Cell Phones, Wi-Fi, and Electromagnetic Radiation

All radio devices like cellphones, radios, televisions, and Wi-Fi devices communicate via electromagnetic radiation. These man-made devices are not the only source of such radiation – the Earth’s magnetic field, the Ionosphere, the sun, and the universe in general all emit similar electromagnetic radiation, over an extremely broad range of frequencies.

Electromagnetic radiation, which can be invisible like radio waves, visible like light, or felt like infrared heat, is subject to a law of physics called inverse-square. The quantity or intensity of any radiation is inversely proportional to the square of the distance from its source. The diagram below illustrates this principle.

Creative Commons licensed Image courtesy of Wikimedia user Borb



Just like when sitting around a fire, the closer a person is to the source of some radiation, the more exposure they will receive. The further away, the less exposure.

Levels of radiation from devices as absorbed by the body are measured with a standard called the “Specific Absorption Rate”, or SAR, which is a calculation of the energy absorbed by a person in watts per kilogram. In New Zealand, NZS 2772.1:1999 regulates a maximum permitted exposure of 2W/kg. (updated link 5 Jan 2014)

Online news provider CNet tests the SAR of mobile phones on a regular basis and stores the results in a database, which was last updated in July 2013. The mean score of their top 20 lowest radiation phones is .32, and the mean of their top 20 highest radiation phones is 1.43.

While cellular towers emit much higher power levels than cell phones, due to the inverse square law the amount of energy a person can absorb from them can be quite low. At ten meters, about as close as a person can get to a cellular antenna, the SAR of a 50 Watt GSM transmitter is .365, or just around the level of one of the lowest radiation cell phones on the market.

Such cellular tower radiation levels have been judged by the Environment Court (Shirley Primary School v Christchurch City Council C136/98) to be so low that the risk of radiation to students from a cell tower to cause sleep disorders or learning disabilities would be “in the order of one in a million”, and that “there was so little evidence for an adverse health effect from RF emissions that it cannot be scientifically calculated as a percentage probability in small fractions of a percent”.

Wi-Fi devices operate on power levels far lower than cell phone towers or Smartphones. While a cellular tower may emit 50 watts, a Wi-Fi router is restricted to 4 Watts or 1 Watt, depending on the frequency band in use. A recent study by the UK National Radiological Protection Board found that for a child in good signal range of a wireless router, the SAR at head level was 0.0057W/kg.

The table below summarises the various data:

[table id=1 /]

With 5,407,000 mobile subscriptions as of 2012, New Zealand has more active cellular connections than people. Many of these connections, including all of Telecom’s nearly two million, are 3G connections that support data alongside voice. Smartphones were in the hands of 44% of subscribers by 2012, and most of those subscribers use data on them every day. Smartphones also make up 58% of all new phones sold today.

One of the most common features of Smartphones is the ability to use data on Wi-Fi networks. When using Wi-Fi, the power levels absorbed by a user of a smartphone will be far lower than if the device is using 3G.

From the research cited above, it’s clear that if you’re going to use a Smartphone or allow one to be used near you, the best way to minimise radiation levels is to ensure that Smartphone is using a Wi-Fi hotspot for its data. Calling for the elimination of Wi-Fi from public places or schools on the basis of a radiation hazard is entirely misguided and counterproductive to a goal of lessening absorbed radiation.

NZ Radio Spectrum Landscape 2013

2012 brought significant change to New Zealand’s spectrum landscape in the form of multiple transactions involving radio spectrum management rights.

First, Vodafone and CallPlus entered in to a spectrum swap, converting two TDD blocks in the 2.5GHz range to FDD blocks compatible with UMTS Band VII.

Then Vodafone purchased TelstraClear, who held 150MHz of spectrum worth nearly $100 million dollars. As holding such a concentration of spectrum to the detriment of smaller players could be seen as a misuse of market power, Vodafone chose to leave some spectrum on the table in that deal. Telstra Australia then sold a 15MHz pair in Band III to 2Degrees shareholder Trilogy, and has kept a 5MHz pair in UMTS Band I.

The resulting spectrum landscape, detailed in the graphic below and in a downloadable wall chart, has increased the ability of both Vodafone and 2Degrees to deliver new and better services to New Zealand consumers.

In the chart, holdings of Telecom are shaded yellow, Vodafone orange, and 2degrees (including shareholders Hautaki and Trilogy) blue. The 700MHz Digital Dividend band likely to be auctioned in 2013 is shaded green. Common 3G/LTE cellular bands are noted to the right of relevant cellular holdings.

Download an A-series PDF wall chart for printing or easier on-screen viewing.

Spectrum Infographic Tall 2013-04-03 copy

Cognitive Radio Should Be Priority #1 for RSM

RE: Consultation Draft – Radio Spectrum Five Year Outlook 2012-2016

Dear Minister,

I agree with the government’s goal of growing New Zealand’s economy and I am glad a link between effective radio spectrum management and New Zealand’s prosperity has been made in the introduction to MBIE’s Radio Spectrum Five Year Outlook 2012-2016.

