Stop and Wait Link Utilization and Throughput

Question

Consider the stop-and-wait data link protocol operating over a link whose parameters are as follows: Tprop = d/v where d is the distance between transmitter and receiver in meters and v is signal propagation speed in meters per second, and Tf = L/R where L is the frame length in bits, and R is the link transmission rate in bits per second. Ignoring the Tack and Tproc , it is required to answer the following questions:

a) Plot the link utilization as a function of the link transmission, U(R) for R ϵ [0,∞).

b) Find the quantities lim 'R→ ∞' U(R) and lim 'R→ 0+' U(R).

c) Plot the link throughput in bit per second, Throbps(R) for R ϵ [0,∞).

d) Plot the link throughput in frames per second, Throfps(R) for R ϵ [0,∞).

e) Find the quantities lim 'R→ ∞' Throfps(R) and lim 'R→ 0+' Throfps(R).

The labels for all plots as well as all computed quantities should be in terms of the link parameters.

Answer 1

Actually I could observe how to answer the question U(R) = (L/R) / ((L/R) + 2 Tprob) Now: by taking the limit:

lim 'R→ ∞' U(R) = lim 'R→ ∞' (L/R) / ((L/R) + 2 Tprob)

put R = ∞, we get:

(L/∞) / ((L/∞) + 2 Tprob) = 0 / (0+2Tprop) = 0

the same for lim 'R→ 0+'.

Also, the same for the throughput.

After we get the limits, we can plot the graph easily according to the values we get.

Regards,