Fedtech Communication
FW2001BRS / FW2001BRC
Wireless LAN to LAN bridge
User Manual
Version 1.0.0 ¡V Feb 2001
User manual
FW2001BRS / FW2001BRC
Wireless LAN to LAN bridge
Version 1.0.0 ¡V Feb 2001
Trade marks
Copyright © Fedtech Communications Co. Ltd.
The publisher reserves 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.
Other product and company names are registered trademarks or trademarks of their respective holders.
Copyright statement
No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, whether electronic, mechanical, photocopying, recording, or otherwise without the prior writing of the publisher.
Printed in Taiwan, Feburary 2001 23
Statement of Year 2000 Compliance
Detailed information about our statement is published on our website.
http://www.fedtech.net
FCC Radiation Exposure Statement
This equipment complies with FCC radiation exposure limits set forth for an
uncontrolled environment. This equipment should be installed and operated with
the minimum distance between your body and the antenna as shown in the table
below:
|
Low gain indoor antennas (£6dBi) |
4.5cm (1.8 inches) |
|
High gain outdoor antennas (>6dBi) |
30cm (12 inches) |
Warning: It is the responsibility of the professional installer to ensure that when using the outdoor antenna kits 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.
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 Fedtech Product Warranty and may expose the end user to legal and financial liabilities.
Fedtech
and its resellers or distributors are not liable for injury, damage or violation
of government regulations associated with the installation of detached antennas.
1.0 Introduction.......................................................................................................... 7
2.0 Hardware installation....................................................................................... 9
2.1 The antenna installation............................................................................... 10
2.1.1 Radiation diagram............................................................................................. 10
2.1.2 Multi path......................................................................................................... 11
2.1.3 Free space losses............................................................................................ 13
2.1.4 Line of sight..................................................................................................... 14
2.1.5 The link budget................................................................................................ 15
2.1.6 Mechanical installation of the antenna................................................................ 17
2.1.7 Step by Step installation................................................................................... 18
2.1.8 Lighting protection............................................................................................ 19
2.2 Basic Alignment of the antenna................................................................... 20
2.3 Configuration of the bridge units............................................................... 23
Antenna settings....................................................................................................................................... 24
2.4 Fine tuning of the bridge Link....................................................................... 25
The alignment.......................................................................................................................................... 25
2.5 Installing the bridge unit.............................................................................. 27
3.0 BConfig configuration program.................................................................... 28
3.1 Installation....................................................................................................... 29
3.2 The network configuration.......................................................................... 30
Community string..................................................................................................................................... 31
Set a fixed IP address.............................................................................................................................. 31
Change write community........................................................................................................................ 31
3.3 The device settings......................................................................................... 32
Encrypt link using security...................................................................................................................... 32
Contention window.................................................................................................................................. 32
ACK window.............................................................................................................................................. 33
Short retry limit.......................................................................................................................................... 33
RTS/CTS threshold.................................................................................................................................. 33
Long retry limit........................................................................................................................................... 33
Fragmentation threshold........................................................................................................................ 33
Antenna settings....................................................................................................................................... 33
Regulatory domain................................................................................................................................... 34
Channel...................................................................................................................................................... 34
ED Threshold............................................................................................................................................ 34
Some other notes..................................................................................................................................... 34
3.4 Resetting the bridge....................................................................................... 35 4.0 Troubleshooting................................................................................................ 36
5.0 Specs..................................................................................................................... 37
5.1 Bridge specs..................................................................................................... 37
5.2 Omni antenna specs (art number 10380125)................................................. 39
5.3 Sector antenna specs (Art number 10380114)............................................ 40
5.4 Dish antenna specs (Art number 10380103)................................................. 41
5.5 power supply specifications....................................................................... 42
Thank you for purchasing the Fedtech Wireless LAN to LAN Bridge. This manual will assist you with the installation and use of the bridge.
The package you have received contains the following items:
A wireless bridge is used to create either a point-to-point or a point-to-multipoint link between two or more local area networks.
