Short-term Burst Signal Blind Study

In uncooperative communication, the blind processing of short burst signals is an important technology problem. In order to do systematic theory analysis for the technology of short burst signals' blind procession and solve the problems encountered in practice, the writer analyzes for several important parts of short burst signals' blind demodulation detailedly and provides some processing algorithms to solve the corresponding problems. Most content of this dissertation is proved by practical application. In the first chapter, the conceptions of short burst signals and blind procession are explained firstly, and then main contents of this dissertation are introduced in brief.The second chapter studies the carrier synchronization for short burst signals firstly. The writer considers that comparing to the loop way, the way of forward estimation is more suited to the blind processing of short burst signals. So, the forward estimation technology of carrier frequency and phase is investigated in this chapter. In the investigation of carrier frequency, the writer presents that the method of frequency estimation for fading channel should be "the blind equalization that independent of carrier error + the frequency estimation algorithm of unfading channel" by analyzing of various algorithms for various channel. An iterative approach method for parameters estimation base on "rough estimation + iterative dichotomous fine search" is summarized. The factors that impact the range of frequency estimation are analyzed and a way to extend the range based on multi-sampling is provided. Almost all presented carrier phase acquisition algorithms have a comparative low performance, which will lead to degraded performance of demodulation. Therefore, the writer provides two methods to improve the performance of carrier phase acquisition: (a) an algorithm of ML iterative approach; (b) the acquisition algorithms combining tracking algorithm (DD algorithm). The two methods both can enhance the acquisition performance; accordingly the demodulation performance in the beginning is enhanced. Secondly, the timing synchronization is studied. According to the speciality of insensitive to timing error for fractionally spaced equalization, the writer makes a study that timing synchronization and channel equalization are both achieved by using fractionally spaced equalization. But for the impaction of timing frequency error, some means must be adopted to compensate the timing frequency error. So, the way of shifting equalizer taps' coefficients to compensate the timing frequency error is given and two methods to decide the time of shifting are provided: (a) the way of combining forward timing error estimation; (b) the way of correlation.The third chapter indicates that the "data reuse" Bussgang class blind equalization algorithm is an applied method to solve the problem of short burst signals' equalization by analyzing all kinds of equalization algorithms. So, the way of data reuse processing is summarized and analyzed. It can be confirmed by others' presented results and our simulation that the "data reuse" can accelerate convergence rate and yet raise the steady error. The representative algorithms are BNDR-LMS and affine projection algorithm. In order to improve the convergence performance of constant modulus algorithm (CMA), the writer introduces the data reuse to CMA to accelerate the convergence rate and use set-member filter to reduce the steady error. Then, a new constant modulus algorithm named set-member bi-normalized data reuse constant modulus algorithm is presented.