Efficient signaling of sidelink radio resources - Patents.com

Abstract

A method for efficient signaling of sidelink radio resources is disclosed. A first terminal device selects a subset of radio resources from a set of candidate radio resources. The first terminal device determines a set of resource indexes for the subset of radio resources based at least in part on a predefined enumeration order of the set of candidate radio resources in time and frequency. The first terminal device determines a first resource indication value indicating at least the set of resource indexes. The first terminal device transmits the first resource indication value to one or more second terminal devices.

Description

[Technical field]

[0001] The following embodiments relate to wireless communications. [Background technology]

[0002] Since resources are limited, it is desirable to optimize the use of resources. In sidelink communication, i.e. device-to-device communication, a terminal device may be exploited to enable better use of resources for communicating with another terminal device. Summary of the Invention

[0003] The scope of protection sought for the various exemplary embodiments is indicated by the independent claims. The exemplary embodiments and features described herein that do not fall within the scope of the independent claims, if any, should be interpreted as examples useful for understanding the various exemplary embodiments.

[0004] According to one aspect, an apparatus is provided comprising at least one processor and at least one memory including computer program code, the at least one memory and the computer program code configured to cause the apparatus to perform, with the at least one processor, the steps of selecting a subset of radio resources from a set of candidate radio resources, determining a set of resource indexes for the subset of radio resources based at least in part on a predefined enumeration order of the set of candidate radio resources in time and frequency, determining a first resource indication value indicative of at least the set of resource indexes, and transmitting the first resource indication value to one or more second terminal devices, the apparatus being included in the first terminal device.

[0005] According to another aspect, an apparatus is provided comprising means for selecting a subset of radio resources from a set of candidate radio resources, determining a set of resource indexes for the subset of radio resources based at least in part on a predefined enumeration order of the set of candidate radio resources in time and frequency, determining a first resource indication value indicative of at least the set of resource indexes, and transmitting the first resource indication value to one or more second terminal devices, the apparatus being configured in a first terminal device.

[0006] According to another aspect, a method is provided comprising the steps of: selecting, by a first terminal device, a subset of radio resources from a set of candidate radio resources; determining, by the first terminal device, a set of resource indexes for the subset of radio resources based at least in part on a predefined enumeration order of the set of candidate radio resources in time and frequency; determining, by the first terminal device, a first resource indication value indicative of at least the set of resource indexes; and transmitting, by the first terminal device, the first resource indication value to one or more second terminal devices.

[0007] According to another aspect, a computer program is provided, comprising instructions for causing an apparatus to perform at least the steps of: selecting a subset of radio resources from a set of candidate radio resources; determining a set of resource indexes for the subset of radio resources based at least in part on a predefined enumeration order of the set of candidate radio resources in time and frequency; determining a first resource indication value indicative of at least the set of resource indexes; and transmitting the first resource indication value to one or more second terminal devices, the apparatus being included in a first terminal device.

[0008] According to another aspect, a computer-readable medium is provided, comprising program instructions for causing an apparatus to perform at least the steps of selecting a subset of radio resources from a set of candidate radio resources; determining a set of resource indexes for the subset of radio resources based at least in part on a predefined enumeration order of the set of candidate radio resources in time and frequency; determining a first resource indication value indicative of at least the set of resource indexes; and transmitting the first resource indication value to one or more second terminal devices, wherein the apparatus is included in a first terminal device.

[0009] According to another aspect, a non-transitory computer-readable medium is provided, the medium including program instructions for causing an apparatus to perform at least the steps of selecting a subset of radio resources from a set of candidate radio resources, determining a set of resource indexes for the subset of radio resources based at least in part on a predefined enumeration order of the set of candidate radio resources in time and frequency, determining a first resource indication value indicative of at least the set of resource indexes, and transmitting the first resource indication value to one or more second terminal devices, the apparatus being included in a first terminal device.

[0010] According to one aspect, an apparatus is provided comprising at least one processor and at least one memory including computer program code, the at least one memory and the computer program code configured to cause the apparatus, using the at least one processor, to perform the steps of receiving a resource indication from a first terminal device, the resource indication indicating at least a set of resource indexes related to a subset of radio resources, a resource index within the set of resource indexes indicating a location of a radio resource included in the subset of radio resources in time and frequency, determining a subset of radio resources from a set of candidate radio resources based at least in part on the resource indication, and selecting a radio resource from the subset of radio resources for a sidelink transmission, the apparatus being included in a second terminal device.

[0011] According to another aspect, an apparatus is provided, comprising means for receiving a resource indication from a first terminal device, the resource indication indicating at least a set of resource indexes associated with a subset of radio resources, a resource index within the set of resource indexes indicating a position of a radio resource included in the subset of radio resources in time and frequency, determining a subset of radio resources from a set of candidate radio resources based at least in part on the resource indication, and selecting a radio resource from the subset of radio resources for a sidelink transmission, the apparatus being comprised in a second terminal device.

[0012] According to another aspect, a method is provided comprising the steps of: receiving, by a second terminal device, a resource indication value from the first terminal device, the resource indication value indicating at least a set of resource indexes associated with a subset of resources; determining, by the second terminal device, a subset of resources from a set of candidate resources based at least in part on the resource indication value; and selecting, by the second terminal device, a resource from the subset of resources for a sidelink transmission.

[0013] According to another aspect, there is provided a computer program comprising instructions for causing an apparatus to perform at least the steps of: receiving a resource indication from a first terminal device, the resource indication indicating at least a set of resource indexes associated with a subset of radio resources, a resource index within the set of resource indexes indicating a position of a radio resource included in the subset of radio resources in time and frequency; determining a subset of radio resources from a set of candidate radio resources based at least in part on the resource indication; and selecting a radio resource from the subset of radio resources for a sidelink transmission, the apparatus being comprised in a second terminal device.

[0014] According to another aspect, a computer-readable medium is provided, comprising program instructions for causing an apparatus to perform at least the steps of: receiving a resource indication from a first terminal device, the resource indication indicating at least a set of resource indexes associated with a subset of radio resources, a resource index within the set of resource indexes indicating a location of a radio resource included in the subset of radio resources in time and frequency; determining a subset of radio resources from a set of candidate radio resources based at least in part on the resource indication; and selecting a radio resource from the subset of radio resources for a sidelink transmission, the apparatus being included in a second terminal device.

