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A Build-It-Ourselves Guide to Wireless Mesh Networks
Community Wireless Networks can be designed in many ways. To help you understand these different methods for designing networks, this document covers the basics of what different devices do in wireless networks, and how they can be used in different configurations. Using the knowledge and activities in this document, you can work with others to design the wireless network that works best for your community.
Reading and working through Learn Wireless Basics before this document will help you with some of the concepts used in designing wireless networks. It provides some necessary background information for this document.
Reading through this material should take about 30 to 45 minutes. Working through the activities, or diving deeper into the subject with a group may take longer.
MATERIALS + SUPPLIES NEEDED
- The Worksheet and Solution decks - printed out on 8½ by 11" or A4 paper. Available on the Construction Kit website.
- Pens or colored markers
- A surface to work on
Introduction
Networking
Types of Wireless Networks
MODULE: TYPES OF WIRELESS NETWORKS
There are three major “modes” a Wi-Fi device can use. These modes define the role a Wi-Fi device has in the network, and networks must be built out of combinations of devices operating in these different modes. How the devices are configured depends on the types of connections you want to use between parts of the network.
In discussing these modes and the examples below, several types of devices are used. In addition to the phones, tablets, and laptops you use in accessing a network, routers make up the hardware that runs the network. These routers are defined in Learn Networking Basics, but for the sake of this document the quick definition of a router is a network device that can connect one network to another, determine what traffic can pass between them, and perform other functions on a network, such as assigning IP addresses.
Wireless Device Roles
Wireless Clients (Stations)
Devices such as computers, tablets, and phones are common Clients on a network. When you are accessing a wireless hotspot, or the router in your home or office, your device is the client. This client mode is also known as “station mode” as well.
Some routers can operate as Clients as well, which allows them to act like the wireless card in a computer, and connect to other Access Points. This can bridge two Ethernet networks, or connect to more distant APs.
A Wireless Client is similar to a person in the audience of a play or movie. They are one of several or many people accessing information through the same conduit - someone speaking.
MODULE: TYPES OF WIRELESS NETWORKS
Describe the differences in the two example networks below. What are the roles and relationships between the different colored nodes in the networks?
Quick Activity
Example 1
Role of the Pink nodes:
Relationship between nodes:
Example 2
Role of the Yellow nodes:
Role of the Blue nodes:
Relationship between nodes:
The two networks above are Ad-Hoc and Infrastructure (Access Point) networks. Are there places or times in a social situation where you are in an Access Point or Client situation? Are there places or times when you are in an Ad-Hoc situation?
UNIT: NETWORKING
MODULE: TYPES OF WIRELESS NETWORKS
From the roles above, you can see that Clients always need to connect to an Access Point, and Mesh nodes all connect to each other.
It should also be noted that due to how Wi-Fi is designed, this also prevents different roles from connecting to each other as well.
Access Points cannot connect to each other wirelessly:
Clients cannot connect to each other wirelessly:
Clients cannot connect to Ad-Hoc (Mesh) devices wirelessly:
Access Points cannot connect to Ad-Hoc (Mesh) devices wirelessly:
What connects to what?
UNIT: NETWORKING
MODULE: TYPES OF WIRELESS NETWORKS
In the diagram above:
- (1) represents computers connected with Ethernet cables to the wireless devices. These computers are connected to each other over the Point-to-Point link.
- (2) represents the wireless device setup as an Access Point.
- (3) represents the wireless device setup as a Client, connected to the Access Point.
This could look like the building-to-building connection, as shown below:
Point to Point link - Long Distance Connections
Wireless can be used to connect distant areas. It usually requires very focused antennas - such as a dish - that can send a narrow beam in a single direction. This is discussed in Learn Wireless Basics in more detail.
A single long-distance connection is often called a “point-to-point”, or “PtP” link. The name describes the concept: two points are connected together. This requires two wireless devices: one setup as an Access Point; the other setup as a Client. In the example below, two wireless devices create a simple point-to-point link.
OMNIDIRECTIONAL ACCESS POINT AND CLIENT
MODULE: TYPES OF WIRELESS NETWORKS
In the diagram above:
- (1) represents computers connected with Ethernet cables to the wireless devices. These computers are connected to each other over the Point-to-Point link.
- (2) represents the wireless device setup as an Access Point.
- (3) represents dish antennas that focus the wireless signal, allowing connections over long distances.
- (4) represents the wireless device setup as a Client, connected to the Access Point.
This could look like the network below, where an AP mounted on a tower is able to connect with a Client device in a home very far away, since the dishes are facing one another.
Point to Point links continued
LONG-DISTANCE DIRECTIONAL ACCESS POINT AND CLIENT
MODULE: TYPES OF WIRELESS NETWORKS
Point to MultiPoint continued
In the diagram above:
- (1) represents the connection to the Internet.
