# Performance Analysis of Two-Way Satellite-Terrestrial Relay Network with SWIPT
###### Abstract  
In this paper, we investigated the performance of a two-way satellite-terrestrial DF relay network with asymmetric simultaneous wireless information and power transfer (SWIPT). In particular, selective physical-layer network coding (SPNC) was employed in the proposed network, improving the throughput performance. We derived the expressions of system average end-to-end throughput and single node detection (SND) occurrence probability. Furthermore, to observe the effects of the power splitting (PS) coefficient on the energy efficiency performance, the expressions of energy harvested in the physical-layer network coding (PNC) and SPNC protocol were also derived. Finally, theoretical analyses and Monte Carlo simulation results are presented to show: (i) SPNC protocol outperforms the conventional PNC protocol in the two-way satellite-terrestrial relay network with SWIPT in infrequent light shadowing (ILS), average shadowing (AS), and frequent heavy shadowing (FHS) Shadowed-Rician fading channels; (ii) as the channel state gets worse, SPNC protocol can achieve more performance improvement than PNC protocol; (iii) as the PS coefficient increases, the average end-to-end throughput performance increases progressively, and the average energy efficiency performance increases progressively within a certain range, while decreasing in the others. s _sensors_  
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[PERSON]; [PERSON]; [PERSON] Performance Analysis of Two-Way Satellite-Terrestrial Relay Network with SWIPT. _Sensors_**2021**, _21_, 4303. [[https://doi.org/10.3390/s21134303](https://doi.org/10.3390/s21134303)]([https://doi.org/10.3390/s21134303](https://doi.org/10.3390/s21134303))  
Academic Editor: [PERSON]  
Received: 10 May 2021  
Accepted: 19 June 2021  
Published: 23 June 2021  
**Published:**  
**Sublayer:**  
**Sublayer:**  
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operation is replaced by single node detection during the second time slot of conventional PNC. In [8], the authors derived upper bounds in closed-form for average BERs of the SPNC scheme over Rayleigh fading channels. In [9], the exact BER analysis of PNC for two-way relay channels was presented by the authors. In [10], the effect of hardware impairments on a two-way satellite-terrestrial relay network was analyzed. An opportunistic relay selection scheme was employed in a two-way satellite multi-terrestrial cooperative network in [11]. In [12], the satellite-terrestrial cooperative network was analyzed. The performance of a distributed space-time coding-based hybrid satellite-terrestrial cooperative system with a single fixed terrestrial relay was investigated. However, the lifetime of a two-way satellite-terrestrial network is limited by the battery power of the terrestrial mobile user. To overcome the problem of battery limitation, we can introduce energy harvesting techniques to extend the system's lifetime. The energy-constrained device can harvest energy from a portion of the received signal without affecting the communication performance. The author proposed SWIPT in [13], where the receiver simultaneously executes information decoding and energy harvesting. Considering the structure of the wireless receiver, [14] proposed two kinds of effective working modes: time switching (TS) mode and PS mode. PS mode uses one portion of the received signal power for information decoding and the remaining portion for energy harvesting from the perspective of power allocation in [15; 16]. From the perspective of time slot allocation, TS mode divides a communication period into two portions in [17; 18], one of which is used for information decoding. The remaining portion is used for energy harvesting. Much research work has been done on relay energy harvesting scenarios [19; 20; 21]. In [22], an asymmetric energy harvesting model was discussed with energy efficiency (EE) precoding design in MIMO two-way relay network. EE was defined as the ratio of total energy consumption and information rate in green communications in [23; 24; 25].