Communication Modeling Phase Shift Keying PSK Modulation Base
Communication Modeling
Phase Shift Keying (PSK) Modulation Base band Signal X(t) 1 0 1 Band Pass Signal Y(t) © Tallal Elshabrawy 2
PSK Demodulation X(t)[2 cos 2(2πfct)] X(t)cos(2πfct) x Low Pass Filter X(t) 2 cos(2πfct) X(t)[2 cos 2(2πfct)] =X(t)[1+cos(4πfct)] X(t)[2 cos 2(2πfct)]=X(t) +X(t)cos(4πfct)] Base band Signal (i. e. , low frequency content) © Tallal Elshabrawy High frequency content 3
Orthogonality of sin and cos Functions X(t)cos(2πfct) X(t)[2 sin(2πfct)cos(2πfct)] x Low Pass Filter 0 2 sin(2πfct) X(t)[2 sin(2πfct)cos(2πfct)]=X(t) sin(4πfct)] High frequency content © Tallal Elshabrawy 4
Quadrature- PSK Modulation (QPSK) XI(t)cos(2πfct) XI(t) x X(t) cos(2πfct) Serial-to. Parallel + Y(t) XQ(t)sin(2πfct) XQ(t) x sin(2πfct) © Tallal Elshabrawy 5
QPSK Demodulation x Y(t) Low Pass Filter Parallel-to. Serial 2 cos(2πfct) x XI (t) Low Pass Filter X(t) XQ (t) 2 sin(2πfct) © Tallal Elshabrawy 6
Modeling of In phase Modulation Binary Encoder Cosine Modulation Transmitting Filter ES=A 2 -A © Tallal Elshabrawy A
Modeling of Quatrature phase Modulation Binary Encoder Sine Modulation Transmitting Filter ES=A 2 j. A -j. A © Tallal Elshabrawy
Modulation Constellations BPSK QPSK 1 b/s/Hz 8 -QPSK 16 QAM 3 b/s/Hz © Tallal Elshabrawy 2 b/s/Hz 4 b/s/Hz 9
Basic Communication Model in AWGN N TX S + R Channel Model R=S+N Detection Performance: l Correct Detection l S = S* l Erroneous Detection l S ≠ S* © Tallal Elshabrawy RX Detection S*
BPSK Modulation over AWGN Channels ES Energy per Symbol © Tallal Elshabrawy
BPSK Modulation over AWGN Channels Gaussian Noise 0 © Tallal Elshabrawy
BPSK Modulation over AWGN Channels Received signal distribution given 0 © Tallal Elshabrawy transmitted
BPSK Modulation over AWGN Channels Error Calculation given Symmetry of Gaussian Distribution Let 0 © Tallal Elshabrawy transmitted
BPSK Modulation over AWGN Channels Received signal distribution given 0 © Tallal Elshabrawy transmitted
BPSK Modulation over AWGN Channels Error Calculation given Let 0 © Tallal Elshabrawy transmitted
BPSK Modulation over AWGN Channels Signal Power & Symbol Error Performance 0 © Tallal Elshabrawy
BPSK Modulation over AWGN Channels Signal Power & Symbol Error Performance 0 © Tallal Elshabrawy
BER of PSK over AWGN Channels Notes: l Define N 0 Total Noise Power l N 0/2 Noise Power over Cosine axis, i. e. , σ2=N 0/2 l Each symbol corresponds to a single bit l Eb = E S l Pb = P e © Tallal Elshabrawy
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