Estimation of forward link signal-to-noise ratio
View Patent ↗The present invention provides a technique for estimating signal-to-noise ratio of a forward traffic channel in a wireless communication system that utilizes a pilot channel. Initially, a signal-to-noise ratio is estimated for the pilot channel and an adjustment to convert the signal-to-noise ratio for the pilot channel to a signal-to-noise ratio for the forward traffic channel is estimated. The adjustment is then applied to the signal-to-noise ratio for the pilot channel to obtain an estimate for the signal-to-noise ratio for the forward traffic channel.
1. A method for estimating signal-to-noise ratio of a forward traffic channel in a wireless communication system that utilizes a pilot channel, said method comprising:
estimating a signal-to-noise ratio for the pilot channel;
estimating an adjustment to convert the signal-to-noise ratio for the pilot channel to a signal-to-noise ratio for the forward traffic channel; and
applying the adjustment to the signal-to-noise ratio for the pilot channel to obtain an estimate for the signal-to-noise ratio for the forward traffic channel,
wherein the adjustment is formed together by a fast correction component and a slow correction component, such that the fast and slow correction components are utilized jointly, instead of separately, when the adjustment is applied.
2. A method according to claim 1 , wherein the signal-to-noise ratio for the pilot channel is added to the adjustment to obtain the signal-to-noise ratio for the forward traffic channel.
3. A method according to claim 1 , wherein the fast correction component is updated more frequently than the slow correction component.
4. A method according to claim 3 , wherein the slow correction component is updated at intervals of at least one frame.
5. A method according to claim 3 , wherein the fast correction component is updated at an interval of not more than four power control groups.
6. A method according to claim 3 , wherein the fast correction component is based on a power control signal sent to a base station in the wireless communication system.
7. A method according to claim 3 , wherein the slow correction component is based on an estimation of a ratio of traffic channel power to a second estimation of traffic channel power that is based on pilot channel power.
8. A method according to claim 3 , wherein the slow correction component is applied only if an estimate for the slow correction component has a magnitude that exceeds a set threshold.
9. A method according to claim 3 , further comprising a step of estimating a power control step size for a base station in the communication system using a result from an estimation of the slow correction component.
10. A method according to claim 1 , wherein the signal-to-noise ratio for the pilot channel is estimated by summing signal-to-noise ratios for each finger in a Rake receiver.
11. A method according to claim 1 , further comprising a step of utilizing the estimate for the signal-to-noise ratio for the forward traffic channel to perform forward channel power control.
12. An apparatus for estimating signal-to-noise ratio of a forward traffic channel in a wireless communication system that utilizes a pilot channel, said apparatus comprising:
means for estimating a signal-to-noise ratio for the pilot channel;
means for estimating an adjustment to convert the signal-to-noise ratio for the pilot channel to a signal-to-noise ratio for the forward traffic channel; and
means for applying the adjustment to the signal-to-noise ratio for the pilot channel to obtain an estimate for the signal-to-noise ratio for the forward traffic channel,
wherein the adjustment is formed together by a fast correction component and a slow correction component, such that the fast and slow correction components are utilized jointly, instead of separately, when the adjustment is applied.
13. An apparatus according to claim 12 , wherein the signal-to-noise ratio for the pilot channel is added to the adjustment to obtain the signal-to-noise ratio for the forward traffic channel.
14. An apparatus according to claim 12 , wherein the fast correction component is updated more frequently than the slow correction component.
15. An apparatus according to claim 14 , wherein the slow correction component is updated at intervals of at least one frame.
16. An apparatus according to claim 14 , wherein the fast correction component is updated at an interval of not more than four power control groups.
17. An apparatus according to claim 14 , wherein the fast correction component is based on a power control signal sent to a base station in the wireless communication system.
18. An apparatus according to claim 14 , wherein the slow correction component is based on an estimation of a ratio of traffic channel power to a second estimation of traffic channel power that is based on pilot channel power.
19. An apparatus according to claim 14 , wherein the slow correction component is applied only if an estimate for the slow correction component has a magnitude that exceeds a set threshold.
20. An apparatus according to claim 14 , further comprising a means for estimating a power control step size for a base station in the communication system using a result from an estimation of the slow correction component.
21. An apparatus according to claim 12 , wherein the signal-to-noise ratio for the pilot channel is estimated by summing signal-to-noise ratios for each finger in a Rake receiver.
22. An apparatus according to claim 12 , further comprising means for utilizing the estimate for the signal-to-noise ratio for the forward traffic channel to perform forward channel power control.