Apparatus and methods for relay-assisted uplink communication
A terminal device is arranged to communicate with a base station via a relay device in a wireless communications system. The terminal device comprises: a transmitter arranged to transmit a first access request message to the base station wherein the access request message comprises one from a set of access preambles that indicate relay device uplink assistance is required; a receiver arranged to receive an access request grant response from the base station; and a control processor operably coupled to the transmitter and receiver and arranged to: process the access request grant response; extract transmit power control information therefrom for transmissions to the relay device; map a first power level indicated in the transmit power control information to a second power level associated with a transmission via the relay device; and generate and transmit a transmission to the relay device at the mapped transmit second power level.
1. A terminal device arranged to communicate with a base station via a relay device in a wireless communications system, the terminal device comprising:
a transmitter arranged to transmit an access request message to the base station wherein the access request message comprises one from a set of access preambles that indicate relay device uplink assistance is required;
a receiver arranged to receive an access request grant response from the base station; and
a control processor operably coupled to the transmitter and receiver and arranged to:
process the access request grant response;
extract transmit power control information therefrom for transmissions to the relay device;
map a first power level indicated in the transmit power control information to a second power level associated with a transmission via the relay device; and
generate and transmit a transmission to the relay device at the mapped transmit second power level.
2. The terminal device of claim 1 wherein the transmitter is arranged to first transmit an access request message to the base station a number of times at an increasing power level; and transmit, upon failure to receive a response to said access request messages, the access request message that comprises one from a set of access preambles that indicate relay device uplink assistance is required to the base station.
3. The terminal device of claim 1 wherein the control processor is arranged to generate and transmit a message-3 transmission to the relay device at the mapped transmit second power level.
4. The terminal device of claim 1 wherein the extracted transmit power control (TPC) information comprises a δ msg2 TPC command indicated in a random access response.
5. The terminal device of claim 4 wherein the δ msg2 command is received in a random access response and mapped to a modified δ msg2 command that is indicative of a message that is to be relayed via the relay device.
6. The terminal device of claim 4 wherein the δ msg2 command is received in a random access response and replaced with a new δ msg2 command that is indicative of a message that is to be relayed via the relay device.
7. The terminal device of claim 4 wherein the control processor receives the access request grant response comprising a power delta value and an uplink grant comprising the δ msg2 command.
8. The terminal device of claim 1 wherein a power level of the transmission to the relay device at the mapped transmit second power level is not based on a determination of pathloss between the relay device and the terminal device.
9. An integrated circuit for a terminal device arranged to communicate with a base station via a relay device in a wireless communications system, the integrated circuit comprising:
a control processor arranged to:
transmit an access request message to the base station wherein the access request message comprises one from a set of access preambles that indicate relay device uplink assistance is required;
receive an access request grant response from the base station;
process the access request grant response and extract therefrom transmit power control information for transmissions to the relay device;
map a first power level indicated in the transmit power control information to a second power level associated with a transmission via the relay device; and
generate and transmit a transmission to the relay device at the mapped transmit second power level.
10. A method for a terminal device arranged to communicate with a base station via a relay device in a wireless communications system, the method comprising:
transmitting an access request message to the base station wherein the access request message comprises one from a set of access preambles that indicate relay device uplink assistance is required;
receiving an access request grant response from the base station;
processing the access request grant response and extract therefrom transmit power control information for transmissions to the relay device;
mapping a first power level indicated in the transmit power control information to a second power level associated with a transmission via the relay device; and
generating and transmitting a transmission to the relay device at the mapped transmit second power level.
11. A non-transitory computer program product comprising executable program code to wirelessly communicate data from a terminal device to a base station via a relay device, the executable program code operable for, when executed at the terminal device, performing the method of claim 10 .
12. A wireless communication system comprising:
at least one terminal device;
at least one base station; and
at least one relay device for supporting communications between the at least one terminal device and the at least one base station,
wherein the at least one terminal device comprises:
a transmitter arranged to transmit an access request message to the base station wherein the access request message comprises one from a set of access preambles that indicate relay device uplink assistance is required;
a receiver arranged to receive an access request grant response from the base station; and
a control processor operably coupled to the transmitter and receiver and arranged to:
process the access request grant response;
extract transmit power control information therefrom for transmissions to the relay device;
map a first power level indicated in the transmit power control information to a second power level associated with a transmission via the relay device; and
generate and transmit a transmission to the relay device at the mapped transmit second power level.
13. A base station arranged to communicate with a terminal device on an uplink channel via a relay device in a wireless communications system, the base station comprising:
a receiver arranged to receive an access request message from the terminal device; and
a control processor operably coupled to the receiver and arranged to:
process the access request message;
extract a relayed control element that indicates relay device uplink assistance was used wherein the relayed control element comprises a power delta from the relay device; and
construct and transmit an access request grant response to the terminal device comprising a mapped transmit power value to be applied by the terminal device in relayed communications.
14. The base station of claim 13 wherein the receiver and control processor are further arranged to receive an access request message from the terminal device direct and construct and transmit an access request grant response to the terminal device comprising a transmit power value to be applied by the terminal device in direct communications; and revert to construct and transmit an access request grant response to the terminal device comprising a mapped transmit power value to be applied by the terminal device in relayed communications upon receiving the access request message that comprises one from a set of access preambles that indicate relay device uplink assistance is required to the base station.
15. The base station of claim 13 wherein the mapped transmit power value comprises a δ msg2 TPC command indicated in a random access response.
16. The base station of claim 13 wherein the control processor constructs and transmits the access request grant response comprising a power delta value and an uplink grant comprising the δ msg2 command.
17. An integrated circuit for a base station arranged to communicate with a terminal device on an uplink channel via a relay device in a wireless communications system, the integrated circuit comprising:
a control processor arranged to:
receive an access request message from the terminal device;
process the first access request message;
extract a relayed control element that indicates relay device uplink assistance was used wherein the relayed control element comprises a power delta from the relay device; and
construct and transmit an access request grant response to the terminal device comprising a mapped transmit power value to be applied by the terminal device in relayed communications.
18. A method for a base station arranged to communicate with a terminal device on an uplink channel via a relay device in a wireless communications system, the method comprising:
receiving an access request message from the terminal device;
processing the access request message;
extracting a relayed control element that indicates relay device uplink assistance was used wherein the relayed control element comprises a power delta from the relay device; and
constructing and transmitting an access request grant response to the terminal device comprising a mapped transmit power value to be applied by the terminal device in relayed communications.
19. A non-transitory computer program product comprising executable program code to wirelessly communicate data from a terminal device to a base station via a relay device, the executable program code operable for, when executed at the base station, performing the method of claim 18 .