Summary
International Symposium on Antennas and Propagation
2010
Session Number:4FB1
Session:
Number:4FB1-4
Initial Weights for Improving Convergence Characteristics in Mobile Reception of the MMSE Adaptive Array for OFDM Transmission
Hitoshi Kojima, Nobuyoshi Kikuma, Hiroshi Hirayama, Kunio Sakakibara,
pp.-
Publication Date:2010/11/23
Online ISSN:2188-5079
Summary:
It is known that the OFDM (Orthogonal Frequency Division Multiplexing) transmission technology is used in the terrestrial digital TV broadcasting and wireless LAN. The OFDM is featuring high efficiency of frequency utilization and also effective use of FFT in the modulation scheme. In addition, a guard interval (GI) is inserted into the head of each OFDM symbol to overcome the delay spread of the channel. Hence, the communication performance of OFDM is superior to that of a single carrier in multipath environments where the delay times of multipath waves are within the GI length. On the other hand, inter-carrier interference is caused by incidence of multipath waves with delay times exceeding the GI length or by Doppler shift in the mobile reception environment, which results in serious degradation in the OFDM transmission performance. As one of techniques for suppressing the interference, the MMSE (Minimum Mean Square Error) adaptive array utilizing the GI in OFDM (GI-MMSE) was proposed which is a blind adaptive processor of pre-FFT type [2]. However, due to the blind processing, the improvement of the convergence characteristics of the adaptive system remains to be addressed [3]. In this paper, we consider the way of giving the initial weights to the GI-MMSE in the mobile reception for improving the convergence characteristics. Through computer simulation, we demonstrate how significantly convergence characteristics of the GI-MMSE adaptive array are improved by the proposed methods of making the initial weights.