Deadline-Constrained Optimal Broadcasting under Hidden Terminals in Cognitive Networks

Abstract

This paper investigates the successful delivery probability (ps) of deadline-constrained broadcast messages in a cognitive network under the presence of hidden nodes (or terminals). The network has nodes acting as secondary users (SUs) of time slots originally assigned to some other primary users (PUs). SUs are only allowed to access unused time slots, and they do so by using the slotted-Aloha medium access control (MAC) protocol under the same access probability. ps is derived and shown to be substantially impacted due to the hidden terminals which is proposed according to a given spatial node density. Also, ps goes to zero with the increase in the number of SUs, while the limiting maximum network throughput is found to be a constant equal to 1/e as in the case of the classic slotted-Aloha, regardless of the value for the deadline for the message.