4G: What & When

11:50 AM -- Sprint’s announcement of its mobile WiMax initiative triggered a flood of calls here regarding 4G cellular. (See Sprint Goes WiMax.) And there’s significant debate about exactly what 4G is. The ITU defines 4G as 100 Mbit/s or more; this makes sense since they defined 3G by throughput as well – in that case, 144 Kbit/s to 2 Mbit/s peak. (See Carriers Look to Define the Future.) But I don’t think a definition based on throughput makes sense, and I want to propose an alternative definition.

Why not use throughput to define 4G? Well, first of all, it’s misleading. The 3G numbers were peak speeds, not SLAs. Wireless throughput numbers are always the ones that marketing departments guarantee their products and services will never exceed. Throughput is all over the place, and always will be; that’s wireless. Secondly, the issue with 4G and 100 Mbit/s is one of economics -- will 4G operators even be able to offer peak throughput of 100 Mbit/s? The cost of spectrum will likely prohibit such services in licensed bandwidth, and no single user would be able to afford mobile, wide-area broadband like that. Finally, most mobile users wouldn’t need that kind of throughput, essentially ever.

So, how about this definition: 4G is mobile, broadband wireless (obviously), based solely on IP and with full support for QOS (classes of time-bounded traffic). Throughput could be in the cable modem/xDSL range; that would be fine, and likely economically viable.

But note that WiFi (surprise!) is already there, save for high-mobility users. That’s coming in future 802.11 standards and the products based on them. WiFi as the first 4G networks? Makes sense to me. And a lot of public-access WiFi is available right now. As for big-cell, licensed 4G -- it’s hard to imagine any volume rollouts for at least five years, and maybe longer. Unlike the 2G/3G transition, the economics of big-cell 4G, as I noted above, may not make sense.

— Craig Mathias is Principal Analyst at the Farpoint Group , an advisory firm specializing in wireless communications and mobile computing. Special to Unstrung

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