Power Minimization through Packet Retention in Cognitive Radio Sensor Networks under Interference and Delay Constraints: An Optimal Stopping Approach

Abstract

We consider the problem of power minimization in Cognitive Radio Sensor Networks (CRSN). The aim of this paper is twofold: First, we study the problem of packets retention in a queue with the aim of minimizing transmission power in delay-tolerant applications. The problem is classified as an optimal stopping problem. The optimal stopping rule has been derived as well. Optimal number of released packets is determined in each round through an Integer Linear Programming (ILP) optimization problem. This transmission paradigm is tested via simulations in an interference-free environment leading to a significant reduction in transmission power (at least \( 55 {\%} \)). Second, we address the problem of applying the scheme of packets retention through the Optimal Stopping Policy (OSP) to underlay CRSN where strict interference threshold does exist. Also, this problem is subjected to a delay constraint. Optimal number of released packets at this case is determined through another knapsack optimization problem that takes interference to Primary User (PU) into account. Extensive simulations that encompass dropped packet rate, Average Power per Transmitted Packet (APTP) and average consequent delay have been proposed. Simulations proved that our scheme outperforms traditional transmission method as far as dropped packet rate and APTP are substantially concerned, where end to end delay could be tolerated.