Wireless Powered Cooperative Jamming for Secure OFDM System

Abstract

This paper studies the secrecy communication in an orthogonal frequency division multiplexing (OFDM) system, where a source sends confidential information to a destination in the presence of a potential eavesdropper. We employ wireless powered cooperative jamming to improve the secrecy rate of this system with the assistance of a cooperative jammer, which works in the harvest-then-jam protocol over two time-slots. In the first slot, the source sends dedicated energy signals to power the jammer; in the second slot, the jammer uses the harvested energy to jam the eavesdropper, in order to protect the simultaneous secrecy communication from the source to the destination. In particular, we consider two types of receivers at the destination, namely Type-I and Type-II receivers, which do not have and have the capability of canceling the (a-priori known) jamming signals, respectively. For both types of receivers, we maximize the secrecy rate at the destination by jointly optimizing the transmit power allocation at the source and the jammer over sub-carriers, as well as the time allocation between the two time-slots. First, we present the globally optimal solution to this problem via the Lagrange dual method, which, however, is of high implementation complexity. Next, to balance tradeoff between the algorithm complexity and performance, we propose alternative low-complexity solutions based on minorization maximization and heuristic successive optimization, respectively. Simulation results show that the proposed approaches significantly improve the secrecy rate, as compared to benchmark schemes without joint power and time allocation.Comment: This paper is submitted for possible journal publicatio

Spectral and Energy-Efficient Wireless Powered IoT Networks: NOMA or TDMA?

“…Therefore, how to efficiently utilize the scarce harvested energy becomes particularly crucial for realizing sustainable and scalable IoT networks. To this end, a "harvest and then transmit" protocol is proposed in [3]- [5] for wireless powered communication networks (WPCNs), where devices first harvest energy in the downlink (DL) for wireless energy transfer (WET) and then transmit information signals in the uplink (UL) for wireless information transmission (WIT).…”

Generalized Wireless-Powered Communications: When to Activate Wireless Power Transfer?

“…Here, E(·) and Tr(·) denote statistical expectation and the trace of a matrix, respectively. By ignoring the negligible receiver noise power for energy harvesting, the amount of energy harvested at device k under a linear energy harvesting model 1 [7], [8], [10], [13], [20] can be expressed as…”

“…Recently, wireless-powered communication networks (WPCNs) have been proposed in [7] where a dedicated power station (PS) first broadcasts energy signals to devices for downlink (DL) WPT and then the devices exploit the harvested energy for uplink wireless information transmission (UL WIT). WPCNs have been extended to different practical scenarios such as multi-antenna [8], [9], multi-carrier [10], [11], secure relay [12], and cognitive networks [13], [14]. In particular, a distributed power control algorithm is proposed in [11] to maximize the user energy efficiency.…”

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

“…The physical-layer security in WPCNs has been investigated in [20]- [26]. In [20], the source node was assumed to harvest energy from the base station and use these energy for interfering with the EAVs, and the secrecy throughput was maximized under the secrecy constraint and the transmit power constraint.…”