Performance: Selective Repeat
Error Free: U=1 if Nɮ?+1 N/(2?+1) otherwise
With Errors: Nr=? i Pi-1(1-P) =1/(1-P)
U=(1-P) if N>(1+2?) N(1-P)/(1+2?) otherwise
Note that we have simply divided the error-free sliding window
result by Nr, where, Nr = E [# transmitted frames to successfully
transmit one frame] = 1-P in this case...