The Research And Implementation Of Channel Estimation In Wireless Telecommunication System

With the development of the mobile telecommunication implementation, it is required that the telecommunication systems supply better communication service quality to more customers even in complicated environment. The communication technology development is highly required. Orthogonal frequency division multiplexing modulation technology, which effectively resists multi-path fading interference and being with high spectrum efficiency, perfectly satisfy the requirement of the telecommunication development. The coherent demodulation is used in the OFDM system and in this case the channel information is needed so the channel estimation technique is of great significance.The channel estimation schemes are studied. The channel estimation schemes for OFDM based system are introduced in detail. Channel estimation technique for OFDM based systems can be grouped into two main categories: blind and non-blind. The non-blind channel estimation with aided data is studied. The basic principles of the aided data location are introduced, and three kinds of channel estimation schemes, the Least Squares (LS) channel estimation technology, transform domain technology and Linear Minimum Mean Square Error (LMMSE) channel estimation technology, are described.From the point of view of practical implementation, the simulation of LS technology, transform channel estimation and linear interpolation technology are based on WiMAX and LTE single-input single-output systems. In the WiMAX downlink system the comparison of effect of the two kinds of aided data is simulated, and the weight factor's effect on the system performance is analysed. In the LTE downlink system the effect of the transform estimation with the LS estimation scheme to the system performance compaired with the linear interpolation with LS scheme is simulated and analysed. In the LTE uplink system the resistance of the LS estimation scheme against moving speed is simulated. And the performance difference of the LTE uplink and downlink system respectively with LS estimation scheme and ideal estimation scheme is analyzed both in simulation result and in theory. In the end a kind of aided data value is proved theoretically which can supply the best condition for channel estimation.