The minimal set-up consists out of:
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 optimised link; he also supplies you with a professional mechanical installation.
The professional installer covers the following areas:
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 are 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
Figure 1.2: The back panel of the wireless bridge
HINT: Before you start, write down the MAC addresses of both units. These addresses are located on the backside of the unit and are difficult to access after installation.
This chapter describes:
The installation of the antennas
The installation and configuration of the FW-2001BRS and FW-2001BRC units
Connecting the antennas to the units
Before starting the installation, some understanding of antennas and their behaviour 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.
The bridge units are supplied with a choice of three 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 this diagram versus the isotope. The gain of the isotropic source is the unity or zero decibels.
Depending on the directive behaviour of an antenna and the site requirements, the type of antenna is chosen.
This diagram displays the radiation power versus the direction. Figure 1.1 displays the radiation diagram of a patch antenna.
Figure 2.1,The radiation diagram of a patch 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 useless, unless the range between the two antennas is short. In such a case the choice for an omni-directional antenna is a purely economical.
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 receiption |
|
Random |
Random |
Variable levels |
The conductivity of the reflector and polarisation of the wave before reflection primarily affect the level of the signal. Horizontal polarised signals, which are parallel to the reflecting surface, will reflect almost totally without appreciable loss at the point of bounce.
Vertically polarised 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 lossy materials, energy can be lost to heat generation.
Refraction
The velocity of RF energy is delayed with prolonged passage through dielectric materials that are denser than dry air. This is refraction, or the change of direction of propagation. The time spent in the denser material controls the degree of refraction and the resulting direction of the emerging wave.
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 polarisation 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.
A choice of three antennas can be made; the table below describes the characteristics of each.
|
|
Omni antenna |
Sector antenna |
Dish antenna |
|
Gain |
8 dBi |
18 dBi |
24 dBi |
|
Alignment accuracy |
Low |
Medium |
High |
|
Multipath sensitivity |
High |
Low |
Low |
|
Size |
Small |
Medium |
Large |
|
Costs |
Low |
Medium |
Medium |
|
Range |
1Km |
3Km |
6Km |
The gain of the antenna is directly linked to the range. According to the above table, it is clear that a dish should only be chosen when a distance of 3km or more needs to be covered.
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 minimise 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.
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 distance from the source. We compute the loss path between the source radiators with spherical patterns using the following equation:
Lp(dB)= 92,45 + 20log10 F+20 LOG10d
Lp= Path loss
F= frequency in GHz
dB= decibels
d= Distance in kilometres
Example:
A distance of 6 kilometre provides a free space loss of ¡V115,67 dB.
Radio signals 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 both side.
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
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.
Think about the following things if you have to determine the line of site:
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 has also got a major influence on the ¡¥link budget¡¦.
An example:
We want to bridge a point-to-point distance of 4,5 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 dish antenna.
The output power of the long-range bridge is (Pout): 2 dBm
Antenna gain is (Gt): 22,2 dBm
Cable loss and connector loss is(Cr): 4,5 dB
So the EIRP (effective isotropic radiated power) is:
EIRP= Pout+Gt-Cr
EIRP= 2+22,2-4,5
EIRP= 19,7 dBm
The free space loss is the attenuation of the signal power travelling through air.
FSL= 20Log(F)+20Log(D)+92,45
Where is:
FSL= Free space loss
F= Frequency (Ghz)
D= Distance between antenna (Km)
Our example gives
FSL= 20Log(2,4)+20Log(4,5)+92,45
FSL= 113,12 dB
Then the antenna on the other side of the bridge will receive the signal. This antenna has got the same gain (22,2dBi) as the receiving signal. 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:
Pin= 19,7-113,12+22,2-4,5
Pin= -75,72dBm
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. A lot of different 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 ¡V80,72dBm. The receiver requires a minimal level of ¡V84,1 dBm to perform at the highest bitrate. So we can conclude that this link will work.
