I-O Wireless WBS11 User manual

LAN to LAN Bridge
User’s Guide
Models WBS11 & WBC11
Version 1.0 October 2001

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Copyright and Trademarks
This document contains materials protected by copyright. All rights are reserved.
No part of this manual may be reproduced or transmitted in any form, by any
means or for any purpose without expressed written consent of its authors. The
authors reserve the right to revise this publication and to make changes to any or
all parts of this manual at any time, without obligation to notify any person or
entity of such revisions or changes.
Product names appearing in this document are mentioned for identification
purposes only. I-O Wireless™ is a trademark of I-O Corporation. AirLock™ and
ASBF™ are trademarks of No Wires Needed. Windows® is a registered
trademark of Microsoft Corporation. All other products referenced are
trademarks or registered trademarks of their respective companies.

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TABLE OF CONTENTS
1 INTRODUCTION ..............................................................................................4
1.1 Product Introduction ...................................................................................4
1.2 What is Included .........................................................................................5
1.3 Installation Overview...................................................................................6
1.4 Hints for a Successful Installation...............................................................6
2 HARDWARE INSTALLATION...........................................................................7
2.1 The Antenna Installation .............................................................................8
2.1.1 Radiation Diagram...............................................................................8
2.1.2 Multi path.............................................................................................9
2.1.4 Line of sight.......................................................................................12
2.1.5 The link budget..................................................................................13
2.1.6 Mechanical Installation of the Antenna..............................................15
2.1.7 Antenna Installation Hints..................................................................16
2.1.8 Lighting protection .............................................................................17
2.2 Basic Alignment of the Antenna................................................................18
2.3 Configuration of the Bridge Units..............................................................21
2.4 Fine Tuning of the Bridge Link..................................................................24
2.5 Installing the Bridge Unit...........................................................................26
3 BRIDGE CONFIGURATION PROGRAM........................................................27
3.1 Installation ................................................................................................28
3.2 The Network Configuration .......................................................................30
3.3 The Device Settings..................................................................................32
3.4 Resetting the Bridge .................................................................................35
4 TROUBLESHOOTING....................................................................................36
5 SPECIFICATIONS ..........................................................................................37
5.1 LAN to LAN Bridge ...................................................................................37
5.2 SLH 10 Helix Antenna .............................................................................39
5.3 SLH 12 Stub Loaded Helix Antenna ........................................................40
5.4 Power Supply Specifications ....................................................................41
5.5 Cable Specifications .................................................................................42
GLOSSARY ........................................................................................................44
AGENCY COMPLIANCE NOTICES ...................................................................48
HARDWARE WARRANTY .................................................................................51
SOFTWARE LICENSE AGREEMENT................................................................52
PRODUCT SUPPORT AND WARRANTY ADMINISTRATION POLICY ............54

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1 Introduction
Thank you for purchasing the I-O Wireless LAN to LAN Bridge. This manual will
assist you with the installation and use of the bridge.
1.1 Product Introduction
A wireless LAN to LAN bridge is used to create either a point-to-point or a point-
to-multipoint link between two or more local area networks.
Due to the complexity of installing a wireless bridge, always make sure a
professional installs the bridge link. A professional installer not only provides you
with an optimized link; he also supplies you with a professional mechanical
installation.
The professional installer covers the following areas:
•Network link installation
•Mechanical installation
•Weather resistant installation
•Lightning proof installation
By covering all these areas the installer will provide you with a link that has the
highest possible uptime. He will also take away every possible chance of
damaging your network.
In order to establish a link between two or more networks, it is essential that the
antenna of the server and the antenna of the client be in line of sight. Chapter 2
will define line of sight in depth and explains the installation of the antennas.
Figure 1.1:The bridge, the connectors and indicators

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Figure 1.2: The back panel of the wireless bridge
HINT: Before you start, write down the MAC addresses of all bridge units. These
addresses are located on the backside of the unit and are difficult to access after
installation.
1.2 What is Included
The package you have received contains the following items:
•Bridge server unit and/or Bridge client unit
•Antenna adapter cable
•Power supply
•CD-ROM containing the bridge configuration software and user’s guide
•Antenna (if ordered)
It is the customer’s responsibility to perform site surveys and supply all mounting
hardware, antenna cabling, lightening protection devices, etc. that may be
required to effect a secure, reliable and successful installation.

