Multi-user detection applied to GSM communications

In this paper we propose to apply to the GSM system multi-user detection (MUD) techniques generally used in CDMA networks. The constraint of using the GSM wave form makes it impractical to use the optimum receiver due to its high complexity. Thus, in this paper, we derive the multi-user sub-optimum DFE-MMSE adapted to the GSM wave form. It relies on a linear approximation of the GSM modulation leading to a staggered modulation and thus requires a specific, (and multi-user in our case) equalizer to achieve good performances (Tu 1993). Not taking into account the fact that the modulation is staggered (as in Tripathi et al. 2000) leads to poor performances. The symbol detection is made possible by means of multiple antennas at the receiver. This technique is actually being tested on real data for underground transmissions in an IST funded project called ESCORT.