Status of Next Generation Cellular and Wireless Local Area Networks and Current Research Activities

1. Status of Next Generation Cellular and Wireless Local Area Networks and Current Research Activities Mohsen Guizani Computer Science Department Western Michigan University mguizani@cs.wmich.edu

2. Western Michigan University • WMU is located in Kalamazoo, Michigan • WMU is one of 15 Michigan state schools • WMU has more than 28,000 students • The Computer Science is home to about 400 students • CS has 18 faculty members, 5 full professors, 7 associate professors, and 6 assistant professors.

3. Outline • Introduction • Cellular Coverage in the United States • Current Problems in the Telecommunications Industry • Review of Cellular Technologies • Wi-Fi: Competing or Complementary Technology? • The Future • Current Research Activities • Conclusions

4. Current Research Activities • Research Goal • 1x EV-DV Architecture • Resource Allocations Techniques • Cross Layer Design Overview • Intelligent Network QoS Protocols • Intelligent Network QoS Validation Protocol • Wireless QoS Based Routing Protocol

5. Introduction • A combination of factors has led to the current wireless situation in the US, which is rather poor in many respects • Rapid technological change • Rapid change in way people use technology • Poor business and investment decisions • Unrealistic expectations for new technologies • Competition on features and packages rather than underlying infrastructure • More thinking and intelligent decision making in future should enable vastly improved wireless service

6. Cellular Coverage in the US: Reason for Poor Coverage • Coverage is similar (often poor) because all providers use the same antenna towers • Much of the engineering behind tower placement is done in the old days of 3 watt cell phones at 800 MHz in cars with external antenna; in this day and age, the is much lower-powered units inside buildings or cars with no external antennas • NIMBY (“not in my backyard”) syndrome: Wealthy neighborhoods refuse to allow unsightly antenna towers

7. Cellular Coverage in the US (Continued) • Call by one of the authors from Baltimore, MD to Washington DC Dulles International Airport interrupted seven times due to coverage gaps—partly ascribed to the fact that there are five major cellular providers each of which has to build an entire network • The Yankee Group estimates that it would take $50B to $100B to bring cellular system up to snuff • Carriers do not have that kind of money • Would not solve political problems • Convenience trumps service quality • Relatively few people have abandoned landline phones

8. Cellular Coverage in the US (Continued) Source: Wall Street Journal, 4/15/04

9. Cost Constraints • Minimal revenue per minute of air time • Brutal competition • Availability of free airtime and long distance packages • No “killer app” has ever materialized • Not cameras and ability to send photos • People want dependable voice communications • Cellular phones unsuitable as wireless modems • Promoters did not consider human factors • E-mail already well-served by dedicated devices such as the popular Blackberry by RIM

10. Cost Constraints (cont.) • Access to the Internet is done while at rest • Coverage problems would interrupt most operations if in motion • Cannot really do anything while driving or walking • Screen is too small • Competing technologies such as Wi-Fi are much better

11. Problems

12. Problems (Continued)

13. Problems (continued)

14. Problems (continued)

15. 1G Cellular Technology Advanced Mobile Phone Service (AMPS) • Analog • Widest coverage, much wider than digital systems • Phased out by 2008 • Of concern to users of OnStar, which employs it—digital systems’ coverage poor by comparison • Being phased out because newer systems can support more customers per unit of bandwidth—bandwidth is most precious resource

16. 2G: GSM, CDMA, IS-95-a, iDEN Global System Mobile (GSM) • Initially Group Speciale Mobile; renamed Global System Mobile to give it an international flavor • Combined TDMA/FDMA system • Offered by AT&T, T-Mobile, and Cingular in the US • Advantage: With unlocked tri-band phone, users can have cellular service worldwide • Problem: Outside the US, reciprocal agreements with US providers expensive—$~4 per minute for airtime • Better solutions: Get subsidy unlock code for phone used in US—buy SIM card when abroad from kiosk; buy cheap tri-band phone in the US, then buy SIM card when abroad

17. 2G (Continued) Coded Division Multiple Access (CDMA) • Offered by Sprint and Verizon in the US • Verizon recently launched high-speed data service based on Phase 1 Evolution Data Only (1xEV-DO) in Washington, DC and San Diego, CA • Can handle the largest number of users per unit BW; most economically attractive

18. 2G (continued) Time Division Multiple Access (TDMA) • Use declining • Offered by AT&T and Cingular in the US Integrated Digital Enhanced Network (iDEN) • Developed by Motorola • Based on TDMA • Offered by Nextel in the US • Likely to be phased out in favor of CDMA-2000

19. 2.5G • So-called 2.5 or 3rd generation wireless technologies unlikely to be profitable, especially given prices paid for spectrum • Main thrust is higher speed data • Cannot compete with Wi-Fi • Nextel is planning to bypass altogether • What is needed is data rate of >2 Mbps

20. Beyond • Various generations of cellular telephony more important to providers than users • Maximize revenue per unit bw • Users care more about features, cost, dependability • Many features being pushed are of dubious value • Multimedia Messaging Service (MMS) • Short Messaging Service (SMS) • Walkie-talkie feature • Reduces connect time to ~2 second versus 15 second dial time • Games • Downloadable ring tones • Replaceable covers

