CN116326012A - Side chain resource selection - Google Patents

Abstract

A method of selecting resources for transmission is disclosed. The method comprises the following steps: a threshold set of received reference signal received powers, the threshold set comprising a reference signal received power threshold corresponding to each possible combination of a transmission priority value and a reservation priority value; detecting a set of resources within a resource selection window for transmission, wherein each resource in the set of resources is associated with a value of reference signal received power; receiving a priority value of the transmission; identifying a first subset of resources from the set of resources, wherein the first subset of resources comprises resources selectable for the transmission based on the set of thresholds and the priority value of the transmission; determining a ratio of the number of resources in the first subset of resources relative to the number of resources in the set of resources; and if the ratio of the number of resources in the first subset of resources to the number of resources in the set of resources is greater than or equal to a predetermined ratio, selecting at least one resource in the first subset of resources for the transmission.

Description

Side chain resource selection

Technical Field

The present invention relates to side chain resource selection, in particular for avoiding transmission collisions.

Background

Wireless communication systems, such as third-generation (3G) mobile phone standards and technologies, are well known. Such 3G standards and techniques have been developed by the third generation partnership project (Third Generation Partnership Project,3 GPP) (RTM). Third generation wireless communications have been developed in general to support macrocell mobile telephone communications. Communication systems and networks have evolved to broadband and mobile systems.

In a cellular wireless communication system, a User Equipment (UE) is connected to a radio access network (Radio Access Network, RAN) by a wireless link. The RAN includes a set of base stations that provide radio links to UEs in a cell covered by the base stations and an interface to a Core Network (CN) that provides overall Network control. It should be appreciated that the RAN and CN each perform a respective function related to the overall network. For convenience, the term cellular network will be used to refer to the combined RAN & CN, and it should be understood that the term is used to refer to the corresponding system for performing the disclosed functions.

The third generation partnership project has developed a so-called long term evolution (Long Term Evolution, LTE) system, i.e. an evolved universal mobile telecommunications system terrestrial radio access network (Evolved Universal Mobile Telecommunication System Territorial Radio Access Network, E-UTRAN) for mobile access networks in which one or more macro cells are supported by base stations called enodebs or enbs (evolved nodebs). Recently, LTE is further evolving towards so-called 5G or NR (new radio) systems, where one or more cells are supported by a base station called a gNB. NR is proposed to use an orthogonal frequency division multiplexing (Orthogonal Frequency Division Multiplexed, OFDM) physical transport format.

The NR protocol is intended to provide the option of operating in the unlicensed radio frequency range (referred to as NR-U). While operating in the unlicensed radio band, the gNB and UE must compete with other devices for physical media/resource access. For example, wi-Fi (RTM), NR-U, and LAA may use the same physical resources.

The trend in wireless communication is to provide lower latency and higher reliability services. For example, NR is intended to support Ultra-reliable and low-latency communication (URLLC), while large-scale Machine-type communication (Machine-Type Communications, mMTC) is intended to provide low latency and high reliability for small packet sizes (typically 32 bytes). The user plane delay of 1ms is proposed, the reliability is 99.99999%, and 10 is proposed in the physical layer ^-5 Or 10 ^-6 Packet loss rate of (a).

The mctc service aims to support a large number of devices over a long life-cycle through an energy efficient communication channel, where data transmission with each device is sporadic and infrequent. For example, one cell may need to support thousands of devices.

The following invention relates to various improvements to cellular wireless communication systems.

Drawings

Further details, aspects and embodiments of the invention will be described, by way of example only, with reference to the accompanying drawings. The components in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. Like reference numerals have been included in the corresponding drawings for ease of understanding.

Fig. 1 illustrates selected components of a cellular wireless communication network;

fig. 2 illustrates selected components in a radio area network of the cellular wireless communication network of fig. 1;

FIG. 3 illustrates a resource selection method;

FIG. 4 shows a resource table;

FIGS. 5A and 5B illustrate a table of available resources from FIG. 4 using the method of FIG. 3;

FIG. 6 illustrates a resource selection method;

FIG. 7 illustrates a resource table excluded from FIG. 4 using the method of FIG. 6;

FIG. 8 illustrates a table of available resources from FIG. 4 using the method of FIG. 6;

FIG. 9 illustrates a resource selection method;

FIG. 10 illustrates a table of available resources from FIG. 4 using the method of FIG. 9;

FIG. 11 illustrates a resource selection method; and

fig. 12 shows the available resources table from fig. 4 using the method of fig. 11.

