Finding the data rate of a channel

Question

Consider a channel with source and target having distance between them of 10km. Propagation delay is 10 microsec/km. What will be the data rate of the channel if the RTT is equal to the transmission delay and packet size is 125 bytes?

a) 5MBps

b)5Mbps

c)10KBps

d)15kbps

Answer 1

Round trip delay is the delay involved in a round trip in a channel from sender to receiver and back to sender from receiver.Hence,

R.T.T = 2 * P.T. as we know propogation time is time spent in a channel from sender to receiver or vice versa.

According to the question,

R.T.T = T.T(Transmission Time)

Also we know that transmission time = data size / data rate 

And we are given P.T./km = 10 μs and distance = 10km so P.T = 100 μs , so R.T.T = 200 μs

Given data size = 125 bytes = 1000 bits .Hence we have the equation,

10³/x = 200/10⁶     which gives x = 10⁶ * 1000 / 200 = 5 * 10⁶ bps = 5 Mbps

Hence , B) is the correct option.