Aeronautical relay network performance for several duplexing, multiplexing, and multiple access schemes

Research interest in ad hoc networks has rapidly grown in the last few years. Such networks have application in both military and commercial systems such as satellites, sensors, aeronautical systems, etc. Ad hoc networks can offer numerous benefits including range extension, capacity enhancement, and reduced infrastructure costs. The choice of duplexing, multiplexing, and multiple access (D/M/MA) techniques used in these ad hoc networks has substantial impact on network performance, yet the comparison of different D/M/MA schemes has seen surprisingly little attention. In this paper, we first address and compare several orthogonal D/M/MA schemes in an “extreme” ad hoc network topology-pure relay networks, which have been used and will continue to be used in aviation networks. Our focus is on the air-to-air network case, with a near-free-space propagation model, but results are easily generalizable to other propagation conditions. Although commonly employed “time-division-only” techniques appear adequate in some cases, we conclude that for a peak power/cost constraint, hybrid time-frequency (TF) schemes with continuous single-carrier waveforms are superior to schemes with “bursted” and/or multi-carrier waveforms in terms of range, achievable data rate, and capacity, especially for long range aeronautical networks. Nonorthogonal techniques with frequency/time reuse that consider inter-node interference are also investigated. A signal-to-interference-ratio (SIR) expression is derived for a given resource reuse factor and number of nodes to provide relay reuse design guidelines. We also investigate bit error ratio (BER) performance for relay networks both theoretically and via Monte Carlo simulation. Our results show very good agreement between simulations and theory. Results also illustrate the so-called “multi-hop gains” over single-hop transmission for a given end-to-end route distance and transmit power- We also conclude that appropriately designed TF schemes are preferable in terms of BER in relay networks.