[0015] According to another aspect, a non-transitory computer-readable medium is provided, comprising program instructions for causing an apparatus to perform at least the steps of: receiving a resource indication from a first terminal device, the resource indication indicating at least a set of resource indexes associated with a subset of radio resources, a resource index within the set of resource indexes indicating a location of a radio resource included in the subset of radio resources in time and frequency; determining a subset of radio resources from a set of candidate radio resources based at least in part on the resource indication; and selecting a radio resource from the subset of radio resources for a sidelink transmission, the apparatus being included in a second terminal device.

[0016] According to another aspect, a system is provided comprising at least a first terminal device and a second terminal device, the first terminal device is configured to select a subset of radio resources from a set of candidate radio resources, determine a set of resource indexes for the subset of radio resources based at least in part on a predefined enumeration order of the set of candidate radio resources in time and frequency, determine a resource indication value indicative of at least the set of resource indexes, and transmit the resource indication value to the second terminal device, the second terminal device is configured to receive the resource indication value from the first terminal device, determine a subset of radio resources from the set of candidate radio resources based at least in part on the resource indication value, and select a radio resource from the subset of radio resources for sidelink transmission.

[0017] According to another aspect, a system is provided comprising at least a first terminal device and a second terminal device. The first terminal device comprises means comprising the steps of selecting a subset of radio resources from a set of candidate radio resources, determining a set of resource indexes for the subset of radio resources based at least in part on a predefined enumeration order of the set of candidate radio resources in time and frequency, determining a resource indication value indicative of at least the set of resource indexes, and transmitting the resource indication value to the second terminal device. The second terminal device comprises means comprising the steps of receiving the resource indication value from the first terminal device, determining a subset of radio resources from the set of candidate radio resources based at least in part on the resource indication value, and selecting a radio resource from the subset of radio resources for a sidelink transmission.

[0018] Various exemplary embodiments are described in more detail below with reference to the accompanying drawings. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 illustrates an exemplary embodiment of a cellular communication network. [Diagram 2] FIG. 2 illustrates sidelink radio resource allocation coordination between terminal devices. [Diagram 3] FIG. 3 shows an example showing two reserved radio resources. [Figure 4] FIG. 4 illustrates a flow chart according to an example embodiment. [Diagram 5] FIG. 5 shows an example of encoding the determined resource size. [Figure 6] FIG. 6 illustrates a flow chart according to some example embodiments. [Figure 7] FIG. 7 illustrates a flowchart according to some example embodiments. [Figure 8] FIG. 8 illustrates a flowchart according to some example embodiments. [Figure 9] FIG. 9 shows a signaling diagram according to an example embodiment. [Figure 10] FIG. 10 illustrates an apparatus according to an exemplary embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The following embodiments are illustrative. Although the specification may refer to "an," "one," or "some" embodiments in several places in the text, this does not necessarily mean that each reference is to the same embodiment or that a particular feature applies only to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.

[0021] In the following, various exemplary embodiments are described using radio access architectures based on Long Term Evolution Advanced (LTE-A) or New Radio (NR, 5G) as examples of access architectures to which the exemplary embodiments may be applied, but the exemplary embodiments are not limited to such architectures. For example, some exemplary embodiments may be applied to sidelink communication over a PC5 air interface and / or uplink / downlink over a Uu interface. As will be apparent to those skilled in the art, the exemplary embodiments may also be applied to other types of communication networks having suitable means by appropriately adjusting parameters and procedures. Some examples of other options for suitable systems may be Universal Mobile Telecommunications System (UMTS) Radio Access Networks (UTRAN or E-UTRAN), Long Term Evolution (LTE, substantially the same as E-UTRA), Wireless Local Area Networks (WLAN or Wi-Fi), Worldwide Interoperability for Microwave Access (WiMAX), Bluetooth, Personal Communications Services (PCS), ZigBee, Wideband Code Division Multiple Access (WCDMA), systems using ultra-wideband (UWB) technology, sensor networks, Mobile Ad-Hoc Networks (MANET), and Internet protocol Multimedia Subsystems (IMS), or any combination thereof.

[0022] 1 shows an example of a simplified system architecture showing several elements and functional entities, all of which are logical units, whose implementation may differ from that shown. The connections shown in FIG. 1 are logical connections, and the actual physical connections may differ. As would be apparent to one skilled in the art, the system may also comprise functions and structures other than those shown in FIG. 1.

[0023] However, the exemplary embodiment is not limited to the system given as an example, and a person skilled in the art can apply the solution to other communication systems that have the required characteristics.

[0024] The example of FIG. 1 illustrates a portion of an exemplary radio access network.

[0025] 1 shows user devices 100 and 102 configured to be in wireless connection over one or more communication channels in a cell with an access node (e.g., (e / g)NodeB) 104 serving the cell. The physical link from the user device to the (e / g)NodeB may be referred to as an uplink or reverse link, and the physical link from the (e / g)NodeB to the user device may be referred to as a downlink or forward link. It should be understood that the (e / g)NodeB or their functionality may be implemented by using any node, host, server or access point, etc. entity suitable for such use.

[0026] The communication system may comprise multiple (e / g)NodeBs, in which case the (e / g)NodeBs may also be configured to communicate with each other via wired or wireless links designed for that purpose. These links may be used for signaling purposes. The (e / g)NodeB may be a computing device configured to control radio resources of the communication system to which it is coupled. The NodeB may also be called a base station, an access point, or any other type of interface device including a relay station capable of operating in a wireless environment. The (e / g)NodeB may include or be coupled to a transceiver. A connection may be provided from the transceiver of the (e / g)NodeB to an antenna unit that establishes a bidirectional wireless link to a user device. The antenna unit may comprise multiple antennas or antenna elements. The (e / g)NodeB may further be connected to a core network 110 (CN: Core Network or Next Generation Core (NGC)). Depending on the system, the counterpart on the CN side may be a Serving Gateway (S-GW, routing and forwarding of user data packets), a Packet data network Gateway (P-GW) for providing connectivity of a User Device (UE) to an external packet data network, or a Mobile Management Entity (MME), etc.

