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INTRODUCTION

Governments are keen to encourage the roll-out of broadband interactive multimedia services to business and residential customers because they recognise the economic benefits of e-commerce, information and entertainment. Digital cable networks can provide a compelling combination of simultaneous services including broadcast TV, VOD, fast Internet and telephony. Residential customers are likely to be increasingly attracted to these bundles as the cost can be lower than for separate provision. Cable networks have therefore been implemented or upgraded to digital in many urban areas in the developed countries.

ADSL has been developed by telcos to allow on-demand delivery via copper pairs. A bundle comparable to cable can be provided if ADSL is combined with PSTN telephony and satellite or terrestrial broadcast TV services but incumbant telcos have been slow to roll it out and 'unbundling' has not proved successful so far. Some telcos have been accused of restricting ADSL performance and keeping prices high to protect their existing business revenues. Prices have recently fallen but even now the ADSL (and SDSL) offerings are primarily targeted at provision of fast (but contended) Internet services for SME and SOHO customers. This slow progress (which is partly due to the unfavourable economic climate) has also allowed cable companies to move slowly.

A significant proportion of customers in suburban and semi-rural areas will only be able to have ADSL at lower rates because of the attenuation caused by the longer copper drops. One solution is to take fibre out to street cabinets equipped for VDSL but this is expensive, even where ducts are already available.

Network operators and service providers are increasingly beset by a wave of technologies that could potentially close the gap between their fibre trunk networks and a client base that is all too anxious for the industry to accelerate the rollout of broadband. While the established vendors of copper-based DSL and fibre-based cable are finding new business, many start-up operators, discouraged by the high cost of entry into wired markets, have been looking to evolving wireless radio and laser options.

One relatively late entrant into this competitive mire is mesh radio, a technology that has quietly emerged to become a potential holder of the title 'next big thing'. Mesh Radio is a new approach to Broadband Fixed Wireless Access (BFWA) that avoids the limitations of point to multi-point delivery. It could provide a cheaper '3rd Way' to implement residential broadband that is also independent of any existing network operator or service provider. Instead of connecting each subscriber individually to a central provider, each is linked to several other subscribers nearby by low-power radio transmitters; these in turn are connected to others, forming a network, or mesh, of radio interconnections that at some point links back to the central transmitter.

Meshes trace their history to a branch of finite mathematics called graph theory. A Mesh is a very general form of network, not unlike the Internet. A wireless mesh is a mesh network like any other, but the links between nodes are implemented with a radio of some form. In a radio mesh network, each wireless device is capable of acting as a router as well as an end station; it not only transmits and receives data for itself but passes on data for others as well. As long as you are in range of another device you have coverage. The more devices the better the coverage.

Mesh networks may involve either fixed or mobile devices. The principle is similar to the way packets go around the Internet, data will hop from one device to another until it reaches its destination. Dynamic routing capabilities included in each device allow this to happen. To implement such dynamic routing capabilities, each device needs to communicate its routing information to every device it connects with, "almost in real time". Each device determines what to do with the data it receives. Either pass on to the next device or keep it. The algorithm used should ensure that the data takes the "most appropriate route".

Most importantly, the number of possible links between a given node and any other is potentially much greater than in a wired network, since the actual configuration of a particular wireless mesh need not be determined until it is actually moving data. Paths through the network can change from moment to moment in response to varying traffic loads, radio conditions, or traffic prioritization. Wireless meshes are thus among the most flexible network structures ever created, and these are amazingly adaptable and applicable to many different missions, applications, and markets

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