Study on Transmission Rate Optimization by Switching Between Diversity and Multiplexing in 4G LTE MIMO system

• Main Author: 蘇浩平
• Other Authors: 林昭志
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/89447554688836227459

碩士 === 國立彰化師範大學 === 電機工程學系 === 103 === In recent years, applying the MIMO (Multi-In Multi-Out) and OFDM (Orthogonal Frequency-Division Multiplexing) technologies applied in 4G LTE system makes the transmission rate higher than the previous wireless mobile system. In this thesis, we focus on the transmission rate and error rate of different transmission methods under different environments, and propose a new algorithm which switches between the transmission method to fit different environments, and achieve higher transmission rate and less retransmission. By considering different environments and different modulation, we discover that the BER performance of multiplexing is worse than STBC (Space Time Block Code) in Rician channels, and also the BER will get even worse when the k factor of Rician channel becomes bigger. Therefore, we propose a method by observing the variance of channels to determine the type of channels. We found that the STBC can be applied in a low SNR (signal to noise ratio) environment, and the multiplexing can be applied in a high SNR environment to reach high transmission rate. The purposed algorithm in this thesis can automatically switch between STBC and multiplexing by different channel types and SNR values to reach higher transmission rate.