GB2554383A

GB2554383A - Methods and apparatus for assisting direct communication between mobile devices

Info

Publication number: GB2554383A
Application number: GB1616199.4A
Authority: GB
Inventors: Toledano Ron
Original assignee: TCL Communication Ltd
Current assignee: TCL Communication Ltd
Priority date: 2016-09-23
Filing date: 2016-09-23
Publication date: 2018-04-04
Anticipated expiration: 2036-09-23
Also published as: GB201616199D0; CN109845368B; GB2554383B; CN109845368A; WO2018054243A1

Abstract

Direct communications (D2D) between two or more wireless communication devices are assisted by configuring at least one of two or more wireless communication devices (also known as User Equipment UE) with information that indicates a set of Sidelink Control periods that are allowed for the wireless communication device to initiate data transmissions over the sidelink towards another wireless communication device and information that indicates Sidelink Control periods (SC) in which a transmission from another wireless communication device can be expected. The information may comprise one or more time domain patterns and the patterns may be represented as an index wherein a relationship between a plurality of indices and a pattern of SC periods is configured in a look up table. The time domain pattern may be associated with a specific wireless communication device or a group of wireless communication devices. The wireless communication device may be configured with a control resource index which is permitted to remain persistent between different transmissions of Scheduling Assignment (SA) messages in different SC periods.

Description

(71) Applicant(s):

TCL Communication Limited

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

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

Ron Toledano (74) Agent and/or Address for Service:

CMS Cameron McKenna Nabarro Olswang LLP Cannon Place, 78 Cannon Street, London, EC4N 6AF, United Kingdom (56) Documents Cited:

US 20160219636 A1 US 20140286284 A1

US 20130258996 A1

3GPP; TS 36.213; V13.2.0; RAN WG1; 30th June 2016; Mobile Competence Centre ; 650, route des Lucioles ; F-06921 Sophia-Antipolis Cedex ; France; Physical layer procedures (Release 13); XP051123472 (58) Field of Search:

INT CL H04W

Other: EPODOC, WPI, XP3GPP (54) Title of the Invention: Methods and apparatus for assisting direct communication between mobile devices Abstract Title: Configuring wireless communication devices with Sidelink Control periods (57) Direct communications (D2D) between two or more wireless communication devices are assisted by configuring at least one of two or more wireless communication devices (also known as User Equipment UE) with information that indicates a set of Sidelink Control periods that are allowed for the wireless communication device to initiate data transmissions over the sidelink towards another wireless communication device and information that indicates Sidelink Control periods (SC) in which a transmission from another wireless communication device can be expected.

The information may comprise one or more time domain patterns and the patterns may be represented as an index wherein a relationship between a plurality of indices and a pattern of SC periods is configured in a look up table. The time domain pattern may be associated with a specific wireless communication device or a group of wireless communication devices.

The wireless communication device may be configured with a control resource index which is permitted to remain persistent between different transmissions of Scheduling Assignment (SA) messages in different SC periods.

FIG. 2

206 of 4 (Μ

FIG. 1 of 4

FIG. 2 of 4

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FIG. 4

- 1 Methods and Apparatus for assisting Direct Communication between Mobile Devices

Technical Field

Embodiments of the present invention generally relate to wireless communication systems and in particular to apparatus and methods for assisting direct communications between mobile wireless communication devices.

Background

Traditional wireless networks for mobile devices or User Equipment (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. That is, uplink (UL) and downlink (DL) transmissions are always made between a UE and a base station (an eNB/eNodeB for example). As an alternative to communication between UEs via network nodes, direct communication (sometimes referred to as D2D) 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.

A part of the so-called ProSe (Proximity Services) feature which evolved in 3GPP LTE (Third Generation Partnership Project, Long Term Evolution) under Release-12 and Release-13, defines a protocol to describe the manner in which two or more UEs which are in proximity with each other will be able to communicate directly with or without some assistance from the base-station. The term ‘sidelink’ is used to refer to direct links between UEs. A direct link between a pair of UEs is facilitated by the socalled 'PC5' interface at each UE.

