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 1.
Choosing an ISP
If you have Business-Class Internet service you should have no issues
with allowing outside users to share your network wirelessly. As
a general rule, Business Class contracts do not specifically restrict
any forms of usage within the legal realm. However be sure to check
the Acceptable Usage Policy (AUP) or Terms of Service (TOS) agreement
with your provider.
When you use Residential-Class Internet service, please check the
TOS or AUP of your provider to see whether they allow sharing with
others. The Personal Telco Website maintains a list of ISP policies
with regard to sharing your connection wirelessly (http://www.personaltelco.net/index.cgi/IspWirelessPolicies).
REMEMBER: Even if the ISP gives their permission for you
to share, you are still possibly responsible for whatever traffic
that may originate from your AP/network. Please visit the site
listed above to read more on this topic.
2.
Choosing an Access Point.
Access Point (AP) - A wireless LAN transceiver that acts as a center
point of an all-wireless network or as a connection point between
wireless and wired networks (a wireless ethernet bridge).
2.1 AP Basics
As a general rule, you can use any access point that uses the Wi-Fi
standard and set it up for public use (please see 2.2 AP Settings
below). A few access points (higher priced normally, such as Cisco
Aironet products) offer higher transmit power, 100-mW, compared
to 30-mW of transmit power found more commonly. This can greatly
increase the range of an AP. Some access points offer the ability
to attach external antennas. These external antennas can be used
to also add range to your AP and/or change the shape of the coverage
area. Many AP's function as a wireless Ethernet bridge. They simply
plug into a hub or switch. Another device must perform NAT and/or
DHCP. Some AP's are also routers that are capable of performing
NAT, DHCP and/or even firewalling tasks. Your network needs will
determine what functionality you will look for in an AP. Some AP's
are capable of being powered through the same cable that transmits
data between the AP and your network (called power over Ethernet).
This can come in handy when placing the AP in a location that may
be best for coverage, but difficult to supply electrical.
Lastly, it is noteworthy to mention that whenever you make your
network available for public usage, without setting up any firewall
protection you are as vulnerable as if the remote user were plugged
in to your local LAN.
2.2 AP Settings
The following settings and standards are required of all access
points so as to maintain consistent and reliable interoperability
between wireless devices and the access points that comprise the
tocwireless.net network.
- 802.11b or 802.11g based AP.
- WiFi Certified or offers the same level of compatibility through
settings.
- WEP disabled.
- SSID set to tocwireless.net.
- IP settings assigned through DHCP.
- Long/Short Radio Preambles set to short.
- Public Secure Packet Forwarding is disabled.
- Offer Internet access.
- Must assign IP settings through DHCP
Further Notes:
- Do not allow the AP to autoselect the channel during an AP startup.
Find the best channel and make it static - this will increase
performance and eliminate other problems. For 802.11b, channels
1, 6 and 11 do not overlap.
- You need to have the proper network settings in order to share
your Internet connection, as well as to distribute IP addresses
automatically using DHCP.
- Many ISPs will give you a single public IP Address. To set up
multiple computers to access the Internet, while appearing to
originate from that single IP address, routers use Network Address
Translation (NAT). This allows you to assign your own internal
addressing while allowing you to access external resources such
as the Internet. Common internal network addresses are 192.168.x.x,
10.x.x.x., and 172.16.x.x.
- If you are sharing your home network with the public, i.e. you
are on the same network segment, use common sense security as
you would with any unknown user who plugs into your LAN!
When the AP is set up and functioning, please email tocwireless@townofcarrboro.org
and include the following information:
- Donator: (your name, companies name or anonymous)
- Location: (a basic description)
- SSID: (should be tocwireless.net)
- Encryption: (should be none)
- Channel: ???
- WiFi: (should be yes)
- Long/Short Radio Preambles: (should be short)
- Public Secure Packet Forwarding: (should be disabled)
- Any special comments about range or shape of coverage? Verify
your signal coverage through a site survey (See Section 4 below)!
The Project may be able to help you with a site survey.
Get your AP listed on this web site and placed on the network
map!
When the Project receives this information, your AP will be listed
on this web site and added to the GIS wireless network map. The
Project will also extend to you a GREAT BIG THANKS!! This is a crucial
step to maximum usage of your AP and to expand the network.
The Project is actively seeking hardware donations (wireless AP's).
If you or your organization have bandwidth to offer, the Project
may be able to loan you or your organization the AP.
3.
Antennas & Amplifiers
To add range or modify the shape of coverage, you need to connect
an external antenna to your AP. This will at times significantly
increase your signal strength, and will allow for greater coverage
area for your public AP. With Standard Access Points, it is one
antenna per Access Point. Some higher-end Access Points offer dual
radios built-in, so you can cover two areas with two antennas.
Please note that there are many factors involved in increasing
range, and what may work for one user may not work for another.
A site survey is ALWYAS needed, before and after installation to
determine the best placement of the AP and antenna. The tocwireless.net
Project may offer site surveys in the future, if volunteers come
forward as this Project grows.
3.1 Antenna Basics
An antenna gives the wireless system three fundamental properties—gain,
direction, and polarization. Gain is a measure of increase in power.
Direction is the shape of the transmission pattern. A good analogy
for an antenna is the reflector in a flashlight. The reflector concentrates
and intensifies the light beam in a particular direction similar
to what a parabolic dish antenna would to a RF source in a radio
system.
Antennas are rated in comparison to isotropic or dipole antennas.
An isotropic antenna is a theoretical antenna with a uniform three-dimensional
radiation pattern (similar to a light bulb with no reflector). dBi
is used to compare the power level of a given antenna to the theoretical
isotropic antenna. An isotropic antenna is said to have a power
rating of 0 dB, for example, zero gain/loss when compared to itself.
