Convolutional code telecommunication error correcting (1 résultats)

Taschenbuch. Etat : Neu. nach der Bestellung gedruckt Neuware - Printed after ordering - Please note that the content of this book primarily consists of articlesavailable from Wikipedia or other free sources online. Convolutionalcodes are used extensively in numerous applications in order to achievereliable data transfer, including digital video, radio, mobilecommunication, and satellite communication. These codes are oftenimplemented in concatenation with a hard-decision code, particularlyReed Solomon. Prior to turbo codes, such constructions were the mostefficient, coming closest to the Shannon limit.To convolutionally encodedata, start with k memory registers, each holding 1 input bit. Unlessotherwise specified, all memory registers start with a value of 0. Theencoder has n modulo-2 adders (a modulo 2 adder can be implemented witha single Boolean XOR gate, where the logic is: 0+0 = 0, 0+1 = 1, 1+0 =1, 1+1 = 0), and n generator polynomials - one for each adder (seefigure below). An input bit m1 is fed into the leftmost register. Usingthe generator polynomials and the existing values in the remainingregisters, the encoder outputs n bits.…