WO2017078598A1

WO2017078598A1 - Network node, wireless device and methods therein for handling radio resources

Info

Publication number: WO2017078598A1
Application number: PCT/SE2016/051074
Authority: WO
Inventors: Marco BELLESCHI; Mats Folke; Yunxi LI
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2015-11-06
Filing date: 2016-11-02
Publication date: 2017-05-11

Abstract

A network node (300), a wireless device (302) and methods therein, for handling radio resources to be used for transmissions from the wireless device (302). When receiving (3:3) from the wireless device (302) a request for radio resources to be used for Device-to-Device, D2D, transmissions to several destinations, the network node (300) defines (3:4) multiple grant groups for the destinations. The network node (300) also performs (3:5) resource allocation for the grant groups and returns (3:6) two or more grants associated to the grant groups for a certain transmission period. The grants indicate which radio resources the wireless device 302 is allowed to use for the D2D transmissions. The wireless device (302) then transmits (3:7) data to the respective selected destinations, using the radio resources that were indicated in the grants for corresponding grant groups.

Description

NETWORK NODE, WIRELESS DEVICE AND METHODS THEREIN FOR

HANDLING RADIO RESOURCES

Technical field

The present disclosure relates generally to a network node, a wireless device and methods therein, for handling radio resources to be used for transmissions from the wireless device.

Background

For some years, different types of radio networks for wireless communication have been developed to provide radio access for various wireless devices. The radio networks are constantly improved to provide better coverage and capacity and to meet the demands from subscribers using increasingly advanced services and equipment, e.g. smartphones and tablets, which may require considerable amounts of bandwidth and resources for data transport in the networks. A limiting factor for capacity of a radio network is the amount of available radio resources, e.g. in terms of time, frequency bandwidth and transmit power, and the capacity of a radio network is improved by more efficient usage of such radio resources.

In this disclosure, the term "wireless device" is used to represent any

communication entity capable of radio communication with a radio network by sending and receiving radio signals, such as e.g. mobile telephones, tablets, laptop computers and Machine-to-Machine, M2M, devices, also known as

Machine Type Communication, MTC, devices. Another common generic term in this field is "User Equipment, UE" which is frequently used herein as a synonym for wireless device.

Further, the term "network node", is used herein to represent any node of a radio network that is operative to communicate radio signals with wireless devices, or to control some network entity having radio equipment for receiving/transmitting the radio signals. The network node in this disclosure could also be referred to as a base station, radio node, e-NodeB, eNB, NB, base transceiver station, access point, etc., depending on the type of network and terminology used. The term eNB is frequently used herein as a synonym for network node. Summary

It is an object of embodiments described herein to address at least some of the problems and issues outlined above. It is possible to achieve this object and others by using a network node, a wireless device and methods therein as defined in the attached independent claims.

According to one aspect, a method is performed by a network node for handling radio resources to be used for transmissions from a wireless device. In this method the network node receives from the wireless device a request for radio resources to be used for Device-to-Device, D2D, transmissions directed to multiple destinations. The network node then defines several grant groups where each grant group allows for transmission to a destination of the received request, and sends to the wireless device two or more grants for a transmission period where each grant is associated to one of the grant groups and indicates radio resources the wireless device is allowed to use for transmission to a destination during the transmission period.

According to another aspect, a network node is arranged to handle radio resources to be used for transmissions from a wireless device. The network node is configured to receive from the wireless device a request for radio resources to be used for D2D transmissions directed to multiple destinations. This functionality may be realized by means of a receiving module in the network node.

The network node is also configured to define several grant groups where each grant group allows for transmission to a destination of the received request, which functionality may be realized by means of a defining module in the network node. The network node is further configured to send to the wireless device two or more grants for a transmission period where each grant is associated to one of the grant groups and indicates radio resources the wireless device is allowed to use for transmission to a destination during the transmission period. This functionality may be realized by means of a sending module in the network node.

According to another aspect, a method is performed by a wireless device for handling radio resources to be used for transmissions from the wireless device. In this method, the wireless device sends to a network node a request for radio resources to be used for D2D transmissions directed to multiple destinations. In response thereto, the wireless device receives from the network node two or more grants for a transmission period where each grant is associated to one of several grant groups, each grant group allowing for transmission to a destination of the request, and each grant indicates radio resources the wireless device is allowed to use for transmission to a destination during said transmission period. The wireless device then transmits data to said destinations on the radio resources that were indicated in the grants for corresponding grant groups. According to another aspect, a wireless device is arranged to handle radio resources to be used for transmissions from the wireless device. The wireless device is configured to send to a network node a request for radio resources to be used for D2D transmissions directed to multiple destinations. This functionality may be realized by means of a sending module in the wireless device. The wireless device is also configured to receive from the network node two or more grants for a transmission period where each grant is associated to one of several grant groups, each grant group allowing for transmission to a destination of the request, and each grant indicates radio resources the wireless device is allowed to use for transmission to a destination during said transmission period. This functionality may be realized by means of a receiving module in the wireless device. The wireless device is further configured to transmit data to said destinations on the radio resources that were indicated in the grants for corresponding grant groups, which functionality may be realized by means of a transmitting module in the wireless device. The above methods, network node and wireless device may be configured and implemented according to different optional embodiments to accomplish further features and benefits, to be described below.

Brief description of drawings

The solution will now be described in more detail by means of exemplary embodiments and with reference to the accompanying drawings, in which: Fig. 1 is a communication scenario illustrating how a relay node called ProSe UE- to-Network Relay can be used to relay communication between an eNB and a UE that may be out of coverage of the eNB, according to 3GPP Rel-13.

Fig. 2 is a diagram illustrating that a relay device, denoted "Relay UE", transmits to multiple destinations UE A-C during individual Sidelink Control, SC, periods, according to the prior art.

Fig. 3 is a signaling diagram illustrating an example of a procedure when the solution is used, according to some possible embodiments.

Fig. 4 is a flow chart illustrating a procedure in a network node, according to further possible embodiments.

Fig. 5 is a flow chart illustrating a procedure in a wireless device, according to further possible embodiments.

Fig. 6 is a diagram illustrating how grants can be directed to different grant groups in different subframes, according to further possible embodiments. Figs 7A-7D are schematic diagrams illustrating some examples of how a wireless device may use granted resources for transmissions to one or more destinations, according to further possible embodiments.

