| Adaptive methods for performing multiuser demodula-tion in a Direct-Sequence Spread-Spectrum Multiple-Access (DS/SSMA) communication environment are investigated. In this scenario, the noise is characterized as being the sum of the interfering users' signals and additive Gaussian noise. The optimal receiver for DS/SSMA systems has a complexity that is exponential in the number of users. This ...

The detection strategy usually denoted optimal multiuser detection is equivalent to the solution of a (0, 1)-constrained maximum-likelihood (ML) problem, a problem which is known to be NP-hard. In contrast, the unconstrained ML problem can be solved quite easily and is known as the decorrelating detector. In this paper, we consider the constrained ML problem where the solution vector is restric...

A two-stage adaptive multiuser detector in an additive white Gaussian noise code-division multiple-access channel is proposed and analyzed. Its first stage is an asynchronous one-shot decorrelator which in terms of computational complexity only requires inversion of symmetric matrices for all users. In addition, the inversions can be done in parallel, and the computed results for one user can b...

Performance analysis of the minimum-mean-squareerror (MMSE) linear multiuser detector is considered in an environment of nonorthogonal signaling and additive white Gaussian noise. In particular, the behavior of the multiple-access interference (MAI) at the output of the MMSE detector is examined under various asymptotic conditions, including: large signal-tonoise ratio; large near–far ratios; a...

A variety of techniques have been proposed to train machine learning classifiers that are independent a given feature. While this can be an essential technique for enabling background estimation, it may also useful reducing uncertainties. We carefully examine theory uncertainties, which typically do not statistical origin. will provide explicit examples two-point (fragmentation modeling) and co...

Chaos based communications have drawn increasing attention over the past years. Chaotic signals are derived from non-linear dynamic systems. They are aperiodic, broadband and deterministic signals that appear random in the time domain. Because of these properties, chaotic signals have been proposed to generate spreading sequences for wide-band secure communication recently. Like conventional DS...

We show that in a K transmit N receive antenna coherent narrowband communication system employing a decorrelating decision feedback detector (D-DFD, also known as BLAST), the diversity order of the joint error rate (JER) isN K+1. We derive the exact joint error rate (JER) as well as the symbol error rate (SER) without making the perfect feedback assumption and show that the diversity order of t...