WO2022073481A1

WO2022073481A1 - Power saving for sidelink communications

Info

Publication number: WO2022073481A1
Application number: PCT/CN2021/122685
Authority: WO
Inventors: Umer Salim; Virgile Garcia
Original assignee: Huizhou Tcl Cloud Internet Corporation Technology Co., Ltd.
Priority date: 2020-10-09
Filing date: 2021-10-08
Publication date: 2022-04-14
Also published as: CN116368854A

Abstract

In order to reduce power consumption of power saving UEs due to pre-emption of transmission resources the identification of a transmitter or receiver as a power saving UE may be included in a message reserving resources. When a UE attempts to reserve resources the UE can decide whether to pre-empt reserved resources based on whether the resources are reserved for a power saving UE.

Description

Power Saving for Sidelink Communications

Technical Field

The following disclosure relates to periodic resource reservations in cellular networks, and in particular to such reservations for sidelink communications.

Background

Wireless communication systems, such as the third-generation (3G) of mobile telephone standards and technology are well known. Such 3G standards and technology have been developed by the Third Generation Partnership Project (3GPP) (RTM) . The 3rd generation of wireless communications has generally been developed to support macro-cell mobile phone communications. Communication systems and networks have developed towards a broadband and mobile system.

In cellular wireless communication systems User Equipment (UE) is connected by a wireless link to a Radio Access Network (RAN) . The RAN comprises a set of base stations which provide wireless links to the UEs located in cells covered by the base station, and an interface to a Core Network (CN) which provides overall network control. As will be appreciated the RAN and CN each conduct respective functions in relation to the overall network. For convenience the term cellular network will be used to refer to the combined RAN &CN, and it will be understood that the term is used to refer to the respective system for performing the disclosed function.

The 3rd Generation Partnership Project has developed the so-called Long Term Evolution (LTE) system, namely, an Evolved Universal Mobile Telecommunication System Territorial Radio Access Network, (E-UTRAN) , for a mobile access network where one or more macro-cells are supported by a base station known as an eNodeB or eNB (evolved NodeB) . More recently, LTE is evolving further towards the so-called 5G or NR (new radio) systems where one or more cells are supported by a base station known as a gNB. NR is proposed to utilise an Orthogonal Frequency Division Multiplexed (OFDM) physical transmission format.

The NR protocols are intended to offer options for operating in unlicensed radio bands, to be known as NR-U. When operating in an unlicensed radio band the gNB and UE must compete with other devices for physical medium/resource access. For example, Wi-Fi (RTM) , NR-U, and LAA may utilise the same physical resources.

A trend in wireless communications is towards the provision of lower latency and higher reliability services. For example, NR is intended to support Ultra-reliable and low-latency communications (URLLC) and massive Machine-Type Communications (mMTC) are intended to provide low latency and high reliability for small packet sizes (typically 32 bytes) . A user-plane latency of 1ms has been proposed with a reliability of 99.99999%, and at the physical layer a packet loss rate of 10 ^-5 or 10 ^-6has been proposed.

mMTC services are intended to support a large number of devices over a long life-time with highly energy efficient communication channels, where transmission of data to and from each device occurs sporadically and infrequently. For example, a cell may be expected to support many thousands of devices.

The disclosure below relates to various improvements to cellular wireless communications systems.

Summary

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

The invention is defined by the appended claims in which there is required a method of transmission resource selection performed by a UE in a cellular network, the method comprising the steps ofidentifying a set of potentially available transmission resources, wherein transmission resources reserved for transmission to or from a power saving UE are not considered to be available dependent on a first criteria; andselecting transmission resources from the set of potentially available transmission resources for use for transmission by the UE.

The first criteria may be the identification of the transmitter or recipient of the transmission on the reserved resources being a power saving UE.

The power saving UE may be identified by an indication in a first-stage SCI or a second stage SCI.

The indicationmay comprise a bit flag.

