Abstract
This paper considers a partially coherent detection of quadrature phase-shift keying (QPSK) signals in a composite generalized K (KG) fading channel. At the reception the selection combining is applied, while the branches of the combiner are not identically distributed. The extraction of the reference carrier from non-modulated pilot signal is performed in a phase-locked loop (PLL) circuit. The difference between received signal phase and extracted reference signal phase is a stochastic variable with Tikhonov probability density function. The influence of the fading parameters, the standard deviation of phase error and the number of diversity branches on the system performance is examined. The bit-error rate is used as a measure of the reception quality. Ill. 6, bibl. 17 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.115.9.746
Highlights
In mobile radio communications, due to a multipath propagation, the incoming signal at the receiver is corrupted by the fast fading effect i.e. the random fast fluctuations of the signal envelope [1, 2]
Obtained composite probability density function follows generalized K (KG) distribution, which proved to be useful in evaluating the performance of composite channels [3,4,5,6]
These parameters represent the orders of respective quadrature rules, and in Fig. 1. we investigate the values of N and K that are required to obtain results with given accuracy
Summary
Due to a multipath propagation, the incoming signal at the receiver is corrupted by the fast fading effect i.e. the random fast fluctuations of the signal envelope [1, 2]. A composite probability density function, obtained in this way, is in integral form and it is not convenient for further analysis For this reason, equivalent gamma distribution, rather than lognormal distribution, is introduced for describing slow fading effect [3,4,5,6]. In [6] a detailed performance analysis for the most important diversity receivers (SC receiver among them), operating over a composite fading channel, modelled by the KG distribution, was presented. The phase error is a difference between the phase of the incoming signal and the phase of the recovered carrier signal in the loop, and this may lead to serious degradation of system performance It is a statistical process which follows Tikhonov distribution [12,13,14].
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