Fig. 8 is a block diagram illustrating a network node and a wireless device in more detail, according to further possible embodiments. Detailed description

Device-to-device (D2D) communication is a well-known and widely used

component of many existing wireless technologies, including ad hoc and cellular networks. Examples include Bluetooth and several variants of the IEEE 802.1 1 standards suite, such as WiFi Direct. These systems operate in unlicensed spectrum. In this disclosure, D2D communication is frequently interchangeably referred to as "proximity services" (ProSe) or "sidelink" communication, which terms could thus be replaced by D2D communication throughout the following text. Recently, D2D communications as an underlay to cellular networks has been proposed as a means to take advantage of the proximity of communicating devices and at the same time to allow devices to operate in a controlled

interference environment. Typically, it is suggested that such device-to-device communication shares the same spectrum as the cellular system, for example by reserving some of the cellular uplink resources for device-to-device purposes. Allocating dedicated spectrum for device-to-device purposes is a less likely alternative as spectrum is a scarce resource and (dynamic) sharing between the device-to-device services and cellular services is more flexible and provides higher spectrum efficiency.

The transmission type when sending data during D2D communication may be any of the following:

Unicast - a specific UE is the receiver.

Multicast (may also be denoted groupcast) - a group of UEs are receivers. · Broadcast - all UEs are receivers, i.e. any UE that is within transmission range and able to "hear" the data.

Where there is no cellular network communication, data can be sent from one device to another device without prior arrangement, thereby reducing the overhead and increasing the communication capacity, which may be helpful or even crucial in emergency situations. The source device transmits data to one (unicast) or more (multicast/groupcast/broadcast) other devices, without first ensuring that the receiving devices are available and ready to receive the data. Such communication may be used for one-to-one or one-to-many communication, but it is particularly effective for multicast and broadcast transmissions and thus well-suited for broadcast and group communication. The communication may be realized, e.g., via PHY (Physical layer) unicast/multicast/groupcast/broadcast transmissions; If PHY broadcast transmissions are used, the transmissions may still be converted into unicast/groupcast/multicast at higher layers. For example, in the MAC layer, multicast or even unicast addresses may be used. Or, alternatively, if using broadcast on both PHY and MAC, multicast or unicast IP addresses may be used at the IP layer.

One possible way to efficiently support D2D communication of data is to use a scheduling assignment (SA) followed by a data transmission. SAs are control messages used for direct scheduling of D2D communication. SAs are transmitted by the UE that intends to transmit D2D data and they are received by the UEs that are potentially interested in such data. The SAs are transmitted on dedicated radio resources characterized by time and frequency, and are typically a sparse and limited resource. SAs provide useful information that can be used by the receiver, e.g., to correctly decode the D2D data transmission associated to the SA (e.g., the resources for data transmission, the modulation/coding parameters, timing information, identities for the transmitter and/or receiver, etc.). Typically, but not necessarily, SAs are transmitted prior to the actual data transmission, so that a receiver is able to selectively receive data based on the content of the SAs. Data transmissions scheduled by a SA may be referred to as a "transmission pattern". SA is known in the 3GPP standard as "Sidelink control information (SCI)" and the content of the information transmitted in SCI is defined in 3GPP as SCI format 0. The transmission of SCI plus its associated D2D data is known as the "Sidelink Control period", or SC period for short. In 3GPP Rel-12, SCI is transmitted on the Physical Sidelink Control Channel PSCCH, and the D2D Data is transmitted on the Physical Sidelink Shared

Channel PSSCH.

To be able to better coordinate interference, the scheduling of D2D transmissions between UEs can be coordinated by the eNB when the UEs are in network coverage. In the 3GPP standard this is called "Scheduled resource allocation" or

"transmission mode 1 ". In this mode the eNB transmits a "sidelink grant" to the UE over the PDCCH which contains the radio resources the UE is allowed to use for transmission in the next SC period. In Rel-12 of the 3GPP standard, the UE is only allowed to use one sidelink grant transmitted to the UE. If the UE receives a second grant, the first one is deleted, meaning that the second grant overwrites the first grant. In order for the eNB to better assign a correct amount of transmission resources, the UEs are required to send Sidelink Buffer Status Reports, SL BSRs, to the eNB. A similar mechanism exists for coordination of uplink transmissions. The SL BSR contains information about the amount of data currently available for transmission on the sidelink interface. There is also a UE autonomous resource selection scheme, or "transmission mode 2". In this mode the UE by itself selects radio resources from a predefined set of available resources, referred to as a "resource pool", which may either be provided by the network, or be pre-configured in the UE, according to some examples. However, the embodiments herein are directed to transmission mode 1 and not transmission mode 2.

In 3GPP Rel-13, a node called "ProSe UE-to-Network Relay" is introduced for public safety operations. In this description, this relay node will be referred to as a relay device or relay UE for short. The purpose of this node is to relay

communication between the eNB and a UE which may be out of coverage of the eNB which UE can be referred to as a "Remote UE". The ProSe UE-to-Network Relay uses the ordinary LTE interface denoted "Uu" to communicate with the eNB and the interface for sidelink communication denoted PC5 to communicate with the Remote UE. A typical scenario where the ProSe UE-to-Network Relay is employed is illustrated in Fig. 1 . In 3GPP Rel-12, the UE is restricted to transmit to only one "destination" in one SC period, which destination can be a single UE or a group of UEs. If a UE wants to transmit to two or more destinations it must first transmit to one destination during one SC period and then switch and transmit to the other destination(s) during one or more subsequent SC periods. This procedure is illustrated in Fig. 2 where a Relay device, denoted Relay UE, transmits data in six consecutive SC periods 1 -6.

In this example shown in Fig. 2, each SC period is 40 ms. The Relay UE is serving three Remote UEs, denoted UE A, UE B and UE C. According to Rel.12, the relay UE can only transmit to at most one UE in an SC period, meaning that when the remote UEs A-C are served equally, each remote UE can be served every third SC period in the above figure as follows: 1 . The relay node transmits to UE A during SC periods #1 and #4.

2. The relay node transmits to UE B during SC periods #2 and #5.

3. The relay node transmits to UE C during SC periods #3 and #6.

D2D communication in 3GPP is mainly designed for communications by Public Safety organizations, although it can be used for other communications as well. This means that the target service that is mainly addressed is push-to-talk VoIP (Voice over IP), which is basically a service operating similar to a walkie-talkie. This service has typically a requirement for bit rate which is in the range of tens of kilobit/s. However, the requirement for coverage is typically higher, as it is often important to reach as many users as possible. As there is a tradeoff between coverage and bit rate, the D2D communication service in 3GPP is not designed for bitrates higher than roughly 100 kilobit/s.

In 3GPP Rel.12, it not possible to perform ProSe communications towards multiple UEs in the same SC period, or generally transmission period. The term "SC period" or "SA period" is used herein as an example of a transmission period. For instance, in the context of public safety in which typically UE-to-Network relays operate, if there are multiple Remote UEs being served by one Relay device, the limitation of only being able to send data to one Remote UE per SC period may lead to significant delay and/or reduced throughput. Therefore, this behavior might potentially have a non-negligible impact on the public safety operations.

To overcome this issue, it is necessary to enable a UE to transmit to multiple destinations within a single SC period, which is made possible by the

embodiments described herein. For resource allocation when the above-described transmission mode 2 (UE autonomous selection) is used, the UE will select resource by itself from known resource pools. With this resource allocation mode the UE may make multiple selections for each SC period, corresponding to the number of destinations it wants to transmit to.

