(CRC Cyclic Redundancy Cod) . , Bk(b0,b1,,bn-1) - , Bi(bn-1,b0,,bn-2) . , , . , .
.
-
x ←
, k () k- 1
.
() n . b (x) n-1>k-1.
, b (x) , ( ) g (x), . .
, n , k - (n - k) . (n, k). n k
,
- .
b(x), .. ( CRC), .
1. . (n-1) .
2. g (x) .
.
3. , .. CRC (n k) .
.
.
2,
.
, . , .
CRC- (7,4) (1,1,0,0). .
1. n k = 3
(1,1,0,0,0,0,0).
2. ( ).
, .
3. , (1,1,0,0,0,1,0). , , CRC.
, n , .
|
|
, CRC- . (.3.3), 2 .
.
, , .
, , . . , j - .
.
, , ( 1), . , , .
.
.
, . , , . , , . , , , , N . , n, N, .
, (, ). 2 , . , , .
, - . , , CRC-16
.
L n . , (n-k) , . (1/2 n-k) .
16 , , = 32767 . , 32767 16 , .. .
, , 3.1.
3.1
CRC-8 | ATM, | |
CRC-10 | ATM, AAL | |
CCITT CRC-16 | HDLC, V.41 | |
CCITT CRC-32 | IEEE 802, V.42 |
- 10-3, . 111, 000. ( , ). ?
- IP-, 16- : (11111111 11111111, 11111111 00000000, 11110000 11110000, 11000000 1100000000).
- , . (1001). 1? 4 ?
- . 10 . 1 , . Pfr. :
- ,
- , .
- , .
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