1. Communications Infrastructure
Chapter 12

2. Early Infrastructure Telegraph 1844 Telephone 1877 Radio
News transmission
Business & event coordination
Telephone 1877
Personality at a distance
Radio
Wireless infrastructure formed

3. Early Networks Bell/AT&T regulated monopoly Common carrier
Goal of universal service
Common carrier
Must carry all messages
Cannot be message provider

4. Wireless Development Early radio 1890s Microwave towers – post-WWII
Wireless telegraph
Primarily 2-way communication
Later adapted to broadcasting
Microwave towers – post-WWII
Used for cable and telephone transmission
Satellites 1962
Transmitter/receivers launched into space
Digital cell phones 1995
Problems with technical standards

5. Broadband Infrastructure
Coaxial cable
Carry video from microwave towers
Fiber optics
Use lasers & glass strands to multiply channels
DBS
Expands broadcast signal via digitization

6. Transmission Technologies
Multiplexing
Sending multiple messages down single path
Use carrier waves in signal to distinguish messages
Coaxial cable
One wire wrapped by another
Broadband capacity

7. Transmission Technologies
Microwave
Directional antennas
Line of sight transmission
Multiple streams of communication
Satellites
Microwave in the sky
Geostationary orbits
‘Footprint’ = coverage area of transmission

8. Cable Systems

9. Switching Manual Mechanical Electronic Human operators
Machinery responds to electric inputs
Electronic
Use computer chips to perform millions of switches

10. Packet Switching Divides data into ‘packets’ TCP/IP and VOIP
Chunks of information with corresponding addresses
Packets distributed through network, then reassembled
TCP/IP and VOIP
Depend on digitization of voice, packetization of digital units

11. Local Networks

12. Terrestrial Broadband
Modem
Device on computer that converts analog to digital signals
DSL
Uses computerized signals and switching along traditional phone lines
Cable Modem
Carries digital signal alongside programming signals on coaxial cable
Power line
Electrical lines may be converted to carry digitized data

13. Wireless Transmission
Mobile phone
Compression & increase capacity for broadband
Pagers
Miniature radio receivers
Use ‘piggyback’ frequency on FM bands
Wireless Internet
WiFi: TCP/IP over wireless transmission
Hot spots abound in urban areas
LEO
Low earth orbit satellites
Useful where no towers are nearby or for broader signal

14. Cell Phones Coverage areas are hexagonal ‘cells’
Towers pass signal from cell to cell
Digital cellular
Smaller cells
Use GSM standard
3G phones that have computer functions

15. Infrastructure Services
Wireline services
POTS
CLASS
CLECs provide mainly business services
Wireless services
SMS
CLASS services
Cameras
Phone options

16. Infrastructure Services
Long Distance
Separated from local calls
Use interexchange carriers (IXCs)
Local-toll calls now competitive
Dial-around services
10-10
800 or 888 numbers
Billed per minute or flat rate
Mobile phones use flat rate as “free” long distance

17. Telephone Industry Local Long Distance International
Carries signals between customers in region
IntraLATA
Long Distance
Carries signals between local phone switches in:
different area codes
Different LATAs
International
IRCs carry international signals between countries

18. Telephone Networks

19. Telecommunications Policy
Subsidies
Discounts or grants to certain corporations or classes of customers
Access fees collected on long distance for local companies
ISPs pay no access fees
Low income & rural customers get subsidized

20. Universal Service Phones in 94 percent of American homes
85 percent of African-American homes
E-rate program
Universal service fees diverted to pay for Internet connections for schools, hospitals
90 percent of schools now connected
Deregulation
Different types of competition
Fewer resources to address social ills