Land Mobile Satellite Communication Research Articles

Physical Layer Security in Interference Limited Land Mobile Satellite Communication Systems: Safeguarding Data Transmission

This paper focuses on evaluating the secrecy performance of a downlink land mobile satellite (LMS) system. The system faces the challenge of providing secure communication between a satellite and a legitimate user while an eavesdropper is present on the ground. Additionally, co-channel interference signals at the user's destination are considered. To address these issues, the study proposes a novel approach that utilizes Shadowed-Rician fading channels for satellite links and Nakagami-m fading for interfering terrestrial links. The main objective is to enhance the physical layer security of Interference-Limited Land Mobile Satellite Communication Systems. The approach incorporates advanced signal processing, beamforming, and artificial noise techniques to effectively manage interference. Encryption, authentication mechanisms, and intelligent power control strategies are implemented to protect transmitted data and optimize signal strength while reducing the risk of interception by potential eavesdroppers. Through comprehensive simulations, the proposed approach is thoroughly evaluated, demonstrating its effectiveness in achieving improved secrecy performance and increased resilience against security threats. The findings highlight the potential for its application in secure satellite communication systems operating in interference-constrained environments.

Performance Evaluation of SSK Modulation Over Shadowed-Rician Land Mobile Satellite Links

We investigate the performance of satellite communication systems acquiring the space shift keying (SSK) modulation technique over shadowed-rician (SR) land mobile satellite (LMS) link. Specifically, we discuss the analytical performance of the considered system over independent and identically distributed SR fading channels in terms of symbol error rate (SER), diversity order, and average capacity. The SER of the considered set-up is derived by utilizing moment generating function (MGF) expression over the SR fading LMS communication links. The analytical diversity order of the scheme is derived by using SER expression. We consider the effect of elevation angles on the SER performance, diversity order, and channel capacity of the considered SSK-assisted satellite communication system. As observed from simulation and analytical results, the performance of the considered set-up can be raised by improving elevation angles. Further, a closed-form expression of the average capacity of the SSK assisted satellite communication system is also derived. It is shown through simulation and analysis that the fading conditions and elevation angle does not affect the diversity order of the system, but it adversely acts on the SER performance and average capacity of the system.

A Comprehensive Review of Channel Modeling for Land Mobile Satellite Communications

As demands on the network continue to grow, it is increasingly important to upgrade the existing infrastructure in order to offer higher bandwidth and service level guarantees to users. Next generation networks (NGNs) represent a fully IP-based architecture that is able to support different technologies. In this context, the satellite networks are considered a fundamental part for future hybrid architectures. In this scenario, knowing satellite channel propagation characteristics in order to be able to design a communication system to respond to new user needs is of fundamental importance. Many papers in the literature show channel models in different satellite scenarios both for fixed and mobile applications; however, to the best of our knowledge, nobody presents an overview on different satellite models based on Markov chains. This paper wants to present a comprehensive review of the most recent developments in satellite channel communications related to mobile services and, in particular, for the land mobile satellite systems. The work presents all different types of Markov models, from single-state to multi-state models, that have been proposed in the literature from the early 1980s.

Cooperative jamming in downlink satellite network with hardware impairments

AbstractIn this article, a land mobile satellite communication network with an external jammer to fight against the eavesdropper is investigated, where the hardware impairments are introduced to make the analyses more practical. It is worth noting that three jamming schemes, that is, the Gaussian noise jamming, the friendly jamming, and the scheme without jamming, are taken into account to explore the effect of the jammer comprehensively. The secrecy metrics such as the connectivity outage probability (COP), the security outage probability, and the secrecy throughput (ST), are derived for the passive eavesdropping scenario, while the ergodic secrecy capacity is analyzed for the active eavesdropping scenario. Moreover, to get intuitive insight from the closed‐form expressions, the asymptotic ST and the asymptotic COP under the condition of high signal‐to‐noise ratio are also considered. Finally, all the derivations are validated by Monte Carlo simulations, and the effects of different parameters on the performance of the network are analyzed.