The indication may comprise a partial or full UE ID.

The first criteria may be the priority of the reserved resources, wherein the priority is increased due to the resources being reserved in relation to a power saving UE

The set of potentially available resources may be identified based on a comparison of received signals to a threshold.

The first criteria may be the RSRP of a received signal compared to threshold, wherein the threshold or the RSRP is adjusted due to the reservation being in relation to a power saving UE.

There is also required a method of transmission resource selection performed by a UE in a cellular network, the method comprising the steps ofidentifying a set of potentially available transmission resources based on a comparison of received signals to a threshold, repeating the step of identifying potentially available resources based upon a lowered threshold, except for transmission resources reserved for transmissions to or from a power saving UE for which the original threshold is applied at each repetition.

The threshold for transmission resources reserved for transmissions to or from a power saving UE may only not adjusted if the priority is above a threshold.

There is also required a method of data transmission between UEs, the method comprisingtransmitting a first-stage SCI message from a UE intending to make a transmission, wherein the first-stage SCI includes an indication whether the recipient or transmitter of the transmission is a power saving UE; andtransmitting a second-stage SCI, and subsequently transmitting data in resources indicated by the second stage SCI.

The indication may comprise a bit flag.

The indication may comprise at least part of the recipient’s identity.

The indication may be sent by re-use of an existing field in the first-stage SCI, preferably within the frequency resource assignment or modulation and coding schemes fields.

The indication may comprise one bit to indicate whether the recipient UE is a power saving UE and one to indicate whether the transmitter is a power saving UE.

There is also required a UE configured to perform the methods described herein.

Brief description of the drawings

Further details, aspects and embodiments of the invention will be described, by way of example only, with reference to the drawings. Elements 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 respective drawings to ease understanding.

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

Detailed description of the preferred embodiments

Those skilled in the art will recognise 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.

Figure 1 shows a schematic diagram of three base stations (for example, eNB or gNBs depending on the particular cellular standard and terminology) forming a cellular network. Typically, each of the base stations 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 (RAN) . Each base station provides wireless coverage for UEs in its area or cell. The base stations are interconnected via the X2 interface and are connected to the core network via the S1 interface. As will be appreciated only basic details are shown for the purposes of exemplifying the key features of a cellular network. A PC5 interface is provided between UEs for SideLink (SL) communications. The interface and component names mentioned in relation to Figure 1 are used for example only and different systems, operating to the same principles, may use different nomenclature.

The base stations each comprise hardware and software to implement the RAN’s functionality, including communications with the core network and other base stations, carriage of control and data signals between the core network and UEs, and maintaining wireless communications with UEs associated with each base station. The core network comprises hardware and software to implement the network functionality, such as overall network management and control, and routing of calls and data.

In addition to uplink/downlink communications between UEs and base stations, sidelink communications may also be implemented in which UEs communicate directly with each other. Figure 2 illustrates a base station 102 forming a RAN, and a sidelink transmitter (SL Tx UE) UE 150 and a sidelink receiver (SL Rx UE) UE 152 in the RAN. UEs 150 and 152 are described as transmitter and receiver only for the purposes of explanation during a particular communication, and their roles may equally be reversed. The base station 102 is arranged to wirelessly communicate over respective connections 154 with each of the SL Tx UE 150 and the SL Rx UE 152. The SL Tx UE 150 and the SL Rx UE 152 are arranged to wirelessly communicate with each other over a sidelink 156.

Sidelink transmissions utilise TDD (half duplex) on either a dedicated carrier, or a shared carrier with conventional Uu transmissions between a base station and UE. Resource pools of transmission resources are utilised to manage resource and allocation and manage interference between potentially concurrent transmissions. A resource pool is a set of time-frequency resources from which resources for a transmission can be selected. UEs can be configured with multiple transmit and receive resource pools.