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 oxidise, 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 cable 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:
1. Determine the antenna location
2. Mount the antenna
3. After installation
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 behaviour 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 advise on grounding. Below are some general hints on lighting protection:
Lightning protection is a profession. A specialist supplies a professional installation that reduces the risks of damage caused by lightning strikes.
Fedtech advises to always use a professional lightning specialist.
Due to its directive behaviour an antenna needs to be aligned. Alignment is done by maximising the antenna signal and by minimising phase noise. The phase noise directly influences bit error rate. The alignment is essential because certain weather conditions can degrade the signal strength. 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 got 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.
Picture 2.3 Interconnection during installation
Picture 2.4. The power connector
Picture 2.5. The Ethernet connector
On the other side of the bridge, connect the antenna and bridge unit the regular way. Always use the antenna connector 1 for this, the network does not have to be connected to it. If you have a directive antenna, aim it at the other antenna.
Figure 2.6
This diagram is based on a 10Base-T (RJ-45) connection. This connector is located on the back side 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.
Figure 2.7. The led indicators
The LED indicators (fig.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.
NOTE: The bridge unit is equipped with two antenna connectors (1 & 2). Always use connector 1, Connector 2 is only used inspecial cases by an experienced installer. For information about using the second antenna option, please contact Fedtech.
The left hand side LED displays the radio link status. The client function of this LED differs from the server. 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 onmi 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).
This chapter describes the configuration of the bridge during alignment. This means that certain settings or parameters are not mentioned because they do no effect the alignment of the antennas. Chapter 3 will give a clear description of the meaning of each option, and when to change or use that option.
Start the Bridge Manager program. Firstly, the MAC address of the bridge unit connected to the antenna needs to be entered. The MAC address can be found on the backside label.
Figure 2.8
When the bridge is powered up for the first time, the top IP address field is empty. To set an IP address select ¡¥Set a fixed IP address¡¦; then enter the MAC address, IP address, Subnet mask, and finally the default gateway. If you have a DHCP server within your network you can select the DHCP option, an IP address is then automatically assigned. If you prefer to use DHCP because of its centralised administration, but want a fixed IP address for the bridge unit, you can make a reservation for the MAC address in the DHCP server.
After this information is entered press the ¡¥Connect¡¦ button. Then the system description will display the bridge name and firmware version.
After entering this information select the ¡¥Device¡¦ tab. The following screen will be displayed:
Figure 2.9
In this menu the radio settings can be set. It contains the following options:
SSID (name of the link, both sides need the same name)
MAC properties
Physical properties:
Most of these settings do not require any changes for normal operations. Point-to-point links up to 3 km do not need any changes from the default MAC settings. If the distance exceeds 3 km, increase the minimum of the ACK window to 10.
A new installation does require the SSID, Regulatory domain and Channel to be set.
The SSID
This is the name of the bridge link. The client and the server need to have the same name in this field (the only restriction for this setting).
The Regulatory domain
Some counties have the ETSI rules applied with some minor changes. These changes are often made on the channels that are allowed.
Channel
This setting also needs to be the same on both sides of the bridge. This setting becomes important if multiple bridge links are installed. It could be that one bridge link will interfere with the other bridge link. By choosing another channel, interference can be avoided. Within ETSI the available channel settings are channel 1, 7, and 13. These channels are not interfering and need to be used when bridges are co-located.
The other settings are described in chapter 3. These do not need to be changed for normal use. If you do, however, change the settings and it has a negative effect on the link quality, the settings can be changed back to the original values without damaging the bridge.
Make sure the antenna options selected match your set-up. The diversity option will influence the performance if only one antenna is connected.
The link quality is measured via the Tuning tab. Two quality indicators are displayed. These are:
The tuning selection looks like this:
Figure 2.10
Two lines are displayed. The top one (green) represents the radio signal strength indicator (RSSI), the other (red) represents the signal quality (SQ2).
Before the signal quality measurement can be started, the MAC address of the other side of the bridge needs to be entered in the PEER field.
It is also possible to change the update speed of the measurements.
Remember: If this measurement is activated, no normal IP traffic is possible.
So this mode can only be used during trouble-shooting and installation.
