Multi-hop relaying in a mobile communication network

1. A client device for transmitting a relay request, the client device comprising:

at least one receiver;

at least one transmitter; and

at least one processor configured to:

use the at least one transmitter to transmit a relay request to a relay device, the relay request comprising a first device identifier identifying the client device and one or more first link identifiers identifying one or more links, at least one of the one or more links linking a further device with a network node via the client device,

use the at least one receiver to receive an acceptance message accepting the relay request from the relay device, and

use the at least one transmitter to transmit data associated with the one or more links to the relay device in dependence on receipt of the acceptance message.

2. The client device as claimed in claim 1 , wherein the at least one processor is further configured to associate an identifier of the relay device with each of the one or more first link identifiers in link entries stored in a memory.

3. A relay device for receiving a relay request, the relay device comprising:

at least one receiver;

at least one transmitter; and

at least one processor configured to:

use the at least one receiver to receive a relay request from a client device, the relay request comprising a first device identifier identifying the client device and one or more first link identifiers identifying one or more links, at least one of the one or more links linking a further device with a network node via the client device,

determine whether the relay request can be accepted,

associate the first device identifier with each of the one or more first link identifiers in link entries stored in a memory, and

use the at least one transmitter to transmit an acceptance message accepting the relay request to the client device upon determining that the relay request can be accepted.

4. The relay device as claimed in claim 3 , wherein the at least one processor is further configured to:

use the at least one receiver to receive data comprising an individual link identifier,

determine a device identifier associated with the individual link identifier from the link entries stored in the memory, and

use the at least one transmitter to transmit the data to a device which identifies with the determined device identifier.

5. The relay device as claimed in claim 3 wherein the at least one processor is further configured to determine whether the relay request can be accepted by using the received one or more first link identifiers and the link entries stored in the memory to determine whether a relaying loop would be established if the relay request would be accepted.

6. The relay device as claimed in claim 5 , wherein the at least one processor is further configured to determine that the relay request cannot be accepted if at least one of the received one or more first link identifiers is associated with information indicating that a link identified by the link identifier ends at the relay device.

7. The relay device as claimed in claim 6 , wherein the at least one processor is further configured to transmit one or more second relay requests to a second relay device and/or a mobile communication network, the one or more second relay requests comprising a second device identifier identifying the relay device and one or more second link identifiers, the one or more second link identifiers comprising at least one of the received one or more first link identifiers.

8. The relay device as claimed in claim 7 , wherein the at least one processor is further configured to indicate in one or more of the link entries that a relay request is pending, the one or more link entries being associated with the one or more second link identifiers.

9. The relay device as claimed in claim 8 , wherein the at least one processor is further configured to:

use the at least one receiver to receive a third relay request from the client device or a further client device, the third relay request comprising a third device identifier and one or more third link identifiers, and

determine that the relay request cannot be accepted if at least one of the third link identifiers is indicated as having a pending relay request.

10. The relay device as claimed in claim 3 , wherein the at least one processor is further configured to:

determine whether at least one of the first link identifiers is not included in the link entries stored in the memory, and

transmit one or more second relay requests to a second relay device and/or a mobile communication network if at least one of the first link identifiers is not included in the link entries, the one or more second relay requests comprising a second device identifier identifying the relay device and the at least one first link identifier.

11. The relay device as claimed in claim 10 , wherein the at least one processor is further configured to associate one or more of the first link identifiers which are included in the link entries with the first device identifier without transmitting a relay request which comprises the one or more first link identifiers included in the link entries.

12. A method of transmitting a relay request, the method comprising:

transmitting a relay request to a relay device, the relay request comprising a first device identifier identifying the client device and one or more first link identifiers identifying one or more links, at least one of the one or more links linking a further device with a network node via the client device;

receiving an acceptance message accepting the relay request from the relay device; and

transmitting data associated with the one or more links to the relay device in dependence on receipt of the acceptance message.

13. A method of receiving a relay request, the method comprising:

receiving a relay request from a client device, the relay request comprising a first device identifier identifying the client device and one or more first link identifiers identifying one or more links, at least one of the one or more links linking a further device with a network node via the client device;

determining whether the relay request can be accepted;

associating the first device identifier with each of the one or more first link identifiers in link entries; and

transmitting an acceptance message accepting the relay request to the client device upon determining that the relay request can be accepted.

14. The method as claimed in claim 13 , further comprising:

receiving data comprising an individual link identifier;

determining a device identifier associated with the individual link identifier from the link entries; and

transmitting the data to a device which identifies with the determined device identifier.

15. A non-transitory computer-readable medium having instructions stored thereon that, when executed by one or more processer of a client device, cause the client device to carry out operations including:

transmitting a relay request to a relay device, the relay request comprising a first device identifier identifying the client device and one or more first link identifiers identifying one or more links, at least one of the one or more links linking a further device with a network node via the client device;

receiving an acceptance message accepting the relay request from the relay device; and

transmitting data associated with the one or more links to the relay device in dependence on receipt of the acceptance message.

16. A non-transitory computer-readable medium having instructions stored thereon that, when executed by one or more processer of a relay device, cause the relay device to carry out operations including: receiving a relay request from a client device, the relay request comprising a first device identifier identifying the client device and one or more first link identifiers identifying one or more links, at least one of the one or more links linking a further device with a network node via the client device; determining whether the relay request can be accepted; associating the first device identifier with each of the one or more first link identifiers in link entries; and transmitting an acceptance message accepting the relay request to the client device upon determining that the relay request can be accepted.