CN116368854A - Energy saving in sidelink communication - Google Patents

Abstract

In order to reduce the extra power consumption of the energy-saving user equipment caused by the preemption of transmission resources, the identifier of the transmitter or receiver of the energy-saving user equipment is included in the resource reserved message. When the user equipment tries to reserve resources, the user equipment may decide whether to preempt the reserved resources based on whether the reserved resources are power-saving user equipment.

Description

Energy saving in sidelink communication

technical field

The present disclosure relates to a periodic resource reservation in a cellular network, and in particular to a resource reservation scheme involving sidelink communications.

Background technique

Wireless communication systems such as third generation (3G) mobile telephony standards and technologies are well known. Such 3G standards and technologies are developed by the Third Generation Partnership Project (3GPP) (RTM). Third-generation wireless communications are typically used to support macrocellular mobile phone communications. Communication systems and networks have evolved towards broadband and mobile systems.

In a cellular radio communication system, a User Equipment (UE) is connected to a Radio Access Network (RAN) via a radio link. The RAN includes a set of base stations that provide radio links to UEs in cells covered by the base stations, and the RAN also provides an interface to the Core Network (CN) controlled by the overall network. It is worth noting that RAN and CN each perform their respective functions related to the overall network. For convenience, the term cellular network is used to refer to the combination of RAN and CN, it being understood that the term is used to refer to the corresponding systems for performing the disclosed functions.

The 3rd Generation Partnership Project developed the so-called Long Term Evolution (LTE) system for mobile access networks, the Evolved Universal Mobile Telecommunications System Regional Radio Access Network (E-UTRAN), in which one or more Or eNB (evolved NodeB) base station support. More recently, LTE is being further developed towards 5G or New Radio (NR) systems, where one or more cells are supported by base stations called gNBs. NR recommends using the Orthogonal Frequency Division Multiplexing (OFDM) physical transmission format.

The NR agreement is designed to provide the option to operate in the unlicensed radio frequency band known as NR-U. When operating in unlicensed radio bands, gNBs and UEs must compete with other devices for physical medium/resource access. For example, Wi-Fi (RTM), NR-U and LAA can use the same physical resources.

The trend in wireless communication is to provide lower latency and higher reliability services. For example, NR is designed to support Ultra-Reliable and Low-Latency Communications (URLLC), while Massive Machine Type Communications (mMTC) is designed to provide low latency and high reliability for small packets (typically 32 bytes in size), where the user plane The delay is 1ms, the reliability is 99.99999%, and the packet loss rate of the physical layer is 10 ^-5 or 10 ^-6 .

The mMTC service is designed to support a large number of devices over a long lifetime through an energy-efficient communication channel, where data transfers to and from each device occur sporadically and infrequently. For example, a unit may need to support thousands of devices.

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

Contents of the invention

This Abstract introduces the concepts of the disclosure in a simplified form that are further described below in the Detailed Description. This Abstract does not identify key features or essential features of the claimed subject matter of this disclosure, nor is it intended to be used to determine the scope of the claimed subject matter.

The present disclosure provides a method for selecting transmission resources in a cellular network, the method is performed by a user equipment UE, and the method includes the following steps: determining a potential set of available transmission resources, which are reserved for communication with an energy-saving UE according to a first criterion The transmitted transport resources are not considered as available transport resources; and selecting a transport resource from the set of available transport resources for use by the UE.

Wherein, the first criterion is to identify whether the sending UE or the receiving UE is an energy-saving UE on reserved resources.

Wherein, the energy-saving UE is identified by an indication in the first-stage SCI or the second-stage SCI.

Wherein, the indication includes flag bits.

Wherein, the indication includes identification IDs of part or all of the UEs.

Wherein, the first criterion is the priority of the reserved resources, wherein the priority will increase according to the reservation priority of the resources relative to the energy-saving UE.

Wherein, the potential set of available transmission resources is identified according to a comparison result of the received signal and a threshold.

Wherein, the first criterion is to compare the RSRP of the received signal with the threshold, wherein the threshold or the RSRP is adjusted according to the reservation related to the energy-saving UE.

