Truncated power control in code-division multiple-access communications

We analyze the performance of truncated power control in a code-division mu ltiple-access (CDMA) communication system. This power control scheme compen sates for propagation gain above a certain cutoff fade depth: below the cut off level, data transmission is suspended, We assume a channel with fast Ra yleigh fading and slow lognormal shadowing plus path loss, where truncated power control is applied to the shadowing plus path loss and a RAKE receive r combines the Rayleigh fading multipath components separated by more than a chip time. We find that truncated power control exhibits both a power and capacity gain. These performance improvements result from the fact that wi th truncated power control, less power is wasted compensating for deep fadi ng, and mobiles on the cell boundaries cause less interference to adjacent cells. We find that truncated power control is most effective for channels with large power fluctuations or with large background noise.