On the other hand, for resource allocation when using the above-described transmission mode 1 following a scheme scheduled by the network, the UE needs to request resources by sending an SL BSR to the eNB in a conventional manner as described above, and in response thereto the eNB provides an SL grant to assign resources for the transmission to one destination via PDCCH in DCI5. However, there is no mechanism available today that allows identifying, for which specific destination a certain grant is valid, For example, an SL grant received at least 4ms before the starting of the SC period is valid for that SC period for a single destination. As such, the eNB has the possibility to override an SL grant valid for a certain SC period by sending a new SL grant valid for the same SC period. Therefore, since in Rel.12 an SL grant is valid for the next SC period, all the previous SL grants provided before by the eNB are overwritten by the new SL grant.

To support simultaneous transmission to multiple destinations, a mechanism needs to be designed that allows the eNB to grant resources for transmissions from a UE to more than one destination. This can be achieved as follows: When a UE sends a request for radio resources to be used for the transmission of data to more than one destination, the eNB sends multiple grants, e.g. sidelink grants, with each grant corresponding to a specific destination which may be a single wireless device or a group of wireless devices.

For a certain UE, all sidelink grants received are divided into multiple "grant groups" by means of a predefined algorithm. If the UE receives multiple grants belonging to same "grant group", the grants received later will overwrite the previously received grant. On the other hand, a subsequent grant belonging to a different "grant group" than a previous grant cannot overwrite the previous grant.

Although, the embodiments and examples herein are described in terms of a ProSe scenario, these embodiments and examples disclosed hereinafter may also be applicable to other D2D scenarios, such as for example V2X, V2V, V2I, and V2P.

An example of how the solution may be employed is illustrated by a signaling diagram in Fig. 3 where a wireless device 302, which may also be denoted a UE, is being served by a network node 300, which may also be denoted an eNB, over a wireless link 304..

A first action 3:1 illustrates that the wireless device 302 may send a buffer status report to the network node 300 which may indicate how many destinations that have data to be transmitted from the wireless device 302. A next action 3:2 illustrates that the wireless device 302 may select destinations to which it intends to send data. Actions 3.1 and 3:2 may be optional in this procedure.

Another action 3:3 illustrates that the wireless device 302 sends a request for radio resources to be used for Device-to-Device, D2D, transmissions directed to multiple destinations. In a next action 3:4, in response to receiving the above request for radio resources, the network node 300 defines several grant groups where each grant group allows for transmission to a destination of the received request. An action 3:5 further illustrates that the network node 300 performs resource allocation for the grant groups defined in action 3:4. In a next action 3:6, the network node 300 sends to the wireless device 302 two or more grants for a certain transmission period such that each grant is associated to one of the grant groups. The grants sent in this action indicate which radio resources the wireless device 302 is allowed to use for transmission to a destination during the transmission period. A final action 3:7 illustrates that the wireless device 302 transmits data to the respective selected destinations, using the radio resources that were indicated in the grants for corresponding grant groups.

An example of how the solution may be employed will now be described with reference to the flow chart in Fig. 4 and in terms of actions performed by a network node such as the above-described network node 300. Fig. 4 thus illustrates a procedure in the network node for handling radio resources to be used for transmissions from a wireless device, such as the above-described wireless device 302. Some optional example embodiments that could be used in this procedure will also be described. Reference will also be made, without limiting the described features and embodiments, to the example scenario shown in Fig. 3.

A first action 400 illustrates that the network node 300 receives from the wireless device 302 a request for radio resources to be used by the wireless device 302 for D2D transmissions directed to multiple destinations, e.g. including one or more other individual wireless devices and/or one or more groups of wireless devices. This action corresponds to action 3:3 above. In a next action 402, the network node 300 defines several grant groups where each grant group allows for transmission to a destination of the received request. In other words, each grant group is addressed to radio resources that can be used for D2D transmission to any of the multiple destinations in the request for radio resources. This action corresponds to action 3:4 above.

In another action 404, the network node 300 may perform resource allocation, i.e. select radio resources for the grant groups defined in action 402, corresponding to action 3:5 above. A final action 406 illustrates that the network node 300 sends to the wireless device 302, two or more grants for a transmission period where each grant is associated to one of the grant groups and indicates radio resources the wireless device 302 is allowed to use for transmission to a destination during the transmission period, the network node 300 thus sends one grant per each grant group defined in action 402. This action 406 corresponds to action 3:6 above

Thereby, it is an advantage that the network node 300 can rapidly allow the wireless device 302 to perform transmissions of data to multiple destinations with a minimum of delay, which can also provide high or increased data throughput. Another advantage is increased flexibility and accuracy in the grant process since the network node 300 can decide how many grants to send and define the grant groups depending on the destinations in the request for radio resources. Yet another advantage is an added flexibility in that the wireless device 302 is free to decide which radio resources in the grants it will use for transmission to the different destinations, which is an improvement over conventional grants which only allow for one destination per grant, as explained above. Some non-limiting example embodiments that can be used in the above procedure of Fig. 4, will now be described. In one example embodiment, the network node 300 may send a subsequent grant associated to a certain grant group such that the subsequent grant overwrites a previously sent grant only when associated to the same grant group, i.e. when the subsequent grant is associated to the same grant group that the previous grant was associated to. Then the wireless device 302 will transmit data on radio resources indicated by the subsequent grant instead of the previously received grant.

In further example embodiments, each grant group may be identified by means of a predefined algorithm or function, which may be defined as follows. One possible variant of this embodiment may be that the predefined algorithm or function says or indicates that each grant group is identified by a time, such as one or more subframes, when the associated grant was sent to the wireless device 302.

Another possible variant of the above embodiment may be that the predefined algorithm or function says or indicates that each grant group is identified by a carrier or cell used for sending the associated grant to the wireless device 302. In these two variants, the grant groups can be identified implicitly, thus without requiring any extra information bits.

There are several possible ways for the network node 300 to find out when it is motivated and helpful to send multiple grants to the wireless device 302, as follows. In some example embodiments, the network node 300 may decide to send multiple grants to the wireless device 302 based on at least one of the following conditions A-D:

A) The network node 300 receives a buffer status report from the wireless device 302 which indicates that it has data available to multiple destinations. This may be indicated in more than one buffer status report from the wireless device.

B) The network node 300 receives a buffer status report from the wireless device 302 which indicates that one or more buffers in the wireless device 302 are above a threshold value. This may be indicated in more than one buffer status report from the wireless device.

C) The network node 300 receives a buffer status report from the wireless device 302 which indicates that the rate of increase in one or more buffers in the wireless device 302 is above a threshold value. This may be indicated in more than one buffer status report from the wireless device.