The disclosure also provides a transmission resource selection method performed in a cellular network, the method is performed by a user equipment UE, and the method includes the following steps: determining a potential group of available transmission resources according to a comparison between a received signal and a threshold; repeating the The step of determining the set of potentially available transmission resources is based on a reduced threshold, and the reserved transmission resources between each iteration of determining and saving energy UEs is based on an original threshold, wherein the reduced threshold is smaller than the original threshold.

Wherein, when the priority is higher than the priority threshold, the threshold of reserved transmission resources used for transmission with the energy-saving UE is not adjusted.

The present disclosure further provides a data transmission method between user equipment UEs, the method comprising: sending a first-phase SCI message from the UE intending to transmit, wherein the first-phase SCI includes indicating whether the receiving UE or the sending UE of the transmission is for an energy-saving UE; and transmitting a second-phase SCI, and then transmitting data according to resources indicated by the second-phase SCI.

Wherein, the indication includes flag bits.

Wherein, the indication includes at least a partial ID of the receiving UE.

Wherein, the indication is sent by reusing existing fields in the SCI of the first stage, and the existing fields include frequency resource allocation or modulation and coding scheme fields.

Wherein, the indication includes a bit indicating whether the receiving UE is the energy-saving UE and a bit indicating whether the sending UE is the energy-saving UE.

The present disclosure also provides a user equipment configured to execute the foregoing method.

Description of drawings

Further details, aspects and embodiments of the invention will be described, by way of example only, with reference to the accompanying drawings. Components in the figures are for ease of illustration and have not necessarily been drawn to scale. For ease of understanding, the same components are given the same reference numerals in the various drawings.

Figures 1 and 2 show schematic diagrams of selected elements of a cellular communication network.

Detailed ways

Those skilled in the art will recognize and understand that the specific details of the described examples are merely illustrative of some embodiments, and that the teachings set forth herein are applicable to various alternative arrangements.

Figure 1 shows a schematic diagram of the three base stations (eg, eNB or gNB, depending on the particular cellular standard and terminology) that make up a cellular network. Typically, each base station is deployed by a cellular network operator to provide geographic coverage for UEs in that area. The base stations form a Radio Area Network (RAN). Each base station provides wireless network coverage for UEs in its area or cell. The base stations are interconnected through the X2 interface and connected to the core network through the S1 interface. In order to illustrate the key features of a cellular network, only essential details are drawn here. The PC5 interface is used for sidelink (SideLink, SL) communication between UEs. Interface and component names associated with Figure 1 are used as examples only, and different systems operating on the same principles may use different nomenclature.

Each base station contains the hardware and software to implement RAN functions, including communication with the core network and other base stations, control and data signaling between the core network and UEs, and maintaining wireless communication with the UEs associated with each base station. The core network includes the hardware and software that implement network functions, such as overall network management and control, and the routing of calls and data.

In addition to the uplink/downlink communication between the UE and the base station, sidelink communication in which UEs directly communicate with each other can also be implemented. Figure 2 shows a base station 102 forming a RAN, and a UE 150 with a sidelink transmitter (SL Tx UE) and a UE 152 with a sidelink receiver (SL Rx UE) in the RAN. UE 150 and UE 152, although depicted as transmitters and receivers, are for illustration only during a particular communication, and their roles could equally be reversed. Base station 102 is in wireless communication with SL Tx UE 150 and SL Rx UE 152 over respective connections 154 . Tx UE 150 and Rx UE 152 are configured to communicate wirelessly with each other via sidelink 156 .

The sidelink transmission is using traditional Uu transmission between the base station and UE, using TDD (half-duplex) to run on a dedicated carrier or a shared carrier. Utilize resource pools of transmission resources to manage resources and allocations, and to manage interference between potential concurrent transmissions. A resource pool is a group of time-frequency resources from which transmission resources can be selected. The UE can configure multiple transmission and reception resource pools.

There are two modes of operation for resource allocation for sidelink communications, depending on whether the UE is within the coverage of the cellular network or not. In Mode 1, V2X communication operates within the coverage of a base station (e.g. eNB or gNB). All scheduling and resource allocation can be done by the base station.

