Articles and whitepapers

Smart Wi-Fi - Making Wi-Fi Predictable (1/11/2006)

By Mark Mitchell, Ruckus Wireless

Throughout Europe, service providers are launching next-generation digital home services including IPTV, internet and fixed and mobile telephony - all delivered over a single broadband line into the home. Indeed, IPTV uptake is set to explode over the coming years, with Infonetics Research predicting that global subscriber numbers will top 53 million by 2009.

While recent advances in broadband and video compression technologies make it possible to deliver these services to the doorstep, the crucial problem of how to move these services around the home has been largely overlooked. Yet it is this home networking challenge - the last 25 metres - that has the potential to make or break the service.

The broadband connection coming into the home is typically nowhere near the TV. As such, a standard IPTV service today involves the installation of unsightly and inconvenient wiring to all corners of the home. But providers in Hong Kong and Italy are already reporting that the rejection rate for these new services can be as high as 30 percent when the consumer realises the extent of the physical disruption involved. Not only is cabling inconvenient, but it is also time-consuming, with each installation taking two installers approximately four hours. This means that each installer can only activate one or two subscribers per day, whereas the industry benchmark is four. This delay has the potential to kill the profitability of a service before it has even started.

Is Wi-Fi the right choice?

With Wi-Fi becoming the consumer home networking technology of choice, Wi-Fi media devices in the home are expected grow at a compound annual growth rate of 104.7 percent over the next five years. This would seem to be an obvious solution to distributing IPTV around the home. Furthermore, Wi-Fi is quick and simple to install, thus increasing the number of subscribers that installers can activate on a daily basis.

Wi-Fi however, was developed for delay-tolerant data applications, and relies on higher-level TCP protocols for error correction and packet re-transmissions. When it comes to streaming rich multimedia content, current Wi-Fi technology is just not up to the job due to range limitations, unpredictable performance, inadequate quality of service and gratuitous handling of multicast traffic. The result is a pixellated, jittery and disruptive TV service that would simply be unacceptable to consumers.

Problems encountered when streaming IPTV over standard Wi-Fi

Wi-Fi is also a shared media that transmits signals in every direction, and is therefore hard to control. And because signals are dispersed on multiple paths, they may arrive out of phase, creating a condition called multi-path fading. This results in reduced and unpredictable signal strength, temporary dead spots and packet errors.

In addition, anything and everything, including people, can get in the way of the signal, causing interference that makes a video signal unwatchable. Even with emerging, higher-capacity standards, such as 802.11n, video quality over Wi-Fi is unpredictable at best. Yet, many in the industry are relying on the introduction of 802.11n to solve all these problems. In reality, market feedback suggests that 'n' will be subject to the same, if not more, reliability and stability issues than existing Wi-Fi today. Furthermore, 'n' is still a good way off formal ratification - but installers need a solution today.

The Smart Wi-Fi solution

So-called 'smart Wi-Fi' technology - combining MIMO antenna arrays and sophisticated traffic engineering software - has recently been developed to solve these problems. Unlike conventional Wi-Fi, smart Wi-Fi determines what signal paths are available and the quality of these paths given the location of a specific endpoint and the traffic being transmitted to it.

Smart Wi-Fi technology continually ranks and monitors paths using a number of metrics such as signal-to-noise ratio, throughput, packet errors, jitter, signal strength etc, to determine the quality of any Wi-Fi link. Unlike current Wi-Fi technology, smart Wi-Fi signals are also focused in a specific direction, minimising interference and maximising range and coverage.

The Ruckus Wireless MediaFlex smart Wi-Fi system enables broadcast-quality video to be streamed anywhere in the home

If interference or signal quality degrades, these systems quickly switch or steer Wi-Fi signals onto a better path in milliseconds to maintain consistent high data rates while minimising packet errors and re-transmissions.

Innovations in sophisticated QoS software automatically classify different types of IP traffic prior to transmission over smart antennas to ensure the appropriate bandwidth schedule for different traffic profiles. This guarantees that video traffic, for instance, doesn't degrade in the presence of massive data use on the Wi-Fi network.

Smart Wi-Fi systems also identify and handle multicast traffic differently. Smart Wi-Fi systems analyse and sort incoming traffic in queues as specified by 802.11e. Multicast streams are tuned and prioritised to ensure the same service quality levels as unicast traffic.

Conclusion

A stable Wi-Fi link is the only a foundation on which to build the priority queuing necessary to allow a single in-home network to service voice, broadcast quality video and data in the home.

If IPTV and triple-play services are to take off at the phenomenal rate predicted, the problem of the last 25 metres in the home must be solved. While there are many alternatives available today, it is clear that consumers want a viable wireless solution. If it can live up to its promise, smart Wi-Fi looks to be a serious contender.

Mark Mitchell is VP EMEA for Ruckus Wireless. Ruckus Wireless is credited with developing the first 'smart Wi-Fi' system that enables reliable transmission of digital video over standards-based in-home wireless networks.

www.ruckuswireless.com