Band based power control (BBPC) for MC-CDMA radio interface

This paper highlights limitations of the ECPC (each carrier power control) concept (S.P.V. Jarot and M. Nakagawa, Proc. IEEE Int. Symp. on Computers and Comms., pp. 331-337, 1999) - originally proposed for OFDM-DS-CDMA - when extended to MC-CDMA (multi-carrier code division multiple access) systems. First, its impractical signaling overhead of 80%; secondly its inability to be used as an uplink power control mechanism. Then we propose BBPC (hand based power control) as a practical alternative to ECPC for MC-CDMA systems. Unlike ECPC that controls power on each carrier basis, BBPC assigns the same power level to a band of carriers (lying within coherence bandwidth of channel). It has been shown that with a nominal performance loss, BBPC reduces the signaling overheads to 2.5% and by employing the control index estimator after de-spreading, it can be used as an uplink power control mechanism for MC-CDMA. We have used SIR (signal to interference ratio) as a power control index, BER and standard deviation of power control error as performance metrics.