Shadowed Rician Fading Research Articles

Hierarchical Maritime Radio Networks for Internet of Maritime Things

Despite the potential benefits of a maritime Internet of Things, a number of issues hinder its realization, including the need for wide area coverage and cost-effectiveness. Toward these needs, a model is first presented for uplink maritime radio communications that hierarchically employ Wi-Fi and cellular links for data transmission from marine user equipments (MUEs) on a ship to a cellular base station with distributed antennas (DAs) along a coastline. Then, the performances are evaluated given in terms of average data rate and outage probability in the hierarchical maritime radio networks. When evaluating the performances, heterogeneous channel characteristics of the hierarchical networks are taken into account in which Rayleigh fading is considered for the MUE-ship links, whereas shadowed-Rician fading is considered for the ship-DA links. Moreover, the effects due to various transmission errors that can be occurred at different communication layers are reflected in determining the quality of service (QoS) requirements of a ship. With the help of authors' analysis, an antenna selection algorithm is proposed under which the minimum size of a service cloud can be found to support the QoS requirements of MUEs with a ship. The numerical evaluations demonstrate the validity of the proposed algorithm.

Physical Layer Security of Multiuser Satellite Communication Systems With Channel Estimation Error and Multiple Eavesdroppers

This paper investigates the physical layer security (PLS) for the transmission of confidential information over satellite communication systems under unified framework. The generalized shadowed-Rician (SR) fading is utilized to model the satellite channel, and multiple legitimate users are served to cooperatively receive the broadcast signal with a cluster of unauthorized eavesdroppers. In particular, the channel estimation error (CEE) is considered for both the legitimate user and eavesdropping links. Based on the practical channel modeling, we derive the closed-form expressions for the probability of strictly positive secrecy capacity (PSPSC), secrecy outage probability (SOP), and average secrecy capacity (ASC) of the considered satellite communication system in the presence of imperfect channel estimation (ICE), which can provide efficient methods to evaluate the impacts of various propagation parameters on the secrecy performance. In order to obtain further insights into the key parameters on the secrecy performance at high signal-to-noise ratios (SNRs), the asymptotic expressions of the SOP and ASC are also derived. Monte Carlo simulation results are provided to verify the correctness of our performance analysis.

Performance Analysis of NOMA-Based Cooperative Spectrum Sharing in Hybrid Satellite-Terrestrial Networks

In this paper, the performance of non-orthogonal multiple access (NOMA) based cooperative spectrum sharing in hybrid satellite-terrestrial networks (HSTNs) is investigated, where the primary satellite network recruits the secondary terrestrial network as a cooperative relay. To improve the fairness and spectrum utilization under cooperative spectrum sharing (i.e. overlay paradigm of cognitive radio), the NOMA power allocation profile is determined by instantaneous channel conditioning at the second temporal phase. The closed-form outage probability and approximated ergodic capacity expressions for the primary user (PU) and the secondary user (SU) are derived by decode-and-forward (DF) relay protocols, where the generalized Shadowed-Rician fading and Nakagami-m fading are considered for satellite links and terrestrial links, respectively. Simulation results are conducted for validation of the theoretical derivation and analysis of the impact of key parameters, and prove the superiority of NOMA comparing to conventional orthogonal multiple access (OMA) schemes on cooperative spectrum sharing in HSTNs. Besides, the fairness analysis between the PU and the SU is introduced by Jain's fairness index (JFI).

Outage Performance of NOMA-Based Cognitive Hybrid Satellite-Terrestrial Overlay Networks by Amplify-and-Forward Protocols

In this paper, we investigate the outage probability (OP) performance of amplify-and-forward (AF) cognitive hybrid satellite-terrestrial overlay networks (CHSTONs) with the non-orthogonal multiple access (NOMA) scheme, in which half-duplexing terrestrial secondary networks cooperate with a primary satellite network for dynamic spectrum access. In order to improve the fairness of overlay paradigm, a NOMA-based power allocation profile is determined by instantaneous channel conditions. Considering the generalized shadowed-Rician fading for satellite links and Nakagami-$m$ fading for terrestrial links, we derive the closed-form OP expressions for both the primary and secondary users. Then, the asymptotic OP expressions at the high signal-to-noise ratio (SNR) regime are also obtained to evaluate the achievable diversity order and coding gain. Finally, the numerical simulations are provided to validate the theoretical results as well as the superiority of the NOMA scheme in CHSTONs and proclaim the effect of key parameters on the performance of the NOMA users, such as fading configurations and the power split factor.

