Feature Article

March 18, 2015

Cooper's Law of Spectral Efficiency

Martin Cooper, inventor of the cell phone, has been portrayed on some TV commercials for Mazda automobiles walking with his original cellular phone. That breakthrough in technology was extraordinary (and is compared to said automobile in the ad), but perhaps his invention has caused us to miss the insight of Cooper’s law.

“Cooper found that the ability to transmit different radio communications simultaneously and in the same place has grown at the same pace since Guglielmo Marconi's first transmissions in 1895. This led Cooper to formulate the Law of Spectral Efficiency, otherwise known as Cooper's Law. The Law states that the maximum number of voice conversations or equivalent data transactions that can be conducted in all of the useful radio spectrum over a given area doubles every 30 months.”

I bring this up because some advocates talking to FCC are trying to keep wireline technologies alive. The studies make the case that fiber is the efficient way to go and needs to be the priority for government use of the Universal Service Fund [USF].

I have two issues with this analysis.

My first is that advocating fiber to the premise has been overpromised and under-delivered. It would be tangential to discuss the data here, but the essential thing to say is fiber is the best aggregation strategy for wireless systems. However, the local loop can be costly to manage and maintain and cellular has a distributed architecture which should mean a more redundant system in emergencies. 

When incentives were given via the BTOP stimulus initiative, certain companies maintained that DSL was the best broadband for their area. 

My second point is that point to point deployments to the premise are limiting.

Today most broadband users have a Wi-Fi connection to their carrier’s service and as the opportunity for connectivity increases the devices connected continue to increase.

So the premise of the report to FCC starts with a false positive for premise services.

A better scenario is to see the core of the network continue to benefit from fiber and the access to that network continue to benefit from Cooper’s Law. And there is no end to spectral efficiency in the near future, as Verizon pitches LTE-A, Wi-Fi starts doubling the letters of the alphabet in its standards and other technologies such as beam forming, Time Division (Reborn), Frequency Division and other sharing techniques being discussed if not deployed.

We can have lots of rationale why we advocate based on the legacy networks, but when it comes to the greenfield strategy, I would find it hard not to believe that consumers are willing to give up their nomadic freedom.





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