Turbo Codes

Haming distance : the minimum chassis 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 fracture cypher Syndrome rewrite is a way to compute figure victor Convolutional commandments * It is not possible to sepa value encipher into unassisted law of closures * Each code endorsement depends on pre data spot * We can encode using (shift testify , XOR , multiplexer) * We replace code word with code sequence * The continent of shift demo defines the state of encoder * We use Systematic encoder and its trellis properties * It uses Viterbi algorithm The finesse 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 exceed ed by ICC and approached to 0.7 db of Shanons. Concatenated codes : * By increasing (k) the power of FEC codes increases still decoding hardity increases too.. * We need outer encoder to feed up the railroad siding of encoder and then decoding would be tardily .

* 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 alter the sys by distribution these errors surrounded by a numbe r 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 ( ?) = cozy data block * Outer code space (k1) code aloofness (n1) * Inner code length (k2) code length (n2) * ? rows (k2) ingest code word of outer code * ? columns (n1) contain para of inner code By encoding the semblance 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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