The status bar at the bottom of the screen shows the current status of the link.
The alignment is done by maximising the radio signal strength and minimising the SQ2 indicator. Slowly turning the antenna left and right, up and down, will affect the RSSI. Now start to peak this level.
After finding the peak level, monitor the SQ2 indicator. This indicator displays the multipath effects. Now try to peak this indicator by again turning the antenna very slowly in all directions. Once you have found the SQ2 signal peak, monitor the RSSI indicator again and verify that it is still at an acceptable level.
Repeat this procedure on both sides of the bridge several times.
Figure 2.11
The chart below displays the signal level versus the RSSI, SQ2, and the speed. Speed is displayed as a percentage of the maximum. If SQ2 displays 100%, the red line in the tuning screen displays 0. You can use this graph to determine if the throughput fits the RSSI and SQ-2 value the tuning function displays.
The bridge unit should be installed in a dry and temperature controlled location. The bridge units should not be exposed to hostile environments; temperature should not drop below zero or exceed fifty degrees Celsius.
Preferably mount the unit inside; if that is not possible use the outdoor housing. The housing supplied/advised by Fedtech contains a heating element and a sensor.
The antenna is supplied with an antenna cable. Use this cable with your installation. If for some reason this cable is too short, consult Fedtech for another cable. If the cable is too long, do not cut the cable or roll the cable. The length of the cable determines the characteristics of the system.
Note:
If you cut the antenna cable the system will not perform according to the specs. Modifying the cable will void Fedtech¡¦s warranty. If for some reason changing the antenna cable is unavoidable please contact Fedtech.
This chapter describes the configuration program of the bridge. This program allows you to install and maintain your bridge link. It contains an excellent performance monitor for fine-tuning and troubleshooting.
Within this chapter all options in the program are described together with the circumstances in which it is useful to use these setting.
Bconfig runs on any Windows 95/ 98 or Windows NT machine with TCP/IP installed.
To install the Bconfig program, insert disk 1 into your disk drive and run the Bridge Manager setup.exe. The set-up wizard will guide you through the installation process.
Figure 3.1
Select the directory you want to install Bridge Manager in.
After installation is finished you can start the Bridge Manager program. It will start at the network screen. The network screen allows you to enter the MAC address or the IP number of the bridge. It also allows you to set or change the community string.
Figure 3.2
The Network configuration screen.
The bridge can be configured before it is actually installed. The configuration consists of two parts, the wireless settings and the network settings.
The network settings contain the following parameters:
If an IP address is already set, only the IP address needs to be entered at the top field (IP address or DNS name of WBS/WBC). Click the Connect button to continue. The system description will then be shown, the MAC address etc.
If the bridge is connected for the first time, two situations are possible. The first situation is when you have the bridge connected to a network without a DHCP server, and the second situation is where there is a DHCP server installed in the network.
If a DHCP server is used in the network where the bridge is installed, first check the IP address it has been assigned. Then enter that number at the network screen and press Connect. This will display the MAC address, sub-net mask, and default gateway.
If no DHCP server is running select ¡¥Set an fixed IP address¡¦. Then enter the MAC address and the IP address manually. Also, the sub-net mask and default gateway has to be entered. Press Connect. The network side of the bridge unit is now configured. Repeat this procedure on both sides of the bridge.
Figure 3.3
Below you find a summary of all settings in the network settings part.
IP address or DNS name of FWS/FWC:
The configured bridge can be accessed via this field.
The password protection on the bridge settings.
Use DHCP or BOOTP to obtain an IP address.
If a DHCP server is installed, an IP address can automatically be assigned to the bridge.
With this option an IP address can be manually set. First the MAC address needs to be entered. If an IP address is already configured, it will appear after entering the MAC address. Sub-net mask and default gateway can also be entered in to this field.
This option allows you to change the password of the bridge unit. If the LOCK field is flagged, the bridge can not be accessed via the network. It can only be configured directly.
