Sounding Reference Signal (srs) Usage

1. A method, comprising: incorporating into an uplink grant message for a physical uplink shared channel (PUSCH), by a base station in a communications system, information on whether a last symbol of an uplink subframe that is reserved by the base station in every n th subframe for sounding reference signal (SRS) transmissions, is available for the PUSCH; and transmitting the uplink grant message comprising the information on the last symbol to a user equipment (UE), wherein the user equipment is configured to ignore cell-specific SRS subframe configuration when determining whether the last symbol of the uplink subframe is available for transmission of the PUSCH.

2. The method according to claim 1 , wherein the information comprises a new SRS trigger type.

3. The method according to claim 1 , wherein the incorporating further comprises: incorporating one bit in the uplink grant message to indicate whether the last symbol is available for the PUSCH, and incorporating one bit in the uplink grant message to indicate whether the UE should send an SRS.

4. A method, comprising: incorporating into an uplink grant message by a base station in a communications system, information on whether a last symbol of an uplink subframe for sounding reference signal (SRS) transmissions, is available for a physical uplink shared channel (PUSCH); transmitting the uplink grant message comprising the information on the last symbol to a user equipment (UE); and incorporating one bit in the uplink grant message to indicate whether the last symbol is available for the PUSCH, and incorporating one bit in the uplink grant message to indicate whether the UE should send an SRS, wherein said one bit indicating whether the last symbol is available for the PUSCH and said one bit indicating whether the UE should send an SRS are interpreted jointly according to: ‘00’ indicates to not transmit an SRS, and puncture the PUSCH; ‘01’ indicates to not transmit an SRS, and transmit the PUSCH in the last symbol; ‘10’ indicates to transmit an SRS, and puncture the PUSCH; ‘11’ indicates to transmit an SRS, and transmit the PUSCH.

5. A method, comprising: incorporating into an uplink grant message by a base station in a communications system, information on whether a last symbol of an uplink subframe for sounding reference signal (SRS) transmissions, is available for a physical uplink shared channel (PUSCH); transmitting the uplink grant message comprising the information on the last symbol to a user equipment (UE); and incorporating one bit in the uplink grant message to indicate whether the last symbol is available for the PUSCH, and incorporating one bit in the uplink grant message to indicate whether the UE should send an SRS, wherein a first and a second SRS configuration are provided, and wherein said one bit indicating whether the last symbol is available for the PUSCH and said one bit indicating indicate whether the UE should send an SRS are interpreted jointly according to: ‘00’ indicates to not transmit an SRS, and puncture the PUSCH; ‘01’ indicates to not transmit an SRS, and transmit the PUSCH in the last symbol; ‘10’ indicates to transmit a first SRS configuration, and puncture the PUSCH; ‘11’ indicates to transmit a second SRS configuration, and puncture the PUSCH.

6. The method according to claim 1 , wherein the incorporating further comprises: incorporating two bits in the uplink grant message to indicate whether the last symbol is available for the PUSCH.

7. A method, comprising: incorporating into an uplink grant message by a base station in a communications system, information on whether a last symbol of an uplink subframe for sounding reference signal (SRS) transmissions, is available for a physical uplink shared channel (PUSCH); transmitting the uplink grant message comprising the information on the last symbol to a user equipment (UE); and incorporating two bits in the uplink grant message to indicate whether the last symbol is available for the PUSCH; wherein the two bits in the uplink grant message indicating whether the last symbol is available for the PUSCH are interpreted according to: ‘00’ indicates to puncture the PUSCH in the last symbol; ‘01’ indicates to transmit part of allocated PUSCH physical resource blocks (PRBs); ‘10’ indicates to transmit another part of allocated PUSCH PRBs; ‘11’ indicates to transmit the PUSCH.

8. The method according to claim 2 , wherein a new SRS trigger type has a higher priority than existing SRS trigger types.

9. The method according to claim 1 , further comprising defining a zero-power SRS configuration to allow for flexible muting of the last symbol.

10. The method according to claim 2 , wherein, when use of a new SRS trigger type is configured, hybrid automatic repeat request (HARQ) re-transmissions follow a pre-defined codepoint of the new SRS trigger type or follow puncturing rules defined for an overlapping cell-specific SRS.

11. An apparatus, comprising: at least one processor; and at least one memory comprising computer program code, the at least one memory and the computer program code, with the at least one processor, causing the apparatus at least to incorporate into an uplink grant message for a physical uplink shared channel (PUSCH), information on whether a last symbol of an uplink subframe that is reserved by a base station in every n th subframe for sounding reference signal (SRS) transmissions, is available for the PUSCH; and transmit the uplink grant message comprising the information on the last symbol to a user equipment (UE), wherein the user equipment is configured to ignore cell-specific SRS subframe configuration when determining whether the last symbol of the uplink subframe available for transmission of the PUSCH.

