Wireless Networking in Nigeria By Sunday A Folayan

Wireless Networking in Nigeria By – Sunday A Folayan General Data Engineering Services Ltd, Ibadan

General Data Eng. Services Started SKANNET in October 1996 with: • One laptop • Two phone lines • 3 dial-up clients by Nov 1. 1996 • Capital of N 200, 000. ($8, 000) ($1=N 25 then)

SKANNET …May 2001: • 2000 Turnover > N 50 m ($420, 000) • Fifty (50) dial-up phone lines • 5, 241 dial-up clients in Apr. 2001 • Over N 30 m ($250, 000) Fixed assets ($1=N 125 Now)

Why use wireless? z Inability to obtain more lines from the PTT z Available phone lines barely do 28. 8 kbps z Clients’ Demand for bandwidth greater than what the dial-up lines can support z Lack of alternative technology such as DSL or ISDN

Design Choices The cost of getting equipment manufactured to specification is beyond the means of most African operators. We thus have to choose among products in the market. z Physical Layer: Infra-Red (IR) VS Radio Frequency (RF) z Technology: Frequency Hopping VS Direct Sequence z Frequency: 902 – 928 Mhz, 2. 4 -2. 483 Ghz, 5. 15 – 5. 875 GHz z Access Method: TDMA VS CSMA z Topology: Peer to Peer VS Base Station Access

SKANNET chose Cisco Aironet Products z Operates in the 2. 4 GHz ISM band z Uses the Direct Sequence method z Up to 11 Mbps data rate z Up to 25 Km (? ) Radius z Wired Equivalence Privacy

Equipment Sources Equipment sources are mixed z. Radio: Provantage - www. provantage. com z. Antenna: Mikrotik - www. mikrotik. lv

Product Options Wireless Bridge Workgroup Bridge PCI Card ISA Card PCMCIA Card

Antennas 15 d. B Omni Directional base station antenna and 24 d. B Directional Customer service antenna

Omni-directional Antenna is Elevated on a 120 ft Mast

Indoor Equipment Fits neatly into a 42 U cabinet. Help Desk is in the foreground.

Service Options Equipment 1. Outright Purchase 2. Hire Purchase agreement with end-time ownership 3. Lease agreement. No end time ownership Bandwidth 1. Pay-Per-Use bandwidth limited Access 2. 24 x 7 Bandwidth limited Access Bandwidth is sold Differentially (Internet/Intranet ) 64 K/8 K is N 30, 000 ($240) per month.

Subscription

Bandwidth Management z Solution: Hardware/Software combo from Emerging Technologies Inc. www. etinc. com z Major Advantage: Management of bandwidth by MAC addresses, apart from IP Number. Has 5 of 100 Base T ports that can be individually limited. z Differential Bandwidth: Setting Internet Access bandwidth much lower than Intranet Access

Metering and Billing 1. The bandwidth manager has MRTG-like graphing utility, for examining the utilization pattern of each subscriber, either daily, week or monthly. 2. Using a simple PERL script running on the bandwidth manager, bandwidth utilization statistics are extracted for each subscriber 3. Summary of utilization is written to a my. SQL database, which is read by the billing software 4. Another PERL script on the Bandwidth manager limits Expired accounts to 1 kbps.

Problems encountered Excessive RF Cable Length leads to signal attenuation Solution: Keep RF cable to less than 15 meters. If length will be more than 15 meters, then mount Radio in a weatherproof case, close to the antenna and use a short RF cable. Ferry the signal from the Radio, using Ethernet cable to the hub or router. Ethernet cable can be as long as 300 ft.

Problems encountered Bulky power system and cabling to Weatherproof case Solution: Use pairs 4/5 and 7/8 of the Ethernet cable to carry 18 V DC required to power the Radio. Power drop is not a problem, since Cisco Aironet radios operate from 12 V to 18 V.

Problems encountered Costant power to run the Repeater stations Solution: Use a mixture of Solar and Wind power where there is erratic public utility supply

Further reading … Wireless Local Area Network (LAN) tutorial. http: //www. wirelesslan. com Wireless LAN design alternatives by David F. Bantz and Frederic J. Bauchot. http: //www. cs. berkeley. edu/~adj/cs 294 -1. s 98/wireless_lan/sld 001. htm How to start a Wireless ISP http: //www. mikrotik. lv/3 index. html#q 1 Thank You!