What's next for Wireless?

Posted on 7 Aug 2007 at 17:48

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Anyone who has bought one of the large number of Draft-N hardware products that have been on the market for months probably hopes that a simple firmware upgrade will be enough to ensure their chosen devices meet the n standard when it is finally agreed. This is likely to be true in most cases. And it is even more likely that Draft 2.0 products will be upgradable to the n standard, although no chipset manufacturers guarantee this at the moment.

Firmware upgrades should be available from the support section of the manufacturer's website or through any proprietary software your equipment may use. For example, Belkin products have a 'check firmware upgrades' button on the bottom-left of its software's menu bar. The software then carries out the upgrade process in the background, without the need for any further input from the user.

Multiple antennas

Why would anyone want to buy a product that doesn't conform to an accepted standard? Early adopters are keen to get the extra power that n-type wireless networks offer. The use of multiple antennas in 802.11n devices, whether internal or external, helps to boost the range and strength of a wireless signal. This not only helps to reduce the number of dead spots in your home or office, it also increases data throughput rates by using multiple data streams simultaneously. The final standard will require n devices to have at least two transmitters and two receivers, although those that have more will also be regarded as standard-compliant. In hardware that adheres to the first and second drafts of the n standard, it is common to see two, three or even more antennas. Devices with more than one antenna will have a MIMO label - this stands for Multiple Input Multiple Output.

Using multiple antennas maximises performance by splitting data into several parts, known as spatial streams. Each stream is transmitted by a separate antenna, and received by separate antennas at the other end. The maths behind the use of additional antennas is quite simple: with two antennas the throughput is doubled, and with four it is quadrupled. But there are drawbacks.

Each antenna draws a certain amount of power, so a device with several antennas has the potential to be incredibly power-hungry. This isn't necessarily a problem for home and office users, but for mobile users it is a cause for concern. To get round this issue, the draft format of the 802.11n standard specifies that devices should include a power-saving mode in which multiple data streams are used only when it results in better performance. This is an issue only if your network is made up exclusively of n-type devices. If it includes equipment that conforms to other standards, you won't be gaining the extra performance, as older b and g equipment can't use multiple data streams unless they are MIMO devices.

This prioritisation of multiple channels is an important feature of 802.11n, and one that will have mass appeal. It is called Quality of Service (QoS), and it does more than just save power. Networking activities such as streaming media and playing games obviously benefit from maximum performance, whereas a minor slowdown in web browsing is much less noticeable. With QoS, traffic that would suffer the most from interruptions can be assigned more than one data stream to help reduce the risk of delays, while less important traffic, such as standard web browsing, can be assigned a single stream.

Interference with existing wireless networks is also less of a concern with the n standard. Products that conform to the finalised standard will operate a 'good neighbour' policy, enabling them automatically to switch the channel they are broadcasting on to one that is further away from those used by nearby networks.