Reliability detection of channel quality indicator (CQI) and application to outer loop power control
A method for performing outer loop power control in wireless communications is disclosed. A channel quality indicator (CQI) message is transmitted by a wireless transmit/receive unit (WTRU). The WTRU receives a power control command, the power control command being derived by: decoding the CQI message; computing a decision metric value for each symbol in the CQI message; determining whether the CQI message is erroneous; and counting a number of erroneous CQI messages, wherein the power control command is based on whether the number of erroneous CQI messages exceeds a threshold. An uplink transmission power of the WTRU is adjusted based on the power control command.
1. A method for performing outer loop power control in wireless communications, comprising:
transmitting a channel quality indicator (CQI) message by a wireless transmit/receive unit (WTRU);
receiving a power control command, the power control command being derived by:
decoding the CQI message;
computing a decision metric value for each symbol in the CQI message;
determining whether the CQI message is erroneous; and
counting a number of erroneous CQI messages, wherein the power control command is based on whether the number of erroneous CQI messages exceeds a threshold; and
adjusting an uplink transmission power of the WTRU based on the power control command.
2. The method according to claim 1 , wherein the determining includes:
selecting a largest decision metric value;
selecting a second largest decision metric value;
comparing the largest decision metric value and the second largest decision metric value against a second threshold, wherein the CQI message is erroneous on a condition that the comparison result is below the second threshold.
3. The method according to claim 2 , wherein the decision metric values are logarithmic and the comparing includes determining a difference between the largest decision metric value and the second largest decision metric value.
4. The method according to claim 2 , wherein the comparing includes calculating a ratio of the largest decision metric value to the second largest decision metric value.
5. The method according to claim 1 , wherein the counting includes using at least one counter.
6. The method according to claim 1 , wherein the counting includes counting a total number of high-speed shared control channels (HS-SICHs) received, a number of false HS-SICHs received, and a number of HS-SICHs that have been missed.
7. The method according to claim 1 , wherein:
the counting is performed over a time interval; and
the power control command is generated after expiration of the time interval.
8. A wireless transmit/receive unit (WTRU) configured to perform outer loop power control, comprising:
a transmitter configured to transmit a channel quality indicator (CQI) message;
a receiver configured to receive a power control command, the power control command being derived by:
decoding the CQI message;
computing a decision metric value for each symbol in the CQI message;
determining whether the CQI message is erroneous; and
counting a number of erroneous CQI messages, wherein the power control command is based on whether the number of erroneous CQI messages exceeds a threshold; and
a transmission power adjusting device configured to adjust an uplink transmission power of the WTRU based on the power control command.
9. The WTRU of claim 8 , wherein the determining includes:
selecting a largest decision metric value;
selecting a second largest decision metric value;
comparing the largest decision metric value and the second largest decision metric value against a second threshold, wherein the CQI message is erroneous on a condition that the comparison result is below the second threshold.
10. The WTRU according to claim 9 , wherein the decision metric values are logarithmic and the comparing includes determining a difference between the largest decision metric value and the second largest decision metric value.
11. The WTRU according to claim 9 , wherein the comparing includes calculating a ratio of the largest decision metric value to the second largest decision metric value.
12. The WTRU according to claim 8 , wherein the counting includes using at least one counter.
13. The WTRU according to claim 8 , wherein the counting includes counting a total number of high-speed shared control channels (HS-SICHs) received, a number of false HS-SICHs received, and a number of HS-SICHs that have been missed.
14. The WTRU according to claim 8 , wherein:
the counting is performed over a time interval; and
the power control command is generated after expiration of the time interval.