Outage Performance of UAV-Assisted Relaying Systems With RF Energy Harvesting

In this letter, we propose an UAV-based relaying system with energy harvesting functionality. In particular, we assume that this system is operated in urban communication environments, where the channel between the UAV and the land destination is modeled as shadowed-Rician fading or shadowed-Rayleigh fading. Based on this setting, outage probability analysis for different urban environment parameters is derived. Finally, Monte Carlo simulations are conducted to verify the accuracy of our analytical results.

Secrecy Performance of Satellite Wiretap Channels With Multi-User Opportunistic Scheduling

This letter investigates the secrecy performance of a satellite wiretap channel with multi-user opportunistic scheduling. By considering some practical effects, such as satellite multi-beam pattern and path loss, and assuming that the satellite channel undergoes Shadowed-Rician fading with the channel parameters being integer, we derive closed-form expressions of the probability of non-zero secrecy capacity, the secrecy outage probability and the average secrecy capacity for the satellite wiretap channels. Numerical results confirm the correctness and effectiveness of the secrecy performance analysis.

Outage Analysis of Cognitive Hybrid Satellite-Terrestrial Networks With Hardware Impairments and Multi-Primary Users

This letter investigates the effects of practical hardware impairments on a cognitive hybrid satellite-terrestrial networks (CHSTN) with multiple primary users (PUs). The widely employed shadowed-Rician fading distribution is adopted to model the satellite-terrestrial channel. CHSTN can provide comprehensive wireless coverage as well as enhanced spectrum resource usage by considering the requirements of both spectrum efficiency and reliability. Specifically, we derive the closed-form expression of the outage probability (OP) for the considered system in the presence of interference power constraints imposed by multiple adjacent terrestrial PUs. To gain further insights at high signal-to-noise ratios, the asymptotic expression for the OP is also derived. Numerical results confirm the correctness and effectiveness of our performance analysis.

Exact and asymptotic ergodic capacity analysis of the hybrid satellite–terrestrial cooperative system over generalised fading channels

In this study, the authors analyse the ergodic capacity of the downlink channel in a hybrid satellite–terrestrial cooperative system. The satellite link experiences shadowed Rician fading and the terrestrial link follows Rayleigh fading. Using the moment generating function-based approach, they derived the formulae for the ergodic capacity with the amplify-and-forward protocol or the decode-and-forward protocol. Moreover, the asymptotic expression for the ergodic capacity at a high signal-to-noise ratio is derived, and the system multiplexing gain is also obtained. Using the asymptotic results, they propose a simple relay selection strategy, which only requires the knowledge of channel statistics. Monte Carlo simulations are provided to confirm the analytical results, and to illustrate the effect of different factors, in terms of the number of relays, channel conditions, and the cooperative protocol, on the ergodic capacity. Numerical results show that the analytical results are highly accurate in the single relay scenario and have low computational complexity in the multi-relay scenario. In addition, the proposed relay selection strategy achieves low overhead in the price of a little performance degradation.

Performance analysis of shadowed-Rice fading channel with cooperative spectrum sensing

ABSTRACTIn this paper, the performance analysis of wireless communication system over shadowed-Rice (SR) composite fading channel has been investigated and analysed. The unified analytical expressions of the average symbol error probability (ASEP) for several coherent and non-coherent modulation schemes separately with different constellation sizes are derived for composite fading channel under two different fade mitigation methods, with maximal ratio combining (MRC) microdiversity (Method 1) and MRC applied over the composite fading channel (Method 2). Furthermore, an asymptotic analysis is carried out and a closed-form expression of the ASEP with Method 2 is presented. Analytical expressions of the corresponding average probability of energy detection (PD) are formulated for both the methods. Finally, the derived PD expression is utilised to analyse the performance of cooperative system assuming erroneous feedback channel. Analysis of optimisation of detection threshold as well as number of cognitive users to minimise the total error rate is also carried out. The closed-form expressions are validated by comparing them with exact numerical results and Monte Carlo simulation.

