MLSE and Spatio-Temporal Interference Rejection Combining with Antenna Arrays

By using multiple receiving antennas and modeling cochannel interference (CCI) together with the noise as additive temporally white Gaussian noise with some spatial color, CCI may be suppressed. This paper proposes spatio-temporal interference rejection combining by modeling the CCI and noise as an autoregressive Gaussian process. In this way, the joint spatial-temporal properties of the CCI may be taken into account. A training sequence based estimator is proposed, and simulations show large gains in CCI rejection as compared to only spatial processing for small antenna arrays in interference limited GSM urban scenarios. An example with data collected with a dual polarized antenna in a suburban environment is also presented. 1 INTRODUCTION The use of wireless communication systems has undergone a rapid growth during the last decade. The physical limitations of the radio channel and the limited radio spectrum makes it non-trivial to meet the demands on higher data rates, quality and ..

Spatial Signature Estimation for Uniform Linear Arrays with Unknown Receiver Gains and Phases

The problem of spatial signature estimation using a uniform linear array with unknown receiver gain and phase responses is studied. Sufficient conditions for simultaneously iden- tifying the spatial signatures and the calibration parameters are derived, and a closed form ESPRIT-like estimator is proposed. The performance of the method is investigated by means of simulations, and on experimental data collected with an antenna array in a suburban en- vironment. The results show that the absence of receiver calibration is not critical for uplink signal waveform estimation using a plane wave model

A Generalized Array Manifold Model for Communication Channels with Local Scattering

In this paper, we propose the use of a generalized array manifold for parameterized spatial signature estimation in wireless communication channels with local scattering. The array manifold commonly used for point sources is generalized to include linear combinations of the nominal array response vectors and their derivatives. The motivation behind this idea is to obtain better estimates of the spatial signatures for direction of arrival (DOA) based signal waveform estimation. The estimators proposed exploit the orthogonality between the so-called noise and signal subspaces, leading to a separable solution for the derivative coefficients. As a result, a search is required for the DOAs only. For uniform linear arrays, the spatial signatures are shown to be approximately Vandermonde vectors with damped modes, and a closed-form estimator such as ESPRIT may be used in this case. Simulation examples are included to compare the signal estimation performance obtained using the proposed genera..

Adherence to anti-seizure medications in the Swedish Prospective Regional Epilepsy Database and Biobank for Individualized Clinical Treatment (PREDICT)

The aim of this study was to describe the extent of, and risk factors for, non-adherence to anti-seizure medications (ASMs) in adult people with epilepsy (PWE) in Sweden.A cross-sectional multi-centre study was performed of PWEs in western Sweden, with data from medical records, and a questionnaire filled in by the participants including self-reports on how often ASM doses had been forgotten during the past year. Participants were categorized into adherent if they forgot at 0–1 occasion, and non-adherent if they forgot at 2–10 or >10 occasions. Demographic and clinical factors were compared by Chi2- or Fisher’s test and a logistic regression model was used to find risk factors for non-adherence.In the cohort of 416 PWE aged median 43, IQR 29–62 years, 398 patients were prescribed ASM treatment at inclusion, and 39 % (n = 154) were in the non-adherent group. Significant factors in the multivariable analysis were: younger age, seizure freedom the past year, valproate treatment and experiencing side effects.The rate of self-reported non-adherence was high, illustrating a need for continuous focus on fundamental aspects of epilepsy care. The identified risk factors could enable quality improvement projects and patient education to be directed to those at risk of non-adherence

On Spatio-Temporal Interference Rejection Combining with Antenna Arrays

In this work, space-time processing for co-channel interference (CCI) reduction and intersymbol interference (ISI) equalization with antenna arrays is studied. As compared to spatial-only processing, the space-time processing proposed takes the temporal correlation of the CCI into account by modeling the noise and CCI as a Gaussian vector valued autoregressive process. This is a good approximation in interference limited scenarios and suitable for implementation with a maximum likelihood sequence estimator. For spatial-only processing, the time dispersion of the CCI may limit the performance, whereas this is not the case with space-time processing. Space-time processing provides large gains in interference rejection as compared to spatial-only processing when time dispersion increases the dimension of the subspace to which the interference is confined. 1. INTRODUCTION To meet the increasing demands on higher data rates, quality, coverage and capacity of wireless systems, the use of an..

Modified Array Manifold for Signal Waveform Estimation in Wireless Communications

In wireless communication scenarios, local scatterers in the vicinity of the sources cause angular spreading. Herein, a parameterization of the spatial signature in the presence of local scattering is presented which applies to uniform linear arrays (ULAs). The spatial signature is shown to be approximately a Vandermonde vector for a ULA in environments with small angular spread. An estimator of the spatial signature is formulated based on ESPRIT. For a simple signal waveform estimator, the gain may be considerable in scenarios with multiple sources, as compared with using the ideal manifold parameterized by direction of arrival (DOA). 1. Introduction The use of antenna arrays at base stations in wireless communication systems has received substantial interest, see e.g. [3, 9]. Increased range and decreased co-channel interference may be obtained, leading to increased coverage and increased capacity of the system. The problem of uplink (mobile to base) signal waveform estimation in en..

A Generalized Array Manifold Model for Local Scattering in Wireless Communications

In wireless communication scenarios, local scatterers in the vicinity of the mobile sources cause angular spreading. As a result, the spatial signatures will not belong to the conventional array manifold parameterized by direction of arrival (DOA) alone. In this paper, a parameterized model for spatial signatures applicable in scenarios with local scattering is presented. Several algorithms that exploit this model are proposed, and the performance of signal waveform estimators using the model is investigated via simulations. It is demonstrated that considerable gain may result as compared with using the conventional plane wave model. 1. INTRODUCTION The use of antenna arrays as a tool for improving coverage, reducing interference, and increasing capacity in wireless communications systems has recently attracted significant interest [6]. For the uplink (remote to base) portion of the system, signals can be separated at the array based on knowledge of their spatial or temporal "signatu..