M Tech Dissertations

Permanent URI for this collectionhttp://ir.daiict.ac.in/handle/123456789/3

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Subject: search.filters.subject.Digital modulation

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    Frequency offset estimation in OFDM signals using particle filtering along with resampling methods
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2008) Jayanthi, V. Ravisankar; Vijaykumar, Chakka
    Frequency offset is one of the main effects the Bit Error Rate(BER) in orthogonal frequency division multiplexing (OFDM). There are many applications which depend on OFDM. The present method describes the estimation of frequency offset for OFDM irrespective of the distribution of the channel noise. This method uses Particle Filtering for the estimation of frequency offset. As Particle Filter is a non-linear and non-Gaussian estimator, there will be no constraint on the channel noise. This method also uses the resampling methods, which are essential in modifying the weight approximates during the iterations. Here the performance of the Particle Filter in estimating the frequency offset for the OFDM is observed along with the resampling methods.
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    ItemOpen Access
    Orthogonal frequency division multiplexing synchronization techniques
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2008) Ravikanth, Sivangi; Vijaykumar, Chakka
    Synchronization plays a major role in the design of a digital communication system. Essentially, this function aims at retrieving some reference parameters from the received signal that are necessary for reliable data detection. The OFDM is very sensitive to symbol timing and frequency offset. The loss of orthogonality among the subcarriers causes degradation of the OFDM system performance. so, the timing and frequency offset must be estimated and compensated before demodulating the OFDM signals. This report presents the study of different synchronization schemes for OFDM receiver. Different methods like Schmidl-Cox synchronizer, The Coulson synchronizer, The Minn-Zeng Bhargava synchronizer, Blind carrier offset estimation using unused subcarriers etc. Matlab experiments are conducted to study the performance of different synchronization schemes. The simulations results shows that Blind estimation method is more advantage over training symbol and Cyclic Prefix (CP) based methods in terms of Bandwidth saving.