The Technology Research On Channel Estimation Of Long Term Evolution Uplink

3GPP LTE (Long Term Evolution) is the third generation mobile communication technology in the long-term evolution of the project, it has changed and enhanced the 3G technology, while using orthogonal frequency division multiplexing (OFDM) as the evolution of its wireless network standards, it can not only flexibility support multiple transmission bandwidth, improves the peak rate of uplink and downlink transmission systems greatly, but also improves the user's performance in the edge of the cells, increases cell capacity and reduces the system delay. However, because the transmitted signal has higher PAPR in the OFDM technology, it reduces the efficiency of the transmitter's power, and it can become to be detrimental to their implementation in the uplink. In order to achieve a lower peak power to reduce the loss of the transmitter in the LTE uplink, we choose single carrier frequency division multiplexing (SC-FDMA) for uplink transmission scheme. SC-FDMA technology can not only be effective against the channel frequency selective fading in the transmission system, it also can obtain lower PAPR performance.In this paper, we mainly focus on the channel estimation technology research which is based on LTE system, and we can fully understand the basis of relevant protocols, according to the characteristics of the uplink with the existing channel estimation techniques, and to design the feasible channel estimation scheme to accord with the LTE uplink scenarios.Chapter 1 mainly presents a brief review of the background, the requirements and the key technology in the LTE system; it also analyzes the development of status and the common channel estimation method in the uplink system.Chapter 2 investigates the type of frame structure, the design of the parameters and the SC-FDMA'S framework in LTE uplink transmission system. We compare the SC-FDMA transmission mode interleaving time domain frequency-division multiplexing (IFDMA) technology in the time domain with the discrete Fourier transform orthogonal frequency division multiplexing multiple access (DFT-S-OFDM) technology in the frequency domain; we also analyze about the PAPR performance in the different subcarrier mapping modes in time-domain processing of the intervolved frequency-division multiplexing (IFDMA) technology and the central frequency division multiplexing (LFDMA) of the SC-FDMA system in LTE uplink. We also compare the peak performance with OFDMA techniques in the downlink, the simulation results show that because of different sub-carrier mapping modes, there are great different PAPR performance in LFDMA and IFDMA. At the same time, compared to OFDMA technology, SC-FDMA technology is lower about the peak performance. This illustrates the reason why we use SC-FDMA technical in LTE uplink. Chapter 3 derives the different pilot modes in wireless communication systems; the pilot signal design in LTE uplink transmission process, it also introduces commonly estimation about the minimum mean square error (MMSE) channel estimation and least squares(LS) channel estimation. Simulation results show that under different modulations and rates of the mobile station, because of the different Doppler shift, it can cause different effects in the performance of channel estimation, but in general, the MMSE channel estimation has better bit error rate (BER) performance than the LS channel estimation. At the same time, even the same channel estimation mode (either MMSE or LS) and the same SNR, the higher the Doppler frequency shift will cause poorer performance in the mean square error (MSE), and that is, the MSE performance of the system increases as the Doppler shift decreases. Finally, the improved pilot signal channel estimation in the frequency domain: FDLS, FDLMMSE and FDLS/CWD are analyzed; simulation results show that the LS channel estimation method based on window functions has better channel estimation performance.Chapter 4 presents the exact channel estimation error on BER performance, while the channel estimation error is derived on the system bit error rate formula. The formula derived theoretical analysis shows that under different modulation methods, channel estimation error on system bit error rate formulas vary greatly, and the BER performance depends not only on the modulations of channel estimation methods but also relates the pilot signal in the systems.Finally, conclusions and future work are summarized in chapter 5.