There are two sidelink transmission modes (TM) defined in a current Release-13 specification for sidelink communication: sidelink TM1 and sidelink TM2. (A late Release-13 which takes into account vehicle to vehicle, V2V, communications also specifies TM 3 and TM 4 modes.) Sidelink TM1 is considered as a networkcontrolled transmission mode where the UE requests sidelink opportunities from the eNB. The eNB can then assign sidelink resources for control and for data transmission based on an eNB specific implementation. Being network-controlled, operating with this transmission mode means that a network can provide dedicated resources for sidelink transmission that are interference free. The disadvantage with this mode however is that it involves signalling overhead and more network coordination effort.

-2With sidelink transmission mode TM2, resource selection for control and data is under the responsibility of the UE itself, with a random selection of resources for each SC (Sidelink Control) period that is intended for transmission. In the current Release 13 specification, for each SC period there is a (random) resource reselection process carried out by the UE, but without maintaining any resources selected in previous SC periods. A SC period is a time window during which D2D communication between devices can occur. The SC period duration and offset is configurable by an eNB and is either broadcast or signalled directly to UEs. A sender UE that may wish to begin a data transmission can then indicate its intention to transmit to a target UE and this intention is allowed to be sent at every SC period, (or when ordered by the eNB in TM1 mode). A UE which is receiving a transmission on the sidelink monitors the sidelink side (for reception) at every SC period.

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.

In current Rel-13 specification, in sidelink TM2 when two UEs are communicating with each other, each UE can initiate a transmission independently and select independent (e.g. also the same/overlapping) control and data resources.

In current Rel-13 specification, in sidelink TM1 and sidelink TM2, in order to transmit a sidelink control message on the PSCCH (Physical Sidelink Control Channel), the control message is always sent twice on the two physical RBs (Resource Blocks) that are mapped by a control resource index.

In current Rel-13 specification, in sidelink TM1 and sidelink TM2, once a UE transmits a sidelink control message, it will also transmit sidelink data (unless dropped due to collision with direct Uplink transmission) and there is no definition of priority such that a UE may transmit a control message but be de-prioritized and drop the data transmission.

With the existing sidelink TM1 and sidelink TM2, it is still possible for two UEs to communicate with each other also when one UE is a wearable device and the other UE is relay device. A wearable device (or remote device) is a power-limited, low cost device, such as a smart watch for example. A relay device is a more capable device which is less power-limited and less sensitive to processing complexity such as a smart phone or home router, for example. However these modes are inefficient

-3and not optimised. One reason for the inefficiency is that both devices are assumed to be awake all the time and listening for sidelink communications constantly. This is because the current design supports public safety applications where broadcast transmissions from other devices are to be expected all the time. This is power inefficient in those cases where broadcast transmissions are not constant or where sidelink transmissions are unicast type rather than broadcast. Furthermore, there is no association between two devices so they do not remember each other and no assumptions are made with regard to their transmission and/or reception configurations.

It would be advantageous to provide a more efficient way of enabling D2D communications.

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 assisting direct communications between two or more wireless communication devices via a sidelink in a wireless communication system, the method comprising; configuring at least one of said two or more wireless communication devices with information that indicates a set of SC (Sidelink Control) periods that are allowed for the wireless communication device to initiate data transmissions over the sidelink towards another wireless communication device and that indicates a set of SC (Sidelink Control) periods during which a transmission from another wireless communication device can be expected.

Said information may comprise one or more time domain patterns.

The wireless communication device may be a UE, a relay device, a smartphone, a smart watch or other wearable, mobile, or remote device.

A transmission opportunity window (tx-pattern) may be defined which indicates allowed sidelink control periods for initiating data transmissions. A reception opportunity window (rx-pattern) may be defined which indicates sidelink control periods allowed for monitoring. The tx-pattern and rx-pattern may be merged into one time domain pattern. The tx-pattern and rx-pattern may overlap.

Some SC periods may not be designated as either transmit periods or monitor periods.

