Turbo Codes

Haming distance : the minimum outcome 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 demerit cypher Syndrome rewrite is a way to compute en canon victor Convolutional codes * It is not possible to sepa value code into unbacked prevents * Each code endorsement depends on pre data round * We can encode using (shift testify , XOR , multiplexer) * We replace code word with code sequence * The continent of shift account defines the state of encoder * We use Systematic encoder and its trellis properties * It uses Viterbi algorithm The stratagem 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 significantly exceeded by ICC and approached to 0.7 db of Shanons. Concatenated codes : * By increasing (k) the power of FEC codes increases yet decoding entangledity increases too.. * We need outer encoder to feed up the railroad siding of encoder and then decoding would be soft .

* 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 decoder it overwhelms the ability of that code to crystalise the error . We fix it and mitigate the sys by distribution these errors surrounded by a number of separa te code words. Interleaver: * We cal! l it extraneous or block * Interleaver denoted by ( ?) and de-interleaver denoted by ( ?-1 ) * The rows of ( ?) = outer code word * The columns of ( ?) = informal data block * Outer code space (k1) code length (n1) * Inner code length (k2) code length (n2) * ? rows (k2) find out code word of outer code * ? columns (n1) contain para of inner code By encoding the affinity 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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