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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

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

  • 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
short history of wireless internet in latvia
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
current activities
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
latnet and mikrotikls assisted wireless installations since 1993

On-site installation by our staff

Equipment supplied or Installation consulted

Latnet and MikroTikls assisted Wireless installations since 1993




actual reason for wireless
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)
example from latvia
11Mbps Wireless Internet access


PC router $450

Wireless card $800

Antenna&cable $250

Monthly fee

wireless link $0

Internet $300

128Kbps Leased line Internet access


Leased line installation $900

Cisco router $1400

Monthly fee

leased line $250

Internet $300

Example from Latvia

Wireless isHalf-duplex & Multi-point

but100x faster

equipment regular 2 4ghz license fee wireless lan
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
how to make wireless link cheap but reliable
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?
wireless lan card vendors
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


antennas cables connectors

L-loss cable designed for 2.4GHz (1dB loss per 1 meter is a ‘good value’)

Use short cable! (30m max)


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


environmental aspects
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/


pc routing software dos and windows
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)


pc routing software unix
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


use aironet bridge as a router


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
smartarp configuration


SmartARP configuration

Free SmartARP for Win95 and LINUX at:


MAC addressof smartARP server B

Configuration file of SmartARP server A: local forward 00:01:3a:4c:12 forward 00:73:18:a5:62 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


Traditional IP router

Bridge with IP filter, no STP

IP range Next Hop IP 194.42.32./28

IP addr MAC addr 00:14:0c:76:82 00:0c:21:44:15

IP range Next Hop MAC 00:14:0c:76:82 194.42.32./28 00:0c:21:44:15 00:14:0c:76:82

Routing table

ARP table

IP forwarding table

  • 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
conclusion preferred solution
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)


Use wires and same software to share Internet connection with neighbors

  • 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