The radio setting can influence the performance of the link. After installation it is essential to go through each parameter and determine the best settings. Some parameters are related to each other, this means that the best combination needs to be found. Pay special attention during fine-tuning to the ED the threshold, ACK window, and the contention window.
In the Device tab the following parameters can be set:
Figure 3.4
Link Name (ESSID)
The link name is the link ID. Both sides of the bridge need to have the same name. This name can be considered the general link name.
The contention window default is 31 to 1023. This is the back-off window expressed in slot time. 1 means 1slot time, which equals 20 microsecond. This parameter may need to be manipulated when the traffic is out of balance or if the link is set to point-to-multipoint. Out of balance means more data upstream then downstream, or vice versa. Having the diversity option selected with in the antenna field will also creates some extra requirements for the contention window. Diversity makes the radio listen to both antennas. This does not happen at the same time; it will constantly switch between the two antennas. So it will listen 1 slot time to antenna 1 and the next slot time to antenna 2. This means that theoretically it can take 50% more time to receive the right signal. Therefore increase the minimum value of the contention window when using diversity.
This is the waiting time for the acknowledgement, again expressed in slot time. 1 unit is 1slot time (roundtrip) and represents 3 km. Increase this number for large distances. 2 represents 6 km, 3 represents 9 km etc. It will not harm the link if the ACK window is larger than the corresponding distance. To fine tune the throughput, increase the number, measure the throughput, and then start to decrease the ACK window while monitoring the throughput. An excellent way of measuring the throughput is the program called ¡¥Bricks¡¦.
The short retry limit sets the number of retries for packets smaller than the number defined in the RTS/CTS threshold field.
Packages longer than this value will be transmitted via ¡¥request to send/ clear to send¡¦ routine. This method of transmitting provides an extremely secure and reliable link, but will slow it down significant. Since the reliability of the link without RTS/CTS communication is already outstanding it is advised to use this option only if complex and hostile environments.
The long retry limit sets the number of retries for packets longer than the number defined in the RTS/CTS threshold field.
This value sets the threshold where above which the packets will be fragmented.
The bridge contains two antenna ports. With this option you can select the following options:
Be very careful selecting the right antenna setting. Having diversity switched on while only one antenna is connected will harm the performance of the link. Also make sure that the contention window is not below 31 if diversity is switched on.
|
Regulatory Domain |
Area |
Permissible Channels |
Bridge Predefined channels |
|
FCC |
United States |
1 ¡V 11 |
1, 6, 11 |
|
DOC |
Canada |
1 ¡V 11 |
1, 6, 11 |
|
ETSI |
Europe except Spain and France |
1 ¡V 13 |
1, 7, 13 |
|
SPAIN |
Spain |
10 |
10 |
|
FRANCE |
France |
10 |
10 |
|
MKK |
Japan |
14 |
14 |
The options displayed in this field are the allowed channels with in the chosen regulatory domain. Use this option if multiple bridges are co-located or an indoor wireless network is installed. With the channel settings, interference of other equipment working in the same frequency band can be avoided.
ED threshold allows you to kill background noise. If there is interference from other weaker signals on the same frequency, the ED threshold can be used for reducing the influence of this noise. If it is set to 0, the unit will adjust itself. 64 represents the highest sensitivity possible. 1 represents the lowest sensitivity.
The tuning tab of the Bconfig program displays the RSSI. The RSSI parameter displays the signal strength, which corresponds with the ED Threshold. For example, if the RSSI displays an average of 44, adjust the ED Threshold to 40. This way you optimise the receiver to the link signal.
As the noise level with in the link goes up, the ED threshold needs to go down.
Fine tuning a link requires knowledge of the IEEE 802.11. For every link there can be an optimal configuration found. Understanding the influence of each parameter is essential to find this optimal configuration. Experiment and monitor each change to reach this configuration.
You can reset the wireless bridge unit¡¦s settings to factory defaults by pushing a paperclip in the little hole, next to the power switch, while switching the bridge unit on.
When you push a paperclip in the reset hole while the bridge unit is switched on, only the lock set by Bridge Manager is deactivated.
