Channel Equalization in HSDPA Receivers: Trade-Off between Performance and Complexity with a variable Oversampling

M. Schämann, M. Bücker, Sebastian Hessel, Ulrich Langmann

VTC 2006 Spring, Melbourne, Australia, May 2006


In this paper algorithms for HSDPA receivers are investigated and optimized to achieve the specified performance while obtaining a low energy consumption. Different approaches including standard Rake combiner, MMSE and Prefilter-Rake equalizers in combination with a variable oversampling ratio are discussed. The Bit Error Rate (BER) is simulated within a complete fixed point physical layer model and the complexity of the different algorithms is compared. All equalizers fulfill the requirements of the specifications even for a vehicular propagation channel with a receiver velocity of 30 km/h. The Prefilter-Rake equalizer using the Levinson algorithm reaches a throughput of 1.5 Mbit/s for SNR values greater than 6.1 dB. The comparison of performance and complexity demonstrates that the oversampling ratio can be tuned down to 2 samples per chip depending on the environment to reduce the complexity and energy consumption while maintaining the demanded performance.