21. Wi-Fi: Is It Really a Good Idea? • IEEE 802.11b • Caught on very fast; manufacturers incorporate Wi-Fi chips in laptops; hopes are that this will be the new “killer app” • Wireless LAN equipment sales have been growing—Gartner Group says 2002 spending on all vendors is ~$2.3B; end-user spending increasing by about 50 percent for the last two years

22. Wi-Fi: Security Issues • Algorithm is used, Wired Equivalent Privacy (WEP) discredited • Encryption key length too short • Initialization vector implementation flawed • Scheme can be cracked quickly • Successor, WPA, is patch—not a fix • Vulnerable to broadband jamming, unless it uses frequency hopping as does Bluetooth

23. Wi-Fi: Security Issues(Continued) Users do not seem to care • 70 percent of installations have not even implemented what little security measures there are • Incompatibilities among vendor equipment mean that Wi-Fi hot spots must implement lowest common denominator, i.e., no security • Wi-Fi user sitting next to “me” at Starbuck’s can intercept all transmissions to/from my computer • Doctor files in “my” computer • Impersonate “me” after “I” have logged off

24. Wi-Fi: Security Issues(Concluded) Lack of scalability • PKI has not provided desired solution • Efficiently and rapidly propagating information about revoked encryption keys through large networks • Problem of where to store private or secret key safely in a manner that hacking cannot compromise • Smart cards may be the only viable solution, but most laptops have no smart card reader • Could be added through USB port

25. Wi-Fi: Business Model • No clear business model • Nobody making money off of Wi-Fi • Not a cost center, but a gimmick to attract customers • Issue of illegal use of Wi-Fi connectivity—who is liable? • Maryland homeowner recently held liable when someone used his hot spot for an illegal act • Airports and other such places look to Wi-Fi to recoup money no longer received from pay phones • Travelers unlikely to agree to open yet another account unless all places they frequent use same account

26. Wi-Fi: Setup Difficulties and Network Incompatibilities • Complex Windows’ network setup menus and options to set the SSID for each hotspot provider’s Access Point • Most non-technical laptop users are disinclined to do so • Technical help from kid behind counter at Starbuck’s, etc., is a losing proposition • Proliferation of different Wi-Fi hotspot providers means that users must open a separate account for each • T-Mobile account at 2,100 Starbuck’s or Kinko’s • Cometa account at MacDonald’s • FatPort account in Canada • Surf & Sip account at Foley’s Irish pubs • Toshiba account at Arizona’s Circle K stores • Waypoint account at a few select hotels

27. Wi-Fi: User Fees and Speed Problems • User fees • Disinclination of users to pay more access fees • Many feel they are already paying their Internet dues through home subscriptions • Lots of free Wi-Fi access points • From businesses that want to attract customers for their main product • Speed problems • Chips implementing 802.11b with WEP force all users to speed of slowest user at the hotspot

28. Wi-Fi: Incompatibilities and Spectrum Shortage • Incompatibilities between WEP and WPA • Problem has not received much press because commercial hotspots have not enabled either—due to vendor incompatibilities • Spectrum shortage • 802.11a has more spectrum allocated to it (which allows it to accommodate more concurrent users)—however has not yet caught on • Dual 802.11b/a access points and especially client user’s PCMCIA cards are very expensive; suffers from the same security vulnerabilities

29. Wi-Fi: Standards and Scalability • Standards • 802.11i, 802.11x, and 802.11e “standards” waiting in wings in various levels of agreement as to their final specs • Problem is that millions of deployed laptops and hotspots may make upgrade to better standards impossible • Scalability • Inherently not scalable • Operates in crowded unlicensed band with baby monitors, cordless phones, Bluetooth devices, microwave ovens • Limited number of channels—3 versus 8 for 802.11a

30. Wi-Fi: Summary • Wi-Fi has not really taken anything away from cellular • Cell phones are not as practical as wireless modems at 3 Kbps to 8 Kbps • Some CDMA systems (Sprint) encouraged use of cell phone itself for e-mail and messaging; however not practical due to the small size of the keyboard • Human factors: do people really want to make coffee shops another extension of their office?

31. The Future • Despite problems, wireless is here to stay • Convenience dictates that it users will demand it • Problems of “last mile” access • Need to set up and tear down networks quickly • Mobile ad hoc networks (MANETs) for military and for emergency responder use • Sets the stage for determining who will emerge victorious in future • Go beyond solving current problems and anticipate and solve future problems—foregoing; societal preferences, economics, scalability, and regulatory issues

32. The Future (Continued) • Realities of wireless solutions • Must be commercialized within months • Cannot hope for any regulatory protection given in the past to telecommunications monopolies • Will have to compete fiercely with other technologies for customer dollars—and hence for survival • Three issues of importance • Spectrum • Technology available to address problems • Socio-political issues

33. The Future (Continued) • Really is not a spectrum shortage • Even in areas such as Washington, DC, only about 20 percent of available cell phone spectrum used during peak hours • Real problem is more intelligent and efficient use of available spectrum

