WO2013123674A1

WO2013123674A1 - A method, an apparatus and a computer program product for wireless device-to-device network

Info

Publication number: WO2013123674A1
Application number: PCT/CN2012/071586
Authority: WO
Inventors: Chunyan Gao; Haiming Wang; Jing HAN; Pengfei Sun
Original assignee: Renesas Mobile Corporation
Priority date: 2012-02-24
Filing date: 2012-02-24
Publication date: 2013-08-29

Abstract

The invention relates to the radio interface between apparatuses in a device-to-device network and a base station eNB. According to the method, information is sent to the device-to-device network in signalling arranged to establish or maintain a communication session between a second apparatus for wireless communication connected to the device-to- device network and a first apparatus for wireless communication arranged to connect to a base station or a third apparatus, said information being arranged to establish or maintain the communication session between the second apparatus and the base station or the third apparatus.

Description

A METHOD, AN APPARATUS AND A COMPUTER PROGRAM PRODUCT FOR WIRELESS DEVICE-TO-DEVICE NETWORK

FIELD OF THE INVENTION

The invention relates to mobile communication networks. More specifically, the invention relates to the radio interface between an apparatus for wireless communication and a network element or between at least two apparatuses for wireless communication and a network element. The apparatus for wireless communication may act as a relay between the device- to-device network and a cellular network.

BACKGROUND OF THE INVENTION

Long Term Evolution (LTE) was introduced in release 8 of the 3^rd Generation Partnership Project (3GPP) which is a specification for the 3^rd generation mobile communication systems. LTE is a technique for mobile data transmission that aims to increase data transmission rates and decrease delays, among other things. 3GPP release 10 introduced a next version, LTE Advanced, fulfilling the 4^th generation system requirements .

Device-to-Device (D2D) communication is a concept proposal in standardization, one example of which is provided in the 3GPP document RP-110706, "On the need for a 3GPP study on LTE device-to-device discovery and communication" by Qualcomm Incorporated. The device-to-device communication enables short range data intensive peer-to-peer communication within devices such as user equipments and mobile phones. The D2D could be used to improve the resource usage efficiency, to reduce the power consumption at both the eNB and UE side and to offload the traffic from the cellular network. The low transmission power helps also to reduce interference within the cellular network. The D2D also enables new service types in the future cellular networks; proximity-based applications or services such as targeted close range advertising or public safety services .

If there is a large number of devices capable of D2D operation, the current model where the base station eNB fully controls pairing and resource allocation for each device increases the required signalling especially to the eNB, thereby focusing unnecessary service load to a single network element. Moreover, in some cases the device initially has no desired pair to connect for D2D operation and it would like to know all the potential peers nearby. In this case, the eNB may inform that the adjacent devices require accurate position information, which may be unavailable. From this point of view, automatic discovery of other devices is a desirable feature.

A dedicated channel may be used to enable the automatic discovery of other D2D devices. In this channel, some of the devices send a specific signal with a predefined format. Other devices listening to this channel can become aware of the existing transmitters. In this document, the dedicated channel is called discovery channel and the specific signal is called discovery signal. Once an interesting device or devices may have been found after the device discovery, the device can be coordinated with the interested peer to set up a direct link.

A problem for a device configured to be in the D2D mode is a need to access the cellular network for synchronization, DL control signalling/data reception, or UL transmission. The need for DL/UL connectivity and the resource required for DL/UL connectivity to cellular eNB depend on whether other cellular traffic modes are available besides the D2D communication. Some D2D devices may be configured to be in a RRC-idle mode for the cellular during the D2D communication, while other devices remain RRC- connected in the cellular when the D2D is enabled. A device configured to be in a RRC-idle mode during its D2D communication requires a lot of signalling before the actual transmission of data/signalling or the payload may be sent to the eNB . For example, the device must first enter into a connected mode, then acquire an UL synchronization to the eNB and only after that transmit the data or payload. Especially when the device is a MTC device (Machine Type Communications) sending only a small data packet to the eNB with a long data arrival interval, the signalling overhead is too expensive for such operation. As another example, for two user equipments being in the RRC-connected mode in a cellular network during the D2D communication, the capability for connection to the eNB can differ as some devices may be low cost MTC user equipments with a coverage limitation due to the possible low transmission power.

