High-speed Internet Access: Wireless and WiFi Richard S. Wolff, Ph. D Montana State University Department of Electrical and Computer Engineering. rwolff@montana.edu 406 994 7172
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 802.11 H2 802.11b 5.5/11 Mb 802.11 PBCC BT WCDMA EDGE cdmaone GPRS1X EV-DC, 3X??? 10 K AMPS 1985 1G PDC cdma2000 GSM 1X TDMA cdmaone 1990 2000 2010 2G 2.5G 3G 3.5G 4G
Bandwidth available is inversely proportional to range
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
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?
Wireless LAN application characteristics
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
Wireless LAN infrastructure topology AP Internet AP Hand offs are NOT normally supported SS SS SS
Unlicensed spectrum: Wi-Fi 802.11 (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!
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)
Use of Wi-Fi for fixed Internet access in rural areas
A war drive of Bozeman 41 WiFi access points Congestion may be the downfall of Wi-Fi and other approaches that use unlicensed spectrum
What about Havre?
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 802.20 Products entering the market: Intel and others
Early applications of WiMAXin Montana!! Point-to-point Dragonwave AirPair - Incremental Mbps - 18,23 and 24GHz - Highly stable
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
Forecast of WiMAX growth But will WiMAX cover rural areas?
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!!
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
Sioux Valley, SD: using licensed MMDS spectrum for internet access services MMDS (TV service) Sioux Falls, SD in 1996. Two-way wireless FCC Developmental license for internet in 1998. 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
Sioux Valley Wireless: using licensed spectrum for high-speed internet access in rural South Dakota
Sioux Valley - subscriber density 35 mile radius, some uses are widely scattered
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..)
Is there a solution to this problem? I Love the convenience, but the roaming charges are killing me!
Globalstar satellite voice and data services http://www.globalstarusa.com/en/
Two-way Internet via satellite
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
New high-capacity spot-beam satellite designed for Internet services
Satellite-based Internet access pricing WildBlue example
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
The cellular radio concept: frequency reuse to increase capacity
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 802.11 H2 802.11b 5.5/11 Mb 802.11 PBCC BT WCDMA EDGE cdmaone GPRS1X EV-DC, 3X??? 10 K AMPS 1985 1G PDC cdma2000 GSM 1X TDMA cdmaone 1990 2000 2010 2G 2.5G 3G 3.5G 4G
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)
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
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
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
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
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!