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The Next Generation of Wireless Local Area Networks

The Next Generation of Wireless Local Area Networks . Mark Ciampa. “Disruptive Technology”. Disruptive technology - A radical technology or innovation that fills a new role that an existing device or technology could not

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The Next Generation of Wireless Local Area Networks

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  1. The Next Generation of Wireless Local Area Networks Mark Ciampa

  2. “Disruptive Technology” • Disruptive technology - A radical technology or innovation that fills a new role that an existing device or technology could not • Examples: steamships, telephones, automobiles, word processors, and the Internet replacing sailing ships, telegraphs, horses, typewriters, and libraries • Disruptive technologies proven have profound impact upon society and how people live, work, and play

  3. Wireless • Today’s disruptive technology changing our world: wireless • Although wireless voice started revolution in 1990s, wireless data communications driving force in 21st century • Wireless data communications replacing need be tethered by cable to a network to surf Web, check e-mail, or access inventory records • Wireless made mobility possible to degree never before possible or rarely even imagined: users access same resources walking across college campus as can sitting at desk

  4. Wireless In Travel • Airlines - All domestic air carriers (except Allegiant Air and Spirit) offer or will offer wireless in 2010 • Airports - All 219 US airports (except Fairbanks, Van Nuys, Yampa Valley Regional, 5 Hawaii) offer wireless • Hotels - Over 25,000 • Trains - San Francisco Bay Area Rapid Transit (BART), Massachusetts Bay Transportation Authority (MBTA) • Limousine - Multiple major US metropolitan • Washington State Ferry system

  5. Wireless Changing All Sectors • Finance • Health Care • Manufacturing • Retail • Logistics • Government • Military • Construction • Education

  6. Wireless By The Numbers • Number of locations where wireless data services are available increasing 40% annually • By 2011 over 250 million wireless data devices will be sold (up from 22 million in 2003 and zero in 1999) • Virtually all laptop computers sold today have wireless data capabilities as standard equipment

  7. Wireless LANs • Same function of standard LAN but without wires • Based on IEEE standards • Also called Wi-Fi • Typical range 150-375 feet • Typical bandwidth 11-54 Mbps

  8. Standard WLAN

  9. Wireless LAN Cells

  10. IEEE WLAN Standards • 802.11 (1997) – 2 Mbps • 802.11b (1999) – 11 Mbps • 802.11a (2001) – 54 Mbps • 802.11g (2003) – 54 Mbps

  11. 802.11b • 11 Mbps • Direct Sequence Spread Spectrum (DSSS) • 3 non-overlapping channels • 2.4 GHz • Range 375 feet

  12. 802.11a • 54 Mbps • Orthogonal frequency-division multiplexing (OFDM) • 8 non-overlapping channels • 5 GHz • Range 150 feet

  13. 802.11g • 54 Mbps • Orthogonal frequency-division multiplexing (OFDM) • 3 non-overlapping channels • 2.4 GHz • Range 375 feet

  14. Limitations 802.11a/b/g • Speed – Only 11 to 54 Mbps • Coverage area – Limited • Interference – Most popular 802.11b/g 2.4 GHz crowded • Security – Useless WEP and weak WPA

  15. Next Generation WLAN • Speed – Up to 600 Mbps • Coverage area – Double indoor range, triple outdoor range • Interference – Use either 2.4 GHz or 5 GHz • Security – Require WPA2

  16. IEEE 802.11n-2009

  17. Next Generation WLAN • Development of 802.11n • 802.11n PHY layer • 802.11n MAC layer • 802.11n Security • Deployment strategies

  18. The Next Generation of Wireless Local Area Networks Development of 802.11n-2009

  19. IEEE Standard Bodies • WLAN standards set by Institute of Electrical and Electronics Engineers (IEEE) • IEEE uses 2 different internal groups • Working groups (WG), such as 802.3 (Ethernet), 802.15 (WPANs), WLANs (802.11) • Task Groups (TG), designated by a letter following number of WG (802.11b) • Function TG to produce draft standard standard, recommended practice, guideline, or supplement to present to WG • After TG’s work made public by creating a publication, function of TG complete and charter expires

  20. IEEE 802.11-2007 • Since 1997 IEEE approved 4 standards for WLANs (IEEE 802.11, 802.11b, 802.11a, 802.11g) and several amendments (802.11d, 802.11h, etc.) • To reduce “alphabet soup” in 2007 combined standards and amendments into 1 single standard • IEEE 802.11-2007, called the IEEE Standard for Information Technology—Telecommunications and information exchange between systems—Local and metropolitan area network—Specific requirements—Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications • Document officially retires all previous standards (802.11, 802.11a, 802.11b, 802.11d, 802.11g, 802.11h, 802.11i, 802.11j, 802.11e) • Combines into 1 comprehensive document

