I've had a lot of interesting conversations in recent months on the debate over in-building wireless coverage. There are many alternatives, but everyone wants to know: Is there a single best approach to the question of bringing cellular voice and data to users indoors?
From a radio-coverage perspective, indoors is tough -- much tougher than outdoors when it comes to provisioning reliable wireless service. Radio propagation is always a bit problematic, but when walls, floors, and ceilings are added to the mix, to say nothing of metal objects that bounce signals, and the people and objects that absorb them, you've got issues.
But as we're all wedded to our mobile handsets and other wide-area mobile computing and communications devices, this is a challenge that must be addressed. Unfortunately, as is often the case with problems that involve not just technology, but also economics, politics, and more, there are a lot of variables. Regardless, I think we will arrive at a single preferred, if not "right" approach -- but it's going to take a while.
All of this is critical because I believe we are converging to a fundamentally mobile arsenal when it comes to communications and networking. Why have a desk phone, with its associated costs and infrastructure, if you already have a cell phone? And, of course, that handset is also a key interface for data networking in all forms. So, the problem is simple, at least in one sense: bring cellular signals indoors, and make the signals generated by the handset get out.
The classic solution is a microcell, which is a cellular base station designed for indoor deployment and owned and operated by a cellular carrier. These are often found in large venues -- sporting arenas, conference centers, and the like.
But private office buildings usually turn to a different solution, called a distributed antenna system (DAS). These can take many forms, but it's useful to think of them as repeaters. These can be pricey, depending upon how much wiring is required, and are often single-carrier solutions. But a true neutral-host implementation can serve essentially everyone with transparency and usually good results.
Except that a DAS doesn't add any additional capacity -- it just takes that which exists nearby and spreads it around more appropriately. This motivates the use of femtocells as an alternative. Think of these analogous to Wi-Fi access points, but serving a particular cellular carrier. Femtocells make a lot of sense in residential applications, but the jury is out on enterprise deployments. Again, does a single-carrier solution really make sense here? We have a lot to learn about both the technology and economics of the femtocell approach.
Which brings me to what I think will eventually be the right strategy: Wi-Fi. Essentially all enterprises (and beyond) will ultimately have ubiquitous Wi-Fi coverage, so why not hand off the cellular connection to Wi-Fi, and vice-versa, as necessary?
Sure, not all handsets have Wi-Fi today, and not all Wi-Fi infrastructures are configured to handle voice traffic. And the carriers seem less than interested in terminating their connections over someone else's network, necessitating private solutions today -- often called fixed/mobile or mobile/mobile convergence.
All of these concerns will be addressed over time, as Wi-Fi is in fact essential to the success of the carriers, who otherwise won't have enough spectrum to handle increasing demands for bandwidth, indoors or out. An existing Wi-Fi infrastructure is by far the least costly and most convenient solution to bringing the wireless wide area network indoors.
We're already partially there, in fact: have a look at the recent announcement from DAS leader MobileAccess and Cisco, and the innovative products from SpiderCloud, both of which use enterprise LAN connections to distribute cellular signals. Can the wireless LAN be far behind?
Craig Mathias is a Principal with Farpoint Group, a wireless and mobile advisory firm based in Ashland, MA. Craig is an internationally recognized expert on wireless communications and mobile computing technologies. He is a well-known industry analyst and frequent speaker at industry conferences and trade shows.