Two modes of operation are used for resource allocation for sidelink communication depending on whether the UEs are within coverage of a cellular network. In Mode 1, the V2X communication is operating in-coverage of the base stations (eg eNBs or gNBs) . All the scheduling and the resource assignments may be made by the base stations.

Mode 2 applies when the sidelink services operate out-of-coverage of cellular base stations. Here the UEs need to schedule themselves. For fair utilization, sensing-based resource allocation of transmission resources is generally utilised by the UEs. It is expected that resource selection will comprise two steps. In a first step a UE will identify resources that are considered available for selection, and in a second step specific resources will be selected for a transmission. The first step may be conducted by starting with a set of all resources within a selection window and removing those which are not considered candidates (for example resources reserved by another UE with an SL-RSRP above a threshold) . The step of selecting resources may be a random selection, potentially with constraints such as HARQ timing and delay between resources.

In Mode 2, UEs select transmission resources they wish to use for a transmission and transmit a Sidelink Control Information (SCI) message indicating those resources . The SCI notifies the recipient (which may be a single UE in unicast, a group of UEs in groupcast, or all reachable UEs in broadcast) of the details of the transmission it can expect.

Existing development of sidelink communications has focussed on “always-on” devices for which power consumption is not a significant concern. The following disclosure addresses power saving concerns which may become relevant when utilising sidelink communications with UEs with a limited power budget (so-called Power Saving UEs (PSUEs) ) . In particular the disclosure focusses on resource selection when UEs are operating in Mode 2 and seeks to provide mechanisms to reduce wasted transmissions and protect resources used for transmissions to and from PSUEs.

Examples set out below seek to reduce power consumption by improving transmission reliability and hence reduce the number of repetitions required to achieve a given quality of service. This may be achieved by protecting the resources used by transmissions to and from PSUEs to avoid collisions. The presence of a PSUE as transmitter or receiver in a sidelink communication may be indicated to other UEs, for example in the messages reserving the transmission resources, such as a Sidelink Control Information (SCI) message.

An indication may be added to the first-stage SCI messages indicating that the message is for a PSUE. PSUEs therefore only need to decode the second-stage SCI message when this indication is present, thereby reducing power consumption for wasted decodes. Furthermore, non-PSUEs may perform resource reselection when they detect a collision with resources selected by a PSUE. This reduces collisions with PSUE transmissions hence improving the reliability of the PSUE transmission, and potentially reducing the repetitions required. Also, it is disclosed below to perform resource allocation without a pre-emption verification or re-evaluation prior to transmission by a PSUE. This may increase the possibility of a collision, but in combination with the other techniques discussed herein for protecting PSUE resources is intended to make PSUE transmissions more power efficient.

Details of these various techniques are set out below.

A sidelink transmission may collide with another sidelink transmission from a different UE or the resources may be pre-empted by another UE if permitted for the relevant Resource Pool (RP) . Due to collisions and/or pre-emptions UEs need to perform additional (re-) transmissions to reach a certain target quality of service (QoS) , those additional (re-) transmissions increase the power consumption of the UEs, which is a particular difficulty for PSUEs.

To reduce the need for additional transmissions, pre-emption may not be permitted for resources reserved for a transmission by a PSUE.

Prevention of pre-emption of PSUE transmission resources may be implemented by removing resources reserved for a PSUE transmission from the pool of resources from which resources can be selected when preparing for a transmission. That is, the PSUE-reserved resources are not considered available for selection, regardless of the resource pool configuration, relative priorities or RSRP thresholds. The transmission resources reserved by a PSUE cannot therefore be pre-empted and hence will be available for the planned transmission.

Preventing any pre-emption offers a high level of protection to PSUE transmission, which may be greater than is appropriate for general network performance. This may be addressed using the following techniques. Autonomous resource selection for sidelink devices (Mode 2 discussed above) works in 2 steps:

i. The first step aims at identifying a set of resources that are considered available by removing all the resources with respect to a configured reference symbol received power (RSRP) thresholds. For this purpose, RSRP thresholds are configured for pairs of priorities, where one priority is for the intended transmission and the other priority is for the transmission detected/sensed. This step should provide at least X%of resources, otherwise the RSRP thresholds are relaxed and this step of resource identification is repeated.

ii. The second step will select resource (s) , primarily in a random manner, though with some constraints (e.g. feedback timing or delay between the resources when multiple resources need to be selected) .

