Method and apparatus for selecting a resource assignment
A method and apparatus reduce latency of Long Term Evolution (LTE) uplink transmissions. Configuration information regarding a Downlink Control Information (DCI) message for a Physical Uplink Shared Channel (PUSCH) transmission can be acquired. The DCI message can be received on a Physical Downlink Control Channel (PDCCH) in a first subframe. The DCI message can indicate a plurality of resource assignments in a second subframe for an uplink carrier from which a User Equipment (UE) can select one resource assignment for transmission on the uplink carrier. The DCI message can be Cyclic Redundancy Check (CRC) scrambled by a Radio Network Temporary Identifier (RNTI) that is indicated via higher layers that are higher than a physical layer. A resource assignment can be selected from the plurality of resource assignments using a selection criterion. A data packet can be transmitted on the PUSCH in a resource of the selected resource assignment in the second subframe on the uplink carrier.
1. A method in a user equipment, the method comprising:
acquiring configuration information regarding a downlink control information message for a physical uplink shared channel transmission;
receiving the downlink control information message on a physical downlink control channel in a first subframe, the downlink control information message indicating a plurality of resource assignments in a second subframe for an uplink carrier from which the user equipment selects one resource assignment for transmission on the uplink carrier, where the downlink control information message is cyclic redundancy check scrambled by a radio network temporary identifier that is indicated via higher layers that are higher than a physical layer;
selecting a resource assignment from the plurality of resource assignments using a selection criterion; and
transmitting a data packet on the physical uplink shared channel in a resource of the selected resource assignment in the second subframe on the uplink carrier.
2. The method according to claim 1 , wherein each resource assignment of the plurality of resource assignments has a same number of resource blocks.
3. The method according to claim 1 ,
wherein the user equipment has a cell radio network temporary identifier, and
wherein the method further comprises determining a cyclic shift for a demodulation reference signal for the transmission of the data packet based on the cell radio network temporary identifier.
4. The method according to claim 1 , wherein the method further comprises determining a cyclic shift for a demodulation reference signal for the transmission based on at least one field indicated in the downlink control information message.
5. The method according to claim 1 ,
wherein the user equipment has a cell radio network temporary identifier, and
wherein the method further comprises determining an orthogonal cover code sequence for a demodulation reference signal for the transmission of the data packet based on the cell radio network temporary identifier.
6. The method according to claim 1 , wherein the method further comprises determining an orthogonal cover code sequence for a demodulation reference signal for the transmission based on at least one field indicated in the downlink control information message.
7. The method according to claim 1 , wherein the number of resource assignments is explicitly indicated in the downlink control information message.
8. The method according to claim 1 , wherein the number of resource assignments is implicitly indicated in the downlink control information message.
9. The method according to claim 1 , wherein the selection criterion is a random selection of the resource assignment from the plurality of resource assignments.
10. The method according to claim 1 , wherein the selection criterion is based on at least one parameter measured by the user equipment.
11. The method according to claim 1 ,
wherein the user equipment has a user equipment identifier, and
wherein the selection criterion is based on at least a hashing function based on the user equipment identifier.
12. The method according to claim 1 , wherein the user equipment has a cell radio network temporary identifier and a contention-based cell radio network temporary identifier configured via higher layers and the downlink control information is scrambled by the contention-based cell radio network temporary identifier.
13. The method according to claim 1 , further comprising:
determining a cyclic shift for a demodulation reference signal for the transmission; and
selecting a scrambling initialization for physical uplink shared channel transmission based on at least the determined cyclic shift for the demodulation reference signal for the transmission.
14. The method according to claim 1 , further comprising:
determining an orthogonal cover code sequence for a demodulation reference signal for the transmission; and
selecting a scrambling initialization for physical uplink shared channel transmission based on at least the determined orthogonal cover code sequence for the demodulation reference signal for the transmission.
15. An apparatus comprising:
a controller configured to acquire configuration information regarding a downlink control information message for a physical uplink shared channel transmission;
a transceiver configured to receive the downlink control information message on a physical downlink control channel in a first subframe, where the downlink control information message indicates a plurality of resource assignments in a second subframe for an uplink carrier from which the apparatus selects one resource assignment for transmission on the uplink carrier, and where the downlink control information message is cyclic redundancy check scrambled by a radio network temporary identifier that is indicated via higher layers that are higher than a physical layer; and
wherein the controller is configured to select a resource assignment from the plurality of resource assignments using a selection criterion, and
wherein the transceiver is configured to transmit a data packet on the physical uplink shared channel in a resource of the selected resource assignment in the second subframe on the uplink carrier.
16. The apparatus according to claim 15 , wherein each resource assignment of the plurality of resource assignments has a same number of resource blocks.
17. The apparatus according to claim 15 ,
wherein the apparatus has a cell radio network temporary identifier, and
wherein the controller determines a parameter for a demodulation reference signal for the transmission of the data packet based on the cell radio network temporary identifier.
18. The apparatus according to claim 15 , wherein the controller determines a parameter for a demodulation reference signal for the transmission based on at least one field indicated in the downlink control information message.
19. The apparatus according to claim 15 ,
wherein the apparatus has an apparatus identifier, and
wherein the selection criterion is based on at least a hashing function based on the apparatus identifier.
20. The apparatus according to claim 15 , wherein the apparatus has a cell radio network temporary identifier and a contention-based cell radio network temporary identifier configured via higher layers and the downlink control information is scrambled by the contention-based cell radio network temporary identifier.