66807

General description, Arbitrary prefix condition codes

Encoder can be divided into two parts: source encoderand channel encoder. For the given codę alphabet A=B of ihe length D.

•    at first, M source messages are encoded in source encoder.

•    then. in case of error control codę. codę words are processed in channel encoder.

Source data:	M=x=	{*........
Codę alphabet:	> II TT
Information codę words (before channel encoder):	{i}= 1 = {	i.....<i«} •
	1/ =[««•■	•Vl;i = L

where k, is length of the #-th i n for mat i on word.

Codewords (after channel encoder):    {w} = W = {w......w_M},

w, =[w_ir~w_v -w_ils]\i = \.....M ,

w_IJ=a_lor~ora_DJ = \.....u,,

where n_t is a length of the /-thcodeword.

in case of Information codę. channel decoder does not exist and

w. = i_f \n_i = k_t; i = 1.....M ,

in case of error control codę. I, is part of w, and /i, = n.

Error words (patterns):

{z}= Z = {z......z_N}

z. =[z„ -    ];/ = 1.....K.