Performance of ad hoc wireless networks with Aloha and PR-CSMA MAC protocols

In this paper, bit error rate (BER) performance and connectivity characteristics of multi-hop ad hoc wireless networks are analyzed under a circuit-switched network communication scheme characterized by the creation of a multi-hop communication route, through intermediate relay nodes, for each source-destination pair. The proposed transmission scheme is packetized yet it does not employ retransmissions: in this sense, it can be considered as a hybrid scheme between circuit switching and packet switching. The ideal limiting performance under the assumption of no inter-node interference (INI) is evaluated. In particular, the concept of minimum spatial energy density is introduced, and quantified with a precise expression in the case of uncoded binary phase shift keying (BPSK) transmission. A realistic scenario with INI is then considered, and two different medium access control (MAC) protocols are proposed: Aloha and "per-route" carrier sense multiple access (PR-CSMA). In both cases, the BER performance is analyzed. Results show that MAC and physical layers are strictly interrelated, and designing one without considering the other may lead to wrong choices in ad hoc wireless network design.