RESEARCH ARTICLE
EM-Based Optimal Maximal Ratio Diversity Combiner for Constant Envelope Signals
Ahmed El-Sayed El-Mahdy*
Article Information
Identifiers and Pagination:
Year: 2009Volume: 2
First Page: 1
Last Page: 6
Publisher Id: TOSIGPJ-2-1
DOI: 10.2174/1876825300902010001
Article History:
Received Date: 12/10/2008Revision Received Date: 29/12/2008
Acceptance Date: 01/01/2009
Electronic publication date: 28/1/2009
Collection year: 2009
open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Abstract
An optimal maximal ratio combiner (MRC) based on the expectation-maximization (EM) algorithm is developed for noisy constant envelope signals transmitted over a Rayleigh fading channel. Instead of using a transmitted pilot signal with the data to estimate the combiner gains, the EM algorithm is used to perform this estimation. In the developed MRC, estimation of the transmitted data sequence is performed also by the EM algorithm. Estimation using the EM algorithm provides an iterative solution to the maximum likelihood (ML) approach. Therefore, the resulting receiver is optimum and does not suffer from the difficulties resulted from direct application of the ML procedure. One of these difficulties is the computational complexity which depends exponentially on the data sequence length. Introducing an iterative structure in the developed MRC achieves a linear computational complexity and enables efficient data extraction by the Viterbi algorithm when trellis coding is used.
