Iterative decoding of rate adaptive multilevel coded modulation for mobile satellite communication

Adaptive Demodulation (ADM) is a newly proposed rate-adaptive system which operates without requiring Channel State Information (CSI) at the transmitter (unlike adaptive modulation) by using adaptive decision region boundaries at the receiver and encoding the data with a rateless code. This paper addresses the design and performance of an ADM scheme for two common differentially coherent schemes: M-DPSK (M-ary Differential Phase Shift Keying) and M-DAPSK (M-ary Differential Amplitude and Phase Shift Keying) operating over AWGN and Rayleigh fading channels. The optimal method for determining the most reliable bits for a given differential detection scheme is presented. In addition, simple (near-optimal) implementations are provided for recovering the most reliable bits from a received pair of differentially encoded symbols for systems using 16-DPSK and 16- DAPSK. The new receivers offer the advantages of a rate-adaptive system, without requiring CSI at the transmitter and a coherent phase reference at the receiver. Bit error analysis for the ADM system in both cases is presented along with numerical results of the spectral efficiency for the rate-adaptive systems operating over a Rayleigh fading channel.

Communication satellites have a much longer propagation delay than terrestrial communication networks such as cellular or WiFi. In addition, as the carrier frequency moves up, mobile satellite communications show worse performances than the conventional fixed satellite communications. The mobile satellite service (MSS) has not been actively pursued with long latency at high-frequency bands for future applications. In this paper, the adverse impact of long propagation delay in the conventional satellite system is investigated with various user mobility and Doppler-shifted carrier frequency. The satellite network is modeled as a basic delayed feedback channel system and the communication performance is analyzed under delayed channel state information (CSI) for assessing the system feasibility in mobile conditions. The results of performance analysis are provided at high-frequency bands with high-speed user movement, specifically on the outage probability and the channel capacity exploiting three types of channel models: conventional land mobile satellite (LMS) channel models of E. Lutz and C. Loo, and Nakagami fading model. In the circumstance with various user speeds, system performances are evaluated with different propagation delays in the LMS channel models and for line-of-sight (LOS) components in the Nakagami fading. In addition, the conventional models are compared depending on different altitudes for geostationary orbit (GEO), medium earth orbit (MEO), and low earth orbit (LEO) satellites, as well as high-altitude platforms (HAP).

Experiments on mobile satellite communications are being carried out to determine if they are technically feasible for future domestic satellite services in the Experimental Mobile Satellite System project, which uses Engineering Test Satellite-V. Experimental ISDN (integrated services digital network) basic-rate communications services have also been offered for marine vehicles. The authors describe the configuration of an experimental system for maritime ISDN satellite communications, and the characteristics of ISDN basic-rate interface connections for the digital telephones, G4 facsimiles, and color video-phone terminals of terrestrial ISDN services. This experiment provided much information for designing future mobile satellite communications systems. Moreover, it indicates that forward error correction in a mobile satellite link with poor transmission quality is very effective at improving the communication quality of mobile satellite systems. >

From the moment the air/aero/aerial objects appeared the necessity of monitoring for them arose and were solved using different tools, such as radio communications, radio direction finding, radar and others. With the advent of global satellite navigation, the massive introduction of navigation equipment began in almost all areas of human activity and especially in mobile (moving) objects (cars, aircraft, ships, etc.). This allowed aircraft crews to accurately determine their coordinates in real time under any weather conditions. However, the organization of uninterrupted data transmission to ground control centers remained problematic. In this regard, aircraft monitoring systems were primarily installed on military and civil aircraft, while the other categories and types of aircraft were equipped only with communication systems. Thus, currently, there is the lack of navigation devices allowing flight monitoring and communication in small aviation. As a result, in case of emergency landing of small aircraft, it takes a lot of time and effort to find its location, therefore providing emergency assistance to passengers and crew is not possible. This problem can be solved by the system for determining the location of small aircraft using technologies of global navigation satellite systems and mobile satellite communications. This system includes devices for registering the location of the observed object, transmitting data via mobile cellular and satellite communications, processing, storage and displaying of data. The proposed system, by continuously recording and transmitting aircraft location data to the ground control center, helps minimize time and narrow the search area of the aircraft that made an emergency landing.

This paper gives an overview over the essential physical phenomena of the satellite communications channel, with particular emphasis on the land mobile satellite (LMS) channel. Then it describes measurement and modelling techniques for the LMS channel and gives an overview over this field. The characteristics of the LMS channel are discussed, and “historic” DLR channel measurements are reviewed. From this, a narrowband channel model is derived, and parameters of the channel model, resulting from measurements, are presented. Finally, the paper reviews a wideband LMS model based on a tapped delay line.

