Apparatus and method for power adjustment for link imbalances
Methods and devices for dynamically controlling a transmission power of an HS-DPCCH are disclosed. A wireless user equipment receives downlink transmissions on a data channel from a serving cell, and determines a rate of duplicate packets on the data channel. The UE interprets a high rate of duplicate transmissions as an indication that the HS-DPCCH is not being successfully decoded, and therefore increases the transmission power of the HS-DPCCH. Correspondingly, the UE interprets a low rate of duplicate transmissions as an indication that the HS-DPCCH may have too high a transmission power, and therefore decreases the transmission power of the HS-DPCCH.
1. A method of wireless communication operable at a user equipment, comprising:
determining a rate of duplicate packets received on a downlink data channel, wherein the rate indicates a number of retransmissions of packets that are previously transmitted on the downlink data channel over a time period and acknowledged by the user equipment;
determining a transmission power for transmitting an uplink response channel in accordance with the rate of duplicate packets received on the downlink data channel; and
transmitting the uplink response channel utilizing the determined transmission power.
2. The method of claim 1 , wherein the uplink response channel is configured to carry feedback information relating to the downlink data channel.
3. The method of claim 2 , wherein the feedback information comprises at least one of a hybrid automatic repeat request (HARQ) acknowledgment message or downlink channel quality information.
4. The method of claim 1 , wherein the determining of the rate of duplicate packets comprises:
receiving a first packet on the downlink data channel;
transmitting a hybrid automatic repeat request (HARQ) acknowledgment message corresponding to the first packet;
receiving a second packet on the downlink data channel; and
storing an indicator of a duplicate packet corresponding to a determination that the second packet is a retransmission of the first packet.
5. The method of claim 1 , wherein the determining of the transmission power comprises:
increasing a transmission power offset in accordance with the determined rate of duplicate packets being greater than a first threshold; and
decreasing the transmission power offset in accordance with the determined rate of duplicate packets being less than a second threshold.
6. The method of claim 5 ,
wherein the increasing of the transmission power offset further comprises determining that the determined rate of duplicate packets is greater than the first threshold for a time that is greater than a first predetermined time, and
wherein the decreasing of the transmission power offset further comprises determining that the determined rate of duplicate packets is less than the second threshold for a time that is greater than a second predetermined time.
7. The method of claim 5 , wherein the transmission power offset comprises a gain ratio for the response channel relative to an uplink control channel configured to carry control information relating to a dedicated data channel.
8. The method of claim 7 , wherein the determining of the transmission power further comprises:
receiving a first control message comprising a first transmission power offset,
wherein first transmission power offset comprises a lower bound for the transmission power offset.
9. The method of claim 8 , further comprising:
receiving a second control message comprising a second transmission power offset,
wherein the second transmission power offset comprises an upper bound for the transmission power offset.
10. The method of claim 9 , wherein the first control message and the second control message each comprises radio resource control (RRC) signaling.
11. A user equipment configured for wireless communication, comprising:
at least one processor;
a memory coupled to the at least one processor;
a transmitter coupled to the at least one processor for transmitting an uplink response channel and an uplink control channel; and
a receiver coupled to the at least one processor for receiving a downlink data channel,
wherein the at least one processor is configured to:
determine a rate of duplicate packets received on the downlink data channel, wherein the rate indicates a number of retransmissions of packets that were previously transmitted on the downlink data channel over a time period and acknowledged by the user equipment;
determine a transmission power for transmitting the uplink response channel in accordance with the rate of duplicate packets received on the downlink data channel; and
transmit the uplink response channel utilizing the determined transmission power.
12. The user equipment of claim 11 , wherein the uplink response channel is configured to carry feedback information relating to the downlink data channel.
13. The user equipment of claim 12 , wherein the feedback information comprises at least one of a hybrid automatic repeat request (HARQ) acknowledgment message or downlink channel quality information.
14. The user equipment of claim 11 , wherein the at least one processor, being configured to determine the rate of duplicate packets, is further configured to:
receive a first packet on the downlink data channel;
transmit a hybrid automatic repeat request (HARQ) acknowledgment message corresponding to the first packet;
receive a second packet on the downlink data channel; and
store, in the memory, an indicator of a duplicate packet corresponding to a determination that the second packet is a retransmission of the first packet.
15. The user equipment of claim 11 , wherein the at least one processor, being configured to determine the transmission power, is further configured to:
increase a transmission power offset in accordance with the determined rate of duplicate packets being greater than a first threshold; and
decrease the transmission power offset in accordance with the determined rate of duplicate packets being less than a second threshold.
16. The user equipment of claim 15 ,
wherein the increasing of the transmission power offset further comprises determining that the determined rate of duplicate packets is greater than the first threshold for a time that is greater than a first predetermined time, and
wherein the decreasing of the transmission power offset further comprises determining that the determined rate of duplicate packets is less than the second threshold for a time that is greater than a second predetermined time.
17. The user equipment of claim 15 , wherein the transmission power offset comprises a gain ratio for the response channel relative to the uplink control channel, wherein the uplink control channel is configured to carry control information relating to a dedicated data channel.
18. The user equipment of claim 17 , wherein the at least one processor, being configured to determine the transmission power, is further configured to:
receive a first control message comprising a first transmission power offset,
wherein first transmission power offset comprises a lower bound for the transmission power offset.
19. The user equipment of claim 18 , further comprising:
receiving a second control message comprising a second transmission power offset,
wherein the second transmission power offset comprises an upper bound for the transmission power offset.
20. The user equipment of claim 19 , wherein the first control message and the second control message each comprises radio resource control (RRC) signaling.