Patent ID: 7266755
Filing Date: 2007-09-04
Classification: H03M

Abstract:
1. A method of transmitting signals comprising the steps of: receiving signals to be transmitted; source encoding said signals to build a variable length error code; channel encoding the variable length error code; and transmitting the channel encoded variable length error code, wherein said step of source encoding said signals to build the variable length error code comprises the sub-steps of: (1) initializing the needed parameters: minimum and maximum length of codewords L (2) generating a fixed length code C of length L (3) storing in the set W all the possible L (4) deleting all the words of the set W that do not satisfy the c (5) in the case where no word is found or the maximum number of bits is reached, reducing the constraint of distance for finding more words; (6) controlling that all words of the set W are distant of b (7) if the required number of codewords has not been reached, repeating the steps (1) to (6) until the method finds either no further possibility to continue or the required number of codewords; (8) if the number of codewords of C is greater than S, calculating, on the basis of the structure of the VLEC code, the average length AL obtained by weighting each codeword length with the probability of the source, said AL becoming the AL said building method being moreover characterized in that, considering that all distributions of number of codewords for the best VLEC codes have a similar curve allure of a bell shape type, it is defined an optimal length value Lm until which the number of codewords increases with their length, whereas it decreases after said value Lm, said definition allowing to apply the so-called “Ls optimization” method with avoiding the edges of the curve and to work locally.