Detailed Description

Those skilled in the art will recognize and appreciate that the specifics of the examples described are merely illustrative of some embodiments and that the teachings set forth herein are applicable in a variety of alternative settings.

Fig. 1 shows a schematic diagram of three base stations 102 (e.g., enbs or gnbs depending on the particular cellular standard and terminology) forming a cellular network. Typically, each base station 102 will be deployed by one cellular network operator to provide geographic coverage for UEs in the area. The base stations form a radio area network (Radio Area Network, RAN). Each base station 102 provides wireless coverage for UEs in its area or cell. The base stations 102 are interconnected by an X2 interface and connected to the core network by an S1 interface. It should be understood that only basic details are shown for the purpose of illustrating key features of a cellular network. A PC5 interface is provided between UEs for side-chain (SL) communication. The interface and component names associated with fig. 1 are for example only, and different systems operate on the same principles, possibly using different nomenclature.

Each base station 102 contains hardware and software for implementing RAN functions, including communication with the core network 104 and other base stations 102, control and data signaling between the core network and UEs, and UEs associated with each base station remain in wireless communication. The core network 104 includes hardware and software that implements network functions such as overall network management and control, and routing of calls and data.

In vehicle-to-vehicle (V2V) applications, the UE may be incorporated into vehicles such as automobiles, trucks, and buses. These in-vehicle UEs are able to communicate with each other in an in-coverage mode, where the base stations manage and allocate resources, and in an out-of-coverage mode, without any base stations managing and allocating resources. In a vehicle-to-evaluation (V2X) application, a vehicle may communicate not only with other vehicles, but also with infrastructure, pedestrians, cellular networks, and potentially other surrounding devices. The V2X use case includes:

the vehicles are queued, which enables the vehicles to dynamically form rows that travel together. All vehicles in a row acquire information from the leading vehicle to manage the row. This information allows the vehicle to travel in the same direction and together in a coordinated manner, closer than would normally be the case.

The extension sensor enables the exchange of raw or processed data collected by local sensors or real-time video images between vehicles, road site units, pedestrian devices and V2X application servers. The vehicle can increase the perception of the environment, so that the vehicle is beyond the detection range of the sensor, and the vehicle has wider and more comprehensive knowledge of the local situation. High data rates are one of the key characteristics.

Advanced driving, which may enable semi-automatic or fully automatic driving. Each vehicle and/or RSU shares its own sensory data obtained from its local sensors with nearby vehicles and allows the vehicles to synchronize and coordinate their trajectories or operations. Each vehicle also shares its driving intent with nearby vehicles.

Remote driving, which enables a remote driver or V2X application to operate a remote vehicle for passengers who cannot drive themselves or for remote vehicles located in a dangerous environment. For situations where the variation is limited and the route is predictable, such as public transportation, cloud computing based driving may be used. High reliability and low delay are major requirements.

Fig. 2 shows a base station 102 forming a RAN, and a transmitting (Tx) UE 150 and a receiving (Rx) UE 152 in the RAN. The base station 102 is arranged to communicate wirelessly with each of the Tx UE 150 and the Rx UE 152 via a respective connection 154. The Tx UE 150 and the Rx UE 152 are arranged to communicate wirelessly with each other via a side chain 156.

Side-chain transmission uses TDD (half duplex) on dedicated or shared carriers, and conventional Uu transmission is used between the base station and the UE. The resource pool of transmission resources is used to manage resource allocation and to manage interference between potentially concurrent transmissions. The resource pool is a set of time-frequency resources from which resources for transmission can be selected. The UE may configure multiple transmit and receive resource pools.

Two modes of operation are used for resource allocation for side-chain communications, depending on whether the UE is within the coverage of the cellular network. In mode 1, V2X communications are operating within the coverage of a base station (e.g., eNB or gNB). All scheduling and resource allocation may be performed by the base station.

