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Wireless Solutions in Developing Countries
Lessons learned in Latvia and around the World
Guntis Barzdins ([email protected]) Taide Network and University of Latvia (Latnet)John Tully ([email protected]) MikroTikls SIA and LatnetArnis Riekstins ([email protected]) MikroTikls SIA and Polymer Mechanics Institute
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
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 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 staffEquipment supplied or Installation consulted
GHANA
S.KOREA
PERU
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 Latvia11Mbps 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
Wireless isHalf-duplex & Multi-point
but
100x faster
What is a Wireless Internet access?
Equipment: regular 2.4GHzLicense-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
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
Vendor Product Positive Negative
Aironet PC4800($800)
up to200mW outputpower, hardware errorcorrection
Higher price
LucentTechnologies
ISATurbo($500)
Low cost Only 20mW output power,short range
BreezCom BreezeLink($1000)
Eexternal unit with twoantenna connectors.Telephone line support
Degraded performance in“noisy” city environmentdue to FH radio
ourpreference
Antennas & Cables & Connectors
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 User site:24dBi
directional grid antenna
Central site:5.5-8dBi or more Omni-directional antenna
Lightning protection! Snow cover in arctic
regions oursuggestion
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!oursuggestion
Distance calculator:• cable length• antenna gain• speed• power
http://www.ltn.lv/~guntis/smarp/
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
ourpreference
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
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
SmartARP configuration
10.1.1.0 255.255.255.0 local10.1.2.0 255.255.255.0 forward 00:01:3a:4c:1210.1.3.0 255.255.255.0 forward 00:73:18:a5:6210.1.4.0 255.255.255.0 forward 00:0c:63:52:7a
Configuration file of SmartARP server A:
MAC addressof smartARP
server B
Ranges of IP addressesassigned client networks
Free SmartARP for Win95 and LINUX at:http://www.ltn.lv/~guntis/smarp/
New!
What to do with ARP requests
MAC addressof smartARP
server C
MAC addressof smartARP
server D
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
Traditional IP routerIP range Next Hop IP
192.12.76.0/24 199.1.2.13 194.42.32./28 193.5.77.1198.4.15.0/24 199.1.2.13
Routing table ARP table
IP addr MAC addr
199.1.2.13 00:14:0c:76:82 193.5.77.1 00:0c:21:44:15
Bridge with IP filter, no STP
IP forwarding table
IP range Next Hop MAC
192.12.76.0/24 00:14:0c:76:82 194.42.32./28 00:0c:21:44:15198.4.15.0/24 00:14:0c:76:82
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
TREND:
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
