Overview

This document will try and walk you through all the steps to setting up a node on a wireless network. This includes all the parts you need, the setup of your AP/Router and the configurations you will need to apply to get your node up and running.

Assessment

Lets make sure we do our homework on the Community Wireless gig before we go out and spend our money.

Starting or connecting to a network?

Firstly, before you run out and buy all of the required hardware, you need to assess how you will connect to others. Are you joining an existing network? Are you starting up a new network? Is this just a link to setup between yourself and your friend down the road? What routing protocol is the network using?

It is important to get some scope on what purpose your installation will serve. Otherwise you could end up with an expensive roof ornament supported by an under utilised electronic device.

You may want to read our [GettingStarted.html GettingStarted] guide, or post a query on [The-Mesh.html The-Mesh] forums if you're unsure of how to go about things.

Site Surveys

Quite often people will have spare equipment lying around that they can use to survey the surrounding area for wireless signal. This allows you to make an assessment of what to expect if you were to install equipment on your site.

It's generally a good idea to do a site survey before investing equipment, as it helps with assessing what you need, based on the height you need to achieve to get a signal to neighbouring nodes.

Preparation

So what parts and materials will we need?

Roof,mast or other?

As mentioned above, the height you need to gain signal will affect what equipment you end up using - at least for mast installations.

If you are lucky enough to get signal from the top of your roof, then all you will need is something such as a 2m "J-bar" mast like the one you use for outdoor TV antennas.

It may be that you can mount your mast directly to a guide rail on the balcony of your house because you're 6 stories up and have a clear view of the surrounding area.

In cases where you need to gain height by using masts, you need to make sure it is appropriate to do so in your area. If you live in an urban environment, errecting a 20m mast in your backyard might not only be unsafe but illegal. So make sure you check with the appropriate Government department(s) before installing a mast.

Antenna

There are many different types of antennas that you use to construct a wireless network. Each type serve a different purpose, so it is important you do your homework on the antenna you will use, to make sure it suites your setup.

Antennas are generally categorised into two different categories. There is a Directional, which is usually a higher gain? antenna that is used for long distance links (2km+), or when you want to direct your signal into one area, rather than spread across a large area.

Directionals are effective ways to get point-to-point links between two nodes, or to connect back to a node with an Omni-Directional? antenna. A lot of wireless networks use Directional antennas to form a network backbone between network clusters, or meshes.

The other category of antenna is the Omni-directional antenna. This is typically a lower gain antenna that will cover a 360 degree area. It is more suited to a multi-point link. Meaning, it connects to more than one other node via the same antenna.

It can be said that Omni-directional antennas are typically used in Meshed networks?, where you have several nodes in a close area (within 1-2kms), which interconnect with each other using each node as a relay.

Of course there are also Sector antennas, which could be considered the hybrid of the Directional and Omni-directional antennas. These antennas have a slightly lower gain to the directional, but will generally have a larger beamwidth (usually between 90-180 degrees). They are not quite Omni-directional antennas, as they only cover a certain "sector" of the possible 360degrees of beamwidth. However, Sectors will generally have a higher gain compared to an Omni, and can be setup to provide the same coverage as an Omni, just using four Sector antennas. This means bandwidth is not shared by one antenna and radio, you can have four antennas with four radios, providing four times the amount of available bandwidth (also more expensive).

You have more than likely seen Sectors in use on Mobile phone towers.


Types of antennas:

• Directional Parabolic Grid antenna
• Vertical Colinear Omni antenna
• Waveguide Sector antenna

Polarisation

It is important to be aware of what polarisation your network is using. Antennas are either horizontally or vertically polarised. A vertically polarised antenna will not communicate with a horizontally polarised antenna, so it is important the polarisation is the same on all connecting nodes.

Some antennas like grid antennas can change polarisation if you rotate them 90 degrees. However, this is only really effective for directional antennas, as the beamwidth is quite close in both horizontal and vertical alignments. Omni and Sector antennas generally have a low beamwidth on one polarisation, and a high beamwidth on the other.

For example, the Vertical Colinear Omni has a large vertical beamwidth (360 degrees), where it will only have around 20-40 degree horizontal beamwidth. So, it is not so effect when turned 90 degrees.

Antenna beamwidth

Access Point

Coax or Power Over Ethernet (PoE)

Building your node

<Unfinished>

• AccessPoint?
  • [Linksys+WRT54G.html Linksys WRT54G]
  • LinuxWirelessRouter?
• Flashing firmware
  • FreifunkFirmwareFlashing?
• Configuring router
  • FreifunkFirmwareConfig?
• Coax and connectors
  • Types of coax and connectors
  • Loss and noise
• PoE
  • Active and passive
  • Homebrew vs commercial
• Antennas and pigtails
  • Omni
  • Directional
  • Polarisation
  • Pigtail connector types
• Access for maintenance
  • Public or private sites
• Different types of masts
• Lightning protection
• Weatherproofing
• Mounting equipment
• Powering equipment
• Disclaimer
• Feedback