12. The apparatus according to claim 11 , wherein the information comprises a new SRS trigger type.

13. The apparatus according to claim 11 , wherein the at least one memory and the computer program code are further configured, with the at least one processor, to cause the apparatus at least to: incorporate one bit in the uplink grant message to indicate whether the last symbol is available for the PUSCH, and incorporating one bit in the uplink grant message to indicate whether the UE should send an SRS.

14. The apparatus according to claim 13 , wherein said one bit indicating whether the last symbol is available for the PUSCH and said one bit indicating whether the UE should send an SRS are interpreted jointly according to: ‘00’ indicates to not transmit an SRS, and puncture the PUSCH; ‘01’ indicates to not transmit an SRS, and transmit the PUSCH in the last symbol; ‘10’ indicates to transmit an SRS, and puncture the PUSCH; ‘11’ indicates to transmit an SRS, and transmit the PUSCH.

15. The apparatus according to claim 13 , wherein a first and a second SRS configuration are provided, and wherein said one bit indicating whether the last symbol is available for the PUSCH and said one bit indicating indicate whether the UE should send an SRS are interpreted jointly according to: ‘00’ indicates to not transmit an SRS, and puncture the PUSCH; ‘01’ indicates to not transmit an SRS, and transmit the PUSCH in the last symbol; ‘10’ indicates to transmit a first SRS configuration, and puncture the PUSCH; ‘11’ indicates to transmit a second SRS configuration, and puncture the PUSCH.

16. The apparatus according to claim 11 , wherein the at least one memory and the computer program code are further configured, with the at least one processor, to cause the apparatus at least to: incorporate two bits in the uplink grant message to indicate whether the last symbol is available for the PUSCH.

17. The apparatus according to claim 16 , wherein the two bits in the uplink grant message indicating whether the last symbol is available for the PUSCH are interpreted according to: ‘00’ indicates to puncture the PUSCH in the last symbol; ‘01’ indicates to transmit part of allocated PUSCH physical resource blocks (PRBs); ‘10’ indicates to transmit another part of allocated PUSCH PRBs; ‘11’ indicates to transmit the PUSCH.

18. The apparatus according to claim 12 , wherein a new SRS trigger type has a higher priority than existing SRS trigger types.

19. The apparatus according to claim 11 , wherein the at least one memory and the computer program code are further configured, with the at least one processor, to cause the apparatus at least to: define a zero-power SRS configuration to allow for flexible muting of the last symbol.

20. The apparatus according to claim 12 , wherein, when use of a new SRS trigger type is configured, hybrid automatic repeat request (HARQ) re-transmissions follow a pre-defined codepoint of the new SRS trigger type or follow puncturing rules defined for an overlapping cell-specific SRS.

21. The apparatus according to claim 11 , wherein the apparatus comprises an evolved node B (eNB).

22. A computer program, embodied on a non-transitory computer readable medium, the computer program when executed by a processor, causes the processor to: incorporate into an uplink grant message for a physical uplink shared channel (PUSCH) information on whether a last symbol of an uplink subframe that is reserved by a base station in every n th subframe for sounding reference signal (SRS) transmissions, is available for the PUSCH; and transmit the uplink grant message comprising the information on the last symbol to a user equipment, wherein the user equipment is configured to ignore cell-specific SRS subframe configuration when determining whether the last symbol of the uplink subframe is available for transmission of the PUSCH.

23. A method, comprising: receiving, by a user equipment, an uplink grant message for a physical uplink shared channel (PUSCH) comprising information indicating whether a last symbol of an uplink subframe that is reserved by a base station in every n th subframe for sounding reference signal (SRS) transmissions, is available for the PUSCH; and determining from the received information whether the last symbol is available for the PUSCH; wherein the user equipment is configured to ignore cell specific SRS subframe configuration when determining whether the last symbol of the uplink subframe is available for transmission of the PUSCH.

24. The method according to claim 23 , wherein one bit in the uplink grant message indicates whether the last symbol is available for the PUSCH, and another bit in the uplink grant message indicates whether the user equipment should send an SRS.

25. A method, comprising: receiving, by a user equipment, an uplink grant message comprising information indicating whether a last symbol of an uplink subframe for sounding reference signal (SRS) transmissions, is available for a physical uplink shared channel (PUSCH); and determining from the received information whether the last symbol is available for the PUSCH, wherein the user equipment is configured to ignore cell specific SRS subframe configuration when determining whether the last symbol of the uplink subframe is available for transmission of the PUSCH, wherein one bit in the uplink grant message indicates whether the last symbol is available for the PUSCH, and another bit in the uplink grant message indicates whether the user equipment should send an SRS, wherein said one bit indicating whether the last symbol is available for the PUSCH and said one bit indicating indicate whether the user equipment should send an SRS are interpreted jointly according to: ‘00’ indicates to the user equipment to not transmit an SRS, and to puncture the PUSCH; ‘01’ indicates to the user equipment to not transmit an SRS, and to transmit the PUSCH in the last symbol; ‘10’ indicates to the user equipment to transmit an SRS, and to puncture the PUSCH; ‘11’ indicates to the user equipment to transmit an SRS, and to transmit t PUSCH.

