4 research outputs found
Joint array combining and MLSE for single-user receivers in multipath Gaussian multiuser channels
The well-known structure of an array combiner along with a maximum likelihood sequence estimator (MLSE) receiver
is the basis for the derivation of a space-time processor presenting
good properties in terms of co-channel and intersymbol interference
rejection. The use of spatial diversity at the receiver front-end
together with a scalar MLSE implies a joint design of the spatial
combiner and the impulse response for the sequence detector. This
is faced using the MMSE criterion under the constraint that the
desired user signal power is not cancelled, yielding an impulse response
for the sequence detector that is matched to the channel and
combiner response. The procedure maximizes the signal-to-noise
ratio at the input of the detector and exhibits excellent performance
in realistic multipath channels.Peer Reviewe
Performance Analysis of Wireless Systems with Doubly Selective Rayleigh Fading
Theoretical error performances of wireless communication systems suffering from both doubly selective (time varying and frequency selective) Rayleigh fading and sampler timing offset are analyzed in this paper. Single-input-single-output systems with doubly selective fading channels are equivalently represented as discrete-time single-input-multiple-output (SIMO) systems with correlated frequency-flat fading channels, with the correlation information being determined by the combined effects of sampler timing phase, maximum Doppler spread, and power delay profile of the physical fading. Based on the equivalent SIMO system representation, closed-form error-probability expressions are derived as tight lower bounds for linearly modulated systems with fractionally spaced equalizers. The information on the sampler timing offset and the statistical properties of the physical channel fading, along with the effects of the fractionally spaced equalizer, are incorporated in the error-probability expressions. Simulation results show that the new analytical results can accurately predict the error performances of maximum-likelihood sequence estimation and maximum a posteriori equalizers for practical wireless communication systems in a wide range of signal-to-noise ratio. Moreover, some interesting observations about receiver oversampling and system timing phase sensitivity are obtained based on the new analytical results
Récepteurs SIMO MLSE Widely Linear - Structures et performances en présence d’interférences non circulaires
International audienc
A combined channel-modified adaptive array MMSE canceller and viterbi equalizer
In this thesis, a very simple scheme is proposed which couples a maximum-likelihood sequence estimator (MLSE) with a X-element canceller. The method makes use of the MLSE\u27s channel estimator to modify the locally generated training sequence used to calculate the antenna array weights. This method will increase the array\u27s degree of freedom for interference cancellation by allowing the dispersive, desired signal to pass through the array undisturbed. Temporal equalization of the desired signal is then accomplished using maximum-likelihood sequence estimation. The T-spaced channel estimator coefficients and the array weights are obtained simultaneously using the minimum mean square error criteria. The result is a X-element receiver structure capable of canceling X- 1 in-band interferences without compromising temporal equalization