[0027] A user device (also referred to as UE, user equipment, user terminal, terminal device, etc.) denotes one type of device to which radio resources over the air interface may be allocated and assigned, and thus any features described herein with respect to a user device may be implemented in a corresponding device such as a relay node. An example of such a relay node may be a Layer 3 relay (self-backhaul relay) towards a base station.

[0028] User devices refer to portable computing devices including wireless mobile communication devices that operate with or without a Subscriber Identification Module (SIM), including but not limited to these types of devices: mobile stations (cell phones), smartphones, personal digital assistants (PDAs), handsets, devices that use wireless modems (such as alarms or measuring devices), laptops and / or touch screen computers, tablets, game consoles, notebooks, and multimedia devices. It should be understood that user devices may also be almost exclusively uplink-only devices, an example of which may be a camera or video camera that loads images or video clips onto the network. User devices may also be devices capable of operating in Internet of Things (IoT) networks, which is a scenario in which objects may be provided with the ability to transfer data over a network without the need for human-to-human or human-to-computer interaction. User devices may also utilize the cloud. In some applications, user devices may comprise small portable devices with wireless components (such as watches, earphones or glasses) and computations may be performed in the cloud. A user device (or in some exemplary embodiments a Layer 3 relay node) may be configured to perform one or more of the user equipment functions. A user device may also be called a subscriber unit, mobile station, remote terminal, access terminal, user terminal, terminal device or user equipment (UE), to mention just a few names or devices.

[0029] The various techniques described herein may also be applied to Cyber ​​Physical Systems (CPS), systems that cooperate with computational elements to control physical entities. CPS may enable the implementation and utilization of a large number of interconnected ICT devices (sensors, actuators, processors, microcontrollers, etc.) embedded in physical objects in different locations. Mobile Cyber ​​Physical Systems, where the physical system in question has inherent mobility, are a subcategory of Cyber ​​Physical Systems. Examples of mobile physical systems include mobile robots and electronic devices transported by humans or animals.

[0030] Furthermore, although the apparatus is shown as a single entity, it may be implemented with different units, processors and / or memory units (not all of which are shown in FIG. 1).

[0031] 5G may enable the use of multiple input multiple output (MIMO) antennas, many more base stations or nodes than LTE (so-called small cell concept), including macro sites that work in cooperation with smaller stations and use different radio technologies depending on the service needs, use cases, and / or available spectrum. 5G mobile communications may support a wide range of use cases and related applications, including video streaming, augmented reality, different ways of data sharing, and various forms of machine type applications (such as (massive) machine type communications (mMTC)), including vehicle safety, different sensors, and real-time control. 5G has multiple air interfaces, namely sub-6 GHz, cmWave, and mmWave, and may also be expected to be integrable with existing legacy radio access technologies such as LTE. Integration with LTE may be implemented as a system, at least in the initial stages, where macro coverage may be provided by LTE and 5G air interface access may be from small cells by aggregation to LTE. In other words, 5G can support both inter-RAT operation (such as LTE-5G) and inter-RI operation (inter-air interface operation such as sub-6 GHz, cmWave, mmWave, etc.). One concept likely to be used in 5G networks may be network slicing, where multiple independent and dedicated virtual sub-networks (network instances) may be created within substantially the same infrastructure to run services with different requirements for latency, reliability, throughput and mobility.

[0032] The current architecture in LTE networks may be fully distributed in the radio or fully centralized in the core network. Low latency applications and services in 5G may require content to be closer to the radio, which leads to local breakout and Multi-access Edge Computing (MEC). 5G may allow analytics and knowledge generation to take place at the source of the data. This approach may require leveraging resources that may not be continuously connected to the network, such as laptops, smartphones, tablets, and sensors. MEC can provide a distributed computing environment for application and service hosting. It may also have the ability to store and process content in close proximity to the cellular subscriber for faster response times. Edge computing can cover a wide range of technologies such as wireless sensor networks, mobile data acquisition, mobile signature analysis, collaborative distributed peer-to-peer ad-hoc networking and processing which can also be categorized as local cloud / fog computing and grid / mesh computing, dew computing, mobile edge computing, cloudlets, distributed data storage and retrieval, autonomous self-healing networks, remote cloud services, augmented and virtual reality, data caching, Internet of Things (massive connectivity and / or latency critical), critical communications (autonomous vehicles, road safety, real-time analytics, time-critical control, healthcare applications), etc.

[0033] The communications system may also be capable of communicating with or using services provided by other networks, such as the Public Switched Telephone Network or the Internet 112. The communications network may also be capable of supporting the use of cloud services, e.g., at least a portion of the core network operations may be performed as a cloud service (this is illustrated in FIG. 1 by "the cloud" 114). The communications system may also comprise a central control entity, etc., that provides facilities for networks of different operators to cooperate, e.g., in spectrum sharing.

[0034] Edge cloud is brought to Radio Access Network (RAN) by utilizing Network Function Virtualization (NFV) and Software Defined Networking (SDN). Using edge cloud may mean that access node operations are performed at least in part in a server, host, or node operably coupled to a remote radio head or base station comprising a radio component. Node operations may also be distributed among multiple servers, nodes, or hosts. Application of cloudRAN architecture may enable RAN real-time functions to be performed on the RAN side (on the distributed unit (DU 104) side) and non-real-time functions to be performed in a centralized manner (on the central unit (CU 108)).

[0035] It should also be understood that the distribution of labor between core network operations and base station operations may be different from that of LTE or may even not exist. Some other technology advances that may be used may be big data and all-IP, which may change the way networks are built and managed. 5G (or New Radio (NR)) networks may be designed to support multiple hierarchies, and MEC servers may be located between the core and base stations or nodeBs (gNBs). It should be understood that MEC may also be applied in 4G networks.

