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Title of Thesis

Aqdas Naveed Malik
Institute/University/Department Details
Muhammad Ali Jinnah University/Department of Electronics Engineering
Electronics Engineering
Number of Pages
Keywords (Extracted from title, table of contents and abstract of thesis)
blind channel equalization, singal processing, second order statistics (sos), higher order statistics (hos), 4-qam

In this dissertation we have given some new algorithms for blind equalization. In case of the equalization based on second order statistics (SOS), a sufficient condition for blind equalization is given and proved when the source symbols are colored. Based on the given condition a new algorithm for coloured sources has been derived. The performance of the new algorithm as given by simulations is comparatively better than the previous works, especially at low signal to noise ratios. Then a new energy matching technique in SOS domain is introduced. It is very simple and complete and computationally light scheme, which provides faster convergence. This scheme is valid only for equal energy source symbols. It outperforms the existing techniques of same category in simulations

The work is then carried out for the domain of higher order statistics (HOS). In order to take advantage of both the SOS and HOS based techniques the hybrid approach of HOS-SOS is developed. The cost function of HOS based algorithms is modified by imposing the conditions based on SOS which resulted into another new algorithm for binary source symbols. The algorithm given excellent results and converges in three to five epochs only. This work is then further extended to cut down the computational complexity. Some over-stressing conditions with little contribution to the performance but possessing higher level of complexity have been removed. Energy constraint as given in SOS domain is also applied in the hybrid domain. Further modification is done to deal with complex source symbols e.g. 4-QAM. All this resulted in a much faster algorithm which converges in one epoch only. Simulation results of each algorithm demonstrate the validity and superior performance of the new algorithms over the previous works. Some concluding remarks and future directions in this field have been proposed at the end.

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696.05 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
112.88 KB
2 1 Introduction 1
99.15 KB
  1.1 Introduction 1
  1.2 Hos Based Approaches 3
  1.3 Sos Based Approaches 5
  1.4 Contributions Of The Dissertation 9
  1.5 Organization Of The Dissertation 11
3 2 Mathematical Formulation Of Implicit Hos And Sos Based Algorithms 13
98.7 KB
  2.1 Implicit Hos Based Algorithms 13
  2.2 Sos Based Algorithm 20
  2.3 Removal Of Heme 18
4 3 Blind Equalization Of Channel Using Sos With Coloured Sources 27
171.93 KB
  3.1 Theoretical Farmework 28
  3.2 Phase Ambiguity In Equalized Symbols For Real Channel 35
  3.3 Simulations And Results 36
  3.4 Energy Matching Approach For Blind Equalization Of Channels With Equal Energy Sources 43
5 4 Hybrid Hos-Sos Approach For Blind Equalization Of Channels 50
147.34 KB
  4.1 Introduction 50
  4.2 New Proposal 51
  4.3 Simulations Results For Binary Case 57
  4.4 Extension To Complex Coloured 4-QAM And The Use Of Energy Matching Term 62
6 5 Conclusions 70
29.93 KB
  5.1 Conclusions 70
  5.2 Future Work 72
7 6 Refernces 74
174.79 KB
  6.1 Appendix-A Proof Of Theorem 89
  6.2 Appendix-B,C, 91-94