University of New South Wales researchers have are developing a wireless network system for public transportation that they claim will give passengers total online access. The system, known as Ocean (On-board Communications Entertainment and Information) embodies a technology called "Wireless Multihop," which uses a small router in each vehicle to link to any nearby bus or train.
Associate Professor Mahbub Hassan, leader of the project, explains, "Our protocols are intelligent. They can learn from previous histories which buses or trains are coming soon and which they can connect with. They can even allow for delays in traffic. Our computations using a metropolitan bus network show that there would always be three or four buses within contact at any time."
To avoid problems with network congestion, UNSW researchers are also working on "semantic compression", a system which would "dynamically profile the user, determine what kinds of programs and information they normally access and filter their internet search so only the most relevant data pops up."
In the UNSW news release, Hassan outlined the benefit of the technology. "Public transport cuts down pollution, conserves energy and eliminates traffic congestion. We must do everything possible to make public transport more attractive so it is used by more people. There are other benefits. On-board communication infrastructure will enable remote video surveillance of public transport vehicles leading the way to unprecedented passenger safety and security."
For users, the system would be simple. Hassan said, "Passenger and other vehicle devices will simply connect to the on-board local area network and start using the Internet just like the home or office. "
From the researchers standpoint implementation is more complicated. Hassan outlined the difficulties. "This architecture, although sounds very simple, raises several issues in networking and data management disciplines. These issues must be resolved for on-board mobile computing to really take off. Firstly, any error or outage in the wireless link will immediately affect a large number of users. Additionally, link outages in such systems can be frequent and long lasting -- for example, when a train going in and out of tunnels. Secondly, traffic from large numbers of users can easily overwhelm the wireless link. Thirdly, the population of the network is very dynamic. Passengers are getting on and off the vehicle all the time."
He further noted that the challenge of caching data and providing personalized delivery of relevant information for such a dynamic user group would be formidable.
Mesh networks, such as those using the Zigbee standard, are available now. It will be interesting to see how this "Zigbee on wheels" technology develops.