A multi-beam mobile satellite communications system is proposed. This system has been investigated for maritime and land mobile satellite communications services. The dominant characteristics of the system are as follows: 1 S-band (2.6/2.5GHz) is adopted, which is the most favorable frequency band under 10GHz judging from propagation characteristics. 2 An optimized weight budget design method of satellite is proposed, maximizing channel capacity of system. 3 A new transponder configuration method is adopted, which is tolerant of traffic variation.

This paper reviews the demand for mobile satellite communications and radiodetermination services from the maritime, aviation, and land mobile communities. It briefly examines existing alternatives and the factors that are affecting the growth and development of mobile satellite communications, with particular reference to INMARSAT. Future mobile earth station standards and services are described as are the key technological developments and challenges, which need to be met before mobile satellite services-on aircraft, the smallest of vessels, and land vehicles-become widely available at significantly lower costs than today. The authors are cautiously optimistic that the 1990's will see a rapid growth of mobile satellite services, but such growth will depend in large part on the resolution of certain institutional and technical problems, particularly relating to the limited mobile satellite spectrum available at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</tex> -band.

New approach to simulation of continuous and discrete land mobile satellite communication channel (LMSC) is considered. The main topic addresses modeling of the fading and shadowing of the received signal as correlated non-Gaussian Markov processes, generated by corresponding nonlinear stochastic differential equations (SDE). Simulation of the continuous LMSC conceptually coincides with the two-state propagation model, known as the most effective in the scenario considered. The new model has a very good fit with all previous results, both modeled and stored from the real channel. It also resolves almost all disadvantages of the previous approaches: limitations in random process generation and discontinuity of the fading process at the state transfers.

An analytical derivation of the probability of bit error noncoherent frequency-shift keying (FSK) and coherent phase-shift keying (PSK) signals transmitted through a land-mobile satellite channel is described. The channel characteristics used in the analysis are based on a recently developed model which includes the combined effects of fading and shadowing. Analytical expressions for the probability of bit error of FSK and coherent phase-shift keying (CPSK) signals are obtained. The results show that large amounts of signal-to-noise ratio (SNR) are required to compensate for the combined effect of fading and shadowing. An analytical expression for the irreducible probability of bit error of a CPSK signal due to phase variations caused by fading and shadowing is derived. The results described should be useful in the design of land mobile satellite communication systems.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

In high‐speed digital transmission in mobile satellite and land mobile communications, one of the serious problems is the effect of waveform distortion due to the frequency‐selective fading. This paper considers the GMSK modulation system, which is considered as useful as the modulation scheme for digital mobile communication.The effect of the waveform distortion produced by the time‐delay spread of the scattered interfering waves in the Nakagami‐Rice fading channel is considered and the bit error rate is calculated theoretically. Numerical examples of bit error rate performance are illustrated. It is shown that the bit error rate is improved when there is an average delay time or a time‐delay spread in the scattered interfering wave, compared with the case without a delay. However, the effect is relatively small.

Improved non-coherent receivers for mobile and personal satellite communications are presented and evaluated. The channel is assumed as being corrupted by shadowing and multipath fading. The results demonstrate that the receivers are capable of reducing the error floors considerably and provide improvements higher than 12 dB. The technology is promising and a good candidate for use in the development of future wireless multimedia personal communication terminals.

Mobile satellite communication is becoming a crucial component for broadcast and broadband coverage in professional, commercial, military and emergency scenarios. Mobile devices and network control center (NCC) are the basic components of Low-Earth-Orbit (LEO) satellites which communicate with each other with the help of gateways. The communication between these components needs high security. The various existing protocols for the environment of mobile satellite communication are insecure against numerous attacks and can be easily attacked by an adversary. So, there is an indispensable requirement of a reliable protocol which can offer efficient and secure communication for mobile satellite system. Therefore, a robust key agreement authentication scheme for mobile satellite environment is proposed in this article. The proposed protocol is developed according to the major security demands in the satellite communication networks. Our protocol provides mutual-authentication, session-key agreement and correct notion of user anonymity. The performance analysis for evaluation shows that the storage, communication and computation cost of the proposed protocol is less than many of existing protocols. Moreover, our protocol offers additional security features than that are available in the existing protocols. Hence, our protocol offers a secure authentication and key agreement for mobile satellite systems.

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.

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.

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.