SUMMARY

The invention discloses a method for a wireless device-to-device network. The method comprises sending information to the device-to-device network in signalling arranged to establish or maintain a communication session between a second apparatus for wireless communication connected to the device-to-device network and a first apparatus for wireless communication arranged to connect to a cellular network or to a third apparatus. The information is arranged to establish or maintain the communication session between the second apparatus and the cellular network or the third apparatus. In one embodiment the third apparatus is arranged to operate as a part of a base station in the cellular network. The third apparatus may also be arranged to operate as a part of a user equipment, for example a user equipment operating as a relay between two other user equipments .

In one exemplary embodiment the first apparatus broadcasts a discovery signal comprising information of the status of the first apparatus in the cellular network. According to this example, the discovery signal is the information sent to the device-to-device network, the information comprising the available downlink or uplink connectivity resource.

In one exemplary embodiment the information comprises a list of at least one apparatus within wireless communication range of the first apparatus. As the first apparatus operates as a relay, the list comprises devices within its reach. The first apparatus is able to operate as a relay between the apparatuses or network elements indicated in the list.

In one exemplary embodiment, an apparatus for wireless communication arranged to operate as a part of a base station sends information to the device-to- device network, indicating at least one first apparatus arranged to connect to the device-to-device network and to the base station or by other means to the cellular network.

In one exemplary embodiment, the second apparatus sends to the first apparatus a link setup request comprising information for the first apparatus to establish a relay between the second apparatus and the third apparatus. In one embodiment, the link setup request is triggered as a response to the second apparatus being in an idle mode and the first apparatus comprising a connectivity time value longer than a predetermined value. In one embodiment, the link setup request is triggered as a response to the second apparatus being outside the wireless communication range of the third apparatus and the first apparatus being inside the wireless communication range of the third apparatus. In another embodiment the link setup request is triggered as a response to the second apparatus being in an idle mode and the first apparatus being in an active mode in the cellular network.

In one exemplary embodiment, the method comprises the first apparatus sending to the second apparatus at a predetermined time information about the status of the transmission between the second apparatus, the first apparatus, the third apparatus or the base station. The status information may comprise an acknowledgement of the transmission and/or the amount of data successfully transmitted from the second apparatus to the third apparatus or to the base station. In other words, confirmation signalling is sent between the devices indicating whether the relayed transmission has been successfully transmitted or not. In one embodiment, the first apparatus abandons the transmission from the second apparatus to the base station if the data has not been transmitted in a predetermined time period. In one embodiment, the second apparatus requests a fourth apparatus to transmit a portion of the data not transmitted in a predetermined time period by the first apparatus between the device-to-device network and the base station. In one embodiment, the second apparatus transmits to the base station a portion of the data not transmitted in a predetermined time period. If all data is not successfully transmitted, the second apparatus that requested the relaying may request another apparatus to complete the transmission, send the remaining portion of the data via a fourth apparatus or communicate directly with the base station eNB sending the remaining data directly to the eNB.

The invention also discloses an apparatus for a wireless device-to-device network comprising at least one processor and at least one memory including computer program code, the at least one memory and the computer program code arranged to, with the at least one processor, cause the apparatus at least to perform: sending information to the device-to-device network in signalling arranged to establish or maintain a communication session between a second apparatus for wireless communication connected to the device-to- device network and a first apparatus for wireless communication arranged to connect to a third apparatus for wireless communication, said information being arranged to establish or maintain the communication session between the second apparatus and the third apparatus. The third apparatus is arranged to operate as a part of a base station in a cellular network or as a part of a user equipment.

In one exemplary embodiment, the apparatus is arranged to operate as a part of the first apparatus and broadcast a discovery signal comprising information of the status of the first apparatus in the cellular network. According to an embodiment, the information comprises the available downlink or uplink connectivity resource. In one exemplary embodiment the information comprises a list of at least one apparatus within wireless communication range of the first apparatus .