Physical layer secrecy performance analysis of multi-user hybrid satellite-terrestrial relay networks

This paper investigates the secrecy performance of a downlink multi-user amplify-and-forward hybrid satellite-terrestrial relay network (HSTRN) with opportunistic scheduling of terrestrial users. By considering Shadowed-Rician fading for satellite link and Nakagami-m fading for terrestrial links, we derive accurate and asymptotic expressions for secrecy outage probability (SOP). Based on the asymptotic behaviour of SOP expression at high signal-to-noise ratio regime, we illustrate practical insights on the achievable diversity order of the system. Subsequently, we also deduce the expression for probability of non-zero secrecy capacity. Finally, numerical and simulation results are provided to vindicate our analysis and to show the impact of various key channel/system parameters such as shadowing severity and number of users on the physical layer secrecy performance of HSTRNs.

Ergodic Capacity of Multiuser Hybrid Satellite-Terrestrial Fixed-Gain AF Relay Networks With CCI and Outdated CSI

In this paper, we investigate the ergodic capacity (EC) of a downlink multiuser hybrid satellite-terrestrial amplify-and-forward relay network (HSTAFRN) using a fixed-gain relaying protocol in the presence of co-channel interference. Herein, we employ opportunistic scheduling of terrestrial users by considering outdated channel state information over Nakagami- m fading channels of pertinent links. By deploying multiple antennas at the satellite, we derive a novel and accurate analytical expression of the achievable EC by making use of the complementary moment generating function transform. More importantly, we carry out the EC analysis under both uncorrelated and correlated shadowed-Rician fading channels of satellite links. Our numerical and simulation results attest the accuracy of the proposed analysis and reveal the impact of various system/channel parameters on EC of the considered HSTAFRN.

Bivariate Rician Shadowed Fading Model

In this paper we present a bivariate Rician shadowed fading model where the shadowing is assumed to follow a Nakagami-$m$ distribution. We derive exact expressions involving a single integral for both the joint probability density function (PDF) and the joint cumulative distribution function (CDF) and we also derive an exact closed-form expression for the moment generating function (MGF). As a direct consequence we obtain a closed-form expression for the power correlation coefficient between Rician shadowed variables as a function of the correlation coefficient between the underlying variables of the model. Additionally, in the particular case of integer $m$ we show that the PDF can be expressed in closed-form in terms of a sum of m Meijer G-functions of two variables. Results are applied to analyze the outage probability (OT) of a dual-branch selection combiner (SC) in correlated Rician shadowed fading and the evaluation of the level crossing rate (LCR) and average fade duration (AFD) of a sampled Rician shadowed fading envelope.

Performance Analysis of Multi-Antenna Multiuser Hybrid Satellite-Terrestrial Relay Systems for Mobile Services Delivery

Satellite communication systems need to be integrated with emerging cooperative relaying techniques to provide seamless connectivity and high-speed broadband access for mobile users in future wireless networks. In this paper, we study a multi-antenna multiuser hybrid satellite-terrestrial relay network (HSTRN) employing opportunistic user scheduling with outdated channel state information (CSI) and amplify-and-forward relaying with co-channel interference (CCI). By adopting Shadowed-Rician fading for satellite links and Nakagami- ${m}$ fading for terrestrial links, we derive novel and accurate expressions for outage probability and ergodic capacity of the proposed HSTRN, and further examine its achievable diversity order. More importantly, we conduct the performance analysis by taking both uncorrelated and correlated Shadowed-Rician fading channels into account and show that the antenna correlation at the satellite does not affect the overall system diversity order. Our derived analytical expressions provide efficient tools to characterize the impact of CCI, outdated CSI, and antenna correlation on the system performance of HSTRN with an arbitrary number of satellite antennas, number of interferers, number of users, and integer values of the per-hop fading severity parameters. Our results provide useful guidelines in the design of futuristic HSTRNs for satellite mobile communications.