-4A time domain pattern may be represented as an index and a relationship between a plurality of such indices and a pattern of transmit and/or monitor periods (i.e. where transmission is allowed and/or reception can be expected) may be configured in a look up table. The look up table may be configured in or made accessible to each wireless communication device in a group of wireless communication devices.

Alternatively, a time domain pattern may be described by a multiplying factor and an offset value. For example if the multiplying factor is denoted as'm' and the offset as O' then D2D transmission (or reception) on a sidelink is allowed (or expected) at SC period index T if i mod m = o (where mod is a modulo operation).

A time domain pattern or its index or other identifying parameter may be associated with a particular wireless communication device or a group of wireless communication devices. That is to say that a time domain pattern or its index or other identifying parameter may be associated with a sidelink destination identity of a particular wireless communication device, or a group of wireless communication devices. This association may be done by a wireless communication device initially informing a base station of one or more sidelink destination IDs with which it wishes to communicate. In return, the base station may acknowledge (or not) and include the destination ID in the configuration information. Alternatively, a time domain pattern or its index may be configured in a wireless communication device without any such association.

When a time domain pattern relating to transmissions is associated with a sidelink destination identity of another wireless communication device or a group of wireless communication devices, the transmission opportunities which belong to that pattern are reserved for a possible transmission that is intended for that wireless communication device or group of wireless communication devices that are associated with the pattern. Similarly, when a time domain pattern relating to monitoring is associated with a sidelink identity of another wireless communication device or group of wireless communication devices, the reception opportunities which belong to that pattern are provided for the detection of transmissions by that wireless communication device or group of wireless communication devices. When the assigned pattern is without any specific association, a transmitting (or receiving) wireless communication device can use transmission (and/or reception) opportunities identified by the pattern without any restriction with regard to the destination/source sidelink identity.

In one embodiment, a time domain pattern may be transmitted to a wireless communication device by a base station as part of its serving cell configuration. In another embodiment, a time domain pattern may be transmitted to a wireless communication device by another wireless communication device. In a further embodiment, in a self-configuring mode, a time domain pattern may be derived by a wireless communication device from configuration parameters which are broadcast by a base station. As an example, a base station may broadcast a parameter with

-5value p. A wireless communication device which receives the parameter checks the following condition: if mod(SC-period, p) == mod(sidelink identity, p) then the wireless communication device is allowed to transmit/receive where sidelink identity can be the destination/own identity. So if p=3, say, and the wireless communication's identity is 41, for example, then the wireless communication device is expected to monitor SC-period index {2,5,8,11,14,...}.

According to a second aspect of the present invention there is provided a wireless communication device configured with information that indicates a set of SC (Sidelink Control) periods that are allowed for initiation of data transmissions over a sidelink towards another wireless communication device and that indicates a set of SC (Sidelink Control) periods during which a transmission from another wireless communication device can be expected.

Said information may comprise one or more time domain patterns.

The wireless communication device may include a look up table for storing a time domain pattern.

The wireless communication device may also be configured with a control resource index. This may be used for transmission of a Scheduling Assignment (SA) message. The control resource index may be associated with a side link identity of a wireless communication device. In such a case, a wireless communication, when receiving, knows which control resource index to look for and when transmitting, knows which control resource index it has to use for transmission towards a destination wireless communication device or group of wireless communication devices.

The control resource index may be kept persistent between different transmissions without re-selecting a randomly. Further, the same control resource index may be shared between two or more wireless communication devices. In one arrangement, two or more wireless communication devices may share the same control resource index with non-overlapping transmission opportunity. In another arrangement, two or more wireless communication devices may share the same control resource index with overlapping transmission opportunity, this being achieved by sending each SA message over only a single resource block.

In one embodiment, the control resource index is hopped in a pseudorandom manner with a hopping function known to at least two wireless communication devices which are capable of sidelink communication with one another. The pseudorandom function can be calculated by a wireless communication device in order to derive the actual

-6control resource index to be used before each side link control period intended for data transmission. This measure can mitigate inter-cell interference.

