Power control in a wireless communication system
A method of power control in a wireless communication system wherein blocks are transmitted from a transmitter to a receiver on multiple wireless transport channels. The method comprises comparing a target signal quality value with a received signal quality value and providing the results of the comparing step to the transmitter to adjust transmit power based on the comparing step. A corresponding receiver is also provided.
1. A method of power control in a wireless communication system wherein blocks are transmitted from a transmitter to a receiver on multiple wireless transport channels, the method comprising comparing a target signal quality value with a received signal quality value and providing the results of the comparing step in the transmitter to adjust transmit power based on the comparing step, the method comprising the steps of:
determining individual target values for each of said multiple wireless transport channels;
determining if one of said multiple wireless transport channels has been inactive for a period and, if so, providing said target signal quality value at a level which is lower than an individual target value for the inactive transport channel in the case where the individual target value of the inactive transport channel exceeds a highest individual target value for active transport channels, and providing said target signal quality value at a level which is corresponding to the individual target value for the active transport channels in the case where the highest individual target value of the active transport channel exceeds the individual target value for the inactive transport channel; and
deriving said target signal quality value from said individual target values including the individual target value of the inactive transport channel.
2. A method according to claim 1 , comprising the step of, at the end of the period of inactivity, reducing the target value of the inactive transport channel by a predetermined amount.
3. A method according to claim 1 , wherein the target signal quality value is derived from said multiple individual target values by taking the greater one of the target values.
4. A method according to claim 1 , wherein the target signal quality value is a signal to interference plus noise ratio for the channel.
5. A method according to claim 1 , comprising the step of estimating the received signal quality value.
6. A method according to claim 1 , wherein the period of inactivity is monitored by counting the number of transmission time intervals during which no block is detected.
7. A method according to claim 1 , wherein the period of inactivity is monitored by counting the number of radio frames during which no block is detected.
8. A receiver for use in a wireless communication system wherein blocks are transmitted from a transmitter to the receiver on multiple wireless transport channels, the receiver comprising:
means for comparing a target signal quality value with a received signal quality value and providing the results of the comparing step to the transmitter to adjust transmit power based on the comparing step;
means for determining individual target values for each of said multiple wireless transport channels;
means for determining if one of said multiple wireless transport channels has been inactive for a period of inactivity and if so, deriving said target signal quality value using the individual target value of the inactive transport channel for the period of inactivity; and
means for following the expiry of the period of inactivity, deriving said target signal quality value from said individual target values, wherein the target value of the inactive transport channel is removed from said individual target values which are used to derive said target signal quality value for an inner-loop power control.
9. A method according to claim 8 , comprising the step of, after a further time period of inactivity, reducing the target value of the inactive transport channel further by said predetermined amount or a different predetermined amount.
10. A method according to claim 8 , wherein when the target value of the inactive transport channel falls below the target value of the active transport channel, no further reductions are made to the target value of the inactive transport channel.
11. A method according to claim 8 , wherein the target value of the inactive transport channel is reduced to an initial target value.
12. A receiver for use in a wireless communication system wherein blocks are transmitted from a transmitter to the receiver on multiple wireless transport channels, the receiver comprising:
an inner-loop power control mechanism operable to compare a target signal quality value with a received signal quality value and provide results of the comparing step to the transmitter to adjust transmit power;
means of storing individual target values for each of said multiple wireless transport channels;
means for monitoring receipt of blocks to determine if one of said multiple wireless transport channels has been inactive for a period and, if so, providing said target signal quality value at a level which is lower than an individual target value for the inactive transport channel in the case where the individual target value of the inactive transport channel exceeds a highest individual target value for active transport channels, and providing said target signal quality value at a level which is corresponding to the individual target value for the active transport channels in the case where the highest individual target value of the active transport channel exceeds the individual target value for the inactive transport channel; and
an outer-loop power control mechanism operable to derive said target signal quality value from said individual target values including the individual target value of the inactive transport channel.
13. A receiver according to claim 12 , wherein said monitoring means comprises a timer function.
14. A receiver according to claim 12 , wherein the target signal quality value is a signal to interference plus noise ratio for the channel.
15. A receiver according to claim 12 , comprising means for estimating the received signal quality value.
16. A receiver according to claim 12 , wherein the monitoring means comprises means for counting the number of transmission time intervals during which no block is detected.
17. A wireless communication system comprising a transmitter arranged to transmit wireless data on multiple transport channels and a receiver according to claim 12 .
18. A wireless communication system according to claim 17 , wherein the results of the comparing step are provided to the transmitter via a wireless transmission channel.
19. A method of power control in a wireless communication system wherein blocks are transmitted from a transmitter to a receiver on multiple wireless transport channels, the method comprising:
comparing a target signal quality value with a received signal quality value and providing the results of the comparing step to the transmitter to adjust transmit power based on the comparing step;
determining individual target values for each of said multiple wireless transport channels;
determining if one of said multiple wireless transport channels has been inactive for a period of inactivity and if so, deriving said target signal quality value using the individual target value of the inactive transport channel for the period of inactivity; and
following the expiry of the period of inactivity, deriving said target signal quality value from said individual target values, wherein the target value of the inactive transport channel is removed from said individual target values which are used to derive said target signal quality value for an inner-loop power control.