Research On Channel Estimation And Equalization Algorithm Of Single Carrier Frequency Domain Equalization

Single carrier frequency domain equalization (SC-FDE) is an effectiveanti-multipath technique, it offers similar signal processing, similar performance andcomplexity to orthogonal frequency division multiplexing (OFDM) avoiding the highPeak to Average Power Ratio (PAPR), the high sensitivity to carrier frequency offsetand phase noise. Therefore single carrier frequency domain equalization is becomingattractive in recent years, and has been adopted by the IEEE802.16a standard asphysical layer transmission technology. This paper investigate SC-FDE technology,focusing on channel estimation and equalization algorithm, completing the followingmajor research:Firstly an improved frame structure of SC-FDE system is proposed byinvestigating the frame structure of SC-FDE and the channel estimation for using timedomain multiplexed pilots, the scheme can solve the problem of increasing the systemoverhead, which is caused by improving system performance. The proposed framestructure divides the Unique Word (UW) of the traditional frame into several of thesub-UW and the data maintain constant, Thus The channel estimation is accomplishedby the several sub-UW. Therefore the accuracy of channel estimation can be improvedefficiently by taking the average value of several channel estimations, finallyimproving system performance. The improved frame of SC-FDE system is superior tothe traditional frame of SC-FDE system in performance of Bit Error Ratio (BER),meanwhile without increasing the system overhead.Secondly discrete cosine transform (DCT)-based noise suppression Least Square(LS) channel estimation is proposed for SC-FDE system to mitigate the effect of noise,Which is caused by traditional Least Square channel estimation. The energy of thechannel frequency response is gathered in the low frequency by DCT, the power in thehigh frequency region can be regarded as noise, reducing the noise on the impact ofLS channel estimation by setting the value of high frequency to zero, ultimatelyimproving system performance. Compare with traditional LS channel estimation,DCT-based LS channel estimation significantly improves the performance with acomparable complexity.Finally an improved iterative frequency domain decision feedback equalizationalgorithm is proposed for SC-FDE system to solve the problem of decision error probability, which is not reasonable seted in the low complexity iterative blockdecision feedback equalization algorithm. The system performance will be improvedby setting a reasonable decision error probability in the iteration. Compare with lowcomplexity iterative block decision feedback equalization algorithm, the proposedimproved algorithm improves the performance with a lower complexity.