WO2020259329A1

WO2020259329A1 - Sidelink resource allocation

Info

Publication number: WO2020259329A1
Application number: PCT/CN2020/096042
Authority: WO
Inventors: Sebastian Wagner
Original assignee: JRD Communication (Shenzhen) Ltd.
Priority date: 2019-06-27
Filing date: 2020-06-15
Publication date: 2020-12-30
Also published as: CN113196853B; CN113196853A

Abstract

Methods to increase resource availability for sidelink communications in a wireless cellular communication system. Resources in addition to those in predefined resource pools may be assigned for sidelink communications using signalling from a base station to a UE. SCI messages may be used to share the indication to other UEs. Resources may be activated indefinitely, or for a validity period.

Description

Sidelink Resource Allocation

Technical Field

The following disclosure relates to the allocation of transmission resources in a cellular communications network, and specifically the allocation of resources 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) . 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.

In conventional cellular communication networks, all signalling is between each mobile device and a base station rather than directly between mobile devices, even if the mobile devices are within wireless communication range of each other. This may lead to inefficient use of wireless transmission resources and may increase base station resource utilisation. Sidelink communications allow mobile devices to communicate directly rather than via a base station, potentially improving wireless and base station resource utilisation. Sidelink communications are considered particularly interesting for Machine to Machine communications, particularly Vehicle to Vehicle (V2V) and Vehicle to Everything/Anything (V2X) communications.

The disclosure below relates to various improvements to cellular wireless communications systems, and in particular sidelink communications in such 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.

There is provide a method of activating additional resources for sidelink communications in a wireless cellular communication system, the method comprising the steps of transmitting an indication from a base station to a UE of additional resources to be available for sidelink transmissions. The indication may be transmitted to a first UE which subsequently transmits an indication of the resources to a second UE via an SCI message. Alternatively, the indication may be transmitted to all relevant UEs directly from the base station. The resources may be indicated by a bitmap with each bit relating to a slot, or by reference to predefined complementary resource pool.

A validity period may be defined during which the resources remain available without further indications, and after which the resources are automatically no longer available. Any appropriate signalling may be utilised, for example DCI, SCI, or RRC depending on the nature of the desired update, overhead priorities and the elements involved in any update.

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.

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.

Figure 1 shows a schematic diagram of selected components of a cellular communication system;

Figure 2 shows an example of two resource pools;

Figure 3 shows an example of additional resource allocation;

Figure 4 shows an example of utilising additional resources;

Figure 5 shows a flow chart for allocating additional resources;

Figure 6 shows an example of complementary resource pools; and

Figure 7 shows a flow chart for activating complementary resource pools.

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. In the proposed NR protocols, the Uu interface is between the base station and UEs. 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.

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.

In LTE-V2X (Rel 14) Resource pools may be configured via cell-specific signalling (SIB 21) or RRC signalling. The basic information element (IE) is SL-CommResourcePoolV2X-r14 defined in TS 36.331 (e.g V14.5.1) which has the parameters shown in Table 1 below: -

Table 1: Time-frequency parameters in resource pool configuration SL-CommResourcePoolV2X-r14.

TS 36.331 also defines (Section 14.1.5) how resource pools are defined based on these parameters. All subframes starting from system frame number (SFN) 0 or Direct Frame Number (DFN) 0 (depending if the UE is in-coverage or out-of-coverage) respectively, are available for SL transmission except: -

1. subframes in which SLSS resource is configured.

2. downlink subframes and special subframes if the sidelink transmission occurs in a TDD cell.

3. Certain special reserved subframes.

The remaining subframes are arranged in increasing order of subframe index, and the configured bitmap sl-Subframe-r14 is applied, where a 1 indicates the subframe is including in the pool, and 0 that it is not. In the frequency-domain, PRBs included in the resource pool are given by n _PRB = n _subCHRBstart + mn _subChsize + j, where m = 0, 1, …, N _subCH -1 with n _subCHRBstart, n _subChsize and N _subCH specified by the higher layer parameters startRB-Subchannel-r14, sizeSubchannel-r14 and numSubchannel-r14, respectively.

