Research On Fire Code Decoding Algorithm And Its Application On GSM

Fire code is a kind of cyclic code, which is used to detect and correct burst errors. For this kind of error-correcting code, it is easy to design different code according to different requirements, and the decoding is very simple, so it is widely used to correct burst errors in computer systems and communication systems, such as error-correcting of disk and error control system in GSM. Fire code often used as outer channel coding, combined with the convolution code as inner cods, can effectively capture and correct the ganged error missed out.A Fire code has a generator polynomials of the form g(x)=p(x)(xc-1), where p(x) is an irreducible polynomials of degree m and periode defined on GF(2), c and e are relatively prime. The number of the codeword bits n is equal to the least common multiple of c and e, that's to say n=LCM(c, e), the number of supervision bits is r=m+c, and the number of information bits is k=n-m-c.The traditional decoding method can use fire code to correct a burst error with a length of not more than b,and detect a burst error with a length of not more than d (d>b) in one codeword, where c≥b+d-1 and b≤m.This paper proposed a new method of decoding fire code, which can correct two burst errors in one codeword, a main burs error in a length of not more than b bits and a sub-burst error in a length of not more than f bits (f≤r/2-b).After an exposition of the decoding algorithm has been made, the (224,184) shortened fire code is described above as an example for the design method of the decoder, and the system BER performance has been tested on the GSM simulation platform. The Simulation programs showed that the new decoding system significantly reduces the error rates. The decoding program can give full play to the burst-error-correcting capability of fire code.