A Novel Dynamic Stepsize Power Control Algorithm for UMTS W-CDMA Systems

Power control is an essential mechanism for wideband code division multiple access (W-CDMA) systems. In our earlier work, a combined power control and a greedy rate packing (GRP) allocation scheme employing conventional fixed stepsize power control (FSPC) is discussed and evaluated. In this paper, we extend the algorithm to apply a novel dynamic stepsize power control (DSPC) algorithm to improve system performance. The dynamic stepsize (DS) is determined by the difference between the target SIR* and the received SIR. A larger stepsize is applied when the difference between the received SIR and the target SIR* is large to enhance tracking ability, and vice versa to reduce granular noise. Simulation results show the effectiveness of the proposed DSPC algorithm, with around 2% gain of throughput, 6.5% average power consumption saving and 0.5 dB standard deviation (STD) reduction of the received SIR, when compared with the FSPC scheme