Wireless-powered two-way relaying protocols for optimizing physical layer security

Kisong Lee, Jun Pyo Hong, Hyun Ho Choi, Tony Q.S. Quek

Research output: Contribution to journalArticlepeer-review

45 Scopus citations

Abstract

This paper considers a two-way relay network, in which two sources exchange data through a relay and a cooperative jammer transmits an artificial noise (AN) while a number of nearby eavesdroppers overhear to recover data from both sources. The relay harvests energy from the two source signals and the AN, and then, uses this harvested energy to forward the received signals to the two sources. Each source eliminates its own signal from the relaying signal by self-cancellation and then decodes the data signal received from the other source. For this wireless-powered two-way relay system, we propose two secure relay protocols based on power splitting and time switching techniques. The two protocols are power splitting-based two-way relaying (PS-TWR) and time switching-based two-way relaying (TS-TWR), in which the relay, respectively, controls the power splitting ratio ( ρ ) and time switching ratio ( α ), in order to achieve a balance between the data receiving and the energy harvesting. The optimal values of ρ and α for each protocol are found analytically to maximize the minimum guaranteed secrecy capacity (CS-min) considering multiple eavesdroppers in high signal-to-noise ratio environments. Numerical results show that both the PS-TWR and TS-TWR protocols using the optimized values of ρ and α achieve the near-optimal CS -min no matter how many eavesdroppers exist anywhere. Comparisons of the two protocols in various scenarios also show that PS-TWR achieves better CS -min than TS-TWR because PS-TWR inherently has a shorter vulnerable time for eavesdropping than TS-TWR.

Original languageEnglish
Pages (from-to)162-174
Number of pages13
JournalIEEE Transactions on Information Forensics and Security
Volume14
Issue number1
DOIs
StatePublished - Jan 2019

Keywords

  • Energy harvesting
  • physical layer security
  • power splitting
  • secrecy capacity
  • time switching
  • two-way relay

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