Sending and reducing uplink feedback signaling for transmission of MBMS data
The present invention is related to a method and system for sending and reducing uplink feedback signaling by a wireless transmit/receive unit (WTRU) related to transmission of multimedia broadcast multicast service (MBMS) data over a high speed downlink packet access (HSDPA) channel. A Node B may pre-allocate a time/frequency region or a common channelization code for the feedback. A triggering criterion for reporting a channel quality indicator (CQI) is set and WTRUs send a CQI to a Node B only if the triggering criterion is satisfied. The triggering criterion may be a current operating CQI value at the Node B, or based on erroneous transport block reception statistics, or a predetermined time period. A feedback reduction method related to ACK/NACK includes the WTRU sending an indication of an average number of transmissions needed to successfully decode the data instead of sending an ACK/NACK for every transmission interval.
1. A method implemented in a wireless transmit receive unit (WTRU) that communicates with a base station, the method comprising:
determining whether the WTRU is synchronized with the base station;
determining whether an uplink shared channel allocation is required;
sending a random access channel (RACH) preamble, including:
a request for an uplink shared channel allocation, wherein the request is sent in a synchronized RACH preamble or a non-synchronized RACH preamble based on the determination of whether the WTRU is synchronized with the base station: and
an indication that the cause for random access to the RACH is feedback for MBMS;
receiving the uplink shared channel allocation; and
sending a multimedia broadcast multicast service (MBMS) feedback transmission on the shared uplink channel in response to determining that an uplink shared channel allocation is required.
2. The method of claim 1 , wherein the WTRU determines that the WTRU is synchronized and accordingly uses a synchronized RACH preamble for the request.
3. The method as in claim 2 wherein the WTRU monitors its connection status and determines synchronization with the serving base station based on detecting an LTE_Active state.
4. The method of claim 1 , wherein the WTRU determines that the WTRU is non-synchronized and accordingly uses a non-synchronized RACH preamble for the request.
5. The method as in claim 4 wherein the WTRU monitors its connection status and determines non-synchronization with the serving base station based on detecting an LTE_Idle state.
6. A wireless transmit receive unit (WTRU) in a wireless communication that supports multimedia broadcast multicast service (MBMS), comprising:
a processor configured to determine whether the WTRU is synchronized with a serving base station; to determine whether an uplink shared channel allocation is required; to send a random access channel (RACH) preamble containing a request for an uplink shared channel allocation, wherein the request is sent in a synchronized RACH preamble or a non-synchronized RACH preamble based on the determination of whether the WTRU is synchronized with the serving base station, the RACH preamble further containing an indication that the cause for random access to the RACH is feedback for MBMS; to receive the uplink shared channel allocation; and to send a multimedia broadcast multicast service (MBMS) feedback transmission on the shared uplink channel in response to determining that an uplink shared channel allocation is required.
7. The WTRU as in claim 6 , wherein the processor determines that the WTRU is synchronized and accordingly uses a synchronized RACH preamble for the request.
8. The WTRU as in claim 7 wherein the processor monitors its connection status and determines synchronization with the serving base station based on detecting an LTE_Active state.
9. The WTRU of claim 6 , wherein the processor determines that the WTRU is non-synchronized and accordingly uses a non-synchronized RACH preamble for the request.
10. The WTRU as in claim 9 wherein the processor monitors its connection status and determines non-synchronization with the serving base station based on detecting an LTE_Idle state.