Fine timing synchronization based on modified expectation maximization clustering algorithm for OFDM systems

A novel fine timing synchronization method based on the modified expectation-maximization (EM) clustering algorithm is proposed for orthogonal frequency-division multiplexing systems. Using the cross-correlation metrics of one preamble symbol, the cross-correlation peaks corresponding to the channel arriving paths are identified by the proposed modified EM clustering algorithm, the position of the first coherent cross-correlation peak is then chosen as the start of the frame. Computer simulations show that the proposed method is robust in multipath dispersive channels and achieves superior performance to existing techniques in terms of timing accuracy

Channel Estimation And Correction Methods For Ofdma Based Lte Downlink System

In present era, cellular communication plays a vital role for communicating over long distance. The number of mobile subscribers is increasing tremendously day by day. 3GPP LTE is the evolution of the UMTS in response to ever-increasing demands for high quality multimedia services according to users\u27 expectations. The average data consumption exceeds hundreds of Megabytes per subscriber per month. To introduce, summarize and get acquainted with this new technology LTE is one of the main objectives of my thesis. The Downlink is always considered an important factor in terms of coverage and capacity aspects in between Downlink and Uplink factors for cellular communication. Orthogonal Frequency Division Multiple Access (OFDMA) and Multiple Input Multiple Output (MIMO) are the new technologies which enhance the performance of the traditional wireless communication experience for downlink. In this thesis, we considered the downlink system for channel estimation by using different algorithms and interpolation methods. Channel Estimation algorithms such as Least Squares Estimation (LSE) and Minimum Mean Square Error (MMSE) have been evaluated for different channel models. The interpolation method used in algorithms is Linear, Piecewise constant, Averaged and Pilot averaged. I measured the performance of these algorithms in terms of Bit Error Rate (BER) and Symbol Error Rate (SER). The results are presented to illustrate the salient concept of the LTE communication system