Tuesday, February 9, 2010

Power over ethernet (PoE) and a Rural Smart Grid

At AirJaldi's rural wireless networks in the Himalayas, all routers have PoE or Power over Ethernet supplying their power needs. PoE technology uses the same regular ethernet cable you may use at home, and then sends POWER (electricity) over that cable along with the data. (more about PoE and an $8 implementation.)

This simplifies the wiring of your wireless mesh (no power cords necessary) and provides a way for custom wireless routers to supply power to peripheral devices with embedded PoE converters. In this way, wireless routers can become a power as well as information "hub". Simply applying Occam's Razor to the twin problems of rural electricity and communication, we immediately perceive that supplying them both simultaneously is the most simple solution.

The IEEE standard 802.3at for world-wide use of PoE also enables the creation of complex "smart grid" IP-enabled green electrical networks, which will be highly useful for scalable and "bottom-of-the-pyramid" approaches to Green Energy.

Saturday, February 6, 2010

Cognitive mesh trumps repressive governments

Wi-fi mesh is the best choice available, now, for grassroots global connectivity. Even though the mesh is resistant to attack and shut-down, however, it can still be disrupted by large-scale radio frequency interference that floods Wi-Fi's specific operating channels. Similarly, normal interference from other mesh network devices crowding into Wi-Fi's channels can degrade your signal and severely affect the mesh. 

Some of this spectrum interference can be avoided with a combination of directional antennas and modified routing protocols that take a "web of trust" approach to whom can participate in the mesh. But the long-term answer to these concerns is to design your network as a "Cognitive Mesh".

Cognitive Mesh uses "intelligent" router nodes, which can sense which frequencies around it are currently congested or being blocked, and switch the frequency they use accordingly. This technology is very experimental and under world-wide, active research- but it could make large-scale wireless networks very fast, highly reliable, and simultaneously almost impossible to destroy through interference.

This excerpt is from a Dr. Honggang Zhang's laboratory, which researches green wireless technologies and cognitive mesh networks-
"As the radio spectrum usage paradigm moves from the traditional command-and-control allocation scheme to the open spectrum allocation & access scheme, wireless networks meet new opportunities and challenges. Accordingly, we introduce the concept of cognitive wireless mesh networking (CogMesh) and address the unique problems in such a dynamically networking environment. Basically, CogMesh is a self-organized distributed network architecture combining cognitive wireless access technologies (e.g. Cognitive Radio) with the mesh (ad-hoc) structure in order to provide an integrated & converged service platform over a wide range of heterogeneous networks." - Honggang Zhang's laboratory at Zhejiang University

As this description notes, cognitive mesh networks basically combine 2 technologies, Cognitive radio and Wireless Mesh, into a single seamless integration. It is necessary from a commercial perspective, in order to provide very large-scale mesh networks where many people are sharing the same channel frequencies. And it is also necessary to prevent disruption by authoritarian regimes wishing to shut-down free speech and stifle protesters.

Therefore, the use of cognitive mesh networks, particularly cognitive mesh networks with Wi-Fi, is a means by which to create a robust, grassroots technology of direct peer-to-peer communication that cannot be easily shut down by repressive governments.

Wi-Fi mesh and Global Citizens Movement

Mesh networks are a new type of connectivity paradigm. Generally, when talking about wireless internet connectivity, individual are either "passive consumers" or "commercial providers". For example, when you are sitting at a coffee-shop, browsing the internet on a Wi-Fi wireless hotspot, you can only exchange information with your friend across the table by going first to the Wi-Fi hotspot's router and then to your friend. In other words, the Wi-Fi hotspot is the "provider" and you are just the "consumer" or client attached to that hotspot.
However, mesh networks turn this command-and-control schema on its head, by turning every individual connected to the network into a "provider" of internet connectivity. This makes mesh internet incredibly resistant to repressive regimes (please see previous post for more info and pictures of mesh networks.) To take the coffee-shop example up again, you could now send information directly to your friend sitting across the table, without going through any intermediate Wi-Fi hotspot routers, since you yourself are an internet provider in a mesh network. By directly connecting to your friends, and agreeing to pass along their messages in exchange for them passing along yours, a grassroots internet network of potentially very high speeds (<500 Mbps) is created.
The technology behind mesh networks is transformative for both the internet in general, and the Global Citizens Movement in particular. Already there are dozens of diverse users of mesh networks, from citizens to large businesses and governments. The U.S. military uses mesh technology for battlefield communication between military vehicles, for example. The One Laptop Per Child project (OLPC) from MIT and the U.N. incorporates mesh technology into laptops for students in the developing world. Mesh networks are also being used in Haiti to help in the disaster relief efforts and in India to provide broadband internet to rural villages.

You could use one of many wireless technologies to make a wireless mesh- Cellular, Wi-max, Wi-fi, etc., along with any of more than 70 routing protocols.

But making a Wi-Fi (802.11x) mesh network has several advantages-
  • Wi-fi licenses are not required to create large scale Wi-fi networks in many countries, including India since the deregulation of this spectrum in 2005.
  • Wi-fi router hardware is ubiquitous and relatively cheap.
  • There have already been many practical, large-scale wireless Wi-Fi mesh networks established in places all over the planet, and there is shared expertise and experience as a result of this fact.
  • Many free and open source software packages are already available for setting up and running a Wi-fi network.
Wi-Fi also shares the general advantages of wireless over wired communication, like-
  • No cost for laying wires and cables.
  • Easy to deploy in short amount of time
  • Relatively cheap hardware relative to commercial mobile equipment
  • Simple to shift coverage or expand your wireless range

Wi-Fi mesh networks are inherently decentralized, and that makes them stay functional even if power cuts or technical problems prevent some nodes from working properly. This is a major concern, especially in a developing country with poor electricity infrastructure. A mesh can simply "route around" these problem nodes, and the messages still get out. 

This decentralization also makes mesh networks difficult to censor or shut down. See a forthcoming post about making Wi-Fi mesh networks even more resilient against repressive governments through the use of the "Cognitive" mesh.

-How to set-up a Wi-Fi network in the developing world- "Wireless Networking in the Developing World"
-Open-source wireless mesh routing- OLSR

Friday, February 5, 2010

Freifunk Wi-Fi Mesh networks up in 5 cities in Afghanistan

The Freifunk community announced last week that it had successfully deployed 5 wireless mesh networks in 5 different towns in Afghanistan, connecting local schools and libraries to the internet and each-other.

Freifunk uses Wi-Fi, the ubiquitous coffee-shop and home wireless solution, to create large-scale "mesh" networks that share wireless spectrum amongst each-other and can connect to the larger internet. A mesh network (technically, ad hoc mobile network) is newer form of wireless network that has the potential to be transformational as a grassroots, non-centrally-controllable communication platform for the global citizens movement.

A mesh is not formed by any central wireless tower (which could be easily shut down by authorities in repressive regimes) but instead arises naturally from many people directly connected to their local  neighbors. Messages, video, pictures and the internet in general can be accessed by anyone in the mesh, just by jumping from one person directly to the next, in a chain, until you reach the person or website you want.

Mesh nets are resistant to being attacked, since they can just route the messages along a different chain if a particular node is knocked out or shut down. The messages still get out. For this reason, mesh networks are known as "self-healing", because they route around obstacles and attacks.

Wikipedia- Mesh Networking
Wikipedia- Peer-to-Peer (P2P) Network