D) The wireless device 302 has reported a number of destinations in a

SidelinkUEInformation message which number is above a threshold value.

In either of the above conditions, the network node 300 is able to realize that the wireless device 302 has a need for transmitting data to multiple destinations without too much delay, and that multiple grants for corresponding grant groups would be helpful in this respect.

In another example embodiment, each grant may comprise a first part that indicates a resource for transmission of scheduling assignment and a second part that indicates a resource for transmission of data. In another example

embodiment, the network node 300 may receive an indication from the wireless device 302 which indicates that simultaneous transmissions to multiple

destinations is supported. This information may thus be used by the network node 300 when defining the grant groups as of action 402. In yet another example embodiment, the number of destinations may be indicated in a

SideLinkUEInformation message received from the wireless device 302. This information may likewise be used by the network node 300 when defining the grant groups as of action 402.

Another example of how the solution may be employed will now be described with reference to the flow chart in Fig. 5 and in terms of actions performed by a wireless device such as the above-described wireless device 302. Fig. 5 thus illustrates a procedure in the wireless device for handling radio resources to be used for transmissions from the wireless device. Some optional example embodiments that could be used in this procedure will also be described. Reference will again also be made, without limiting the described features and embodiments, to the example scenario shown in Fig. 3.

A first action 500 illustrates that the wireless device 302 sends to a network node 300 a request for radio resources to be used for D2D transmissions directed to multiple destinations, which corresponds to the above-described actions 3:5 and 400. This request is thus received by the network node 300 in action 400 which is indicated by a dashed arrow. In response thereto, the wireless device 302 receives from the network node 300 two or more grants for a transmission period, in an action 502, where each grant is associated to one of several grant groups, each grant group allowing for transmission to a destination of the request, and each grant indicates radio resources the wireless device 302 is allowed to use for transmission to a destination during said transmission period. This action corresponds to the above-described actions 3:6 and 406. These grants are thus sent by the network node 300 in action 406 which is indicated by another dashed arrow. In another action 504, the wireless device 302 transmits data to said destinations on the radio resources that were indicated in the grants for

corresponding grant groups.

Some non-limiting example embodiments that can be used in the above procedure of Fig. 5, will now also be mentioned. Several of the following embodiments correspond to embodiments that have already been described and explained for the procedure in Fig. 4. In one example embodiment, the wireless device 302 may receive a subsequent grant associated to a certain grant group, as shown in an optional action 506 in Fig. 5. In that case, the subsequent grant will overwrite a previously received grant when associated to the same grant group, as shown in another optional action 508.

In another example embodiment, each grant group may be identified by means of a predefined algorithm or function. If so, another example embodiment, may be that the predefined algorithm or function says or indicates that each grant group is identified by a time, such as one or more subframes, when the associated grant was received from the network node 300. In an alternative embodiment, the predefined algorithm or function may say or indicate that each grant group is identified by a carrier or cell used for receiving the associated grant from the network node 300.

embodiment, the wireless device 302 may transmit an indication to the network node 300 indicating that the wireless device 302 supports simultaneous

transmissions to multiple destinations. In yet another example embodiment, the number of destinations may be indicated in a SideLinkUEInformation message transmitted by the wireless device 302 to the network node 300.

There are several advantages that can be achieved when using one or more of the embodiments herein. For example, the physical layer procedure will be not impacted when implementing the above procedures. It is possible for the eNB to overwrite a previous grant. It is possible to reach several UEs with not too much delay since transmission to multiple destinations within one SC period is supported also for resource allocation mode 1 (eNB scheduled mode).

It is further possible for the UE to judge whether there are grants which the UE has received before, and which belongs to same grant group as any of the grants received at step 502 is associated to. If there is any such "old" grant that is thus overwritten by the new grant, the UE will stop using the radio resources associated with the "old" grant. Further, it is possible for the network node to define grant groups which indicate overlapping radio resources, meaning that one or more radio resources may be indicated by e.g. two grant groups such that an

overlapping radio resource is thus shared by the two grant groups. The embodiments and examples herein are thus applicable to transmission mode 1 where resource allocation is scheduled by the network. The grants mentioned above may refer to sidelink grants. Some further non-limiting potential

implementations and features of the embodiments herein will now be mentioned and described. In the following sections, the terms UE and eNB are used for short as examples of the above-described wireless device 302 and network node 300, respectively.

For a certain UE, all sidelink grants are divided into multiple "grant groups" with some algorithm. If there are multiple grants belonging to same "grant group", the later grant will overwrite the previous one. The grants belonging to different "grant groups" cannot overwrite each other. An example of this is illustrated in Fig. 6.

As shown in Fig. 6, for a certain UE, there are four "grant groups" in this example. The UE receives three grants: #1 , #2 and #3. Grant #3 will overwrite Grant #1 as they belong to same grant group, i.e. the UE should discard Grant #1 once it receives Grant #3.

There can be different algorithms to identify a "grant group". Two possible but non-limiting examples 1 -2 of such an algorithm are described below.

1 ) Each "grant group" may be identified according to the time when the grant was transmitted. One possible way of configuring this algorithm is <Grant group number> =

<subframe number of grant being transmitted> modulo <number of grant groups>. The parameter <subframe number of grant being transmitted> is the position of the grant subframe in the radio frame, the value range can be [0, 10239].

- For example, when the number of grant groups is 10, the grant group number may be defined as equal to the subframe number, within a radio frame with 10 subframes, in which a grant is transmitted, i.e. a grant transmitted in subframe N will belong to grant group N.

2) Each "grant group" may be identified according to the carrier or to the cell where the grant was transmitted. - For example, the grant received on a particular carrier/cell belongs to the same corresponding grant group. - For example, a possible way of configuring this algorithm is <Grant group number> = <subcarrier number of grant being transmitted modulo <number of grant groups>

The algorithm of identifying a "grant group" can be cell specific, or UE specific, or pre-defined in standards.

The algorithm of "grant group" can be provided by the eNB via broadcast signaling, e.g. in a System Information Block, SIB, or by dedicated signaling, e.g. RRC or MAC signaling.

The parameter used to calculate "grant group" can be provided by the UE, e.g. via a SidelinkUEInformation RRC message. For example, the "grant group" may be calculated via <Grant group number> = <subframe number of grant being transmitted> modulo <number of grant groups>; The UE may in this case report to the eNB how many simultaneous transmissions it needs to perform within a transmission period and the eNB may reply with the number of grant groups it supports. If no value is returned it can be assumed that the eNB does not support the use of grant groups, or that the number of grant groups is 1 . The number of grant groups needed for the UE can also be the number of destinations in the destination list of the SidelinkUEInformation message.

Without receiving the indication from the UE, the eNB may conclude that the UE does not support transmission to multiple destinations during one SC period, i.e. there will only be one valid grant for the UE at any time, and a new grant will always overwrite previous grant. However, the latter case is not valid for this solution.

