On the Performance of Multihop Cognitive Wireless Powered D2D Communications in WSNs

This paper studies the performance of multi-hop cognitive wireless powered device-to-device (D2D) communications in wireless sensor networks (WSNs). In our analysis, each sensor node harvests energy from multiple dedicated power beacons and shares the spectrum resources with multiple primary receivers (PRs) using underlay cognitive radio. Additionally, we consider a practical scenario of cognitive wireless powered D2D communications in WSNs, where the knowledge of interference channels is assumed to be imperfect. To improve the network performance, we propose two user scheduling schemes, namely dual-hop scheduling (DHS) and best-path scheduling (BPS) schemes. We then investigate the performance of the proposed scheduling schemes in terms of outage probability and outage floor. Through numerical results, we show that BPS scheme significantly outperforms DHS scheme, which in turns outperforms the state-of-the-art solution. Moreover, the advantages and drawbacks of each scheme are analyzed and discussed comprehensively. We also point out that the inaccurate knowledge of the interference channels significantly affects any performance metric of multi-hop cognitive D2D communications in WSNs such as outage probability, outage floor, and performance loss.

I. Introduction

Recently, wireless sensor networks (WSNs) have envisioned as a networking solution to collect and efficiently monitor the environment conditions in the coming Internet-of-Thing (IoT) era [1]. The explosion of unlicensed spectrum devices makes the traditional WSNs to undergo severe interference caused by other applications using the same spectrum [2]. Cognitive radio (CR) for WSNs is developed as a spectrum-efficient technology to reduce such interference and improve spectral utilization [3]. Therefore, various applications are evolving with IoT services and expected to be more efficient for cognitive radio WSNs in the near future.