- (2) represents small Access Points distributing wireless service inside the building.
- (3) represents a powerful omnidirectional (all direction) antenna, sending the wireless signal to a large area around the building.
- (4) represent Client wireless devices on the roof of other buildings, linking to the powerful Access Point, and able to connect to the Internet through that AP.
- (5) represents an Access Point providing the signal for Client devices to connect to.
MODULE: TYPES OF WIRELESS NETWORKS
Mesh - Neighbor-to-neighbor Networks
A mesh network takes the principle of Point-to-Multipoint, and extends it so every node connects to every other node in range. This creates a “Multipoint-to- Multipoint” network. All the devices must be in Ad-Hoc mode - wireless devices in AP mode or Client mode can’t perform the same function. For more information on how this principle works, see the Introduction to Mesh document.
The diagram below demonstrates one model for how this works. Mesh nodes are installed on the rooftops of buildings, and those nodes that are in range will connect. These nodes will share all resources connected to them - such as local applications or connections to the Internet. They can also be connected to computers, Access Points, or routers inside the buildings so users can access the resources anywhere on the network.
In the diagram above:
- (1) represents the connection to the Internet.
- (2) represents a Mesh Node with a connection to the Internet, with an omnidirectional (all directions) antenna.
- (3) represents Mesh Nodes with omnidirectional (all directions) antennas. These nodes are receiving Internet access from Mesh Node 2. They may be connected to different devices inside the building.
- (4) represents small Access Points distributing wireless service inside the building.
MODULE: TYPES OF WIRELESS NETWORKS
Hybrid Networks continued
One last note before we move on to the activity - in the examples above, and in the activity that follows, the diagrams focus on building networks across rooftops or from building to building. This is generally the best way to build networks that cover neighborhoods, towns, or communities. In the diagrams, the way people connect to this network isn’t always shown.
Keep in mind that these rooftop routers may not provide connections to users on the ground, or in buildings. A good way to provide these connections is by attaching Access Points to an Ethernet port on the rooftop router. This indoor Access Point can be set up to use the rooftop network as the source of connections to the Internet, or to provide access to applications and servers on the network. A detailed look at this is below:
In the diagram above:
- (1) represents the rooftop wireless device. It could be a Mesh Node, or Client router.
- (2) represents the Ethernet cable running out to the rooftop from the Power over Ethernet adapter.
- (3) represents a Power over Ethernet (PoE) adapter - a common way to power outdoor wireless devices.
- (4) represents an Access Point, connected to the neighborhood or community network through the rooftop router.
MODULE: TYPES OF WIRELESS NETWORKS
Since there are so many ways to build wireless networks to cover your town or community, we recommend working through these pen-and-paper activities. Download the network worksheets and example solutions from the Construction Kit site and try your hand at designing wireless networks.
If you are working through the activity on your own, try printing out the worksheets first and draw in a possible solution to each of the scenarios. You can then review the example solutions and see how your networks compare with some others.
We recommend you work through this activity with a group of your community members, especially when planning and designing a network. First print out a few sets of the network worksheets, and break into groups of two or three people (depending on how many people are gathered). Draw solutions to each scenario, then meet back up and compare all of your solutions to the scenarios. You can also look through the example solutions and compare them to what your groups came up with. Discuss what solutions might be best for your community.
Activity worksheets
MODULE: TYPES OF WIRELESS NETWORKS
Activity Rules continued
- You have a limited amount of equipment available for each network. Each worksheet has icons of the types and number of pieces of equipment. The example below provides three omnidirectional, one sector, and one focused router:
- You can “configure” the wireless equipment in your network to serve any of the wireless roles - AP, client, or ad-hoc node (mesh). The equipment can be any combination of roles, they don’t have to all be the same role. Label each router with an “A”, “C”, or “M” depending on the role.
- You can assume that all of the wireless equipment in the examples are within range of each other - the signals will reach.
- Remember that Clients can only connect to Access Points. APs cannot connect to each other wirelessly, Clients cannot connect to each other wirelessly, and Mesh nodes cannot connect to APs or Clients wirelessly.
MODULE: TYPES OF WIRELESS NETWORKS
Activity Rules continued
- Many Clients can connect to a single Access Point. Ad-hoc (mesh) devices can have connections to multiple other mesh devices at once.
- If you want to connect different combinations of devices together, you can “wire” them together, as if you plugged an Ethernet cable in between the devices. This way devices that normally cannot connect wirelessly can still be networked. For example, an Access Point or Client can be connected to a Mesh node with an Ethernet cable.
Now download and print the worksheets, and try out some designs!
