On the capacity of cellular CDMA with successive decoding and controlled power disparities

Abstract

In a cellular CDMA system, the received powers from mobiles that are close to the base station form a dominant factor in the interference presented to mobiles that are farther away. Conventional power control techniques try to eliminate this problem by maintaining equal received powers for all users. However, recent research has produced successive interference cancellation schemes that rely on controlled disparities between the powers of users. In this work, we study capacity gains in cellular CDMA from ideal successive decoding. Our studies show that successive decoding with power control enforcing appropriately disparate powers can approximately double the capacity when compared with a conventional system using single user decoding. The idea of disparities among users also appears naturally when different users transmit at different rates. We study the capacity regions for the multi-rate case and find that successive decoding provides even larger capacity gains over single user decoding in this case.