There may also be a trigger or function in the eNB to decide the number of grants to send to the UE. The following list includes some criteria 1 -4 that may be used for deciding to send multiple grants to a UE, which basically correspond to the conditions mentioned above for the procedure of Fig. 4.

1 . The buffer status report indicates data to multiple destinations 2. The Buffer status report shows that the buffers in the UE are over a threshold value.

3. The Buffer status report shows that the rate of increase in the buffers in the UE is above a threshold value. 4. The UE has reported a number of destinations in the

SidelinkUEInformation message over a threshold value.

As also mentioned above, each grant may include two parts of resources in the SC period: a first part containing the resource for SA (i.e. the resources used for SCI format 0 transmission) and a second part containing the resource for data: - When eNB sends multiple grants to a UE: among different grants, SC resources can be same or different; among different grants, data resources can be same or different, or overlapped.

- When UE receives more than grants belong to different grant group, UE may adjust the association between SC resource and data resource, and the corresponding transmission.

Some examples 1 -4 of how the solution described herein may be employed in practice, will now be described with reference to Figs 7A-7D, respectively.

Example 1 :

As shown in Fig. 7A, a UE receives two grants from the eNB. When transmitting to destination #2, UE may decides to use the resources from two grants. Accordingly, the transmission to destination #1 can only use the remaining resources of grant #1 .

Example 2:

As shown in Fig. 7B, a UE receives two grants from the eNB. In this case, the UE decides to use both resources for the transmission to same destination. This can be used to increase the data throughput and/or to reduce the delay of data to a certain destination, in this case destination #1 .

It was mentioned above that two grant groups may indicate the same radio resources which thereby overlap by being shared by the two grant groups. In the following examples 3 and 4, such overlapping radio resources are indicated in two grants as follows.

Example 3:

As shown in Fig. 7C, the eNB sends two grants to the UE, grant #1 indicating resources "SC resource #1 ", "data resource #1 ", "data resource #2" and "data resource #3" and grant #2 indicating resources "SC resource #2", "data resource #1 ", "data resource #2", "data resource #3". Hence, "data resource #1 ", "data resource #2" and "data resource #3" are overlapping resources by being indicated in both grants. In this example the UE uses all resources for the transmission to one destination, in this case destination #1 . As the transmission of the SA is given more resources, this can be used for some critical transmission, e.g. to ensure that the SA is received.

Example 4:

As shown in Fig. 7D, the eNB sends two grants to the UE, grant #1 indicating resources "SC resource #1", "data resource #1 ", "data resource #2" and grant #2 indicating resources "SC resource #1", "data resource #3", "data resource #4". Hence, "SC resource #1 " is an overlapping resource by being indicated in both grants. This can be used to secure the SC being received for some critical transmission.

The above examples may also be used to handle the case when the eNB decides to grant less radio resources than requested by the UE by sending grant #1 , but later on, eNB decides to grant more resources to the UE, by sending grant #2.

As mentioned above it is an advantage that the UE can decide which radio resources in the grants it will use for transmission to different destinations. As shown in the above examples 1 -4, it is possible for the UE to use radio resources of one grant group for transmissions to different destinations. The UE may also use radio resources of more than one grant groups for the transmissions to same destination. The UE may further use SC resources and data resources from different grant groups for the transmissions to same destination.

In the above discussion, the grant group number may identify any of the following information:

1 . A specific destination UE identity in which case the mapping between grant group number and the specific destination UE identity is provided via RRC signaling, e.g. the transmitting UE reports the ProSe UE destination ID and the eNB maps such ProSe UE destination ID to a grant group number.

2. A specific destination UE identity which is selected randomly or according to UE implementation. For example a possible UE implementation could be that a transmitting UE associates a certain grant to a certain destination UE on the basis of the size of the grant and the priority of the destination U E and/or of the packet to be transmitted. Another possibility is that a transmitting UE associates a certain grant to a certain destination UE on the basis of the size of the grant and the estimated channel quality (e.g. RSRP) between transmitting UE and destination UE. 3. A specific priority, e.g. the grant group number with lowest index has to be used to transmit to the highest priority UE or to transmit highest priority packets. In this case for instance the eNB can provide a mapping between grant group number and destination UE or packet priorities. Another alternative is to specify a mapping between grant group number and Prose Per Packet Priorities, PPPPs, that are used in Rel.13 for ProSe

communication prioritization between UE-to-Network Relay and Remote UE.

The above-described identification rules can be extended to associate a certain grant group number to more than one UE. Which UE within the grant group to select can be UE-implementation specific or depending on the UE destination priority, or channel quality between the transmitting UE and the destination UE.

The embodiments described herein may provide a way to signal multiple sidelink grants from an eNB to a UE without changing the physical layer. The core part is the association between a sidelink grant and the subframe it was transmitted in.

The block diagram in Fig. 8 illustrates a detailed but non-limiting example of how a network node 800 and a wireless device 802, respectively, may be structured to bring about the above-described solution and embodiments thereof. In this figure, the network node 800 and a wireless device 802 may be configured to operate according to any of the examples and embodiments of employing the solution as described above, where appropriate, and as follows. Each of the network node 800 and a wireless device 802 is shown to comprise a processor "P", a memory "M" and a communication circuit "C" with suitable equipment for transmitting and receiving messages in the manner described herein. The communication circuit C in each of the network node 800 and a wireless device 802 thus comprises equipment configured for communication with each other using a suitable protocol for the communication depending on the

implementation. The solution is however not limited to any specific types of data or protocols. The network node 800 comprises means, e.g. in the form of modules or the like, configured or arranged to perform at least some of the actions in Figs 3 and 4 in the manner described herein. Further, the wireless device 802 comprises means, e.g. in the form of modules or the like, configured or arranged to perform at least some of the actions in Figs 3 and 5 in the manner described above. These actions and procedures may be performed by means of functional modules in the respective processor P in the network node 800 and the wireless device 802 as follows.

The network node 800 is arranged to handle radio resources to be used for transmissions from a wireless device 802. The network node 800 is configured to receive from the wireless device 802 a request for radio resources to be used for Device-to-Device, D2D, transmissions directed to multiple destinations. This operation may be performed by a receiving module 800A in the network node 800, e.g. as described for action 400. The network node 800 is further configured to define several grant groups where each grant group allows for transmission to a destination of the received request. This operation may be performed by a defining module 800B in the network node 800, e.g. as described for action 402.

The network node 800 is further configured to send to the wireless device 802 two or more grants for a transmission period where each grant is associated to one of the grant groups and indicates radio resources the wireless device 802 is allowed to use for transmission to a destination during the transmission period. This operation may be performed by a sending module 800C in the network node 800, e.g. as described for action 406. The network node 800 may further comprise an allocating module 800D configured to perform allocation of the radio resources.