Multi-Dimensional Polarized Modulation for Land Mobile Satellite Communications

In this article, a novel multiple-input multiple-out (MIMO) transmission scheme, called generalized polarized enhanced spatial modulation (GPESM), is proposed for dual-polarized land mobile satellite (LMS) communications. We first introduce the enhanced spatial modulation (ESM) technique for dual-polarized LMS communications, in which polarization dimension, spatial dimension and multiple signal constellations are used to transmit information and obtain substantial performance gain. Meanwhile, the theoretical upper bound for the average bit error probability (ABEP) of the proposed GPESM scheme is derived. In order to further improve the reliability of the system, we also propose two novel power allocation (PA) algorithms for GPESM system, which are the optimization-driven approximated max-min distance (AMMD)-based PA algorithm and the data-driven deep neural network (DNN)-based PA algorithm. To achieve an enhanced spatial diversity gain, we consider to apply a reconfigurable intelligent surface (RIS) to the GPESM system as a relay to assist in transmitting information. In this way, the user can receive the information transmitted by the satellite on one hand, and the information sent by the satellite via the RIS relay on the other hand. We also extend the above-mentioned two PA algorithms to the RIS-assisted GPESM systems. Our simulation results show that the RIS-assisted GPESM systems are capable of obtaining high bit error rate (BER) performance gain (up to 10 dB) compared to the standard GPESM system and two PA algorithms can further improve the performance to the systems.

Reliability and Security Performance Analysis of Hybrid Satellite-Terrestrial Multi-Relay Systems With Artificial Noise

Land mobile satellite communication and physical layer security are considered as the promising paradigms in beyond 5G networks. In this paper, we establish the multi-relay hybrid satellite-terrestrial systems (HSTSs) with artificial noise (AN) to investigate the reliability and security, in which the satellite sends signals to the terrestrial destination through multiple decode-and-forward relays and there exists an eavesdropper trying to overhear the useful information. In order to improve the overall system performance, two relay selection (RS) schemes: i) optimal relay-receiver pair selection (ORRPS) and ii) suboptimal relay selection (SRS) are considered. ORRPS selects an optimal relay-receiver pair and an AN signal to maximize the corresponding signal-to-interference-plus-noise ratios of ${R_{k}} \to D\left ({{R_{k} \to E} }\right)$ and the SRS refers to selecting a relay that optimize the instantaneous channel gain ${\left |{ {{h_{R_{k}D}}} }\right |^{2}}\left ({{{{\left |{ {{h_{R_{k}E}}} }\right |}^{2}}} }\right)$ among $K$ relays, with the traditional round-robin selection scheme as a benchmark for comparison. Furthermore, the exact closed-form analytical expressions of outage probability (OP) and intercept probability (IP) under different RS schemes are derived for AN and non-AN conditions. To obtain more insights, the asymptotic analysis for high signal-to-noise-ratio regime is carried out. Based on the asymptotic analysis of OP, the diversity orders of the HSTSs are obtained. The numerical results and theoretical analysis shown that: i) The reliability of TRRS scheme is the worst among the three RS schemes, and the reliability of ORRPS scheme is the best; ii) The AN technology can significantly improve the security of the system, although it has a little adverse affect on the reliability; iii) Infrequent light shadowing has the best reliability, frequent heavy shadowing has the worst outage performance, and the change of security is opposite; iv) The OP of SRS and ORRP schemes decreased with the increase of $K$ , while the IP changed on the contrary, and the reliability and security of TRRS scheme did not change obviously.

Outage Performance of Uplink NOMA in Land Mobile Satellite Communications

Non-orthogonal multiple access (NOMA) can be efficiently used in land mobile satellite (LMS) communications in order to increase link availability, coverage and reliability. In this letter, we study -for first time in the literature- the outage performance of an uplink LMS system consisting of two terrestrial user nodes which perform NOMA in the uplink, with either successive interference cancellation or joint decoding at the satellite receiver. Closed-form expressions for the outage probability are derived for both cases assuming composite shadowed-Rician fading channels. Finally, numerical results and simulations validate the theoretical analysis.

