Mobile Satellite Communication Systems Research Articles

MOBILE SATELLITE COMMUNICATION SYSTEM WITH PASSIVE TERMINALS BASED ON MODULATING RETRO-REFLECTORS

In this work, a qualitative and quantitative comparison of satellite mobile communications systems with various altitudes of the orbits of spacecraft was carried out. A study of the conditions for the spacecraft to be located in the visibility range of the ground terminal and an analysis of the time spent by the satellite in the visibility zone depending on the height of the orbit was made. According to the results of this analysis and taking into account the fact that the low orbit area around the Earth is very densely filled with artificial satellites and space debris, it can be concluded that it is advisable to increase the radius of the orbit of telecommunication satellites. At the same time the geostationary orbit, which has obvious advantages in terms of coverage, is also quite densely filled with spacecraft, and is very high for the efficient operation of low-power mobile ground terminals. Taking into account these features, it is concluded that the use of medium-height orbits for telecommunication satellite systems is promising for which global coverage of the Earth’s surface can be achieved using several dozen satellites. In addition, the distance to the Earth’s surface will be small enough to provide a high signal-to-noise ratio and, as a result, the system will provide a high bitrate. A computer simulation of the operation of a satellite telecommunication system was carried out for a different number of spacecraft and various parameters of their orbits in order to determine the conditions for achieving global coverage. This simulation confirms the conclusions regarding the feasibility of using medium orbits. The concept of using passive terminals based on modulating retroreflectors was proposed. It means the reflection of a satellite signal by a ground terminal without emitting its own electromagnetic energy. The energy of the terminals is spent only on the modulation of the reflected signal. This approach will significantly reduce the energy consumption of ground terminals and thereby increase mobility. It is proposed to carry out phase and polarization modulation of the signal using liquid crystals or metamaterials.

Performance analysis for multi-user integrated satellite and UAV cooperative networks

Satellite and unmanned aerial vehicle (UAV) communications are the two most promising technologies for providing seamless connectivity to mobile users. In this paper, we investigate the performance of a multi-antenna multi-user integrated satellite and UAV cooperative network (ISUCN). Specifically, by taking many practical parameters, such as antenna pattern and path loss into account, we first obtain the maximal output signal-to-noise ratio (SNR) expression for the ISUCN, where multi-antenna UAV is employed as an aerial relay with threshold-based amplify-and-forward (AF) protocol to assist signal transmission between satellite and multiple ground users. Then, based on the commonly used assumption that the satellite link undergoes Shadowed-Rician fading while the terrestrial links experience Nakagami-m fading, we derive an analytical expression for the outage probability (OP) of the considered network. Furthermore, the asymptotical OP expression in high SNR regime is developed to evaluate the achievable coding gain and diversity order conveniently. Finally, numerical results are given to confirm the validity of the theoretical formulas and reveal the effects of representative parameters on the system performance. Our works provide useful guidelines for the engineers in the designing ISUCNs for futuristic satellite mobile communication systems.

Feasibility of LTE-Based GEO Satellite Mobile Communication Systems to Support VoIP for Handheld Terminals

To facilitate the integration of terrestrial and satellite mobile communication systems in the future, the new generation of satellite mobile communication system should be Long-term evolution (LTE)-based. In LTE, voice is carried by Internet protocol (IP) packets (voice over IP, VoIP). The feasibility of LTE-based Geosynchronous earth orbit (GEO) satellite mobile communication systems for VoIP is discussed. Detailed link budgets are created for typical handheld terminals. The effectiveness of Physical resource block (PRB) bundling and Transmission time interval (TTI) bundling for the capacity improvement of downlink and uplink are evaluated, and further uplink improvement for low level terminals by Narrowband resource block (NRB) scheme is also studied. The analysis results show that the downlink VoIP transmission is mainly power limited, and optimization of PRB or TTI bundling can maximize the capacity. For uplink, only highlevel terminals can support VoIP under the normal LTE frame structure, and TTI bundling and Resource block (RB) block techniques can help the low-level terminals support VoIP transmission.

Simulation Model of Transport Traceability System for Transit Customs Goods within the EEU

Abstract This article reviews the transport traceability system for customs goods within the Eurasian Economic Union, which is the automated data system used to control integrity and movement of cargo section of a carrier vehicle by means of satellite navigation system, mobile cellular communication system and satellite communication system. Article is dedicated to the development of a model that simulates functions of transport traceability system for customs goods, which are being transported using the international transit transport corridors, and this model would be also used for assessment of a demand on electronic seals by seal installation stations, and for determination of correspondence between simulated transport route and actual travel time. Simulation model was already used in a test project, where it was integrated into “EVAC Transit” transport traceability system, and it has proven it’s operability and efficiency.

