Comment: The challenge of mobile data

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Comment: The challenge of mobile data

Nobody wants towers, everybody wants coverage.


 The desire for more data on the go faces dual challenges of spectrum availability and infrastructure requirements. David Havyatt forecasts our mobile future.

Telecommunications regulator the ACMA is responding to the growing demand for data services on mobile devices, identifying a need for an additional 150 MHz of spectrum by 2020. 

But more services and more spectrum also means more infrastructure. 

After a long lull, local communities are again getting agitated by new infrastructure, as detailed by a series of reports by iTnews' Ry Crozier.

Partly the additional infrastructure is being driven by existing spectrum shortages and the need to make cell sizes smaller. But additional spectrum doesn’t necessarily solve the problem. 

The new spectrum is at different frequencies and will be mostly using different technology.  Different technology can mean that the services simply can’t share an antenna because they use different multiplexing techniques.  Even with the same technology, antennae are “tuned” to the frequency they use and separate antenna may be required for efficiency.

Even if that can be overcome, the different propagation characteristics often require different cell spacing for different frequencies.

What’s the problem?

Mobile service providers and policy makers often struggle to understand why communities that want better service reject the infrastructure necessary to provide it.

Ultimately there are two environmental concerns; a concern about health effects and a concern about visual pollution. The two can sometimes interact.

The health concern is a natural fear of the “unknown” tinged with a distrust of corporations, fuelled by examples such as the tobacco and asbestos industries.  To this has been added the recent IARC classification of radiofrequency electromagnetic fields as possibly carcinogenic to humans.

There is however a very big difference. In both the tobacco and asbestos cases, the goods were known carcinogens while still being denied by industry.

The IARC conclusion is also misunderstood; the detailed report specifically related to the effect of devices held close to the head, not of infrastructure.  It also relates to all “radiofrequencies”: that is 300 kHz to 300 GHz. 

These bands are also generally referred to as microwave. The heating effect of microwaves is well known and covers the whole band. It works on water because water molecules are dipoles (you may have seen the experiment bending water from a tap with a static charge). This means any radio or microwave makes them vibrate – and hence increase temperature.

We’ve been exposed to environmental RF for nearly eighty years from AM radio, and over fifty years from television.  People have got more agitated about mobiles because of the “microwave” component and the idea that mobile spectrum is more like what we use to heat food.

The specific frequency used in microwave ovens – 2.4 GHz –is the Industrial Scientific and Medical (ISM) band that is class licenced (referred to incorrectly as unlicenced).  That’s kind of strange because they are designed to ensure no leakage.  But that’s the same band used for garage door openers, most cordless phones and WiFi networks. 

The mobile networks use a number of frequencies – the lower ones being closer to TV frequencies than they are to ovens.  Somewhere along the line the interference caused by the GSM signalling also got people excited about the radio in mobiles being “pulsating”.

Handsets and infrastructure

Unlike TV and radio, the designers of mobile networks want to keep power levels down so as not to create interference in the next cell. 

The possible risk from mobiles comes at the handset end; and concern about possible health effects here is actually a good reason for building more base stations, not less. Handsets use adaptive power, they use only as much power as they need. The power emitted close to the user is therefore lower with more transmitters in the field.

So the real problem with building more infrastructure is that it is ugly.  Attempts to conceal it are often interpreted as attempts to hide it; and this feeds into the health concerns and is seen as just another typical act of uncaring corporations. 

There are a range of things that could be done to improve the environmental impact. 

The first is to redesign some existing facilities.  The old headframe with three antennas in each direction is no longer required – modern infrastructure uses one in each direction. 

The second is to get more effective spectrum planning.  If each operator has a bigger chunk in one band then you need less multiple antennas per site. 

The third will be new antenna and infrastructure design.  Alcatel- Lucent has begun promoting its “light radio” which is fibre-fed complete base-station technology in a devices the size of a Rubik’s cube.  This promises a complete redesign of mobile infrastructure. 

The challenge for Government and industry is how to respond to community concerns.  One thing is certain, the IARC will never move to downgrade the cancer rating of non-iodizing radiation.  It is always going to be listed as “possible.” 

That means industry needs a solution that reduces visual impact while also reducing required handset power.

It may be too early yet to call for an NBN of wireless as the best solution. The Government may need to recognise that industry has little commercial incentive to go back and refit many of the existing transmission sites.

When last the community was outraged it was over the deployment of the One.Tel network.  Approaches by Parliamentary Secretary Ian Campbell got the industry to focus on the need for change.  From that the Mobile Carriers Forum was formed and a lot of work on co-siting, community consultation and EME modelling occurred.

Doing more of what we do now will not sustain us for the next big wave of network building following the 2.5 GHz and 700 MHz auctions in 2012.

Do you have an example of unsightly mobile infrastructure you want to share?

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