Fast Fading Channel Estimation for OFDM Systems with Complexity Reduction

Abstract

Channel estimation plays a significant role in the Inter‐carrier interference (ISI) mitigation and symbol detection in Orthogonal frequency division multiplexing (OFDM) systems. As the speed of mobile terminal increases, the channel changes rapidly, causing fast fading which will degrade the system performance. In this paper, a low complexity fast fading channel estimation method suited for scattered pilot OFDM systems is proposed. This method is characterized by estimating channel matrix directly in the frequency domain, which can significantly reduce the channel estimation complexity with good system performance. Simulation results verify its superiority over the existing estimation methods.

A Double-Threshold Channel Estimation Method Based on Adaptive Frame Statistics

“…The pilot-based channel estimation methods are often preferred due to their reliability and simplicity. Usually, the pilots are inserted in block-type [7], comb-type [8], or scatter-type arrangements [9]. In the block-type arrangement, the pilots appear in a few OFDM symbols of all subcarriers.…”

Channel estimation based on superimposed pilot and weighted averaging

“…Gong et al 9 considered the time-varying characteristics of different symbols and adopted a new interpolation method to introduce generalized spatial modulation-OFDM technology into the high-speed railway wireless communication system. In pilot-based channel estimation, it can be divided into comb pilot 10 , block pilot 9 , and scattered pilot 11 according to the way of pilot insertion. Although the channel can be easily estimated by inserting pilot sequences into the transmitted data, it will lead to undesirable loss of data-rate and reduce spectrum efficiency 12 .…”

“…Superimposed pilot (SP) 13 is based on other types of pilot 9 – 11 , and the data symbols are superimposed with pilot symbols, which can avoid the reduction of spectral efficiency and data rate. Moreover, compared with the conventional pilot scheme, it increases the available bandwidth 14 .…”