Double Differential Modulation for LEO-Based Land Mobile Satellite Communication

In this article, we propose a double differential (DD) modulation technique for low earth orbit (LEO)-based land mobile satellite (LMS) communication to overcome the carrier frequency offset, which is an inevitable effect with the LEO satellites. The symbol error rate (SER) expressions for the considered scheme over Shadowed–Rician fading channels with phase-shift keying (PSK) constellations are presented. Since a closed-form expression cannot be derived for quadrature PSK and higher order PSK constellations, an upper bound and a lower bound of SER are derived. The error performance of the DD modulated LMS system is compared to that of coherent modulation-based and single differential modulation-based LMS systems, and a significant performance gain of the proposed DD modulation-based system is observed. Furthermore, we have also studied the effects of elevation angle and LEO trajectory on the error performance of the considered system.

Physical-Layer Security in Space Information Networks: A Survey

Research and processing development on satellite communications has strongly re-emerged in recent years. Following the prosperity of various wireless services provided by satellite communications, the security issue has raised growing concerns since the space information network is susceptible to be eavesdropped by illegal adversaries in such a large-scale wireless network. Recently, the physical-layer security (PLS) has emerged as an alternative security paradigm that explores the randomness of the wireless channel to achieve confidentiality and authentication. The success story of the PLS technique now spans a decade and thrives to provide a layer of defense in satellite communications. With this position, a comprehensive survey of satellite communications is conducted in this article with an emphasis on PLS. We first briefly introduce essential background and the view of the satellite Internet of Things (IoT), as well as discuss related research challenges faced by the emerging integrated network architecture. Then, we revisit the most popular satellite channel model influenced by many factors and list the commonly used secrecy performance metrics. Also, we provide an exhaustive review of state-of-the-art research activity on PLS in satellite communications, which we categorize by different architectures including land mobile satellite communication networks, hybrid satellite-terrestrial relay networks, and satellite-terrestrial integrated networks. In addition, a number of open research problems are identified as possible future research directions.

An Integrated Circularly Polarized Transmitter Active Phased-Array Antenna for Emerging Ka-Band Satellite Mobile Terminals

This paper presents the design, development, and measurement results of a low-cost integrated circularly polarized (CP) active phased-array antenna (CP-APAA) technology with sidelobe level (SLL) control, operating at $Ka$ -band, for high throughput land-mobile satellite communication. The proposed CP-APAA is comprised of ( $4\times 16$ ) 64 elements in a rectangular grid array configuration. Eight commercial monolithic monolithic microwave/millimeter-wave integrated circuit. (MMICs) with eight-RF output channels have been used to control the phase and amplitude over the antenna aperture. For simplicity, the array antenna was designed in three metal layers and fabricated by a low-cost printed circuit board (PCB) technology as a proof-of-concept for a modular and scalable $Ka$ -band PAA with a wide steering angle. Measured radiation pattern shows a right-hand CP (RHCP) pattern with an axial-ratio (AR) level < 3 dB and low pointing error ≤1.5° over a scanning angular range of 0° to ±40°. Moreover, the amplitude excitation of the CP-APAA was tapered exponentially to control and reduce the SLL from 11 to 25 dB in boresight direction. Finally, toward a multibeam array implementation, two RHCP beams have been simultaneously generated at −30° and +20° scan angles.