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1.3 Installation Overview
The steps involved in installing the I-O Wireless LAN to LAN Bridge are:
1. Review this user’s guide – pay specific attention to Chapter 2.
2. Determining the location for the antennas and bridge units.
3. Determining the availability of power and access to the Ethernet LAN.
4. Installing the antennas and running the antenna cable to the bridge units.
5. Connecting the bridge units to the antenna cable, Ethernet LAN and
power.
6. Installing the bridge configuration software.
7. Configuring the bridge server unit.
8. Configuring the bridge client unit(s).
9. Tuning the antenna alignment.
10. Fine tune the bridge communication values (if needed)
1.4 Hints for a Successful Installation
•Have your wireless bridge installed by a professional.
•Thoroughly test all antenna and network cables before connecting the
bridges.
•Make certain to keep the antenna cable as short as possible and use “low
noise” cable such as LMR-400.
•Make certain that the SSID is entered exactly the same in all bridge units.
•Make certain that the IP address, sub-net masks and gateway address
coincide with your network addressing plan.
This user’s guide is designed to provide you with information necessary to
accomplish a successful installation of your I-O Wireless LAN to LAN Bridges.

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2 Hardware Installation
This chapter describes:
•The installation of the antennas
•The installation and configuration of the bridge units
•Connecting the antennas to the bridge units
Before starting the installation, some understanding of antennas and their
behavior is necessary. In the following chapter the most important characteristics
are explained. If you are not familiar with antenna technology please take a few
minutes to read this information and understand more about antenna installation.
Note: Detached antennas, whether installed indoors or out, should be installed
ONLY by experienced antenna installation professionals who are familiar with
local building and safety codes and, wherever applicable, are licensed by the
appropriate government regulatory authorities.
Failure to do so may void the I-O Product Warranty and may expose the end
user to legal and financial liabilities. I-O and its resellers or distributors are not
liable for injury, damage or violation of government regulations associated with
the installation of detached antennas.
It is the responsibility of the professional installer to ensure that when using
antennas in the United States (or where FCC rules apply), only these antennas
mentioned in this manual are used. The use of any antenna other than those
listed is expressly forbidden in accordance with the FCC rules CFR47 part
15.204.

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2.1 The Antenna Installation
2.1.1 Radiation Diagram
The bridge units are supplied with a choice of two different antennas.
The type of antenna used depends on the type of link (point-to-point or point-to-
multipoint) and the required range. All antennas are directional by nature; they
cannot be made to radiate uniformly in all directions. Therefore, antennas are
designed with controlled properties to guide available RF energy in the desired
direction. This directivity multiplied by antenna efficiency is gain. Gain is
expressed in decibels relative to a hypothetical isotropic source that radiates
uniformly over a spherical surface. Figure 1.1 displays the radiation pattern of an
antenna with the gain referenced to an equivalent isotropic source. The gain of
the isotropic source is the unity or zero decibels. Depending on the directive
behavior of an antenna and the site requirements, the type of antenna is chosen.
This diagram displays the radiation power versus the direction. Figure 2.1
displays the radiation diagram of a Stub Loaded Helix (SLH) antenna.
Figure 2.1 The radiation diagram of a Stub Loaded Helix (SLH) antenna
The more directive an antenna is, the more gain an antenna has in one specific
direction. Installing an omni directional antenna for a point-to-point link is
inefficient, unless the range between the two antennas is short. In such a case
the choice for an omni-directional antenna is a purely economical.
-30-30 -2 0-20 -10-10

