Radioactive: Taipei gets meshed up

There has been plenty of bluster in the past about covering entire cities or districts with meshed Wi-Fi but one city is intending to make this vision a reality. Futurity Media's Stewart Baines investigates what's cooking in Taiwan.

Not content with constructing the world's tallest building, Taiwan also wants the crown of the most wire-free nation on earth. In 2001, Taiwan was the first country to break through the threshold of more phones than people. It is also a broadband powerhouse, with penetration in excess of 16 per cent of the population, ranking it fourth in the world.

Now it intends to tackle broadband wireless. The capital city Taipei has been undergoing a gigantic public infrastructure project to provide almost ubiquitous public Wi-Fi coverage. When it is complete by the end of 2005, there will be 10,000 access points covering 90 per cent of the city. The M-City, or Mobile-City, project has been constructed in two phases. The first turned a lot of heads when it was announced last year. More recently unveiled was phase two, which includes coverage of the entire city rail network.

To my mind, this is the largest wireless citynet on earth. Planning, building and managing this many hotspots for the public good is going to be one hell of a headache. The builders, a local firm called Qware, are investing around $70m in the infrastructure. They believe the secret of M-City's success will be in how mesh technology performs.

Unlike 'traditional' hotspot networks, where each access point or small group of them has its own fixed line to carry internet traffic to the cloud, M-City is relying on a mesh network, where each access point, as well as being open to Wi-Fi devices, backhauls traffic from the next access point. Should there be interference or unexpected outages, the access point should automatically search for another access point to peer to. There will of course be connections to the fixed core network but these interconnections will be kept to a minimum.

The idea of mesh networks, and they are equally applied to the fixed world, is that they offer a great deal of redundancy. Like the internet, any-to-any connectivity ensures traffic is diversely routed over the optimum path. Wireless mesh networks have the advantage however of being considerably cheaper. For fixed networks to have any-to-any connectivity they need a direct connection with multiple other nodes on a network. That can mean a lot of hardware, software and cables.

But in the wireless realm, one-to-many is only incrementally more expensive than one-to-one. The ability to mesh is already in the common or garden domestic access point.

So far, meshing has not been used commonly in commercial networks though that is changing. UK developer Telabria is building a meshed hotspot service based on its own technology, while some community groups in the US have tried to link home networks together using Wi-Fi into a community net. In one of the more unusual trials, the US Department of Energy is experimenting with wireless mesh networks and sensors to dim the lights left on during daylight. It estimates that keeping lights on in homes and businesses accounts for nearly a third of electric use.

The key reason why mesh has not had an impact so far on commercial Wi-Fi services has largely been due to spectrum and site planning. Although Wi-Fi doesn't need a direct line of site connection, objects do interfere, which is particularly important if the nodes can't see each other. Trees and cars and other objects that move can play havoc unless their location and behaviour is mapped.

Nortel, which provided much of the wireless mesh equipment for Taipei, worked with Wireless Valley to model how the mesh would perform in the real world. But instead of having to visit each site, they have been simulating the mesh network on a computerised model of the deployment area. By examining the impact of obstacles such as buildings, cars and trees, they believe they can ensure better resiliency and redundancy, and ensure substantially faster rollout. For Taipei's wireless internet users, the proof of the pudding will be in the eating.

These may be early days for wireless mesh networking but it has a bright future. One of the first hurdles - surprise, surpise - is standardisation. Because each node relies on those next to it to interoperate, they need to speak the same lingo. When the industry Wi-Fi guerrillas are in the same room, finding common ground is not so easy but the IEEE is currently in the process of slogging out 802.11's finer points.

Beyond Wi-Fi, mesh will inveigle its way into other wireless network topologies. RFID and M2M (machine-to-machine) are both set to get the mesh treatment, and rumours persist that 4G will be mesh-based. Each device will be own its own network router, relaying data to the next node (another 4G) phone. That means less base stations, less fixed lines and possibly, less telcos.

For the poor telcos desperately fighting fixed-mobile substitution with their own fixed-mobile convergence, mesh could prove one more nail in the coffin.

Stewart Baines is a freelance journalist and director at Futurity Media.