Limited pre-emption of PSUE-reserved resources may be allowed by keeping the resources as available in the first step of resource identification, but freezing RSRP thresholds for the power saving UEs’ reservations when iterating the resource selection algorithm. The resources can therefore be pre-empted, but only against a higher criteria than other resources. In addition, the RSRP thresholds may be frozen for PSUE transmissions if their priority is higher than a configured threshold.

There is therefore provided a method of transmission resource selection in which a UE selects resources for transmission from a pool of available resources. In a first example, resources reserved by a PSUE are excluded from the pool of available resources. In a second example, when RSRP thresholds for selecting resources are adjusted for non-PSUE-reserved resources when iterating the selection process but are frozen for PSUE-reserved resources. Furthermore, the RSRP thresholds may be frozen only if the transmission’s priority is higher than a configured threshold.

To prevent pre-emption UEs must be able to identify reservations made by PSUEs. Such an indication may be provided in the SCI which reserves the resources. In a first example the indication may be carried in the first-stage SCI, for example using one or more of the reserved bits in that message, or may be carried in the second-stage SCI. Other UEs detecting the SCI can thus identify the resources as reserved for a PSUE transmission and treat them appropriately during resource selection.

As well as transmissions, reception also consumes power as the UE must wake up to receive and decode the signals. If an expected transmission is not received the power consumed in waking up is wasted, and a further transmission opportunity must be utilised to transmit and receive the data. If a second UE selects resources scheduled for transmission to a PSUE, the collision may prevent successful decoding of the data, or if the original reservation is cancelled the PSUE will wake up and listen for a transmission that is not made. A further transmission is then required to complete the transmission successfully. All of this results in increased power consumption for PSUE.

In order to mitigate these problems, transmissions to PSUEs may be protected from selection or pre-emption. These techniques described above for protection of transmissions by a PSUE apply equally to transmissions to a PSUE. The resources may be removed from the pool of available resources, or the techniques such as freezing the RSRP threshold discussed above may be utilised.

In order to identify the transmissions to PSUEs for protection an indication that a transmission will be destined to a PSUE is required. This may be implemented as discussed above for transmissions by a PSUE, for example by including the indication in the SCI reserving the resources. A transmitter UE may know the destination is a PSUE through various mechanisms. Prior to data transmission, during the configuration phase, higher layers will exchange the information of a UE being a PSUE. For broadcast transmissions, if a transmitter knows from the message content that it is destined to one or more PSUE (s) , it may flag the transmission destined to PSUE.

The conventional sidelink transmission process utilises a two stage SCI in which the first stage SCI does not include an indication of the source or destination of the scheduled transmission. Sidelink devices must therefore monitor and decode both the first and second stage SCI to be able to identify whether a scheduled transmission is for them. To decode both stages of the SCI a UE must receive the first stage SCI in the first 2 or symbols of a slot, receive sufficient data (shared channel) DMRS signals to prepare a channel estimate, and then receive and decode the second stage SCI embedded in the PSSCH. This requires significant time and power consumption in order to determine whether a transmission is for the UE, which power is wasted if the transmission is not for the UE.

To address this disadvantage the first stage SCI may include an indication that a transmission is to a PSUE. If a PSUE receives and decodes a first stage SCI which does not indicate that a PSUE is the destination then the PSUE does not need to attempt to receive the second stage SCI as it knows the transmission is not for it. The PSUE can thus return to sleep after decoding the first stage SCI, thereby conserving power. If the first stage SCI does indicate the transmission is for a PSUE then the PSUE can continue to receive DMRS and the second stage SCI to identify whether the transmission is for it.

