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Rician Fading Channels (rician + fading_channel)

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Engineering	100%

Selected Abstracts

Blind equalization of space-time-turbo trellis coded/continuous phase modulation over Rician fading channels

EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 5 2004
Osman N. Ucan
In this paper, to improve bit error performance and bandwidth efficiency, we combine space-time block codes (STBC), turbo trellis codes and continuous phase modulation and denote space-time-turbo trellis coded/continuous phase modulation (ST-TTC/CPM). For high data transmission over wireless fading channels, STBC provide the maximal possible diversity advantage for multiple decoding algorithms. We present continuous phase modulation (CPM) for ST-TTC signals, since CPM provides low-spectral occupancy and is suitable for power and bandwidth-limited channels. In our model, to utilize STBC efficiently, we need to estimate the channel parameters, which influence the signals having continuity property. Therefore, we develop a blind maximum likelihood channel estimation algorithm for signals propagating through a Rician fading channel. Here, Baum-Welch (BW) algorithm, based on hidden Markov model (HMM), is modified to provide computationally efficient channel parameter estimation. We also investigate the performance of ST-TTC/CPM in the case of no channel state information (CSI) for various Rician parameters K and Doppler frequency. Copyright © 2004 AEI. [source]

Analyzing GPS signals to investigate path diversity effects of non-geostationary orbit satellite communication systems

INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 6 2002
Hsin-Piao Lin
Abstract The concept behind path diversity is that a user who can access several satellites simultaneously will be able to communicate more effectively than a user who could only access one. The success of this method depends on the environment, the satellite constellation, and diversity combining technology. This paper explores the path diversity effects of non-geostationary orbit (NGO) satellite personal communication services, for different degrees of user mobility, under various scenarios, using the constellation of the global positioning system (GPS). Measurements are taken near downtown Taipei. Three types of mobilities (fixed-point, pedestrian, and vehicular) are examined, and the switch diversity and maximum ratio combining method are applied to determine the path diversity gain and calculate bit error probability. The error probability performance of applying diversity schemes in coherent binary phase shift keying (BPSK) and non-coherent differential phase shift keying (DPSK) modulations over Rician fading channels are also analysed and evaluated by using the characteristic function method. The results show that fading can be significantly reduced and diversity greatly increased. A significant diversity gain and improvement in bit error rate (BER) can be expected in all cases by simply applying switch diversity scheme. Besides, for the maximum ratio combining method, the results imply that summing two satellite signals suffices to increase diversity and improve the bit error rate performance. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Blind equalization of quadrature partial response-trellis coded modulated signals in Rician fading,

INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 2 2001
Hakan A. Cirpan
Abstract In this paper, a blind maximum-likelihood channel estimation algorithm is developed for quadrature partial response-trellis coded modulated (QPR-TCM) signals propagating through a Rician fading environment. A hidden Markov model (HMM) formulation of the problem is introduced and the Baum,Welch parameter estimation algorithm is modified to provide a computationally efficient solution to the resulting optimization problem. Performance analysis of the proposed method is carried out through the evaluation of bit-error probability upper bound for Rician fading channels. Also, some illustrative simulations are presented. Copyright © 2001 John Wiley & Sons, Ltd. [source]