Mode 2 applies when the V2X service is operating outside the coverage of the cellular base station. Here the UE needs to schedule itself. For fair utilization, UEs typically employ a perceptually based resource allocation. In mode 2, the UE reserves resources for transmission by sending a side chain control information (Sidelink Control Information, SCI) message indicating the resources to be used. The SCI informs the recipient (possibly a single UE in unicast, a group of UEs in multicast, or all reachable UEs in broadcast) of the details of the transmission it can expect. The UE may reserve transmission resources for the first transmission of a Transport Block (TB) for data, or may reserve transmission resources for repetition of the transmission TB to improve reliability in case of initial transmission failure.

Fig. 3 illustrates a method 300 of resource selection in mode 2 performed by a UE. In step 302, a processor of the ue receives an initial reference signal received power (Reference Signal Received Power, RSRP) threshold. These thresholds are configured for each pair of priority values, one of which is the priority of the own transmission for which the UE is performing resource selection, and the other of which is the priority of the detected data packet. In step 304, the processor of the ue receives the priority p_tx of the intended transmission. In step 306, the processor of the ue receives a value X of the percentage of the identified resources. The value of X may be a percentage between 0 and 100, preferably 20, 35 or 50.

In step 308, the ue detects resources within a resource selection window for the intended transmission. The resource selection window includes future resources on which the UE may select appropriate resources for transmission. This includes the UE receiving a priority value p_rx to detect reservations and an RSRP value in dB. The RSRP value is the estimated RSRP value p_rx of the received reservation and is the priority of the detected transmission/reservation, as shown in the side chain control information. In step 310, the processor of the ue identifies which of the resources detected from step 308 are selectable based on the RSRP threshold and the value of P tx. The identifying of step 310 may include the processor of the UE comparing the RSRP of the detected reservation with a threshold to identify the resource as a candidate or not. All resources that have received an RSRP that is greater than the RSRP threshold of the associated priority pair may be removed from the candidate list. In step 312, the processor of the ue determines a ratio of the optional resources relative to the number of detected resources from step 308. If the proportion of the alternative resources identified at step 312 is greater than or equal to X, then the method 300 proceeds to step 314. In step 314, the processor of the ue selects resources to use from the alternative resources identified in step 312. The resource selection at step 314 may be a random selection from the identified alternative resources. Under certain constraints, such as when multiple resources need to be selected, the hybrid automatic repeat request (Hybrid automatic repeat request, HARQ) feeds back timing or delay between the resources.

If, after step 312, the alternative resource proportion identified at step 312 is less than X, then the method 300 proceeds to step 316. In step 316, the processor of the ue increases the RSRP threshold. The increase in RSRP threshold may be 3dB. In some cases, the increase in RSRP threshold may be achieved by a fixed configuration offset value applied to all thresholds of the priority pair. The method 300 then returns to step 310, where the processor of the UE identifies which of the resources detected from step 308 are selectable based on the (increased) RSRP threshold and the value of P tx.

The RSRP threshold may be increased at step 316, which may mean that the resources for the transmission detected at step 308 with a higher priority than the UE's expected transmission priority P tx become part of the available candidate resources. Since resources may be randomly selected from the identified resources at step 314, this may result in selecting resources for transmission with the UE, which would conflict with the reserved resources of the detected high priority transmission.

Furthermore, if the UE detects a reservation of its reserved resources, the UE may trigger a repartition of its selected resources if the new reservation is for high priority transmission. On the other hand, if the previously reserved resources have a higher priority, the UE making the previously reserved may not trigger a resource reselection. Thus, high priority transmissions may result in a collision risk that the reliability objectives of the transmissions are not met.

Fig. 4 illustrates an example in which the UE detects (i.e., at step 308) twenty resources, each having a priority value p_rx of the detected reservation and an RSRP value in dB. The table may be considered as the resources contained in the resource selection window. The horizontal axis may represent the time dimension and the vertical axis may represent the frequency dimension (in the form of subchannels or other suitable granularity). In this example, only three priority values of Point-to-Point Protocol (PPP) are used: 0. 1 and 2, wherein a lower value indicates a higher priority. Table 1 provides an example initial threshold configuration for resource selection in mode 2:

TABLE 1

Using the configuration of table 1 and taking p_tx=1 and x=20% (i.e., steps 302 to 306), it can be seen that three of the detection resources of fig. 4 are alternative (i.e., step 310). The available resources for this case are shown in fig. 5A. The UE determines in step 312 that 3/20=15% of the resources are available. This is below the 20% configuration value of X and therefore the condition of X is not reached in the first iteration using the threshold configuration in table 1. Thus, the threshold is iteratively increased by 3dB until X is reached (i.e., step 316). Table 2 provides an example threshold configuration for resource selection, iterating twice from the initial configuration of table 1, increasing 3dB for each iteration. The reader will note that the threshold of the second column is updated by 6dB (2 iterations of 3 dB) for the priority p_tx=1 of the intended transmission.