The indication of a PSUE recipient in the first-stage SCI may be carried as a yes/no indication, for example as a single bit in order to minimise the signalling overhead. This is efficient for signalling overhead, but requires all PSUEs receiving the message to proceed to decode the second-stage SCI. More granularity can be provided by indicating part of the ID (for example the last x bits) of the recipient UE such that UEs whose ID does not match the indicated part do not need to proceed to receive and decode the second stage SCI. There is therefore a trade off between signalling overhead and the number of UEs which unnecessarily decode the second stage SCI.

There is provided a method of data transmission between UEs, comprising transmitting a first-stage SCI message from a UE intending to make a transmission, wherein the first-stage SCI includes an indication whether the recipient of the transmission is a PSUE. The indication may be a flag, comprising a single bit, or may comprise part of the recipient UE’s ID. A receiver UE receiving a first stage SCI including an indication whether the recipient UE is a PSUE may decode the indication and if the indication is that the recipient 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 with reception of the second stage SCI. Since the first-stage SCI includes the information on resources being reserved for the transmission, only receiving the first stage SCI still permits the UE to maintain awareness of reserved transmission resources for use when planning its own transmissions. The indication in the first stage SCI that the recipient is a PSUE can be utilised in conjunction with any of the above disclosure to protect the resources reserved by the SCI.

In an example the indication of a PSUE recipient may be included using one (or more) of the reserved bits in the first stage SCI which are configured by the higher layer (RRC) parameter “sl-NumReservedBits” . Alternatively, one bit in an existing field may be re-used for this purpose, for example a bit of the “Frequency resource assignment” or “Modulation and Coding scheme” may be utilised to indicate a PSUE as the recipient. For groupcast and broadcast transmissions, if at least one PSUE is part of the intended recipients, the PSUE indication can be flagged (which is also the case for all aspects of the current disclosure) .

The first stage SCI may also (or instead of) include an indication that the transmission is originating from a PSEU for use as set out above. Two bits can be utilised, one to indicate the source as a PSUE and one to indicate the recipient as a PSUE. To reduce the signalling overhead one bit could be used to indicate if one or both of the transmitter and the receiver is a PSUE. Using a single bit for both possibilities does, however, remove the advantage of preventing a PSUE from decoding the second stage SCI as the UE cannot discriminate between the transmitter or receiver being the PSUE.

In conventional sidelink operation, provided pre-emption is activated for the relevant resource pool, if a UE detects a reservation over its pre-reserved resources it will trigger re-selection for its own transmission if the new reservation results from a pre-emption by another UE with a higher priority than the pre-empted transmission. If the pre-empted UE is a PSUE under the conventional procedure it will still perform re-selection, thereby incurring the power consumption penalty of the re-selection process, or the transmission will lead to a collision and likely a requirement for retransmission which also carries a power consumption penalty.

To avoid PSUEs having to re-select resources, and to avoid collisions, if a UE detects a colliding reservation from a PSUE (for example this may be detected during the re-evaluation phase of sidelink transmission) it considers its own reservation pre-empted by the PSUE regardless of the relative priorities. That is, the PSUE is given priority access to the transmission resources to avoid the PSUE having to re-select resource thereby avoiding the power penalty of that re-selection process. Instead the other UE (which is assumed to not be a PSUE) , even though on the conventional process it could transmit and collide with the PSUE’s transmissions, performs a reselection process to avoid collision with the PSUE. The same principles can be applied to transmissions where a PSUE is the receiver. Power consumption penalties due to reselections and collisions by PSUEs are therefore avoided.

In an alternative approach, rather than fully preventing pre-emption or colliding transmissions with PSUE transmissions, the priority of PSUE transmissions can be increased to make it less likely the resources will be pre-empted. This allows pre-emption where there is a large difference in priorities, implying the conflicting transmission is very important or time-sensitive, but for most cases allows the PSUE transmission to continue. The MAC or PHY layers can update the priority level of transmissions made to and/or from a PSUE.

