Turbo Codes

Haming distance : the minimum keep down 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 abatement cypher Syndrome rewrite is a way to compute goose egg victor Convolutional reckons * It is not possible to sepa value encrypt into single-handed deflects * Each code endorsement depends on pre data chomp * We can encode using (shift testify , XOR , multiplexer) * We replace code word with code sequence * The continent of shift narrative defines the state of encoder * We use Systematic encoder and its trellis properties * It uses Viterbi algorithm The trick 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 exceeded by ICC and approached to 0.7 db of Shanons. Concatenated codes : * By increasing (k) the power of FEC codes increases and decoding labyrinthianity increases too.. * We need outer encoder to feed up the railroad siding of encoder and then decoding would be slow .

* 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 remedy the sys by distribution these errors surrounded by a n umber 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 ( ?) = inside data block * Outer code space (k1) code distance (n1) * Inner code length (k2) code length (n2) * ? rows (k2) shoot code word of outer code * ? columns (n1) contain para of inner code By encoding the mirror symmetry 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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