As noted above, DL and certain special reserved subframes are not available for use in the sidelink resource pool to avoid the possibility of interference to system information. That is, only UL subframes are available for SL resource pools.

In previous standards (In particular LTE) subframes are specified as UL or DL, with various configurations being available as specified in Table 4.2-2 of TS 36.331) . Up to 6 subframes in a frame may be defined as UL, thus giving the maximum resources available for sidelink communications.

In LTE-V2X selection of resources for a specific transmission can be performed according to two allocation modes. In mode 3 the base station allocates sidelink resources and the UEs cannot alter them. In mode 4, each UE autonomously selects resources for each transmission from its allocated resource pool.

In mode 3, a UE transmits a scheduling request (SR) or buffer status report (BSR) to the relevant base station, and the base station responds with a DCI (Format 5A0 on PDCCH to grant the sidelink transmission. The UE then transmits PDSCH on the first available subframe 4 + m ms after reception of the DCI, where the offset m ∈ {0, 1, 2, 3} is only signalled in the DCI for TDD operation. The first available subframe is selected from all resource pools configured for the UE, and hence if the base station intends transmission on a specific resource pool the DCI must be time appropriately. The first available subframe may be part of more than one resource pool hence leading to ambiguity which is resolved by the frequency resource allocation.

The NR standards include a number of differences that may make existing sidelink resource allocation procedures inappropriate. For example: -

● Different numerologies: A slot is the basic time interval and its length depends on the sub-carrier spacing

● Flexible TDD:

a. There is no set of pre-configured UL-DL configurations but the number of UL and DL slots and symbols can be configured in a flexible way.

b. As well as UL and DL slots/symbols, there are Flexible (F) slots/symbols which can be used for either UL or DL

c. There is no cell-wide UL-DL configuration only: The F slots/symbols in the cell-wide configuration can be overwritten by UE-specific configurations. It is also possible to overwrite it through dynamic signalling via DCI 2.0.

● New services: It is likely that a resource pool supports broadcast, group-cast and uni-cast transmissions which all have different throughput, reliability and latency requirements.

In NR the cell-specific (common) TDD UL-DL configuration (TDD-UL-DL-ConfigCommon) is acquired in the IE ServingCellConfigCommonSIB signalled in SIB1 and includes a reference sub-carrier spacing and up to two UL-DL patterns. For the purposes of explanation only, an example of 15kHz sub-carrier spacing the pattern shown Table 2 below will be utilised: -

Table 2: Example configuration of TDD-UL-DL-Pattern.

The configuration defined by Table 2 is shown in Figure 2. Figure 2 shows two repetitions of the 10-slot (10ms) UL/DL pattern and resource pools with a length of 20 slots (20 ms) . 6 frequency sub-channels are shown.

Two resource pools are shown in Figure 2 –RP0 and RP1. RP0 uses only UL slots, while RP1 uses both uplink and flexible slots. RP0 has resources available every 10ms, but due to the use of the flexible slots for RP1 that resource pool has resources available more frequently thus potentially reducing latency. However, UEs monitor for a PSCCH transmission on every slot in their configured resource pool (s) and hence RP1 requires more frequent monitoring than RP0 leading to potentially greater power consumption.

Two resource allocation modes are available –mode 1 and mode 2. In mode 1 the base station configures the sidelink resources, whereas in mode the UE selects them autonomously from preconfigured resources. In mode 2 a UE may not be allowed to transmit on flexible slots because it can unknowingly cause interference to adjacent cells that may use those slots for DL transmissions.

Set out below are resource allocation methods which seek to address drawbacks with the techniques disclosed hereinbefore.

As shown in Figure 2, some slots are “partial slots” which may contain DL & F or UL & F regions. That is, part of the slot may be for DL and part may be flexible (similarly, part may be used for UL and part flexible) . Such UL/F partial slots could also be included in a sidelink resource pool.