There is disclosed a method of sidelink transmission in which prior to making a transmission a UE checks for conflicting resource reservations, and if a conflicting reservation for a transmission from and/or to a PSUE is detected, the UE does not proceed with its transmission and reselects resources for the transmission. Optionally, the priority of the PSUE transmission may be increased due to it involving a PSUE and pre-emption may be permitted based on this modified priority.

In the conventional transmission process, when pre-emption is enabled for a resource pool prior to transmission the MAC layer requests the PHY layer to verify that reserved resources are still available (i.e. the reservation has not been pre-empted) . However, this verification can consume significant power which is undesirable for PSUEs. Power consumption can be reduced by not performing this verification check, but this can increase the number of collisions and hence degrade overall system performance. Performance may be retained, even with no verification check, by preventing pre-emption of resources reserved for transmissions to and/or from PSUEs. The non-PSUEs will thus reselect resources to avoid a collision with the PSUE reservations. The power consumption of the non-PSUEs, and the timing of transmissions, are thus affected as they are forced to reselect resources, but this may not be a significant disadvantage.

To enable compatibility between UEs which do, and do not, support protection for PSUEs it may be efficient to allocate resource pools depending on the support available. For example, one resource pool may be utilised for PSUEs and UEs which do support protection, and a second resource pool for UEs which do not support protection for PSUEs. This arrangement ensures all UEs which may receive an indication that a transmission relates to a PSUE can decode and act appropriately based on the indication.

Various methods have been disclosed to protect PSUE transmission resources to improve consumption by PSUEs relating to sidelink transmissions.

Although not shown in detail any of the devices or apparatus that form part of the network may include at least a processor, a storage unit and a communications interface, wherein the processor unit, storage unit, and communications interface are configured to perform the method of any aspect of the present invention. Further options and choices are described below.

The signal processing functionality of the embodiments of the invention especially the gNB and the UE may be achieved using computing systems or architectures known to those who are skilled in the relevant art. Computing systems such as, a desktop, laptop or notebook computer, hand-held computing device (PDA, cell phone, palmtop, etc. ) , mainframe, server, client, or any other type of special or general purpose computing device as may be desirable or appropriate for a given application or environment can be used. The computing system can include one or more processors which can be implemented using a general or special-purpose processing engine such as, for example, a microprocessor, microcontroller or other control module.

The computing system can also include a main memory, such as random access memory (RAM) or other dynamic memory, for storing information and instructions to be executed by a processor. Such a main memory also may be used for storing temporary variables or other intermediate information during execution of instructions to be executed by the processor. The computing system may likewise include a read only memory (ROM) or other static storage device for storing static information and instructions for a 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, a floppy disk drive, a magnetic tape drive, an optical disk drive, a compact disc (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, a 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 media drive. The storage media may include a computer-readable storage medium having particular computer software or data stored therein.

In alternative embodiments, an 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, a removable storage unit and an interface , such as a program cartridge and cartridge interface, a removable memory (for example, a flash memory or other removable memory module) and memory slot, and other removable storage units and interfaces that allow software and data to be transferred from the removable storage unit to computing system.

The computing system can also include a communications interface. Such a communications interface can be used to allow software and data to be transferred between a computing system and external devices. Examples of communications interfaces can include a modem, a network interface (such as an Ethernet or other NIC card) , a communications port (such as for example, a universal serial bus (USB) port) , a PCMCIA slot and card, etc. Software and data transferred via a communications interface are in the form of signals which can be electronic, electromagnetic, and optical or other signals capable of being received by a communications interface medium.

