Efficient Blind Detection for OFDM System in Selective Fading Channels

摘要

Pilot-assisted channel estimation is frequently used for the orthogonal frequency-division multiplexing (OFDM) system On the other hand one can apply blind detection to enhance the throughput of communications However not all blind algorithms can be applied in time-varying or frequency-selective fading channels Furthermore blind algorithms usually have higher complexity In this thesis we first propose a general principle by which one can build a metric for blind detection from any pilot-assisted channel response (CR) estimation algorithm By this principle and based on the least-squares-fitting (LSF) pilot-assisted CR estimation we derive a metric for blind detection and propose an efficient blind data detection algorithm The proposed algorithm is operated on a block of received symbols that are along subchannels or along time slots and therefore the proposed blind detection can be applied in frequency-selective or time-varying fading channels With the proposed tree search method the proposed algorithm attains the same error performance as a previous blind detection algorithm based on the same metric while the complexity is greatly reduced We further apply the channel prediction to obtain a better initial block in the tree search such that the complexity can be further reduced A range-reduced scheme is also proposed to give a trade-off between performance and complexity In the fast time-varying channel we can combine the proposed blind detection with an inter-subchannel interference (ICI) self-reduction algorithm to reduce the effect of ICI keywords: OFDM blind detection inter-subchannel interference

獎項日期	2015 1月 15
原文	English
監督員	Ming-Xian Chang (Supervisor)