TABLE 2

Using the configuration of table 2 and keeping p_tx=1 and x=20, it can be seen that six detection resources in fig. 3 are optional. The available resources in this case are shown in fig. 5B. The UE determines in step 312 that 6/20=30% of the resources are available. This is higher than 20%, so that X is implemented using the configuration of table 2. The UE may then select from the six available resources (i.e., step 314). However, the resource with higher priority, i.e., p_rx=0, is already available, and thus there is a risk of collision with the transmission with higher priority.

The following discusses methods related to avoiding conflicts in mode 2 resource selection.

Fig. 6 illustrates a resource selection method 600 in mode 2 performed by a UE. Method 600 is substantially the same as method 300. Method 600 includes step 602 between steps 308 and 310. In step 602, the processor of the ue excludes from the selection any resource p_rx in the detected resource set from the priority detection SCI that is higher than the offset of the expected transmission priority p_tx. The offset is an integer value, such as 1, 2 or 3. The offset may be 0, which will exclude resources with the same priority. Thus, when the UE selects resources for side-chain transmission with a given priority p_tx, subtracting the offset (as a lower value, meaning a higher priority) at a priority p_rx higher than p_tx is excluded from the resource selection window.

This avoids resource allocation that would result in a collision with a high priority transmission, since the UE cannot select in step 314 resources from the detected set of resources that have a priority p_rx higher than the priority p_tx of the intended transmission.

Returning to the example of detecting resources where p_tx remains 1 in fig. 4, fig. 7 shows the resources excluded in this case, i.e., p_rx=0. In this case, all resources in the selection window that have a higher priority than the intended transmission are excluded. This is achieved by an offset value of 1. After excluding the reserved resources of higher priority, the resources of higher priority are not available even after increasing 3dB by the RSRP threshold. The threshold is iteratively increased by 3dB until X is reached (i.e., step 316). Table 3 provides an example threshold configuration for resource selection iterating four 3dB from the initial configuration of table 1:

TABLE 3 Table 3

Using the configuration of table 3 and keeping p_tx=1 and x=20, it can be seen that 11 detection resources in fig. 3 are optional. The available resources in this case are shown in fig. 8. The UE determines that 55% of the resources are available at step 312. This is higher than 20%, so that X is implemented using the configuration of table 3. The UE may then select from the available resources (i.e., step 314). These may overlap with existing reservations. However, if needed by the UE that has performed the reservation, a preemption mechanism may be triggered. In this example, the "low RSRP-high priority" reservation is also excluded, which provides for safer transmission for high priority transmissions.

Fig. 9 illustrates a method 900 of resource selection in mode 2 performed by a UE. Method 900 is substantially the same as method 300. Method 900 includes a step 902 that may be performed between step 302 and step 310. In step 902, the processor of the ue sets the RSRP threshold of all pairs with p_rx having a higher priority than p_tx to a very low value, e.g., minus infinity. The resource pool may be configured with a "collision avoidance" flag. The UE performing the resource selection or reselection may perform step 902 when collision avoidance is activated by indicating an appropriate value of the flag as part of the resource pool configuration.

This avoids resource allocation that results in a collision with high priority transmissions, since the UE does not identify (at step 310) from the detected set of resources p_tx, resources with priority p_rx higher than the intended transmission priority.

Returning to the example of detecting resources with p_tx kept at 1 in fig. 4, table 4 provides an example threshold configuration for resource selection where the RSRP threshold for all pairs with p_rx having a higher priority than p_tx has been set to minus infinity and iterated four 3dB from the initial configuration of table 1. The table updates the RSRP threshold of all p_tx, p_rx pairs, where p_rx has a higher priority (lower value). In resource selection, since the UE will only use the RSRP threshold with p_tx equal to the expected transmission priority, only the correlation threshold associated with that P tx can be updated. For the example of ptx=1, it means that only the column associated with p_tx=1 is updated.

