The Signal Error Control Research And Design Using FPGA

With the technological development, the communication technology has gained more and more attentions by the governments in different countries. However, the primary purpose of communication system is information accuracy. Xiang Nong pointed out that this encoding way is called Channel Coding(also called Error Correcting Code), which can promote the reliability of channel transmission after encoding the original information. That is to say, nowadays the development of channel transmission is based on Xiang Nong Channel Coding Theorem and tends to be more and more mature. In 1993, two French professors Berrou and Glavieux, with their Burmese doctor Thitimajshima, came up with the new ways of encoding Turbo Codes, published on Near Shannon limit error-correcting coding and decoding: Turbo codes in ICC conference. It skillfully used two simple component codes, parallelly intertwined together by the pseudo-random interleaver, to construct a long code with the pseudo-random characteristics. And the pseudo-random decoding was accomplished through the multiple iterations of the two soft-in/soft-out(SISO) decoder. When the simulation results came out, its performance was much better than the other way of coding. Therefore, Turbo made great influences in this industry.This thesis is mainly about the coding and decoding of the data transmissions after the system processing. We will apply Turbo coding scheme and the codes before transmission are required in the data. There are many methods to realize the decoding, such as by IP Core and hardware description language, in which all the means are involved in this system. If combined the two together, it will give full display of the potential of FPGA.Since most of the technologies in Turbo Coding are combinations of other coding technologies and mature, this thesis will firstly introduce the present frequently used coding technologies, especially about linear block codes as other coding technologies are mostly a subset of it. On this basis, comes Turbo Coding. There was only one coding structure, Parallel Cascade Convolution Code(called PCCC), when Turbo Coding was firstly put forward. In order to simplify the system, we will apply the initial coding structure. However, the author will only introduce the structure, but not its algorithm and the way of derivation, since we will apply the free IP Core to realize the decoding.This essay will mainly focus on the code method of Parallel Cascade Convolution Code(PCCC) and introduce specifically every small module in the structure, especially interleaver. The author will not only make explanations about the design, but also the Turbo Code influence after Matlab simulations under the means of Verilog. Convolutional code is mainly adopted and we will explain its encoding means and derivation formula in detail.Verilog coding is mainly applied in Turbo with the help of IP Core. This essay lists part of key signal timing, and the whole system can work in an orderly way under the control of the key signals. This is the first edition, which mainly realizes its function so there is no deleting tool and IP Core can be used directly when decoding. In terms of the FPGA configuration, we will use the active synchronous serial data bus(SPI) to solidify the program, which will be put in the flash. The program can be kept permanent and there is no loss after power off, with JTAG adjustment method used.In system functional testing, we first apply MATLAB to stimulate the whole system, and compare the number of the error codes between 1000 characters and 1500 characters under the same situation. Then in the piratical running system process, we will run many a data in a row and test the sent data with oscilloscope. Through the complete analysis and test, it is proved that this system fully displays its function and it is the most ideal method to use Turbo codes to code and decode with FPGA.So far, most researches about Turbo codes are restricted by the low rate of binary coding while Turbo code is far more than this. As a matter of fact, it can be combined with TCM and multi-band coding techniques, etc., which are applied in the high efficient modulation and transmission and also have the similar functions with channel capacity. All in all,It is because of the superior function of Turbo code that global researchers devotes themselves to putting it into use, not only in the field of mobile satellite communication system, also in digital audio and video broadcast, deep space communications, deep space network, UMTS/3 GPP, CDMA system, etc..