Method and system for closed loop power control in wireless systems
OwnerLijun Qian, Zoran Gajicinventors
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Abstract
A system for closed loop power control in a mobile communication system comprises error determination process for determining an error between a target SIR and a received SIR (12, 14) and a power control scheme for determining a power change associated with error (18). As a result, the system controls the gain of power transmission (19) in order to achieve minimum error at a subsequent time instant.
Claims20
A transmission power control method for a mobile communication system comprising the steps of:
- determining a target Signal-to-Interference Ratio (SIR);
- estimating a received SIR of a base station;
- determining error between the received SIR and the target SIR;
- and
- determining a power control scheme at a power controller of the base station to determine a power change for the transmission power of a mobile to the base station in proportion to the error;
- and
- selecting a gain of the power controller to achieve minimum error at a subsequent time instant.
The method of claim 10 wherein overhead of said power change is in the range of 3 to 5 bits per frame.
A transmission power control system for a mobile communication system comprising:
- means for determining a target Signal-to-Interference Ratio (SIR);
- means for estimating a received SIR of a base station;
- means for determining error between the received SIR and the target SIR;
- and
- means for determining a power control scheme at a power controller of the base station to determine a power change for the transmission power of a mobile to the base station in proportion to the error;
- and
- means for selecting a gain of the power controller to achieve minimum error at a subsequent time instant.
The system of claim 15 wherein said power control scheme is
- 26 p i ( k + 1 ) = { p min if δ ^ i ( k + 1 ) > γ i tar p min p max if δ ^ i ( k + 1 ) < γ i tar p max p i ( k ) + α ^ i ( k ) e i ( k ) = γ i tar δ i ( k + 1 ) o . w .
- where the gain applied to the power control scheme {circumflex over (α)}i(k) is defined by
- 27 α ^ i ( k ) = { 1 δ ^ i ( k ) ( 1 - γ i tar e i ( k ) ) + 1 δ ^ i ( k + 1 ) γ i tar e i ( k ) if e i ( k ) ≠ 0 0 if e i ( k ) = 0
- where {circumflex over (δ)} is estimated channel variation.
Dependencies are inferred from the claim text.