Resource Allocation for Secure Communications in Cooperative Cognitive Wireless Powered Communication Networks

TL;DR

This paper introduces a cooperative protocol for cognitive wireless powered communication networks that enhances secondary user throughput and primary user security through resource allocation algorithms, even with uncertain eavesdropper information.

Contribution

It proposes a novel cooperative protocol and resource allocation algorithms for secure spectrum sharing in CWPCNs, addressing both perfect and imperfect eavesdropper channel information.

Findings

Improved secondary user ergodic rate and primary user security.

Effective resource allocation algorithms for various EAV CSI scenarios.

Enhanced security performance with unknown EAV CSI.

Abstract

We consider a cognitive wireless powered communication network (CWPCN) sharing the spectrum with a primary network who faces security threats from eavesdroppers (EAVs). We propose a new cooperative protocol for the wireless powered secondary users (SU) to cooperate with the primary user (PU). In the protocol, the SUs first harvest energy from the power signals transmitted by the cognitive hybrid access point during the wireless power transfer (WPT) phase, and then use the harvested energy to interfere with the EAVs and gain transmission opportunities at the same time during the wireless information transfer (WIT) phase. Taking the maximization of the SU ergodic rate as the design objective, resource allocation algorithms based on the dual optimization method and the block coordinate descent method are proposed for the cases of perfect channel state information (CSI) and collusive/non-collusive EAVs under the PU secrecy constraint. More PU favorable greedy algorithms aimed at minimizing the PU secrecy outage probability are also proposed. We furthermore consider the unknown EAVs' CSI case and propose an efficient algorithm to improve the PU security performance. Extensive simulations show that our proposed protocol and corresponding resource allocation algorithms can not only let the SU gain transmission opportunities but also improve the PU security performance even with unknown EAVs' CSI.