Nama : I Wayan Angga Wijaya Kusuma

NIM : 11/326013/PTK/07847

Tugas Komunikasi Data

Problem :

1. A non-periodic composite signal contains frequencies from 10 to 30 KHz. The peak

amplitude is 10 V for the lowest and the highest signals and is 30 V for the 20-KHz

signal. Assuming that the amplitudes change gradually from the minimum to the

maximum, draw the frequency spectrum.

2. What is the total delay (latency) for a frame of size 5 million bits that is being sent on a

link with 10 routers each having a queuing time of 2 μs and a processing time of 1 μs. The

length of the link is 2000 Km. The speed of light inside the link is 2 x 108 m/s. The link

has a bandwidth of 5 Mbps. Which component of the total delay is dominant? Which one

is negligible?

Solution :

1. Frequencies = 10 to 30 KHz

Bandwidth = 30 – 10

= 20

Amplitude = 10 V for the lowest and the highest signals, 30 V for the 20 KHz

Frequency spectrum :

amplitude (V)

30

10 Frequency (KHz)

10 20 30

2. Frame size 5 million bits sent on a link with 10 routers each having a queuing time of 2 μs

and a processing time of 1 μs.

The length of the link 2000 Km.

The speed of light inside 2 x 108 m/s, Bandwidth = 5 Mbps

Latency = Tpropagation + Ttransmission + Tqueuing + Tprocessing

Tpropagation = Distance/Propagation Speed

= 2 x 106

2 x 108

= 10 ms

Ttransmission = Message Size/Bandwidth

= 5 x 106

5 x 106

= 1 s

Tqueuing = 10 x 2 μs = 20 μs

Tprocessing = 10 x 1 μs = 10 μs

Latency = Tpropagation + Ttransmission + Tqueuing + Tprocessing

= 10 ms + 1 s + 20 μs + 10 μs

= 1.01003 s

The dominant of component is Ttransmission and the negligible of component is

Tqueuing.