error correcting codes/ Forward Error correction

convolutinal code
1. block by block basis
  1. BASIC : Repetion code , Hammin Code , Multi- dimentioanlal parity check code, repition code ,parity codes ,reed solomoon codes ,cyclic codes (e.g ha)
  2. More -Efficient : Reed Solomon Code ,Turbo Codes, LDP.The last two provide almost optimal efficiency
2. Decoded with Viterbi
block codes
1. biy-by-bit basis
ERRO CORRECTIONN
1. ARQ
  1. STOP -AND-WAIT ARQ
  2. GO BACK-N ARQ
  3. SELECTIVE REPEAT ARQ
2. HYBRID ARQ
  1. Messages are always transmitted with FEC parity data (and error-detection redundancy) A receiver decodes a message using the parity information, and.
  2. Messages are always transmitted with OUT FEC parity data (and error-detection redundancy ). f a receiver detects an error, it requests FEC informatio
  3. hybrid ARQ with soft combining : In practice, incorrectly received coded data blocks are often stored at the receiver rather than discarded, and when
    1. Chase Combining: every retransmission contains the same information (data and parity bits). The receiver uses maximum-ratio combining to combine the r
      1. Type 1 HARQ with MCR is called Chase combing
    2. Incremental Redundancy :every retransmission contains different information than the previous one. Multiple sets of coded bits are generated, each rep
      1. Type 2 n the type-II HARQ scheme [23], [24], instead of sending the same coded packets, the transmitter tries to construct and send additional coded p

Resumo de Recurso

	Criado por shamsuddeen2004 mais de 11 anos atrás