In one exemplary embodiment, the apparatus is arranged to operate as a part of a base station and sends information to the device-to-device network indicating at least one first apparatus arranged to connect to the device-to-device network and to the base station or to the cellular network.

In one exemplary embodiment, the apparatus is arranged to operate as a part of a second apparatus and sends to the first apparatus a link setup request comprising information for the first apparatus to establish a relay between the second apparatus and the third apparatus. In one embodiment, the link setup request is triggered as a response to the second apparatus being in an idle mode and the first apparatus comprising a connectivity time value longer than a predetermined value. In one embodiment , the link setup request is triggered as a response to the second apparatus being outside the wireless communication range of the third apparatus and the first apparatus being inside the wireless communication range of the third apparatus. In one embodiment, the link setup request is triggered as a response to the second apparatus being in an idle mode and the first apparatus being in an active mode in the cellular network.

In one exemplary embodiment, the apparatus is arranged to operate as a part of the first apparatus and sends at a predetermined time information about the status of the transmission between the second apparatus, the first apparatus or the third apparatus.

In one exemplary embodiment, the apparatus is arranged to operate as a part of the first apparatus and abandon the transmission if the data has not been transmitted in a predetermined time period.

In one exemplary embodiment, the apparatus is arranged to operate as a part of the second apparatus and request a fourth apparatus to transmit a portion of the data not transmitted in a predetermined time period by the first apparatus between the device-to- device network and the cellular network.

In one exemplary embodiment, the apparatus is arranged to operate as a part of the second apparatus and to transmit a portion of the data not transmitted in a predetermined time period.

The invention also discloses a computer program product comprising a computer-readable medium bearing computer program code embodied therein for use with a computer, the computer program code comprising: code for sending information to the device-to-device network in signalling arranged to establish or maintain a communication session between a second apparatus for wireless communication connected to the device-to-device network and a first apparatus for wireless communication arranged to connect to a third apparatus for wireless communication, said information being arranged to establish or maintain the communication session between the second apparatus and the third apparatus. In one exemplary embodiment the code for assigning third apparatus is arranged to operate as a part of a base station in a cellular network and in another as a part of a user equipment.

In one exemplary embodiment, the computer program product comprises code for broadcasting a discovery signal comprising information of the status of the first apparatus in the cellular network, the code being arranged for the first apparatus.

In one exemplary embodiment, the computer program product comprises code for generating the information comprising the available downlink or uplink connectivity resource. In one exemplary embodiment the code for generating the information comprises a list of at least one apparatus within wireless communication range of the first apparatus.

In one exemplary embodiment, the computer program product comprises code for sending information to the device-to-device network indicating at least one first apparatus arranged to connect to the device- to-device network and to the base station, the code being arranged for an apparatus for wireless communication arranged to operate as a part of a base statio .

In one exemplary embodiment, the computer program product comprises code for sending to the first apparatus a link setup request comprising information for the first apparatus to establish a relay between the second apparatus and the third apparatus, the code being arranged for the second apparatus. In one embodiment,. the code comprises triggering the link setup request as a response to the second apparatus being in an idle mode and the first apparatus comprising a connectivity time value longer than a predetermined value, . In one embodiment, the code comprises triggering the link setup request as a response to the second apparatus being outside the wireless communication range of the third apparatus and the first apparatus being inside the wireless communication range of the third apparatus. In one embodiment, the code comprises triggering the link setup request as a response to the second apparatus being in an idle mode, the first apparatus being in an active mode in the cellular network.

In one exemplary embodiment, the computer program product comprises code for the first apparatus sending to the second apparatus at a predetermined time information about the status of the transmission between the second apparatus, the first apparatus or the third apparatus. In one embodiment, the code comprises generating the status information comprising an acknowledgement of the data successfully transmitted from the second apparatus to the third apparatus. In one embodiment, the code comprises generating the status information comprising the amount of data transmitted successfully. In one embodiment, the code comprises abandoning the transmission from the second apparatus to the third apparatus if the data has not been transmitted in a predetermined time period, the code being arranged for the first apparatus. In one embodiment, the code comprises requesting a third apparatus to transmit a portion of the data not transmitted in a predetermined time period by the first apparatus between the device- to-device network and the cellular network, the code being arranged for the second apparatus. In one embodiment, the code comprises transmitting a portion of the data not transmitted in a predetermined time period by the first apparatus between the device-to- device network and the base station, the code being arranged for the second apparatus. The second apparatus sends the remaining portion of the data directly to the third apparatus, to the cellular network or to the base station.

