Pierre-Francois Morlat

Coupled simulation-measurements platform for the evaluation of frequency reuse in the 2.45 ghz ISM band for multimode nodes with multiple antennas

We address the problem of efficiently evaluating performance of concurrent radio links on overlapped channels. In complex network topologies with various standards and frequency channels, simulating a realistic PHY layer communication is a key point. The presented coupled simulation-measurement platform offers a very promising way of rapidly modelling and validating effective performance of multimode, multichannel and multiantenna radio nodes. An accurate analysis of radio channel is performed and then realistic performance with or without antenna processing is shown, verifying theoretical performance. Finally, available performance of concurrent communications on overlapped channels is exposed, showing that this approach is viable to enhance network capacity.

On the Compensation of RF Impairments with Multiple Antennas in SIMO OFDM Systems

This paper provides an analysis of the impact of radio frequency (RF) front end impairments (I/Q gain and phase imbalance, phase noise, non-linear distortion and direct current offset) on the performance of a single input multiple output orthogonal frequency division multiplexing (SIMO OFDM) receiver. We developed a new estimation/compensation scheme to jointly compensate for the effect of multipath and RF non- idealities on baseband signals in the special case of Zero-IF receivers. Some first results illustrating this approach are presented for a 4 antenna 802.11 g receiver with the SMI algorithm and with or without IQ imbalance, as well as BER curves for different phase noise models.

Global System Evaluation Scheme for Multiple Antennas Adaptive Receivers

This paper describes a global system approach to easily develop, simulate and validate a multi-antennas receiver structure. Our aim is to offer a rapid evaluation for future wireless systems, including promising techniques such as SIMO or MIMO, software defined radio (SDR), OFDM and interference cancellation. A particular focus is on the impact of RF front-ends characteristics on the effective performances of a receiver in a realistic environment. A complete connected solution based on Agilent Technologies tools is presented, combining simulations and measurements with realistic conditions. This testbed allows a direct evaluation of all parts of a wireless link with multiple antennas. For instance IQ imbalance and phase noise influence on a four antennas 802.11g receiver is herein exposed

IQ Imbalance Reduction in a SMI Multi-Antenna Receiver by Using a Code Multiplexing Front-End

In this paper, we address the IQ imbalance sensibility of the code multiplexing front-end architecture. This innovative architecture has been recently proposed in order to reduce the analog complexity of an antenna diversity receiver front-end. An interesting characteristic of this structure is that the resulting IQ imbalance is equal for each received baseband signal. Associated with Single Matrix Inversion algorithm, this property ensures a high IQ imbalance robustness. A global antenna diversity system including analog front-end and digital processing has been implemented in order to perform simulation validation. Results show that the bit error rate does not increase significantly with the multiplexing and this increase is compensated for a high IQ imbalance.

Performance validation of a multi-standard and multi-antenna receiver

This paper assesses the efficiency of a multi standard and multi antenna receiver using simulation and test measurements in a real propagation environment. A multi-standard and multi-antenna receiver is firstly designed with the ADS© software. Secondly, the performance of this system is evaluated with several multi-antenna algorithms, under real radio propagation conditions depending on the standard we choose to deal with. At this time the receiver can run with 802.11b and 802.11g standards in a 36 MHz bandwidth. Some first results are presented using multi antenna algorithm in a receiver dealing with two 802.11g or 802.11b transmission on overlapped communication channels.

Structure and implementation of a SIMO multi-standard multi-channel SDR receiver

This article presents the structure of a multi- antenna multi-channel and multi-standard receiver based on software defined radio (SDR) concept. At this time our work is focused on 802.11 g and 802.11 b signals cohabiting in a 40 MHz frequency bandwidth around the 2.4 GHz RF carrier frequency. Using classical single input multiple output (SIMO) processing, these incoming signals are combined to increase transmission performances and to mitigate fading effect. Simulated and measured results of our structure are given and a description of the real proposed architecture is detailed.

Impact of RF front-end non-idealities on performances of SIMO-OFDM receiver

Today, in OFDM systems, zero-IF receivers are very appealing, because they avoid costly IF filters. However, this very popular architecture implies IQ demodulation at RF and thus introduces new drawbacks and large performance degradations. Its therefore very important to study the impact of RF front-end non- idealities on performances of OFDM receiver. Especially, its necessary to investigate the influence of I/Q gain and phase imbalance, local oscillator phase noise and non-linear distortion. In this paper, 802.11g standard has been studied in terms of bit error rate (BER) and constellation of each subcarrier. Simulated and measured results have been studied in the four arms SMI (sample matrix inversion) as compared with a single antenna receiver. Two channel conditions, AWGN channel and multipath channel (taking account the fading correlation), have been modelled and studied to quantify WLAN performance degradations but also to evaluate the efficiency of a multi element antennas system at the receiver to improve significantly the performances of a wireless system. Advanced design system (ADS - Agilent Technologies) software and a radio test-bed have been used in this work.