Access Mechanism for Multihop Cellular Networks

Abstract

We propose a CDMA-OFDM access mechanism for Multihop Cellular Networks (MCN). We construct groups within the MCN, where each group comprises of a source node, a destination node, their intermediate relay nodes and assign a correlated PN sequence to each such group. Within a particular group, a single carrier is assigned to each intermediate hop. The sub carriers assigned to the intermediate hops in a given group are mutually orthogonal. Hence the proposed OFDM is FDMA in nature. The sub carriers and transmit power levels to the relay nodes are assigned in such a way as to maximize the end-to-end throughput. The end-to-end throughput is formulated by assuming a Rayleigh flat fading channel between nodes. We present a method to reuse the PN codes assigned to the groups in a particular cell. We also introduce a novel architecture for MCN. Simulation results show that the proposed access mechanism achieves better end-to-end throughput and bit error rate (BER) performance as compared to standard access mechanisms like CDMA and OFDM-FDMA. Furthermore the proposed access mechanism has considerably higher BER performance in the presence of multiple transmit sources.