False claims and failing standards?

With the advent of wireless networking has come convenience, mobility and portability - but not high speeds. Physical, wired local area networks usually deliver faster speeds than their wireless (WLAN) counterparts. This is said to be changing with the advent of chipsets linked to the emerging IEEE 802.11ac networking standard.

Already, vendors keen to climb on the 802.11ac bandwagon are claiming 'three times faster speeds' compared to networks conforming to the 'old' 802.11n WiFi specification. In theory, the new specification (to be ratified in late 2012 or early 2013) will enable multi-station WLAN throughput of around 1.5Gbps and a maximum single link throughput of 500Mbps.

Don't rely on the additional bandwidth promised by 802.11ac.

Andy Robb is chief technology officer of Duxbury Networking.

Unfortunately, not all the messaging associated with 802.11ac is good news.

For instance, the standard's range may not be as far as 802.11n. This is because 802.11ac operates exclusively in 5GHz frequencies, while 802.11n can also transmit and receive in the more crowded, but much longer ranged, 2.4GHz spectrum.

In order to achieve the additional claimed bandwidth, 802.11ac uses more MIMO (multiple-input and multiple-output) spatial streams and high-density modulation, together with a technique called 'channel bonding' - allowing two channels to be used by the same router, thus increasing the data transmission rates.

Here neighbouring wireless routers (or other devices such as Bluetooth headsets and cordless keyboards) need to operate on separate, non-overlapping channels to avoid interference. Channel bonding in such an environment could lead to serious signal quality degradation.

Because it is necessary to limit the number of wireless access points in any given area to obviate overlapping channels, this influences the number of user devices able to be supported as well as the levels of mobility available. What's more, because 802.11ac is being developed exclusively for the 5GHz wireless spectrum, it is unable to match the number of devices supported in the 2.4GHz spectrum.

Up to now, the 5GHz spectrum has been infrastructure-focused and reserved for inter-access point communications, whereas the 2.4GHz spectrum has been client-focused.

In this light, perhaps 802.11ac should not be viewed as a significant change in the way future networks will operate, but as an evolution of current standards - as much as 802.11n was a development of its predecessor, 802.11g. In other words, it's an update and not a transformation.

To be able to realise any of the proclaimed performance benefits of 802.11ac, an upgrade to the client infrastructure will be mandatory. A major overhaul of any wired network backbone will be required to complement wireless access points handling data volumes of up to 1.5Gbps. At least a 10Gbps backhaul infrastructure is needed, representing a large capital expense when cabling, switching and inter-switch links are incorporated.

Nevertheless, 802.11ac chipsets are set to appear in some laptops and notebooks in time for Christmas 2012. Similarly equipped smartphones and tablets are said to ship in early 2013.

Perhaps I'm throwing cold water on 802.11ac supporters' enthusiasm, but it's important to note that the standard's ratification is some way off - it's at draft two at the moment - and it's likely there will be changes between now and then.

There is a clear warning to corporate users: don't rely on the additional bandwidth promised by 802.11ac. Understand that 802.11ac is not the most practical solution - especially not in the short term - despite its supposed benefits.

My scepticism appears to be shared by the major networking vendors, none of whom have announced 802.11ac compatible infrastructure devices to date. I believe they're aware of the difficulties their channel partners will face in trying to market the 802.11ac concept, which sacrifices valuable convenience for 'hoped for' speed.

That said, there is an opportunity for the new technology in 'intra-device' communications in the home - the streaming of HD 3D movies to multiple TVs, for example. Bandwidth limitations naturally remain a key factor in Internet communications.

Another area in which 802.11ac may play a role is '3G offload', a relatively new requirement being investigated by all three major cellular providers in South Africa.

Most of the capacity on existing base stations is taken up by data from smartphone users. This limits radio capacity for voice - phone calls - where the bigger business profit lies.

To improve voice services, providers want to offload data requirements to co-located WiFi networks, and it is in meeting this demand that 802.11ac's strengths could be optimised.