Walid Hakimi

A Generalised Wideband Space-Time MIMO Channel Simulator Based on the Geometrical Multi-Radii One-Ring Model

This paper extends the geometrical one-ring multi- input multi output (MIMO) channel model for a frequency flat fading process in a land mobile radio system with respect to frequency-selectivity. Our approach enables the design of efficient simulation models for space-time MIMO channels under isotropic scattering conditions for any numbers of transmit and receive antennas. A simulation study is performed into the space- time cross correlation to gain understanding of the modification of some relevant parameters. A conventional four transmit four receive 4 x 4 MIMO radio channel is analyzed.

Analysis of Full Volterra and Sparse Volterra Nonlinear Equalization for Downlink LTE System

In this work, we propose Full Volterra and Sparse Volterra channels equalization algorithms for downlink LTE system. For estimation purpose, the LTE standard provides known data as pilot symbols and exploits them through a coherent detection to improve system performance. The references symbols location is similar to diamond pattern through time and frequency domain. Our goal is to show how to use the Full Volterra and Sparse Volterra equalizers over frequency domain in order to mitigate linear and nonlinear effects introduced by power amplifier and multipath channel. Downlink LTE Performances System in term of BLER, EVM (%) and Throughput versus SNR are presented and discussed. Then we compare our results with basic RLS equalizer curves. Moreover, it is shown that the Full Volterra and Sparse Volterra models can significantly reduce interferences and nonlinear effects and consequently improve the performances of LTE Downlink System.

Analysis of full volterra nonlinear equalizer for downlink LTE system

In this work, we propose a Full Volterra channel equalization for downlink LTE system. For estimation purpose, the LTE standard provides known data as pilots symbols and exploits them through a coherent detection to improve system performance. These drivers are placed in a hybrid way to cover up both time and frequency domain. Our aim is to precise how to adapt the Full Volterra technique to the LTE standard in order to compensate linear and nonlinear effects introduced by power amplifier and multipath channel. We present the comportment of Full Volterra equalizer in term of BLER, EVM (%) and Throughput versus SNR. Then we compare our results with basic RLSequalizercurves. Moreover, it is shown that the Full Volterra model can significantly reduce interferences and nonlinear effects and consequently improves the performances of LTE Downlink System.

Analysis of Wiener-Hammerstein equalizer for downlink LTE system

We propose a Wiener-Hammerstein (W-H) channel estimation algorithm for Long-Term Evolution (LTE) systems. The LTE standard provides known data as pilot symbols and exploits them through coherent detection to improve system performance. These drivers are placed in a hybrid way to cover up both time and frequency domain. Our aim is to adapt the W-H equalizer (W-H/E) to LTE standard for compensation of both linear and nonlinear effects induced by power amplifiers and multipath channels. We evaluate the performance of the W-H/E for a Downlink LTE system in terms of BLER, EVM and Throughput versus SNR. Afterwards, we compare the results with a traditional Least-Mean Square (LMS) equalizer. It is shown that W-H/E can significantly reduce both linear and nonlinear distortions compared to LMS and improve LTE Downlink system performance.

MPIC and space-time rake detectors on MIMO HSDPA system using generalized Alamouti codes

It is well known that HARQ technique generates delays du to the retransmissions. Thus, the high speed real time services quality, in High Speed Downlink Packet Access (HSDPA), depends on the number of the retransmissions. Motivated by the important diversity that multiple transmitting antennas and multiple receiving antennas (MIMO) can provide, we study the possibility to avoid HARQ retransmissions by using evolved detector as Multipath Parallel Interference Canceller (MPIC) associated to MIMO. Based on generalized Alamouti codes, then, we demonstrate that MIMO 4×4 + MPIC detector could give better performance than MIMO 2×2 Space-time Rake taking into account the HARQ context.