GB2552792A

GB2552792A - Methods and devices for resource selection for direct transmissions between wireless devices in a wireless communication system

Info

Publication number: GB2552792A
Application number: GB1613574.1A
Authority: GB
Inventors: Ron Roy; Palgy Michael
Original assignee: TCL Communication Ltd
Current assignee: TCL Communication Ltd
Priority date: 2016-08-08
Filing date: 2016-08-08
Publication date: 2018-02-14
Anticipated expiration: 2036-08-08
Also published as: GB2552792B8; GB2552792A8; CN110089174A; CN110089174B; GB2552792B; WO2018028417A1

Abstract

Methods and apparatus for selecting a resource for direct communications between wireless devices (102,108) via a side link (113) in a wireless communications system. The devices may consist of vehicle user equipment (V-UE), or pedestrian user equipment (P-UE) and the communication may be V2P (vehicle to pedestrian). A first wireless communications device (108), which may be a V-UE, monitors a plurality of resources in a resource pool allocated for use on the side-link during a first time interval. Information relating to the monitored resources is then broadcast to a second wireless communications device (102) which receives the information and selects a resource from the plurality of allocated side link resources based on the received information. The second device may be a P-UE. The broadcast information may contain indications of allocated resources available for selection by the second device which may be transmitted using a Physical Side link Shared Channel (PSSCH).

Description

(71) Applicant(s):

TCL Communication Limited

1910-12A, Tower 3, 33 Canton Road, Tsim Sha Tsui,

Kowloon, Hong Kong, China (72) Inventor(s):

Roy Ron Michael Palgy (56) Documents Cited:

WO 2016/182293 A1 WO 2016/178135 A1

WO 2016/159712 A1 WO 2015/140274 A1

US 20160205647 A1 (58) Field of Search:

INT CL H04W

Other: WPI, EPODOC, INTERNET (74) Agent and/or Address for Service:

CMS Cameron McKenna Nabarro Olswang LLP Cannon Place, 78 Cannon Street, London, EC4N 6AF, United Kingdom (54) Title of the Invention: Methods and devices for resource selection for direct transmissions between wireless devices in a wireless communication system

Abstract Title: Selecting direct communication resources in a wireless communication system (57) Methods and apparatus for selecting a resource for direct communications between wireless devices (102,108) via a side link (113) in a wireless communications system. The devices may consist of vehicle user equipment (V-UE), or pedestrian user equipment (P-UE) and the communication may be V2P (vehicle to pedestrian). A first wireless communications device (108), which may be a V-UE, monitors a plurality of resources in a resource pool allocated for use on the side-link during a first time interval. Information relating to the monitored resources is then broadcast to a second wireless communications device (102) which receives the information and selects a resource from the plurality of allocated side link resources based on the received information. The second device may be a P-UE. The broadcast information may contain indications of allocated resources available for selection by the second device which may be transmitted using a Physical Side link Shared Channel (PSSCH).

of 3

FIG. 1 of 3

206

FIG. 2 of 3

305

FIG. 3

Methods and Devices for Resource Selection for Direct Transmissions between Wireless Devices in a Wireless Communication System

Technical Field

Embodiments of the present invention generally relate to wireless communication systems and in particular to devices and methods for resource selection for enabling direct communications between mobile wireless communication devices and is particularly applicable to resource selection by a P-UE (Pedestrian User Equipment) on the so-called PC5 resource pool which is shared with V-UEs (Vehicle User Equipment) or l-UE (Infrastructure User Equipment).

Background

Traditional wireless networks for mobile devices (UEs) rely on a cellular infrastructure which supports UE communications. In these traditional networks, even if communication is between a pair of UEs, communication is managed by network nodes. Here uplink (UL) and downlink (DL) transmissions are always made between a UE and a network node (an eNB/eNodeB for example). As an alternative to communication between UEs via network nodes, direct communication uses a direct link between UEs. Here, the only role of the network nodes, if any, is to establish the direct link and to assign resources. 3GPP LTE (Long Term Evolution) Release 13 considers this type of non-centralised communication, where the term ‘sidelink’ is used to refer to direct links between UEs. A direct link between a pair of UEs is facilitated by the so-called 'PC5' interface at each UE.

For direct communication between UEs there are two types of resource pool: the scheduling assignment (SA) pool, also referred to as the sidelink control pool, and the data pool. Messages are transmitted via the SA pool in order to indicate a transmission of data in the data pool. The data pool is for the transmission of data. Each resource pool is made up of a number of resources, or Physical Resource Blocks (PRB) and subframes. Each data transmission is associated with a SA transmission which informs the receiving UE of the data parameters. The receiving UE is required to blindly decode the control transmission and, then, decode the data.

