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Wireless Solutions in Developing Countries

Wireless Solutions in Developing Countries. Lessons learned in Latvia and around the World. Guntis Barzdins (guntis@latnet.lv) Taide Network and University of Latvia (Latnet) John Tully (tully@mt.lv) MikroTikls SIA and Latnet Arnis Riekstins (rieks@mt.lv)

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Wireless Solutions in Developing Countries

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  1. Wireless Solutions in Developing Countries Lessons learned in Latvia and around the World Guntis Barzdins (guntis@latnet.lv)Taide Network and University of Latvia (Latnet) John Tully (tully@mt.lv) MikroTikls SIA and Latnet Arnis Riekstins (rieks@mt.lv) MikroTikls SIA and Polymer Mechanics Institute

  2. Agenda • Latnet and MikroTikls - who are we? • Wireless Internet in Latvia and elsewhere • Elements of wireless Internet access • Wireless Components • Software • Issues to Consider: Traditional and New solutions

  3. Short history of Wireless Internet in Latvia • 1993: first 915MHz WaveLan link in Riga • 1994-1996: Latnet wireless network extended • 1996: paper “Wireless Internet Access in Latvia” published on the Internet • 1996: MikroTikls company founded • 1996: By contract with Taide Satellite, MikroTikls installs first 2.4GHz wireless network in Moldova • 1996-present: queries from around the World

  4. Current Activities • Buildings connected to the Internet by 2.4GHz wireless links in Riga : • 1997 - More than 100 • 1998 - More than 200 • 1999 (May) - More than 300 • Also 15 regional cities in Latvia have wireless Internet access • Wireless installations & consulting worldwide • Development of new wireless solutions

  5. On-site installation by our staff Equipment supplied or Installation consulted Latnet and MikroTikls assisted Wireless installations since 1993 S.KOREA GHANA PERU

  6. Actual reason for Wireless Wireless Internet is cheaper than Leased line Internet access Other reasons • leased lines not available • low quality dial-up lines • national telecom monopoly • quick installation • better throughput (up to 11Mb/s)

  7. 11Mbps Wireless Internet access Installation PC router $450 Wireless card $800 Antenna&cable $250 Monthly fee wireless link $0 Internet $300 128Kbps Leased line Internet access Installation Leased line installation $900 Cisco router $1400 Monthly fee leased line $250 Internet $300 Example from Latvia Wireless isHalf-duplex & Multi-point but100x faster

  8. What is a Wireless Internet access?

  9. Central site omni-directional antenna wireless bridge or access point increased performance increased reliability User site high-gain directional antenna PC router with wireless card router separates user LAN(firewall) back-up routing through dial-up cheaper than WirelessBridge + Cisco router Equipment: regular 2.4GHzLicense-fee wireless LAN

  10. How to make Wireless link cheap but reliable? • Components are cheap, integrated solutions are expensive and inflexible. Do it yourself: • Which wireless LAN vendor and product to choose? Which parameters matter? • What antennas and cables will work the best? • Which PC routing software to use? What are known problems with each of them? • What communication distances are realistic and what influences that? Will power amplifier extend the range?

  11. All listed devices support up to 11 Mbps, operate in 2.4GHz license-free ISM band, and use Spread Spectrum technology IEEE 802.11 compliance is optional - in “long range” applications top performance can be achieved only with same vendor equipment Wireless LAN Card Vendors ourpreference

  12. Cables L-loss cable designed for 2.4GHz (1dB loss per 1 meter is a ‘good value’) Use short cable! (30m max) Connectors Because of FCC regulations, cards have custom connectors - hard to get, expensive Water in connector is the most frequent problem. Apply HERMETIC isolation to connectors ALWAYS! Antennas & Cables & Connectors • Antennas • User site:24dBi directional grid antenna • Central site:5.5-8dBi or more Omni-directional antenna • Lightning protection! • Snow cover in arctic regions oursuggestion

  13. Environmental Aspects • Direct line of sight required • Rain and snow has no influence on the link • Distances: • 12km radius around the Access Point for point-to-multipoint connections (4km with ETSI compliant antennas) • 40km between two nodes with directional antennas for point-to-point links (10km with ETSI compliant antennas) • Amplifiers amplify also noise - avoid them! • Distance calculator: • cable length • antenna gain • speed • power • http://www.ltn.lv/~guntis/smarp/ oursuggestion

  14. PC routing software - DOS and Windows • Windows NT (too bulky) • Windows 95/98 cannot route! • DOS based IP routers (up to 2Mbps only!) • PCroute has no remote, VLSM (free) • IProute by Dave Mischler (license $50) • KA9Q, JNOS, TNOS,... (free, but slow and unreliable) ourpreference

  15. PC Routing Software - UNIX • Linux Router Project • good, but few wireless cards have working Linux drivers • FreeBSD based router - same problem • MicroTik wireless router software(Linux based) • supports most Wireless and ordinary NICs • remote management via telnet and http • wireless network diagnostics & testing options • commercial version $300 ourpreference

  16. New! Use Aironet Bridge as a Router • Price: PC+WirelessCard=WirelessBridge • Bridge works at -20C: can be mounted at antenna outdoors (increased range) • Bridge acts as a repeater: micro-cells • Bridge can be configured to: • Forward all unicast frames • Discard all multicast/broadcast frames • Filter frames on additional header fields • Server-based ARP needed: SmartARP

  17. New! SmartARP configuration Free SmartARP for Win95 and LINUX at: http://www.ltn.lv/~guntis/smarp/ MAC addressof smartARP server B Configuration file of SmartARP server A: 10.1.1.0 255.255.255.0 local 10.1.2.0 255.255.255.0 forward 00:01:3a:4c:12 10.1.3.0 255.255.255.0 forward 00:73:18:a5:62 10.1.4.0 255.255.255.0 forward 00:0c:63:52:7a MAC addressof smartARP server C MAC addressof smartARP server D Ranges of IP addressesassigned client networks What to do with ARP requests

  18. Traditional IP router Bridge with IP filter, no STP IP range Next Hop IP 192.12.76.0/24 199.1.2.13 194.42.32./28 193.5.77.1 198.4.15.0/24 199.1.2.13 IP addr MAC addr 199.1.2.13 00:14:0c:76:82 193.5.77.1 00:0c:21:44:15 IP range Next Hop MAC 192.12.76.0/24 00:14:0c:76:82 194.42.32./28 00:0c:21:44:15 198.4.15.0/24 00:14:0c:76:82 Routing table ARP table IP forwarding table Future • Routing and VLANs complex to manage with 100s of permanently connected customers (with backup links) • Max auto-configuration is needed: Bridging with IP prefix filter vs. Routing • Substitute for inefficient Spanning Tree Protocol (STP) used by Bridges

  19. Conclusion: Preferred Solution • Aironet 11Mbps Turbo DS • Bridge BR500-E or AP4800 (central site) • PCrouter with ISA or PCI4800 (client) • Routing software • IPRoute ($50) • MikroTik router software ($300) • SmartARP software (free) • Quality Cables, Antennas, Connectors • Up to 20 clients per cell of 7-12km radius(in city environment use 1-2km micro-cells + microwave or fiber backbone) TREND: Use wires and same software to share Internet connection with neighbors

  20. References • Slides available at:http://www.ltn.lv/~guntis/smarp/ • Latnet (operates wireless network in Latvia)http://www.latnet.lv • MikroTikls (wireless hardware & software)http://www.mt.lv • Taide Network (satellite communications)http://www.taide.net

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