The present invention introduces new signalling that enables the data transmission to the base station with significantly reduced signalling overhead. The invention provides more flexibility for avoiding the interference and improves the resource efficiency .

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this specification, illustrate embodiments of the invention and together with the description help to explain the principles of the invention. In the drawings:

Fig. 1 is a block diagram illustrating the elements according to the invention,

Fig. 2 is a block diagram illustrating transmission paths between the elements,

Fig. 3 is a block diagram illustrating transmission paths between the elements in another embodiment of the invention, and

Fig. 4 is a diagram illustrating the information flow on a time axis. DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

Figure 1 is a block diagram illustrating an apparatus for wireless communication 101 according to an embodiment connected to a mobile communication network. The apparatus 101 comprises at least one controller 110, such as a processor, a memory 120 and a communication interface 130. In one embodiment, the apparatus is a computer chip. Stored in the memory 120 are computer instructions which are adapted to be executed on the processor 110. The communication interface 130 is adapted to receive and send information to and from the processor 110. The apparatus 101 is commonly referred to as a user equipment UE or it may comprise a part of a user equipment. Examples of the user equipment are a mobile phone, a mobile computing device such as PDA, a laptop computer, a USB stick - basically any mobile device with wireless connectivity to a communication network. It may also be a simpler device such as a TC device purposed for machine-to-machine communication or the like. As the apparatus according to the invention is embedded into the user equipment 101, the apparatuses are in this document referred as the first user equipment 101 and the second user equipment 102. The second user equipment 102 may comprise at least the same set of functionalities and apparatuses as the first user equipment 101. The first and the second apparatus are for example user equipments.

The base station 140 comprises at least one controller 141, such as a processor, a memory 142 and a communication interface 143. In one exemplary embodiment, the base station 140 comprises a computer chip executing the f nctionality according to the invention. Stored in the memory 142 are computer instructions which are adapted to be executed on the processor 141. The communication interface 143 is adapted to receive and send information to and from the processor 141. The user equipment 101 is connected to the base station 140, the connection being formed by radio link 151. From the user equipment's 101 perspective,. the base station 140 offers the functionality required to connect to the wireless network. The third apparatus may be either a user equipment or a base station.

The base station 140 is adapted to be a part of a cellular radio access network such as E-UTRAN applying the WCDMA technology or similar networks suitable for high speed data transmission. Such networks are often also referred to as 4G or LTE. The cellular radio access network may also support carrier aggregation comprising LTE and HSPA. The base station 140 illustrated in Figure 1 symbolizes all relevant network elements required to carry out the functionality of the wireless network. One example of the base station 140 is the evolved Node B, eNB . The wireless portion of the network operated by the base station is referred to as a cell; operations referred to be executed by the cell are executed by the base station. The downlink direction DL is defined as from the network 140 to the first user equipment 101, and the uplink direction UL is defined as from the first user equipment 101 to the network 140.

Figure 2 illustrates the transmission paths between the elements. The eNB 150 is a part of the cellular network and maintains the surrounding cell. The eNB 150 is connected by the cellular network to the first user equipment 101. The first user equipment 101 is configured to connect to the second user equipment 102 via the device-to-device network 161. The second user equipment 102 may also comprise the functionality to connect to the cellular network via the eNB 150.

The present invention enables efficient UL connectivity to the cellular network' s base station eNB 150 for a device in D2D mode. One aspect of the invention presents new indication in the broadcast signalling sent by devices for discovery, e.g. the discovery signal. The indication informs the status of the device in the cellular network, wherein different statuses include connected, idle, available DL/UL connectivity resource, or any other status indicating the mode of the radio resource. The broadcast signalling can also be sent by the eNB 150, indicating a list of nearby devices.