Each UE operates in a half-duplex mode, where each UE cannot receive and transmit on the same sub-frame. Therefore, for each SA period where the UE is transmitting, the UE cannot receive the SA and data transmissions occurring on the same sub-frame. Here the term “SA period” refers to the period over which resources allocated in a cell for which SA transmissions occur.

-2There are two modes for selecting resources for use by the transmitting UE: Mode 1 and Mode 2. In Mode 1 the SA and data resources are allocated by the network node. In this case, the UE sends a request to the network node over the Uu link, and the network node replies with a grant allocation using specific Downlink Control Information (DCI). Thus, Mode 1 is a contention free way of allocating resources.

In Mode 2 the UE allocates resources without any assistance from the network node. For vehicle to vehicle communications, 3GPP (Third Generation Partnership Project) has agreed on an algorithm for resource (re)selection which involves a sensing operation by means of energy measurements or SA decoding. Working assumptions are that V-UE sensing is performed for at least 1000ms which is greater than the lowest TX periodicity assumed, where transmission periodicities typically range from 100ms to 1000ms. For pedestrian to vehicle communications, it is not yet agreed whether to perform only random resource selection or to perform sensing operation during a limited time for P-UEs. A random resource selection represents a contention based way of allocating resources. Therefore, collisions in resource selections are prone to occur. This is a particular problem where there are many UEs and in situations where data traffic is high.

Herein, the term V2X means LTE-based (Long Term Evolution) communications services connecting vehicles, pedestrians and infrastructures: V2V refers to LTEbased communication between vehicles: V2P refers to LTE-based communication between a vehicle and a device carried by an individual (e.g. handheld terminal carried by a pedestrian, cyclist, driver or passenger): V2I refers to LTE-based communication between a vehicle and a roadside unit. A roadside unit may be implemented in an eNB or static UE (User Equipment).

In the aspect of providing road safety, communications between P-UEs and V-UEs is essential to prevent potential accidents. A pedestrian retrieving a V2P (Vehicle-toPedestrian) message introduces human time scale latency, which may be too slow and may further distract attention from the road. A vehicle retrieving a P2V (Pedestrian-to-Vehicle) message can react much faster, at machine time scale latency. Therefore P2V (i.e., pedestrian UE transmission and vehicle UE reception) is prioritized over V2P (i.e., vehicle UE transmission and pedestrian UE reception).

It has been identified by the 3GPP (Third Generation Partnership Project) that collision of transmissions is a problem when randomly selecting resources from the pool. As a result, in V2V the 3GPP has introduced a sensing mechanism to mitigate this problem, allowing the vehicle to sense the loading of a channel and identify a least crowded resource. However, such a sensing approach is not optimum for a PUE because it induces significant power consumption. Furthermore, with current V2P schemes, a P-UE already consumes considerable power because it needs to receive V2P messages which are generated every 100ms by at least those vehicles which are in proximity. On the other hand, P2V has the potential to consume less battery power because a P-UE needs to access a channel only once in every 1000ms. However, the exact amount of battery consumption is dependent of the P-UE behaviour in “sensing” to identify a likely resource. If a P-UE was also able to sense

-3the channel to identify which resources are occupied by the other UEs, then P-UE power consumption would increase proportionally to the duration of the sensing operation.

It would be advantageous to provide a means for minimising the collision probability of V2P and P2V communications without a P-UE having to perform a comparatively long sensing operation that degrades the battery life.

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.

According to a first aspect of the present invention there is provided a method for selecting a resource for direct communications between wireless communication devices via a sidelink in a wireless communication system, the method comprising; at a first wireless communication device, during a first time interval, monitoring a plurality of resources in a resource pool allocated for use on the sidelink, broadcasting information relating to the monitored resources, and at a second wireless communication device, receiving the broadcast information, and selecting a resource from the plurality of allocated sidelink resources based on the received broadcast information.

In one embodiment, the broadcast information includes an indication of at least one allocated resource which is available for selection by the second wireless communication device. Such resource or resources may be the most likely ones available for selection.

In another embodiment, the broadcast information comprises a notification of resource pool load and the method further comprises, in the second communication device, monitoring, during a second time interval whose value is determined based on resource pool load, the plurality of allocated resources, and selecting a resource therefrom.

