Analysis of coded noncoherent transmission in DS-CDMA mobile satellite communications

The paper analyzes possible transmission schemes for satellite personal communication systems adopting Low/ Medium-Earth orbit (LEO/MEO) constellations and DirectSequence Code Division Multiple Access (DS-CDMA) in the presence of fading and shadowing, the statistics of which are functions of the satellite elevation angle. In particular, the performance of M-ary Walsh-Hadamard orthogonal (MWHO) convolutionally coded DS-CDMA over a Rice-log-normal fading channel is analyzed in depth, and compared to the simpler coded differential BPSK (DBPSK) scheme. Optimization of the performance/complexity tradeoff in the metric computation for soft inputs to the Viterbi decoder is addressed. Upper bounds on the error probability without or with satellite diversity and equal gain combining are evaluated considering different coding rates. The effect of correlated fading is also taken into account via simulation. Among the various results, it is shown that the optimal coding rate is a function of the satellite elevation angle and of the diversity order, that the loss for using DBPSK instead of MWHO is in the range 1-1.4 dB, and that interleaving depth is a critical parameter

Analysis of coded noncoherent transmission in DS-CDMA mobile satellite communications

The paper analyzes possible transmission schemes for satellite personal communication systems adopting Low/ Medium-Earth orbit (LEO/MEO) constellations and DirectSequence Code Division Multiple Access (DS-CDMA) in the presence of fading and shadowing, the statistics of which are functions of the satellite elevation angle. In particular, the performance of M-ary Walsh-Hadamard orthogonal (MWHO) convolutionally coded DS-CDMA over a Rice-log-normal fading channel is analyzed in depth, and compared to the simpler coded differential BPSK (DBPSK) scheme. Optimization of the performance/complexity tradeoff in the metric computation for soft inputs to the Viterbi decoder is addressed. Upper bounds on the error probability without or with satellite diversity and equal gain combining are evaluated considering different coding rates. The effect of correlated fading is also taken into account via simulation. Among the various results, it is shown that the optimal coding rate is a function of the satellite elevation angle and of the diversity order, that the loss for using DBPSK instead of MWHO is in the range 1-1.4 dB, and that interleaving depth is a critical parameter

Aspects for system trade-off in mobile and personal satellite communications

Several original system configurations are being studied to provide in the near future a new generation of mobile and personal satellite services. Among them technical differences are more than similarities and system trade-offs are crucial. The paper introduces and discusses the main parameters for system trade-offs: system spectrum efficiency and outage probability. Then it considers both single-channel per carrier and code division multiple access techniques, in multi-satellite and multi-spot scenarios, and it provides some quantitative results achieved through combined analysis and simulation

Interference analysis in satellite cellular systems

In next generation mobile satellite systems very high spectrum efficiency will be a primary objective. High spectrum efficiency is often related to a significant amount of co-channel and/or adjacent channel interference. Therefore, system design should in general include consideration of both interference and noise effects. Interference evaluation in a mobile satellite cellular system is different from the case of a terrestrial system due to the presence of the on-board antenna which acts as a spatial filter. The paper addresses the modeling of interference in single and multi-satellite cellular system and provides some results of the analysi

Comparison of low and medium orbit systems for future satellite personal communications

Several satellite systems have been recently proposed for provision of mobile and personal services via Low Earth Orbits (LEO) or Medium Earth Orbits (MEO). Comparison of different system alternatives is difficult due to the complex interaction between system elements. This paper concentrates on a comparison of LEOs and MEOs on the basis of a few important parameters that impact telecommunications service quality. The considered factors are coverage areas, handover times and link unavailability. The results of the analysis have been achieved for various study cases, selected among satellite systems recently presented in the literature

An approach to transmission performance evaluation for satellite systems adopting non-geostationary constellations

In this paper we illustrate an approach suitable for the transmission performance evaluation for satellite systems adopting non-geostationary orbit constellation. Main elements in the analysis and design of such systems and stem from satellite mobility and multi-spot coverage per satellite

Analysis of performance and possible trends of CDMA cellular systems

The paper addresses the spectrum efficiency issue of cellular CDMA, and system capacity, in particular assuming the IS-95 standard as a reference. System capacity is evaluated by means of a new analytical approach, and comparison with simulation results are shown. Several channel impairments are taken into account, including lognormal shadowing, Rayleigh fading, and imperfect power control. Among various results, it is confirmed that tight power control (within 1 dB) is a fundamental feature of this system. Then, we show how the CDMA may evolve in future microcellular scenarios to have a system able to optimally blend sources of traffic with different mobility (i.e., vehicular and personal)