High-speed Internet Access: Wireless and WiFi

Transcription

1 High-speed Internet Access: Wireless and WiFi Richard S. Wolff, Ph. D Montana State University Department of Electrical and Computer Engineering. [email protected]

2 Wireless: lots of technologies choices The bandwidth perspective Speed bps 100 M 10 M 1 M 100 K BT = Bluetooth H2 = Hiperlan 2 PDC = Personal Digital Cellular H b 5.5/11 Mb PBCC BT WCDMA EDGE cdmaone GPRS1X EV-DC, 3X??? 10 K AMPS G PDC cdma2000 GSM 1X TDMA cdmaone G 2.5G 3G 3.5G 4G

3 Bandwidth available is inversely proportional to range

4 Methods of media access Media access Random access Decentralized resource management Random, send at will : ALOHA Sense first, then send: CSMA Controlled access One station manages resources FDMA TDMA CDMA

5 Wireless LANs: typical characteristics Applications: data-centric Topology: centralized or ad hoc Media access control: distributed Frequency use: time division Bandwidth: high Physical layer: spread spectrum or OFDM What are the similarities and differences with cellular?

6 Wireless LAN application characteristics

7 Wireless LAN topologies Infrastructure: Access point (AP) serves as point of connection for subscriber stations (SS) Subscriber to subscriber communication via AP Difference with cellular BS: AP does NOT control resource allocation AP does not manage mobility

8 Wireless LAN infrastructure topology AP Internet AP Hand offs are NOT normally supported SS SS SS

9 Unlicensed spectrum: Wi-Fi (Wi-Fi): authorized for use at 2.4GHz and 5.8GHz High bandwidth: up to 54 Mbps Short range Line of sight A few thousand feet, at most Well-suited for data (voice is problematic) Not designed for people on the move!

10 Wi-Fi based Internet access Works well indoors, urban areas High-gain antennas used to extend range outdoors Can be cost-competitive where user densities are not too low Services in the range of 250 kbps 500kbps for $40-$60/month Line of sight is necessary Subscriber equipment relatively inexpensive (~$100-$300)

11 Use of Wi-Fi for fixed Internet access in rural areas

12

13 A war drive of Bozeman 41 WiFi access points Congestion may be the downfall of Wi-Fi and other approaches that use unlicensed spectrum

14 What about Havre?

15 What else is there? WiMAX (802.16) Standards being completed Wi-Fi on steroids? Longer range: up to 30 miles Higher data rates: up to 60 Mbps Mobility friendly? Wait for Products entering the market: Intel and others

16 Early applications of WiMAXin Montana!! Point-to-point Dragonwave AirPair - Incremental Mbps - 18,23 and 24GHz - Highly stable

17 Current deployments of point-tomultipoint in Montana Aperto Packetwave - Highly stable - Excellent throughput - Still targeting businesses - Costs need to fall to make this practical for residential use

18 Forecast of WiMAX growth But will WiMAX cover rural areas?

19 Unlicensed operation - Part 15 - radio frequency devices Provides For Operation of Low Power Transmitters Without a User License Examples: Garage door openers; cordless telephones; keyless entry systems; radio controlled toys; anti-pilferage systems, wireless data networks (LANs, PANs, etc.) Widely used for Internet access services Vulnerable to interference!!

20 Licensed radio services Licensed Radio Services Have Interference Protection Flexible Rules: Licensee May Choose Service/Technology Examples: Cellular; PCS; MMDS; LMDS, etc. Equipment Must Meet Basic Technical Standards Equipment Authorization is Required Not widely used for Internet access services

21 Sioux Valley, SD: using licensed MMDS spectrum for internet access services MMDS (TV service) Sioux Falls, SD in Two-way wireless FCC Developmental license for internet in Initial data equipment was limited, experimental and expensive. FCC two-way engineering and licensing was very challenging. Cover a large (35 mile radius) rural area, 1000 users $45/Mo. + $200 installation

22 Sioux Valley Wireless: using licensed spectrum for high-speed internet access in rural South Dakota

23 Sioux Valley - subscriber density 35 mile radius, some uses are widely scattered

24 Multi-point wireless access: pros and cons Works well at medium density Need line of sight paths Attractions of unlicensed spectrum Low equipment costs Easy to get started Problem of unlicensed spectrum: interference Licensed spectrum Need a license! Less equipment options (so far..)

25 Is there a solution to this problem? I Love the convenience, but the roaming charges are killing me!

26 Globalstar satellite voice and data services

27 Two-way Internet via satellite

28 DIRECWAY satellite Internet access Asymmetric, limited bandwidth Users Downstream Upstream 1/household Up to500 kbps Up to 50 kbps Equipment $600 purchase Monthly service fee $60

29 New high-capacity spot-beam satellite designed for Internet services

30 Satellite-based Internet access pricing WildBlue example

31 Satellite-based Internet access: pros and cons Good fit for rural and remote sites Bandwidth (capacity) limits of satellites Long time delay (0.25 sec) due to geosynchronous orbit High costs for satellites Costs of end user equipment However, satellite links will work where other types of Internet access are not available

32 The cellular radio concept: frequency reuse to increase capacity

33 Cellular networks- is there enough capacity for high-speed Internet service? Speed bps 100 M 10 M 1 M 100 K BT = Bluetooth H2 = Hiperlan 2 PDC = Personal Digital Cellular H b 5.5/11 Mb PBCC BT WCDMA EDGE cdmaone GPRS1X EV-DC, 3X??? 10 K AMPS G PDC cdma2000 GSM 1X TDMA cdmaone G 2.5G 3G 3.5G 4G

34 VerizonWireless coverage in Montana: Digital technology deployed only in the dense population centers Equipment Service Availability Pricing Glossary of Terms RED: Digital voice (2G)+limited data (50 kbps)

35 Cellular for Internet access: pros and cons New cellular technologies are more data friendly Roll out and coverage in rural areas is slow and poor Bandwidth is a premium on cellular systems Prices will remain high Will never reach the high speeds of wired connections

36 Internet access in Montana: summing it up Dial up: Works almost everywhere Low speed: can we endure the waits? DSL: Becoming mature Good for higher density areas Range limitations Cable: Popular in urban areas Low cable penetration in Montana

37 Internet access in Montana: summing it up (II) Fiber to the X: Still expensive Beginning to appear in new, up-scale developments Powerline carrier: Early stage of deployment Range may limit use in rural areas Wireless: Comes in many flavors Standards are lowering costs Some range limits, but appealing

38 Internet access in Montana: summing it up (III) Cellular: best suited for mobile use New generations slowly reaching Montana Capacity limits and high costs Satellite: good fit for rural and remote areas New generation of satellite systems shows promise Still have to contend with earth-space delay Ad hoc/mesh: Intriguing variant on wireless

39 So why not more broadband service in Montana? Is there sufficient demand? High capital costs? Difficult environmental factors? Lack of interest by service providers? Unattractive business case? Maybe Montana is a niche yet to be discovered!