OVSF code management schemes on ad hoc networks

In the paper, we present the orthogonal variable spreading factor (OVSF) code management schemes on ad hoc networks. Ad hoc networks are wireless networks without fixed infrastructure. Each mobile node in the network may move arbitrarily, and therefore network topology changes frequently and unpredictably. Since the OVSF codes are originally used as the channelization codes in the DS-CDMA system of IMT-2000, previous schemes are centralized and cannot be applied directly to fully distributed systems such as ad hoc networks. Totally, six distributed code management schemes are proposed in the paper, and three of them heavily exploit two techniques: code reassignment and code tree management. Simulation results show that our schemes, with the help of the techniques, reduce the call-blocking rate dramatically.