# Performance Evaluation of a Full-Duplex Relaying-Enabled Satellite Sensor Network
## 1 Introduction  
### Satellite Systems  
Sensor nodes are commonly involved in an extensive range of applications in environmental sensing, remote health monitoring, environmental monitoring and target tracking [1; 2]. Due to the potential in providing wide coverage and high transmission rate, satellite sensor networks have been regarded as an effective approach to provide telecommunication and multimedia services for users who are separated far away, especially when the line-of-sight (LoS) link is unavailable because of the masking effect [3; 4; 5]. Satellite relaying is known as a basic type for communication, tracking and data exchange for future integrated satellite-terrestrial scenarios [6]. Generally, the basic architectures of satellite relaying includes two widely adopted schemes, namely, amplify-and-forward (AF) and decode-and-forward (DF) relay protocols [7]. The DF satellite relaying performs on-board processing to demodulate the received signals over the uplink, and then remodulate signals over the downlink [8]. The AF satellite relaying, which amplifies the signal transmitted from source and forwards it to the destination with fixed or channel state information (CSI) assisted gain, is of particular interest due to implementation simplicity [9; 10]. Recently, due to the fact that future wireless networks require enhanced spectral efficiency to support the increasing demand of access and application services, the full-duplex (FD) techniques have received considerable attention as promising candidates for its capability in alleviating the spectrum shortage [11; 12]. FD transmission mode has been widely applied in a variety of wireless systems,including vehicular networks, device-to-device (D2D) networks and multiple antenna networks [13]. However, traditional transmission scenarios in satellite sensor systems were all assumed to be in a half-duplex (HD) mode, which resulted in spectral deficiency and low on-board resource utilization. To meet the increasing demand for higher throughput in future satellite networks, several potential techniques have been considered to improve the spectral efficiency in satellite communications, among which, full-duplex (FD) mode has been considered as a promising technique since it can afford simultaneously transmission and reception on the same carrier frequency [14; 15]. Until now, the work in [14] presented initial considerations on the coexistence of simultaneous transmission and reception in full-duplex satellite relaying, and justified the effectiveness of analog and digital cancellation together with the passive suppression in achieving an enhanced self-interference (SI) cancellation. The authors of [15] modeled and analyzed the signal and SI components in the context of in-band FD satellite relaying, which illustrated the feasibility and perspective of FD-enabled satellite relaying from the technical point of view. Moreover, the implementations of joint analog and digital cancellations with respect to the on-board residual SI for FD satellite relaying was explored in [16]. Although the aforemention works established fundamentals and reviewed the potential applications of FD in satellite communication systems, no contributions have been dedicated to analyzing the key performance metrics of full-duplex satellite relaying systems; thus, its performance gains and superiority over the conventional HD mode also remained unknown. In this paper, we investigate the performance of the satellite sensor networks with full-duplex relaying under residual SI. Specifically, the main contribution presented in this work can be summarized in the following aspects:  
* We first develop an FD-enabled framework for satellite relaying systems by applying the standard recommendations and considering practical antenna geometries, configurations, and channel characteristics. The new diagram of this paper establishes the foundation for system performance evaluation, which can be viewed as a general and extensively applicable model for various scenarios.