Adaptive Secure Transmission for Wireless Powered Communication Networks

• 来源期刊: 中国通信（英文版）
• 年，卷（期）: 2021,（3）
• 所属期刊栏目: NETWORKS & SECURITY
• 页码范围: 155-173
• 页数: 19页
• 语种: 英文

摘要

This paper investigates secure transmis-sion in a wireless powered communication network (WPCN) with an energy harvesting (EH) source con-figured with multiple antennas. In the WPCN, the EH source harvests energy from the radio frequency (RF) signals broadcasted by a power beacon (PB), and purely relies on the harvested energy to commu-nicate with the destination in the presence of pas-sive eavesdroppers. It is noteworthy that the RF-EH source is equipped with a finite energy storage to ac-cumulate the harvested energy for the future usage. Moreover, due to energy-constraint and complexity-limitation, the multi-antenna source is only config-ured with a single RF-chain. To enhance the secu-rity for the WPCN, we propose two adaptive trans-mission schemes, i.e., energy-aware transmit antenna selection (EATAS) and energy-aware differential spa-tial modulation (EADSM). According to the energy status and the channel quality, the source adaptively decides whether to transmit confidential information or harvest RF energy. To evaluate the secrecy perfor-mance of the proposed schemes, we first study the evo-lution of the energy storage, and then derive the an-alytical expressions of connection outage probability (COP), secrecy outage probability (SOP) and efficient secrecy throughput (EST). Numerical results demon-strate that our proposed schemes outperform the exist-ing schemes, i.e., time-switching based TAS (TS-TAS) and accumulate-then-transmit (ATT). And, increasing the transmit power of the PB or the capacity of the source's energy storage is helpful to improve the se-crecy performance. Moreover, there exists an optimal transmission rate for each proposed scheme to achieve best secrecy performance.