Power-controlled CDMA cell sectorization with multiuser detection: A comprehensive analysis on uplink and downlink

We consider the joint optimization problem of cell sectorization, transmit power control and multiuserdetection for a CDMA cell. Given the number of sectors and user locations, the cell is appropriatelysectorized such that the total transmit power, as well as the receiver filters, is optimized. We formulatethe corresponding joint optimization problems for both the uplink and the downlink and observe thatin general, the resulting optimum transmit and receive beamwidth values for the directional antennasat the base station are different. We present the optimum solution under a general setting with arbitrarysignature sets, multipath channels, realistic directional antenna responses and identify its complexity.We propose a low-complexity sectorization algorithm that performs near optimum and compare itsperformance with that of optimum solution. The results suggest that by intelligently combining adaptivecell sectorization, power control, and linear multiuser detection, we are able to increase the user capacityof the cell. Numerical results also indicate robustness of optimum sectorization against Gaussian channelestimation error.