Equalizing GMSK for high data rate wireless LANs

We simulate the performance of an equalized Gaussian minimum shift keying (GMSK) signal in an indoor radio environment with fading, noise, cochannel interference and intersymbol interference (ISI). We show that data rates of 20 Mbps at bit error rates (BER) ⩽10^-4 are possible with RMS delay spreads up to 25 ns using a simple limiter-discriminator-integrator receiver and a (6,4) decision feedback equalizer (DFE). In environments with larger RMS delay spreads, coherent detection is required for the same performance. We introduce a DFE structure which compensates for both modulator and channel ISI, and yet requires no power-intensive multiplication operations in the feedback section. An (8,8) DFE with 2-level switched (selection) diversity is shown to allow 20 Mbps data transfer at BER ⩽10^-4 for RMS delay spreads under 150 ns, with cochannel interference. Adding a (26,31) BCH code allows error-free reception of over 90% of packets with RMS delay spreads under 150 ns, and up to 70% of packets with RMS delays of 150 ns