Cognitive Relaying Cooperation in Satellite-Terrestrial Systems With Multiuser Diversity

This paper investigates the outage performance of an overlay multiuser hybrid satellite-terrestrial spectrum sharing system. Herein, we exploit both direct and relay links from a primary satellite source to multiple terrestrial users with the coexistence of a secondary transmitter–receiver pair on the ground. Based on an overlay approach, the secondary transmitter provides an amplify-and-forward-based relay cooperation to the primary satellite network that employs opportunistic scheduling of multiple users. The underlying user scheduling strategy is based on satisfying the criterion of minimal outage probability (OP) for the primary network and, eventually, exploring more opportunities of the spectrum sharing for the secondary terrestrial network. By considering the widely adopted Shadowed-Rician fading model for the satellite links while the Nakagami- $m$ fading model for the terrestrial links, we derive the analytical expressions for the OP of the primary satellite network and the secondary terrestrial network and further highlight the corresponding achievable diversity orders. We also examine the impact of power splitting factor for spectrum sharing between primary and secondary networks.

Secrecy performance of hybrid satellite‐terrestrial relay networks in the presence of multiple eavesdroppers

This study investigates the secrecy performance of a hybrid satellite-terrestrial relay network (HSTRN) in the presence of multiple eavesdroppers, where the satellite link undergoes Shadowed-Rician fading, while the terrestrial link follows Rayleigh fading. The authors suppose the direct link between the satellite and the intended user is unavailable due to heavy shadowing and adopt a multi-antenna relay using either a decode-and-forward (DF) or an amplify-and-forward (AF) protocol to assist the transmission. By employing perfect channel state information of each link at the relay, the authors first apply receive maximal ratio combining beamforming (BF) and transmit zero-forcing BF schemes to obtain the output signal-to-noise ratios (SNRs) of the intended user and eavesdroppers. Then, based on the Meijer-G function and the moment generating function, the authors derive the analytical expressions of the ergodic secrecy rate for the considered HSTRN for both DF and AF protocols. Finally, Monte-Carlo simulations are conducted to validate the theoretical performance analysis and reveal the effects of certain representative parameters on the system secrecy performance.

Relay selection‐based hybrid satellite‐terrestrial communication systems

The problem of relay selection in amplify-and-forward (AF)-based hybrid satellite-terrestrial cooperative communication systems is considered. A partial relay selection scheme is studied in which satellite selects a relay earth station (ES) among multiple relay ESs (situated on ground) on the basis of maximum instantaneous signal-to-noise ratio (SNR). Satellite-relay ESs are assumed to follow Shadowed-Rician fading, whereas relay ESs-destination ES links (terrestrial links) are assumed to follow Nakagami- m distribution. First, the cumulative distribution function and probability density function (PDF) of the maximum instantaneous SNR of satellite-relay ESs links are derived; then by using this PDF, the expression of moment generating function (MGF) of the received instantaneous SNR at destination ES is obtained. The average error performance of the considered system with the proposed relay ES selection is derived in terms of Meijer- G functions by using MGF approach. In order to get the diversity order of the relay ES selection-based AF scheme, the asymptotic PDF of the considered scheme is derived, and then by using this asymptotic PDF, the analytical diversity order of the system is obtained. It is demonstrated by the analysis and simulation that the performance of the AF-based hybrid satellite-terrestrial communication systems can be significantly improved by deploying more relay ES at the ground in between satellite and destination ES.

Performance Analysis of Overlay Spectrum Sharing in Hybrid Satellite-Terrestrial Systems With Secondary Network Selection

In this paper, we study a hybrid satellite-terrestrial spectrum sharing system (HSTSSS) in which multiple terrestrial secondary networks cooperate with a primary satellite network for dynamic spectrum access. For complexity-aware HSTSSS design, we propose an amplify-and-forward-based overlay spectrum sharing protocol using partial and opportunistic secondary network selection schemes. The secondary network selection aims to minimize the outage probability of the primary satellite system and, thereby, to explore spectrum sharing opportunities. With the overlay approach, the selected secondary network allocates part of its power to relay the satellite signal and utilizes the remaining power to transmit its own signal. Considering Shadowed-Rician fading for satellite links, and Nakagami- ${m}$ as well as Rician fading for terrestrial links, we derive closed-form expressions for the outage probability of both primary and secondary networks, and examine their achievable diversity orders. Numerical and simulation results validate our analysis and highlight the performance gains of the proposed schemes for an HSTSSS with and without a direct satellite primary communication link.

