Kosai Raoof

Impact of Depolarization Effects on MIMO Polarized Wireless Configuration

On wireless communication systems, multiple-input multiple-output (MIMO) systems have dramatically the potential to improve the reliability and the performance. However, the MIMO wireless channel performance is generally affected by the antenna array configuration and environment characteristic. This paper highlights the impact of angle spread and depolarization effects on the MIMO channel capacity with a focus on 4times4 uniform linear multi-polarized antenna array. We employ a geometric scattering model based on a three-dimensional double bouncing model that takes into account the antenna configurations. We investigate the use of multi-polarization configurations that can provide capacity improvement over conventional single-polarization configurations. The single-polarization configuration is dependent on the depolarization phenomena. It is found that when low depolarization and spatial correlation effects, the capacity of single-polarization configuration behaves better than that of multi-polarization configuration.

Impact of Depolarization Phenomena on Polarized MIMO Channel Performances

The performance and capacity of multiple-input multiple-output (MIMO) wireless channels are limited by the spatial fading correlation between antenna elements. This limitation is due to the use of mono polarized antennas at receiver and transmitter sides. In this paper, in order to reduce the antenna correlation, the polarization diversity technique is employed. Although the spatial antenna correlation is attenuated for multi-polarization configurations, the cross-polar components appear. This paper highlights the impact of depolarization effect on the MIMO channel capacity for a 4a#215;4 uniform linear antenna array. We assume that the channel is unknown at the transmitter and perfectly known at the receiver so that equal power is distributed to each of the transmit antennas. The numerical results illustrate that for low depolarization and spatial correlation, the capacity of single-polarization configuration behaves better than that of multi-polarization configuration.

Novel Joint Chip Sampling and Phase Synchronization Algorithm for Multistandard UMTS Systems

CDMA Timing and phase offsets tracking remain as one of considerable factors that influence the performances of communication systems. Many algorithms are proposed to solve this problem. In general, these solutions process separately the chip sampling offset and phase rotation. In addition, most of proposed solutions can not assure a compromise between robustness criteria and low complexity for implementation in real time applications. In this paper we present an efficient algorithm for chip sampling and phase synchronization. This algorithm allows estimating and correcting jointly in real time, sampling instant and phase errors. The robustness and the low complexity of this algorithm are evaluated, firstly by simulation and then tested by real experimentation for UMTS standard. Simulation results show that the proposed algorithm provides very efficient compensation for sampling clock offset and phase rotation. A real time implementation is achieved, based on TigerSharc DSP, while using a complete UMTS transmission-reception chain. Experimental results show robustness in real conditions.

Space-Time-Delay Correlation of 3-D MIMO Channel Model

Abstract-In this paper, we present a 3-D MIMO channel model for wideband communication based on the geometric scattering channel model. The space-time-delay correlation is also derived and presented in the case of non-isotropic scattering distribution. We are interested in two MIMO array systems: uni-polarized antenna array and bi-polarized antenna array. For the bi-polarized MIMO systems, the polarizations of all the used antennas are imperfectly orthogonal. Thus the correlation between antennas can be occurred.

Book Recommendation: Advanced MIMO Systems

Book Recommendation: Advanced MIMO Systems Kosai Raoof and Huaibei Zhou Scientific Research Publishing, 2009 234 pages ISBN: 978-1-935068-02-0 Paperback (US

MIMO Channel Capacity with Polarization Diversity and Power Allocation Technique

80.00) E-book (US

Digital joint phase and sampling instant synchronisation for UMTS standard

100.00) Order online: www.scirp.org/book Order by email: bookorder@scirp.org

Antenna Selection for MIMO Systems in Correlated Channels with Diversity Technique

This paper considers the use of 4 × 4 multiple-input multiple-output (MIMO) antenna arrays for improving the mutual information with and without polarization diversity. The authors focus on the benefits offered by a combination of spatial and polarization diversity techniques. In this paper, are taken in consideration the cases where the channel state information (CSI) is known or unknown to transmitter for low signal to noise ratios (SNR) in the presence of low and high spatial correlation. The cumulative distribution function (CDF) of the mutual information is studied. We also examine the impact of cross polarization discrimination (XPD) on the mean mutual information of MIMO systems.

Correlation Effects and Channel Capacities for MIMO Polarization Diversity

In asynchronous direct-sequence code division multiple access (DS-CDMA) receivers, one of the major functions is timing and phase synchronisation. Many proposed solutions treat these functions separately. In this paper we present a new joint synchronisation solution for UMTS standard. This solution is based on a digital delay and phase looked loops. In addition this implementation is programmable for the two modes of UMTS (FDD and TDD) with variable over-sampling factor. It has tested in real time on TigerSHARC DSP.