Cooperative Access in Cognitive Radio Networks: Stable Throughput and Delay Tradeoffs

TL;DR

This paper analyzes the fundamental tradeoffs between throughput and delay in cooperative cognitive radio networks, proposing policies that improve stability and reduce delays for primary and secondary users.

Contribution

It introduces a randomized cooperative policy that balances primary and secondary user delays and derives stability and delay expressions for this approach.

Findings

Cooperation expands the stable throughput region.

The proposed policy significantly reduces delays for both users.

Quantifies the delay gains over traditional relaying methods.

Abstract

In this paper, we study and analyze fundamental throughput-delay tradeoffs in cooperative multiple access for cognitive radio systems. We focus on the class of randomized cooperative policies, whereby the secondary user (SU) serves either the queue of its own data or the queue of the primary user (PU) relayed data with certain service probabilities. The proposed policy opens room for trading the PU delay for enhanced SU delay. Towards this objective, stability conditions for the queues involved in the system are derived. Furthermore, a moment generating function approach is employed to derive closed-form expressions for the average delay encountered by the packets of both users. Results reveal that cooperation expands the stable throughput region of the system and significantly reduces the delay at both users. Moreover, we quantify the gain obtained in terms of the SU delay under the proposed policy, over conventional relaying that gives strict priority to the relay queue.