TABLE 4 Table 4

Using the configuration of table 4 and keeping p_tx=1 and x=20, it can be seen that 11 detection resources in fig. 3 are optional. The available resources in this case are shown in fig. 10. The UE determines that 55% of the resources are available at step 312. This is higher than 20%, so that X is implemented using the configuration of table 4. The UE may then select from the available resources (i.e., step 314).

Fig. 11 illustrates a method 1100 of resource selection in mode 2 performed by a UE. Method 1100 is substantially the same as method 300. Method 1100 replaces step 316 of method 300 with steps 1102 and 1104, which are performed if there are not enough resources available after step 312. In step 1102, the ue's processor freezes, i.e., locks or repairs, any RSRP threshold pairs, the detected priority p_rx being higher than the offset of p_tx. The offset is an integer value, such as 1, 2 or 3. This offset may be used with a value of 0, resulting in freezing a threshold with the same p_rx priority as p_tx. In step 1104, the ue's processor increases the RSRP threshold unless they are frozen. The increase in RSRP threshold may be 3dB, similar to step 316.

This resource selection approach avoids deleterious collisions with resources reserved for higher priority transmissions. In particular, although the method 1100 may result in the ultimately selected resources potentially conflicting with higher priority reservations, the conflicts may not be detrimental in that they may only occur with the constraint that the estimated RSRP of the detected higher priority reservations is below the initial configuration RSRP threshold, although the resource identification step may have multiple iterations, freezing the RSRP threshold associated with the higher priority does not allow for inclusion of reserved resources having a higher priority that are part of the identified resources for which the RSRP is greater than the initial configuration RSRP threshold. In other words, the "low RSRP-high priority" reservation remains available because it passes the initial criteria. But other high priority subscriptions will not be further considered and protected as they are not available for selection. This allows for greater flexibility in setting acceptable thresholds for spatial reuse of resources and enables high priority in a safer way.

Returning to the example of detecting resources of fig. 4, where p_tx remains at 1, table 5 provides an example threshold configuration for resource selection where the RSRP threshold of { p_tx=1, p_rx=0 } has been frozen at its initial value (as per table 1), while the other RSRP values iterate four times at 3dB from the initial configuration of table 1:

TABLE 5

Using the configuration of table 5 and keeping p_tx=1 and x=20, it can be seen that after 4 iterations, the 12 detection resources in fig. 3 are available for selection. The available resources in this case are shown in fig. 12. The UE determines that 60% of the resources are available at step 312. This is higher than 20%, so that X is implemented using the configuration of table 5. The UE may then select from the available resources (i.e., step 314). In the above described methods 600, 900, 1100, resource collision is avoided based on the priority p_tx of the transmission for which the UE is performing resource allocation. In an alternative scenario, the resource pool configuration may include a field indicating a critical priority p_p. The priority indicates a priority point beyond which all transmissions need to be protected. A UE performing resource allocation using method 600 will then exclude all resources whose detected priority is equal to or higher than the indicated critical priority p_p. The UE performing method 900 will set a low RSRP threshold for all pairs where p_rx has a priority equal to or higher than p_p. The UE performing method 1100 will freeze the RSRP threshold in step 1102 for all priority pairs where p_rx has a priority equal to or higher than p_p. The resource selection method discussed above has been described in which the prioritization is always performed with respect to the priority of the Tx UE p_tx performing the resource selection.

In this alternative approach, the set of priorities indicated by p_p is always protected by the method described previously, independently of p_tx. This ensures that transmissions with priority equal to or higher than the critical priority are transmitted. Thus, the UE performing resource allocation in the resource pool excludes resources or freezes the RSRP threshold to obtain a priority higher than the critical priority. This approach is particularly useful for high priority applications with URLLC constraints.

Although not shown in detail, any device or apparatus that forms part of the network may include at least a processor, memory, and a communication interface, wherein the processor, memory, and communication interface are configured to perform the following methods: any aspect of the invention. Further options and selections are described below.