In one example, notifications of resources which may be available for selection may be signalled over a PSSCH (Physical Sidelink Shared Channel). Notifications of resource pool load may be signalled over a PSCCH (Physical Sidelink Control Channel). However, such notifications are not restricted to either of these two particular channels.

In one embodiment, the broadcast information includes an indication of whether or not the resource pool load exceeds a pre-determined threshold.

-4According to a second aspect of the present invention there is provided a first wireless communication device including a receiver for, during a first time interval, monitoring a plurality of resources in a resource pool allocated for use on a sidelink in a wireless communication system, a signal processor for determining information relating to the monitored resources, and a transmitter for broadcasting said information for reception by a second wireless communication device in the wireless communication system.

According to a third aspect of the present invention there is provided a second wireless communication device including a receiver for receiving from a first wireless communication device in a wireless communication system, broadcast information relating to a plurality of resources in a resource pool allocated for use on a sidelink and which have been monitored by the first wireless communication device, and signal processing circuitry for selecting a resource from the plurality of allocated resources based on the received broadcast information.

The signal processing circuitry may be arranged to determine a value for a second time interval based on resource pool load and wherein the receiver of the second wireless communication device may be arranged to monitor, during the second time interval, the plurality of resources and select a resource from the plurality of resources based on the monitoring.

The signal processing circuitry may also be adapted to adjust the value of the second time interval based on external factors. Such external factors may include the location of the second wireless communication device and the proximity of a wireless communication device from which broadcast information is received.

The wireless communication system may be an LTE system and the sidelink may comprise a PC5 link. The first wireless communication device may be a V-UE or an IUE and the second communication device may be a P-UE. Each UE may include a PC5 interface.

A P-UE may receive suggestions of likely available resources from multiple V-UEs, and then aggregate the received suggestions and select one resource from the aggregated list.

The invention helps in avoiding resource collisions when P-UEs and V-UEs share the same resource pool, while at the same time, saving battery power consumption in the P-UE by minimising P-UE reception time duration (by setting a comparatively small time interval during which a P-UE listens for channel activity). A further benefit is latency reduction as the invention allows for a shorter offset to be selected thereby allowing P-UE transmission almost immediately following a resource selection.

In one example, a V-UE senses the PC5 link for scheduling assignment (SA) resources for a sufficient period of time for the V-UE to learn V2X transmission behaviour and periodicities. From this, a V-UE is able to predict future un-assigned resource allocations and provide such useful information to a P-UE over the sidelink. The P-UE may, alternatively, sense the PC5 link for V2X scheduling assignment (SA)

-5resources for a shorter period of time and identify a resource for selection. Thus, a PUE can have a better view of the most likely available resources while using a small sensing time. Compared to pure random resource selection, both V-UEs and P-UEs resource collisions are reduced.

In other embodiments, a P-UE may take into account further factors when selecting a resource or for setting the duration of its monitoring period. For example, a network node in the wireless communication system, such as an eNB may transmit, for reception by the P-UE additional information regarding loading or availability of resources. In another example, an l-UE may transmit location information to the PUE. In another example, the P-UE may use inputs from on-board sensors, modules or applications to influence its choice of resource selection. For example, if the P-UE is currently indoors or in a pedestrian-only zone, it is most likely that there is no need to interact with a V-UE. As a result, there is no need to listen for the V2X SA resources. On the other hand, if the P-UE is detected to be at risk owing to a sudden change in speed or direction in the vicinity of a road, for example, the P-UE needs to have a reliable and low latency connection to any V-UE in the vicinity and therefore should set an appropriate sensing period.

According to a third aspect of the invention, there is provided a non-transitory computer readable medium having computer readable instructions stored thereon for execution by a processor to perform the method according to the first aspect.

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 is a simplified block diagram of a part of a wireless communication system and operating in accordance with an example embodiment.

Figure 2 is a simplified flowchart illustrating an example of a method carried out by one or more V-UEs for assisting a P-UE to select a resource for sidelink transmissions; and

Figure 3 is a simplified flowchart illustrating an example of a method carried out by a P-UE for selecting a resource for sidelink transmissions.

-6Detailed 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.

