the selected carrier to control the sidechain transmission; Receive sidechain transmissions from the second terminal device; Carrier selection for the second sidechain transmission to the second terminal device is based at least in part on the sidechain transmission from the second terminal device; For the second sidechain transmission, the carrier used in the first sidechain transmission or the carrier used by the second terminal device in its transmission is randomly selected. The randomly selected carrier is used based on the probability associated with the channel busy ratio measurement; as well as The random selection is based on a probability associated with the difference in channel busy ratio between the carrier selected by the terminal device and the carrier utilized by the second terminal device based on a channel busy ratio measurement at the terminal device.

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