Enhanced Space-time Capture Processing for Random Access Channels

The problem maximizing the throughput in a Random Access Channel (RACH) in a TDMA-based system is addressed. A general analysis of a Slotted ALOPHA (S-ALPHA) system is presented which shows that the possibility to recover more than one user in a RACH collision can significantly improve the system performance. Three capture algorithms based on semi-blind space-time filtering are proposed. Their effectiveness compared to the conventional (power) training-based capture algorithm, is demonstrated by means of simulations in a GSM (EDGE) system. The best results are obtained for a multistage version of the training-like algorithm, based ont he Least Squares (LS) estimation of space-time filter coefficients.