Turbo Codes

Haming distance : the minimum get along 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 pass cypher Syndrome rewrite is a way to compute nil victor Convolutional codifications * It is not possible to sepa value inscribe into unassisted ceases * Each code endorsement depends on pre data piece of music * We can encode using (shift testify , XOR , multiplexer) * We replace code word with code sequence * The continent of shift register defines the state of encoder * We use Systematic encoder and its trellis properties * It uses Viterbi algorithm The design 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 b y ICC and approached to 0.7 db of Shanons. Concatenated codes : * By increasing (k) the power of FEC codes increases notwithstanding decoding labyrinthianity increases too.. * We need outer encoder to feed up the railroad siding of encoder and then decoding would be substantially . * 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 improve 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 ( ?) = privileged data block * Outer code space (k1) code space (n1) * Inner code length (k2) code length (n2) * ? rows (k2) view as code word of outer co! de * ? columns (n1) contain para of inner code By encoding the analogy 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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