In one embodiment, the wireless communication device is configured with a priority value whereby if the wireless communication device and another wireless communication device attempt to initiate a sidelink transmission simultaneously, only the wireless communication device with the higher priority is allowed to transmit data. Hence, in a case where two wireless communication devices share the same control resource index, a priority rule defines a behaviour for each device when both devices transmit a Scheduling Assignment message in the same Sidelink Control period. The higher priority device proceeds with its intended data transmission in that SC period and the lower priority device drops its transmission. Similarly, the higher priority device is also not expected to monitor possible SA transmissions made by a lower priority device (i.e for the SC period when a higher priority device is transmitting).

According to third aspect of the invention, there is provided a base station for transmitting a configuration data to a wireless communication device served by the base station, said configuration data comprising information that indicates a set of SC (Sidelink Control) periods that are allowed for initiation of data transmissions over a sudelink towards another wireless communication device and that indicates a set of SC (Sidelink Control) periods during which a transmission from another wireless communication device can be expected.

Said information may comprise one or more time domain patterns.

The base station may be an eNB.

The invention prevents two UEs initiating a transmission at the beginning of an SC period without considering each other's intentions and provides the following advantages. Collision avoidance between two UEs directly communicating with one another is minimised without having a continuous coordination effort from the network side. This is achieved by having a configuration that can be known to both UE is and a consensus that is known to each UE with regard to when each UE is allowed to transmit data. The invention promotes a lower decoding complexity of the physical control Channel by a receiving UE. This is achievable because the receiving side can be made aware of which control resource index is to be used by a transmitting UE for transmitting a control message. Furthermore, the utilisation of existing side link resources are improved because the network can have a better control on which sidelink resources are being used and at which times. The invention enables a UE to perform sidelink communications even when the resource pool bandwidth is wider than the UE capability. This can be achieved by providing a resource control index advance which avoids the need to monitor control messages when the control channel bandwidth is wider than the UE's bandwidth capability. There is also a greater resilience to inter-cell interference when the same or overlapping resources are assigned for indirect communication in different neighbouring cells. If the control resource index is hopped with different seed in

-7different cells, then the probability of persistent collision along the control channel is reduced. Power efficiency can also be improved. By defining a pattern of transmit/receive according to the data traffic of the UE is involved in D2D communication, a receiving UE does not have to constantly monitor transmissions from a sender UE during those times in which a transmission is not allowed for that particular sender UE.

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 a UE for transmitting a side link control message;

Figure 3 is a simplified flowchart illustrating an example of a method of receiving a side link control message carried out at a UE; and

Figure 4 is a simplified flowchart illustrating an example of a method carried out by a UE for selecting resources for transmission of data.

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.

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), three being shown in Figure 1, 102a, 102b, 102c and may configure the UEs with parameters for assisting direct communications with each other over a sidelink 103. In this example, each UE 102a, 102b, 102c has a look up table 104a, 104b, 104c, respectively which in this is configured by way of configuration data transmitted by the eNB 101. The UEs 102a,

- 8102b, 102c, forma set of UEs within a group of UEs which are capable of D2D communication.

In the system of Figure 1, D2D communications can occur between UEs (102a and 102c over sidelink 103, for example), during periodic time-windows referred to as SC (Sidelink Control) periods. The period duration is configured by the eNB 101, and in this example is signalled directly to each UE 102a, 102b, 102c.The eNB 101 also configures each UE 102a, 102b, 102c with a time-domain pattern that defines the SC periods that allow a (sender) UE to initiate a data transmission towards target UE. A “transmission opportunity window” is defined and denoted herein as tx-pattern.

The eNB 101 also configures each UE 102a, 102b, 102c with a time-domain pattern that defines the SC periods in which a (potential target) UE is expected to monitor a possible data transmission from a sender UE. A “reception opportunity window” is defined and denoted herein as rx-pattern. Monitoring messages by sender UEs, is not required outside this reception opportunity window.

