Powerline networking: The Convergence of electricity and Ethernet

Electricity and computer networks can be one and the same thing – from two different perspectives.

Convergence as a concept essentially describes the idea of merging two formerly separate items – devices or services – into one. The advantages of doing this include the use of fewer materials, greater flexibility, improved efficiency and better usability.

In the world of networking, convergence has held centre stage for some time, especially with the hype around Voice over Internet Protocol. But another convergence, which aims to send additional traffic over existing networks, has taken place as well. Countries with some level of development typically have many networks interconnecting various services – road, rail and electricity grids are among them. While some of these networks cannot be harnessed for data transmission – sending data over the road in a literal sense presents serious problems – it is quite possible to establish Internet connectivity using the power grid, and send power over the networks that connect computers.

There are essentially two ways of converging computer networks with those that carry electricity. They are Power over Ethernet (PoE), defined by the IEEE standard 802.3af, and Broadband over Power Line (BPL). PoE approaches the issue from the Ethernet point of view, delivering electricity using the familiar Ethernet cabling. PoE allows Internet data to be transmitted over utility power lines.

PoE has some useful advantages – subscribers do not need a phone, cable or satellite connection, but rather use a modem that plugs into a wall outlet. However, it also has some serious drawbacks and is unlikely to be adopted on a large scale, especially with the growing availability of high-speed, long distance wireless solutions such as WiMAX. These drawbacks include interference with avionics systems, which has been recorded in the USA, as well as the reality that putting many services onto a single network creates a single point of failure. Where electricity networks are not reliable, this would simultaneously make Internet connectivity unreliable and therefore unworkable for applications demanding reliability.

Looking at PoE, which carries power over the Ethernet network, there are two concerns that must be addressed. The first is that when power is carried over data cables, one has to be very careful with the engineering around it as it causes ‘crosstalk’ or interference with the data. This requires taking a step back and looking at the reasons for wanting to power devices through the data cable. If the device was a phone, perhaps, it would be feasible – but, then, with advances in ‘soft’ technology (such as softphones), the need for power delivery through a cable becomes restricted to niche applications.

Essentially, both these technologies are workable, but have already largely been superseded by better solutions that are more practical – and are therefore unlikely to experience widespread success.

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Powerline networking: The Convergence of electricity and Ethernet