Referring now to FIG.1, an example of part of an LTE cellular communication system operating in accordance with embodiments of the invention is illustrated and indicated generally at 100 and comprises an evolved Node B (eNB) 101 which supports an LTE cell. There may be other eNBs (not shown) forming part of the communication system and supporting other associated cells. The eNBs may be connected to other conventional network components (not shown). The eNB 101 may communicate with one or more User Equipments (UEs) and may allocate resources for use by User Equipments for direct communications with each other. A first User Equipment 102 is located within the area of coverage of the eNB 101 and includes a receiver 103, a transmitter 104 a GPS (Global Positioning System) 105 and a signal processing circuit 106 whose function will be described below. The User Equipment 102 also includes a PC interface 108. The first User Equipment 102 Is carried by a pedestrian and will be referred to hereafter as the P-UE . A second UE 108 is located in a vehicle and will be referred to hereafter as the V-UE 108. The VUE is moving with variable speed and may move within the coverage area of the eNB 101. The V-UE 108 is provided with a transmitter 109, receiver 110, PC5 interface 111 and a signal processor 112 whose function will be described below. The P-UE 102 and the V-UE 108 may communicate with each other directly over a side link 113 and with other similar UEs (not shown) in the vicinity.

Direct communications between two UEs and in particular in this example between P-UE 102 and the-UE 108 via the side link 113 are based on two physical channels: the PSSCH (Physical Sidelink Shared Channel) carries actual transport channel data; and the PSCCH (Physical Sidelink Control Channel) carries control information that enables receiving UE to detect and decode data. The LTE communication system 100 supports V2X services and the V-UE 108 transmits V2V and V2P messages with a periodicity dependent on its road speed. Typically, the V-UE 108 transmits one 300 byte message followed by four 190 byte messages with a periodicity ranging from 100 ms to 1 second depending on road speed. The crash avoidance metrics partnership has suggested that vehicles travelling at around 60 km/h should transmit every 300 ms whereas vehicles travelling at slower speeds of around 15 km/h can transmit every 1000 ms. The P-UE 102, travelling at walking speeds, transmits P2V messages typically every 1000 ms. The message size is fixed at 300 bytes.

One option of resource selection on the sidelink is the autonomous resource selection mode where the UE is selecting resources autonomously. In this mode,

-7 before a UE can transmit a message over the sidelink 113 it has to select a resource from one of several resources which have been allocated for use on the sidelink by the eNB 101 for this purpose. Some of these resources may be already being used by other V-UEs in the vicinity. To aid resource selection, the V-UE 108 utilises a sensing-based autonomous resource selection process. As mentioned above, for direct communication between UEs there are two types of resource pool: the scheduling assignment (SA) pool, and the data pool. Messages are transmitted via the SA pool in order to indicate a transmission of data in the data pool. It will be appreciated that in some arrangements, these pools can overlap or act as a single pool. The V-UE 108 can carry out an energy measurement to detect those SA pool resources currently being utilised by other UEs and therefore not available for its own use. The sensing time period during which these energy measurements are made can be relatively long because power consumption in a vehicle mounted UE is not an issue. (For example, a window size of 600 ms should be sufficient to sense transmissions from V-UEs which transmit with a periodicity of up to 600 ms, i.e for vehicles travelling at speeds in excess of around 28 km/h). In order to avoid resource collisions it is preferred that only those resources that are identified by the V-UE 108 that are vacant can be selected. It has also been proposed that a UE signals in SA the predicted time of its next transmission, e.g. 100*K function (for example, K=3 for a transmission in 300 ms, and a maximum value of K=10 to support 100 ms to 1000 ms). From these measurements, the signal processor 112 in the V-UE 108 may determine one or more resources that can be selected and compile a list of such resources for notifying to the P-UE 102. In this way, the P-UE 102 receives assistance from a V-UE to enable it to select good resources and thereby reduce the number of resource collisions which would occur if the P-UE were to perform random, blind selection of resources and reduce battery consumption if the P-UE were to perform its own sensing measurements for a lengthy time period, say 600 to 1000ms. (It will be understood that the terms resource and resources may include a group of Physical Resource Blocks.) Also from the sensing measurements, the signal processor 112 in the V-UE 108 learns V2X SA pool resource behaviour and periodicity and predicts future unassigned allocations. The identities of future unassigned allocations are notified to the P-UE 102 which the P-UE 102 can use to select a resource for its own use. It will be understood that in V2V resource allocation it is agreed that a V-UE identifies the resources that will be occupied and/or collided by other UEs and avoids a colliding resource allocation for its transmission to the PUE 102.

The messages from the V-UE 108 to the P-UE 102 which identify resources which are likely to be unoccupied and therefore can be selected by the P-UE 102 is sent over the side link 113 using the PSSCH. On initially identifying that the resource pool is loaded, V-UE 108 detects if the pool load exceeds a threshold common to all VUEs in the vicinity and if so, the V-UE 108 signals to the P-UE 102 that this is the case over the PSCCH.