34. Technology Available to address Problems • Ultra-wideband • Wi-Max • Wireless mesh networks • Smart antennae • Software radios

35. Technology Available to address Problems (cont.) Ultra-wideband • Uses short (~1 nsec) pulses which correspond to about 1 GHz bandwidth • Such pulses with 1 W peak power and repetition rate of 108 have average power of 100 mW spread over 1 GHz • Interference in a 1 kHz channel ~ 0.1 mW • FCC has allocated 3.1-10.6 GHz band • Currently in use by satellite uplinks and downlinks • Data rates up to 500 Mbits per second can be accommodated versus 700 kbps for Bluetooth

36. Technology Available to address Problems (cont.) Ultra-wideband (Concluded) • UBW likely to become standard of choice for home networks • IEEE standard is 802.15.3a • Uses TDMA • Wireless Personal Area Network (WPAN) • 245 devices up to 90 m • Data rates 11 – 55 Mbps, declining with distance • AES encryption • Discussions now about dividing Expected shipments of UWB equipment

37. Technology Available to address Problems (cont.) Wi-Max • Another emerging technology • Intended for distances up to 50 km at data rates up to 70 Mbps • Intended to provide broadband service to replace “last mile” where this is not cost-effective with conventional technology • May also take up some of the functions of Wi-Fi

38. Technology Available to address Problems (cont.) Wireless mesh networks • Low-powered systems that pass messages from node to node on their way to their destination, not unlike what Internet nodes do with e-mail and other Transmission Control Protocol/Internet Protocol (TCP/IP) traffic • Any one node’s RF power output needs to be no more than what is required to close the link to the next nearest nodes • Redundant paths enhance the likelihood of end-to-end message integrity • Inherent is frequency reuse • Similar to old Ricochet network which went bankrupt because high costs of installation could not be recouped with small base of users

39. Technology Available to address Problems (cont.) Smart antennae • Two stations communicating by wireless have absolutely no excuse for using omni-directional antennas • If each end could beam all of its RF energy towards the direction of the intended receiver, the RF spectrum would experience a massive increase in availability with no new frequency allocations • Beam forming can be computer-controlled for adaptive beam forming • In case of cellular base stations can be fast enough to accommodate vehicular users • In case of Wi-Fi can extend range; SF startup, Vivato, working on 128 beam implementation

40. Technology Available to address Problems (cont.) Software radios • Software-configurable cell phones • To handle multiple systems, also Wi-Fi • Eliminate need to buy new cell phones every year or so

41. Socio-Political Issues • Diverging international standards—China adopting its own wireless LAN standard, basically Wi-Fi with improved security • Ad hoc implementations—Some locations installing their own area-wide Wi-Fi to deal with problem of multiple accounts (Cerritos, CA) • Voice over IP • Currently a major trend, or at least major hyped trend • Promises many benefits • But many legal and regulatory issues unresolved, especially related to emergency response and USF

42. Conclusion • Rate of change in telecommunications has been unprecedented • International cellular and wireless LAN industries have had two decades of gross miscalculations • Multibillion dollar bankruptcies • Endless miles of unused fiber optic cables • Digital cellular coverage in the US which is poor even by third world country standards • Wireless LAN standards whose lack of security has been an embarrassment • Hodge-podge of mutually incompatible cellular standards

43. Conclusion (continued) • Industry now has the opportunity to plan wisely ahead • Forego the short-term gimmickry of downloadable ringing tones and designer-face-plates • Use US technological prowess in evolving technologies such as software radios, ultra-wideband, and smart antennas to forge standards that will with-stand the test of time and of consumer acceptance

44. Current Research Activities • Research Goal • 1x EV-DV Architecture • Resource Allocations Techniques • Cross Layer Design Overview • Intelligent Network QoS Protocols • Intelligent Network QoS Validation Protocol • Wireless QoS Based Routing Protocol

45. Motivations • High bit-rate applications (www, file transfer, full motion video) impose strong requirements/needs on the system capacity • Studies confirm a productive gain of between 7-8 hours a week when business users are equipped with mobile PCs and wireless access. • All-IP applications: end to end packet-switched network

46. Goals • To develop a new dynamic and intelligent resource allocation technique for optimizing the average throughput of the wireless system. • Maximize the spectral efficiency and the number of users supported. • Develop QoS based protocol in the upper layer to assure the level of service required.

47. Intelligent Network QoS Validation Protocol Engine Network QoS MAC/Network QoS Mapping Layer MAC Layer Res. Alloc. Physical Layer Block Diagram

48. Competing technologies

49. CDMA Family • cdmaOne - IS-95A (2G) - IS-95B (2.5G) • CDMA 2000 1x (3G) 2000 • CDMA 2000 3x MC (3G) 2001 • 1xED-DO (3G) 2002 • 1xEV-DV (3.5G) 2003

50. IS-95A • 2G – 1995 • Upto 14.4 kbps data rates • Used exclusively for circuit-switched voice • Used Convolutional channel coding • Used BPSK (fixed) modulation technique * BPSK: Binary Phase Shift Keying