Despite the ubiquity of WiFi broadband routers, home networking still lags behind its corporate twin brother. Whereas companies have the budget to lay ‘Category 5' or CAT5 Ethernet cable to strategic floor boxes all over an office, only the most obsessed – and financially loaded – home users would do the same.

Instead, most of us rely on 802.11g wireless LANs domestically, which are around ten times slower in real-world performance than wired Ethernet. But with the second era of broadband now arriving, home networking technology could start to be a bottleneck and could even stop you enjoying tasty future possibilities like streaming HDTV around the house.

Power-line networking has always felt like it should be the answer, but until recently performance has lagged even further behind wired Ethernet than WiFi. It wasn't until late 2004 that products based on the HomePlug 1.0 standard even arrived. But the original products were only nominally capable of 14Mbps, similar to the previous-generation 802.11b wireless. And like the latter, real-world bandwidth was much lower. Only with the non-standardised 85Mbps kit, such as Devolo's MicroLink dLAN Highspeed modules (see the review, here), did HomePlug offer performance to compare or even exceed the current 802.11g wireless standard.

Technology moves on apace, though, and the next generations of home networking are fast approaching. And this time, it looks like the power-line option will get the jump over wireless.

Here comes HomePlug AV

The latest version of the HomePlug standard, dubbed HomePlug AV, will soon be with us, offering a nominal bandwidth of 200Mbps. After some very auspicious demonstrations at CeBit in March, Devolo is promising products in Europe July. The product is expected in Australia late in 2007.

If the CeBit demonstrations are anything to go by, we can expect real-world throughput of around 90Mbps, as we reported in our network futures roundup last month. This makes it 4-5 times faster than 85Mbps HomePlug, and at least three times quicker than the fastest wireless kit we've seen, including proprietary MIMO-enhanced versions of 802.11g from the likes of Belkin, Netgear and Linksys.

Best of all, the 90Mbps speed is not far off wired Ethernet. But how does HomePlug AV manage this more than fourfold increase over its predecessor? We asked to Devolo's Werner Fehn to guide us through the technology. HomePlug uses a similar system to ADSL to achieve its high throughput. Using a method called Discrete Multi-Tone (DMT), both HomePlug and ADSL send signals over multiple frequencies at once. Although the amount of data on each frequency may not be that much, putting them all together allows for massive throughput.

In the case of the original HomePlug, data was sent across frequencies from 4-21MHz. But with HomePlug AV, the range extends from 2 to 28MHz. The number of carrier frequencies has increased, too, from 84 to 1,536 – so the wider range is cut up into much smaller bands.

HomePlug AV also uses a different method of multiplexing all the signals from different devices on the network together, compared to standard HomePlug. The latter operates with a system called Code Division Multiple Access (CDMA). With CDMA, all devices talk on all frequencies at the same time, using a code to differentiate the different signals from different devices.

But HomePlug AV uses Time Division Multiple Access (TDMA), similar to GSM phones. With TDMA, the frequencies are divided up into timeslots, which are strictly apportioned to each device on the network by one device acting as the master. The upshot of this is that standard HomePlug 1.0 isn't really designed for more than 12 devices, as interference means performance goes down as the number of devices on the network goes up. But HomePlug AV supports 20 or 30 devices. CDMA also can't guarantee service, whereas TDMA means every device gets an equal share of the time on air.

However, the very different technology used in HomePlugAV means that it isn't backwards compatible with the previous standard. So if you've already bought into any previous devices, new HomePlug AV adapters won't be able to communicate directly with them. The two can coexist, though, as HomePlugAV can detect the presence of HomePlug 1.0 devices on a powerline network and allow them to communicate by limiting itself when the standard HomePlug is active.

Return of the wired network?
With the rubber-stamped specification 802.11n still due in 2007, despite manufacturers like Netgear and Linksys lining up their draft products much earlier, HomePlugAV should have a good six months on the market as the fastest domestic networking standard around.

However, although it's always fun to see differing technologies fight to the death, in truth 802.11n and HomePlug AV aren't really direct competitors anyway, for a number of reasons. As fast as HomePlugAV is, the freedom of wireless will still make it the preferred technology for applications like web browsing from your sofa or Internet cafés.

But on the other hand, wireless can't guarantee service, even with 802.11n, which uses CDMA. So HomePlugAV is likely to be the optimal choice for applications like hooking up your console to the Internet, or streaming TV from your Media Center PC to your bedroom. It's also likely that many people will combine both types of network, and use the one which best suits their needs of the moment. The two technologies overlap, but can complement each other nicely as well.

Devolo plans to bring its HomePlugAV-based dLAN 200 AV range to market at a similar cost to its current 85Mbps products, although exact pricing hasn't been confirmed. Solwise has also announced HomePlugAV products, with availability in late summer, and pricing around twice that of existing 85Mbps equipment. The next home networking speed bump is just around the corner.

James Morris is a writer for Digital Home Magazine a publication that SmartHouse Magazine licences. 

Links:
HomePlug Powerline Alliance
Devolo
Solwise