http://www.wimaxforum.org/technology/downloads/WiMAX_to_Bridge_the_Digitaldivide.pdf

• While the gap is smaller, many rural areas still have no ICT connection

http://www.wimaxforum.org/technology/downloads/WiMAX_to_Bridge_the_Digitaldivide.pdf

WiMAX: key points

• LOS range: 50km

• NLOS range: 8km

• Cost: Goal of $100 CPE (customer premise equipment)

• NLOS allows indoor CPE installation

• Standardization

http://www.wimaxforum.org/technology/downloads/WiMAXNLOSgeneral-versionaug04.pdf

Combining several techniques

• Subchannelization • Directional antennas • Diversity schemes • Adaptive modulation

– Flex to actual fading conditions, so don’t have to budget for worst-case

• Error correction • Power control

– Base station tells CPE how much transmit power is needed, so don’t need to budget for worst-case

• http://www.wimaxforum.org/technology/downloads/WiMAXNLOSgeneral-versionaug04.pdf

• Subscriber Units• WiMAX subscriber units are available in both indoor and outdoor

versions from several manufacturers. Self-install indoor units are convenient, but radio losses mean that the subscriber must be significantly closer to the WiMAX base station than with professionally installed external units. As such, indoor installed units require a much higher infrastructure investment as well as operational cost (site lease, backhaul, maintenance) due to the high number of base stations required to cover a given area. Indoor units are comparable in size to a cable modem or DSL modem. Outdoor units are roughly the size of a textbook, and their installation is comparable to a residential satellite dish. (from wikipedia.com)

How 802.16 is different from 802.11

• MAC layer: scheduling vs contention

• Range: kilometers vs 100s of meters

• Spectrum Allocation/licensing

• Wikipedia.com

Namibia, N$500 = $72

• http://www.mweb.com.na/index.php?fArticleId=1483811

VSAT Advantages• Availability: VSAT services can be deployed anywhere having a

clear view of the Clarke Belt • Diversity: VSAT provides a wireless link completely independent of

the local terrestrial/wireline infrastructure - especially important for backup or disaster recovery services

• Deployability: VSAT services can be deployed in hours or even minutes (with auto-acquisition antennas)

• Homogenity: VSAT enables customers to get the same speeds and SLAs at all locations across their entire network regardless of location

• Acceleration: Most modern VSAT systems use onboard acceleration of protocols such as TCP ("spoofing" of acknowledgement packets) and HTTP (pre-fetching of recognized HTTP objects); this delivers high-quality Internet performance regardless of latency (see below)

• Multicast: Most current VSAT systems use a broadcast download scheme (such as DVB-S) which enables them to deliver the same content to tens or thousands of locations simultaneously at no additional cost

• Security: Corporate-grade VSAT networks are private layer-2 networks over the air

Wikipedia.com

VSAT disadvantages• Latency: Since they relay signals off a satellite in geosynchronous

orbit 22,300 miles above the Earth, VSAT links are subject to a minimum latency of approximately 500 milliseconds round-trip. This makes them a poor choice for "chatty" protocols or applications such as online gaming

• Encryption: The acceleration schemes used by most VSAT systems rely upon the ability to see a packet's source/destination and contents; packets encrypted via VPN defeat this acceleration and perform slower than other network traffic

• Environmental concerns: VSATs are subject to signal attenuation due to weather ("rain fade"); the effect is typically far less than that experienced by one-way TV systems (such as DirecTV or DISH Network) that use smaller dishes, but is still a function of antenna size and transmitter power and frequency band

• Installation: VSAT services require an outdoor antenna installation with a clear view of the southern sky; this makes installation in skyscraper urban environments or locations where a customer does not have "roof rights" problematic

Wikipedia.com

VSAT training

• Fees for participants based in Nigeria: • NGN 50 000 per person. 

NGN 48 000 per person for two per company.NGN 45 000 per person for three to nine people per company.

  ($1 = NGN 132, NGN50000 = $410)• Fees for International Participants (participants

attending from outside Nigeria):US$ 550 per person. US$ 530 per person for two per company.US$ 520 per person for three to nine people per company.

• http://www.jidaw.com/vsattrain/index.html

The satellite dish

• http://www.jidaw.com/vsattrain/index.html

• minimum US$1800-2000 per mbps per month for satellite

• SAT3: US$7,000 – US$15,000 (SAT3/WASC/SAFE Consortium is an international fibre that goes from Portugal to South Africa and out across the Indian Ocean to Asia)

http://fibreforafrica.net/main.shtml?x=4051583&als[MYALIAS6]=Satellite%20vs%20fibre:%20different%20costs%20for%20different%20things&als[select]=4051582

• Rural Satellite VSAT Market in Middle East and Africa

• 2002 : 7,000 • 2006 : 60,000

http://www.tmcnet.com/usubmit/2007/04/25/2553510.htm