24 GHz MIMO Channel Measurements for Indoor Environments


Multiple antennas at transmitter and receiver introduce spatial degrees of freedom into a wireless communication system. Space-time signal processing utilizes these degrees of freedom to boost link capacity and/or to enhance link reliability of multiple-input multiple-output (MIMO) communication systems. With spatial multiplexing one can increase the data rate without additional cost of bandwidth or power by transmitting data streams simultaneously over spatial sub-channels which are available in a rich scattering environment.

It is expected that future wireless broadband communication systems will operate beyond 5 GHz. Examples are wireless local area networks (WLANs) operating in license-free frequency bands at 17 GHz (Hiperlan) or at 24/60 GHz (ISM bands). In higher frequency bands it is possible to accommodate a larger number of antennas in a given volume (rich array) because the array size scales down with increasing frequency.

For zero-mean i.i.d. Gaussian channel coefficients the ergodic capacity of a MIMO channel with M transmit and N receive antennas scales linearly with min{M,N} compared to a corresponding single-input single-output (SISO) channel. However, there is a major obstacle in the practical exploitation of MIMO technology: the capacity gain depends strongly on the propagation environment and diminishes with increasing correlation of the channel coefficients. In higher frequency bands we expect an increase in correlation because the propagation channel becomes more and more line-of-sight (LOS) and we are confronted with a rich array -- poor scattering regime.

In this project you will perform virtual MIMO channel measurements at 24 GHz with our ECHO24 measurement system. From the measurements you will evaluate important channel parameters such as angular spread, condition number and rank of the channel matrices. The goal is to quantify the multiplexing cabability of indoor MIMO channels at 24 GHz.

Subject area MIMO channel measurements, MIMO communications, MIMO channel models
Type of work 50% measurements, 30% Matlab, 20% theory
Supervisor Dr. Boris Rankov
Professor Prof. Dr. Armin Wittneben