[0036] 5G can also utilize satellite communications to enhance or complement the coverage of 5G services, for example by providing backhaul. Possible use cases can be to provide service continuity to machine-to-machine (M2M) or Internet of Things (IoT) devices or passengers on board vehicles, or to ensure service availability for critical communications and future rail / maritime / aeronautical communications. Satellite communications can utilize Geostationary Earth Orbit (GEO) satellite systems, but also Low Earth Orbit (LEO) satellite systems, especially megaconstellations (systems in which many (nano)satellites are deployed). At least one satellite 106 in the megaconstellation can cover several satellite-enabled network entities creating ground cells. The ground cells can be created via terrestrial relay nodes 104 or by gNBs located on the ground or in the satellites.

[0037] It is clear to those skilled in the art that the illustrated system is only a part of an example of a radio access system, and in reality the system may include multiple (e / g)NodeBs, a user device may have access to multiple radio cells, and the system may also include other devices such as physical layer relay nodes or other network elements. At least one of the (e / g)NodeBs may be a Home(e / g)NodeB. Also, a geographical area of ​​the radio communication system may be provided with multiple radio cells of different types as well as multiple radio cells. The radio cells may be macrocells (or umbrella cells), which may be large cells with a diameter of up to tens of kilometers, or smaller cells such as microcells, femtocells, or picocells. The (e / g)NodeBs in FIG. 1 may provide any type of these cells. The cellular radio system may be implemented as a multi-layer network including several types of cells. In a multi-layer network, one access node may provide one type of cell, and therefore multiple (e / g)NodeBs may be required to provide such a network structure.

[0038] To meet the demands of improving the deployment and performance of communication systems, the concept of "plug-and-play" (e / g) NodeB can be introduced. A network that can use "plug-and-play" (e / g) NodeB can include a home nodeB gateway (or HNB-GW) (not shown in FIG. 1) in addition to the Home(e / g)NodeB (H(e / g)nodeB). The HNB gateway (HNB-GW), which can be installed in an operator's network, can aggregate traffic from multiple HNBs back to the core network.

[0039] Sidelink communication enables direct communication between UEs, relaying traffic between the network and the UE or between two UEs via a relay UE. NR sidelink may support advanced vehicle-to-everything (V2X) communication services such as sensor sharing, as well as Proximity Services (ProSe) communication, for example. NR sidelink transmissions may occur, for example, in a Physical Sidelink Shared Channel (PSSCH). In NR sidelink mode 1, radio resources for PSSCH transmissions may be scheduled by a base station, such as a gNB. In NR sidelink mode 2, radio resources for PSSCH transmissions may be selected autonomously by the UE.

[0040] 2 illustrates inter-UE cooperation for NR sidelink mode 2 resource allocation. A set of radio resources is determined by a first UE 201. The set of radio resources is transmitted (210) to a second UE 202. The second UE 202 then takes this set of radio resources into account in resource selection for its own PSSCH transmission.

[0041] Such inter-UE cooperation may be used, for example, when a first UE acts as a group leader by coordinating the radio resources used by other UEs in the group, such as in a platoon. Another example use case may be, for example, receiver-assisted resource selection in unicast sidelink communication, where the receiver UE indicates its preferred or non-preferred radio resources to the transmitter UE. This may be used, for example, as a way to address the hidden terminal problem, where the receiver UE is exposed to an interference source that is not detectable by the transmitter UE.

[0042] In Rel-16 NR sidelink, the first stage sidelink control information (SCI) may comprise resource allocation information for reserving up to k=2 radio resources in a time window containing T=31 logical slots of a resource pool starting from the logical slot next to the logical slot in which the SCI is transmitted, as shown in Figure 3. Figure 3 shows an example illustrating two reserved radio resources indicated by SCI format 1-A.

[0043] The resource allocation information carried by SCI Format 1-A includes two fields: a time resource allocation in the form of a Time Resource Indication Value (TRIV) and a frequency resource allocation in the form of a Frequency Resource Indication Value (FRIV).

[0044] The TRIV field indicates the logical slot offset of the reserved resource relative to the slot in which the SCI is transmitted. For two reserved resources (k=2), two offsets t1 and t2 (t1 ≥ 1 and < t2, t2 ≥ t1 and < 31) are coded by the TRIV field as follows:

number

[0045] In FIG. 3, offset t1 is indicated by section 301 and offset t2 is indicated by section 302.

number

number

[0046] The FRIV field indicates the starting subchannel index of the reserved resources within the resource pool, and the total shown in Figure 3 by interval 303

Number

Number

Number

Number

[0047] In Figure 3,

Number

Number

Number

Number

[0048] The above TRIV and FRIV formulas are applicable for k = 2. The FRIV formula can be generalized as follows for any number of indicated radio resources k. [Number]

[0049] The FRIV field in this case [Number] results in bits of overhead.

[0050] However, the TRIV formula may not allow generalization for k > 2. As described above, since t1 < t2, a further limitation of the TRIV formula is that the indicated resources are not in the same slot. Further, the limitation of the FRIV formula is that all radio resources are assumed to have the same resource size L subCH Therefore, the TRIV and FRIV techniques used in SCI format 1 - A are not applicable for signaling any arbitrary radio resource set.

[0051] Some exemplary embodiments may be used to efficiently encode any number of radio resources determined by a first UE, for example, to minimize control signaling overhead for UE - to - UE cooperation in NR sidelink mode 2 resource allocation. Some exemplary embodiments may comprise a method for signaling a set of radio resources from a first UE to one or more second UEs with minimal overhead.

[0052] Some example embodiments may utilize a k-th order combinatorial number system. In mathematics, a k-th order combinatorial number system is a correspondence between natural numbers (including 0) and k combinations, i.e., subsets of k distinct elements.

number

number

number

[0053] This operation is known in computational mathematics as "ranking". The inverse operation, known as "unranking", i.e., finding the k combinations {c1, c2,..., ck} corresponding to a number N, can be performed by a greedy algorithm as follows: First, ck is

number

number

[0054] FIG. 4 shows a flow chart according to an exemplary embodiment. Referring to FIG. 4, the first UE determines a set of candidate radio resources for PSSCH transmission by one or more second UEs (step 401). The first UE selects a subset of radio resources from the set of candidate radio resources (step 402). The first UE determines a set of resource indexes for the subset of selected radio resources based at least in part on a predefined enumeration order of the set of candidate radio resources in the time domain and the frequency domain (step 403). Based on the determined resource indexes, the first UE determines a resource indication value, e.g., a combined resource indication value (CRIV), indicating the subset of selected radio resources (step 404). The CRIV includes both time domain information and frequency domain information. The first UE transmits the determined resource indication value to one or more second UEs (step 405).

