LMMSE 등화기법을 적용한 DSRC 시스템 성능 분석

Abstract

The difference of the channel environment from former DSRC(Dedicated Short Range Communication) system and the next generation one comes from frequency selective fading channel environment, therefore ISI (Inter Symbol Interference) is occurred in wireless multi-path channel. The signal in wireless multi-path channel is affected by fading and ISI because of high data rate transmission, so the signal has the high error rate. The present modulation and demodulation method of DSRC system can not expect sufficient for providing data service over 1 Mbps, so the channel equalization and advanced modulation and demodulation methods are required.

OFDM (Orthogonal Frequency Division Multiplexing) is generally known as an effective technique for high data rate transmission system, since it can prevent ISI by inserting a guard interval. However, a guard interval longer than channel delay spread has to be used in each OFDM symbol period, thus resulting a considerable loss in the efficiency of channel utilization. Therefore the equalizer is necessary to cancel ISI to accommodate advanced ITS (Intelligent Transport System) service with higher bit rate and longer channel delay spread condition.

In this thesis, the channel equalizer for the OFDM？[DSRC system was designed and its performance in a multi-path fading environment was evaluated with computer simulation.

As a result, the performance of Pseudo LMMSE (Linear Minimum Mean Square Error) equalizer for the OFDM-DSRC has been improved comparing with LS (Least Square) equalizer at higher bit rate transmission system.