The wireless device 802 is arranged to handle radio resources to be used for transmissions from the wireless device 802. The wireless device 802 is configured to send to a network node 800 a request for radio resources to be used for Device- to-Device, D2D, transmissions directed to multiple destinations. This sending operation may be performed by a sending module 802A in the wireless device 802, e.g. in the manner described for action 500.

The wireless device 802 is further configured to receive from the network node 800 two or more grants for a transmission period where each grant is associated to one of several grant groups, each grant group allowing for transmission to a destination of the request, and each grant indicates radio resources the wireless device 802 is allowed to use for transmission to a destination during said

transmission period. This receiving operation may be performed by a receiving module 802B, e.g. in the manner described for action 502. The wireless device 802 is also configured to transmit data to said destinations on the radio resources that were indicated in the grants for corresponding grant groups. This operation may be performed by a transmitting module 802C in the wireless device 802, e.g. in the manner described for action 504. It should be noted that Fig. 8 illustrates various functional modules in the network node 800 and the wireless device 802, respectively, and the skilled person is able to implement these functional modules in practice using suitable software and hardware. Thus, the solution is generally not limited to the shown structures of the network node 800 and the wireless device 802, and the functional modules therein may be configured to operate according to any of the features and embodiments described in this disclosure, where appropriate.

The functional modules 800A-D and 802A-C described above can be implemented in the network node 800 and the wireless device 802, respectively, by means of program modules of a respective computer program comprising code means which, when run by the processor P causes the network node 800 and the wireless device 802 to perform the above-described actions and procedures. Each processor P may comprise a single Central Processing Unit (CPU), or could comprise two or more processing units. For example, each processor P may include a general purpose microprocessor, an instruction set processor and/or related chips sets and/or a special purpose microprocessor such as an Application Specific Integrated Circuit (ASIC). Each processor P may also comprise a storage for caching purposes.

Each computer program may be carried by a computer program product in each of the network node 800 and the wireless device 802 in the form of a memory having a computer readable medium and being connected to the processor P. The computer program product or memory M in each of the network node 800 and the wireless device 802 thus comprises a computer readable medium on which the computer program is stored e.g. in the form of computer program modules or the like. For example, the memory M in each node may be a flash memory, a

Random-Access Memory (RAM), a Read-Only Memory (ROM) or an Electrically

Erasable Programmable ROM (EEPROM), and the program modules could in alternative embodiments be distributed on different computer program products in the form of memories within the respective network node 800 and the wireless device 802.

The solution described herein may be implemented in each of the network node 800 and the wireless device 802 by a computer program comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out the actions according to any of the above embodiments, where appropriate. The solution may also be implemented at each of the network node 800 and the wireless device 802 in a carrier containing the above computer program, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium.

While the solution has been described with reference to specific exemplifying embodiments, the description is generally only intended to illustrate the inventive concept and should not be taken as limiting the scope of the solution. For example, the terms "network node", "wireless device", "grant" and "grant group" have been used throughout this disclosure, although any other corresponding entities, functions, and/or parameters could also be used having the features and characteristics described here. The solution is defined by the appended claims.

ABBREVIATIONS

3GPP Third Generation Partnership Project

ASIC Application Specific Integrated Circuit

BSR Buffer Status Report

CPU Central Processing Unit

D2D Device-to-device

DCI5 Downlink Control Information, format 5

EEPROM Electrically Erasable Programmable ROM eNB evolved Node B

IEEE Institute of Electrical and Electronics Engineers

IP Internet Protocol

LTE Long Term Evolution

M2M Machine-to-Machine

MAC Medium Access Control

MTC Machine-type Communication

PC5 The interface between two UEs used for ProSe

PDCCH Physical Downlink Control Channel

PHY Physical layer

PPPP Prose Per Packet Priority

ProSe Proximity-based services

PSCCH Physical Sidelink Control Channel

PSSCH Physical Sidelink Shared Channel

RAM Random Access Memory

ROM Read-only Memory

RRC Radio Resource Control

RSRP Reference Signal Received Power

SA Scheduling Assignment

SC Sidelink Control

SCI Sidelink Control Information SIB System Information Block

SL Sidelink

UE User Equipment

V2I Vehicle-to-lnfrastructure V2P Vehicle-to-Pedestrian

V2V Vehicle-to-Vehicle

V2X Vehicle-to-X

VoIP Voice Over IP

Claims

1 . A method performed by a network node (300) for handling radio resources to be used for transmissions from a wireless device (302), the method comprising: - receiving (3:3, 400) from the wireless device (302) a request for radio resources to be used for Device-to-Device, D2D, transmissions directed to multiple

destinations,

- defining (3:4, 404) several grant groups where each grant group allows for transmission to a destination of the received request, and - sending (3:6, 406) to the wireless device (302) two or more grants for a transmission period where each grant is associated to one of the grant groups and indicates radio resources the wireless device (302) is allowed to use for

transmission to a destination during the transmission period.

2. A method according to claim 1 , wherein the network node (300) sends a subsequent grant associated to a certain grant group, and wherein the subsequent grant overwrites a previously sent grant only when associated to the same grant group.

3. A method according to claim 1 or 2, wherein each grant group is identified by means of a predefined algorithm or function.

4. A method according to claim 3, wherein the predefined algorithm or function says that each grant group is identified by a time, such as one or more subframes, when the associated grant was sent to the wireless device (302).

5. A method according to claim 3, wherein the predefined algorithm or function says that each grant group is identified by a carrier or cell used for sending the associated grant to the wireless device (302).

6. A method according to any of claims 1 -5, wherein the network node (300) decides to send multiple grants to the wireless device (302) based on at least one of:

- a buffer status report from the wireless device (302) indicates data available to multiple destinations,

- a buffer status report from the wireless device (302) indicates that the buffers in the wireless device (302) are above a threshold value,

- a buffer status report from the wireless device (302) indicates that the rate of increase in the buffers in the wireless device (302) is above a threshold value, and

- the wireless device (302) has reported a number of destinations in a

SidelinkUEInformation message over a threshold value.

7. A method according to any of claims 1 -6, wherein each grant comprises a first part that indicates a resource for transmission of scheduling assignment and a second part that indicates a resource for transmission of data.

8. A method according to any of claims 1 -7, wherein the network node (300) receives an indication from the wireless device (302) indicating that simultaneous transmissions to multiple destinations is supported.

9. A method according to any of claims 1 -8, wherein the number of destinations is indicated in a SideLinkUEInformation message received from the wireless device (302).

10. A network node (800) arranged to handle radio resources to be used for transmissions from a wireless device (802), wherein the network node (800) is configured to: - receive (800A) from the wireless device (802) a request for radio resources to be used for Device-to-Device, D2D, transmissions directed to multiple destinations, - define (800B) several grant groups where each grant group allows for transmission to a destination of the received request, and

- send (800C) to the wireless device (802) two or more grants for a transmission period where each grant is associated to one of the grant groups and indicates radio resources the wireless device (802) is allowed to use for transmission to a destination during the transmission period.

