Telecommunications & The Internet Basic Telecom Model

Transmission Speed

• BPS, bits-per-second, the amount of information that can be transmitted through a channel
• BAUD - a binary event, a signal change from positive to negative or vice versa.

Speed II

• At higher speeds a single signal change can transmit more than one bit at a time, so the bit rate will generally be higher that the baud rate.
• Transmission capacity is a function of the frequency, higher frequency means higher capacity

More Speed

• Bandwidth = range of frequencies that a channel can support (difference between highest and lowest frequency).
• Greater range means greater bandwidth.
• Greater bandwidth means greater transmission capacity.

Faster Yet

• Bandwidth is like pipe diameter.
• Larger diameter pipes can transmit more water in a given period of time.
• Personal Communication Services, PCSs, have a greater bandwidth than fiber optics.

Communications Processors

Front End
Processor
CPU
Controller
Computer
C
h
a
n
n
e
l
Multiplexer
PC
PC
PC
T
T
T
T
Concentrator
Channel

Network Topology

• Star Network
• Bus Network
• Ring Network

C
C
C
C
C
C
C
C
C
C
C
C
P
P
P

Networks

• Local Area Network, LAN
• Wide Area Network, WAN
• Value Added Network, VAN

Network Terms

• File server
• Print server
• Gateway - connects dissimilar networks
• Bridge - connects similar networks
• Routers - connects networks & directs traffic
• Similar networks = same network protocols

Transmission on LANs

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Chapter 8

• Token Ring
• can talk only when you have the token
• cost more than Ethernet
• better for high volume traffic
• Ethernet
• talk whenever you want
• send again if collision
• works best with low volume traffic