Mode 2 is applicable when the sidelink service is running outside the coverage of the cell site, at which point the UE needs to make its own arrangements. For fair utilization, UEs typically use sensing-based transmission resource allocation. Selecting resources consists of two steps. In step 1, the UE will identify resources that are considered available for selection, and in step 2, select specific resources for transmission. Step 1 may start by selecting a set of all resources in the window, and then delete those resources that are not considered candidate resources (eg resources reserved by another UE with SL-RSRP above a threshold). The step of selecting resources may be a random selection, possibly with constraints such as HARQ timing and delay between resources.

In mode 2, the UE selects transmission resources desired for transmission, and transmits a Sidelink Control Information (SCI) message indicating these resources. The receiver of the SCI message (which may be a single UE in unicast, a group of UEs in multicast, or all accessible UEs in broadcast) can learn the expected transmission details through the SCI.

Existing sidelink communication developments focus on "always on" devices for which power consumption is not a significant concern. The following disclosure addresses energy saving issues associated with using sidelink communications with UEs with limited power budgets, also so-called Power Saving User Equipment (PSUEs). In particular, this application emphasizes resource selection for UEs in Mode 2 operation and seeks to provide mechanisms to reduce redundant transmissions and protect resources for transmissions to and from PSUEs.

The embodiments listed below aim to reduce power consumption by improving transmission reliability, thereby reducing the number of repetitions required to achieve a given quality of service. This can be achieved by protecting resources used for transmissions to and from the PSUE to avoid collisions. In sidelink communications, the presence of a PSUE as a transmitter or receiver may be indicated to other UEs, for example in a message reserving transmission resources, such as a Sidelink Control Information (SCI) message.

An indication may be added to the Phase 1 SCI message that the message is for a PSUE. Therefore, the PSUE only needs to decode the second stage SCI message when there is such an indication, thereby reducing the power consumption of wasteful decoding. In addition, non-PSUEs may perform resource reselection when they detect conflicts with resources selected by PSUEs. This reduces collisions with PSUE transmissions, thereby improving the reliability of PSUE transmissions and potentially reducing the number of repetitions required. Furthermore, it is disclosed below that resource allocation can be performed without pre-emptive verification or re-evaluation prior to PSUE transmission. This may increase the probability of collisions, but combined with other techniques discussed in this paper for protecting PSUE resources aim to make PSUE transmissions more energy efficient.

The details of these different techniques are as follows.

A sidelink transmission may collide with another sidelink transmission from a different UE, or resources may be preempted by another UE, if the associated resource pool (RP) allows it. Due to collisions and/or preemption, the UE needs to perform additional (re)transmissions to achieve a certain target Quality of Service (QoS), these additional (re)transmissions increase the power consumption of the UE, which is a particular difficulty for PSUE .

To reduce the need for additional transmissions, preemption of transmission resources reserved by the PSUE may not be allowed.

When preparing to transmit, resources reserved for PSUE transmission may be deleted from the resource pool used to select resources to implement preemption of PSUE transmission resources. That is to say, regardless of the configuration of the resource pool, the relative priority or the RSRP threshold, the transmission resources reserved by the PSUE cannot be selected. Therefore, transmission resources reserved by the PSUE cannot be preempted and thus available for planned transmissions.

Preventing any preemption may provide a high level of protection for PSUE transmissions, which may be greater than an appropriate level for general network performance. This issue can be resolved using the following techniques. Autonomous resource selection for sidelink devices (mode 2 discussed above)2 works in 2 steps:

i. The first step aims to determine a set of resource groups considered available by deleting all resources related to the configured Reference Signal Received Power (RSRP) threshold. For this, two priorities are configured for the RSRP threshold, one for expected transmissions and one for detected/sensed transmissions. This step should provide at least X% of the resources, otherwise the RSRP threshold should be relaxed and this resource identification step repeated.

ii. The second step will mainly select resources in a random manner, but with some restrictions (for example, when multiple resources need to be selected, the feedback time or delay between multiple resources can be considered again).