In order to reduce monitoring occasions, UEs may be configured to only monitor for PSCCH on full/partial UL slots, even if the resource pool includes flexible slots. For example, in Figure 2, a UE configured with RP1 may only monitor for PSCCH in

slots

8, 9, 17, and 18. Furthermore, control information may only be able to be transmitted on full DL slots, and hence monitoring may not be required in slot 17, leaving only 8, 9, and 18 to be monitored.

The configuration of slots to monitor can be made via any appropriate signalling mechanism, for example RRC or DCI/SCI. An example signalling scheme is shown in Table 3 below: -

Table 3: Example possible PSCCH monitoring configurations per UE per RP.

Reducing the number of slots to monitor for PSCCH may reduce power consumption, without reducing the number of slots available for SL transmissions.

The availability of flexible slots within a resource pool may be configured dynamically, for example using DCI/SCI signalling. In a particular example a bitmap may be utilised to indicate availability. The bitmap’s length equals the number of full or partial slots containing flexible resources in one UL/DL pattern period. When a bit is set to 1 the corresponding slot is available for SL transmission, and when set to 0 the corresponding slot is not available. When a slot is indicated as available the frequency resources are the same as those of the resource pool (s) configured for the UE.

Figure 3 shows the same RP0 and RP1 as Figure 3, but with two additional sets of resources (Add RP0, Add RP1) that can be added to each resource pool as indicated by dynamic signalling. In this example, the bitmap’s length is 6, corresponding to flexible slots 2 –7 (and 12 –17) .

A resource pool configured for a UE may indicated a certain slot is available, but the bitmap may indicate the slot is not available, which contradiction must be resolved according to defined rules. For example, as occurs at slot 13 of Figure 4. There are two principle options: -

● Resource pool configuration has priority over bitmap: Bitmap cannot overwrite resource pool configuration. According, in Figure 4 slot 13 would be available for SL transmission.

● Bitmap has priority over resource pool configuration: Bitmap overwrites resource pool configuration such that in Figure 4 slot 13 would not be available for SL transmission.

Since the intention of dynamic signalling is to enable more flexible reconfigurations, the second option is likely to be most attractive to allow the network to modify previous semi-static configurations. A bitmap is only used as an example of a possible signalling mechanism, and any suitable signalling means may be utilised according to these principles.

As noted above, in Mode 1 the base station selects the transmission resources to be used by a UE for an SL transmission and indicates those to the UE in a DCI message. For efficient decoding the size of the DCI message must be known before transmission, and so the indication of additional resources available for SL transmissions may be included in the DCI scheduling an SL transmission, or in a separate DCI that does not schedule an SL transmission (i.e. the DCI only modifies SL resource pool allocations) .

Higher layer, or dedicated, signalling may be utilised to activate or deactivate the availability of additional resource procedures. This activation or deactivation enables UEs to be aware which size and format of DCI message they are seeking to decode (with or without the possible additional resource indication) . Once the UE knows if the procedures are activated it knows which sizes of DCI to search for.

Once a UE (TX-UE) receives the DCI it must forward the information to the UE (RX-UE) which is to receive the transmission such that the additional resources can be utilised. This may be achieved using the method shown in Figures 4 & 5. In an alternative arrangement the base station may forward the resource information (e.g. a bitmap indication) directly to the RX-UE.

At step 500 the DCI message 400 is received at the TX-UE. The DCI includes scheduling information for an SL transmission to an RX-UE, and an indication of additional resources (for example in the form of the bitmap discussed above) available for SL transmissions. The TX-UE decodes the DCI and determines at step 501 the first slot in which the SCI can be transmitted. In this case it is slot 5 (N + 4 = 5) , but there are no transmission resources available in slot 5.

At this stage only resources in the resource pool are available since the TX-UE has not yet forward an indication of any additional resources allocated by the base station in the DCI. The first available transmission resources are therefore in RP1 in slot 8. TX-UE therefore transmits the relevant SCI in slot 8 at step 502, including the indication of additional resources as received from the base station.