Ergodic Channel Capacity Analysis of Downlink in the Hybrid Satellite-Terrestrial Cooperative System

In this paper, the ergodic channel capacity of the downlink is analyzed for a hybrid satellite-terrestrial cooperative system, which consists of a satellite (the source), a mobile terminal (the destination), and several gap fillers (the relays) located at the ground. The links between the satellite and the relays and the link between the satellite and the destination experience independent shadowed Rician fading, and the links between the relays and the destination experience Rayleigh fading. The maximal ratio combining technique is used at the destination to combine the direct signal received from the satellite and the relayed signals from relays with different cooperative protocols, namely amplify-and-forward (AF) and decode-and-forward (DF). The moment generating function (MGF)-based approach is adopted to derive the closed-form expressions of the ergodic downlink channel capacity of the hybrid satellite-terrestrial cooperative system. The numerical results are compared with Monte Carlo simulations and numerical results calculated with the existing analytical expressions. Comparison results show that the analytical expression derived with the MGF-based approach can achieve a higher accuracy in the low signal-to-noise ratio (SNR) regime for the single relay scenario, and significantly reduce the computational complexity with a little loss of accuracy for multiple relays scenario. On the other hand, the ergodic downlink channel capacity of the hybrid satellite-terrestrial DF cooperative system is generally higher than that of the AF cooperative system. Moreover, the ergodic channel capacity of the hybrid satellite-terrestrial cooperative system decreases as the number of participating relays increases, which can be overcome using the best relay selection strategy. In addition, the ergodic downlink channel capacity of the hybrid satellite-terrestrial cooperative system increases when the channel condition of the link between the satellite and the relay goes better, and is larger than that of the no relay land mobile satellite system when the transmitted SNR is below a certain value.

Performance analysis of dual-hop satellite relay networks with hardware impairments and co-channel interference

In this paper, we investigate the impact of hardware impairments on the outage performance and the instantaneous capacity of dual-hop decode-and-forward (DF) satellite relay networks in the presence of co-channel interference. Specifically, the exact closed-form expression for the outage probability and the analytical expression for the instantaneous capacity of the system are derived over a shadowed-Rician fading channel, which provides a fast means to evaluate the impact of hardware impairments on the system performance. Our results demonstrate that the outage floor occurs and the capacity upper bound appears when the hardware impairments exist. In addition, simulation results were provided to verify the correctness of the analytical results.

A Novel Beamforming and Combining Scheme for Two-Way AF Satellite Systems

We propose a novel beamforming and combining scheme for a two-way amplify-and-forward (AF) satellite system. Exchange of the data in between two multiple-antenna-based Earth stations (ESs) via a single-antenna-based satellite is performed. The transmitting ES uses beamforming for transmission of the data, and the receiving ES utilizes the combining vector for detecting the transmitted signal. By using maximum eigenvalue criterion, the beamforming and combining vectors are calculated. The satellite channels (uplink and downlink) are assumed to be shadowed Rician (SR) fading. First, we assume independent and identically distributed (i.i.d.) SR fading channels and derive the probability density function (pdf) of maximum eigenvalue to obtain the expression of moment-generating function (mgf). The closed-form expression for the symbol error rate (SER) of the scheme for $M$ - ary phase-shift keying (MPSK) is obtained by using an mgf-based approach. The diversity order of the studied scheme is also derived by exploiting the asymptotic property of the Meijer G-function. Next, we consider correlated SR fading channels and derive expressions of SER and diversity order. It is shown by simulations that the proposed scheme outperforms the existing beamforming and combining based scheme in two-way AF satellite systems. It is concluded on the basis of the diversity order analysis that the diversity of the proposed scheme linearly depends upon the minimum of the number of antennas of two ESs. Furthermore, it is also shown by simulation and analysis that correlation does not affect the diversity order of the considered scheme.