15 July 2010

Is there a role for Wi-Fi in offloading traffic from cellular networks?

We are today witnessing a mobile device boom driven by distributed workforces that need secure anywhere-connectivity, and consumers who want always-on Internet access. Smartphone sales grew 29% year-over-year in 2009 to surpass notebook sales (1), and dual-mode (Wi-Fi/cellular) phones and smartphones will more than double from 2008-2013 to 130.9 million units (2).

One consequence of the flood of mobile devices is growing congestion on cellular data networks. Slow and dropped network connections are legion in large metropolitan areas like Beijing, New York, and San Francisco. Cellular data traffic is rising beyond sustainable network capacity, and there are no signs that it abate any time soon.

This problem is compounded by the challenge carriers face in obtaining acceptable ROI from their massive infrastructure investments. Value-added services like video help a carrier’s bottom line, but the more bandwidth-hungry video booms, the greater capacity is squeezed. Sticky new services and applications needed to secure customer loyalty only add to bandwidth woes.

One solution is to offload bandwidth-intensive multimedia traffic to nearby Wi-Fi networks, a process called “cellular offload.” In theory pushing traffic from overcrowded cellular networks onto high capacity, high-speed Wi-Fi networks should alleviate network congestion. The challenge for carriers is ensuring that bandwidth relief doesn’t come at the expense of the customer experience…or at the customer’s expense.

Cellular offload must be simple to initiate, the quality of service on Wi-Fi must be equal to or better than that offered on cellular, and there should not be cost penalties to the user. That’s a tall order. Many a manufacturer of metropolitan mesh Wi-Fi networks that has attempted cellular offload has failed.

Why? Because metro mesh networks were designed for e-mail and Web access, and not high-density, latency-sensitive data, voice, and video applications. Mesh technology is available that can handle these types of applications, Azalea Networks being a noted example, but metro mesh vendors have so fouled the market that customer resistance is high though not insurmountable.

Cost penalties are another concern. Some carriers, ATT among them, are trying to convince subscribers to pay twice for cellular offloading – once for cellular data service and once for a home Wi-Fi access point to handle traffic that the cellular network can’t. Even if the economics did work for a consumer, this stop-gap crumbles the moment users step foot outside their homes. A system-wide solution – not an ad hoc one – is the only way to address the dilemma.

A corollary to Parkinson’s Law says that data expands to fill all available bandwidth. So while some pundits say we’ll obtain bandwidth relief from 4G cellular (most studies say otherwise), those networks will attract applications that are even more bandwidth heavy.

What we need a commuter lane to handle network overspill and ensure that essential and urgent cellular traffic has the bandwidth it needs. Wi-Fi networks can be that path, if constructed correctly and with the right building blocks, and can do so at a price that is affordable to implement on a vast scale.

So let's stop blaming the rising popularity of Web-enabled smartphones and start focusing on using Wi-Fi to solve the problem.

(1) Dataquest Insight: PC Vendors' Move Into the Smartphone Market is Not Challenge Free

(2) Dataquest Insight: Factors Driving the Worldwide Enterprise Wireless LAN Market, 2005-2013