Pantelis-Daniel M. Arapoglou

Satellite communications at KU, KA, and V bands: Propagation impairments and mitigation techniques

This article surveys the alternative fade mitigation techniques for satellite communication systems operating at Ku, Ka and V frequency bands. The specific phenomena influencing the propagation of radiowaves on Earth-space links are also overviewed. Emphasis is placed on modeling, experimental work carried out in the past, and practical implementations related to each mitigation technique.

MIMO over Satellite: A Review

The present article carries out a review of MIMO-based techniques that have been recently proposed for satellite communications. Due to the plethora of MIMO interpretations in terrestrial systems and the particularities of satellite communications, this review is built on two pillars, namely fixed satellite and mobile satellite. Special attention is given to the characteristics of the satellite channel, which will ultimately determine the viability of MIMO over satellite. Finally, some future research directions are identified.

Long-term rain attenuation probability and site diversity gain prediction formulas

Simple models for long-term induced rain attenuation on a slant path and site diversity gain are presented in this work. As verified by numerous tests against the ITU-R databank and other data from the literature, the proposed models exhibit a very good performance. The novel slant path rain attenuation prediction model compared to the ITU-R one exhibits a similar behavior at low time percentages and a better root-mean-square error performance for probability levels above 0.02%. Moreover, comparing the proposed site diversity gain model with other widely accepted models from the literature, an improved performance is observed for distances less than 15 km, while the model performs equally well for greater distances. Furthermore, a sensitivity test between the proposed and Hodges formula with respect to the separation distance D is also carried out. While the lower limit of the proposed model is found to be D=1.7 km, its extension covering large-scale site diversity is successfully compared with experimental data coming from Japan. The set of presented models exhibits the advantage of easy implementation with little complexity and is considered useful for educational and back of the envelope computations.

To MIMO or Not To MIMO in Mobile Satellite Broadcasting Systems

This letter studies the potential capacity advantages of introducing a dual polarization per beam paradigm instead of the conventional single polarization per beam in mobile satellite broadcasting systems. This enables the application of MIMO techniques, not yet thoroughly investigated for mobile satellite systems. We engage in a fair system performance comparison between single polarization SISO and dual polarization non-MIMO and MIMO configurations based on the DVB-SH state-of-the-art mobile satellite standard. Along the course, the major advantages and pitfalls of a dual polarization per beam system from an interference, antenna, payload, and capacity perspective are highlighted.

The Land Mobile Earth-Space Channel

Research on mobile satellite and high-altitude platform (HAP) systems (MSHSs) has recently proliferated because of the allocation of additional spectrum, the intense standardization efforts from different international institutes, the detailed studies pursued by the European [European Space Agency (ESA)], French (CNES), and Japanese (JAXA) space agencies, and the commercial impact of some of the corresponding system implementations. A survey of mobile satellite systems is provided. Enhanced land mobile Earth-space (LMES) channels encompassing a variety of geometries, frequency bands, and propagation environments are critical for developing and assessing the performance of these new MSHS paradigms. In this article, we provide a survey of the state-of-the-art measurement campaigns, modeling approaches, and generative methods concerning the LMES channel and pinpoint future research directions. We refer to LMES since, due to the close similarities they exhibit, we present channels from both geostationary (GEO) satellites and quasi-stationary HAPs. Most of the cited models apply in both cases. General emphasis is on statistical/physical narrow-band models, which is the norm in LMES channels.

Intercell Radio Interference Studies in Broadband Wireless Access Networks

Capacity has become of primary importance in broadband wireless access (BWA) networks due to the ever-increasing demand for multimedia services and the possibility of providing wireless Internet, leading to their standardization by IEEE (802.16 WirelessMAN) and ETSI (BRAN HIPERACCESS). The major factor limiting capacity in such systems is interference originating from adjacent cells, namely intercell interference. This paper presents a general analysis of intercell interference for a spectrally efficient BWA cellular configuration. It examines the statistical properties of the carrier-to-interference ratio in both downstream and upstream channels. The focus is on the spatial inhomogeneity of rain attenuation over multiple paths, which is the dominant fading mechanism in the frequency range above 20 GHz, especially when two-layered [i.e., line-of-sight (LOS) and non-LOS] architectures are involved. Besides attenuation from precipitation, various architectural and propagation aspects of local multipoint distribution service systems are investigated through simulations, and worst-case interference scenarios are identified

Gateway Switching in Q/V Band Satellite Feeder Links

A main challenge towards realizing the next generation Terabit/s broadband satellite communications (SatCom) is the limited spectrum available in the Ka band. An attractive solution is to move the feeder link to the higher Q/V band, where more spectrum is available. When utilizing the Q/V band, due to heavy rain attenuation, gateway diversity is considered a necessity to ensure the required feeder link availability. Although receive site diversity has been studied in the past for SatCom, there is much less maturity in terms of transmit diversity techniques. In this paper, a modified switch and stay combining scheme is proposed for a Q/V band feeder link, but its performance is also evaluated over an end-to-end satellite link. The proposed scheme is pragmatic and has close to optimal performance with notably lower complexity.

Adaptive Routing Strategies in IEEE 802.16 Multi-Hop Wireless Backhaul Networks Based On Evolutionary Game Theory

The high frequency segment (10-66 GHz) of the IEEE 802.16 standard seems promising for the implementation of wireless backhaul networks carrying large volumes of Internet traffic. In contrast to wireline backbone networks, where channel errors seldom occur, routing decisions in IEEE 802.16 networks are conditioned by wireless channel impairments rather than by congestion, exclusively. This renders a cross-layer routing approach between the routing and the physical layers more appropriate during fading periods. In this paper, an adaptive cross-layer routing scheme is presented based on the selection of the most reliable path in terms of packet error ratio (unipath routing). The paper argues that routing Internet traffic through wireless backhaul networks is modeled more realistically employing evolutionary rather than conventional game theory. The stability of the proposed routing algorithm is proven and the dependence of the speed of convergence on various physical layer parameters is investigated. Is is also shown that convergence may be further accelerated by increasing the amount of information from the physical layer, specifically the physical separation between the alternative paths provided to the routing layer.

Applicability of MIMO to satellite communications

SUMMARY This paper presents achievements of an on-going activity where the applicability of MIMO to satellite communications with Digital Video Broadcasting – Satellite services to Handhelds as the key application is studied. The potential satellite and hybrid satellite-terrestrial MIMO scenarios are described, and the applicable MIMO schemes for each scenario are selected. The performance of the MIMO schemes was studied by performing comprehensive computer simulations, and the main results are presented in this paper. Copyright

Space-Frequency Coding for Dual Polarized Hybrid Mobile Satellite Systems

An increasing number of hybrid mobile systems comprising a satellite and a terrestrial component are becoming standardized and realized. The next generation of these systems will employ higher dimensions adopting multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) techniques. In this work, we build upon recent studies of dual polarization MIMO for each component and propose the use of full-rate full-diversity (FRFD) codes adopting a space-frequency paradigm. We also propose a scheme taking advantage of the separation between the subcarriers to enhance the coding gain. By critically assessing the different options for the 4 transmit, 2 receive hybrid scenario taking into account system and channel particularities, we demonstrate that the proposed scheme is a solution for enhancing the performance of next generation hybrid mobile satellite systems.