báo cáo mô phỏng bpsk, qpsk, 8-psk, 16-psk

TN CC THNH VIN TRONG NHM TI 11 LP D11CQVT01N

1. L Nht Quang

2. Kiu Quang Lc

3. Nguyn Trng Khi

4. Nguyn Hong Long

5. Nguyn Quc Vit

6. Nguyn Xun Cnh

BO CO M PHNG

S DNG SIMULINK KHO ST T L LI BT (BER) CA

CC PHNG PHP IU CH BPSK, QPSK, 8-PSK, 16-PSK

VI CNG SUT TN HIU TRN NHIU (SNR) 12dB

I. XC NH I TNG, MC TIU, YU CU.

o i tng: Cc phng php iu ch: BPSK, QPSK, 8-PSK, 16-PSK

o Mc tiu: Kho st, so snh, nh gi t l li bt (BER) ca cc phng

php iu ch.

o Yu cu: Ch kho st khi thay i cc phng php iu ch, cc thng s

khc c nh

II. THU THP V PHN TCH D LIU CA H THNG

M ha knh:

M ha knh cc tn hiu l thm vo cc thng tin gc vo cc bit d

bo v trc khi chng c pht qua knh truyn c nhiu.

M Hamming l mt m khi. Vi mi m>2 lun tn ti m hamming vi

cc thng s sau:

o Chiu di t m: N = 2M 1.

o Chiu di phn tin: K = 2M - M -1.

o Chiu di phn kim tra: M = N K.

y s dng m Hamming m ha, vi cc thng s sau:

o Chiu di bit kim tra l: M =5 bit.

o Chiu di t m: N = 25 1 = 31 bit.

o Chiu di phn tin: K = N M = 26 bit.

III. XY DNG M HNH.

u tin, ta to ra mt file m phng mi bng cch vo File > New >

Simulink Model.

Tip theo, t ca s Simulink Library Browser , ly cc khi sau:

Bernoulli Binary Generator: khi ngun pht, hay cn gi l

khi nh phn Bernourlli, khi ny to ra d liu s gm dy bit 0, 1

theo phn b Bernoulli.

AWGN Channel: Khi AWGN cng nhiu trng Gauss vo

trong tn hiu li vo. Tn hiu li vo v tn hiu li ra c th l s thc

hoc s phc. Nu tn hiu vo l thc th khi ny s cng nhiu Gauss

thc v to ra mt tn hiu thc li ra. Khi tn hiu li vo l phc,

khi ny cng tn hiu Gauss phc v to ra mt li ra tn hiu phc. Khi

s dng s thay i mode v i li vo phc, gi tr thay i ngang bng

thnh phn thc chia cho thnh phn o ca tn hiu li vo. Thng s

c th thay i c l Initial seed, Mode, Eb/No (dB), Number of bits

per symbol, Input signal power (watts), Symbol period (s).

Khi ny s dng khi Signal processing Blocksets Random

Source to ra nhiu. Thng s intial seed trong khi khi chy to

nhiu. Gi tr xc lp ban u (Initial seed) c th l s hoc vector m

di l s knh trong tn hiu li vo.

Hamming Encoder: khi m ha Hamming, c nhim v m

hocc bt u vo thnh chui bt u ra bng cch chn cch bit kim

tra li.

Hamminh Decoder: khi gii m hamming.

Error rate calculation: l khi tnh ton t l li bt, hoc t l

li Symbol ca tn hiu li vo.

Sau khi thm cc khi trn vo vng lm vic ca file m phng ta tin

hnh ni cc khi li v c nh hnh sau:

QPSK Modulator Baseband : iu ch tn hiu u vo s

dng phng php iu ch kha dch pha cu phng QPSK.

QPSK Demodulator Baseband : Thc hin gii iu ch, thc

hin nhim v ngc li khi iu ch QPSK.

Hnh 1: M hnh QPSK

BPSK Modulator Baseband : iu ch tn hiu u vo s dng

phng php iu ch kha dch pha nh phn BPSK.

BPSK Demodulator Baseband : Thc hin gii iu ch, thc hin

nhim v ngc li khi iu ch BPSK.

Hnh 2: M hnh BPSK

M-PSK Modulator Baseband : iu ch tn hiu u vo s dng

phng php iu ch kha dch pha M mc M-PSK.