In this example, the tx-pattern and rx-pattern for a UE overlap so that certain SC periods may be used for either transmission or monitoring and others may be used for neither.

In this example, the time domain patterns are configured into the look up tables 104a, 104b, 104c of each respective UE 102a, 102b, 102c. Each look up table defines a sequence of “1”s and “0”s. Each entry in the sequence represents a SC period and the sequences are cyclically repeated over a complete cycle of radio frames. A “1” indicates a period which can be used as a transmission and/or reception opportunity and a “0” indicates that no transmission and/or reception opportunity exists. Each pattern is given an index (k). An example of a look up table is shown in the table below.

Index	Pattern
K	a(k) = a0,a1,a2,a3
0	(1,1,1,1)
1	(0,1,1,1)
2	(0,0,1,1,)
3	(0,0,0,1)
4	(1,0,0,0,)
5	(1,1,0,0,)
6	(1,1,1,0)
7	(0,1,1,0)

When a UE is configured with index 'k' then this relates to a time domain pattern a(k) = a0,a1 ,a2,a3 which defines those SC periods during which transmission or reception

-9opportunities exist, Further, aj = 1 when j = i mod L where aj is the jth entry of a(k), i is a SC period index and L is the pattern length, 'mod' is a modulo operation.

With reference to the above table, L=4 and for index k=2 for a tx-pattern then a(2) = (0,0,1,1) is the pattern to follow and the sequence of SC periods allowed for transmission (starting from a zero-based SC period index) will be 2, 3, 6, 7, 10, 11 and so on.

An example of a method for sending a sidelink control message will now be described with reference to Figure 1 and the flowchart of Figure 2. At 201, the eNB 101 transmits a tx-pattern and rx-pattern to each UE 102a, 102b, 102c. UE 102a desires to send a D2D data transmission to UE 102c. (In other examples, the patterns may be pre-set to default values, e.g. all SC periods may be valid). Sender UE102a obtains a control resource index and this can be done, at 202, by the eNB 101 signalling this control resource index in a Radio Resource Control (RRC) message to UE102a. An alternative method relies on the UE 102a randomly selecting a control resource index per transmission of a control message. The control resource index is an integer with its value mapped to actual time-frequency physical resource(s) intended to carry a Scheduling Assignment (SA) message.

In this example, the eNB 101 also configures the UE 102a so that the control resource index signalled to the UE 102a remains persistent between different transmissions of SA messages in different SC periods at least as long as UE 102a is connected to or camped onto the same cell (served by eNB101). This control resource index is referred to herein as ctrl-index-tx. In other examples, a control resource index is assigned to the UE 102a by another UE or can be implicitly derived based on parameters that are broadcast by the eNB. and/or configured to the UE.

The control resource index ctrl-index-tx is hopped in a pseudo-random manner with a hopping function that is known to both UE102a and UE102c by signalling from the eNB 101 or other base station (not shown). Then only the initialization value and the function have to be known. In this manner, a ctrl-index-tx can be assigned to UE102a in cell A, and the same value can also be assigned to UE102b in cell B. When the same physical resources are configured for sending SA messages in both cells A and B, then if both UE102a and UE102b attempt to initiate communication during the same SC periods, the physical resources will not collide with each other often. The control resource index is calculated between different periods and the pseudorandom function can be based on an expression having the following form:

K(i+1) = (K(i) + f(n)) mod N, where Km is the control resource index during the mth SC period, f(n) is a pseudo-random number function based on PCI and N is the total number of control resource indices in a given resource pool.

The assigned ctrl-index-tx can be associated with a sidelink destination identity of another UE, or a set of UEs, or associated with a tx-pattern, or it can also be

- 10assigned toa UE without any specific association. A UE may be assigned with multiple ctrl-index-tx

UEs can share a same control resource index in a given period. This can be efficient in saving the amount of indices required to support given number of UEs. For example, in a case where both UE102a and UE102c have been configured with a same SC period for a transmission opportunity, they can still share the same assigned control resource index for SA transmission. This is achievable by assigning one of the two physical Resource Blocks, to which a control resource index is mapped, to one UE and the other of the two physical Resource Blocks to the other UE. In this way, each UE transmits an SA message over only a single physical RB rather than over both physical RBs, Each UE knows in advance which of the two physical RBs associated with the assigned control resource index, is allocated to it (and to the other UE).

