Village Telco Introduction Course
Village Telco Logo

Course Aims

  • Introduce the Village Telco.

  • Understand the major components of the Village Telco.

  • Introduction to Mesh Networks

  • Learn how to set up a Mesh Potato and make phone calls.

  • Learn about common Mesh Wifi problems.

The Village Telco

Village Telco Components

Village Telco Figure
  • Between 2 and 500 Mesh Potatoes. The Mesh Potatoes are mounted on short poles on the top of buildings and houses. They form a network with each other to relay phone calls. The phone calls are made using VOIP. Each mesh potato provides a single telephone to the house. Like a land line.

  • The Supernode connects the Mesh Potatoes to the gateway.

  • The gateway connects the mesh network to the regular telephone network and the Internet.

  • A server for monitoring the network and billing.

Instructor: show or hand around each component in class

Village Telco in a Township

Village Telco Ideas

  • Community telephone network. A person in the community or Village maintains the network rather than a big company.

  • No cell phone towers are required. Two Mesh Potatoes can talk to each other without any extra equipment.

  • The idea is to make a small Telco business for someone.

  • A Village Telco network is scalable up and down. Each network can have between 2 and 500 telephones. Larger networks can also be built.

Village Telco and Mobile Phones

  • For local phone calls the call cost can be very low or free.

  • The Village Telco uses a community approach. Your Mesh Potato relays calls from other Mesh Potatoes. Everyone helps each other.

  • The Mesh Potato uses unlicensed Wifi Spectrum.

  • Mobile phone networks don’t scale down. You can’t put a mobile phone base station in a small village as the base stations are expensive and need lots of electricity. A Village Telco network can be installed in any village, as it can scale down.

  • Village Telco phones are fixed. Like a land line, but delivered via Wifi.

Mesh Networks

Regular Wifi Networks

Regular Wifi

An Access Point connects to laptops. All data flows through the Access Point. The laptops don’t talk to each other directly. Range is limited by the distance from the Access Point to the laptop. In this example Laptop C is out of range.

Mesh Wifi Networks

Mesh Wifi

Each device is called a node. A node could be a router, or a laptop, or a special device like the Mesh Potato.

Each node relays data for the other nodes. There is no access point. There is no range limit. A Mesh network could be 10km wide. Mesh networks of up to 500 nodes have been built in Germany.

The mesh nodes automatically find the best route. If one node breaks, the other nodes work out a new route. If you have a poor link between two nodes, you can add an extra node to relay the signal.

However mesh networks are not perfect. Some problems with mesh networks:

  • All nodes are on the same channel, so there can be interference problems.

  • For many hops the bandwidth is lower than a single hop as the message must be repeated many times.

  • Omni-directional antennas are used to pick up signals from mesh nodes in all directions. Sometimes omnidirectional antennas also pick up a lot of interference from other Wifi networks.

Inside the Mesh Potato

Production Mesh Potato
  • Mesh Potato is also called the MP01

  • 180MHz Atheros CPU, 8M byte flash memory, 16 Mbyte RAM

  • FXS port for connecting to a single analog telephone

  • 802.11bg Wifi and Ethernet

  • Protected against static electricity, lightning, bad power. Designed for developing world conditions.

  • Target price USD$60.

  • Linux operating system

  • Asterisk telephony software

  • 10-40V power supply option. Can operate directly from a solar panel with no battery. Uses just 2W.

The Village Telco and Mesh Potato was designed by a team of people from all over the world. It is custom hardware designed to help people in developing countries. Current Mesh Potatoes are Beta units for testing. In the middle of 2010 production units will be made.

Instructor: point out different interfaces on Mesh Potato

Setting Up the Mesh Potato with the GUI

Each Mesh Potato has a unique IP address on the Mesh Network, for example 10.130.1.123. The IP address then becomes the phone number. To set up a Mesh Potato we need to set this IP address.

Instructor: allocate a different IP to each student

  1. Connect your Mesh Potato to a Unbuntu Linux PC using an Ethernet cable.

  2. Start a terminal: Applications→Accessories→Terminal

  3. In the terminal:

    Instructor: supply root password

    $ sudo su -
    # /etc/init.d/NetworkManager stop
    # ifconfig eth0 down
    # ifconfig eth0 192.168.1.4
    # ping 192.168.1.20 -c 5

    The Mesh Potato has a default IP of 192.168.1.20. The ping command is a test to ensure we can talk to the Mesh Potato. Make sure ping to 192.168.1.20 works.

  4. Start your web browser. Point your web browser at http://192.168.1.20. The login user/password is root/admin.

  5. Change the IP Address from 10.130.1.x to 10.130.1.yourchoice. Note there is no save - just move your mouse to another GUI field and you are finished.

    Mesh Potato config GUI
  6. Reboot: Remove the power to your Mesh Potato for 2 seconds then plug the power back in.

  7. To restore your Linux computer network settings:

    # /etc/init.d/NetworkManager start
  8. Wait for the Mesh Potato Wifi LED to blink. This may take 1 or 2 minutes. Then pick up the phone and check there is dial tone.

  9. Make a phone call to someone elses Mesh Potato by dialling the last part of their IP. For example if their Mesh Potato is 10.130.1.123, just dial 123.

  10. Get some one else to call you by dialling your IP.

Instructor run batman -d1 -c on the Supernode to show IP of nodes as they are configured

Setting Up the Mesh Potato with the Phone

Instructor demonstrate, especially show pressing the * button between octets

  1. Switch on the Mesh Potato and wait for dial tone in the telephone (1 minute).

  2. Dial 2663 (CONF using letters).

  3. Wait for the prompt "Just what do you think you’re doing Dave…."

  4. Dial the IP on the telephone, for example 10*130*1*123

  5. Wait a few seconds. The IP will be read back to you.

  6. Count to 5. Hangup the phone.

  7. Reboot: Remove the power to your potato then plug the power back in.

  8. Wait for the Wifi LED to blink. This may take 1 or 2 minutes. Then pick up the phone and check there is dial tone.

  9. Make a phone call to some one elses Mesh Potato by dialling the last part of their IP. For example if their Mesh Potato is 10.130.1.123, just dial 123.

  10. Get some one else to call you.

Mesh Wifi Problems

Line of Site

Line of site is very important for mesh Wifi links. The antenna from one Mesh Potato should be able to see the antenna of another Mesh Potato. Install Mesh Potatoes high enough so that one antenna can clearly see the antenna of the next one. A little extra height can make a big difference. Make sure there are no trees in the way.

Instructor: move a battery powered Mesh Potato away from the class room. Watch the batman score steadily decrease as line of site gets poorer. Listen to the phone call quality as the link gets poorer.

Interference from other Wifi Networks

Wifi nodes share a Wifi channel. Each node listens for the transmission of other nodes. A node will transmit only when the channel is quiet.

Mesh Interference

In this case another Wifi network is using the same or similar Wifi channel. Node A can hear the AP but Node B cannot as it is too far away. So if Node B transmits at the same time as the AP, the messages will get mixed up at Node A.

This is a common problem when Node A uses an omnidirectional antenna and is mounted very high where it can hear many surrounding Wifi networks.

Changing the Mesh Potato location or the Wifi channel can reduce interference.