Communications Infrastructure Chapter 12

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

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

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

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

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

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

Cable Systems

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

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

Local Networks

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

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

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

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

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

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

Telephone Networks

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

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