| Summary: | 碩士 === 國立交通大學 === 電信工程系所 === 95 === The use of particle filter on the channel equalization problem has been studied by many researches for years. As mentioned in [3], the weak light-of-sight (LOS) channel is one of the problems limiting the performance of the sequential importance-sampling (SIS) based equalization. In [3], the delayed-SIS (D-SIS) algorithm was proposed to solve this problem at the expense of high computation complexity. In this thesis we introduce a new class of blind SIS equalization algorithms for the frequency selective channels no matter how the first impulse of CIR (Channel Impulse Response) is.
We begin with a brief review of the particle filtering theory and establish the model of the particle filter equalizer. After the mathematical analysis of the BER in the particle filter based channel equalization systems, we can know how the performance of the SIS equalization algorithm is affected by the channel with an attenuated LOS. To overcome this problem and improve the performance, we use the idea of minimum-phase pre-filtering to maximize the LOS of the equivalent channel and propose the SIS decision feedback equalization algorithms. In the case when the channel state information (CSI) is known, this minimum- phase pre-filtering can be implemented with the decision feedback equalizers (DFE), whose coefficients are computed based on either the zero-forcing (ZF) or minimum mean square error (MMSE) criteria. In the case of unknown CSI and time-varying channel, the proposed adaptive blind SIS equalization algorithm pre-filters the receiver input by using the adaptive filters such as the least mean-square (LMS) or the recursive least squares (RLS). In both cases, we conduct the computer simulations to illustrate how the proposed SIS DFE algorithms improve the performance. We compare the performance of the D-SIS equalization and the proposed SIS decision feedback equalization and find that our approach outperforms the D-SIS on both the BER performance and the computation complexity.
Moreover, to save the computation of the adaptive SIS equalization algorithms, we propose a simplified scheme of the adaptive blind SIS DFE, named the Max-Weight blind SIS DFE algorithm We show that the proposed cost-effective algorithm can provide the performance almost the same as the original adaptive SIS DFE algorithm from the computer simulation results.
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