QoS-Based Design for Security Enhancement in TDMA-Based Wireless Networks

This paper investigates a cross-layer design to secure a set of buffered legitimate source nodes wishing to communicate with a common destination node. We assume a slotted-system and time-division multiple-access spectrum sharing where only one legitimate source node is allowed to transmit in a given time slot. The users' assignment probabilities to the time slots are optimized to satisfy a certain quality-of-service (QoS) requirement for all the legitimate source nodes. These probabilities are shown to be functions of the system parameters, secrecy rate outage probabilities, and arrival rates to the users' queues. To further improve the system's security and maximize the network performance measured by QoS metrics, i.e., secure stable-throughput region, we propose and compare beamforming-based cooperative jamming schemes that depend on the availability of the eavesdropper's instantaneous channel state information at the legitimate nodes. Each of the jamming schemes results in a different set of secrecy outage probabilities for the legitimate users which vary the time-assignment probabilities. We derive the secrecy stable- throughput region of the investigated wireless network. Our proposed jamming schemes achieve significant increase in the secure throughput over the fixed-jamming and no-jamming schemes.