Deep Learning Network for Multiuser Detection in Satellite Mobile Communication System.

A multiuser detection (MUD) algorithm based on deep learning network is proposed for the satellite mobile communication system. Due to relative motion between the satellite and users, multiple access interference (MUI) introduced by multipath fading channel reduces system performance. The proposed MUD algorithm based on deep learning network firstly establishes the CINR optimal loss function according to the multiuser access mode and then obtains the best multiuser detection weight through the steepest gradient iteration. Multilayer nonlinear learning obtains interference cancellation sharing weights to achieve maximum signal-to-noise ratio through gradient iteration, which is superior than the traditional serial interference cancellation algorithm and parallel interference cancellation algorithm. Then, the weights with multiuser detection through multilayer network forward learning iteration are obtained with traditional multiuser detecting quality characteristics. The proposed multiuser access detection based on deep learning network algorithm improves the MUD accuracy and reduces the number of traditional multiusers. The performance of the satellite multifading uplink system shows that the proposed deep learning network can provide high precision and better iteration times.

USTLD mapper design for APSK constellations over satellite links

AbstractSpace‐time block code (STBC)–based multiple‐input–multiple‐output techniques have been considered recently to enhance the performance of mobile satellite communication systems in terms of link reliability. Uncoded space‐time labelling diversity (USTLD) is a diversity technique that is a direct extension of the STBC system and further improves its performance. A USTLD system is proposed in this paper that is designed specifically for satellite to mobile station links. The circular M‐ary Amplitude Phase‐Shift Keying (MAPSK) constellation, which is adopted by the most recent satellite broadcasting standard Digital Video Broadcasting standard for nonlinear satellite links (DVB‐S2X), is applied to the USTLD system. The most critical aspect of developing a USTLD system is the design of the secondary mapper to achieve labelling diversity. Existing square M‐ary Quadrature Amplitude Modulation (MQAM) approaches to USTLD mapper design are adapted for appropriate 16APSK and 64APSK constellations from the DVB‐S2X standard. Various metrics are derived to quantitatively compare mapper designs for a Nakagami‐q fading channel. Theoretical results, verified by Monte Carlo simulations, show that the best of the MAPSK USTLD mappers considered achieve a gain of approximately 4 dB for 16APSK and 5 dB for 64APSK when compared to the Alamouti STBC system. Furthermore, a study is conducted to analytically compare USTLD mappers using the derived metrics for both MQAM and MAPSK. It is concluded that a two‐stage approach is the most accurate methodology for comparing USTLD mapper designs.

The development of maritime satellite communications since 1976

This research note runs on from the note published by the author in this issue of IJMH. It describes the development of Maritime Satellite Communications (MSC) systems for all type of commercial and military seagoing and inland sailing vessels since the 1970s. The main functions of MSC systems are to enhance the safety and security of seagoing vessels, mainly by alerting and Search and Rescue (SAR) operations, and to improve communication facilities between ships and shore infrastructures. The first MSC Geostationary Earth Orbit (GEO) system for military applications was developed in 1976 by the US and other partners, which soon became available for merchant ships. The next step was the development of an independent and international MSC system. To overcome the disadvantages associated with HF/VHF radio propagation and frequency congestions, the International Maritime Organization (IMO) in 1979 encouraged all member nations to establish Maritime Mobile Satellite Communication (MMSC) systems. At the behest of IMO and United Nations (UN) Maritime Body, and pursuant to the Convention on the International Maritime Satellite Organization, signed by 28 countries in 1976, the International Maritime Satellite (INMARSAT) Organization was founded.

Software Testing Method Based Mobile Communication Equipment of Maritime Satellite

Focusing on the different performance of communication links between satellite and mobile terminals, this paper creates an adaptive channel model for satellite mobile communication, which can accurately reflect the multipath, shadowing and other problems in signal propagation and effectively forecast and evaluate the modulation, demodulation, coding and constellation distribution of satellite mobile communication systems. Then, the author put forward a software testing method for mobile communication equipment of maritime satellite. The proposed method achieves comprehensive verification and evaluation from the aspects of equipment applicability, reliability, durability, etc. The research findings provide a software test approach and the evaluation basis for improving the performance of communication equipment.

