The coverage-capacity tradeoff in multiservice WCDMA cellular systems with serial interference cancellation

The uplink coverage and capacity of CDMA cellular systems with the conventional single user detector receiver are interference limited. Particularly, during the roll-out phase, the coverage of a CDMA system is uplink limited. Hence, using serial interference cancellation (SIC) at the base station is a low cost option to improve the overall performance. Considering the typical quality of service requirements of mixed services, i.e. voice and data, a new hybrid receiver structure for interference cancellation is proposed. In order to perform system level analysis, the calculation of signal-to-interference ratios is extended to the case of multiple service classes with various SIC receiver structures. Given this tooling, the optimum powers of the mobile stations are derived as a function of various system and design parameters. This enables an accurate calculation of the intracell and intercell interference. Based on this, analytical expressions are derived for the coverage-capacity tradeoff. Results show significant performance gains in terms of user capacity and cell coverage by using SIC receivers including the proposed hybrid structure that meets the delay and complexity requirements of the different service classes.