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2.1.2 Multi path
2.1.2.1 Polarization
Direct Sequence technology is more sensitive for multi-path effects than the
traditional Frequency Hopping. Multi-path effects can be explained as coherent
signals (signals from the same source) arriving at the antenna at different times
due to the difference in path length. Several signals from the same source
meeting at the receiving antenna can arrive in phase, out of phase or in between.
When the level of each incoming signal is included, the effects can be any of the
following:
Level Phase Result
Equal In Strong reception
Unequal In Good results
Equal Out Possible loss of
reception
Random Random Variable levels
The conductivity of the reflector and polarization of the wave before reflection
primarily affect the level of the signal. Horizontal polarized signals, which are
parallel to the reflecting surface, will reflect almost totally without appreciable loss
at the point of bounce.
Vertically polarized signals are perpendicular to the reflecting surface, and will
either be totally reflected from a conductor, or will propagate along the surface
(depending on the angle of the arriving energy). Since radiated waves penetrate
loose materials, energy can be lost to heat generation.
Circularly polarized signals are composed of a combination of vertically and
horizontally polarized signal which are in phase quadrature (offset 90°) with each
other. Depending on their phasing, the sense of circularly polarized signals are
described as right-handed or left-handed. Circularly polarized signals have the
unique property that the sense changes upon reflection. Thus, a right-hand
circularly polarized signal becomes left-handed upon reflection. A circularly
polarized antenna will only respond to one sense, either right or left, depending
on its design.
By using circular polarization, the effect of multipath interference can be greatly
reduced. This makes setting up wireless links easier and more reliable than
when using horizontal or vertical polarization. I-O bridge products use circularly
polarized antennas exclusively.
2.1.2.2 Refraction

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The velocity of RF energy is slower in dielectric materials that are denser than
dry air. The result is refraction, or the change of direction of propagation as radio
waves pass through these materials. The time spent in the denser material
controls the degree of refraction and the resulting direction of the emerging wave.
2.1.2.3 Diffraction
Perfect shadows that are cast by RF-opaque structures or objects are rare at
wireless system frequencies. Because of diffraction, energy scatters at the edges
of the obstruction. Diffraction is more pronounced in sharp or knife edged
corners. According to field theory, edges cause secondary radiation when
illuminated. This is generally independent of polarization when the scatterer is
much longer than the impinging signal’s wavelength.
Diffraction forms a fuzzy signal source at the edges, which tends to fill in the
shadowed regions. The signal levels are low but often usable. These edges can
be corners of a building, window frames or large vehicles. Diffraction also figures
significantly in scattering at hilltops lying in the propagation path.
2.1.2.4 Locating the Antenna
Free space radiation patterns are the baseline performance criteria before
installation in the real world environment. Since sites are located on rooftops, or
on the side of buildings; many opportunities exist for interference from chimneys,
walls, masts, towers and other antennas. Although it is difficult to predict level
changes you can take steps to minimize pattern distortion.
Obstructions are either conducting or non-conducting. Conducting objects create
the most severe disturbances. Those near the resonant length of the antennas,
such as other antennas, behave as the parasitic elements of an uncontrolled
array, producing random nulls and lobes. Larger conducting structures causes
severe shadowing. The closer the spacing, the larger the shadow.
Locate the antenna as far from other conducting objects as feasible. In
particular, avoid placing the antenna where obstructions are within the view of
the antenna main beam. For highly directional antennas, the presence of
conductive objects in the rear lobe of the antenna is not critical.

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2.1.3 Free space losses
Spreading is the principal contributor to signal loss for line of sight propagation.
As a signal radiates it spreads or expands into a spherical surface. The available
RF power is distributed over this surface and weakens with increasing range.
The signal is reduced by 6 dB for every doubling of distance from the source.
The loss path between the source radiators with spherical patterns is computed
using the following equation:
Lp(dB)= 92.45 + 20*log10(F)+20*log10(d)
Lp = Path loss
F= frequency in GHz
dB = decibels
d= Distance in kilometers
Example:
A distance of 6 kilometers provides a free space loss of 115.67 dB at 2.4 GHz.