The signal processing functions of embodiments of the present invention, particularly the gNB and the UE, may be implemented using computing systems or architectures known to those skilled in the relevant art. Computing systems, such as desktop, laptop or notebook computers, hand-held computing devices (PDAs, cell phones, palmtops, etc.), mainframes, servers, clients, or any other type of special or general purpose computing device may be desirable or appropriate for a given application or environment. A computing system may include one or more processors, which may be implemented using a general-purpose or special-purpose processing engine, such as a microprocessor, microcontroller, or other control module.

The computing system may also include a main memory, such as Random Access Memory (RAM) or other dynamic memory, for storing information and instructions to be executed by the processor. Such main memory may also be used for storing temporary variables or other intermediate information during execution of instructions to be executed by the processor. The computing system may also include a Read Only Memory (ROM) or other static storage device for storing static information and instructions for the processor.

The computing system may also include an information storage system, which may include, for example, a media drive and a removable storage interface. The media drive may include a drive or other mechanism to support fixed or removable storage media, such as a hard disk drive, floppy disk drive, magnetic tape drive, optical disk drive, compact Disk (CD) or Digital Video Drive (DVD) (RTM) read or write drive (R or RW), or other removable or fixed media drive. Storage media may include, for example, hard disk, floppy disk, magnetic tape, optical disk, CD or DVD, or other fixed or removable medium that is read by and written to by a media drive. The storage medium may include a computer-readable storage medium having stored therein specific computer software or data.

In alternative embodiments, the information storage system may include other similar components for allowing computer programs or other instructions or data to be loaded into the computing system. Such components may include, for example, removable storage units and interfaces such as program cartridge and cartridge interfaces, removable memory (e.g., flash memory or other removable memory modules) and memory slots, and other removable storage units and interfaces that allow software and data to be transferred from the removable storage units to the computing system.

The computing system may also include a communication interface. Such a communication interface may be used to allow software and data to be transferred between the computing system and external devices. Examples of communication interfaces may include modems, network interfaces (e.g., ethernet or other NIC cards), communication ports (e.g., universal Serial Bus (USB) ports), PCMCIA slots and cards, etc. Software and data transferred via the communications interface are in the form of signals which may be electronic, electromagnetic and optical or other signals capable of being received by the communications interface medium.

In this document, the terms "computer program product," "computer-readable medium," and the like may be used to generally refer to tangible media, such as memory, storage devices, or storage units. These and other forms of computer-readable media may store one or more instructions for use by a processor constituting a computer system to cause the processor to perform specified operations. Such instructions, generally 45, are referred to as "computer program code" (which may be grouped in the form of computer programs or other groupings), when executed, enable the computing system to perform functions of embodiments of the present invention. Note that the code may directly cause the processor to perform the specified operation, be compiled to do so, and/or be combined with other software, hardware, and/or firmware components (e.g., libraries for performing standard functions) to do so.

The non-transitory computer readable medium may include at least one from the group consisting of: hard disks, CD-ROMs, optical storage devices, magnetic storage devices, read-only memory, programmable read-only memory, erasable programmable read-only memory, EPROM, electrically erasable programmable read-only memory, and flash memory. In embodiments where the components are implemented using software, the software may be stored in a computer readable medium and loaded into a computing system using, for example, a removable storage drive. The control module (in this example, software instructions or executable computer program code) when executed by a processor in a computer system causes the processor to perform the functions of the invention as described herein.

Furthermore, the inventive concept may be applied to any circuit for performing signal processing functions within a network element. It is further contemplated that, for example, a semiconductor manufacturer may employ the concepts of the invention in the design of a stand-alone device, such as a microcontroller of a Digital Signal Processor (DSP), or an Application Specific Integrated Circuit (ASIC), and/or any other subsystem component.

It should be appreciated that for clarity, the above description has described embodiments of the invention with reference to a single processing logic. However, the inventive concept may equally be implemented by a number of different functional units and processors to provide a signal processing function, and thus references to specific functional units are only to be seen as references to suitable means for providing the described function, rather than indicative of a strict logical or physical structure or organization.

Aspects of the invention may be implemented in any suitable form including hardware, software, firmware or any combination of these. The invention may optionally be implemented at least partly as computer software running on one or more data processors and/or digital signal processors or configurable module components such as FPGA devices.

