Akademik Veri Yönetim Sistemi
Proceedings - 2001 International Conference on Third Generation Wireless and Beyond, San Francisco, CA, Amerika Birleşik Devletleri, 30 Haziran - 02 Temmuz 2001, ss.999-1004
RAKE receivers suffer degradation in performance under fast fading due to errors in channel state estimation. The wide-sense stationary uncorrelated scatterer, channel model lends itself to time-frequency canonical representation, and provides additional diversity in the frequency axis. Using the joint multipath-Doppler diversity model based on this canonical representation, we introduced in [4, 5] nonlinear time-frequency decision-driven multiuser detectors employing interference suppression. Examining these time-frequency multiuser detectors, it can be seen that there are two key operations performed: MAI suppression and time-frequency diversity combining, therefore depending on the order in which operations are performed, there are two possible receiver structures: pre-combiner canceller (diversity combining followed by MAI cancellation) and post-combiner canceller. (MAI cancellation followed by diversity combining). In this paper, we analyze and compare pre-combining and post-combining interference suppression in time-frequency decision-driven multiuser detectors to reveal the tradeoffs in their implementation. Simulation results based on realistic fast-fading assumptions demonstrate that the postcombining scheme has a better bit-error-rate performance compared to pre-combining and the performance gap increases with the number of independent diversity channels, however precombining has lower computational complexity than postcombining.