At step 503 the RX-UE decodes the SCI transmitted in slot 8, and the associated PSSCH if in the same slot. At step 504 the RX-UE identifies the additional resources indicated as available and assigns those as part of the RP1 resources such that resources in

slots

12, 14, and 15 also become available. Any appropriate technique may be utilised to relate the additional resources to a resource pool. For example, the UE may identify that the resources are in relation to RP1 implicitly from the timing constraints for transmission of SCI (N+4 from DCI) . Since the base station knows all allocated resource pools it can target the desired resource pool by the message timing. In another example explicit signalling may be utilised, for example in DCI, to indicate the resource pool, for example using an RP-ID.

At step 505 additional DCI messages may be received in

slots

5, 6, 7, and 8 scheduling SL transmissions in

slots

12, 13, 14, and 15 which can be made using the newly assigned additional resources. The indication of additional resources, for example using a bitmap, thus enables additional transmission resources for SL transmissions.

The indication of additional resources may be included in every SCI and assumed to remain valid until changed by a further DCI/SCI message. However, this may add significant overhead to the SCI message. A “validity period” may be defined in relation to the additional resources and the indication thereof such that after the validity period the additional resources are assumed to no longer be available and only the resource pool resources are available.

The validity period may be defined as starting once the SCI is received by the RX-UE (s) , or, if HARQ feedback is activated, once the PSFCH is received by the TX-UE following the first transmission of an SCI indicating the additional resources. The latter option ensures the RX-UE (s) has successfully decoded the SCI and is hence aware of the additional resources.

Similarly the period may be defined in a range of ways, for example: -

1. Number of UL-DL pattern periods after the start of the UL-DL pattern period in which the validity period starts. For example in Figure 4, for option 1 above, the validity period starts at slot 8 (SCI received) and hence the first period of the validity period is slots 0 –9, and the second period is slots 10 –19.

2. Defined as a time, for example ms, independent of the UL-DL periods. For example, assuming option 1 for the start point, a validity period of 5 ms would start at slot 8 and expire after slot 12 meaning only slot 12 was added to the resource pool

3. The validity period may be defined as a number of slots, which timing will depend on the numerology since the slot time depends on the sub-carrier spacing.

4. Defined in terms of resource pool periodicity. A parameter such as sl-Subframe-r14 defines the resource periodicity, e.g. 100 bits/SL slots. Hence, the original resource pool is not modified but the additional slots indicated are available for SL transmission. For instance, if the valid period is 2 resource pool periods, additional SL resources are available in the current resource pool period and in the next resource pool period.

The use of a validity period enables the additional resource indication to be only transmitted in the first DCI and the not repeated for the duration of the validity period, thus reducing signalling overhead.

As with DCI, UEs need to know the size of SCI messages they may need to decode. The additional resource indication can be included in an existing format, or a new format defined. Furthermore, where a 2-stage SCI procedure is utilised the resources may be indicated in the second stage SCI. In an alternative example, the first stage of the SCI procedure may be utilised. Using the first may be advantageous as it can be decoded by all UEs who can thus gain awareness of used resources. Similar to DCI, the overhead may be reduced by utilising a validity period as discussed above such that only the first SCI message within a validity period needs to include the indication of additional resources. Furthermore, the RX-UE does not need to attempt to decode an SCI format including the indication during the validity period.

In order to manage signalling overheard in relation to additional resources for sidelink communications one or more Complementary Resource Pools (CRPs) may be defined for use with standard resource pools to extend the resources available. The CRPs can be activated in a semi-static or dynamic manner using only a small overhead due the finite number of CRPs defined. Since frequency-domain resources in a resource pool are fixed, one or more CRPs can be associated to a resource pool.

Figure 6 shows an example of two CRPs defined in relation to the resource pools discussed in previous examples herein, and Figure 7 shows a flow chart of a method utilising semi-static configuration of CRPs.