[0055] The step 401 of determining a set of candidate radio resources may for example be triggered by the first UE receiving a Coordination Request (CR), a Scheduling Request (SR) or a Buffer Status Report (BSR) from one or more second UEs. The candidate radio resources for the transmission of the PSSCH may be defined by time domain resources, i.e. one or more slots and / or frequency domain resources, i.e. one or more subchannels. The first UE may determine the set of candidate radio resources based on for example the received BSR, channel conditions, etc., the resource size L subCH , i.e., the length of consecutive subchannels in the frequency domain. For example, a high buffer level or a bad channel condition may cause the first UE to consider a large radio resource, while a low buffer level or a good channel condition may cause the first UE to consider a small radio resource. Thus, the set of candidate radio resources may be constrained by the determined resource size.

[0056] The set of candidate radio resources may be further constrained by a sidelink radio resource pool configured for the transmission of the PSSCH by the second UE. In other words, the candidate radio resources may be limited to resources in the resource pool. The first UE may be assumed to be aware of the resource pool of the second UE, e.g., if the first UE is also configured with the same resource pool or if the first UE is under the control of the resource pool of the second UE. Alternatively, the second UE may inform the first UE of its resource pool, e.g., when requesting radio resources from the first UE.

[0057] Similarly, the set of candidate radio resources may be constrained by a time interval, i.e., Resource Selection Window (RSW), imposed by the requirement to meet a predefined packet delay budget. In other words, the candidate radio resources may be limited to resources within a time interval. Such RSW may be determined by the first UE based on the time, e.g., slot, at which a CR, SR, or BSR is received from the second UE and / or a packet delay budget predefined or indicated by the second UE. The RSW may also be predefined or configured.

[0058] For example, a first UE may select a sidelink radio resource pool of resource size L with T logical slots of the sidelink radio resource pool configured for PSSCH transmission by a second UE. subcH If determining RSW and RSW, the set of candidate radio resources may comprise the sum of:

number

number

[0059] The selecting step 402 involves selecting a subset of k radio resources from the set of n candidate radio resources, where the number k of selected radio resources in the subset may be configured by the network, i.e., the base station, for example by using a Radio Resource Control (RRC) message, or the number k may be derived by the first UE. For example, the number k may be a predefined percentage of the number of candidate radio resources, for example 10%.

[0060] The first UE may select the subset of radio resources based on sensing measurements, such as Reference Signal Received Power (RSRP) and / or Received Signal Strength Indicator (RSSI), performed by the first UE, for example. For example, the subset of radio resources may comprise preferred and / or non-preferred radio resources from the perspective of the first UE as an intended receiver of a subsequent PSSCH transmission by one or more second UEs.

[0061] The k selected radio resources are of the same size, e.g., L subCH Alternatively, the selected radio resources may have different resource sizes. For example, the jth selected radio resource (j is 1 to k) may be L subCH,j The channel may comprise consecutive sub-channels.

[0062] For the step 403 of determining a resource index rj for the j-th selected radio resource, j ≥ 1 and <= k, the resource index can be

number

[0063] For example, a resource index rj for the jth selected radio resource (j ≥ 1 and ≤ k) may be determined as follows:

number

number

number

[0064] Alternatively, the resource index rj for the jth selected radio resource (j ≥ 1 and ≤ k) may be determined as follows:

number

number

[0065] [Table 1]

[0066] [Table 2]

[0067] Upon determining resource indices rj for the k selected radio resources, where j is 1 to k, the first UE may:

number

number

number

[0068] For example, in the case shown in Table 1, n = 40, k = 5, the determined resource index is {r1, r2, r3, r4, r5} = {6, 19, 22, 30, 37}, and the rank of the 5 combinations {r1, r2, r3, r4, r5} is

number

[0069] The rank R determined according to the above formula does not convey information about the resource size L determined by the first UE. subCH Note that Figure 5 shows an example of how the resource size L subCH can affect the number of candidate radio resources, and as a result, shows the number of possible ways to select k radio resources from among them.

Number

Number

Number

[0070] In the first example 501, when the resource size L subCH = 1, the number of ways to select k radio resources from among n1 candidate radio resources is

Number

Number

Number

number

number

number

[0071] Thus, the first UE may encode the selected subset of radio resources as a CRIV;

number

number

[0072] In this manner, the first UE may use a single integer value, i.e., CRIV, to determine the determined set of radio resource indices {r1, r2, . . . , rk} (encoded by rank R) and the resource size L subCH (encoded by sum terms) can be jointly represented as

number

number

[0073] The series terms in the above CRIV formula are the RSW and the determined resource size L in the configured sidelink resource pool. subCHThe kth radio resource selection method can be seen as an offset corresponding to the total number of possible ways to select the smaller kth radio resource. With a single CRIV, the determined set of resource indices and the resource size L subCH An alternative way to show both is to use the determined resource size L subCH by using an offset corresponding to the total number of possible ways of selecting the larger k radio resources, i.e.

number

[0074] The determined CRIV indicating the selected subset of radio resources may be transmitted (405) to one or more second UEs, for example by using physical layer signaling, such as a first stage SCI or a second stage SCI, or by using higher layer signaling, such as a Medium Access Control (MAC) Control Element (CE) or an RRC message. When using an RRC message to carry the CRIV, a possible Abstract Syntax Notation One (ASN.1) representation of the message may be, for example, the following:

number

[0075] In some exemplary embodiments, the resource size L subCH may be predefined or configured such that there is no need to signal to the second UE or UEs. In this case, CRIV may be set equal to the determined rank, i.e., CRIV=R. For R

number

number

[0076] In some demonstrative embodiments, as in Tables 1 and 2 above, when the selected radio resources do not overlap in time, i.e., they occur in different slots, the first UE may determine the rank R′ based on the time domain information, for example, as follows:

number

number

number

[0077] In this case, the time domain information may be conveyed to the second UE by a TRIV field equal to the determined rank, i.e. TRIV=R′, with overhead of

number

[0078] Frequency domain information, if applicable, may be conveyed by using a separate FRIV field based on the generalized FRIV formula.

