Method and apparatus of wireless communications

1. A method of sending a request for uplink sounding in a wireless communication system comprising:

communicating, from a base station to a remote terminal, the request on a physical layer downlink control channel signal comprising a first group of information elements each carrying information, corresponding to different states, relevant for scheduling a physical layer uplink shared channel, the uplink shared channel intended for payload data transmission and comprising payload data transmission space and demodulation reference signals space; and

communicating from the remote terminal, after the request is received, to the base station, using sounding reference signals on the uplink shared channel in the demodulation reference signals space,

wherein the sending the request is represented by at least one state of at least one information element from a second group of information elements that is a subset of the first group of information elements, said second group of information elements comprising information elements which are reserved for scheduling-information concerning contents of an exclusive payload data transmission space, wherein said at least one state is undefined for scheduling-information concerning contents of said exclusive payload data transmission space.

2. The method according to claim 1 , wherein at least one information element, which is a member of said first group but not of said second group of information elements, is reserved to provide common scheduling-information which is common for uplink sounding and for payload data transmission on the uplink shared channel.

3. The method according to claim 2 , wherein said common scheduling information is uplink shared channel resource allocation and/or demodulation reference signal allocation for the remote terminal.

4. The method according to claim 1 , comprising communicating the sounding reference signals on the uplink shared channel with a zero-payload in the payload data transmission space.

5. The method according to claim 1 , wherein the at least one state is at least one state of a single information element.

6. The method according to claim 5 , wherein the at least one state is at least one state of Carrier Indicator Field, CIF, information element.

7. The method according to claim 5 , wherein the at least one state is at least one state of Precoder Matrix Index-Rank Index, PMI/RI, information element.

8. The method according to claim 1 , wherein the at least one state is at least two states from a combination of at least two information elements.

9. The method according to claim 8 , wherein the at least two states are states from a combination of Modulation and Coding Selection, MCS, and New Data Indicator, NDI, information elements.

10. The method according to claim 8 , wherein the at least two states are states from a combination of Rank Index, RI, and Modulation and Coding Selection, MCS, information elements.

11. The method according to claim 8 , wherein the at least two states are states from a combination of Precoder Matrix Index-Rank Index, PMI/RI, and Modulation and Coding Selection, MCS, information elements.

12. The method according to claim 1 , wherein the remote terminal is a User Equipment or a Relay Node.

13. A remote terminal of a wireless communication system, the remote terminal comprising

receiving processing circuitry to receive a request for uplink sounding, the request being sent on a physical layer downlink control channel signal comprising a first group of information elements each carrying information, corresponding to different states, relevant for scheduling a physical layer uplink shared channel, the uplink shared channel intended for payload data transmission and comprising payload data transmission space and demodulation reference signals space, and

detection processing circuitry to detect a request represented by at least one state of at least one information element from a second group of information elements that is a subset of the first group of information elements, said second group of information elements comprising information elements which are reserved for scheduling-information concerning contents of an exclusive payload data transmission space, wherein said at least one state is at least one state that is undefined for scheduling-information concerning contents of said exclusive payload data transmission space.

14. The remote terminal according to claim 13 comprising

sending processing circuitry to send, in response to the request, sounding reference signals on the uplink shared channel in the demodulation reference signals space.

15. A radio base station of a wireless communication system, the base station comprising

sending processing circuitry to send a request for uplink sounding on a physical layer downlink control channel signal, the signal comprising a first group of information elements each carrying information, corresponding to different states, relevant for scheduling a physical layer uplink shared channel, the uplink shared channel intended for payload data transmission and comprising payload data transmission space and demodulation reference signals space, and

encoding processing circuitry to encode the request to be represented by at least one state of at least one information element from a second group of information elements that is a subset of the first group of information elements, said second group of information elements comprising information elements which are reserved for scheduling-information concerning contents of an exclusive payload data transmission space, wherein said at least one state is at least one state classified as undefined for scheduling-information concerning contents of said exclusive payload data transmission space.

16. The radio base station according to claim 15 further comprising

receiving processing circuitry to receive, in response to the request, sounding reference signals on the uplink shared channel in the demodulation reference signals space.