1. 3. Television channels are 6 MHz wide
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 = 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 signal-to-noise ratio is 20 dB, what is the maximum achievable data rate?
B = 3 kHz = Hz
S/NdB = 20 dB
S/NdB = 10 log10S/N
20 = 10 log10S/N  2 = log10S/N
S/N = 102 = 100
Dengan teorema Shannon :
C = B log2(1+S/N)
C = 3*103*log(1+100)
C = 3*103*6.656 = *103 bps
C = kbps

2. 5. What signal-to-noise ratio is needed to put a T1 carrier on a 50-kHz line?
T1 carrier mempunyai C = 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 =
1+S/N =  S/N =
S/NdB = 10 log10S/N
S/NdB = 10*log
S/NdB = 10* = dB

3. 41. Three packet-switching networks each contain n nodes
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
Best : 2 hop
Worst : 2 hop
Average : 2 hop
RING (2 arah) Best : 1 hop
Worst : n/2 hop
Average : n/4 hop
MESH (full connected)
Best : 1 hop
Worst : 1 hop
Average 1 hop
Average untuk RING
N=genap  Avg = N=ganjil  Avg =