By keeping resources available in the first step of resource identification, but freezing the RSRP threshold reserved by energy-efficient UEs when iterating the resource selection algorithm, limited preemption of resources reserved by PSUEs can be allowed. Therefore, even though resources can be preempted, they can only be held to a higher standard than other resources. Furthermore, RSRP thresholds for PSUE transmissions may not be adjusted if they have a higher priority than configured thresholds.

Therefore, the present disclosure provides a transmission resource selection method, in which a UE selects a resource to be transmitted from an available resource pool. In a first example, resources reserved by the PSUE are excluded from the pool of available resources. In a second example, when the RSRP threshold for selecting resources is iterated through the resource selection process, it is adjusted for resources reserved for non-PSUEs, but not for resources reserved for PSUEs. Also, the RSRP threshold is not adjusted when the priority of the transmission is higher than the configured threshold.

In order to prevent preemption, the UE must be able to recognize the indication of the subscription made by the PSUE. This indication may be provided in the SCI of the reserved resource. In a first example, the phase 1 SCI may carry the indication, for example using one or more reserved bits in the phase 1 SCI, or may carry the indication in the phase 2 SCI. Therefore, other UEs detecting SCI can recognize the resource as a PSUE reserved transmission resource and handle it appropriately during resource selection.

In addition to power consumption during transmission, power is also consumed during reception, since the UE must wake up to receive and decode the signal. If the expected transmission is not received, the power consumed while waking up is wasted, and further transmission opportunities must be utilized to send and receive data. If the second UE selects a resource that is scheduled to transmit to the PSUE, a collision may prevent the data from being successfully decoded, or if the original reservation is canceled, the PSUE will wake up and listen for the outstanding transmission. Further transfers are then required to complete the transfer successfully. All of these lead to increased power consumption of the PSUE.

To alleviate these problems, transmissions to PSUEs can be protected from selection or preemption. The above techniques for protecting transmissions to PSUEs are also applicable to transmissions to PSUEs. Resources can be removed from the pool of available resources, or the techniques described above can be used, such as freezing the RSRP threshold described above.

In order to identify a transmission to a PSUE for protection, an indication that the transmission is destined for the PSUE needs to be provided. This can be achieved as discussed above for PSUE transmissions, for example by including an indication of reserved resources in the SCI. The transmitting UE can know that the destination is a PSUE through various mechanisms. Before data transmission, higher layers exchange information that the UE is a PSUE during the configuration phase. For broadcast transmissions, transmissions to PSUEs may be marked if the transmitting UE knows from the message content that it is intended for one or more PSUEs.

Conventional sidelink transmission procedures use a two-phase SCI, where the first-phase SCI includes no indication of the source or destination of the intended transmission. Therefore, sidelink devices must monitor and decode Phase 1 SCI and Phase 2 SCI to be able to identify whether a planned transmission is appropriate. In the two phases of decoding SCI, the UE must receive the first phase SCI in the first 2 slot symbols and receive enough data (shared channel) DMRS signals to prepare for channel estimation, then receive and decode the second phase transmitted over the PSSCH Stage SCI. This requires a lot of time and power consumption to determine whether the transmission is intended for the UE, and wastes power if the transmission is not intended for the UE.

To address this shortcoming, the Phase 1 SCI may include an indication for transmission to the PSUE. If the Phase 1 SCI received and decoded by the PSUE does not indicate that the PSUE is the destination, the PSUE does not need to attempt to receive the Phase 2 SCI because the PSUE knows that the transmission is not suitable for it. Therefore, the PSUE can go back to sleep after decoding the first-stage SCI, thereby saving power consumption. If the indication in the first-stage SCI is determined to be a transmission for the PSUE, the PSUE may continue to receive the DMRS, and determine whether the transmission is applicable in the second-stage SCI.

The PSUE reception indication in the SCI at the first stage may be a yes/no indication, for example, the PSUE reception indication may be represented by a single bit, so as to minimize signaling overhead. While this is efficient for signaling overhead, it is still required that all PSUEs receiving the message continue to decode the second stage SCI. A finer granularity can be provided by indicating a portion of the ID of the receiving UE (e.g. the last x bits), such that UEs whose IDs do not match the indicated portion do not need to continue receiving and decoding the second stage SCI. Therefore, there is a trade-off between signaling overhead and the number of UEs unnecessarily decoding the second stage SCI.

