(Subtitle: Be nice to cellular real estate people - their job is harder than you can imagine.)

Now that we've explained a bit about how technology has helped cellular carriers cram more conversations onto each individual radio channel using both TDMA/GSM and CDMA protocols it's time to examine the more mundane, but equally important method that carriers use to expand capacity: adding more cell sites. (For those interested in a much more detailed explanation of how cell phones work, see the wonderful, detailed analysis at "HowStuffWorks.com" by clicking the image to the left of this text.)

This may seem like a pretty easy thing to do, and, in fact, it was at one time, but it's not so much anymore because of how far the expansion process has already come. It's enough to make the people in the real estate acquisition department of the cellular companies pull their hair out - or at least turn it a little gray. Here's why:

When cellular systems were first developed there were no portable phones. The very first portable phone was the "DynaTAC," invented by a good friend and former partner of mine, Marty Cooper (Motorola's Chief Scientist for many years). It was lovingly referred to as "the brick" by its users and probably made most famous by the scene of Gordon Gekko holding one on the beach at sunrise as he called his flunky, Bud Fox, to berate him about not being aggressive enough (while he, Gordon, paradoxically admires the subtelty of the sunrise).

So, all phones were "mobile" - meaning that they were mounted in your car.  What does this have to do with expanding cellular systems?  Hang on a minute... we're getting there.  You see, with a phone mounted in your vehicle you had two things that you don't have with a handheld phone:

1. An external, signal-boosting antenna.  You'll remember all the little "pigtail" antennas that mounted to the window, trunk or roof of a car... when you pulled up to a stoplight you could always tell who had a phone in their vehicle.
2. Unlimited battery power.  With a portable cell phone you need to conserve battery power but with a phone mounted in your car the battery was unlimited - meaning that you could blast a signal a great distance and not worry about depleting the battery.

There were other phones, of course, that offered a quasi-portable solution.  A "bag phone," which put the phone in a carrying case about the size of a lunchbox that you could sling over your shoulder, and the "briefcase phone" which, well, you figure that one out on your own. 

In any event, back to expansion of the cellular systems.  The thing is, with this unlimited battery power and external antenna setup the phones could "talk" to a cell that was a great distance away.  So, many systems started out by having cell sites that were as much as 10 miles apart.  When it came time to expand the system it was relatively easy to do so by adding additional cells, which gave the system more channels covering the same geographic area and thus the ability to handle more calls.  

Eventually, the systems became more and more heavily used and the need for additional channels became acute - as a result the expansion of cellular systems in from the early 90s on skyrocketed.  At about the same time technology became more sophisticated and the electronics shrank, giving the manufacturers the tools to create small, and then tiny, portable cellular phones.  The drawback of these tiny phones, however, is that they also have tiny batteries.  In order to provide service to people without immediately depleting their batteries - which would happen if the phone had to "shout" to the nearest cell site instead of just "talk" to it - cells needed to be more closely spaced to each other so that users were always close to a cell.

In the end, the two movements - smaller cell phones and cell sites closer to each other - complemented each other and pushed each other towards faster development than anyone thought possible.  What ultimately happened, though, is that the size of the cells became so small that the ability to find just the right location for them became exponentially more difficult.  When a cell was 10 miles in diameter and an engineer wanted to "split" the cell, meaning doubling the number of channels by adding another cell in the same space as the first one covered, the real estate people could locate that site anywhere within, say, an eight of a mile radius.  Now, when cell sites themselves cover an eight of a mile - or just a few hundred meters - finding a place to locate another cell within that geographic area becomes increasingly difficult.  

What was in the past relatively easy now becomes incredibly difficult - and expensive.  When the engineers want to split a cell and have to locate it within a very small radius they tell the real estate people to find a suitable site on the northwest corner of Main and Elm streets.  Not the southwest corner, and not the corner of Main and Oak, just one block away.   Which also means that the people who own the property at the northwest corner of Main and Elm street can demand a higher price for their site, because word has gotten around that when a cellular company comes a-calling, you can strong-arm them a bit because they are frequently desperate for that location.  It's not always the case, but it happens often enough to make the lives of cellular real estate acquisition people occasionally miserable. 

Finally, on top of it all, once a site is found there are often protests by the local residents who don't want their view or neighborhood spoiled by the sight of a cellular tower.  These, of course, are the same people ranting at the cellular companies when they can't get coverage in their driveways or homes.  There's a solution to this problem, to, which we'll cover in a future post, all about "stealth" cell sites. 

Until then, the next time you make a call from your cell phone, look around... given the size of the cell sites in today's systems you're almost bound to be able to see the one that's handling your call.