Five years is a long time in the world of technology. In June of 2007, just five years ago, the first iPhone was released. The iPhone and its competitors have changed forever the way people interact with their phones and mobile data. This year, 3G smartphones are used by 50% of New Zealanders. Smartphones are poised to have a tremendous impact on New Zealand’s economy, with huge potential to streamline communications in the agriculture and tourism sectors.

In 2007 the most recent IEEE standards for 802.11 Wi-Fi allowed speeds up to 54mbps. This year the first 802.11ac Wi-Fi chipsets shipped to customers, at 867mbps. Due to light regulations and scarcity of spectrum, Wi-Fi devices are best in class when it comes to spectral efficiency and interference rejection, while having a lower cost per chipset than 3g/4g competitors. Wi-Fi is a part of almost every mobile device on the market, and is used daily at home and across all key industries. In the last five years, Wi-Fi has had an unquestionable impact on New Zealand’s economy.

Five years has brought New Zealand a new mobile carrier, but one who operates with a fraction of the spectrum tied up by incumbent carriers, not all of whom use their spectrum. As a result of the entry of 2Degrees, the cost of mobile services has dropped precipitously, and New Zealand consumers and businesses are reaping the advantages of affordable mobility.

Smartphones, Wi-Fi, and a third cellular carrier have emerged notwithstanding Radio Spectrum Management policies, legislation or changes to those over the past five years. They have developed within the bounds of very small blocks of radio spectrum when compared to traditional uses such as radio and television uses. They have shown that they are extremely efficient users of the spectrum, but all would benefit from access to more spectrum, and more effective spectrum management.

Measurements taken by University of Auckland researchers Chiang, Rowe, & Sowerby (2007) showed that in Auckland, arguably New Zealand’s busiest radio spectrum environment, real spectrum use in 806-2750MHz was only 6.2%. These measurements included all of the cellular and most popular broadband bands. Almost 94% of the New Zealand’s most valuable radio spectrum was quiet it its largest market. This is hardly effective management.

Taken in isolation, the UoA study might seem fantastic or flawed. Viewed in the context of studies around the world including the US and Singapore, some funded by the United States Defence Advanced Research Projects Agency, these measurements are unsurprising. It has been conclusively proven that traditional management techniques do not result in effective use of the radio spectrum.

Tradition, unfortunately, originates from New Zealand.

New Zealand’s pioneering approach to treat spectrum as a property right (based on the Torrens land title system) was based on a 1988 report by London consultancy NERA. Their work in turn was highly influenced by the ideas of Ronald Coase, who in a 1959 paper equated spectrum use to land use, and considered that users who would pay the most for exclusive rights to spectrum would put that spectrum to the best use.

It is unlikely that Coase or Charles Jackson, a key NERA consultant involved in writing the report, envisioned that treating spectrum as a property right would result in the massive inefficiencies we see in New Zealand today.

It has however happened. For a sum of money enough to block smaller competitors, some companies have locked up radio spectrum for years that would have a far greater impact on New Zealand’s economy if in use than the price they paid at auction. As a result of locking up the spectrum, these companies have been able to create an artificial scarcity. They have been able to use a limited amount of spectrum and equipment to provide services, while guaranteeing they were the only game in town. Resulting services and pricing, when compared to Australia or other OECD peers, has been poor for New Zealand.

The best result for the owner of the property has not aligned with growing New Zealand’s economy.

In the Five Year Outlook document, it’s stated that “the key operational objectives of spectrum management in New Zealand are to enable productive radio applications and minimise harmful interference between uses.” If this is the case, Radio Spectrum Management should be investigating ways of enabling productive radio applications as its highest priority – above asset management, documentation reviews, compliance projects, fee reviews, and above any legislative change that would further entrench the existing system of spectrum as an exclusive property right.

Section 4.1.3 of the Outlook document holds the key to efficient, productive, and full use of the radio spectrum. Cognitive radio technologies were created to take advantage of unused radio spectrum. They end the possibility of gaming the telecommunications market by purchasing and then not using radio spectrum. And while the Outlook assumes the technology is unlikely to develop within the next five years, the reality is cognitive radio is here and available today. Chipset manufacturers including Texas Instruments already offer DSP products capable of implementing cognitive radio (including IEEE 802 standards) and commercial cognitive radio networks are in use in the United States today.

The Outlook states of cognitive radio that “facilitation of the technology may require a radical departure from existing methods of spectrum regulation”. The time for a radical departure is now, and the concept that must be introduced to radio spectrum legislative and management frameworks is that of Primary and Secondary Use.

Primary Users have existing spectrum licenses which commonly allow for the right to transmit on a frequency and the right to have no harmful interference on that frequency. A primary user with a national management right could install transmitters around the country have interference-free operation everywhere they transmitted and everywhere their radio signals could reach. Their rights to offer a service would not be impeded upon.