Near Optimal Timing and Frequency Offset Estimation for 5G Integrated LEO Satellite Communication System

The integration of satellite and terrestrial 5G networks aims to provide ubiquitous coverage, improve service reliability, and enable the network scalability. However, the inherent characteristics of satellite channels bring challenges on the air interface design of integrated terrestrial-satellite networks. For example, for low earth orbits (LEO) mobile satellite communication (SatCom) system, it is unclear so far whether the 5G new radio (5G-NR) synchronization signals could meet the requirement of timing and frequency offset estimation in the presence of large Doppler shifts. In this paper, we investigate time and frequency synchronization for the downlink transmission of 5G-NR signals over LEO satellite channels. Starting from the maximum log-likelihood criterion for timing offset estimation given the observation of the received primary synchronization signals (PSS), we derive an upper bound of the objective function for simplicity. With a priori information that the maximum Doppler shift of LEO satellite-ground link is within a specific range, we construct the local synchronization sequence via using the modulated discrete prolate spheroidal sequences (DPSS) vectors. Then the timing offset estimation can be recast into a one-dimensional peak search problem. Moreover, the cyclic prefix (CP) structure of orthogonal frequency division multiplexing (OFDM) can be utilized to improve the estimation performance further. Once the timing and frequency offset are captured in the above initial synchronization phase, the tracking synchronization can be much simplified as the variation of both the timing and frequency offset is very small between two adjacent synchronization blocks. Simulation results show that by using the proposed algorithms, the 5G-NR signals can achieve near optimal downlink time and frequency synchronization in typical LEO SatCom systems.

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.

Динамический выбор радиолиний для систем подвижной спутниковой связи

In this paper presents suggestions for the noise immunity improval of mobile satellite communications lines in difficult physical and geographical conditions through the use of automatic dynamic identification algorithms for the suitability of radio lines and the dynamic antenna orientation devices of mobile satellite communications systems. Based on the results obtained, recommendations for practical application are formulated.

A Low-Cost <italic>Ka</italic>-Band Circularly Polarized Passive Phased-Array Antenna for Mobile Satellite Applications

This paper presents a low-profile, high-performance, and low-cost Ka -band circularly polarized (CP) passive phased-array antenna (PAA) system. A $1\times 4$ passive subarray operating at the Ka -band frequency band is investigated, developed, and tested as a possible building block for mobile satellite communication systems. In particular, a CP antenna integrated with a high-performance passive phase shifter is presented and experimentally verified. A new low-cost and low-profile magnetic actuator is proposed to precisely control the phase state of the phase shifter. A 3-D printed polymer package is utilized to enclose the phase shifter and reduce the environmental effects. The proposed CP passive PAA achieves high-performance right-hand CP radiation with high cross-polarization discrimination over a wide scan angle from 0° to ±38° over the frequency band (29.5–30.5 GHz). An axial ratio (AR) < 3 dB is demonstrated over the entire scanning range. Moreover, the measured radiation efficiency is 60% at boresight. The gain drops by 1 dB at ±38° scanning angles.

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.

AMP dual-turbo iterative detection and decoding for LDPC coded multibeam MSC uplink

The uplink of mobile satellite communication (MSC) system with hundreds of spot beams is essentially a multiple-input multiple-output (MIMO) channel. Dual-turbo iterative detection and decoding as a kind of MIMO receiver, which exchanges soft extrinsic information between a soft-in soft-out (SISO) detector and an SISO decoder in an iterative fashion, is an efficient method to reduce the uplink inter-beam-interference (IBI), and so the receiving bit error rate (BER). We propose to replace the linear SISO detector of traditional dual-turbo iterative detection and decoding with the AMP detector for the low-density parity-check (LDPC) coded multibeam MSC uplink. This improvement can reduce the computational complexity and achieve much lower BER.

Distributed RZF Precoding for Multiple-Beam MSC Downlink

Regularized zero-forcing (RZF) precoding can be used in multiple-beam mobile satellite communication (MSC) system downlink to combat interbeam-interference for high energy efficiency. We adopt the interference cancelation idea in approximate message passing (AMP) algorithm and propose an interference cancelation message passing (IC-MP) algorithm. To combine the virtues of both IC-MP and AMP, a hybrid message passing (H-MP) algorithm is also proposed. Simulation results show that H-MP has the best performance compared with IC-MP and AMP, and may even outperform the centralized RZF precoding.

An enhanced authentication with key agreement scheme for satellite communication systems

SummaryTo ensure secure communication in satellite communication systems, recently, Zhang et al presented an authentication with key agreement scheme and claimed that their scheme satisfies various security requirements. However, this paper demonstrates that Zhang et al's scheme is insecure against the stolen‐verifier attack and the denial of service attack. Furthermore, to authenticate a user, Zhang et al's scheme requires large computational load to exhaustively retrieve the user's identity and password from the account database according to a temporary identity and then update the temporary identity in the database. To overcome the weaknesses existing in Zhang et al's scheme, we proposed an enhanced authentication with key agreement scheme for satellite communication systems. The analyses of our proposed scheme show that the proposed scheme possesses perfect security properties and eliminates the weaknesses of Zhang et al's scheme well. Therefore, from the authors' viewpoints, the proposed scheme is more suitable for the authentication scheme of mobile satellite communication systems.

