A series of information frames with a mean length of 1000

Question

Question :

A series of information frames with a mean length of 1000 bits is to be transmitted across a data link 4000km long at a data rate of 2Mbps.

If the link has a velocity of propagation of 2 *10⁸ ms^-1 and a BER of 10^-4 , determine the link efficiency using the following link protocols:

a) Idle RQ

b) Selective retransmission and a send window of 7

c) Go-back-N and a send window of 127 indicate the effect of bit errors on each of the result obtained.