Performance analysis of centralized FH-CDMA wireless networks

Centralized CDMA networks with unslotted Aloha random-access mode are consi dered. Users communicate with a central node by sharing a finite number of signature sequences assigned to the receivers at the central node. Two meth ods for sharing preamble codes are considered. In one method a common pream ble code is used by all receivers, and in the other method a distinct code is assigned for each receiver. A unified analysis framework for evaluating the performance of centralized FH-CDMA networks is developed. Closed form e xpressions for packet decoding error probabilities are derived. Numerical r esults show that common preamble codes can support only low traffic levels. However, by appropriately selecting the design parameters, acceptable leve ls of packet loss probabilities are achievable with the receiver-based prea mbles.