26. A method, comprising: receiving, by a user equipment, an uplink grant message comprising information indicating whether a last symbol of an uplink subframe for sounding reference signal (SRS) transmissions, is available for a physical uplink shared channel (PUSCH); and determining from the received information whether the last symbol is available for the PUSCH, wherein the user equipment is configured to ignore cell specific SRS subframe configuration when determining whether the last symbol of the uplink subframe is available for transmission of the PUSCH, wherein one bit in the uplink grant message indicates whether the last symbol is available for the PUSCH, and another bit in the uplink grant message indicates whether the user equipment should send an SRS, wherein a first and a second SRS configuration are provided, and wherein said one bit indicating whether the last symbol is available for the PUSCH and said one bit indicating indicate whether the UE should send an SRS are interpreted jointly according to: ‘00’ indicates to not transmit an SRS, and puncture the PUSCH; ‘01’ indicates to not transmit an SRS, and transmit the PUSCH in the last symbol; ‘10’ indicates to transmit a first SRS configuration, and puncture the PUSCH; ‘11’ indicates to transmit a second SRS configuration, and puncture the PUSCH.

27. The method according to claim 23 , wherein the receiving further comprises: receiving the information comprising two bits in the uplink grant message to indicate whether the last symbol is available for the PUSCH.

28. The method according to claim 23 , wherein, when use of a new SRS trigger type is configured, hybrid automatic repeat request (HARQ) re-transmissions follow a pre-defined codepoint of the new SRS trigger type or follow puncturing rules defined for an overlapping cell-specific SRS.

29. The method according to claim 23 , wherein the information comprises a new SRS trigger type, and wherein the new SRS trigger type has a higher priority than existing SRS trigger types.

30. An apparatus, comprising: at least one processor; and at least one memory comprising computer program code, the at least one memory and the computer program code, with the at least one processor, causing the apparatus at least to receive an uplink grant message for a physical uplink shared channel (PUSCH) comprising information indicating whether a last symbol of an uplink subframe that is reserved by a base station in every n th subframe for sounding reference signal (SRS) transmissions, is available for the PUSCH; and determine from the received information whether the last symbol is available for the PUSCH, wherein the apparatus is configured to ignore cell specific SRS subframe configuration when determining whether the last symbol of the uplink subframe is available for transmission of the PUSCH.

31. The apparatus according to claim 30 , wherein one bit in the uplink grant message indicates whether the last symbol is available for the PUSCH, and another bit in the uplink grant message indicates whether the apparatus should send an SRS.

32. The apparatus according to claim 31 , wherein said one bit indicating whether the last symbol is available for the PUSCH and said one bit indicating indicate whether the apparatus should send an SRS are interpreted jointly according to: ‘00’ indicates to the apparatus to not transmit an SRS, and to puncture the PUSCH; ‘01’ indicates to the apparatus to not transmit an SRS, and to transmit the PUSCH in the last symbol; ‘10’ indicates to the apparatus to transmit an SRS, and to puncture the PUSCH; ‘11’ indicates to the apparatus to transmit an SRS, and to transmit the PUSCH.

33. The apparatus according to claim 31 , wherein a first and a second SRS configuration are provided, and wherein said one bit indicating whether the last symbol is available for the PUSCH and said one bit indicating indicate whether the UE should send sounding reference signal (SRS) are interpreted jointly according to: ‘00’ indicates to not transmit an SRS, and puncture the PUSCH; ‘01’ indicates to not transmit an SRS, and transmit the PUSCH in the last symbol; ‘10’ indicates to transmit a first SRS configuration, and puncture the PUSCH; ‘11’ indicates to transmit a second SRS configuration, and puncture the PUSCH.

34. The apparatus according to claim 30 , wherein the at least one memory and the computer program code are further configured, with the at least one processor, to cause the apparatus at least to: receive the information comprising two bits in the uplink grant message to indicate whether the last symbol is available for the PUSCH.

35. The apparatus according to claim 30 , wherein, when use of a new SRS trigger type is configured, hybrid automatic repeat request (HARQ) re-transmissions follow a pre-defined codepoint of the new SRS trigger type or follow puncturing rules defined for an overlapping cell-specific SRS.

36. The apparatus according to claim 30 , wherein the information comprises a new SRS trigger type, and wherein the new SRS trigger type has a higher priority than existing SRS trigger types.

37. The apparatus according to claim 30 , wherein the apparatus comprises a user equipment.

38. A computer program, embodied on a non-transitory computer readable medium, the computer program, when executed by a processor, causes the processor to: receive an uplink grant message for a physical uplink shared channel (PUSCH) comprising information indicating whether a last symbol of an uplink subframe that is reserved by a base station in every n th subframe for sounding reference signal (SRS) transmissions, is available for the PUSCH; and determine from the received information whether the last symbol is available for the PUSCH, wherein the determining comprises ignoring cell specific SRS subframe configuration when determining whether the last symbol of the uplink subframe is available for transmission of the PUSCH.