The indication in the link setup request signalling between devices is used to show whether the request is for the D2D communication or for the UL relay. Triggering the request for relay at the user equipment occurs for example when there is a need for UL transmission to the eNB 150 but the second user equipment 102 is in the IDLE mode. In the first example, the first user equipment 101 with the connectivity time longer than a threshold is detected via the discovery process. The discovery process utilizes both the discovery signal and the discovery channel. In the second example, the first user equipment 101 with the active mode in the macro network or cellular network is detected via the discovery process.

The signalling between devices confirms a successfully relayed transmission. The confirmation signalling is sent at a predefined time T. It indicates whether the relaying has been successful or not or the amount of data successfully relayed. If all the data has not yet been relayed successfully within the predefined time T, the first user equipment 101, the device relaying, can be configured automatically to give up the relay operation. For the data not relayed successfully within the predefined time T according to the confirmation signalling, the second user equipment 102 which requested for the relaying may request another device to relay the remaining portion of the data to the cellular network. Another alternative for the second user equipment 102 is to communicate directly with the eNB 150,

By using the device detection procedure, for example via listening to discovery signals, a device in the D2D network, or as in the present example the second user equipment 102, knows whether any other devices nearby are still in the RRC-connected mode in the cellular system. Alternatively, the second user equipment 102 is aware of any nearby devices with an available DL/UL connectivity resource to the eNB 150.

If any available UL/DL connectivity resource to the eNB 150 is detected on the first user equipment 101, the second user equipment 102 may request the first user equipment 101 to assist in sending UL data to the eNB 150 by indicating this in the link setup request. After receiving the link setup request, the first user equipment 101 may start setting up a communication session with the second user equipment 102 in order to receive the data to be transferred to the eNB 150.

After all data has been relayed successfully or before the time T expires, the first user equipment 101 confirms the success of the relay process to the second user equipment 102.

Another embodiment of the invention is illustrated in Figure 3. In this example the third apparatus 103 is a user equipment connected to the first apparatus 101 by the device-to-device communication 162. The first apparatus 101 relays the data transmission from the second apparatus 102 to the third apparatus 103. The fourth apparatus 104 is connected to the second apparatus 102 by the device- to-device communication 163 and to the third apparatus by the device-to-device communication 164. If all the data to be transmitted via the first apparatus 101 has not been successfully relayed in a predetermined time period, the second apparatus 102 may request the fourth apparatus 104 to relay the remaining portion to the third apparatus 103. In this context the third apparatus may be either a user equipment 103 or the base station 150.

The procedure is further illustrated in Figure 4 which describes the UL relayed UL transmission for the user equipment in a D2D mode. The first user equipment 101 and the second user equipment 101 are illustrated in a timing diagram. Figure 4 applies the following denotations: 301 is the time for DL/UL connectivity to cellular eNB, 302 is the discovery signal sent by the first user equipment 101 , 303 is the link setup message for second user equipment 101 , 304 is the link setup request sent by the second user equipment 101 where a relay request indication is sent, 305 is the D2D communication between the first user equipment 101 and the second user equipment 101 and 306 is the first user equipment 101 relaying the data of second user equipment 101 to eNB during its UL connectivity time. The first user equipment 101 is capable of cellular and D2D communication. It maintains its RRC-connected mode, for example still transmitting other cellular traffic besides the D2D operation. The first user equipment 101 has assigned a lot of resources for DL/UL connectivity to eNB 150. The second user equipment 102 is configured to the RRC-idle mode, only monitoring the eNB 150 infrequently and not maintaining the UL synchronization. The second user equipment 102 needs to send data or control signalling to the eNB 150, yet sending this directly to the eNB 150 would require a lot of signalling. For example, the second user equipment 102 must first wait and send data to RACH, Random Access Channel, in order to set up the communication session. In message 3 the second user equipment 102 would send the initial connection setup request and exchange messages with the eNB 150 for the RRC connection setup. The required signalling is very expensive for the purpose, especially when the data packet to be transmitted is small and occasional.

According to the present invention, the second device detects a nearby DL/UL capable device using device detection or discovery. For example, when the first user equipment 101 is found and all the conditions are met, the second user equipment 102 begins a setup procedure with the first user equipment 101 to establish the data relay connection.