Unlike isotropic antennas, dipole antennas are real antennas. Dipole
antennas have a different radiation pattern compared to isotropic
antennas. The dipole radiation pattern is 360 degrees in the horizontal
plane and 75 degrees in the vertical plane (assuming the dipole
antenna is standing vertically) and resembles a donut in shape.
Because the beam is “slightly” concentrated, dipole antennas
have a gain over isotropic antennas of 2.14 dB in the horizontal
plane. Dipole antennas are said to have a gain of 2.14 dBi (in comparison
to an isotropic antenna). Some antennas are rated in comparison
to dipole antennas. This is denoted by the suffix dBd. Hence, dipole
antennas have a gain of 0 dBd (= 2.14 dBi).
3.2 Type of Antennas - omni-directional, yagis
and patch antennas
Different types of antennas will offer different coverage capabilities.
As the gain of an antenna increases, there is some tradeoff to its
coverage area. Usually gain antennas offer longer coverage distances,
but only in a certain direction.
Omni-Directional Antennas:
An omni-directional antenna is designed to provide a 360 degree
radiation pattern. This type of antenna is used when coverage in
all directions from the antenna is required. The standard 2.14 dBi
“Rubber Duck” is one style of an omni-directional antenna.
Directional Antennas:
Directional antennas come in many different styles and shapes. An
antenna does not offer any added power to the signal, and instead
simply redirects the energy it received from the transmitter. By
redirecting this energy, it has the effect of providing more energy
in one direction, and less energy in all other directions. As the
gain of a directional antenna increases, the angle of radiation
usually decreases, providing a greater coverage distance, but with
a reduced coverage angle. Directional antennas include yagis, patch
antennas, and parabolic dishes.
Diversity Antenna Systems (seen on many AP's - those two antennas)
Diversity antenna systems are used to overcome a phenomenon known
as multipath distortion of multipath fading. It uses two identical
antennas, located a small distance apart, to provide coverage to
the same physical area.
3.3 Using Amplifiers
Amplifiers can be used to significantly increase signal strength.
4.
Site Survey
4.1 NetStumbler Usage
After you initially setup your Access Point (and possibly antenna),
the next step is to check the coverage of the area to which you
are attempting to provide wireless access. Use NetStumbler to check
signal coverage and open networks around you. You can download NetStumbler
from the NetStumbler website (http://www.netstumbler.com).
There are versions available for Microsoft Windows 9x/NT/2000/XP
and for Microsoft Pocket PC.
4.2 Improving Your Antenna/AP Positioning
Walk around the area you are attempting to cover, and verify that
you have good signal strength. Ideally your location overlooks the
area you are attempting to cover with wireless coverage. The ideal
location for an antenna or AP is a window (you won't have to worry
about water damage or other weather related issues). This window
should not have metal shielding, Venetian blinds, screens, or other
types of obstructions. All of these will reduce the signal strength.
Be aware of foliage during the spring and summer seasons. They tend
to decrease signal strength.
5.
Signage & Logo
The following signage was developed for our purposes, feel free
to modify and use them. Use at your own risk. The Spanish translations
follow the english versions.
5.1 Signage
SIGN 1 (ENGLISH):
Public Wireless Internet Access Area
This public space provides public wireless Internet access to mobile
technology users.
Current wireless public spaces:
Town Hall, Century Center
WLAN standards currently supported:
802.11b
The Town of Carrboro web site:
http://townofcarrboro.org
SIGN 1 (Español):
Area de Acceso al Internet Público inalámbrico
Este espacio público permite que los usuarios de tecnología
móvil tengan acceso al internet público inalámbrico.
Espacio público inalámbrico disponible en La Alcaldía
y en el Century Center.
Los estandares Wylan aceptados o incluídos actualmente.
802.11b
El sitio de la red Internet de Carrboro es:
http://www.townofcarrboro.org
SIGN 2 (ENGLISH):
Public Wireless Internet Access Area
This wireless Internet connection offers unencrypted, unmonitored
(by the Town of Carrboro), unfiltered and free access to all the
valuable resources the public Internet offers.
Please Understand:
1. Use at your own risk.
2. Do not assume privacy.
3. The provided Internet connection should not be used for illegal
activities. The Town will report any questionable activities to
the appropriate law enforcement authorities, if the Town learns
of or suspects that this service is being used for illegal purposes.
4. There is no content filtering or site blocking in place.
SIGN 2 (Español):
Area de Acceso al Internet Público inalámbrico
La ciudad de Carrboro le ofrece los servicios de esta conexión
Internet sin filtro, sin clave, sin supervisión y le dá
acceso libre para todos los valiosos recursos que ofrece el Internet
público.
Por favor tome muy en cuenta lo siguiente:
1. Esta usando este servicio a su propio riesgo.
2. No asuma que este servicio sea privado.
3. Este servicio de Internet no debe ser usado para ninguna actividad
ilegal. La Alcaldía reportará cualquier actividad
ilegal a las autoridades si sospecha que usted está usando
este servicio para asuntos ilegales.
4. No hay filtros ni bloqueadores en esta red de Internet.
5.2 Logo
Here is the Project's logo in PGN vector format. You may modify
the original logo in the following ways. You may modify the size
of the image, as long as, the proportions of all elements are maintained.
If you do not use the animated version, then you may us the version
that has no "signals" emanating from the letter "o"
or the version that has all three "waves" emanating from
the letter "o". No other modification is allowed. Please
contact us if you have any questions. Use your browser to save this
graphic.
Animated PNG w/Radio Waves (will not see motion):
Static PNG w/No Radio Waves
Static PNG w/Radio Waves
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