1 1 . A network node (800) according to claim 10, wherein the network node (800) is configured to send a subsequent grant associated to a certain grant group, and wherein the subsequent grant overwrites a previously sent grant only when associated to the same grant group.

12. A network node (800) according to claim 10 or 1 1 , wherein each grant group is identified by means of a predefined algorithm or function.

13. A network node (800) according to claim 12, wherein the predefined algorithm or function says that each grant group is identified by a time, such as one or more subframes, when the associated grant was sent to the wireless device (802).

14. A network node (800) according to claim 12, wherein the predefined algorithm or function says that each grant group is identified by a carrier or cell used for sending the associated grant to the wireless device (802).

15. A network node (800) according to any of claims 10-14, wherein the network node (300) is configured to decide to send multiple grants to the wireless device (802) based on at least one of:

- a buffer status report from the wireless device (802) indicates data to multiple destinations, - a buffer status report from the wireless device (802) indicates that the buffers in the wireless device (802) are above a threshold value, - a buffer status report from the wireless device (802) indicates that the rate of increase in the buffers in the wireless device (302) is above a threshold value, and

- the wireless device (802) has reported a number of destinations in a

SidelinkUEInformation message over a threshold value.

16. A network node (800) according to any of claims 10-15, wherein each grant comprises a first part that indicates a resource for transmission of scheduling assignment and a second part that indicates a resource for transmission of data.

17. A network node (800) according to any of claims 10-16, wherein the network node (800) is configured to receive an indication from the wireless device (802) indicating that simultaneous transmissions to multiple destinations is supported.

18. A network node (800) according to any of claims 10-17, wherein the number of destinations is indicated in a SideLinkUEInformation message received from the wireless device (802).

19. A method performed by a wireless device (302) for handling radio resources to be used for transmissions from the wireless device (302), the method comprising:

- sending (3:3, 500) to a network node (300) a request for radio resources to be used for Device-to-Device, D2D, transmissions directed to multiple destinations,

- receiving (3:6, 502) from the network node (300) two or more grants for a transmission period where each grant is associated to one of several grant groups, each grant group allowing for transmission to a destination of the request, and each grant indicates radio resources the wireless device (302) is allowed to use for transmission to a destination during said transmission period, and

- transmitting (3:7, 504) data to said destinations on the radio resources that were indicated in the grants for corresponding grant groups.

20. A method according to claim 19, wherein the wireless device (302) receives (506) a subsequent grant associated to a certain grant group, and wherein the subsequent grant overwrites (508) a previously received grant only when associated to the same grant group such that the wireless device (302) transmits data on radio resources indicated by the subsequent grant instead of the previously received grant.

21 . A method according to claim 19 or 20, wherein each grant group is identified by means of a predefined algorithm or function.

22. A method according to claim 21 , wherein the predefined algorithm or function says that each grant group is identified by a time, such as one or more subframes, when the associated grant was received from the network node (300).

23. A method according to claim 21 , wherein the predefined algorithm or function says that each grant group is identified by a carrier or cell used for receiving the associated grant from the network node (300).

24. A method according to any of claims 19-23, wherein each grant comprises a first part that indicates a resource for transmission of scheduling assignment and a second part that indicates a resource for transmission of data.

25. A method according to any of claims 19-24, wherein the wireless device (302) transmits an indication to the network node (300) indicating that

simultaneous transmissions to multiple destinations is supported.

26. A method according to any of claims 19-25, wherein the number of destinations is indicated in a SideLinkUEInformation message transmitted by the wireless device (302) to the network node (300).

27. A wireless device (802) arranged to handle radio resources to be used for transmissions from the wireless device (802), wherein the wireless device (802) is configured to:

- send (802A) to a network node (800) a request for radio resources to be used for Device-to-Device, D2D, transmissions directed to multiple destinations, - receive (802B) from the network node (800) two or more grants for a

transmission period where each grant is associated to one of several grant groups, each grant group allowing for transmission to a destination of the request, and each grant indicates radio resources the wireless device (802) is allowed to use for transmission to a destination during said transmission period, and

- transmit (802C) data to said destinations on the radio resources that were indicated in the grants for corresponding grant groups.

28. A wireless device (802) according to claim 27, wherein the wireless device (802) is configured to receive a subsequent grant associated to a certain grant group, and wherein the subsequent grant overwrites a previously received grant only when associated to the same grant group, then the wireless device (302) is configured to transmit data on radio resources indicated by the

subsequent grant instead of the previously received grant.

29. A wireless device (802) according to claim 27 or 28, wherein each grant group is identified by means of a predefined algorithm or function.

30. A wireless device (802) according to claim 29, wherein the predefined algorithm or function says that each grant group is identified by a time, such as one or more subframes, when the associated grant was received from the network node (800).

31 . A wireless device (802) according to claim 29, wherein the predefined algorithm or function says that each grant group is identified by a carrier or cell used for receiving the associated grant from the network node (800).

32. A wireless device (802) according to any of claims 27-31 , wherein each grant comprises a first part that indicates a resource for transmission of scheduling assignment and a second part that indicates a resource for transmission of data.

33. A wireless device (802) according to any of claims 27-32, wherein the wireless device (802) is configured to transmit an indication to the network node (800) indicating that simultaneous transmissions to multiple destinations is supported.

34. A wireless device (802) according to any of claims 27-33, wherein the number of destinations is indicated in a SideLinkUEInformation message transmitted by the wireless device (802) to the network node (800).

35. A computer program comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out the method according to any one of claims 1 -9 or 19-26.

36. A carrier containing the computer program of claim 35, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium.

37. A network node (800) arranged to handle radio resources to be used for transmissions from a wireless device (802), the network node (800) comprising:

- a receiving module (800A) configured to receive from the wireless device (802) a request for radio resources to be used for Device-to-Device, D2D, transmissions directed to multiple destinations,

- a defining module (800B) configured to define several grant groups where each grant group allows for transmission to a destination of the received request, and

- a sending module (800C) configured to send to the wireless device (802) two or more grants for a transmission period where each grant is associated to one of the grant groups and indicates radio resources the wireless device (802) is allowed to use for transmission to a destination during the transmission period.

38. A network node (800) according to claim 37, wherein the network node (800) is configured to send a subsequent grant associated to a certain grant group, and wherein the subsequent grant overwrites a previously sent grant only when associated to the same grant group.

39. A network node (800) according to claim 37 or 38, wherein each grant group is identified by means of a predefined algorithm or function.

40. A network node (800) according to claim 39, wherein the predefined algorithm or function says that each grant group is identified by a time, such as one or more subframes, when the associated grant was sent to the wireless device (802).

41 . A network node (800) according to claim 39, wherein the predefined algorithm or function says that each grant group is identified by a carrier or cell used for sending the associated grant to the wireless device (802).

