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4G LTE – How Coexistence Banishes the Upgrade Bogeyman

Thu, 08/11/2011 - 10:55am
Ofer Saban, Corning MobileAccess

2011 has become the Year of 4G, and for good reason – improved operational efficiencies, satisfying customer demand for better mobile browsing, a new stream of revenue, and the list goes on. But rarely mentioned in any of these glowing 4G stories is the upgrade process, especially when it comes to in-building wireless.

Despite what some industry watchers have said, 4G is not immune to the dampening effects of buildings. Just like 2/3G before it, 4G services degrade the deeper they have to go into a structure. This inevitable degradation  –  coupled with a more demanding Signal Noise Ratio requirement to support data communications – can result in poor in-building service. To overcome this issue, enterprises, arenas, airports and other large venues are choosing to invest in a distributed antenna system (DAS) to strengthen indoor coverage and capacity.

Ofer SabanDAS, however, is not always the answer enterprises want to hear, especially if they lack an existing in-building wireless solution. Obviously, if a building already has a DAS installed, an upgrade can be quite simple, but for a facility without in-building wireless, the situation becomes more complex. Some distributed antenna systems require extensive new cabling and renovation to existing infrastructure, an effort some businesses simply may not be ready or willing to tackle.

So what's the answer? Oddly enough, it lies within a technology that is often considered to be at war with 4G: WLAN.

Is There a Rivalry?
While 4G is often positioned as a WLAN killer and, conversely, that WLAN makes 4G less important indoors, the truth is that both technologies are a bit lacking in some regards. 4G signals degrade much like any other wireless service when entering an indoor environment. This means that much of the touted 4G benefits to business, from electronic medical records to high bandwidth enterprise applications, fall short of their promises indoors.

Conversely, WLAN is a workhorse for the enterprise indoors, but can be easily overloaded by bandwidth-hogging devices and applications, not to mention the fact that the service is limited to the indoors. Melding the two services just makes sense, especially as devices are becoming increasingly service "agnostic." Allowing users to leverage the wireless protocol, whether 4G or WLAN, offers the best connectivity and bandwidth at a given moment, and ultimately, provides the best user experience.

4G as a Hitchhiker
From a logistics perspective, nearly every office building, hospital, airport and convention center has some kind of WLAN, meaning its walls are rife with CAT-5e/6 cabling. While not typically used in DAS installations, these cables can efficiently transport cellular traffic  –  at a different frequency  – without impacting WLAN services.

In essence, upgrading indoor wireless service to 4G via WLAN infrastructure should consist of the following:

• Pre-existing CAT-5e/6 cabling
• A cellular signal controller
• Multiple cellular access pods

With this technology, the cellular access pods shift cellular signals to intermediate frequencies and transmit the signal over CAT-5e/6 cables back to the cellular signal controller. There the signals are converted to their original frequency for transmission. The 4G signal is enhanced and no additional cabling is needed at all. More impressively, since 4G over WLAN uses the existing cabling infrastructure, it is significantly cheaper than traditional active DAS and can cut deployment time in half.

As for coexistence, WLAN and 4G signals actually play quite nicely with each other over CAT-5e/6, a fact that has been verified by some of the industry's leading WLAN equipment manufacturers. Since the two signals are transmitted at different frequencies, there is no cross-talk or harmonic interference between the two technologies, making a conjoined 4G/Wi-Fi solution a perfect fit for indoor wireless needs.

Why Should A Business Care About 4G?
A small (and growing smaller) subset of the business community continues to argue, "I don't need cellular service indoors if I have WLAN."  This argument becomes less and less valid each and every day.

For starters, if a business is any kind of public venue or is concerned with guest satisfaction, indoor wireless is a must. Mobile devices, from smartphones to tablets, will soon be reaching the billion milestone in the U.S., meaning that more guests will want more connectivity. Using WLAN by itself to satisfy the insatiable need for more applications, more video and more bandwidth on all of their devices will become increasingly complex and prohibitively expensive.

Also consider the rise of the mobile enterprise application. For businesses looking to take advantage of high bandwidth applications like mobile video chat, 4G service indoors can assure better control and connectivity for critical applications  – vital elements for a successful deployment.

Finally, at the very least, businesses should look at 4G as a backup network. If the WLAN is unavailable, 4G over the WLAN infrastructure will continue to work normally, ensuring productivity continues.

4G and WLAN are obviously not mutually exclusive – the services combined provide greater coverage and capabilities than when they are deployed separately. And from an upgrade standpoint, WLAN can make the transition to 4G almost painless, helping businesses stay in front of the ever-growing demand for bandwidth.

Ofer Saban is chief technology officer with Corning MobileAccess.

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