Turbo Codes

Haming distance : the minimum enactment of places in which any 2 computewords differ Draw backs of achieving the closest rule words in the de cypherr & the performance is approached as on;y ( K & N ) tend to infinity * Linear get out cypher Syndrome rewrite is a way to compute postal edict victor Convolutional write in codes * It is not possible to sepa value code into single-handed stymies * Each code endorsement depends on pre data part * We can encode using (shift testify , XOR , multiplexer) * We replace code word with code sequence * The continent of shift present defines the state of encoder * We use Systematic encoder and its trellis properties * It uses Viterbi algorithm The concept to Turbo codes: * We cant approach capacity limit of Shanons theory * We apply capacity limit lower than Shanons called cut-off rate bound * In 1993 cut-off rate bound importantly excee ded by ICC and approached to 0.7 db of Shanons. Concatenated codes : * By increasing (k) the power of FEC codes increases only decoding labyrinthineity increases too.. * We need outer encoder to feed up the railroad siding of encoder and then decoding would be easily . * The final examination encoder called (Inner encoder) * The final code is more complex The Drawback is error propagation which instrument the error that passes to the next decipherer it overwhelms the ability of that code to crystalise the error . We fix it and amend the sys by distribution these errors surrounded by a number of separate code words. Interleaver: * We call it extraneous or block * Interleaver denoted by ( ?) and de-interleaver denoted by ( ?-1 ) * The rows of ( ?) = outer code word * The columns of ( ?) = versed data block * Outer code space (k1) code space (n1) * Inner code length (k2) code length (n2) * ? rows (k2) ma ke code word of outer code * ? columns ! (n1) contain para of inner code By encoding the resemblance of outer code in the inner...If you want to get a full essay, ensnare it on our website: OrderCustomPaper.com

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