Secondary Users are those with rights to transmit on frequencies only when their transmission would not affect a primary user, and with no protection from harmful interference on a particular frequency. Secondary Users can exist and thrive in areas where Primary Users cannot or will not, for either economic or technical reasons, use the spectrum they have licensed. Secondary use is an extremely good way of ensuring radio spectrum is used effectively.

The cognitive radio technologies now standardised by IEEE are advanced technologies that are capable of allowing safe coexistence of Primary and Secondary Users. They are likely to be adopted across all forms of radiocommunications, as innovative users meet with artificial spectrum shortages created by property rights based management and adapt to effectively communicate. In five years, cognitive radio products will not be an emerging technology, they will be a commonplace one.

The growth of New Zealand’s economy is linked to its ability to effectively communicate – not just with existing technologies, but with what’s next. Radio technology is changing faster than we can forecast on a five year time scale. We can’t reliably predict the next iPhone, Wi-Fi, or entrant into the New Zealand telecommunications market. We can predict that with so much of the world’s radio spectrum sold off but under-utilised, what’s next is likely to include cognitive radio.

The greatest impact Radio Spectrum Management could have on the economy is by ensuring management frameworks are ready for cognitive radio products. Such products will lead to greater, more efficient, lower cost communications, benefiting New Zealand in innumerable ways.

I thank you for this opportunity to comment on Radio Spectrum Management’s Consultation Draft – Radio Spectrum Five Year Outlook 2012-2016 and invite you to contact me if you have any questions regarding my submission.


Jonathan Brewer

Television White Space for Rural Wireless Broadband

This week Telco2 (publisher of NZTelco) has released an InternetNZ-funded study of the practical application of Television White Space Broadband for use in rural New Zealand communities.

Television White Space Broadband (TVWS) is an inexpensive, light weight technology – priced closer to wireless broadband equipment than it is to the cellular equipment typically used to cover rural and remote communities. Through its use of television spectrum TVWS can allow broadband coverage far more effectively than technologies like Wi-Fi while emitting just four watts of power – orders of magnitude less than a typical cellular tower.

Using the technology, wireless broadband providers are now able to take advantage of unused television spectrum, while the rights of broadcasters are preserved. In the most straightforward example of TVWS use, if a television broadcaster isn’t using their spectrum in a particular area, and if its use for broadband wouldn’t compromise a broadcast elsewhere, that spectrum is available for use delivering wireless broadband in a dynamic yet controlled way.

To evaluate the potential utility of TVWS in New Zealand, three rural communities that will be missed by the RBI were identified and evaluated. Radio coverage models were constructed simulating common, off the shelf Wi-Fi technology and new TVWS equipment. The models were then compared for coverage potential of each technology – with TVWS broadband showing a clear advantage in some situations.

The full report is available online: http://tinyurl.com/bph5amf from InternetNZ.

Kordia’s Strategic Review

Kordia are undergoing a strategic review as reported by Computerworld. It’s about time. Kordia could have been the shared infrastructure company of New Zealand’s wireless ecosystem – as dominant and profitable player as Chorus is set to be on the fixed line side of things.

Instead of sticking to its core business of maintaining towers and transmission to a high standard, Kordia attempted to grab everything it could. Gallingly, in almost all the cases of their numerous commercial failures, they went head to head with their existing infrastructure and wholesale services customers instead of cooperating with them. And they did so with appalling personal and organizational arrogance.

The bigger failures:

  • Metro Wi-Fi network that didn’t meet the needs of its users
  • Rural wireless product that had massive functional issues
  • Metro wireless Ethernet product that was expensive and based on dated technology
  • The KorKor network – inferior coverage to TeamTalk and inferior technology to Telecom’s XT.
  • AIS network – too little, too late, and too expensive for many harbourmasters and port companies
  • OptiKor – might have done well but since handed off to Axin, a secretive shell company hiding secretive inves* tors
  • A strident bid for the government’s Rural Broadband Initiative that had them partner with Woosh and FX, which featured unbelievable technological claims

Aside from DTV (and remind me who paid for that) where have they headed in the right direction?

  • Offshore contracts – bringing cash back to NZ. Nice work.
  • OnKor Wide Area Network Services – a technically excellent product taking advantage of fibre rights held from the Clear days and a microwave network built to move television broadcasts around – complimentary to Orcon
  • Odyssey – control international transit and you can provide QoS to your customers – nice long term partner to Orcon
  • Orcon – a real competitor in the market, but are Kordia committed to it long term?

Keeping in mind that Onkor and Orcon compete against Kordia’s wholesale clients, and Odyssey is most useful as a part of that ecosystem, here’s some strategy:

1. Package Orcon, OnKor, and Odyssey up & divest them. Stop competing with the best potential customers of your huge (and maybe overvalued) asset base.

2. Go to Vodafone, Telecom, & 2degrees, JDA, local councils, and other tower owners, hat in hand, and say “hey guys, we know we screwed this up a few years ago, but from now on how about we start working together on tower and transmission infrastructure. Oh, and LTE with its 700MHz rural towers and high density 2500MHz urban microcell requirements might be a great time to start”

That would be a good day for Kordia, and its owners, the people of New Zealand.