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Will Wi-Fi reign supreme?

Posted: 20 Jan 2009 ?? ?Print Version ?Bookmark and Share

Keywords:Wi-Fi? RAN UMA GAN?

By Steve Shaw
Kineto Wireless

Wireless communication is a given in today's connected world. With more than 3 billion mobile subscribers, the consumer demand for mobility is clear. Such technologies as GSM, CDMA, EV-DO, and UMTS (and soon LTE), have blanketed the globe with wireless coverage so that subscribers never have to be out of touch. There is a natural inflection point between indoor and outdoor environments, however, and a wireless network optimized for ubiquitous global coverage may not be ideal for delivering wireless services indoors. While cellular has been the undisputed king of outdoor wireless services to date, Wi-Fi dominates the indoor market.

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.

Some Wi-Fi, please
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 1 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 smart phones 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.

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.

Transforming to RAN
As a RAN technology, Wi-Fi is a perfect complement to today's outdoor macro network. Wi-Fi augments the capacity and capabilities of the cellular network and does it faster, cheaper and indoors. Today's 801.11g Wi-Fi technology operates at a theoretical limit of 54Mbit/s, certainly faster than today's mobile data rates. In fact, multi-megabit data rates far exceed the processing power in the CPUs of currently available mobile devices. There are other benefits as well. Wi-Fi operates in a single, harmonized spectrum band worldwide. Thus, a mobile phone with Wi-Fi can use the radio technology anywhere. As a local radio, Wi-Fi is de-coupled from an operator's RAN evolution (GSM, 3G, LTE and so on). The Wi-Fi in the home or office does not become obsolete when a new cellular network comes along.

It is important to note that simply adding a Wi-Fi radio to a handset does not turn it into a RAN technology. The early implementations of Wi-Fi focused heavily on data applications and bursts of large data packets. Even today, when Wi-Fi is offered as a feature on a phone (like the iPhone), it is optimized primarily for data services. To employ Wi-Fi as a RAN technology, the radio needs to be optimized for telephony services and for use in a power and space constrained environment.

The Wi-Fi Alliance has specified a series of recommendations for a voice-optimized implementation. The WiFi Multi-Media (WMM) specifications make specific references to features needed to leverage Wi-Fi for voice service delivery. There is also an extension to WMM called 'PowerSave.' This is a unique power-saving feature that lets the Wi-Fi radio in a device 'sleep' between transmit and receive functions. Both the handset and access point save messages, which are exchanged only at pre-determined intervals and thus enable the radio to reduce power draw. Industry experts estimate that this power-save feature can result in a 20 percent reduction in battery drain. There are many other optimizations, which also result in improved performance for voice services over Wi-Fi networks. Commercial off-the-shelf Wi-Fi chipsets can easily obtain performance levels that meet or exceed those of today's cellular networks.

Mobile service delivery
In addition to optimizing the Wi-Fi radio for mobile service delivery, a standardized protocol is required to connect the handset over Wi-Fi and IP to the mobile core network. Today, every successful dual-mode service where Wi-Fi is a RAN technology relies on the 3GPP unlicensed mobile access/generic access network (UMA/GAN) standard.

Of the more than 1 billion handsets shipped in 2007, estimates are that roughly 25 million are shipped with Wi-Fi.

UMA/GAN was standardized in 3GPP several years ago and delivers a seamless mobile experience, enabling a subscriber to move between cellular and Wi-Fi networks without dropping a call or data session. The essence of UMA/GAN is that it creates a secure tunnel between the handset and the mobile core network so that all existing mobile voice, data and IMS services are delivered to the handset as if it were connected to the macro RAN. This ensures the subscriber receives a consistent user experience (address book, call logs, etc.) regardless of the network in use. The elements of seamless handover and a consistent mobile experience are critical aspects for mobile operators, who pride themselves on delivering a uniform service on the outdoor macro network. Delivering anything less over Wi-Fi should not be an option.

UMA today
Today there are more than 10 operators around the world providing UMA/GAN-based services that use Wi-Fi as a RAN technology. Plus, there are nearly 25 dual-mode handsets which support UMA technology.

Orange/France Telecom is one of the operators most aggressively leveraging Wi-Fi as a RAN technology. In France, Orange offers a service called Unik that lets subscribers use any of the company's 4.5 million installed base of Wi-Fi access points to improve coverage and mobile performance. In addition, Orange offers a 'home zone' service. For a small fee, consumers can get unlimited calling when they are connected through Wi-Fi. In September 2008, Orange extended Unik to include new 3G/2G/Wi-Fi/UMA handsets. Orange also announced new UMA-enabled 3G handsets from Sony Ericsson and Samsung.

T-Mobile in the US is also using Wi-Fi to augment its cellular RAN and deliver home zone services. As the name states, 'Unlimited HotSpot Calling' offers consumers unlimited flat-rate calling when they are connected to Wi-Fi for a small fee on top of a monthly service plan. In addition, consumers can attach their phones to Wi-Fi access points anywhere in the world to improve coverage.

The connected home
By pushing Wi-Fi and UMA/GAN technology into handsets, operators have the ability to deliver an experience commensurate with the macro network but with added benefits.

Today's mobile network does not differentiate between cell locations when a subscriber makes a call. But with UMA and Wi-Fi, the mobile network can now determine if a subscriber is on the high-performance, low-cost IP network or the traditional cellular network. With this information, it is possible for applications on the handset to behave differently. For example, a streaming video service might upgrade the frame rate and audio quality to take advantage of the bandwidth available on the fixed network. Or an internet radio station might convert to high-definition streaming when on Wi-Fi. It is also possible for the network to realize the subscriber is in a specific location, such as his home or office. This presents an opportunity to augment traditional mobile services with 'location awareness.' For example, a mobile phone could generate an SMS when a person enters or leaves a facility, automatically updating a loved one or a social networking site.

Building on these concepts, it is possible for a dual-mode phone to have applications that only run when the device is on a Wi-Fi connection. The phone could automatically synchronize with a media play or upload photos when on the low-cost Wi-Fi network. With Wi-Fi, a UMA-enabled phone quickly becomes part of the connected home.

Today there are more than 10 operators around the world providing UMA/GAN-based services that use Wi-Fi as a RAN technology.

Poised to rule
Wi-Fi is set to play a critical role for mobile operators in the future. Increasing mobile usage is pushing operators to invest in technologies to offload the macro network. The proliferation of Wi-Fi access points in the home and office, where subscribers spend most of their time, makes the broadband access network an attractive option for service delivery. Yet Wi-Fi alone isn't enough. Beyond the protocol optimizations, it's UMA/GAN technology that makes Wi-Fi a RAN technology, extending the mobile network over IP. It's clear that Wi-Fi is poised to become the highest-performance, lowest-cost, indoor RAN technology on the market.

- Steve Shaw is vice president of market development at Kineto Wireless.

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