Design And Implementation Of Wireless Transmission Uplink In LTE-A System

The formal commercialization of LTE-A marks that the commercial value of LTE-A system began to spring up. This thesis mainly focuses on the design and implementation process of LTE-A uplink wireless transmission.Firstly, according to the LTE-A physical layer protocol, this thesis introduced the basic knowledge about LTE-A system, which covers frame structure and resource block. At the same time, it also describes the founding process of physical uplink channel in detail.Secondly, the transmitting and receiving technique for the PRACH baseband signal is studied. Direct sequence transmitter and fully frequency domain receiver are discussed in the first. In order to reduce the complexity, at the transmitter, the DFT operation was simplified by considering the characteristic of ZC sequence. According to the DFT pounding theory, the large-scale IDFT operation can be replaced by several small-scale IFFT operations, and that reduced the computational complexity. At the receiver, the DFT operation was performed after down-sampling, and the anti-alising fliter was added to avoid the spectrum alising effects. The simulation results showed that the improved scheme has lower complexity and no performance loss. Finally, the implementation of the PRACH module is also given.Thirdly, a patially symmetric extending DFT based channel estimation scheme is proposed. This scheme is performed by partially and symmetrically extending the initial LS estimation and then applying a MMSE filter in the DFT domain. Simulation results show that the proposed channel estimator can effectively improve the estimation performance with only a few extended points, and the computational complexity is comparable with the traditional DFT-based method.Finally, this thesis study a whiten filter based solf-demodulator. This demodulator divides all user’s subcarrier symbols into several groups, and each group has two or three symbols. When detecting a certain group of symbols, the other symbols are treated as interference, which would be whitened together with noise. The simulation results indicate that this demodulator can achieve a good compromise between complexity and performance.