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Consider a 50 kbps satellite channel with a 500 milliseconds round trip propagation delay. If the sender wants to transmit 1000 bit frames, how much time will it take for the receiver to receive the frame?1. 250 milliseconds2. 20 milliseconds3. 520 milliseconds4. 270 milliseconds |
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Answer» Correct Answer - Option 4 : 270 milliseconds The correct answer is “option 4”. CONCEPT: Bandwidth: It is the speed of bit transmission in a channel or link per second. It is the number of bits per second that a channel, link, or network can transmit. Transmission time: It is the time between the first bit leaving the sender and the last bit arriving at the receiver. It can be calculated as : Transmission time = Message size ÷ Bandwidth Propagation time: The time required by the bit to travel from source to destination is called propagation time. It can be calculated as : Propagation time = Distance ÷ propagation speed Round Trip Time(RTT): It is a time to travel from source to destination and again come back to the source. It is twice of propagation time. CALCULATION: RTT: 500 millisecond Message size: 1000 bits Bandwidth : 50kbps RTT = 2 x Propagation time 1. Propagation time = RTT / 2 = \(\dfrac{500 \rm \ ms}{2}\) = 250 ms 2. Transmission time = \(\rm \dfrac{1000 \;bits}{50 \;kbps}\) = \(\dfrac{1000}{50\times1000\times10^{-3}}\)ms = 20 ms The total time for the receiver to receive the frame= Propagation time + transmission time = 250ms + 20ms = 270ms Hence, the correct answer is “option 4”. |
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