  21. IEEE 802.11 TGn • Sep 11 2004 IEEE formed Task Group n (TGn) begin work on dramatically new WLAN standard that increase speed, range, and reliability • Original estimate 802.11n ratified 2006 • TGn initially evaluated 62 different proposals • Due to delay Wi-Fi Alliance in Jun 2007 began certifying vendor products based Draft 2.0 and certified 500+ products including 80+ enterprise products in 2 years (not same as “Pre-n”) • “Anticipated” that products based on final 802.11n standard be backward compatible with Draft 2.0 devices

  22. IEEE 802.11n-2009 • IEEE 802.11n-2009 ratified Sep 11 2009 • Amendment to IEEE 802.11-2007 • 802.11n significantly improved over previous standards • Major impact is increase in maximum raw data rate from 54 Mbps to of 600 Mbps using multiple techniques

  23. 802.11n-2009 Features • Multiple-input multiple-output (MIMO) • 40 MHz channels • Data encoding • Data streams • Spatial Multiplexer • Aggregation • Block ACK • Transmission opportunity

  24. The Next Generation of Wireless Local Area Networks 802.11n-2009 PHY Layer

  25. OSI Model

  26. OSI vs. IEEE

  27. PHY Enhancements • Multiple-Input Multiple-Output (MIMO) • Spatial Multiplexing • Channel width

  28. The Next Generation of Wireless Local Area Networks 802.11n-2009 PHY Layer Multiple-Input Multiple-Output (MIMO)

  29. Tenn Genetic Defect

  30. Multiple-Lane Road

  31. SISO • SISO (Single-Input Single-Output) - Uses 1 transmit (TX) antenna and 1 receive (RX) antenna • IEEE 802.11a/b/g access points (APs) choose best antenna to send or receive a packet, but still uses 1 antenna at a given moment

  32. Best Antenna

  33. SISO

  34. MIMO • Long been known that multiple receive (RX) antennas can improve reception through selection of stronger signal or combination of individual signals at receiver • In mid-1990s research predicted large performance gains from using multiple antennas at both transmit (TX) and receive (RX), called MIMO (Multiple-Input Multiple-Output) • Using multiple antennas at receiver and transmitter has revolutionized wireless communications • Most high-rate wireless systems use MIMO technologies (802.11n, 4G mobile phone technology LTE, WiMAX)

  35. MIMO

  36. The Next Generation of Wireless Local Area Networks 802.11n-2009 PHY Layer Spatial Multiplexing

  37. Multiple Antenna Techniques • Adding antennas can increase capacity even though antennas transmit and receive on same frequency band simultaneously • Changes fundamental relationship between power and capacity per second per Hz • 2 techniques can be used to take advantage of multiple streams

  38. Spatial Diversity • Spatial diversity techniques increase reliability and range by sending/receiving redundant streams in parallel along different spatial paths between transmit and receive antennas • Use of extra paths improves reliability because unlikely all of the paths will be degraded at the same time • Spatial diversity can also improve range and some performance increase (gather larger amount of signal at receiver)

  39. Spatial Diversity

  40. RF Loss • Radio Frequency (RF) signals bounce impacted by types of objects and surfaces encounter • Many copies of the signal arrive at the receiver at different times having traveled along many different paths • Delay is enough cause significant degradation of signal at a single antenna because all copies interfere with first signal to arrive

  41. Absorption

  42. Reflection

  43. Scattering

  44. Refraction

  45. Diffraction

  46. Spatial Diversity • Spatial diversity can address RF loss • Each spatial stream sent from own antenna using its own transmitter • Because some space (10 centimeters) between each antennae, each signal follows slightly different path to receiver • Spatial diversity can address RF loss

  47. Spatial Multiplexing • Spatial multiplexing techniques increase performance by sending independent streams in parallel along the different spatial paths between transmit and receive antennas • It multiplexes multiple independent data streams, transferred simultaneously within one spectral channel of bandwidth • Improves performance because independent streams not slow down streams that are already being sent

  48. Spatial Multiplexing

  49. SISO vs. MIMO

  50. Spatial Multiplexing • Independent paths between multiple antennas can be used to much greater effect than simply for diversity to overcome RF loss • Spatial multiplexing uses independent spatial paths to send independent streams of information at same time over the same frequencies • Streams will become combined as pass across channel • Receiver will separate and decode

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