The present disclosure provides a method of data transmission between UEs, comprising sending a first-stage SCI message from a UE intending to transmit, wherein the first-stage SCI includes an indication whether the receiving UE of the transmission is a PSUE. The indication can be a flag consisting of a single bit, or it can be part of the receiving UE ID. The indication may be decoded by a receiving UE receiving a first-stage SCI including an indication of whether the receiving UE is a PSUE. If the indication indicates that the receiving UE is a PSUE, and the UE is a PSUE, the UE may continue to receive and decode the second-stage SCI, otherwise, the UE may not continue to receive the second-stage SCI. Since the Phase 1 SCI contains information about reserved transmission resources, receiving only Phase 1 SCI still allows the UE to maintain the need for reserved transmission resources when planning its own transmissions. The indication in the first-stage SCI that the receiving UE is a PSUE can be used in conjunction with any of the above disclosures to protect resources reserved by the SCI.

In an example, one (or more) reserved bits in the first stage SCI may be used to contain the indication of PSUE reception, these reserved bits are configured by the higher layer (RRC) parameter "sl-NumReservedBits". Alternatively, one bit in an existing field can be re-used for this purpose, for example, a bit of "frequency resource allocation" or "modulation and coding scheme" can be used to indicate the PSUE as the receiving UE. For multicast and broadcast transmissions, a PSUE indication may be flagged (as are all aspects of the present disclosure) if at least one PSUE is part of the intended recipient UEs.

The phase one SCI may also (or instead) include an indication that the transmission originated from the PSUE, for use as described above. For this purpose, the first stage SCI may use two bits, one bit is used to indicate the transmitting UE as PSUE and the other bit is used to indicate the receiving UE as PSUE. In order to reduce signaling overhead, one bit may also be used to indicate whether one or both of the transmitting UE and the receiving UE are PSUEs. However, using a single bit for both possibilities does remove the advantage in preventing the PSUE from decoding the second stage SCI, since the UE cannot distinguish whether the transmitting UE or the receiving UE is a PSUE.

In conventional sidelink operation, if the reserved resource detected by the UE is one of several reserved resources and if the new reserved resource is due to another priority caused by a UE preempting a higher than preempting transmission, which will trigger a reselection of its own transmission. If the preempting UE is a PSUE under normal procedure, it will still perform reselection, incurring a power penalty due to the reselection process, or the transmission will cause a collision and may require a retransmission, which also incurs a power penalty .

To avoid the PSUE having to reselect resources and avoid collisions, if the UE detects conflicting reservations from the PSUE (for example, this might be detected during the re-evaluation phase of a sidelink transmission), it considers Its own reserved resources are preempted by PSUE. That is, the PSUE is granted priority access to transmission resources to avoid the PSUE having to reselect resources, thereby avoiding the power loss of this reselection process. Conversely, another UE (assumed not to be a PSUE), even if it could transmit in the legacy procedure and collides with the PSUE's transmission, will perform a reselection procedure to avoid collision with the PSUE. The same principle can be applied where the PSUE is the receiving UE's transmission. Therefore, power loss due to PSUE reselection and collision is avoided.

In another approach, PSUE transmissions may be prioritized to reduce the likelihood of resources being preempted, rather than completely preventing preempted or colliding transmissions with PSUE transmissions. This allows preemption in cases where priorities differ widely, meaning transmission collisions are non-trivial or time sensitive, but allow the PSUE to continue transmitting in most cases. The MAC or PHY layer may update the priority of transmissions to and/or from the PSUE.

The present disclosure discloses a sidelink transmission method, wherein before making a transmission, the UE checks for conflicting resource reservations, and if a conflicting reservation is detected for a transmission from and/or to the PSUE, the UE does not continue to transmit and reselects the transmission resource. Alternatively, the priority of PSUE transmissions may be increased due to the PSUE involved, and preemption may be allowed based on this modified priority.

