Research On Channel Estimation Algorithm For SC-FDMA System In LTE Uplink

3GPP LTE is the evolution of the UMTS in response to ever-increasing demands for high quality multimedia services according to users’ expectations. LTE can provide high moving-speed、high bandwidth, reduce the delay, and reduce operating costs; Meanwhile, it achieves a packet core network based on all-IP, and who is able to support a variety of access technology. These advantages make this technology to be a research focus of B3G/4G mobile communications. In December2005, the3GPP determined to adopt OFDMA who is more mature in LTE downlink while adopt SC-FDMA whose PAPR is lower in LTE uplink. In recent years, SC-FDMA technology has much development with the researching of many experts and scholars, and it will be continue to improve at present. This dissertation investigates system transmission scheme and channel estimation algorithm of SC-FDMA in LTE uplink.LTE is simply introduced, the radio channel model is analyzed, the commonly used channel estimation algorithm based on pilot is introduced, the SC-FDMA system is analyzed, and the researching of SC-FDMA channel estimation algorithm by both at home and abroad is reviewed in this dissertation. Some creative works have been done as follow two aspects:1) An adaptive transmission scheme based on channel estimation of SC-FDMA system in LTE uplink is proposed. The scheme is acquired base on a comparison of the transmission performance between two subcarrier mapping methods of this system in different mobile environment. The adaptive transmission scheme according the movement speed of mobile terminal to choose corresponding way of subcarrier mapping, system adopt localized mapping in the high-speed environment while adopt distribute mapping in the low-speed environment. The result of computer simulation proves that the adaptive transmission scheme can improve the system’s communication performance by approximately2-4dB both in high-speed environment and in low-speed environment.2) A channel estimation algorithm of SC-FDMA based on reliable decision feedback symbols is proposed, too. This algorithm chooses the reliable symbols after initial channel estimation via setting threshold BER. These symbols are sent back to channel estimator as quasi-pilots together with original pilots in order to estimate again. The implementation steps of this algorithm are introduced, and the theoretical background and the error performance are analyzed in this dissertation. The result of computer simulation proves that this decision feedback algorithm can improve the estimation accuracy by1～2dB, meanwhile, it can improve the system’s communication performance by1～2dB.