MMSE equalization for UMTS HSDPA

The impact of 'advanced' mobile receivers incorporating dual-port antenna diversity and chip-rate equalization is assessed in terms of UMTS Release-5 high speed downlink packet access (HSDPA) link and system throughput. The addition of a second antenna port to the RAKE receiver increased the link-level throughput under 3GPP RAN WG4 test conditions by 25-100%, while a chip-rate minimum mean square error (MMSE) equalizer increased throughput by approximately the same amount for the time-dispersive (Pedestrian-B) channel. Assuming ideal channel estimation, the improvement in sector throughput was between 25-90% depending on the receiver configuration. Neglecting TCP, user throughput increased 50 to 100% when either receives diversity or MMSE equalization was applied, with the throughput increase becoming 100 to 200% for the dual-port MMSE case. When TCP was included, however, user throughput improvement reduced to 20% (MMSE equalizer), 33% (dual-port RAKE) and 45% (dual-port MMSE) respectively for the same system load.