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|Title:||PILOT ASSISTED CHANNEL ESTIMATION AND EQUALIZATION OF DOUBLY SELECTIVE FADING CHANNEL|
|Authors:||Sharma, Pradeep Kumar|
|Keywords:||FADING CHANNEL;OFDM;CHANNEL ESTIMATION;ELECTRONICS AND COMPUTER ENGINEERING|
|Abstract:||Reliable and fast transmission of information over rapidly varying wireless channel is essential for next generation wireless broadband systems. Orthogonal Frequency Division Multiplexing (OFDM) is one of the efficient techniques to provide high data rate transmission over fading dispersive wireless channel. However, when the intervening wireless channel is doubly selective, the transmitted signal undergoes impairments due to the multipath and Doppler spread. In order to perform coherent detection and to suppress the effect of ICI, receiver has to employ efficient channel estimation and equalization schemes. In this dissertation, we address the problems of wireless channel estimation and equalization for OFDM transmission system over doubly selective fading channel. Relying on complex exponential basis expansion model (CE-BEM), which allows the modeling of each time varying channel tap as a linear combination of complex exponential basis function along with the time invariant BEM coefficients to model doubly selective fading channel, pilot assisted channel estimation for OFDM system is devised. The performance of channel estimation algorithm is further improved by oversampling the Doppler spectrum or also called generalized complex exponential (GCE) BEM, which reduces the frequency spacing of complex exponential and gives a better representation of underlying doubly selective fading channel. Receiver equalization in doubly selective fading environment, in presence of ICI, is one of the challenging tasks. In high mobility OFDM systems, the conventional MMSE block linear equalizer is incapable of removing residual ICI because of its high computational complexity. We address the problem of equalization in high mobility OFDM systems by formulating a state-space model of underlying system. Kalman filter is employed as an equalizer to estimate the unknown state of the system, which comprise the transmitted symbols.|
|Research Supervisor/ Guide:||Mehra, D. K.|
|Appears in Collections:||MASTERS' DISSERTATIONS (E & C)|
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