Wi-Fi: Mobile Feature or Fundamental RAN?

According to market research firm ABI, more than 300 million Wi-Fi chipsets across a range of consumer products, including routers and phones, were shipped in 2007. ABI estimates that number will grow to more than 1 billion units by 2012. Meanwhile, a recent consumer electronics study commissioned by the European Union revealed that Wi-Fi is well entrenched in homes. The report detailed that nearly half (46 percent) of internet-connected homes across the 27 European Union member countries already use Wi-Fi. The report also noted an incredible 12 percent increase from the 2006 study, as operators and consumers alike demand Wi-Fi for in-building wireless.

Adding Wi-Fi to Mobile Phones
As subscribers become familiar with mobile phones and mobile services, they are beginning to expect more than simple telephone calls. This is pushing operators to deliver more bandwidth for media-rich applications and putting added strain on the cellular network. Given the incredible presence of Wi-Fi in consumer homes and offices, it's natural to consider bringing the two technologies together.

Mobile phones, the largest consumer electronics market in the world, have actually been quite slow to adopt Wi-Fi technology. Of the more than one billion units shipped in 2007, estimates are that roughly 25 million are shipped with Wi-Fi. However, ABI Research projects that the number of Wi-Fi enabled handsets could grow to more than 500 million units by 2012.

Lack of Wi-Fi in handsets is generally attributed to the tepid reaction of some operators towards Wi-Fi in general. As an unlicensed radio technology, Wi-Fi is often viewed as potentially difficult to manage or control. But the reaction is starting to change. Companies like Research in Motion (RIM) and Apple have truly embraced Wi-Fi as a core technology platform for their newest devices. More importantly, the companies have been able to highlight the advantages of Wi-Fi to mobile operators, and consumers are racing to grab them up.

A key trend in the increasing use of Wi-Fi in new smartphones is the rise of flat-rate pricing for mobile data plans. This is a major shift away from the draconian 'per-byte' pricing originally developed by mobile operators. Because these devices heavily rely on packet services, a consumer purchasing an iPhone or a BlackBerry is required to sign up for an unlimited data plan for a flat rate, typically $30/month. It becomes the best interest of the operator to offload as much data traffic as possible onto a local Wi-Fi network. The consumer is paying for data services, regardless of the transport means. Bytes carried over Wi-Fi are bytes not carried over the more expensive outdoor macro network. For its part, RIM continues to be a vocal advocate for Wi-Fi. At the company's recent investor conference, co-CEO Jim Balsillie said he sees 'unbelievable potential' in Wi-Fi.

Wi-Fi: Feature or Fundamental RAN?
Wi-Fi in a mobile phone is typically viewed as a feature of the device rather than a fundamental RAN element akin to the GSM or UMTS radio. This is certainly the case with Apple's iPhone. The iPhone automatically manages the Wi-Fi connection in the home, providing a near-seamless offload of Internet traffic and applications. A YouTube video played on an iPhone at home will likely be streamed over Wi-Fi rather than the more expensive and slower outdoor network.

However, the iPhone still relies on the GSM or 3G network for all mobile services, specifically telephony. When a consumer is at home, his iPhone today must use both the Wi-Fi and cellular radios in parallel to maintain mobile service delivery. This is certainly inefficient from a power management perspective. But more importantly, Wi-Fi is not making an impact on mobile services. Rather than using the Wi-Fi signal to improve cellular coverage or the broadband connection to deliver mobile content faster, the phone uses the existing cellular radio and radio access network. It is this functionality that distinguishes Wi-Fi as a feature rather than a RAN technology. If Wi-Fi were used as a RAN, the phone could connect to the mobile network via IP, and telephony services would come to the handset over the broadband link; the cellular radio could effectively be powered down because all GSM/3G services would be delivered to the phone via Wi-Fi and IP.

Wi-Fi has a lot of advantages as a RAN technology. Clearly, it is already the dominant radio technology for indoor wireless. Wi-Fi can be used to improve the performance of mobile services in the locations where consumers spend most of their time, at home or in the office. Wi-Fi also offloads the macro radio network. When a handset is connected to Wi-Fi for mobile services, it is not connected to the outdoor network. The effect is to free up more wireless spectrum and capacity for users who need it most: those who are outdoors in a truly mobile environment (car, train, etc.). Because the Wi-Fi connection is attached to the fixed broadband network, operators are also offloading the mobile backhaul network. Now bandwidth-intensive multi-media services can be routed directly to the internet rather delivered than through the mobile core network. And mobile voice, data and IMS traffic is delivered to the mobile core network over broadband, rather than through the cellular access network.