- 8The notification can be made by adding a flag bit in the SA. This should not increase the SCI coding rate in a substantial manner. An alternative implementation whereby the V-UE can indicate without adding any bits to the SA message (not changing its content) is by masking the CRC (Cyclic Redundancy Check) used for SCI decoding. The SA message length is preserved. After attachment, the CRC parity bits are scrambled with the corresponding RNTI and the pool load indication mask.

An implementation for sending the identities of the most likely available resources from the V-UE 108 to the P-UE 102 over the PSSCH can involve multiplexing and interleaving a bitstream for the suggested allocations with the TB (transport block), encoded with Reed-Muller or Viterbi with CRC attachment. Advantageously, this provides in-time information as it does not require MAC pausing, which would increase the latency. The effect on the TB coding rate can be kept minimal by design.

At the P-UE 102, on receipt of a list of most likely available resources (as compiled in the V-UE 108) the signal processing circuit 106 in the P-UE 102 can select a suitable resource with the minimum chance of collisions. The P-UE 102 can also receive similar lists from other V-UE is in the vicinity. In choosing a resource, by taking into account the information from one or more lists, the signal processing circuit 106 can take other factors into account. For example resources suggested by V-UEs which are in closer proximity to the P-UE 102 can be given more weight. The proximity of a particular V-UE may be determined by the P-UE 102 based on a RSSI (Received Signal Strength Indicator).

If the P-UE 102 did not receive a notification that the resource pool was loaded and therefore did not receive any suggestions from any V-UEs for likely available resources then the P-UE 102, if it needs to transmit, can default to making a random selection of a resource in a conventional manner. If a V-UE notifies the P-UE 102 that the resource pool is loaded (using the PSCCH), then the P-UE 102 aggregates all suggested resources (given on the PSSCH) and selects between them. Alternatively, if the PSSCH does not support such information, then the P-UE 102 can perform its own sensing measurements (by listening for V2X transmissions) in a similar fashion to the procedure carried out by the V-UE 108 as mentioned above but for a shorter period of time in order to keep battery consumption as low as possible. The sensing time duration can be chosen according to an assessment of how loaded the resource pool is. This may be deduced by the P-UE if it had been previously listening for transmissions. If it had not detected any transmissions at all then it assumes that the pool is empty. An assessment of pool loading may also rely on a sensed transmission density of other UEs. Alternatively, one or more V-UEs may indicate from several options for pool load values, and the pool load value is mapped to recommended sensing time duration for the P-UE. If no transmissions are detected, the lowest pool load is assumed.

-9If the GPS module 105 detects that the P-UE 102 is indoors or in a pedestrian zone then there is no need to interact with a V-UE and so there is no need to transmit any P2V messages. So for as long as the P-UE 102 remains in such a location there is no need to listen for any V2X SA transmissions and battery life can be conserved. If the GPS module 105 detects a sudden change in speed or a movement in a direction towards a busy road of the P-UE 102 for example, the P-UE 102 needs to transmit P2V messages reliably and with a low latency connection. In this case, a comparatively longer sensing time duration is chosen by the signal processing circuit and sensing measurements are performed in order to identify a free resource.

Reference will now be made to the flow charts of Figures 2 and 3 which illustrate example methods for assisting a P-UE to select a resource for sidelink transmissions. Figure 2 relates to actions carried out by one or more V-UEs 108 and Figure 3 relates to actions carried out by a P-UE 102.

In a first method, with reference to Figure 2, at 201, the V-UE monitors V2X transmissions in the resource pool. If, at 202 the monitoring step reveals that the resource pool load does not exceed a pre-determined threshold, then at 203 the VUE broadcasts a message for receipt by the P-UE 102 notifying it that the resource pool is unloaded. Referring now to Figure 3, if at 301, the P-UE receives a notification from the V-UE that the resource pool is unloaded, then at 302, the P-UE attempts a random resource selection from the resource pool.

In a second method, referring to Figure 2, when, at 202, the pool load is detected to exceed the threshold, the V-UE, at 204, sends a notification of pool load to the P-UE. At 301 (see Figure 3), when the P-UE receives notification of pool load, the method progresses to 303 where the P-UE determines if the PSSCH conveys any broadcast suggestions of likely available resources. If no suggestions are received, then at 304, the P-UE determines a monitoring interval value, depending on resource pool load, and at 305, performs a sensing-based resource selection process by monitoring V2X SA transmissions in the resource pool (during the determined interval) to identify a suitable (free) resource with a low probability of collision with other transmissions.

