On the Stable Throughput of Cooperative Cognitive Radio Networks with Finite Relaying Buffer

TL;DR

This paper analyzes the stable throughput region of cooperative cognitive radio networks with a finite relaying buffer, formulating an optimization problem and revealing insights into cooperation benefits and buffer capacity effects.

Contribution

It characterizes the stable throughput region with a finite relaying buffer and transforms a complex problem into a linear program for analysis.

Findings

Cooperation expands the stable throughput region.

Finite relaying buffer causes a slight reduction in throughput capacity.

Mutual benefits of cooperation are confirmed.

Abstract

In this paper, we study the problem of cooperative communications in cognitive radio systems where the secondary user has limited relaying room for the overheard primary packets. More specifically, we characterize the stable throughput region of a cognitive radio network with a finite relaying buffer at the secondary user. Towards this objective, we formulate a constrained optimization problem for maximizing the secondary user throughput while guaranteeing the stability of the primary user queue. We consider a general cooperation policy where the packet admission and queue selection probabilities, at the secondary user, are both dependent on the state (length) of the finite relaying buffer. Despite the sheer complexity of the optimization problem, attributed to its non-convexity, we transform it to a linear program. Our numerical results reveal a number of valuable insights, e.g., it is always mutually beneficial to cooperate in delivering the primary packets in terms of expanding the stable throughput region. In addition, the stable throughput region of the system, compared to the case of infinite relaying queue capacity, marginally shrinks for limited relaying queue capacity.