number

number

number

number

[0079] In some exemplary embodiments, the first UE selects a different resource size L for at least some of the selected radio resources. subCH,j When determining, the first UE may signal different resource sizes to one or more second UEs, for example, by a resource length indication value (LIV) as follows:

number

[0080] Therefore, for LIV

number

number

[0081] Alternatively, if separate TRIV and FRIV fields are used to convey time domain and frequency domain information, respectively, the resource size L subCH,j are the starting subchannel indexes of each

number

number

number

number

[0082] From the received FRIV value, the second UE may obtain frequency domain information, for example, as follows:

number

[0083] 6 shows a flow chart according to an example embodiment, in which a first UE determines a second resource indication indicating at least a plurality of resource sizes associated with a subset of radio resources (step 601). The second resource indication may be, for example, a LIV or a FRIV according to the generalized FRIV formula presented above. The first UE transmits the second resource indication to one or more second UEs (step 602).

[0084] 7 shows a flow chart according to another example embodiment, in which a first UE transmits a permutation index indicating a permutation of a subset of radio resources to one or more second UEs (step 701). In other words, the first UE may indicate a permutation, i.e., ordering, of the selected subset of radio resources to one or more second UEs. The permutation may be indicated by a permutation index P, which may be greater than or equal to 0 and less than k!. Since there may be k! permutations of the selected subset of radio resources, this may be expressed as:

number

[0085] FIG. 8 shows a flowchart according to an exemplary embodiment from the perspective of a second UE. Referring to FIG. 8, the second UE receives a resource indication value, e.g., a CRIV, from the first UE indicating at least a set of resource indexes associated with a subset of radio resources (step 801). The resource indexes in the set of resource indexes indicate the location of the radio resources included in the subset of radio resources in the time domain and the frequency domain. The second UE determines a set of candidate radio resources for the transmission of the PSSCH (step 802). The second UE determines a subset of selected radio resources from the set of candidate radio resources based on the received CRIV (step 803). The second UE selects one or more radio resources from the determined subset of selected radio resources for the PSSCH transmission (step 804).

[0086] The second UE may receive a CRIV from the first UE (step 801), for example, by using physical layer signaling in an SCI or by using higher layer signaling, for example, in a MAC CE or RRC message.

[0087] The set of candidate radio resources determined by the second UE in step 802 may be substantially the same as the set of candidate radio resources determined by the first UE. The second UE may determine a RSW substantially the same as the RSW determined by the first UE based on the time, e.g., slot, at which the CRIV is received from the first UE, e.g., based on the slot at which the SCI including the CRIV is received. For example, the RSW may start a predefined number of slots after the first UE to give the second UE sufficient time to prepare the data to be transmitted. If not predefined, such a slot offset may be indicated by the first UE to the second UE, e.g., together with the CRIV. The second UE may also determine the RSW based on the time, e.g., slot, at which the second UE transmitted a CR, SR or BSR to the first UE and / or the packet delay budget of the data transmitted by the second UE. Alternatively, the RSW may be predefined or configured.

[0088] The second UE determines the resource size L based on the received CRIV. subCH can be determined, for example, as follows:

number

number

[0089] As another example, a resource size of L subCH can be determined as follows:

number

[0090] Alternatively, the resource size L subCH can be predefined or configured.

[0091] A determined or predefined RSW and a determined or predefined resource size L subCH Based on the determined set of candidate radio resources in the configured sidelink radio resource pool for the PSSCH transmission by the second UE, the second UE may determine a set of candidate radio resources in the configured sidelink radio resource pool for the PSSCH transmission by the second UE. As mentioned above, the set of candidate radio resources determined by the second UE may be substantially the same as the set of candidate radio resources determined by the first UE.

[0092] In step 803 of determining a subset of radio resources selected based on the received CRIV, the second UE determines the determined resource size L subCH Based on this, we can recover the rank R of the k combinations {r1, r2, rk}.

number

[0093] As another example, the rank R can be determined as follows:

number

[0094] The second UE may then determine resource index {r1, r2, . . . , rk} from the recovered rank R based on a greedy algorithm, for example, as follows:

number

number

[0095] Based on the determined resource index rj for a given radio resource j among the k selected radio resources, where j is 1 to k, the second UE determines a logical slot offset tj and a starting subchannel index of the j-th selected radio resource within the RSW and the configured sidelink radio resource pool.

number

number

[0096] Alternatively, if we assume that we first enumerate the candidate radio resources by considering the frequency domain, these indices can be, for example,

number

[0097] The second UE may select one or more radio resources for transmission of the PSSCH from the determined subset of selected radio resources indicated by the first UE (step S804). For example, the second UE may select one or more radio resources for transmission of the PSSCH from the determined subset of selected radio resources indicated by the first UE based on sensing measurements, such as RSRP and / or RSSI, performed by the second UE.

[0098] Figure 9 shows a signaling diagram according to an example embodiment. Referring to Figure 9, a first UE (denoted as UE1) transmits a message including a resource indication value, e.g., CRIV, to a second UE (denoted as UE2) (step 901). The second UE decodes the resource index and selects radio resources for PSSCH transmission based on the received CRIV (step 902). The second UE transmits a PSSCH transmission to the first UE using at least the selected radio resources (step 903).

[0099] Alternatively, the second UE may send a PSSCH transmission to the third UE (on behalf of the first UE) by using at least the selected radio resource.

[0100] The functions and / or blocks described above with reference to Figures 4 and 6-9 are not in absolute chronological order, and some of them may be performed simultaneously or in a different order than the order described. Other functions and / or blocks may also be performed between or within them.

