In-building wireless, Part 1: Making the case

Poor on-campus cellular coverage is a common problem. Dropped calls, weak signals and workers standing by the nearest window are commonplace in many businesses. Given this challenge, the question is what role the enterprise IT department should play in finding a solution. Is in-building signal quality a problem best left for the wireless operator? Or is the lack of a signal enough of an impetus to move voice calls onto the corporate wireless LAN? After all, there's already an upgrade plan for Wi-Fi, so why shouldn't mobile telephony ride along?

Mobile telephony over Wi-Fi means using Internet Protocol, and IP telephony is already commonplace in many corporate environments. In fact, properly designed VoIP systems are indistinguishable from their circuit-switched counterparts. But the question remains whether telephony over Wi-Fi is mature enough for large-scale enterprise deployments.

In the discussion that follows, we'll examine why IT departments should think long and hard before making significant investments in infrastructure upgrades and a new generation of mobile telephones. We'll also discuss the opportunities that exist today for improving GSM, CDMA and 3G signals on campus. In the second part of this article, we'll address implementation issues.

Is Wi-Fi telephony mature enough?
There are two approaches to running telephony on Wi-Fi. The first involves application-specific handsets, and the second uses dual-mode cellular/Wi-Fi handsets. In either

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situation, signal improvement, capacity planning and RF engineering are absolute necessities. Since the IT department is deploying the network, managers are responsible for making certain that there are no "dead spots" and that there is sufficient capacity on the corporate wireless LAN to ensure that call quality is adequate and that dropped calls are few and far between.

Managing handsets
The issue of handsets for Wi-Fi telephony is a complicated one. Application-specific handsets are used exclusively on campus, and they quickly become yet another device to carry, manage, configure and charge. With the exception of Bluetooth headsets, many accessories are inevitably different from one device to another. Also, like desktop telephones, the dedicated-handset approach retains the less and less frequently used second "office" telephone number.

The thinking behind Wi-Fi telephony is signal improvement for the cellular telephones that workers carry with them every day. Current research indicates that 40% of all business cellular minutes are used in the office, and this is a behavior that many IT organizations wish to encourage – they just want it to work when users need it.

Dual-mode cellular/Wi-Fi handsets are becoming available with support for the Unlicensed Mobile Access (UMA) specification. These telephones add an 802.11 Wi-Fi radio with a few compromises, namely battery life and features like Bluetooth. The current generation of UMA telephones and services is focused primarily on consumers and has yet to attract any corporate customers. Current purchasing for mobile telephones compounds matters because IT departments would need either to centrally purchase the dual-mode handsets or specify handsets for workers to purchase in retail outlets. On top of this, the model for UMA would require carrier re-provisioning of the service to allow roaming onto Wi-Fi networks. This latter feature is an advantage because it lets the user keep one number and allows the transition between networks to be transparent.

A user interface
The challenges for enterprise adoption of UMA can be overcome, but there are alternative dual-mode approaches, especially on the current generation of cellular/Wi-Fi smartphones. These devices can run IP telephony applications that use an available Wi-Fi network. Like the other alternatives, this one has its own limitation in terms of user interface. Instead of a second telephone, there is a second telephony interface – the first is integrated with the device, and the second IP telephony application needs to be operated independently.

A good example of an IP telephony application is Skype, an easy-to-use and well-designed piece of software. Skype works well, and users are drawn to its low cost, but incoming calls on Skype require another telephone number in addition to the office and mobile numbers.

For years, companies have provided their workers with alternatives like softphones and international access numbers, and these solutions have failed because users have opted for the simpler, more familiar user interface of the mobile telephone. Dual-mode handsets merely replace one challenge with another, and the user interface discussion bears this out. Mobile telephones offer the simple user interface and transparent network roaming that continue to be extremely attractive to workers, especially in office environments.

If it ain't broke …
At the beginning of this piece, we asked whether Wi-Fi telephony is mature enough for the enterprise. The answer is no. Workers are comfortable with their mobile telephones, and they continue to use them in the office, where the only limiting factor is signal quality.

Improving in-building performance for mobile telephones is simple enough, and now that companies are re-engineering their Wi-Fi infrastructures, it's a good time to address performance for GSM, CDMA and 3G as well. In the second part of this series, we'll talk about best practices for improving in-building wireless performance.

Continue to Part 2; Best practices for in-building wireless

About the author: Daniel Taylor is managing director for the Mobile Enterprise Alliance, Inc. (MEA), and he is responsible for global alliance development, programs, marketing and member relations. He brings over fourteen years of high technology experience and is well known as a subject matter expert on many of the aspects of mobility, including wireless data networking, security, enterprise applications and communications services. Prior to the MEA, Dan held a number of product marketing and development positions in the communications industry.

This was first published in September 2006

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