5G Won’t Be What Most Are Expecting

Think 5G means gigabit throughput? Nope. 5G will be all about capacity, not throughput.

5G was a hot topic at the recent Mobile World Congress event, and while a formal definition of 5G is still pending, numbers like 1 Gbps are being tossed around. And, you know what? Such is indeed possible. More speed in wireless is a function of (a) appropriate modulation, antenna technologies, processor implementations and doing well with the requisite technical details, (b) keeping the distance between the endpoints as limited and line-of-sight as possible (smalls cells are, as ever, a very good idea), (c) network operator policies regarding how much throughput a single user might be entitled to, (d) the instantaneous statistical behavior of the radio channel, but most importantly (e) how much spectrum is available. That last point is the key, and also the most difficult. Large chunks of available spectrum at frequencies appropriate for mobility (ideally below 3 GHz, but certainly below 6 GHz.) are hard (and perhaps even impossible, given the long history of wireless and poor, again historically, regulatory policies) to come by. Aggregating smaller chunks is a viable if more complex option, but more spectrum is required regardless.

So offering per-user throughput at gigabit rates, or even applying a reasonable filter of one-third to one-half of that amount in terms of Layer-7 throughput, isn't going to happen. Given the shortage of spectrum, I expect the policy of not committing to any specific level of performance that most operators apply today will remain. Verizon, for example, continues to emphasize coverage, not capacity or throughput, in their 4G advertising, and, as a Verizon customer, I can tell you that throughput and even simple responsiveness are often terrible on their network. Of course, this might be due to the poor performance of the sites I'm accessing, but, regardless, the expected throughput is often just not there.

I suspect the reason for this is that many cellular networks are simply swamped as more and more people demand mobile data services. And all of this leads thus to the conclusion that 5G, whatever form it might take, will follow the philosophy typical in most enterprise Wi-Fi installations today: it's all about capacity, not speed.

While the two are related, capacity is the ability to address the needs of a large, diverse audience with equally diverse application requirements but growing overall demand regardless. While the market for data won't saturate in the same manner as that for voice, the philosophy again will be to provision sufficient capacity (again, not throughput) to satisfy (that is, not necessarily please) most users. Keep in mind, though, that the vast majority of those "users" will ultimately be M2M/IoT devices with highly-variable capacity requirements. Many if not most of these are assumed at present to have flexible throughput and responsiveness requirements, unlike their carbon-based counterparts, so, again, per-user (or per-device) throughput just isn't that important.

So, yes, gigabit wireless WANs are coming (and my guess as to timing remains around 2025 for critical mass). As long as we expect that gigabit to be sliced up pretty fine, everyone will be able to go home happy. I suspect, though, at least given expectations at present, a lot of people are going to go home quite the opposite.

My apologies for being absent recently. I've got whatever cold is circulating here in the northeast, and I'm very bad at being sick. I'm sure this speaks for many across the nation (and across the globe, really), but spring cannot come too soon this year.

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