I remember using the old walkie-talkie radios.  We would always finish each contribution to the conversation by saying “... Over”, meaning ‘time for you to talk now.’  Those were the days of old wireless technologies and respect for the other person.  Such respect was essential because that old technology permitted only one person to speak at a time.  There was no point in my trying to shout down the other person - to do so only resulted in my own over-loud voice coming back at me.  

Imagine if today’s wireless systems were a single channel that required only one person to speak at a time!

Fortunately, technology has eliminated that communication bottleneck by providing two channels - one to talk on and one to listen on.  In today’s wireless systems, each of the two channels are on different frequencies and both parties can talk over the top of the other and actually be heard.  This compares to the old radios where there was only the one frequency and each party had to talk at different times.

The consequence of enabling both parties to talk at the same time is that our present wireless networks require twice as much radio spectrum.  For each mobile phone or WiFi conversation, twice as much bandwidth is required than the old radio systems. The same two-frequency requirement applies to broadband traffic.

In these days of burgeoning mobile broadband data, where demand will come to exceed capacities, the telcos are looking to new technologies to solve a serious problem.  There are technologies like 4G and LTE that seek to use the available spectrum more efficiently .  Other technologies, like picocells (mini mobile phone cells), will re-use the spectrum in ever-smaller local areas.  As great as these developments are, there still remains a natural limit to how much of our broadband can be sent via wireless means.

That limit has just doubled with the announcement last week of a new technology that still enables us to shout the other person down but requires only one frequency.  Developed by Rice University in the United States, the new technology is apparently low cost and can be implemented without disrupting existing services.  Because new wireless standards will have to be developed, this technology will probably not become commercially available until 5G (fifth generation) networks come on the market.

The doubling of capacity in our mobile broadband networks is an important consideration when it comes to the government selling down the ‘digital dividend’ 700MHz spectrum.  It doubles the value of that spectrum, which is not to say that the government will get $2Bn in the auction processes expected in 2012.  More importantly, this development doubles the capacity of the existing spectrum that our 3G and WiFi services use.

And so it gives weight to the argument that the 700MHz band be retained for fixed rural broadband infrastructure because the existing mobile broadband bands using 3G technology will last longer.  It reduces the economic imperative to allow mobile operators exclusive access to the band. The mobile operators want this spectrum primarily because it is cheaper to deploy services in than at higher frequencies.

As we move towards the “Internet of Things”, with upwards of 50 billion connected devices, this new full duplex technology can enable a win-win for both rural and mobile broadband users.  But only if the government allocate the digital dividend spectrum to rural fixed broadband use.