The UE 102a waits for the next SC period which belongs to its configured tx-pattern. During this period (i.e. a transmission opportunity window), at 203, where initiation of a transmission is allowed, UE102a transmits a control message (i.e the SA message in this example) which is intended for UE102c. The SA message indicates UE102a's intention to transmit (to UE 102c). The SA message typically includes transmissionrelated parameters such as data allocation, MCS (Modulation and Coding Scheme), frequency hopping, etc.

The following illustrates the flow from the perspective of a low priority UE. It is assumed that the UE is not a high priority UE and to avoid a collision of data transmissions where both UE 102a and UE 102c attempt to initiate a transmission in the same SC period, at 204 it is determined whether or not a transmission by a higher priority source has been detected. A priority value can depend on UE type. For example, a UE which declares itself as a remote UE will automatically be deemed to have a higher priority. A UE which declares itself as a relay UE will automatically be deemed to have a lower-priority. A priority value can, alternatively, be provided with upper-layer signalling and in this case is configured specifically to the UE. In a case where a single control resource index is shared (e.g. UE 102a and UE 102c have been assigned the same ctrl-index-tx,) the UE having the earlier occurring time index of the two is deemed to have the higher priority. So if a transmission by a higher priority sender has been detected, then at 205, the transmission is dropped. If not, then at 206, the UE proceeds with transmission of data. In this way the UE with the lower-priority will have enough time to decode this SA message and drop its data transmission before its first opportunity for data transmission becomes available. The UE with the higher priority is not expected to monitor a possible SA message from the lower-priority UE, as it will receive priority in any case, (this being true when the higher priority device transmits). However, it may still monitor the lower-priority SA message based on a specific implementation. In a

- 11case where the UE is assumed to be a high priority UE, the transmission of data can go ahead and step 204 can be skipped.

A method for receiving a sidelink control message will now be described with reference to Figure 1 and the flowchart of Figure 3.

At 301, the eNB 101 transmits a tx-pattern and rx-pattern to each UE 102a, 102b, 102c. In this example, UE 102a is the sender (and operates as described above with reference to Figure 1) and UE 102c is the target. The target UE 102c is made aware of the control resource index that has been assigned to the sender UE 102a. As the this control resource index (referred to herebelow as cntrl-index-rx) is directly mapped to physical resources, this means that the target UE 102c can monitor the physical resources that possibly carry an SA message by the sender UE 102a rather than exhaustively monitoring all possible physical resources. In this example, cntrlindex-rx has a value O'.

So at 302, the eNB 101 transmits a message which assigns UE 102c with cntl-indexrx = 0.

At 303, target UE 102c monitors the sidelink for possible SA messages carrying its own identity only over the physical resource blocks which are mapped by that particular resource control index = 0 rather than monitoring all physical reserve resource blocks mapped by indices, which may typically have values 0 to 15.

At 304, target UE 102c detects the SA message from UE 102a which is associated with the identity of UE 102c and then receives and decodes the following transmitted data sent by the sender UE 102a.

In other embodiments cntrl-index-rx can be associated with a sender identity of another UE or a group of sender UEs. It may also be associated with the rx-pattern or can be assigned to a UE without any specific association. A UE may be assigned with a multiple number of cntrl-index-rx.

As mentioned above, if a UE is shares the same control resource index with another UE and the two UE's are assigned a priority, the lower priority UE is configured to monitor the first resource block instance mapped by the control resource index. The higher priority UE is not expected to monitor the other resource block mapped by this index. If a UE is not assigned with any priority, it is configured to monitor the other resource block mapped by this index as is conventional.

