Jean Philippe Kermoal’s research while affiliated with Aalborg University and other places

Theoretical and experimental studies of multiple-input/multiple-output (MIMO) radio channels are presented. A simple stochastic MIMO model channel has been developed. This model uses the correlation matrices at the mobile station (MS) and base station (BS) so that results of the numerous single-input/multiple-output studies that have been published in the literature can be used as input parameters. The model is simplified to the narrowband channels. The validation of the model is based upon data collected in both picocell and microcell environments. The stochastic model has also been used to investigate the capacity of MIMO radio channels, considering two different power allocation strategies, water filling and uniform and two different antenna topologies, 4×4 and 2×4. Space diversity used at both ends of the MIMO radio link is shown to be an efficient technique in picocell environments, achieving capacities within 14 b/s/Hz and 16 b/s/Hz in 80% of the cases for a 4×4 antenna configuration implementing water filling at a SNR of 20 dB.

This article summarizes the main achievements of the Multi-Element Transmit and Receive Antennas (METRA) Project, an IST research and technological development project carried out between January 2000 and June 2001 by Universitat Politecnica de Catalunya, the Center for Personkommunikation of Aalborg University, Nokia Networks, Nokia Mobile Phones, and Vodafone Group Research and Development. The main objective of METRA was the performance evaluation of multi-antenna terminals in combination with adaptive antennas at the base station in UMTS communication systems. A MIMO channel sounder was developed that provided realistic multi-antenna channel measurements. Using these measured data, stochastic channel models were developed and properly validated. These models were also evaluated in order to estimate their corresponding channel capacity. Different MIMO configurations and processing schemes were developed for both the FDD and TDD modes of UTRA, and their link performance was assessed. Performance evaluation was completed by system simulations that illustrated the benefits of MIMO configurations to the network operator. Implementation cost vs. performance improvement was also covered by the project, including the base station and terminal manufacturer and network operator viewpoints. Finally, significant standards contributions were generated by the project and presented to the pertinent 3GPP working groups

A stochastic MIMO radio channel considering (i) polarization diversity and (ii) unbalanced branch power ratio (BPR) is being validated by comparing Monte-Carlo simulations and experimental results using the eigenanalysis as benchmark. Based on results generated by the model, the influence of the BPR on the power gain of the parallel subchannels is presented.

MIMO (Multiple Input Multiple Output) channels are known for some time now to offer either greater link gains or better spectral efficiency, depending on the correlation level of the scattering environment [1]. However, the benefits to be gained from the use of smarter antenna topologies do definitely not rule out gains available by the use of other techniques, such as polarisation diversity. The present paper investigates the benefits offered by this technique in an outdoor-to-indoor microcell scenario. More specifically, it corroborates previous conclusions drawn from measurements presented in [2] with the help of simulation results. These results have been produced using the COSSAP ® implementation of a stochastic model of MIMO radio channels developed in the framework of European-funded IST (Information Society Technologies) METRA (Multi Element Transmit and Receive Antenna) project [3]. Moreover, two power allocation strategies are applied to the scenario under study and their performance is compared.

This paper presents analysis of MIMO radio channel mea-surements. A description of both the measurement set-up and the picocell environment is given. The correlation properties of the MIMO radio channel are investigated considering differ-ent diversity techniques such as spatial, polarisation and joint spatial and polarisation diversity techniques. It is shown that a combination of space and polarisation diversity is an attractive solution for achieving compact MIMO implementation espe-cially when a large number of antenna ports is considered. The issue of unbalanced Branch Power Ratio (BPR) is addressed and its influence on the power gain of the potential subchannel generated by the MIMO concept is analysed. Keywords MIMO radio channel measurement, joint spatial and polarisa-tion diversity, eigenanalysis.

The multi-element antenna arrays concept with M elements at the mobile station (MS) in combination with N elements at the base station (BS) is experimentally investigated. Forschini (1996) has shown very promising results to improve the spectral efficiency in a rich scattering environment. The performance of the M×N concept is evaluated in terms of the number of independent parallel channels, diversity gain and total capacity in an outdoor to indoor microcellular environment. It is shown that the eigenanalysis provides a tool to describe the effective number of parallel channels in a multi-element array configuration. Practical results on spectral efficiency are presented for different antenna setups applied to different propagation scenarios. Also it is shown that polarization diversity is an attractive solution to achieve decorrelated antenna elements and subsequently provide a more robust system in terms of spectral efficiency within the microcell. Results show that a total capacity of 27.9 b/s/Hz can be achieved for an uncorrelated propagation environment and 17 b/s/Hz for a correlated one with a mean signal to noise ratio (SNR) of 30 dB in the case of a 4×4 antenna set-up

The present paper describes the set-up for the measurement of MIMO (multi-input-multi-output) radio channels as part of the European project METRA (Multi Element Transmit and Receive Antenna). Inputs for the stochastic model described by Pedersen, Andersen, Kermoal and Mogensen (see IEEE Vehicular Technology Conference VTC 2000 Fall, Boston, USA, 2000) are extracted from the measurement results and fed into a COSSAP(R) block implementing this model. A good matching between the eigenanalysis performed on both measured and simulated signals is shown

A simple framework for Monte Carlo simulations of a multiple-input-multiple-output radio channel is proposed. The derived model includes the partial correlation between the paths in the channel, as well as fast fading and time dispersion. The only input parameters required for the model are the shape of the power delay spectrum and the spatial correlation functions at the transmit and receive end. Thus, the required parameters are available in the open literature for a large variety of environments. It is furthermore demonstrated that the Shannon capacity of the channel is highly dependent on the considered environment

The present paper describes the set-up for the measurement of MIMO (Multi-Input-Multi-Output) radio channels as part of the European IST (Information Society Technologies) project METRA (Multi Element Transmit and Receive Antenna). Exploitation of the measurements showed that 0.4λ separation, where λ is the wavelength, between the elements of the antenna array is sufficient to have them decorrelated even in a LOS scenario. Moreover a gain of 18 dB at 10% outage can be achieved using a 4×4 MIMO set-up. Inputs for the stochastic model described in [2] are extracted from the measurement results and fed into a COSSAP  block implementing this model. A good matching between the eigenanalysis performed on both measured and simulated signals is shown.

This document presents a simple framework for Monte-Carlo simulations of a multiple-input-multiple-output (MIMO) radio channel. A stochastic model including the partial correlation between the paths in the MIMO channel, as well as fast fading and time dispersion is proposed. Its implementation in a COSSAP ® primitive model is described. Simulations verify the features of this primitive model. However, the stochastic model still needs to be validated by comparison with results of measurement campaigns currently in progress [1,2]. This COSSAP ® block will later help to investigate combined transmit/receive diversity concepts as part of the European IST (Information Society Technologies) METRA (Multi Element Transmit and Receive Antennas) project [3].