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Abstract
In this paper, an effective multiuser detection (MUD) is proposed for direct sequence ultrawideband- (DS-UWB-) based space formation flying systems. The proposed method called GMM-MUD is based on Gaussian mixture models (GMMs) to suppress multiple access interference. The GMM describes probability distributions of the hypothesis testing problem which is used for bit classification. To reveal the difference between correct bits and error bits, the preprocessing operation applies a mapping function based on optimal multiuser detection. The parameters of GMM are estimated by using expectation-maximization (EM) algorithm. EM algorithm employs iterative operation to simplify the complexity of maximum likelihood estimation method and considers the mapping values of received bits as the observations. Simulation results demonstrate that the proposed GMM-MUD algorithm achieves good performances in terms of bit error rate performance, user capacity, and near-far resistance. Moreover, the computational complexity is low enough for space formation flying applications.
Highlights
In recent years, space formation flying has drawn a great deal of interests for missions in and beyond Lower Earth Orbit (LEO) [1]
After analyzing the EM algorithm, we provide a realization of the proposed Gaussian mixture models (GMMs)-multiuser detection (MUD) algorithm shown in Algorithm 1. e mapping values obtained by preprocessing are considered as the observations for EM algorithm. e parameters are estimated through iteration operation
E GMM-MUD algorithm is employed to an asynchronous multiuser binary phase shift keying (BPSK) DS-UWB system for space formation flying
Summary
Space formation flying has drawn a great deal of interests for missions in and beyond Lower Earth Orbit (LEO) [1]. MAI cannot be completely suppressed by using DSMA scheme owing to the incomplete orthogonality of PN codes and large user number Concerning this problem, multiuser detection (MUD) is applied as an effective MAI suppression method at receivers. We propose a Gaussian mixture model(GMM-) based multiuser detection algorithm which is called GMM-MUD for DS-UWB-based space formation flying systems. E matched filter can be considered as the simplest multiuser detector termed as single-user detection (SUD) with the multiple access scheme applied to communication systems [10]. In this case, the desired signal can be detected by using the correlation between the desired signal and the corresponding template signal, and the interfering signals are considered as noise. The tradeoff problem between computational complexity and MUD performance is always the research objective
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