A Non-Stationary 3-D Wideband GBSM for HAP-MIMO Communication Systems

The measurement results in land mobile satellite (LMS) communication scenario have shown that the propagation characteristic of LMS channel is a non-stationary process. In this paper, a non-stationary three-dimensional (3-D) wideband geometry-based stochastic model (GBSM) and the corresponding simulation model are proposed for high-altitude platform (HAP) multiple-input multiple-output (MIMO) communication system. The proposed GBSM uses two-dimensional (2-D) one-ring and 3-D multi-cylinders to model moving scatterers and near and far stationary scatterers, respectively. In the proposed GBSM, we assume that the multipath components (MPCs) scattering from the far stationary scatterers could appear again after their disappearance, and a two-state continuous-time Markov process is used to model the dynamic properties of MPCs such as MPCs appearance and disappearance, and the closed-form expressions of the survival probabilities of MPCs are derived. In the proposed GBSM, the long distance and small-scale time-variant parameters are also used to investigate the non-stationarities of HAP-MIMO channel. Using the survival probabilities of MPCs, the statistical properties of the proposed 3-D GBSM are derived. The numerical results demonstrate that the proposed 3-D GBSM is more practical to characterize the HAP-MIMO channel.

On the Performance of LMS Communication With Hardware Impairments and Interference

This paper investigates the performance of a dual-hop decode-and-forward (DF) relaying-aided land mobile satellite communication over Shadowed-Rician (SR) fading channels. A practical model for the satellite relaying system is first developed, where the impacts of satellite multi-beam antenna, radio propagation loss, and random shadowing are taken into account. Next, by assuming that the multi-beam satellite suffers from hardware impairments (HIs) and is perturbed by interference signals, we derive an equivalent end-to-end signal-to-interference-plus-noise-and-distortion-ratio of the system, and justify that the maximum ratio transmission at the source and the maximum ratio combining at the destination are the optimal transmit-receive beamforming schemes on the proposed HIs model. Then, closed-form expressions for the probability density function (PDF) of the sum of independent and identically distributed (i.i.d) squared SR random variables in the case of integer and rational Nakagami-m fading parameters are derived. Based on the derived PDF, new analytical expressions for the outage probability (OP) and average throughput are obtained in the presence of HIs and interference. Moreover, the asymptotic OP and average throughput at high signal-to-noise ratio are investigated to reveal the achievable diversity order of the system. Finally, Monte Carlo simulation results are provided to corroborate the analytical results.

Secrecy Performance of Land Mobile Satellite Systems With Imperfect Channel Estimation and Multiple Eavesdroppers

The inherent broadcast nature has exposed the land mobile satellite (LMS) communication systems to severe security threats in both the civil and military applications. This paper investigates the secrecy performance of a Shadowed-Rician fading multi-antenna LMS communication system with imperfect channel estimation, which consists of a satellite, a legitimate receiver and a cluster of unauthorized eavesdroppers who want to overhear the confidential message. Specifically, the analytical expressions for the probability of non-zero secrecy capacity are derived in terms of the Meijer-G functions, which provide an efficient means to evaluate the secrecy performance of the system. Then, both the exact and asymptotic secrecy outage probability expressions of the considered system are obtained. Furthermore, based on the simple asymptotic secrecy outage probability, we can reveal two key performance metrics, namely, the secrecy diversity order and secrecy array gain. Finally, simulation results are carried out to validate the theoretical results and show the superiority of employing multiple antennae in enhancing the secrecy performance for LMS communication systems. Our findings suggest that the secrecy diversity order only depends on the number of antennas at the legitimate receiver, and is independent of the imperfect channel estimation and the shadowing severities of both the main and eavesdropper channels.

Physical Layer Security for Land Mobile Satellite Communication Networks With User Cooperation

In this paper, we investigate the physical layer security of land mobile satellite (LMS) communication networks, where the multiple legitimate users and eavesdroppers are considered in the system. In order to obtain the best system performance, we propose the cooperating scheme for legitimate users to receive the main signal. Besides, we design two representative eavesdropping scenes for the eavesdroppers, namely, Scene I, colluding scene: the eavesdroppers cooperate with each other and wiretap the information of the main channel together, and the Scene II, non-colluding scene which is the best eavesdropping scene, namely, the most harmful eavesdropper will be selected to overhear the information channel. Furthermore, we obtain the closed-form expressions for the non-zero probability of secrecy capacity, the secrecy outage probability (SOP), and average secrecy capacity (ASC) based on the proposed user cooperation scheme in the presence of two eavesdropping scenes. In order to obtain more insights at the high signal-to-noise-ratios, the asymptotic expressions for the SOP and ASC are also derived under two scenes, from which we can derive the effect of different parameters on the system performance conveniently. Finally, some representative Monte Carlo simulation results are provided to verify the correctness of the obtained analytical results.

