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Wireless Infrastructure: Overview and Issues H. Scott Matthews February 24, 2003
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Homework #2 Average: 48/55
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Midterm Exam Handed out today, due Wed March 5
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Recap of Last Lecture Utils had become vertically integrated Deregulation changed this structure Partly to blame for transmission constraints Now a hierarchical jurisdiction to manage Despite 100 years of research and practice, overall system efficiency low
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Source: Lawrence Berkeley Labs; http://www.lbl.gov/MicroWorlds/ALSTool/EMSpec/EMSpec2.html
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Early Radio/Wireless Events More detail on other telephone/wireless: http://www.privateline.com/PCS/history2.htm http://www.privateline.com/PCS/history2.htm Wireless by induction/conduction/radiation Marconi: First ‘radio’ system created (1901) Application: ships - intended wireless telegraph 1906: Radio band-wave comm. - speech 1910: Ericsson - first car ‘telephone’ 1924: First mobile car ‘radio’ telephone 1927: US Federal Radio Commission started 1934: Federal Communications Commission Telephone & radio under jurisdiction - licenses for spectrum Early history - very/too close to industry to manage
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More Wireless Events 1958: Invention of integrated circuit (IC) In this era, FCC ‘lazy’ in giving spectrum 1973: First handheld cell phone in US Originally analog (handout) now digital Analog in 800 MHz range, Dig 800/1900 ‘Cellular’ networks - freq reuse and handoff Freq reuse allows more use of spectrum, manages potential ‘interference’ Handoff trades ownership of signal to other cells Antennas associated with cells Cell size can be 1-50km radius - digital 10km Some cells have hierarchy of smaller cells Base station manages freq and power of handsets
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AT&T Breakup Effects Originally AT&T monopoly on telephone service in US, broken up in 1980s Created ‘baby bells’ - RBOCs Intended to compete w/ each other 1990s - started merging Now provide wireless service in competition (e.g. Cingular = Bell South, Verizon = Bell Atlantic + NE bells, etc)
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Antenna/Cell Locations Generally want to have 90% of an area ‘covered’ and ‘usable’ 90% of time Includes base station/equip and antenna Siting depends on demographics, population, growth, road usage, future trends Don’t want too abandon cells, so choose now and add capacity/split cells later Height of antenna effects range of cell Consider absorption of natural environment (I.e. leaves on trees absorb some of signal!) Need more power in summer than winter Unlike rest of world, US was worried about backward compatibility when going A->D
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System Statistics (mid 2002) From CTIA Industry Surveys (US only) http://www.wow-com.com/industry/stats/surveys/ 135 million “subscribers” (all sectors) Still rapid growth, but slowing (50% penetration!) Almost 90% digital 131,000 ‘cell sites’ (each using 3-5kW power) About 500 billion wireless minutes used/yr Avg call length 3 minutes Number of wired ‘subscribers’ - about same And decreasing as DSL, mobile phones happen What are infrastructure management issues?
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Wired and Wireless Users Source: ITU World Telecom Development Report, March 2002
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Sample Wireless Telephone Coverage Map - What Is/Is Not Covered by this Manufacturer - and is this total US coverage?
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Other Issues Wireless not really wireless High dependence on wired (PSTN) network FCC - defined above - communications Regulates activities, mergers of telecoms State PUCs - also involved Industry Groups Big difference is less oversight of these companies now that monopoly effects lower
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