42. A network node (800) according to any of claims 37-41 , wherein the network node (300) is configured to decide to send multiple grants to the wireless device (802) based on at least one of:

- a buffer status report from the wireless device (802) indicates data to multiple destinations, - a buffer status report from the wireless device (802) indicates that the buffers in the wireless device (802) are above a threshold value,

- a buffer status report from the wireless device (802) indicates that the rate of increase in the buffers in the wireless device (802) is above a threshold value, and - the wireless device (802) has reported a number of destinations in a

SidelinkUEInformation message over a threshold value.

43. A network node (800) according to any of claims 37-42, wherein each grant comprises a first part that indicates a resource for transmission of scheduling assignment and a second part that indicates a resource for transmission of data.

44. A network node (800) according to any of claims 37-43, wherein the network node (800) is configured to receive an indication from the wireless device (802) indicating that simultaneous transmissions to multiple destinations is supported.

45. A network node (800) according to any of claims 37-44, wherein the number of destinations is indicated in a SideLinkUEInformation message received from the wireless device (802).

46. A wireless device (802) arranged to handle radio resources to be used for transmissions from the wireless device (802), the wireless device (802) comprising:

- a sending module (802A) configured to send to a network node (800) a request for radio resources to be used for Device-to-Device, D2D, transmissions directed to multiple destinations,

- a receiving module (802B) configured to receive from the network node (800) two or more grants for a transmission period where each grant is associated to one of several grant groups, each grant group allowing for transmission to a destination of the request, and each grant indicates radio resources the wireless device (802) is allowed to use for transmission to a destination during said transmission period, and

- a transmitting module (802C) configured to transmit data to said destinations on the radio resources that were indicated in the grants for corresponding grant groups.

47. A wireless device (802) according to claim 46, wherein the wireless device (802) is configured to receive a subsequent grant associated to a certain grant group, and wherein the subsequent grant overwrites a previously received grant only when associated to the same grant group, then the wireless device (302) is configured to transmit data on radio resources indicated by the

subsequent grant instead of the previously received grant.

48. A wireless device (802) according to claim 46 or 47, wherein each grant group is identified by means of a predefined algorithm or function.

49. A wireless device (802) according to claim 48, wherein the predefined algorithm or function says that each grant group is identified by a time, such as one or more subframes, when the associated grant was received from the network node (800).

50. A wireless device (802) according to claim 48, wherein the predefined algorithm or function says that each grant group is identified by a carrier or cell used for receiving the associated grant from the network node (800).

51 . A wireless device (802) according to any of claims 46-50, wherein each grant comprises a first part that indicates a resource for transmission of scheduling assignment and a second part that indicates a resource for transmission of data.

52. A wireless device (802) according to any of claims 46-51 , wherein the wireless device (802) is configured to transmit an indication to the network node (800) indicating that simultaneous transmissions to multiple destinations is supported.

53. A wireless device (802) according to any of claims 46-52, wherein the number of destinations is indicated in a SideLinkUEInformation message transmitted by the wireless device (802) to the network node (800).

54. A network node (800) arranged to handle radio resources to be used for transmissions from a wireless device (802), the network node (800) comprising a processor (P) and a memory (M) containing instructions executable by the processor whereby the network node (800) is configured to:

- receive (800A) from the wireless device (802) a request for radio resources to be used for Device-to-Device, D2D, transmissions directed to multiple destinations,

- define (800B) several grant groups where each grant group allows for

transmission to a destination of the received request, and

55. A network node (800) according to claim 54, wherein the network node (800) is configured to send a subsequent grant associated to a certain grant group, and wherein the subsequent grant overwrites a previously sent grant only when associated to the same grant group.

56. A network node (800) according to claim 54 or 55, wherein each grant group is identified by means of a predefined algorithm or function.

57. A network node (800) according to claim 56, wherein the predefined algorithm or function says that each grant group is identified by a time, such as one or more subframes, when the associated grant was sent to the wireless device (802).

58. A network node (800) according to claim 56, wherein the predefined algorithm or function says that each grant group is identified by a carrier or cell used for sending the associated grant to the wireless device (802).

59. A network node (800) according to any of claims 54-58, wherein the network node (300) is configured to decide to send multiple grants to the wireless device (802) based on at least one of:

- a buffer status report from the wireless device (802) indicates data to multiple destinations,

- a buffer status report from the wireless device (802) indicates that the buffers in the wireless device (802) are above a threshold value,

- a buffer status report from the wireless device (802) indicates that the rate of increase in the buffers in the wireless device (802) is above a threshold value, and

- the wireless device (802) has reported a number of destinations in a

SidelinkUEInformation message over a threshold value.

60. A network node (800) according to any of claims 54-59, wherein each grant comprises a first part that indicates a resource for transmission of scheduling assignment and a second part that indicates a resource for transmission of data.

61 . A network node (800) according to any of claims 54-60, wherein the network node (800) is configured to receive an indication from the wireless device (802) indicating that simultaneous transmissions to multiple destinations is supported.

62. A network node (800) according to any of claims 54-61 , wherein the number of destinations is indicated in a SideLinkUEInformation message received from the wireless device (802).

63. A wireless device (802) arranged to handle radio resources to be used for transmissions from the wireless device (802), the wireless device (802) comprising a processor (P) and a memory (M) containing instructions executable by the processor, whereby the wireless device (802) is configured to: - send (802A) to a network node (800) a request for radio resources to be used for Device-to-Device, D2D, transmissions directed to multiple destinations,

- receive (802B) from the network node (800) two or more grants for a

64. A wireless device (802) according to claim 63, wherein the wireless device (802) is configured to receive a subsequent grant associated to a certain grant group, and wherein the subsequent grant overwrites a previously received grant only when associated to the same grant group, then the wireless device (302) is configured to transmit data on radio resources indicated by the

subsequent grant instead of the previously received grant.

65. A wireless device (802) according to claim 63 or 64, wherein each grant group is identified by means of a predefined algorithm or function.

66. A wireless device (802) according to claim 65, wherein the predefined algorithm or function says that each grant group is identified by a time, such as one or more subframes, when the associated grant was received from the network node (800).

67. A wireless device (802) according to claim 65, wherein the predefined algorithm or function says that each grant group is identified by a carrier or cell used for receiving the associated grant from the network node (800).

68. A wireless device (802) according to any of claims 63-67, wherein each grant comprises a first part that indicates a resource for transmission of scheduling assignment and a second part that indicates a resource for transmission of data.

69. A wireless device (802) according to any of claims 63-68, wherein the wireless device (802) is configured to transmit an indication to the network node (800) indicating that simultaneous transmissions to multiple destinations is supported.

70. A wireless device (802) according to any of claims 63-69, wherein the number of destinations is indicated in a SideLinkUEInformation message transmitted by the wireless device (802) to the network node (800).