A traffic-awareness dynamic resource allocation scheme based on multi-objective optimization in multi-beam mobile satellite communication systems

Mobile satellite communication systems play an important role in space information networks. They mostly operate at the L or S band and have multiple beams efficiently reusing the limited spectrum. Advanced technologies, such as beamforming, are used to generate numerous beams through multiple feeders, and each beam’s power allocation is correlated and constrained. Frequency reuse among multiple beams results in co-channel interference issue, which makes bandwidth allocation among multiple beams coupled. It is a challenging topic to optimize the resource allocation in the real-time service traffic. In this article, a new multi-objective programming scheme is used to solve the dynamic resource allocation problem, guaranteeing high quality-of-service for multiple services of different priorities. Since the dynamic resource allocation problem is formulated as NP-hard, a new traffic-aware dynamic resource allocation (TADRA) algorithm is proposed. This algorithm is proved to be optimal in terms of the Pareto-front under constraints of co-channel interference and onboard transmit power. Simulation results show that the trade-off is well balanced between the call completion ratio in high priority and the throughput for video and data services in medium and low priorities. Additionally, it is shown that the new multi-objective programming scheme, based on the traffic-awareness dynamic resource allocation algorithm, can rapidly achieve the Pareto-front solutions and reduce the computing complexity to a large extent.

RWG‐integrated SIW splitter for large scale SATCOM phased array applications

AbstractIn this article, the hybrid transition power splitter, which consists of metallic rectangular waveguide and substrate integrated waveguide, is presented for large‐scale millimeter‐wave antenna array broad band mobile satellite communication system. The power is coupled between the RWG and the SIW through two center‐slot transition, one etched on the SIW ground plane and the other cut through metallic RWG narrow side wall. The two‐way RWG‐SIW transition splitter was designed and simulated; then the four‐way splitter was designed, fabricated, and tested. The measured results show good agreements with the simulated ones and the measured return and insertion loss better than 10 and ∼1.50 dB were experimentally achieved over the band 28.70–30.20 GHz, respectively.

Non-orthogonal multi-carrier transmission for internet via satellite

As the important complementary to terrestrial mobile communications, Internet via satellite can extend the coverage of communication and improve the continuity of data services. To build a space-terrestrial integrated communication system is the inevitable trend in the future. Taking into account combination of 5th generation (5G) terrestrial mobile communication system and satellite communication system, it is necessary to evaluate the promising 5G air interface waveform which can be adopted by satellite. In this paper, several non-orthogonal multi-carrier transmission schemes are evaluated and generalized frequency division multiplexing (GFDM) is advised as potential scheme of space-terrestrial integrated communication system. After the overview of GFDM, the implementation of GFDM transceiver is discussed respectively in time-domain and in frequency-domain. By deriving and comparing implementation complexity, GFDM modulation in time-domain is more suitable for satellite communication system. Then the properties of demodulation algorithms are specified. Based on designed pilot subcarriers, a new improved receiving algorithm is proposed in the end of the paper. The improved algorithm solves the problem of inter subcarriers interference (ICI) in matched filtering (MF) receiver and improves the receiving symbol error rate (SER) obviously. The simulation and analysis prove that the proposed algorithm is effective.

Satellite speech quality measurement model based on a combination of auditory envelope feature and link loss

This paper focuses on Speech Quality Measurement for a satellite mobile communication system. In contrast to ground mobile communication systems, satellite speech quality measurement suffers from obvious jitter of long delays and severe satellite link losses. Auditory feature sensation and link loss measurement are most popular speech quality measurement models. However, long delay would cause the auditory feature sensation model with spreading of power spectrum, which furtherly diffuses the auditory spectrums to prevent human from hear correct responses. Nevertheless, measured error of link loss measurement would be enlarged gradually during the process of voice services. Therefore, a new speech quality measurement model based on the combination of auditory feature extraction from voice signal envelope and link loss from channel distortion is proposed. We analyze signal temporal envelope features and make power spectrum into auditory feature spectrum. The jitter of long delay and link loss are modeled as parameters to modify and compensate for the auditory feature spectrum, which also reduce the measurement distortion from transmission Doppler frequency offset to voice tone in satellite channel. A more understandable sensation estimation scores is proposed to present speech quality scores. The experimental results reveal that the new model reduces evaluation RMSE by 9.8% and is suited to the satellite mobile communications environment.