LMMSE Channel Estimation for IEEE 802.16e and 802.16m OFDMA Downlink

• Main Authors: Wang, Chih-Wei, 王志偉
• Other Authors: Lin, David
• Format: Others
• Language: en_US
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/39985531924885606593

碩士 === 國立交通大學 === 電子工程系所 === 98 === OFDMA (orthogonal frequency division multiple access) technique has drawn much interest recently in the mobile transmission environment and been successfully applied to a wide variety of digital communications applications over the past several years. One of the main reason to use OFDMA is its robustness against frequency selective fading and narrowband interference. We focus on the OFDMA downlink channel estimation based on IEEE 802.16e and 802.16m. We present two channel estimation methods. One is advanced 4-point linear interpolation. First, we use LS estimator on pilot subcarriers because of its low computational complexity. Second, we estimate the channel response in the middle of the pilot location in the time domain. Finally we estimate the channel response on data subcarriers using linear interpolation in the frequency domain. The other method is LMMSE channel estimation, First, we use LS estimator on pilot subcarriers, and do linear interpolation at the pilot location in time. Second, we estimate the delay parameters. Third, we find the autocorrelation function associated with the approximate PDP. Finally base on this autocorrelation function, do LMMSE filtering to estimate the data subcarrier response. We verify our simulation model on AWGN channel and then do the simulation on multipath channels for IEEE 802.16e and 802.16m. In this thesis, we first introduce the standard of the IEEE 802.16e and 802.16m OFDMA downlink. Then we describe the channel estimation methods we use and discuss the performance in each transmission condition for IEEE 802.16e and 802.16m.