Nortel meshes with BT and MIT

Infrastructure. The boring part of networking. Boring but expensive to do right. The hidden pieces that make a network operate have to quietly provide consistent service in the face of increasing demands and the occasional fault, Rob Bamforth of Bloor Research.

The traditional 'star' or hierarchical network structures concentrate performance requirements and points of vulnerability as you move closer to the core of the network. This leads to higher costs.

Network costs are one of the prime drivers for the advance in cellular infrastructures for 3rd generation Universal Mobile Telecommunication Systems (UMTS). There's much talk about new multimedia data services, but the reality is cost reduction. To cope with increased numbers of subscribers and increased reliance on service levels, costs need to be squeezed out of the infrastructure.

Despite being a relatively new market, wireless LAN network technologies also need a low cost infrastructure. Public wireless LAN, or Wi-Fi, hotspots have to be connected to the rest of the wired Internet network infrastructure via some 'backhaul' link over a broadband connection. This is usually an expensive part of public hotspot running costs. While the dynamics of the market are currently pioneering and adventurous, these costs will only grow as the infrastructure enlarges.

What about an alternative network topology? Mesh for example.

It's a relatively novel idea, but now Nortel Networks has pushed the boundaries of experimentation with trials with Massachusetts Institute of Technology (MIT) and British Telecommunications plc (BT). The potential cost savings are large. In a mesh network, the nodes, in this case wireless access points can be connected to each other via peer to peer connections. This removes the need for each of them to have a high speed and expensive broadband connection to the network core. Costs are saved on both installation and connection. Nortel estimates there could be a 75 per cent saving on installation and commissioning, and 70 per cent on connection.

Even if that's a high estimate, the potential is significant, and there are other benefits. The whole network becomes decentralised, distributed and more flexible around the edge. This means there is an element of self-healing and self-organising so that it can cope better with faults and this reduces the risk of local network outages.

The hotspots are easy to set up, and by using the mesh approach can be quite large. The 7250 wireless gateway and 7220 wireless access points which Nortel is using in the trials, locate nearby units and create their own routing information automatically. Each access point can connect to a maximum of four others. By employing some intelligence in the antenna, Nortel manages the signal beam so that access points can be as far as one kilometre apart.

Overall, this reduces set-up time and cost by removing the need for extensive radio frequency (RF) engineering and tuning. One broadband connection can then support a number of access points in the mesh across a wider area. Maybe a street of coffee shops could share one line, each with an access point in the mesh to provide coverage. Although the access points can be some distance apart, the end user device, a wireless laptop or personal digital assistant, will still need to be within usual Wi-Fi range of an access point. Typically up to around 50 metres.

The trial builds on the "Business without Boundaries" vision recently announced by Nortel, and certainly seems to be expanding the boundaries of public wireless LAN hotspots and offer an opportunity to reduce cost. This of course is vital if providing public wireless LAN access is to become a truly viable business. ®