Abstract
In this paper, we investigate an energy-harvesting cooperative communication network, which comprises of a source, a destination, and multiple decode-and-forward (DF) relays in the presence of multiple passive eavesdropper (Es). Es attempt to intercept confidential information transmissions from the source to destination via DF relays. In this network, all the DF relays harvest energy from radio-frequency (RF) signals of a source through time-switching receivers. In order to improve the physical layer security of energy-harvesting cooperative communication networks, we propose a best relay selection (BRS) scheme, where the “best” relay is chosen to assist the source-destination transmission. For the purpose of comparison, we consider the classic direct transmission (DT) and equal relay selection (ERS) as benchmark schemes. We derive the exact closed-form expressions of outage probability (OP) and intercept probability (IP) for the ERS and BRS schemes over Rayleigh fading channels. Besides, the security-reliability tradeoff (SRT) is analyzed as a metric to evaluate the tradeoff performance of the proposed BRS scheme. Numerical results show that the SRT of the BRS scheme consistently outperforms that of the ERS scheme, which demonstrates the advantage of our proposed scheme against eavesdroppers. Besides, it is verified that total error rate (TER) defined as the sum of OP and IP can be minimized for both the ERS and BRS schemes through changing the time allocation factor between information transmission and energy harvesting phases. Moreover, there is a best energy conversation efficiency to obtain a maximal SRT value of the ERS and BRS schemes. In addition, as the number of DF relays increases, the SRT of BRS scheme improves notably, while that of ERS scheme remains unchanged. And as the number of Es increases, the SRT of both the ERS and BRS schemes become worse.
Highlights
Nowadays, energy harvesting (EH) emerges as a promising technique to deal with the scarcity of energy resources and prolong the lifetime of wireless networks, especially in hazardous environments where replacing or recharging batteries is infeasible or costly for sensors embedded inside the human body or in building structures, as well as wireless mobile devices that are not accessible [1]–[4]
Motivated by the above research, we explore physical layer security for an EH cooperative communication network consisting of a source, a destination, and multiple decodeand-forward (DF) relays, which are capable of collecting the energy from RF signal of the source
NUMERICAL RESULTS AND DISCUSSIONS This section presents the numerical results of the outage probability (OP) and intercept probability (IP) as well as security-reliability tradeoff (SRT) for the equal relay selection (ERS) scheme and best relay selection (BRS) scheme under the Rayleigh fading channels
Summary
Energy harvesting (EH) emerges as a promising technique to deal with the scarcity of energy resources and prolong the lifetime of wireless networks, especially in hazardous environments where replacing or recharging batteries is infeasible or costly for sensors embedded inside the human body or in building structures, as well as wireless mobile devices that are not accessible [1]–[4]. References [28]–[31] combined cooperative jamming and energy-harvesting relay to improve the physical layer security performance. Motivated by the above research, we explore physical layer security for an EH cooperative communication network consisting of a source, a destination, and multiple decodeand-forward (DF) relays, which are capable of collecting the energy from RF signal of the source. SYSTEM MODEL Fig. presents a system model of the energy-harvesting cooperative communication network consisting of a source (S), a destination (D), Nr DF relays equipped with energy harvesters, and Ne passive eavesdroppers which may overhear encrypted data transmissions from S to D via relay nodes independently. In Fig., T is the duration of EH and information transmission from S to D, and α is the time allocation ratio for relays harvesting energy from the source signal (0 ≤ α ≤ 1). SECURITY PERFORMANCE ANALYSIS OF THE ERS SCHEME AND THE BRS SCHEME we analyze the OP and IP as well as the SRT of the ERS scheme and BRS scheme
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