At step 600 relevant UEs are configured (for example via RRC signalling) with resource pools RP0 and RP1, together with complementary resource pools CRP0 and CRP1. At step 601 UEs monitor PSCCH for SCI on the configured resource pool resources (but not on the CRP resources) . At step 602 the base station transmits a DCI message to a TX-UE to schedule an SL transmission, including an indication to activate the two CRPs. In a further example, only one CRP in which transmission will take place may be activated.

At step 603 the TX-UE decodes the DCI message and marks the relevant CRP as activated. At step 604 the TX-UE transmits an SCI message to the relevant RX-UE including an indication to activate the CRP as per the DCI indication. Once activated, from step 605, RX-UE monitors for SCI the CRPs as well as the resource pool resources. The CRPs remain active until indicated otherwise.

At step 606 a comparable DCI/SCI deactivation process can be utilised when the CRPs are no longer required.

Since in this example there are only two CRPs, and they remain active indefinitely, the signalling overhead is reduced compared to indicating each slot individually. For example, to indicate the two CRPs in this example, only 2 bits would be needed. Similarly, if only one CRP is defined a single bit is utilised. The activation/deactivation signal may utilise any appropriate signalling. For example, if a bit relating to a CRP is toggled the state of the CRP may be toggled as well, or if a bit is 0 the CRP is set to inactive, and if the bit is 1 the CRP is set to active.

In a variation of the above example, the base station may transmit a signal, for example a DCI signal, to all relevant UEs to activate CRPs rather than relay the indication via a TX-UE and SCI.

A similar validity period may be applied for the CRPs as described in relation to additional resources above. A validity period can be pre-configured with the CRP, semi-statically indicated through RRC signalling, or dynamically indicated through DCI/SCI signalling. The first two options avoid SCI/DCI overhead. The validity period may be indicated explicitly in the DCI/SCI message. As discussed above during the validity period an SCI format without the validity period indication may be utilised to reduce overhead.

If a UE switches from mode 1 to mode 2 resource allocation, all CRPs may be deactivated to avoid interference, but a mode 2 UE can still receive on resource pools and CRPs if activated by a TX-UE.

The association between resource pools and CRPs can be implicit based on them being related if a CRP uses the same frequency-domain resources as a resource pool or may be explicit by including an indication of the associated resource pool (for example using an RP-ID) in the configuration or activation signalling.

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) 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 activating resources for sidelink communications between UEs in a wireless cellular communication system, the method comprising

transmitting an indication from a base station of the cellular communication system to a UE indicating resources which are available for the UE for sidelink transmissions, wherein the resources indicated as available are slots defined as flexible by the cellular communication system.
A method according to claim 1, wherein the indication comprises a bitmap indicating the available resources, wherein each bit corresponds to a slot.
A method according to claim 1, wherein the indication comprises an indication of a resource pool, which resource pool includes slots defined as flexible by the cellular communication system.
A method according to any preceding claim, wherein the UE transmits a further indication of at least some of the available resources to a further UE in an SCI message.
A method according to any preceding claim, wherein the indication is in a DCI message.
A method according to any of claims 1 to 4, wherein the indication is in an RRC message.
A method according to any preceding claim, wherein the resources are available for a predefined validity period, at the end of which validity period the resources are no longer available.
A method according to claim 7, wherein the validity period is defined in relation to the UL/DL pattern periodicity, as a time interval, as a number of slots, or in relation to resource pool periodicity.
A method of monitoring for sidelink control channel transmissions by a UE in a cellular communications network, the method comprising

receiving a configuration message at the UE indicating a subset of slots within the UE’s resource pool which the UE should monitor for sidelink control transmissions; and

monitoring for a sidelink control transmission in the indicated subset of slots;

wherein the subset slots are (1) all sidelink slots, (2) only sidelink slots configured for full uplink, (3) only sidelink slots configured for full or partial uplink, or (4) only sidelink slots configured for partial uplink.