In this document, the terms ‘computer program product’ , ‘computer-readable medium’ and the like may be used generally to refer to tangible media such as, for example, a memory, storage device, or storage unit. These and other forms of computer-readable media may store one or more instructions for use by the processor comprising the computer system to cause the processor to perform specified operations. Such instructions, generally 45 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 a processor to perform specified operations, be compiled to do so, and/or be combined with other software, hardware, and/or firmware elements (e.g., libraries for performing standard functions) to do so.

The non-transitory computer readable medium may comprise at least one from a group consisting of: 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, EPROM, an Electrically Erasable Programmable Read Only Memory and a Flash memory. In an embodiment where the elements are implemented using software, the software may be stored in a computer-readable medium and loaded into computing system using, for example, removable storage drive. A control module (in this example, software instructions or executable computer program code) , when executed by the processor in the computer system, causes a processor to perform the functions of the invention as described herein.

Furthermore, the inventive concept can be applied to any circuit for performing signal processing functionality within a network element. It is further envisaged that, for example, a semiconductor manufacturer may employ the inventive concept in a design of a stand-alone device, such as a microcontroller of a digital signal processor (DSP) , or application-specific integrated circuit (ASIC) and/or any other sub-system element.

It will be appreciated that, for clarity purposes, 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 way of a plurality of different functional units and processors to provide the signal processing functionality. Thus, 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 organisation.

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 elements 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 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 present invention is limited only by the accompanying claims. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognise 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, for example, 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. Also, 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. In addition, singular references do not exclude a plurality. Thus, references to ‘a’ , ‘an’ , ‘first’ , ‘second’ , etc. do not preclude 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 present invention is limited only by the accompanying claims. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognise that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term ‘comprising’ or “including” does not exclude the presence of other elements.

Claims

A method of transmission resource selection performed by a UE in a cellular network, the method comprising the steps of

identifying a set of potentially available transmission resources, wherein transmission resources reserved for transmission to or from a power saving UE are not considered to be available dependent on a first criteria; and

selecting transmission resources from the set of potentially available transmission resources for use for transmission by the UE.
The method of claim 1, wherein the first criteria is the identification of the transmitter or recipient of the transmission on the reserved resources being a power saving UE.
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.
The method of claim 3, wherein the indication comprises a bit flag.
The method of claim 3 or 4, wherein the indication comprises a partial or full UE ID.
The method of claim 1, wherein the first criteria is the priority of the reserved resources, wherein the priority is increased due to the resources being reserved in relation to a power saving UE
The method of claim 1, wherein the set of potentially available resources is identified based on a comparison of received signals to a threshold.
The method of claim 1, wherein the first criteria is the RSRP of a received signal compared to threshold, wherein the threshold or the RSRP is adjusted due to the reservation being in relation to a power saving UE.
A method of transmission resource selection performed by a UE in a cellular network, the method comprising the steps of

identifying a set of potentially available transmission resources based on a comparison of received signals to a threshold,

repeating the step of identifying potentially available resources based upon a lowered threshold, except for transmission resources reserved for transmissions to or from a power saving UE for which the original threshold is applied at each repetition.
The method of claim 9, wherein the threshold for transmission resources reserved for transmissions to or from a power saving UE is only not adjusted if the priority is above a threshold.
A method of data transmission between UEs, the method comprising

transmitting a first-stage SCI message from a UE intending to make a transmission, wherein the first-stage SCI includes an indication whether the recipient or transmitter of the transmission is a power saving UE; and

transmitting a second-stage SCI, and subsequently transmitting data in resources indicated by the second stage SCI.
The method of claim 11, wherein the indication comprises a bit flag.
The method of claim 11 or claim 12, wherein the indication comprises at least part of the recipient’s identity.
The method of any of claims 11 -13 wherein the indication is sent by re-use of an existing field in the first-stage SCI, preferably within the frequency resource assignment or modulation and coding schemes fields.
The method of any of claims 11 to 13 wherein the indication comprises one bit to indicate whether the recipient UE is a power saving UE and one to indicate whether the transmitter is a power saving UE.
A UE configured to perform the method of any of claims 1 to 15.