In the traditional transmission process, if preemption is enabled for the resource pool before transmission, the MAC layer will request the PHY layer to verify whether the reserved resources are still available (that is, the reserved resources have not been preempted). However, this verification may consume a lot of power, which is undesirable for PSUE. Not performing this verification check can reduce power consumption, but it increases the number of collisions, which reduces overall system performance. Even without authentication checks, performance can be preserved by preventing preemption of resources reserved for transmissions to and/or from the PSUE. Therefore, non-PSUEs will reselect resources to avoid conflicts with PSUE reservations. Therefore, the power consumption and transmission time of non-PSUEs will suffer because they are forced to reselect resources, but this may not be a significant disadvantage.

To achieve compatibility between UEs that support and do not support PSUE protection, it may be more efficient to allocate resource pools based on available support. For example, one resource pool may be used for PSUEs and UEs that support protection, and another resource pool may be used for UEs that do not support protection PSUEs. This arrangement ensures that all UEs that may receive an indication of a PSUE-related transmission can decode the indication and take appropriate action.

Various methods have been disclosed in this application to protect PSUE transmission resources to improve PSUE power consumption related to sidelink transmissions.

Although not shown in detail, any device forming part of a network may include at least a processor, a memory unit and a communication interface configured to perform the method of any aspect of the invention. Further options and selections are described below.

Embodiments of the present invention, especially the signal processing functions of the gNB and the UE, can be implemented using computer systems or architectures known to those skilled in the relevant art. The computer system can be a desktop computer, laptop or notebook computer, handheld computing device (PDA, cell phone, PDA, etc.), server, client, or any other type that can use the general-purpose computing device. A computer system may include one or more processors, which may be implemented using general or special purpose processing engines, such as microprocessors, microcontrollers or other control modules.

The computer system may also include main memory, such as random access memory (RAM) or other dynamic memory, for storing information and instructions executable by the processor. The main memory may also be used for storing temporary variables or other intermediate information needed during execution of instructions by the processor. The computer system may also include a read-only memory (ROM) or other static storage device for storing static information and instructions for the processor.

The computer system can also include an information storage system, which can include a media drive and a removable storage interface. A media drive may include a drive or other mechanism for holding or supporting removable storage media such as a hard disk drive, floppy disk drive, tape drive, optical disk drive, compact disk (CD) or digital video drive (DVD) (RTM) to read or write input drives (including rewritable drives or rewritable drives), or other removable or fixed media drives. The storage media may include, for example, hard disks, floppy disks, magnetic tape, optical disks, CDs or DVDs, or other fixed or removable media that is read from and written to by a media drive. The storage media may include computer-readable storage media having specific computer software or data stored therein.

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 computer system. Such components may include, for example, removable storage units and interfaces, such as program cartridges and cartridge interfaces, removable storage (e.g., flash memory or other removable memory modules) and memory slots, and other removable storage units as well as allowing software and data Interface for transfer from a removable storage unit to a computer system.

The computer system may also include a communication interface. Such communication interfaces can be used to allow software and data to be transferred between the computer system and external devices. Examples of communications interfaces may include modems, network interfaces (such as Ethernet or other NIC cards), communications ports (such as Universal Serial Bus (USB) ports), PCMCIA slots and cards, and the like. Software and data transmitted via the communications interface are in the form of signals, which may be electronic, electromagnetic and optical or otherwise capable of being received by the communications interface medium.

In this document, the terms "computer program product", "computer readable medium", etc. may be used generally to refer to a tangible medium, such as a memory, storage device, or storage unit. These and other forms of computer-readable media may store one or more instructions for use by a processor comprising a computer system to cause the processor to perform specified operations. Such instructions are generally referred to as "computer program code" (which may be grouped in a computer program or other grouping). When executed, the computer system can perform the functions of the embodiments of the present invention. Note that code may directly cause the processor to perform a specified operation, be compiled to do so, and/or be combined with other software, hardware, and/or firmware elements (e.g., a library of functions to perform standard functions) to do so .

The non-transitory computer readable medium may include at least one of the following: a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a read-only memory, a programmable read-only memory, an erasable programmable read-only memory, an EPROM, an electronically programmable Erase Programmable ROM and Flash. In embodiments where the components are implemented using software, the software may be stored on a computer readable medium and loaded into a computer 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 component. It is further contemplated that, for example, a semiconductor manufacturer may employ the inventive concept in the design of a stand-alone device, such as a microcontroller for a digital signal processor (DSP), or an application-specific integrated circuit (ASIC) and/or any other subsystem element .

