Controlling UE behavior for CSI/SRS reporting during DRX
The invention relates to a method for transmitting a periodic channel quality report (CSI) and/or a sounding reference symbol (SRS) from a UE to an eNodeB. To avoid double decoding at the eNodeB in transient phases, a deterministic behavior of the UE is defined by the invention, according to which the eNodeB can unambiguously determine whether the UE will transmit the CSI/SRS or not. According to one embodiment, the UL grants and/or DL assignments received until and including subframe N−4 only are considered; UL grants and/or DL assignments received by the UE after subframe N−4 are discarded for the determination. Additionally, DRX-related timers at subframe N−4 are considered for the determination. In a second embodiment, DRX MAC control elements from the eNodeB, instructing the UE to enter DRX, i.e., become Non-Active, are only considered for the determination if they are received before subframe N−4, i.e., until and including subframe N−(4+k).
1. A base station comprising:
a transmitter, which, in operation, transmits, to a mobile station, configuration information for transmitting, in subframe N from the mobile station to the base station, at least one of a channel quality information report and a sounding reference signal, and transmits, to the mobile station, a media access control (MAC) control element regarding a discontinuous reception (DRX) operation; and
a receiver, which, in operation, does not receive the channel quality information report or the sounding reference signal from the mobile station in subframe N, in case the mobile station is determined to be not in DRX Active Time in subframe N based at least on the MAC control element received by the mobile station until and including subframe N−(4+k), where k is an integer value equal to or greater than 1.
2. The base station according to claim 1 , wherein the channel quality information report and/or the sounding reference signal is periodically transmitted from the mobile station.
3. The base station according to claim 1 , wherein the transmitter, in operation, transmits, to the mobile station, an uplink resource grant for an uplink shared channel and/or downlink a resource assignment for a downlink shared channel, and the mobile station is determined to be not in DRX Active Time in subframe N based on the uplink resource grant and/or the downlink resource assignment, which is received by the mobile station until and including subframe N−(4+k).
4. The base station according to claim 1 , wherein the receiver, in operation, receives the channel quality information report and/or the sounding reference signal from the mobile station in subframe N, in case the mobile station is determined to be in DRX Active Time in subframe N.
5. The base station according to claim 1 , wherein the mobile station is determined to be in DRX Active Time in subframe N based on DRX-related timers running for the mobile station including at least one of a DRX Inactivity Timer, a DRX OnDuration Timer, and a DRX Retransmission Timer.
6. The base station according to claim 1 , wherein the transmitter, in operation, transmits, to the mobile station, radio resource control (RRC) signaling, to restrict periodic transmission of the channel quality information report to only during DRX Active Time.
7. The base station according to claim 1 , wherein any MAC control element regarding a DRX operation received by the mobile station in subframes N−(3+k) to N is disregarded.
8. The base station according to claim 1 , wherein the integer value of k is 1.
9. A method performed by a base station comprising:
transmitting, to a mobile station, configuration information for transmitting, in subframe N from the mobile station to the base station, at least one of a channel quality information report and a sounding reference signal;
transmitting, to the mobile station, a media access control (MAC) control element regarding a discontinuous reception (DRX) operation; and
receiving none of the channel quality information report or the sounding reference signal from the mobile station in subframe N, in case the mobile station is determined to be not in DRX Active Time in subframe N based at least on the MAC control element received by the mobile station until and including subframe N−(4+k), where k is an integer value equal to or greater than 1.
10. The method according to claim 9 , wherein the channel quality information report and/or the sounding reference signal is periodically transmitted from the mobile station.
11. The method according to claim 9 , comprising,
transmitting, to the mobile station, an uplink resource grant for an uplink shared channel and/or downlink a resource assignment for a downlink shared channel, wherein the mobile station is determined to be not in DRX Active Time in subframe N based on the uplink resource grant and/or the downlink resource assignment, which is received by the mobile station until and including subframe N−(4+k).
12. The method according to claim 9 , comprising,
receiving the channel quality information report and/or the sounding reference signal from the mobile station in subframe N, in case the mobile station is determined to be in DRX Active Time in subframe N.
13. The method according to claim 9 , wherein the mobile station is determined to be in DRX Active Time in subframe N based on DRX-related timers running for the mobile station including at least one of a DRX Inactivity Timer, a DRX OnDuration Timer, and a DRX Retransmission Timer.
14. The method according to claim 9 , comprising,
transmitting, to the mobile station, radio resource control (RRC) signaling, to restrict periodic transmission of the channel quality information report to only during DRX Active Time.
15. The method according to claim 9 , wherein any MAC control element regarding a DRX operation received by the mobile station in subframes N−(3+k) to N is disregarded.
16. The method according to claim 9 , wherein the integer value of k is 1.