7/29/2019 BI LUYN TP CHNG 9

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Bi ging: Truyn s liu Chng 9: Pht hin v sa li

BI LUYN TP CHNG 9

I. CU HI N TP

1) Cho bit khc bit gia li mt bit v li bt (burst error)?

2) Trnh by nim m tha trong pht hin li?

3) Cho bit bn dng kim tra m tha dng trong truyn d liu?

4) Phng php pht hin n v d liu b li bng cch dng bit parity (VRC)?

5) S khc bit gia parity chn v parity l ?

6) Trnh by v phng php VRC v cho bit dng li khng pht hin c?

7) Quan h gia VRC v LRC?

8) Trnh by v phng php LRC v cho bit dng li khng pht hin c?

9) B pht, CRC kt ni vi n v d liu nh th no?10) Cho bit quan h gia kch thc CRC v b chia?

11) B kim tra CRC pht hin li nh th no?

12) Cho bit v iu kin dng a thc trong b CRC generator?

13) u im ca CRC so vi LRC?

14) Cho bit cc phng php pht hin li trong cc giao thc lp trn?

15) Php tnh dng cng cc segment trong b checksum generator v checker?

16) Trnh by cc bc to checksum?

17) B checksum checker pht hin li ra sao?

18) Checksum khng pht hin c li dng no?

19) Cng thc tnh s bit redundancy cn thit sa li bit, bit s bit d liu?

20) Mc ch ca m Hamming l g?

II. CU HI TRC NGHIM

21) Pht hin li c dng trong lpno ca m hnh OSI:

a. vt lb. kt ni d liu

c. mng

d. tt c u sai

22) Phng php pht hin li no baogm bit VRC ti mi n v d liucng vi bit VRC ca ton n v dliu:

a. VRC

b. LRC

c. CRC

d. Checksum

23) Cho bit phng php no dng phpb :

a. VRC

b. LRC

c. CRC

d. checksum

24) Cho bit phng php dng ch mtbit d trong n v d liu

a. VRCb. LRC

Bin dch: Nguyn Vit Hng Trang212

7/29/2019 BI LUYN TP CHNG 9

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Bi ging: Truyn s liu Chng 9: Pht hin v sa li

c. CRC

d. checksum

25) Phng php no c lin quan n nim a thc

a. VRCb. LRC

c. CRC

d. checksum

26) pht biu no m t li mt bit

a. mt bit b o

b. mt bit b o trong mt n vd liu

c. mt bit b o trong mt ln truyn

d. tt c u ng

27) Trong m ASCII, k t G (100 0111)c gi i nhng nhn li c kt D(100 0100), th l dng li g:

a. li mt bit

b. li nhiu bit

c. bt

d. khi phc c

28) Trong m ASCII, k t H (1001000)c gi i nhng nhn li c kt I (100 1001), th l dng li g:

a. li mt bit

b. li nhiu bit

c. bt

d. khi phc c

29) Trong phng php CRC, CRC cngha l g:

a. b chia

b. thng s (kt qu php chia)

c. s bit chia

d. s d

30) Trong phng php CRC, b chia ckch thc so vi CRC nh th no:

a. cng kch thcb. nh hn mt bit

c. ln hn mt bit

d. ln hn hai bit

31) Nu n v d liu l 111111, bchia l 1010, v d s l 110, hy cho

bit gi tr s b chia (divident) timy thu?

a. 111111011

b. 111111110

c. 1010110

d. 110111111

32) Nu n v d liu l 111111, bchia l 1010, v d s l 110, cho

bit s b chia (divident) ti my

pht?a. 111111000

b. 1111110000

c. 111111

d. 1111111010

33) Khi dng phng php parity ltrong pht hin li trong m ASCII,th s bit 0 trong mt k t 7 bit l:

a. chnb. l

c. khng chn, khng l

d. 42

34) Ti my thu, khi khng c li thtng ca checksum v d liu l:

a. 0

b. +0

c. phn b ca checksum

d. phn b ca d liu

35) M Hamming l phng php dng:

a. pht hin li

b. sa li

c. ng gi li

d. a v b

Bin dch: Nguyn Vit Hng Trang213

7/29/2019 BI LUYN TP CHNG 9

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7/29/2019 BI LUYN TP CHNG 9

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Bi ging: Truyn s liu Chng 9: Pht hin v sa li

III. BI TP

45) Cho bit nh hng ln nht canhiu bt 2ms ln d liu truyn vitc :

a. 1500 bps; 3 bit saib. 12.000 bps; 24 bit sai

c. 96.000 bps; 192 bit sai

46) Gi s dng parity chn (VRC), hycho bit VRC trong cc n v dliu sau (v mch to bit VRC):

a. 1001011; 0

b. 0001100

c. 1000000d. 1110111

47) My thu nhn c mu bit01101011. H thng dng VRC

parity chn, cho bit mu nhn cng hay sai (v mch kim traVRC)? Sai

48) Tm LRC ca khi cc bit sau:

10011001 01101111

49) Cho chui 10 bit: 1010011110 v bchia l 1011, tm CRC, kim tra likt qu.

50) S d l 111, n v d liu l10110011, v b chia l 1001, cho

bit n v d liu c li khng?

10110011111: 1001

51) Tm checksum ca cc chui bit sau.Gi s dng cc phn on 16 bit

10010011100100111001100001001101

52) Tm phn b ca 1110010001110011

53) Cng 11100011 v 00011100 v lyphn b. Gii thch kt qu

54) Trong cc n v d liu sau, tm s

d ti thiu cn c c th sa libit n:

a. 12

b. 16

c. 24

d. 64

55) To m Hamming cho chui bit10011101?

56) Tm VRC v LRC ca cc chui bitsau dng bit parity chn:

0011101 1100111 11111110000000

57) B pht gi 01110001, my thu nhn01000001. Dng VRC, hy cho bitmy thu c th pht hin li ckhng?

58) Khi bit sau s dng LRC, cc bit cli khng?

10010101 01001111 1101000011011011

59) H thng dng LRC vi khi d liu8 byte. Hy cho bit s bit d phigi i trong khi? Cho bit t s bithu ch trn tng s bit truyn?

8 bit, 64 / 72

60) B chia l 101101, hy cho bit CRC

c di l bao nhiu? 5 bit61) Tm gi tr nh phn tng ng cho

a thc: x8+x3+x+1. ;100001011

Bin dch: Nguyn Vit Hng Trang215