It all started with 1G, of course, which is also called analog cellular. There were at least nine different technologies here, with all the consequential incompatibilities. But, most importantly, as demand built, it became critical to improve spectral efficiency – the number of simultaneous calls per unit of spectrum and unit of time that could fit on a given carrier’s spectrum in a given locale. And, of course, it also became more important to get more spectrum in the first place, another issue entirely. So we went to digital cellular, a/k/a 2G, and GSM became the dominant technology here. Contrary to popular belief, 2G wasn’t about improved voice quality or any form of data services, again, just about getting more calls on the air. But data soon became important, and packet data at that, which led to the introduction of GPRS, often called 2.5G, and offering throughput on the order of 100Kbps. 3G is an evolution of 2G, but broadband, with data services of up to 2 Mbps defined, and today we even have 3.5G, mostly in the form of HSPA, which can offer peak speeds well above 2 Mbps.

Which leads us to 4G. There is, as yet, no official or widely-accepted definition for what 4G is. Many believe that the ITU, which codifies such things, will settle on 4G as being defined by data throughput of 100 Mbps. I don’t think this is a good idea – first of all, that’s clearly a peak speed that won’t be realized by us mere mortal users. And more importantly, it would cost a small fortune to offers such a service to a given user, and we still won’t be able to support very many simultaneous users in any given location at those kinds of speeds.

I think, then, that a better definition of 4G is basically analogous to what we want from landline communications and networking services – digital, broadband, wireless, mobile, all-IP, and with support for time-bounded services like voice and video. Now, neither WiMAX or nor its chief 4G competitor, LTE, offer voice today. But both have defined voice services, and both, in my book, therefore qualify as 4G. I think LTE is going to be the big winner here because it is the logical evolution of GSM and UMTS, the 2G and 3G, respectively, services with the largest market presence. You’ll start to see LTE become available this year from Verizon, with AT&T and T-Mobile joining in later. But as for critical mass, as I call it, being able to depend upon reliable 4G coverage in major business locations around the country, don’t hold your breath – it will be, I believe, around 2105 before this is a reality for most of us.