Just as is the case with wire, we've seen a steady advance in both the throughput and the price/performance of wireless networks of all forms. As I've noted before, there is of necessity an inverse relationship between range and throughput in terrestrial wireless systems. In brief, the farther you go, the slower you go.
This is an essential result of what's known as the inverse power law, which states that the power of a radio transmission fades with the square of distance, or exponentially. This also explains -- along with other forms of radio-wave fading and regulatory bandwidth restrictions -- the highly variable throughput we're always likely to see in wireless, and why the range and throughput numbers for any given wireless product or service must be evaluated separately. Maximum range never applies to maximum throughput, and vice versa.
In the early days of wireless, however, the laws of physics and expensive base-station equipment demanding large coverage areas, coupled with inherently low-performance radios (we just didn't have the technology for wireless broadband 15 years ago), meant that the whole model of wireless data in the wide area was oriented around low throughput and thus the requirement for a high tolerance of latency. One of the most important technologies in these days was paging, a service allocated its own set of frequencies by the Federal Communications Commission and originally designed around the concept of a beeper -- call a number, enter the beeper's ID, and the device carried by the user would literally beep. That person would then find a pay phone and call in for the message. This was back in the days when equipment was expensive and people were cheap.
Well, it didn't take too long for paging service to be significantly enhanced, first with numeric paging, which displayed the phone number to be called right on the beeper, and then alphanumeric paging, which was a form of one-way text messaging. Then this was extended with what was called "one-and-a-half-way paging," more accurately described as "acknowledgment paging," where a pager could transmit an acknowledgment that the message had been received. And then we had true two-way paging with two-way short message service.
Many cellular carriers eventually offered messaging services as well, and when cell phones began to catch on in the mid-1990s, paging quickly saw the handwriting on the wall. It was possible for a while to make such claims as significant cost savings when using both a pager and a cell phone, and this was true until cellular rates fell dramatically. The low bandwidth and relatively high latency of paging networks also weren't suited to those staples of modern messaging, multimedia data objects and sending digital photos around. Cellular services usually include Short Messaging Service or Multimedia Messaging Service with no additional hardware required. It looked, as of the late '90s, like paging's time had finally passed.
Sure enough, there's been a massive consolidation in paging, and we're down to one big national operator, USA Mobility, a couple of smaller national operators, American Messaging and SkyTel, and a whole bunch of regional and smaller operators.
According to USA Mobility, paging subscribers peaked in 1998 at 45 million and sit at a bit below 7 million today. Paging is still popular in the health care and government markets, and remains such because of reliability. Paging signals have good in-building penetration and range because they're usually broadcast at 3,000 to 4,000 watts, compared with less than 1,000 watts (and usually only a hundred watts or so) for cellular.
It's likely that the glory days of paging are over, but paging network operators are talking about some exciting new directions -- telemetry, telematics, advertising, meter reading and more.
And paging networks are already in use for "machine-to-machine" applications. Here's an example in the residential energy management space. Owning spectrum -- every little tiny chunk of it -- is always a door to opportunity. So, while paging isn't coming back as a personal communications technology, it is likely that it will be around well into the future in a broad range of unexciting -- but still important -- applications.
Craig J. Mathias is a principal at Farpoint Group, an advisory firm specializing in wireless networking and mobile computing. He can be reached at craig@farpointgroup.com.