Thus, the components and elements of an embodiment of the invention may be physically, functionally and logically implemented in any suitable way. Indeed the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the invention is limited only by the appended claims. Furthermore, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term "comprising" does not exclude the presence of other elements or steps.

Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented by e.g. a single unit or processor. Furthermore, although individual features may be included in different claims, these may possibly be advantageously combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. Furthermore, the inclusion of a feature in one category of claims does not imply a limitation to this category but rather indicates that the feature is equally applicable to other claim categories as appropriate.

Furthermore, the order of features in the claims does not imply any specific order in which the features must be performed, and in particular the order of individual steps in a method claim does not imply that the steps must be performed in this order. Rather, the steps may be performed in any suitable order. Furthermore, singular references do not exclude a plurality. Thus, references to "a", "an", "first", "second", etc. do not exclude a plurality.

Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the invention is limited only by the appended claims. Furthermore, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term "comprising" or "comprises" does not exclude the presence of other elements.

Claims (14)

1. A method of selecting resources for transmission, comprising:

a threshold set of received reference signal received powers, the threshold set comprising a reference signal received power threshold corresponding to each possible combination of a transmission priority value and a reservation priority value;

detecting a set of resources within a resource selection window for transmission, wherein each resource in the set of resources is associated with a value of reference signal received power;

receiving a priority value of the transmission;

identifying a first subset of resources from the set of resources, wherein the first subset of resources comprises resources selectable for the transmission based on the set of thresholds and the priority value of the transmission;

determining a ratio of the number of resources in the first subset of resources relative to the number of resources in the set of resources; and

at least one resource in the first subset of resources is selected for the transmission if the ratio of the number of resources in the first subset of resources to the number of resources in the set of resources is greater than or equal to a predetermined ratio.

2. The method of claim 1, comprising receiving the predetermined ratio.

3. A method according to any preceding claim, comprising: if the ratio of the number of resources in the first subset of resources to the number of resources in the set of resources is less than the predetermined ratio:

increasing each threshold in the set of thresholds;

identifying a second subset of resources, wherein the second subset of resources comprises resources in the set of resources selectable for the transmission based on the increased threshold value and the priority value of the transmission;

determining a ratio of the number of resources in the second subset of resources relative to the number of resources in the set of resources; and

at least one resource in the second subset of resources is selected for the transmission if the ratio of the number of resources in the second subset of resources to the number of resources in the set of resources is greater than or equal to the predetermined ratio.

4. The method of claim 3, wherein increasing each threshold in the set of thresholds comprises increasing each threshold by 3dB.

5. The method according to any of claims 1 to 4, wherein each resource in the set of resources is associated with the reservation priority value, the method comprising:

any resources having the reservation priority value greater than a predetermined offset above the priority value of the transmission are excluded from the set of resources prior to identifying the first subset of resources.

6. The method according to any one of claims 1 to 4, comprising:

the threshold is set to a low value for each combination of the priority value of the transmission and the reservation priority value in the set of thresholds for which the reservation priority value is higher than the priority value of the transmission before the first subset of resources is identified.

7. The method of claim 6, wherein the low value is minus infinity.

8. The method according to claim 1 or 2, comprising: if the ratio of the number of resources in the first subset of resources to the number of resources in the set of resources is less than the predetermined ratio:

freezing the threshold value of each combination of the priority value and a reserve priority value of the transmission in the set of thresholds, wherein the reserve priority value is greater than a predetermined offset above the priority value of the transmission; and

each threshold in the set of thresholds is increased unless the threshold is frozen.

9. The method of claim 8, wherein increasing each threshold in the set of thresholds comprises increasing the threshold by 3dB unless the threshold is frozen.

10. A method according to claim 5, 8 or 9, wherein the predetermined offset is an integer value.

11. The method of claim 10, wherein the predetermined offset is 0, 1, 2, or 3.

12. The method of any preceding claim, wherein the steps are performed at or by a UE.

13. A UE, comprising: a processor arranged to perform the method of any one of claims 1 to 12.

The wake-up signal is configured by the base station before the next paging occasion PO, where PEI indicates information of the UE group/subgroup for paging before the next PO.

14. A non-transitory computer readable medium storing instructions which, when executed by a computer, perform the method of any one of claims 1 to 12.

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