Embodiments of the present invention may be implemented in software, hardware, application logic or a combination of software, hardware and application logic. In an example embodiment, the application logic, software or instruction set is maintained on any one of various conventional computer-readable media. In the context of this document, a "computer-readable medium" may be any media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer. A computer-readable medium may comprise a computer-readable storage medium that may be any media or means that can contain or store the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer. The exemplary embodiments can store information relating to various processes described herein. This information can be stored in one or more memories, such as a hard disk, optical disk, magneto-optical disk, RAM, and the like. One or more databases can store the information used to implement the exemplary embodiments of the present inventions. The databases can be organized using data structures (e.g., records, tables, arrays, fields, graphs, trees, lists, and the like) included in one or more memories or storage devices listed herein. The processes described with respect to the exemplary embodiments can include appropriate data structures for storing data collected and/or generated by the processes of the devices and subsystems of the exemplary embodiments in one or more databases.

All or a portion of the exemplary embodiments can be conveniently implemented using one or more general purpose processors, microprocessors, digital signal processors, micro-controllers, and the like, programmed according to the teachings of the exemplary embodiments of the present inventions, as will be appreciated by those skilled in the computer and/or software art(s) . Appropriate software can be readily prepared by programmers of ordinary skill based on the teachings of the exemplary embodiments, as will be appreciated by those skilled in the software art. In addition, the exemplary embodiments can be implemented by the preparation of application-specific integrated circuits or by interconnecting an appropriate network of conventional component circuits, as will be appreciated by those skilled in the electrical art(s). Thus, the exemplary embodiments are not limited to any specific combination of hardware and/or software.

If desired, the different functions discussed herein may be performed in a different order and/or concurrently with each other.

Furthermore, if desired, one or more of the above-described functions may be optional or may be combined. Although various aspects of the invention are set out in the independent claims, other aspects of the invention comprise other combinations of features from the described embodiments and/or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims.

It is obvious to a person skilled in the art that with the advancement of technology, the basic idea of the invention may be implemented in various ways. The invention and its embodiments are thus not limited to the examples described above; instead they may vary within the scope of the claims.

Claims

WHAT IS CLAIMED IS:

1. A method for a wireless device-to-device network, ch a r a c t e r i z e d by:

sending information to the device-to-device network in signalling arranged to establish or maintain a communication session between a second apparatus for wireless communication connected to the device-to-device network and a first apparatus for wireless communication arranged to connect to a third apparatus for wireless communication,

said information being arranged to establish or maintain the communication session between the second apparatus and the third apparatus.

2. The method according to claim 1, ch a r a c t e r i z e d by the third apparatus being arranged to operate as a part of a base station in a cellular network.

3. The method according to claim 2, ch a r a ct e r i z e d by the first apparatus broadcasting a discovery signal comprising information of the status of the first apparatus in the cellular network .

4. The method according to claim 2, c h a r a c t e r i z e d by the information comprising an available downlink or uplink connectivity resource.

5. The method according to claim 1, c ha ra c t e r i z e d by the third apparatus being arranged to operate as a part of a user equipment.

6. The method according to claim 1, c h a r a c t e r i z e d by the information comprising a list of at least one apparatus within wireless communication range of the first apparatus.

7. The method according to claim 2, c h a r a c t e r i z e d by the base station sending information to the device-to-device network indicating at least one first apparatus arranged to connect to the device-to-device network and to the base station.

8. The method according to claim 1, ch a r a ct e r i z e d by the second apparatus sending to the first apparatus a link setup request comprising information for the first apparatus to establish a relay between the second apparatus and the third apparatus .

9. The method according to claim 8, ch a r a c t e r i z e d by triggering the link setup request as a response to the second apparatus being in an idle mode and the first apparatus comprising a connectivity time value longer than a predetermined value.

10. The method according to claim 8, c h a r a c t e r i z e d by triggering the link setup request as a response to the second apparatus being outside the wireless communication range of the third apparatus and the first apparatus being inside the wireless communication range of the third apparatus.