Figure 2.5
If the radio LED of the client is not blinking:
If the radio LED of the client is blinking:
Check if the SSID of both bridges are the same
Check if SUBNET mask and default gateway is set according the network the bridge is connected to. (to do this you need to connect direct to the unit, see configuration for alignment)
Check if the unit has got an IP address (again use the first alignment setup)
Check if the average of SQ2 is below 5 (go to monitor screen in Bconfig setting)
Check if the ACK time fits the range.
Check if the network card of the PC you are measuring with can handle the throughput.
If this not results into a stable link, please contact your reseller.
Standards compliance:
Radio/ modem:
Frequency range: 2.4-2.483,5 GHz
1.0Mbps DBPSK
2.0 Mbps DQPSK
5.5 / 11 Mbps CCK
Europe: 13 (3 non-overlapping)
US: 11 (3 non-overlapping)
France: 4 (1 non-overlapping)
Dish Antenna 0dBm
Yagi Antenna 7dBm
Omni Antenna 16dBm
Omni antenna: Max. 1km @ 11 Mbps
Yagi Antenna: Max. 3km @ 11 Mbps
Dish antenna: Max. 6km @ 11 Mbps
Wireless LAN interface:
Standards: IEEE 802.11CSMA /CA
Network Interfaces:
Standards: IEEE 802.3 CSMA/CD Supports 1024 Mac addresses
Connection type: 10Base2 (BNC) and 10Base-T(RJ-45)
Mobility: Seamless roaming across cell boundaries
Mechanical:
Dimensions: 180 x 220 x 40 mm
Environmental:
Temperature 95% humidity (non-condensing)
(US) AC 110V 60 Hz to 9VDC converter Included
(Europe) AC 240V 50Hz to 9VDC converter Included
LEDs: -Ethernet connection
-RF activity
-Power
Utility software included
Due to ETSI limitations the Omni antenna can only be used with the following bridges within Europe:
The omni antenna consists of vertical polarised collinear arrays utilising a patented printed circuit technology for the radiating elements. This rugged antenna is housed in a UV stable ultrasonically bonded polycarbonate random. Installation is easy due to the small footprint, mounting system and the convenient pigtail connection. The Omni antenna is groundplane independent and can be mounted in any direction. Mounting bracket and cable is included.
Frequency 2400- 2500 Mhz
Peak gain 7 dBi typical
Beamwidth ¡V 3dB 22 degrees
Polarisation Vertical
Nominal impedance 50 Ohm
VSWR 2.0:1 Max
RF power average 50 W
Length 40 cm
Pigtail 12¡¨ N-female
Due to ETSI limitations the sector antenna can only be used with the following bridges within Europe:
The sector antenna is designed to cover frequencies between 2300 and 2500 MHz with a VSWR of less that 1.5:1. The small and low profile housing provides a maximum gain of 13 dBi. Easy mounting allows you to apply the antenna in a wide variety of locations.
Frequency 2300- 2500 Mhz
Peak gain 13 dBi typical
Beamwidth ¡V 3dB H 35 degrees
Polarisation Vertical
Nominal impedance 50 Ohm
VSWR 1.5:1 Max
RF power average 20 W
Dimentions 220 x 200 x 28 mm
Pigtail Female TNC
Due to ETSI limitations the dish antenna can only be used with the following bridges within Europe:
The dish antenna is optimised for use with the Fedtech wireless LAN to LAN bridge. It can withstand the harshest environments of snow, wind, rain, and ice. The dish is supplied with galvanised clamps for pole mount or wall mount.
Frequency 2300- 2500 Mhz
Peak gain 22,2 dBi typical
Beamwidth ¡V 3dB 13,8 degrees
Polarisation Linear
Nominal impedance 50 Ohm
VSWR 1,8:1 Max
RF power average 50 W
Dish diameter 620mm
Pigtail Female N
Dish material ABS plast UV resistant
Radome material ABS plast UV resistant
Metal hardware Stainless steel
Temperature -40 to +80 degrees
Weight 2,5 Kg
