Downlink performance analysis of DS-CDMA system with base station diversity
Hemabh Shekhar · 2002
In this thesis we study the performance of DS-CDMA downlink with base station diversity (BSD), since most of the works till date have concentrated on uplink. A BSD architecture is considered with three base stations (BSs) per cell and its performance compared against the conventional cellular network with one BS per cell. A mobile station (MS) will be connected to multiple BSs in its cell. In downlink each BS will transmit same data to the MS using certain power control scheme. Three power control schemes have been studied. One scheme distributes the power equally among all the BSs communicating to a certain MS, maintaining a constant transmit power. Second scheme maintains a constant power at the MS receiver taking into account the path loss. Third scheme analyzed is the famous water filling solution to compute the transmitted power in each BS-MS channel keeping the total power level constant. This scheme will have the advantage that transmitted power from each base station will be changed adaptively based on the channel SNR and interference conditions to provide maximum channel capacity. However it has been concluded from this work that this scheme is suitable for a MIMO system unlike this work which considers a MISO system. A conventional matched filter receiver is implemented at the MS. The communication channel has been modeled to have AWGN, frequency non-selective fast rayleigh multipath fading, considering the effect of path loss and MAI.