In some cases UE 101a which is a relay, say, may wish to communicate with more than one target UE, say UE 102b and 102c, which are both remote devices, say, in the same SC period. In such cases, UE102a sends two separate SA messages intended for UE102b and UE102cto indicate this intention.

- 12The invention also, optionally, provides a method by which a wireless communication device may select resources for data transmission. Such a method is applicable to the aforementioned case where a relay UE may want to communicate with two or more separate remote UEs in the same SC period. Initially, an eNB provides a timedomain pattern and a control resource index to the UE. However, it is left to the UE to select (at random) frequency resources and subframes which comprise an SC period that is part of the provided time domain pattern to be used for data transmissions.

With reference to Figure 4, at 401, a relay UE randomly selects a first Time Resource Pattern (TRP) i.e a pattern of subframes to be used for data transmission towards a first remote UE in a random manner out of all Time Resource Patterns available. Next, at 402, the UE selects a contiguous set of frequency resources to be used towards the first remote UE in the subframes defined by the TRP selected. At 403, if there is a transmission needed for an additional remote UE, then at 404, the relay UE randomly selects a second TRP out of those TRP patterns available that are orthogonal to any TRP already selected. The process then reverts to 402. When no transmission is needed for any additional remote UE, then at 405 the data is transmitted using the resources selected.

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

- 13media 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 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.

- 14Furthermore, 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 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.

- 15Furthermore, 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 assisting direct communications between two or more wireless communication devices via a sidelink in a wireless communication system, the method comprising; configuring at least one of said two or more wireless communication devices with information that indicates a set of Sidelink Control periods that are allowed for the wireless communication device to initiate data transmissions over the sidelink towards another wireless communication device and that indicates a set of Sidelink Control periods in which a transmission from another wireless communication device can be expected.

2. The method of claim 1 wherein said information comprises one or more time domain patterns.

3. The method of claim 2 comprising representing a time domain pattern as an index wherein a relationship between a plurality of indices and a pattern of SidelLink Control periods is configured in a look up table.

4. The method of either of claims 2 or 3 comprising associating a time domain pattern with a specified wireless communication device.

5. The method of any of claims 2 to 4 comprising associating a time domain pattern with a group of wireless communication devices.

6. The method of either of claims 4 or 5 wherein an association between a time domain pattern and a wireless communication device includes a sidelink destination identity.

7. The method of any preceding claim comprising transmitting said information to a wireless communication device from a base station.

8. The method of any preceding claim comprising configuring a wireless communication device with a control resource index which is permitted to remain persistent between different transmissions of Scheduling Assignment messages in different Sidelink Control periods.

9. The method of any preceding claim comprising configuring two wireless communication devices with the same control index which maps two physical Resource Blocks and further configuring each of said two wireless communication devices to transmit a Scheduling Assignment message over a different one of the two physical Resource Blocks.

- 1710. The method of claim 8 or claim 9 comprising hopping the control resource index in a pseudorandom manner.

11. The method of any of claims 8 to 10 comprising associating the control resource index with an identity of a wireless communication unit.

12. The method of any preceding claim comprising configuring a wireless communication device with a priority value.

13. A wireless communication device configured with information that indicates a set of Sidelink Control periods that are allowed for initiation of data transmissions over a sidelink towards another wireless communication device and that indicates a set of Sidelink Control periods in which a transmission from another wireless communication device can be expected.

14. The wireless communication device of claim 13 wherein said information comprises one or more time domain patterns.

15. The wireless communication device of claim 14 including a look up table for storing a time domain pattern.

16. The wireless communication device of either of claims 14 or 15 and adapted to randomly select a plurality of subframes within a time domain pattern for use for transmission of data.

17. A base station for transmitting configuration data to a wireless communication device served by the base station, said configuration data comprising information that indicates a set of Sidelink Control periods that are allowed for initiation of data transmissions over a sidelink towards another wireless communication device and that indicates a set of Sidelink Control periods in which a transmission from another wireless communication device can be expected.

Intellectual

Property

Office

Application No: GB1616199.4 Examiner: Mr Daniel Davies