Wednesday, February 11, 2015

5G will be "4G on Steroids"

Despite the hype about future fifth generation network mobile networks, it is quite likely that 5G will simply be an evolution of concepts pioneered on fourth generation Long Term Evolution networks.

Among the more-important capabilities are access to multiple networks, built on today’s use of Wi-Fi and carrier networks; small cells; more complex antenna arrays; and a wider range of devices and applications.

As typically happens, new frequencies will be added, since carriers have to maintain existing networks while they add the next generation.

The degree to which millimeter wave spectrum (30 GHz to 300 GHz) will be a feature of 5G is not yet so clear, but is conceivable. The issue is not so much whether millimeter wave frequencies will be important for backhaul (they already are), but how effective they will be for distribution (direct access by mobile and other devices), using sophisticated new antenna arrays (multiple input, multiple output).

Fifth generation mobile networks, most supporters are quick to say, will not be about “faster speeds” or novel air interfaces.

Instead, at least for the moment, the emphasis is on making all access platforms available to mobile and untethered devices, seamlessly. And that will mean 5G is a development of 4G, not a sharp break from 4G.

In other words, all the fundamental concepts already exist, and all the fundamental underlying technologies already are being developed to support future 5G networks.

Those of you with long memories will see the pattern. All new next generation networks are preceded by a period where all marketing emphasizes “compatibility” with the new emerging standard. That is likely to be the 5G pattern as well.

On the other hand, 5G will bring new spectrum to bear, in particular in the millimeter wave area, where much work is being done to commercialize the use of frequencies that historically have been unworkable for communications applications.

Moore’s Law, though, allows cheap processing that enables networks to take advantage of formerly-forbidding millimeter wave frequencies (30 GHz up to perhaps 300 GHz).
In the United States, the 38.6 GHz to 40 GHz band already is used for licensed high-speed microwave data links and the 60 GHz band can be used for unlicensed short range (1.7 km) data links.

The 71 GHz to 76 GHz, 81 GHz to 86 GHz and 92 GHz to 95 GHz bands are also used for point-to-point high-bandwidth communication links.

The issue is whether sophisticated signal processing also will allow use of millimeter waves for local distribution (access) , in addition to trunking (point to point backhaul).

Observers will readily admit there are issues, ranging from propagation distances to atmospheric issues (rain fade) and even oxygen absorption. But at millimeter wave frequencies, extremely high bandwidths are possible, if distance is limited.
Still, 5G is highly likely to  be an extrapolation of trends we already see. Supporters will likely not appreciate the characterization of 5G as “4G on steroids,” but that is likely to be quite correct.

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