Wideband coherent DS-CDMA

A coherent CDMA access architecture that supports multimedia services and also flexible system deployment is described. For the flexible use of the limited radio frequency resources, a multiple-band system is suitable. The bandwidth selected depends on the maximum data rate to be supported. This paper focuses on a 10 MHz coherent DS-CDMA system because it provides a generic model for systems using different bandwidths. Pilot symbol-aided coherent RAKE reception in the reverse link is employed to enhance the transmission quality. To allow flexible system deployment, a combination of short and long codes as spreading codes and signal-to-interference (SIR) based transmit power control are used. To flexibly offer multiple bit rate services, the traffic channel (TCH) has a maximum bit rate of 128 kbps. Within each single 128 kbps TCH, variable rate speech or low rate packet data can be transmitted based on data activated discontinuous transmission to achieve statistical multiplexing effects. Bit rate transmission higher than 128 kbps can be achieved with code multiplexing. The capacity and personal terminal transmit power of the proposed system are evaluated