An iALM-ICA-Based Antijamming DS-CDMA Receiver for LMS Systems

We consider a land mobile satellite communication system using spread spectrum techniques where the uplink is exposed to multitone jamming attacks, and the downlink is corrupted by multipath fading channels. We propose an antijamming receiver, which exploits inherent low-dimensionality of the received signal model, by formulating a robust principal component analysis-based recovery problem. Simulation results verify that the proposed receiver outperforms the conventional receiver for a reasonable rank of the jamming signal.

Estimation of Rician K-Factor in the Presence of Nakagami-&lt;inline-formula&gt; &lt;tex-math notation="LaTeX"&gt;$m$ &lt;/tex-math&gt; &lt;/inline-formula&gt; Shadowing for the LoS Component

The received signal in Rician multipath channels is modeled as a complex constant, accounting for the main line-of-sight (LoS) path, added to a circular complex Gaussian random variable, modeling all the diffusive secondary paths. The Rician $K$ -factor is accordingly defined as the ratio between the powers of LoS and diffusive components. Under this (widely assumed) multipath model, a closed-form expression for the Rician $K$ -factor estimate is commonly obtained exploiting the second and fourth moments of the received signal amplitude. However, in mobile communications, random shadowing effects make the LoS component fluctuating (Rician shadowed model) leading to a performance degradation of the conventional estimator. With focus on land mobile satellite communications, in this letter, a novel estimation procedure of the Rician $K$ -factor, aimed at avoiding the bias error of the conventional estimator when the LoS component is Nakagami- ${m}$ distributed, is proposed and assessed. Specifically, the estimate is computed using the solution of a system of three equations and three unknowns in conjunction with the likelihood function of the received signal. The performance analysis shows that the new estimator can guarantee better performance than the conventional estimator.

OSTBC Transmission in Shadowed-Rician Land Mobile Satellite Links

In this paper, we study the transmission of orthogonal space–time block codes (OSTBCs) over a shadowed Rician (SR) land mobile satellite (LMS) link. Specifically, we derive the symbol error rate (SER), diversity order, and the average capacity of the OSTBC-transmission-based scheme over the SR fading LMS communication systems. First, we consider the independent and identically distributed (i.i.d.) SR fading channels and derive the expressions of moment-generating function (mgf) in terms of the Meijer-G function. By substituting the Meijer-G function in terms of hypergeometric function and then by considering the asymptotic approximation of hypergeometric function, the analytical diversity order of the scheme is obtained. The ergodic capacity of the scheme is derived by using the mgf-based approach. The effect of elevation angles over the SER performance of the scheme is analyzed, and it is observed that the performance of the system is improved with increasing values of elevation angles. Next, we consider the OSTBC transmission over correlated SR fading channels and derive the expressions of mgf, SER, diversity order, and average capacity of the considered setup. In particular, it is demonstrated in this paper that, by employing an additional transmit antenna at the satellite along with Alamouti code, the error rate of the LMS communication system can be significantly improved. It is also shown that the correlation has no impact on the diversity order of the system, but it adversely affects the capacity of the system.

