EECS Wireless oundations 3.Diversity Fundamentals of Wireless Communication,Tse&Viswanath
3: Diversity Fundamentals of Wireless Communication, Tse&Viswanath 1 3. Diversity
3:Diversity ireless oundations Main story Communication over a flat fading channel has poor performance due to significant probability that channel is in a deep fade. Reliability is increased by providing more resolvable signal paths that fade independently. Diversity can be provided across time,frequency and space. Name of the game is how to exploit the added diversity in an efficient manner. Fundamentals of Wireless Communication,Tse&Viswanath 2
3: Diversity Fundamentals of Wireless Communication, Tse&Viswanath 2 Main story • Communication over a flat fading channel has poor performance due to significant probability that channel is in a deep fade. • Reliability is increased by providing more resolvable signal paths that fade independently. • Diversity can be provided across time, frequency and space. • Name of the game is how to exploit the added diversity in an efficient manner
3:Diversity EECS Wireless Foundations Baseline:AWGN Channel y=x十w BPSK modulation x=士a 2-Q a2 SNR : No Error probability decays exponentially with SNR. Fundamentals of Wireless Communication,Tse&Viswanath 3
3: Diversity Fundamentals of Wireless Communication, Tse&Viswanath 3 Baseline: AWGN Channel BPSK modulation Error probability decays exponentially with SNR
3:Diversity ireless oundations Gaussian Detection P(ylx=uA)P(ylx=uB} Ify<(uA+uB)/2 Ify >(uA+uB)/2 choose uA choose uB y (UA+UB) uB 2 Fundamentals of Wireless Communication,Tse&Viswanath 4
3: Diversity Fundamentals of Wireless Communication, Tse&Viswanath 4 Gaussian Detection
3:Diversity EECS Wireless Foundations Rayleigh Flat Fading Channel y=hx+w h~CW(0,1) BPSK:x=ta.Coherent detection. Conditional on h, Pe =Q22SNR Averaged over h, 1 4SNR at high SNR. Fundamentals of Wireless Communication,Tse&Viswanath 5
3: Diversity Fundamentals of Wireless Communication, Tse&Viswanath 5 Rayleigh Flat Fading Channel BPSK: Coherent detection. Conditional on h, Averaged over h, at high SNR