Broadband Wireless Communication Systems, Blind Equalization

Next generation wireless communication system imposes high standard for the data transportation rate and quality of service, which require new and more advanced physical layer technologies to support. Under the condition of high throughput rate, the frequency-selective property will severely degrade the signal quality in the receiver, causing unacceptable inter-code interference (ICI). For the sake of reducing or eradicating such negative influence and improving the system's performance, with high reliability and easy implementing structure, equalization technologies have been proposed and widely applied in the communication systems.The main work of this thesis is to research the channel equalization technologies. Firstly the technological improments of wireless communication are summarized and the new developmentments for next generation system are analyzed; then the equalization theories and algorithms are described; finally several computer simulation experiments are given to show the performance with necessary analysis and explanation. Besides these contributions, the new Turbo equalization algorithm and higher-order blind equalization algorithm are also specified and simulated, which have significant values in analysis and application. The most important creative job of this thesis is to present two novel blind equalization algorithms. By applying the new developments in signal processing field, our algorithms have outstanding performance with tiny additional computation complexity, which are verified by simulation experiments.The key work and innovations of this thesis mainly include:1. Research of the equalization theory and rules. Several experiments about the typical equalization algorithms are finished and summarized, including simulation of the new Turbo equalizer.2. Particular study of blind equalization algorithm. Computer experiments of the typical blind equalizers have been finished, such as the constant modulus algorithm (CMA) equalizer and higher-order equalizer.3. Proposed a new CMA equalization supported by adaptive convex combination theory. By utilizing the new developments of adaptive signal processing field, our new algorithm can get rid of the compromise in choosing different step-sizes, thus has faster convergence rate and better steady-state performance, which is confirmed by the simulation experiments.4. Presented a hybrid structure of MMSE blind equalization strategy. The optimization theory is introduced in this algorithm to combine the advantages of two different MMSE equalizers. As a result, our new algorithm has outstanding performance, which is verified by experiments in different circumstances.5. Implemented the new algorithms in the ADSP21160 based platform, which presents the implementing experience for application of these algorithms in commercial wireless telecommunication systems.