[0101] A technical advantage provided by some exemplary embodiments is that they may provide an efficient way to signal an arbitrary set of radio resources within a resource selection window and a configured sidelink radio resource pool, e.g., for UE-to-UE coordination in NR sidelink mode 2 resource allocation. Here, efficiency means reduced bit overhead. Compared to the legacy TRIV and FRIV techniques used in SCI format 1-A, which are limited to a maximum of k=2 selected radio resources, the CRIV approach provided by some exemplary embodiments may be used to signal any number of selected radio resources. Since CRIV jointly encodes the time-domain and frequency-domain locations of the selected radio resources and a given CRIV value corresponds to a unique and valid selection of these variables, the CRIV approach results in minimal bit overhead. Furthermore, some exemplary embodiments may allow the selected radio resources to overlap in time.

[0102] In some exemplary embodiments, signaling CRIV comprises:

number

number

number

number

[0103] [Table 3]

[0104] To provide a fair comparison, we generalize the overhead incurred by TRIV for k radio resources.

number

[0105] FIG. 10 illustrates an apparatus 1000 that may be an apparatus such as a terminal device or included in a terminal device, according to an example embodiment. The terminal device may also be referred to herein as a UE. The apparatus 1000 comprises a processor 1010. The processor 1010 interprets computer program instructions and processes data. The processor 1010 may comprise one or more programmable processors. The processor 1010 may comprise programmable hardware with embedded firmware, or alternatively or additionally may comprise one or more Application Specific Integrated Circuits (ASICs).

[0106] The processor 1010 is coupled to the memory 1020. The processor is configured to read and write data to and from the memory 1020. The memory 1020 may comprise one or more memory units. The memory units may be volatile or non-volatile. It is noted that in some exemplary embodiments, there may be one or more units of non-volatile memory and one or more units of volatile memory, or one or more units of non-volatile memory, or one or more units of volatile memory. The volatile memory may be, for example, a Random-Access Memory (RAM), a Dynamic Random-Access Memory (DRAM), or a Synchronous dynamic random-access memory (SDRAM). The non-volatile memory may be, for example, a Read-Only Memory (ROM), a Programmable Read-Only Memory (PROM), an Electronically Erasable Programmable Read-Only Memory (EEPROM), a Flash memory, an optical storage, or a magnetic storage. In general, memory may be referred to as a non-transitory computer-readable medium. The memory 1020 stores computer-readable instructions that are executed by the processor 1010. For example, a non-volatile memory stores computer-readable instructions, and the processor 1010 executes the instructions using a volatile memory for temporary storage of data and / or instructions.

[0107] The computer readable instructions may be pre-stored in memory 1020 or alternatively or additionally may be received by the device via an electromagnetic carrier signal and / or copied from a physical entity such as a computer program product. Execution of the computer readable instructions causes device 1000 to perform one or more of the functions described above.

[0108] In the context of this document, "memory" or "computer-readable medium" or "computer-readable media" may be any non-transitory medium or media or means capable of containing, storing, communicating, propagating, or carrying instructions for use by or in connection with an instruction execution system, apparatus, or device such as a computer.

[0109] The device 1000 may further comprise or be connected to an input unit 1030. The input unit 1030 may comprise one or more interfaces for receiving input. The one or more interfaces may comprise, for example, one or more temperature, motion and / or orientation sensors, one or more cameras, one or more accelerometers, one or more microphones, one or more buttons and / or one or more touch detection units. Furthermore, the input unit 1030 may comprise an interface to which an external device may be connected.

[0110] The device 1000 may also comprise an output unit 1040. The output unit may comprise or be connected to one or more displays capable of rendering visual content, such as a Light Emitting Diode (LED) display, a Liquid Crystal Display (LCD), and / or a Liquid Crystal on Silicon (LCoS) display. The output unit 1040 may further comprise one or more audio outputs. The one or more audio outputs may be, for example, speakers.

[0111] The device 1000 further comprises a connection unit 1050. The connection unit 1050 allows wireless connection to one or more external devices. The connection unit 1050 comprises at least one transmitter and at least one receiver, which may be integrated in the device 1000 or to which the device 1000 may be connected. The at least one transmitter comprises at least one transmitting antenna, and the at least one receiver comprises at least one receiving antenna. The connection unit 1050 may comprise an integrated circuit or a set of integrated circuits that provide the device 1000 with wireless communication capabilities. Alternatively, the wireless connection may be a hardwired application specific integrated circuit (ASIC). The connection unit 1050 may comprise one or more components, such as a power amplifier, a digital front end (DFE), an analog-to-digital converter (ADC), a digital-to-analog converter (DAC), a frequency converter, a (demodulation) modulator, and / or a code / decode circuit, controlled by a corresponding control unit.

[0112] It should be noted that the apparatus 1000 may further comprise various components not shown in Figure 10. The various components may be hardware components and / or software components.

[0113] As used in this application, the term "circuitry" may refer to one or more or all of the following: (a) Hardware-only circuit implementation (e.g., implementation in analog and / or digital circuits only) (b) A combination of hardware circuitry and software, such as (where applicable) (i) A combination of analog and / or digital hardware circuitry and software / firmware. (ii) Any portion of software (including digital signal processors), hardware processors having software and memory that work together to cause a device, such as a mobile phone, to perform various functions. (c) A hardware circuit and / or processor, such as a microprocessor or portion of a microprocessor, that requires software (e.g., firmware) to operate, but the software may not be present when it is not needed for operation.

[0114] This definition of circuitry applies to all uses of the term in this application, including any claims. As a further example, the term circuitry, as used in this application, also encompasses merely a hardware circuit or processor (or processors), or a portion of a hardware circuit or processor, as well as its (or their) accompanying software and / or firmware implementations. The term circuitry also encompasses, for example, a baseband or processor integrated circuit for a mobile device, or a similar integrated circuit in a server, cellular network device, or other computing or network device, if applicable to a particular claim element.