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2.1.4 Line of sight
Radio signals generally require a clear path between antennas. It is necessary to
know the requirements of a clear path (known as ‘line of sight’).
Line of Sight (LOS) means a bit more than the words say. Of course the first
condition for a LOS link is that the two antennas can be connected with an
imaginary straight string. There should never be any object blocking this line.
Achieving this with a short link is fairly easy. Long links, however, can cause
problems. As well as binoculars and a compass, a large calibrated tether balloon
can be used for determining line of site. Letting this balloon up on one side until it
is visible from the other side will tell you exactly the required height for this link.
Repeat this for both sides.
Besides the LOS there is the Fresnel zone. This zone is an elliptical area
immediately surrounding the visual path. It varies in thickness depending on the
length of the signal path and the frequency of the signal. The necessary
clearance for the Fresnel zone can be calculated, and must be take in account
when determining the height of the antennas.
Figure 2.2 Line of Sight and the Fresnel Zone
A rule of thumb for the clearance needed above and below the signal path (H2) is
that for every 1.5 km, a clearance of 4 meter is necessary. A result of this rule is
that large distances need great heights.

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2.1.5 The link budget
For each link, a ‘link budget’ needs to be made. The link budget will calculate the
signal level through the link, and predicts the signal level at the receiver’s side.
Within the ‘link budget’ there are a few parameters that are influenced by the
location of the link. These are humidity and terrain roughness. The length of the
link also has a major influence on the ‘link budget’.
An example:
We want to bridge a point-to-point distance of 2.5 Km over average terrain in a
dry climate. The bridge must perform at 11Mbps.
To be able to do this, we first select the components we need. This is the long-
range bridge and a high gain helix array antenna.
The output power of the long-range bridge is (Pout): 10 dBm
Antenna gain is (Gt): 16 dBic
Cable loss and connector loss is (Cr): 4.5 dB
Therefore, the EIRP (effective isotropic radiated power) is:
EIRP= Pout + Gt - Cr
EIRP= 10 + 16 – 4.5
EIRP= 21.5 dBm
The free space loss is the attenuation of the signal power travelling through air.
FSL= 20*log10(F) + 20*log10(d) + 92.45
Where:
FSL= Free space loss
F= Frequency (Ghz)
d = Distance between antenna (Km)
Our example gives
FSL= 20*log10(2.4) + 20*log10(2.5) + 92.45
FSL= 108.01 dB
Then the antenna on the other side of the bridge will receive the signal. This
antenna has the same gain (16 dBic) as the transmitting antenna. The signal
received by the antenna will suffer the same attenuation on the cable, (4.5dB).
So the signal strength at the receiver can be calculated as follow:
Pin= EIRP – FSL + Gr - Cr
This results in:

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Pin = 21.5 – 108.0 + 16 – 4.5
Pin = -75.0 dBm
This signal is a calculation under ideal circumstances, however, the radio path
can be disturbed by weather conditions, or antennas can suffer degradations. For
this there is a safety margin included. This margin is called the FADE margin.
Many factors can influence the fade margin; it is safer not to be optimistic about
it. A valid value is approximately 5dB.
This results in a signal level of –80 dBm. The receiver requires a minimal level of
–84.1 dBm to perform at the highest bitrate. Therefore, we can conclude that this
link will work.

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2.1.6 Mechanical Installation of the Antenna
A solid mechanical installation of the antenna is the base of a quality link. An
outdoor mounted antenna is exposed to extreme weather conditions. Metal
brackets oxidize, and vibrations will cause slack on connections. Therefore, the
mechanical connection between the antenna and its carrier needs to be solid.
Use locktite on screws. The connector between the cable and the antenna needs
to be sealed with threading tape. Corrosion on the connector will cause signal
losses due to changing impedance of the connection.
Outside mounted antennas are lightning strike sensitive. Lightning strikes always
are common at highest and smallest point, typically an antenna. The antenna
cable will then conduct the enormous amount of energy towards the bridge. If no
lightning arrestor is placed in-between the antenna cableand the bridge, the
bridge unit will be damaged, or worse, set on fire. Therefore, always use a
lightning arrestor.
When placing the antennas the following points should be kept in mind:
•Place the antenna above conducting objects and in the clear
•Place the antenna always on the edge of a roof or mounted on a wall
•With an outdoor installation of the antenna, always use a lightning arrestor
•Make sure that the mounting of the antenna can handle high forces. Wind can
cause misalignment or even permanent damage
•Keep the cable length between the antenna and the bridge limited to the
minimum. Every meter of cable causes signal loss
•Antenna cable should be a low noise cable such as LMR-400