Predictive relay-selection cooperative diversity in land mobile satellite systems

Cooperative diversity protocols promise a new dimension of diversity that provides better communication by engaging nearby relays in forming a ‘virtual’ array of antennas for combined signal transmission. The current incremental cooperative diversity algorithms incrementally select best relay(s) to cooperate based on the channel quality reported by the relays. However, the algorithms do not take into consideration the fact that the chosen best relay(s) at estimation may not always be the best at the time of communication. This is due to the time delay between the relay selection and its transmission of signal (problem of outdated channel quality information (CQI)). To solve this problem, the concept of channel prediction is introduced and employed whereby each relay determines a predicted value of its CQI based on its past measurements. The paper therefore develops a novel predictive relay-selection (PRS) cooperative diversity model that seeks to improve land mobile satellite communication through prediction protocols. In the model, the chosen best relay is the one with the best predicted CQI value instead of the traditional outdated one. Performance analysis of outage probability and average bit error probability for the newly developed PRS cooperation shows that the PRS cooperation is better than direct and outdated CQI relay communication. Copyright © 2015 John Wiley & Sons, Ltd.

Adaptive Long-Range Prediction of Three-State LMS Channel Model

In order to provide the accurate real-time knowledge of future channel state information for the adaptive transmission of narrowband land mobile satellite (LMS) communication systems, an adaptive long-range prediction (ALRP) method, suitable for a three-state LMS channel model at S-band, is proposed. The very slow shadowing conditions' variations of satellite propagation channel can be described as a three-state Gilbert---Elliot channel model based on Markov chain. The channel state of future long-range is predicted based on weighting prediction while the parameters of linear auto-regression model are updated using an iterative adaptive tracking algorithm. The future channel fading series are predicted by the latest observations within current channel state. Simulation results show that the proposed method can be used to predict the future long-range channel state and fading series of three-state Gilbert---Elliot channel model accurately; and it is observed from the mean square error results that the prediction performance of the ALRP method is much more accurate than that of long-range prediction method. Moreover, the method has advantage of real-time and low-complexity which will make the adaptive transmission techniques feasible for LMS channel models.

육상 이동 위성 시스템의 통신 성능 향상을 위한 MIMO 원형 편파 급전 네트워크

본 논문은 육상 이동 위성(Land Mobile Satellite: LMS) 시스템의 통신 성능 향상을 위해 기존의 <TEX>$2{\times}2$</TEX> MIMO 채널에서 <TEX>$4{\times}4$</TEX> 채널로 확장할 수 있는 MIMO 원형 편파 급전 네트워크를 제안한다. 기존의 추가적인 통신 채널 확보를 위해서는 위성국에서 안테나 설치 공간상의 제약이 있기 때문에 이격 거리가 충분한 추가 위성국을 필요로 한다. 이로 인한 비용 및 MIMO 통신 채널의 한계 문제를 극복하기 위하여, 동일한 원형 편파 간에 이격 거리가 없이도 높은 격리성을 확보할 수 있는 MIMO 원형 편파 급전 네트워크를 제안하였다. 제안하는 급전 네트워크의 포트간 격리성과 각 포트의 매칭 상태를 수식적으로 증명하였고, <TEX>$4{\times}4$</TEX> MIMO 채널의 통신 성능 향상을 채널 모델 측면에서 제시 및 확인하였다. MIMO 원형 편파 급전 네트워크를 원형 편파 패치 안테나 구조로 실제 제작하고 측정하여 7~10 dB의 다이버시티 이득을 얻었고, 약 1.8배로 채널 용량이 향상되었음을 확인하였다. In this paper, we propose the MIMO circular polarization feed network to enhance the communication performances from the previous <TEX>$2{\times}2$</TEX> MIMO channel to <TEX>$4{\times}4$</TEX> channel for Land Mobile Satellite communication system. The only possibility to extend the communication channel is to use the additional satellite because of the limitation of satellite spaces to install additional antennas. For overcoming this problems, we propose the MIMO circular polarization feed network to secure the isolation characteristics without the distant antenna space. The port isolation characteristics and each port impedance matching conditions are numerically verified and we suggest the <TEX>$4{\times}4$</TEX> MIMO channel model of the proposed system and the performances are verified. The fabricated circular polarization patch antennas with the proposed feed network are measured in the reverberation chamber and 7~10 dB of diversity gain and 80 % increasement of channel capacity are obtained.