M-PSK Demodulator Baseband : Thc hin gii iu ch, thc hin

nhim v ngc li khi iu ch M mc M-PSK.

Hnh 3: M hnh 8-PSK

Hnh 4: M hnh 16-PSK

Thit lp cc khi:

Khi: Bernoulli Binary Generator.

1. Probability of a zero: xc xut bt 0: 1/2.

2. Initial seed: Gi tr xc lp ban u: 61.

3. Sample time: 1

4. Samples per frame: s mu mi khung: 26.

5. Output data type: kiu double vi iu QPSK, 8-PSK, 16-

PSK v kiu boolean vi BPSK.

Hnh 5: khi Bernoulli Binary Generator

Khi: Hamming Encoder v Hamming Decoder

1. Codeword length N: chiu di t m: 31

2. Message length K, or M-degree primettive polinomial: chiu

di bn tin K hay a thc nguyn thy bc M

Hnh 6: Khi m ha Hamming.

Hnh 7: Khi gii m Hamming

Khi iu ch v gii iu ch BPSK:

Khi iu ch v gii iu ch QPSK:

Khi iu ch v gii iuch 8-PSK:

Khi iu ch v gii iu ch 16-PSK:

Khi AWGN Channel: khi ny dng thm nhiu vo knh

truyn, mc ch to ra mi trng gn ng vi thc t

Hnh 8: khi AWGN Channel

1. Initial seed: gi tr khi to: 67

2. SNR(dB) T s tn hiu trn nhiu: 12 dB.

3. Input signal power, referenced to 1 ohm (watts): cng sut tn

hiu ng vo tham chiu ti 1 ohm (watts): 1

Khi Error Rate Calculation:

1. Receive delay: thi gian tr: 0.

2. Computation delay: thi gian tr do tnh ton: 0.

3. Computation mode: entire frame: ch tnh ton ti mt

khung.

4. Output data: d liu ra hin th ln ca s Workspace.

5. Variable name: tin bin nhn d liu hin th.

Hnh 9: Khi Error Rate Calculation

IV. KIM TRA V XC NHN M HNH

- Sau khi hon thin m hnh, ta thy m hnh trn gn ging vi thc t, c

b ngun to chui bit vo gi lp d liu, bn thu v pht c b m ha,

gii m, iu ch v gii iu ch. Ngoi ra cn c khi to nhiu (AWGN)

v khi Error rate Calculation tnh ton li.

- M hnh trn c hai thng s u vo l ngu nhin l: D liu u vo

nhiu Gauss trn knh truyn, do tha c nguyn l Monte-Carlo. Do

vy kt qu m phng s c gi tr thc t.

V. THIT K V THC HIN TH NGHIM

1. Chiu di bit d liu:

Ln 1: 10.000.000 bit (10 triu bit)

Ln 2: 20.000.000 bit (20 triu bit),

Ln 3: 30.000.000 bit (30 triu bit).

2. Thay i ln lt chiu di bt m phng v cc phng php iu ch.

VI. THU THP S LIU VO PHN TCH.

Kt qu chy m phng BPSK:

Hnh 10: Chy 10 triu bit


Hnh 12: chy 30 triu bit

Kt qu chy m phng QPSK:

Hnh 13: chy 10 triu bit


Hnh 15: Chy 30 triu Bit

Kt qu chy m phng 8-PSK:




Kt qu chy m phng 16-PSK:




Loi iu

ch

Ln

BPSK QPSK 8-PSK 16-PSK

1 0 2.10-7 0.0086 0.1577

2 0 1.10-7 0.0086 0.1576

3 0 0,6667.10-7 0.0086 0.1576

Hnh 22: Bng gi tr li bit (BER) ca cc phng php iu ch

khc nhau.

VII. BO CO KT QU.

Qua qu trnh m phng v phn tch d liu ta thy:

o Cc phng php iu ch khc nhau cho t l li bit (BER) khc

nhau.

o Phng php BPSK cho t l li bit nh nht, phng php 16-PSK co

t l li bit ln nht.

o Khi tng chiu di bit d liu vo mi phng php iu ch, ta u

thy t l li bit (BER) gim v gim dn n mt gi tr, nh vy t l

li bit BER cng chnh xc khi chiu di bit tng.

Gii thch:

o Khi s mc iu ch tng, th khong cch Hamming gia cc symbol

gim, dn n t l li bit tng.

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