在高速鐵路環境下正交分頻多工系統使用線性通道估測及通道估測更新技術之比較與改進

Abstract

本研究的目的在於探討“在高速鐵路環境下，提供正交分頻多工無線通訊系統有效的通道估測方式”。在高速移動環境下，由於無線通道中多重路徑干擾及都卜勒效應所產生的種種現象，使得無線通訊信號會遇到許多干擾，造成傳輸困難。雖然有直視波的存在，且郊區之延遲路徑較少可簡化問題，但

This paper focuses on “effective channel estimations for OFDM wireless communication system in high speed train environment.” Because of multi-path interference and Doppler effect, wireless communication signals are interfered and hard to be transmitted. Although there are the existence of line of sight and fewer delay paths in high speed train environment to improve the situation, we still have to use more known signals to estimate the channel state correctly, which will lower the transmission efficiency. In this paper, we will discuss some methods to improve this situation. We first use traditional linear channel estimation to figure out how many known signals are in use, and how much space do we need to set for the pilots in high mobility environment. Then, we use the method of updating channel state information to achieve lower bit error rate and higher transmission efficiency in high mobility environment. In order to improve the transmission efficiency, we also try many kinds of methods to solve the problems under different situations to achieve our goal. Finally, we compare each method of channel estimation by simulation, and we propose some ways that we can further improve the system in the future.