For clarity, the above description describes embodiments of the invention with reference to a single processing logic. However, the inventive concept can also be implemented by a plurality of different functional units and processors to provide signal processing functionality. Hence, references to specific functional units are only to be seen as references to suitable means for providing the described functionality rather than indicative of a strict logical or physical structure or organization.

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

Accordingly, the components and components 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 this invention has been described in connection with some embodiments, it is not intended to be limited to the specific forms set forth herein. Rather, the scope of the present invention is limited only by the appended claims. Additionally, 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 components or steps.

Furthermore, although individually listed, a plurality of means, components or method steps may be implemented by eg a single unit or processor. Additionally, 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 claim category does not imply a limitation to that category, but rather an indication that the feature is equally applicable to other claim categories, where appropriate.

Furthermore, the order of features in the claims do 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, references in the singular do not exclude the plural. Thus references to "a", "an", "first", "second" etc do not preclude a plurality.

Although this invention has been described in connection with some embodiments, it is not intended to be limited to the specific forms set forth herein. Rather, the scope of the present invention is limited only by the appended claims. Additionally, 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 terms "comprises" or "comprises" do not exclude the presence of other elements.

Claims (16)

1. A method of selecting transmission resources in a cellular network, the method being performed by a user equipment, UE, the method comprising the steps of:

determining a set of potential available transmission resources, wherein transmission resources reserved for transmission with the power saving UE according to the first criterion are not considered as available transmission resources; and

and selecting transmission resources from the available transmission resource groups for use by the UE.

2. The method of claim 1, wherein the first criterion is to identify whether the transmitting UE or the receiving UE is a power saving UE on reserved resources.

3. The method of claim 2, wherein the power saving UE is identified by an indication in a first stage SCI or a second stage SCI.

4. A method according to claim 3, wherein the indication comprises a flag bit.

5. The method of claim 3 or 4, wherein the indication comprises an identification ID of some or all of the UEs.

6. The method of claim 1, wherein the first criterion is a priority of the reserved resources, wherein the priority is increased according to a reserved priority of the resources relative to the power saving UE.

7. The method of claim 1, wherein the potential set of available transmission resources is identified based on a comparison of a received signal to a threshold.

8. The method of claim 1, wherein the first criterion is to compare a reference signal received power, RSRP, of the received signal to the threshold, wherein the threshold or RSRP is adjusted in accordance with a reservation associated with the power saving UE.

9. A transmission resource selection method performed in a cellular network, the method being performed by a user equipment, UE, the method comprising the steps of:

determining a potential set of available transmission resources based on a comparison of the received signal to a threshold; and

the step of repeating the determining the set of potentially available transmission resources is based on a reduced threshold, the transmission resources reserved between each repeated determination and the power saving UE being based on an original threshold, wherein the reduced threshold is smaller than the original threshold.

10. The method of claim 9, wherein the threshold of reserved transmission resources for transmission with the power saving UE is not adjusted when the priority is higher than a priority threshold.

11. A method of data transmission between user equipments, UEs, the method comprising:

transmitting a first stage SCI message from a UE intended for transmission, wherein the first stage SCI comprises information indicating whether a receiving UE or a transmitting UE of a transmission is a power saving UE; and

and transmitting a second stage SCI, and then transmitting data according to the resources indicated by the second stage SCI.

12. The method of claim 11, wherein the indication comprises a flag bit.

13. The method according to claim 11 or 12, wherein the indication comprises at least part of the ID of the receiving UE.

14. The method according to any of the claims 11-13, characterized in that the indication is sent by reusing an existing field in the first stage SCI, said existing field comprising a frequency resource allocation or modulation coding scheme field.

15. The method according to any of claims 11 to 13, wherein the indication comprises a bit indicating whether the receiving UE is the power saving UE and a bit indicating whether the transmitting UE is the power saving UE.

16. A user equipment configured to perform the method of any of claims 1 to 15.

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