a week from today from 11:30 to 2:00 on may 6 M-ary PAM each sig sends k=log2(M) bits the M-sigs are si = uip(t), 0<=i<=M-1 where p(t) is a pulse time-limited to T seconds and ui in {odd +/- (M-1)} energy in a sig is Esi = ui*ui*Ep avg energy/sig is Es = (MM-1)Ep/3 optimum rxer is input multiplied by p(t), into symbol time integrator, into thresh device det thresh, calc sig components out of correlator: ^ui = E(Z|si sent) = int<0,T>(uip^2(t)dt) = uiEp variance = nEp/2? adjacent means, thresholds in between means Pe for sigs is not all the same Pe(low) = Pe(high) < Pe(intermediateN) = Pe(intermediateM) intermediates are called interior points ends are called exterior points Pe(interior) ~~ 2Pe(exterior) Pe0 = Q(sqrt(2Ep/n)) Pei = 2Q(sqrt(2Ep/n)) prob of symbol error in terms of avg symbol energy is Pe& = 2(M-1)/M * Q(sqrt(6Es/(MM-1)n)) = 2(M-1)/M * Q(sqrt(6log2M/(MM-1) * Eb/n)) prob of bit error will depend on which sig is sent and the assignment of bits to symbols the most common sig errors are for adj symbols bits should be assigned to min bit errors so adj symbols should differ by only 1 bit (gray code) with M-ary PAM sig, we must increase energy/bit to achieve same perf as in binary PAM in bin PAM, we require B Hz to send data at a rate of Rb bits/sec in M-ary PAM, we can send data at a rate of kRb over this BW, or we can send data at a rate of Rb bits/sec using B/k Hz these results hold for M-ask as well, where p(t) = p'(t)cow(wct + phi) M-QAM sigs are txed by si = ai*sqrt(2/T) * cos(wct) + bi*sqrt(2/T)*sin(wct) where ai in (odds from +/-(M'-1)) and bi in (odds from +/-(M"-1)) and M = M'M" optimum rxer: 2 branches with sin and cos component multipliers, integrated and pushed into decision devices 2 indepent decision devices prob of symbol error varies depending on interior vs exterior and corner points Pe(corner) = Pe(interior)/2 Pe(edge) = 3Pe(corner)/2 2 correlators are in-phase and quadrature arranged in a rectangle quadrature determines row, in-phase determines column need to use gray code here as well, but a little more complicated because it's 2 dimensions 16-PSK arranged on a single circle, dividing the arcs evenly