QoS scheduling based on acceptable BER in DS/CDMA wireless networks

The design of medium access control (MAC) protocol and the ability of physical layer sufficiently affect the system performance of wireless networks. In this paper, we propose a MAC protocol based on direct sequence code division multiple access (DS-CDMA) for wireless networks to guarantee quality-of-service (QoS) which depend on acceptable bit error rate (BER) for different traffic types, named the distributed time slot reservation protocol (DTSRP). A channel is divided into control and data channels to transmit control and data packets in the corresponding control and data frames, respectively. The data frame is further subdivided into several time slots; each time slot can transmit different traffic types such as constant bit rate (CBR), variable bit rate (VBR), and available bit rate (ABR). Each station maintains the available spreading code (ASC) table to understand which time slots and spreading codes have been reserved. DTSRP will allocate time slots and the spreading code for the data frame by using the fixed time slot allocation (FTSA) or the mixed time slot allocation (MTSA). The QoS can be guaranteed by providing the reservation of time slots and the spreading code. A Markov model is applied to analyze the DTSRP DS-CDMA system; the analytical and simulation results show that the proposed DTSRP performs very well.