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2.1.7 Antenna Installation Hints
1. Contract with a professional for antenna installation
2. Determine the antenna location
•Line of sight
•Make sure your antenna fits the range
•No large conducting objects in the area
•No other antennas close
•When mounting on a pole: Let the antenna rise above the pole
•Remember that trees grow!
3. Mount the antenna
•It can never be too solid
•Use Locktite with screws
•Seal connectors with threading tape
•Use a lightning arrestor
•User low noise cable such as LMR-400, LMR-200, or LMR-195.
4. After installation
•Double check

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2.1.8 Lighting protection
Lightning strikes can cause major damage on equipment and buildings. An
antenna placed on a roof is often the place of strike. Dish antennas mounted
against a wall are less risky. The cable conducts the lighting into the building.
Due to this behavior an antenna installation requires dual protection. The
antenna needs to be grounded, and the cable requires a surge protector.
Contact a local lightning specialist for advice on grounding. Below are some
general hints on lighting protection:
•Never mount an antenna though the roof, only on the roof
•Keep the antenna cable as much as possible out doors
•The cable shield needs to be grounded on the highest possible point, and at
the point of entering the building.
•Place a surge protector on the antenna connection at the bridge, and also on
the power supply of the bridge
Lightning protection is a profession. A specialist supplies a professional
installation that reduces the risks of damage caused by lightning strikes.
I-O advises always use a professional lightning specialist.

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2.2 Basic Alignment of the Antenna
Due to its directive behavior, an antenna needs to be aligned. Alignment is done
by maximizing the antenna signal and by minimizing phase noise. The phase
noise directly influences bit error rate. The alignment is essential because certain
weather conditions can degrade the signal strength. Also essential to obtaining
the strongest signal is the use of a low noise antenna cable. To avoid link
dropouts with bad weather, the antennas need to receive the strongest signal
possible with the lowest possible phase noise. In most situations a high signal
level means a low bit error rate, but it does not go without saying. In some cases
the lowest Bite Error Rate is reached at a signal strength level that is not the
highest possible.
The bridge has a Radio Signal Strength Indicator (RSSI) and a SQ2 indicator.
These indicators need to be used during alignment. Both indicators are displayed
at the same time.
To be able to read the RSSI and SQ2 the bridge needs to be connected to a
computer via a small hub. This computer needs to be equipped with an Ethernet
card. The set-up depicted in figure 2.3 needs to be made.
NOTE: The bridge unit is equipped with two antenna connectors (1 & 2).
Always use connector 1, Connector 2 is only used in special cases by an
experienced installer. For information about using the second antenna
option, please contact I-O.
Figure 2.3 Interconnection during installation

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Picture 2.4. The power connector
Picture 2.5. The Ethernet connector
At the remote location, connect the antenna and bridge unit the regular way. Only
the antenna needs to be connected, the network does not have to be connected.
If you have a directive antenna, aim it at the other antenna.
Figure 2.6 Basic setup of two bridge units.
This diagram is based on a 10Base-T (RJ-45) connection. This connector is
located on the backside of the bridge unit. Picture 2.4 shows the Ethernet
connector. After interconnecting the units, they can be powered up. The power
switch is next to the power connector. See picture 2.3.

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Figure 2.7. The led indicators
The LED indicators (figure 2.7) display the status of the bridge. The power LED,
on the right, displays the power status. Green means a correct power feed, red
indicates wrong firmware or power failure.
The LED in the middle displays the network status. If the bridge is connected to
a network it will light-up green, otherwise it will be red or off.
The left-hand side LED displays the radio link status. The client bridge unit
function of this LED differs from the server bridge unit. The radio link LED of the
server will blink as soon as it is transmitting a beacon, approximately 10
times per second, even if there is no connection to the client. The client will
blink as soon as it receives a beacon. It is this function that is used for the first
alignment.
First, install the server side of the bridge. Aim the server antenna (unless it is an
omni antenna) towards the client side of the bridge. Then power up the server
side.
Secondly, the client side needs to be installed. Aim the client antenna towards
the server side and power-up the client unit. This should result in a blinking radio
link LED at the client side. Please remember the server radio link LED will always
blink, while the client LED blinks only when it receives a beacon. If the client
radio link LED is not blinking, realign the antennas (both server and client side).