In a third method, referring back to Figure 2, in a case where the resource pool is loaded above the threshold, the V-UE, at 205 identifies the most likely available resources from the resource pool. At 206 the V-UE broadcasts the identities of the most likely available resources for reception by the P-UE. Referring now to Figure 3; at 303, the P-UE detects that the PSSCH conveys broadcast suggestions; (these suggestions of most likely available resources may be provided by several V-UEs) and at 306, selects a resource from the broadcast suggestions.

- 10While the above embodiments have been described with reference to a V-UE which supplies information for assisting a P-UE in selecting a resource, the methods are equally applicable to an l-UE.

The signal processing functionality of the embodiments of the invention 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

- 11between 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 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.

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.

- 12Aspects 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 recognize that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term ‘comprising’ does not exclude the presence of other elements or steps.

Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented by, 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

1. A method for selecting a resource for direct communications between wireless communication devices via a sidelink in a wireless communication system, the method comprising; at a first wireless communication device, during a first time interval, monitoring a plurality of resources in a resource pool allocated for use on the sidelink, broadcasting information relating to the monitored resources, and at a second wireless communication device, receiving the broadcast information, and selecting a resource from the plurality of allocated sidelink resources based on the received broadcast information.

2. The method of claim 1 wherein the broadcast information includes an indication of at least one allocated resource which is available for selection by the second wireless communication device.

3. The method of claim 2 wherein the wireless communication system is an LTE (Long-Term Evolution) system, the side link comprises a PC5 link and the indication of at least one allocated resource is transmitted using a Physical Sidelink Shared Channel by multiplexing and interleaving a bitstream for each identified allocated resource with a transport block.

4. The method of claim 1 wherein the broadcast information comprises an indication of resource pool load and the method further comprises; in the second communication device, monitoring, during a second time interval whose value is determined based on resource pool load, the plurality of allocated resources, and selecting a resource therefrom.

5. The method of claim 1 wherein the broadcast information includes an indication of whether or not the resource pool load exceeds a predetermined threshold.

6. The method of claim 4 or claim 5 wherein the wireless communication system is an LTE (Long-Term Evolution) system and the sidelink comprises a PC5 link and the broadcast information is transmitted using a Physical Sidelink Control Channel by adding a flag bit in a Scheduling Assignment (SA) message

7. The method of claim 4 or claim 5 wherein the wireless communication system is an LTE (Long-Term Evolution) system and the sidelink comprises a PC5 link and the broadcast information is transmitted using

- 14a Physical Sidelink Control Channel by CRC (Cyclic Redundancy Check) masking.

8. A first wireless communication device including a receiver for, during a first time interval, monitoring a plurality of resources in a resource pool allocated for use on a side link in a wireless communication system, a signal processor for determining information relating to the monitored resources, and a transmitter for broadcasting said information for reception by a second wireless communication device in the wireless communication system.

9. The first wireless communication device of claim 8 comprising a V-UE (Vehicle User Equipment) capable of V2X transmission and reception.

10. The first wireless communication device of claim 8 comprising an l-UE (Infrastructure User Equipment) capable of V2X transmission and reception.

11. A second wireless communication device including a receiver for receiving from a first wireless communication device in a wireless communication system broadcast information relating to a plurality of resources in a resource pool allocated for use on a side link and which have been monitored by the first wireless communication device, and signal processing circuitry for selecting a resource from the plurality of allocated resources based on the received broadcast information.

12. The second wireless communication device of claim 11 wherein the received broadcast information comprises a notification of resource pool load and wherein the signal processing circuitry is arranged to determine a value for a second time interval based on resource pool load, and wherein the receiver is arranged to monitor during the second time interval, the plurality of resources and select a resource from the plurality of resources.

13. The second wireless communication device of claim 12 wherein the signal processing circuitry is arranged to adjust the value of the second time interval based on external factors.

14. The second wireless communication device of claim 13 wherein said external factors comprise at least one of: a location of the second

- 15wireless device; a proximity of a wireless communication device from which broadcast information is received

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15. The second wireless communication device of any of claims 11 to 14 comprising a P-UE (Pedestrian User Equipment) capable of V2X transmission and reception.

16. A non-transitory computer readable medium having computer readable

10 instructions stored thereon for execution by a processor to perform the method according to any of claims 1 to 7.

17. The non-transitory computer readable medium of claim 16 comprising at least one from a group consisting of: a hard disk, a CD-ROM, an optical

15 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.

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