11. The method according to claim 8, c h a r a c t e r i z e d by triggering the link setup request as a response to the second apparatus being in an idle mode and the first apparatus being in an active mode in the cellular network.

12. The method according to claim 1, c h a r a c t e r i z e d by the first apparatus sending to the second apparatus at a predetermined time information about the status of the transmission between the second apparatus, the first apparatus or the third apparatus.

13. The method according to claim 12, c h a r a c t e r i z e d by the status information comprising an acknowledgement of the data successfully transmitted from the second apparatus to the third apparatus .

14. The method according to claim 13, c h a r a c t e r i z e d by the status information comprising the amount of data successfully transmitted from the second apparatus to the third apparatus.

15. The method according to claim 12, c h a r a c t e r i z e d by the first apparatus abandoning the transmission from the second apparatus to the third apparatus if the data has not been transmitted in a predetermined time period.

16. The method according to claim 12, c h a r a c t e r i z e d by the second apparatus requesting a fourth apparatus to transmit a portion of the data not transmitted in a predetermined time period by the first apparatus between the device-to- device network and the third apparatus.

17. The method according to claim 12, c h a r a c t e r i z e d by the second apparatus transmitting to the third apparatus a portion of the data not transmitted in a predetermined time period.

18. An apparatus for a wireless device-to- device network comprising at least one processor and at least one memory including computer program code, the at least one memory and the computer program code arranged to, with the at least one processor, cause the apparatus at least to perform: sending information to the device-to-device network in signalling arranged to establish or maintain a communication session between a second apparatus for wireless communication connected to the device-to-device network and a first apparatus for wireless communication arranged to connect to a third apparatus for wireless communication,

19. The apparatus according to claim 18, c h a r a c t e r i z e d by the third apparatus being arranged to operate as a part of a base station in a cellular network.

20. The apparatus according to claim 19, c h a r a c t e r i z e d by being arranged to operate as a part of the first apparatus and broadcasting a discovery signal comprising information of the status of the first apparatus in the cellular network.

21. The apparatus according to claim 19, c h a r a c t e r i z e d by the information comprising an available downlink or uplink connectivity resource.

22. The apparatus according to claim 18, c h a r a c t e r i z e d by the third apparatus being arranged to operate as a part of a user equipment.

23. The apparatus according to claim 18, ch a r a c t e r i z e d by the information comprising a list of at least one apparatus within wireless communication range of the first apparatus.

24. The apparatus according to claim 19, c h a ra c t e r i z e d by being arranged to operate as a part of the base station and sending information to the device-to-device network indicating at least one first apparatus arranged to connect to the device-to- device network and to the base station.

25. The apparatus according to claim 18, c h a r a c t e r i z e d by being arranged to operate as a part of the second apparatus and sending to the first apparatus a link setup request comprising information for the first apparatus to establish a relay between the second apparatus and the third apparatus .

26. The apparatus according to claim 25, c h a r a c t e r i z e d by triggering the link setup request as a response to the second apparatus being in an idle mode and the first apparatus comprising a connectivity time value longer than a predetermined value .

27. The apparatus according to claim 25, c h a ra c t e r i z e d by triggering the link setup request as a response to the second apparatus being outside the wireless communication range of the third apparatus and the first apparatus being inside the wireless communication range of the third apparatus.

28. The apparatus according to claim 25, c h a r a c t e r i z e d by triggering the link setup request as a response to the second apparatus being in an idle mode and the first apparatus being in an active mode in the cellular network.

29. The apparatus according to claim 18, c h a ra c t e r i z e d by being arranged to operate as a part of the first apparatus and sending to the second apparatus at a predetermined time information about the status of the transmission between the second apparatus, the first apparatus or the third apparatus .

30. The apparatus according to claim 29, c h a r a c t e r i z e d by the status information comprising an acknowledgement of the data successfully transmitted from the second apparatus to the third apparatus .

31. The apparatus according to claim 30, c h a ra c t e r i z e d by the status information comprising the amount of data successfully transmitted from the second apparatus to the third apparatus .

