This paper deals with a cellular system based on Code Division Multiple Access (CDMA) and investigates the performance of Signal-to-Interference (SIR)-based Closed Loop-Power Control (CLPC) schemes taking into account errors on the feedback channel that conveys the power control command from the base station to the mobile terminals. We have evaluated both the distribution of the received power at the base station and the optimum control step size that minimizes the Control Error (CE) standard deviation, a useful measure of the CLPC performance. The impact of interference variations has been deeply investigated for different mobility scenarios and for different feedback channel error conditions.

Future wireless communication systems will provide mobile terminals with high bit-rate transmissions for accessing broadband wired networks. In this paper, we envisage a Time Division Multiple Access - Time Division Duplexing (TDMA-TDD) air interface and we propose a Medium Access Control (MAC) protocol, named Dynamic Scheduling - TDD (DS-TDD), that allows guaranteeing the QoS of different traffic classes and efficiently supports uplink/downlink traffic asymmetries. The DS-TDD performance is theoretically analyzed. Moreover, the DS-TDD protocol is compared with another scheme proposed in the literature. Finally, the impact of packet errors on the DS-TDD performance is evaluated.