[0115] The techniques and methods described herein may be implemented by various means. For example, these techniques may be implemented in hardware (one or more devices), firmware (one or more devices), software (one or more modules), or a combination thereof. In the case of a hardware implementation, the apparatus of the exemplary embodiment may be implemented in 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), graphics processing units (GPUs), processors, controllers, microcontrollers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof. In the case of firmware or software, the implementation may be performed through modules (e.g., procedures, functions, etc.) of at least one chipset that performs the functions described herein. The software code may be stored in a memory unit and executed by the processor. The memory unit may be implemented within the processor or external to the processor. In the latter case, it may be communicatively coupled to the processor through various means, as known in the art. Additionally, the components of the systems described herein may be rearranged and / or supplemented with additional components to facilitate accomplishment of various aspects, etc., described in connection therewith, and are not limited to the precise configurations illustrated in the given figures, as will be understood by those skilled in the art.

[0116] It is obvious to those skilled in the art that as technology advances, the concept of the present invention can be implemented in various ways. The embodiment is not limited to the above exemplary embodiment, and can be modified within the scope of the claims. Therefore, all words and expressions should be interpreted broadly and are intended to describe the exemplary embodiment, not to limit it.

Claims

1. 1. An apparatus comprising at least one processor and at least one memory containing computer program code, the at least one memory and the computer program code being configured to execute, using the at least one processor: selecting a subset of radio resources from a set of candidate radio resources; determining a set of resource indexes for the subset of radio resources based at least in part on a predefined enumeration order of the set of candidate radio resources in time and frequency; determining a first resource indication value indicative of at least said set of resource indexes; transmitting the first resource indication to one or more second terminal devices; determining a second resource indication indicative of a plurality of resource sizes associated with the subset of radio resources; transmitting the second resource indication to the one or more second terminal devices; The apparatus is characterized in that it is included in a first terminal device.

2. 2. The apparatus of claim 1, wherein the first resource indication is determined by using a combinatorial number system.

3. 3. The apparatus of claim 1 or 2, wherein the first resource indication further indicates a resource size associated with the subset of radio resources.

4. 4. The apparatus according to claim 1, further comprising the step of transmitting a permutation index indicating a permutation of the subset of radio resources to the one or more second terminal devices.

5. 5. The apparatus of claim 1, wherein the set of resource indexes is determined by starting with the time.

6. 5. The apparatus of claim 1, wherein the set of resource indices is determined by starting with the frequency.

7. 1. An apparatus comprising at least one processor and at least one memory containing computer program code, the at least one memory and the computer program code being configured to execute, using the at least one processor: receiving a first resource indication and a second resource indication from a first terminal device, the first resource indication indicating at least a set of resource indexes associated with a subset of radio resources, a resource index within the set of resource indexes indicating a position of a radio resource included in the subset of radio resources in time and frequency, and the second resource indication indicating a plurality of resource sizes associated with the subset of radio resources; determining the subset of radio resources from a set of candidate radio resources based at least in part on the first and second resource indications; selecting a radio resource from the subset of radio resources for a sidelink transmission; The apparatus is characterized in that it is included in a second terminal.

8. The apparatus of claim 7, wherein the subset of radio resources is determined at least in part by determining the resource size based on the received second resource indication value.

9. 9. The apparatus of claim 7 or 8, wherein the subset of radio resources is determined at least in part by determining a set of logical slot offsets and a set of starting subchannel indexes associated with the subset of radio resources based at least in part on the set of resource indexes.

10. 10. The apparatus of claim 7, further comprising the step of transmitting the sidelink transmission using at least the selected radio resources.

11. selecting, by a first terminal device, a subset of radio resources from a set of candidate radio resources; determining, by the first terminal device, a set of resource indexes for the subset of radio resources based at least in part on a predefined enumeration order of the set of candidate radio resources in time and frequency; determining, by the first terminal device, a first resource indication value indicative of at least the set of resource indexes; transmitting, by the first terminal device, the first resource indication to one or more second terminal devices; determining a second resource indication indicative of a plurality of resource sizes associated with the subset of radio resources; and transmitting the second resource indication to the one or more second terminal devices.

12. receiving, by a second terminal device, a first resource indication and a second resource indication from the first terminal device, the first resource indication indicating at least a set of resource indexes associated with a subset of resources, a resource index within the set of resource indexes indicating a position of a radio resource included in the subset of radio resources in time and frequency, and the second resource indication indicating a plurality of resource sizes associated with the subset of radio resources; determining, by the second terminal device, the subset of resources from a set of candidate resources based at least in part on the first and second resource indication values; and selecting, by the second terminal device, resources from the subset of resources for sidelink transmission.

13. at least, selecting a subset of radio resources from a set of candidate radio resources; determining a set of resource indexes for the subset of radio resources based at least in part on a predefined enumeration order of the set of candidate radio resources in time and frequency; determining a first resource indication value indicative of at least said resource index; transmitting the first resource indication to one or more second terminal devices; determining a second resource indication indicative of a plurality of resource sizes associated with the subset of radio resources; and transmitting the second resource indication to the one or more second terminal devices, The apparatus is included in a first terminal.

14. at least, receiving a first resource indication and a second resource indication from a first terminal device, the first resource indication indicating at least a set of resource indexes associated with a subset of resources, a resource index within the set of resource indexes indicating a position of a radio resource included in the subset of radio resources in time and frequency, and the second resource indication indicating a plurality of resource sizes associated with the subset of radio resources; determining the subset of resources from a set of candidate resources based at least in part on the first and second resource indications; selecting resources from the subset of resources for sidelink transmission, The apparatus is included in a second terminal device.

15. A system comprising at least a first terminal device and a second terminal device, The first terminal device is selecting a subset of radio resources from the set of candidate radio resources; determining a set of resource indexes for the subset of radio resources based at least in part on a predefined enumeration order of the set of candidate radio resources in time and frequency; determining a first resource indication indicative of at least the set of resource indices; transmitting the first resource indication to the second terminal device; determining a second resource indication indicative of a plurality of resource sizes associated with the subset of radio resources; transmitting the second resource indication to the one or more second terminal devices; The second terminal device is receiving the first and second resource indications from the first terminal device; determining the subset of radio resources from the set of candidate radio resources based at least in part on the first and second resource indications; 22. A system for selecting radio resources from the subset of radio resources for sidelink transmission.

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