Performance study of packet-switched TDD-CDMA multihop cellular networks

In most studies on code-division multiple access/packet reservation multiple access (CDMA/PRMA) for uplink time-division duplexing (TDD) single-hop cellular networks (SCNs), perfect power control is assumed and each time slot is divided into fixed number of code slots. It is always assumed that this capacity of a time slot can be fully utilized. However, in practice the mobile stations have limited transmit power levels, which will limit the system capacity. In this Paper, we first study the performance of CDMA/PRMA in SCNs with power control. Then we point out the key difference between the MAC schemes for TDD-CDMA SCNs and that for TDD-CDMA multihop cellular networks (MCNs), and propose a multihop medium access control (mMAC) scheme based on CDMA/PRMA for MCNs with fixed relay stations (RSs). Simulation results reveal that the performance of CDMA/PRMA in SCNs degrades as the cell radius increases. By relaying traffic through fixed RS, MCNs with the proposed mMAC scheme can substantially maintain a good performance while enlarging the cell coverage.