Subspace based estimation of the signal to interference ratio for TDMA cellular systems

The signal-to-interference ratio (SIR) has been highlighted in the literature to be a most efficient criterion for several methods aiming at reducing the effects of cochannel interference, e.g. diversity reception, dynamic channel allocation and power control. In this paper we address the problem on how to obtain fast and accurate measurements of this parameter in a practical context. We develop a general SIR estimation technique for narrow-band cellular systems, that is based on a signal subspace approach using the sample covariance matrix of the received signal. Simulation results for a GSM-like system show that the SIR can be estimated to within an error of 0.3 dB after only 200 ms, or within an error of 0.1 dB after only 0.6 seconds.