The Research And Implementation Of The Key Technology Of The LTE Downlink

The LTE (Long Term Evolution) scheme was proposed by3GPP, which is compatible with current3G telecommunications system. Channel estimation plays a quite important role in the LTE system which requires high data rate, high quality and high mobility. In addition to, Multiple-input multiple-output (MIMO) technology can breakthrough the constraint of limited Spectral efficiency and significantly increase the spectral efficiency of wireless systems. Hence, MIMO is also adopted by3GPP as an important method to enhance the overall transmission rate.The key technologies for LTE downlink are investigated in this thesis. Firstly, the basic knowledge of Physical Layer in LTE system is introduced. We mainly investigate LTE downlink pilot-based channel estimation algotithm,including the LS channel estimation algorithm, MMSE channel estimation algorithm, two-dimensional linear interpolation algorithm and the Gaussian interpolation algorithm. Considering the simulation conclusion and the complexity of hardware implementation, a scheme for designing the LTE downlink channel estimator is presented, which is implemented on DSP platform.Then the LTE downlink MIMO transmit diversity techniques and demultiplexing techniques are researched. We investigate the MRC receive diversity technique、SFTD transmit diversity technique and demultiplexing algorithms commonly used ML, MMSE, ZF algorithms, and then simulate them in the Matlab platform. According to the simulation result, a scheme for LTE MIMO transmit diversity and demultiplexing in downlink are put forward, which is also implemented on the DSP platform.