32. The apparatus according to claim 29, ch a r a c t e r i z e d by being arranged to operate as a part of the first apparatus and abandoning the transmission from the second apparatus to the base station if the data has not been transmitted in a predetermined time period.

33. The apparatus according to claim 29, c ha r a c t e r i z e d by being arranged to operate as a part of the second apparatus and requesting a fourth apparatus to transmit a portion of the data not transmitted in a predetermined time period by the first apparatus between the device-to-device network and the third apparatus.

34. The apparatus according to claim 29, c h a r a c t e r i z e d by being arranged to operate as a part of the second apparatus and transmitting to the third apparatus a portion of the data not transmitted in a predetermined time period.

35. A computer program product comprising a computer-readable medium bearing computer program code embodied therein for use with a computer, the computer program code comprising:

code for sending information to the device- to-device network in signalling arranged to establish or maintain a communication session between a second apparatus for wireless communication connected to the device-to-device network and a first apparatus for wireless communication arranged to connect to a third apparatus for wireless communication,

36. The computer program product according to claim 35, c h a r a c t e r i z ed by the code for assigning third apparatus being arranged to operate as a part of a base station in a cellular network.

37. The computer program product according to claim 36, cha r a c t e r i z ed by the code for broadcasting a discovery signal comprising information of the status of the first apparatus in the cellular network, the code being arranged for the first apparatus.

38. The computer program product according to claim 36, c h a r a c t e r i z e d by the code for generating the information comprising an available downlink or uplink connectivity resource.

39. The computer program product according to claim 35, c h a r a c t e r i z e d by the code for assigning the third apparatus being arranged to operate as a part of a user equipment.

40. The computer program product according to claim 35, c h a r a c t e r i z e d by the code for generating the information comprising a list of at least one apparatus within wireless communication range of the first apparatus.

41. The computer program product according to claim 36, ch a r a c t e r i z e d by the code for sending information to the device-to-device network indicating at least one first apparatus arranged to connect to the device-to-device network and to the base station, the code being arranged for an apparatus for wireless communication arranged to operate as a part of a base station.

42. The computer program product according to claim 35, c h a r a ct e r i z e d by the code for sending to the first apparatus a link setup request comprising information for the first apparatus to establish a relay between the second apparatus and the third apparatus, the code being arranged for the second apparatus.

43. The computer program product according to claim 42, c h a r a c t e r i z e d by the code for triggering the link setup request as a response to the second apparatus being in an idle mode and the first apparatus comprising a connectivity time value longer than a predetermined value.

44. The computer program product according to claim 42, c h a r a c t e r i z e d by the code for triggering the link setup request as a response to the second apparatus being outside the wireless communication range of the third apparatus and the first apparatus being inside the wireless communication range of the third apparatus.

45. The computer program product according to claim 42, c h a r a c t e r i z e d by the code for triggering the link setup request as a response to the second apparatus being in an idle mode and the first apparatus being in an active mode in the cellular network .

46. The computer program product according to claim 35, c h a r a c t e r i z e d by the code for the first apparatus sending to the second apparatus at a predetermined time information about the status of the transmission between the second apparatus, the first apparatus or the third apparatus.

47. The computer program product according to claim 46, c h a r a c t e r i z e d by the code for generating the status information comprising an acknowledgement of the data successfully transmitted from the second apparatus to the third apparatus.

48. The computer program product according to claim 47, c h a r a ct e r i z e d by the code for generating the status information comprising the amount of data successfully transmitted from the second apparatus to the third apparatus.

49. The computer program product according to claim 46, c ha r a c t e r i z e d by the code for abandoning the transmission from the second apparatus to the third apparatus if the data has not been transmitted in a predetermined time period, the code being arranged for the first apparatus.

50. The computer program product according to claim 46, ch a r a c t e r i z e d by the code for requesting a third apparatus to transmit a portion of the data not transmitted in a predetermined time period by the first apparatus between the device-to- device network and the base station, the code being arranged for the second apparatus.

51. The computer program product according to claim 46, c h a r a c t e r i z e d by the code for transmitting to the third apparatus a portion of the data not transmitted in a predetermined time period, the code being arranged for the second apparatus.