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3. Television channels are 6 MHz wide. How many bits/sec can
be sent if four-level digital signals are used? Assume a
noiseless channel.
Menggunakan teorema Nyquist :
B = 6 MHz = 6.106 Hz
M = 4 level tegangan sinyal digital
C = 2B log2M
C = 2*6*106 log24 = 12*106*2 = 24 Mbps
4. If a binary signal is sent over a 3-kHz channel whose signalto-noise ratio is 20 dB, what is the maximum achievable data
rate?
B = 3 kHz = 3.103 Hz
Dengan teorema Shannon :
dB
S/N = 20 dB
C = B log2(1+S/N)
C = 3*103*log(1+100)
S/NdB = 10 log10S/N
C = 3*103*6.656 = 19.975*103 bps
20 = 10 log10S/N  2 = log10S/N
C = 19.975 kbps
S/N = 102 = 100
5. What signal-to-noise ratio is needed to put a T1 carrier on a 50-kHz
line?
T1 carrier mempunyai C = 1.544 Mbps = 1.544*106 bps (halaman 105)
B = 50 kHz = 5*104 Hz
Dengan teorema Shannon :
C = B log2(1+S/N)
1.544*106 = 5*104*log2(1+S/N)
30.88 = log2(1+S/N)
1+S/N = 230.88
1+S/N = 1976087932.808  S/N = 1976087931.808
S/NdB = 10 log10S/N
S/NdB = 10*log101976087931.808
S/NdB = 10*9.2958 = 92.958 dB
41. Three packet-switching networks each contain n nodes. The first
network has a star topology with a central switch, the second is a
(bidirectional) ring, and the third is fully interconnected, with a wire
from every node to every other node. What are the best-, average-,
and-worst case transmission paths in hops?
STAR
RING (2 arah)
MESH (full connected)
Best : 2 hop
Best : 1 hop
Best : 1 hop
Worst : 2 hop
Worst : n/2 hop
Worst : 1 hop
Average : 2 hop
Average : n/4 hop
Average 1 hop
Average untuk RING
( n / 2 ) 1
n/2
( n 1) / 2
x

N=genap  Avg = 
 x N=ganjil  Avg = 2 *
x
x 1
x 1
n 1

x 1