On the delay/throughput-security tradeoff in wiretap TDMA networks with buffered nodes

Abstract

In this paper, we investigate the tradeoff between security and throughput and between security and queuing delay in wiretap time-division multiple access (TDMA) networks. We derive a simple relationship, characterized by a single key system parameter, between the stable-throughput region, where there are no perfect secrecy constraints on the data transmissions, and the secure stable-throughput region, where there are perfect secrecy constraints. We quantify the impact of the perfect secrecy constraints on the network's average queuing delay and propose a novel cross-layer security scheme for delaylimited applications. We establish an insightful link between computational security (i.e., upper-layer security implemented through cryptographic schemes) and physical-layer (informationtheoretically proved) security. For the two-user case, we derive a closed-form expression for the network's minimum average queuing delay under the proposed security scheme and provide a relationship between the network's minimum queuing delay under perfect secrecy constraints and computational-only secrecy constraints. Moreover, we investigate the impact of cooperative jamming on achieving perfect secrecy, minimum network's queuing delay, and maximum throughput. We verify our theoretical findings through simulations. 2019 IEEE.