Wireless Waffle - A whole spectrum of radio related rubbish
Understanding Spectrum Liberalisationsignal strength
Saturday 21 November, 2015, 12:14 - Spectrum Management
Posted by Administrator
It's been a long time since Wireless Waffle reviewed a new book. That's largely because there are very few books published on the topic of spectrum management. But Lo! a new book has fallen across our desk. 'Understanding Spectrum Liberalisation' has been written by the trio of Martin Sims and Toby Youell (both journalists with PolicyTracker, a journal of the latest radio spectrum news) and Richard Womersley (who is a spectrum consultant with global spectrum experts LS telcom), all pictured below (for some reason in a Warholesque style).

sims youell womersley

understanding spectrum liberalisationSo what about the book itself? It's a surprisingly easy read, yet tackling some relatively complex topics. The authors take the view that the various mechanisms and methods based on 'liberalisation' that have tried to get spectrum from the tight-fisted hands of the regulators, into the free-spirited commercial environment, have either partly failed, or are destined to fail, and that the 'next generation' of spectrum management, which they consider to be sharing, will be the next fad to try and achieve the same thing.

The book is split into four parts:
  • Part 1: Setting the Scene - this section discusses what liberalisation was supposed to achieve, and provides a handy and simple to understand introduction to the technical issues that the reader needs to know in order to understand the rest of the book.
  • Part 2: Liberalisation in Action - discussed how liberalisation has been applied both in different sectors (e.g. broadcasting and satellite) and in technology terms (e.g. UWB and White-space).
  • Part 3: The Limits of Liberalisation - picks out examples of where the liberalised approach to spectrum management has not, maybe, had the positive outcomes expected and explains why this might be the case.
  • Part 4: The New Agenda - looks at some of the newer techniques being introduced such as Licensed Shared Access, 5G and Li-Fi, and suggests that it will require a combination of regulatory relaxation, technical innovation and commercial pressure for truly efficient spectrum use to be yielded.
The book is written in an informative yet informal style, for example:
The Swiss auction showed that the increasing complication [of auctions] could have disastrous consequences, rather like using a bullwhip to swat a fly on a friend's face - a very risky enterprise.

The book concludes with a section on how the ITU works (or doesn't work) and a handy glossary of a wide range of technical and policy terms that regularly crop up throughout the book.

A good read for anyone involved in radio spectrum management, especially those in a regulatory capability, or who have regular interactions with regulators or some of the bigger institutions and organisations that are shaping or defining spectrum policies.
add comment ( 32 views )   |  0 trackbacks   |  permalink   |   ( 3 / 5338 )

5 Guiding Principles for WRC-15signal strength
Saturday 31 October, 2015, 12:05 - Spectrum Management
Posted by Administrator
itulogoThis week in Geneva, the next in the series of ITU World Radiocommunication Conferences (WRC) begins. One of the most contentious items on the agenda at the 2015 WRC (WRC-15) is so called Agenda Item 1.1 (AI1.1). AI1.1 will address the identification of new bands for IMT-based mobile broadband services. Over the last 3 years, (since the last WRC) the amount of effort that has been put into estimating how much spectrum is required, identifying suitable bands, and conducting compatibility analyses to determine whether the use of these new bands are viable, is immense. And yet, the results remain inconclusive.Against this backdrop, the GSMA, the industry body which represents mobile operators, is eyeing four main frequency bands to be identified for more IMT services. These include:
  • The UHF television band (470 - 694 MHz)
  • Spectrum at L-band (1350 - 1518 MHz)
  • An aeronautical radar band (2700 - 2900 MHz) and
  • The satellite C-Band (3400 - 4200 MHz)
But the bands proposed by the GSMA for IMT are not 'empty', they have incumbent users who are occupying and making economically viable use of the frequencies, although this situation changes from country to country. Some countries may be able to use some of the proposed bands but others may not. There is not a 'one size fits all' answer, and taking sweeping international decisions for whole regions of the world may not lead to the best outcome. Excessive harmonisation can lead to inefficiencies. Consider the forced allocation of spectrum to maritime services in countries such as Afghanistan, Chad, Hungary, Nepal or Paraguay which have no coastline which would leave bands unused and unusable. But national footnotes can be equally damaging if they are not well thought through.

Identifying more spectrum for IMT could even lead to bigger headaches for administrations in trying to refarm incumbent users and may not lead to a more vibrant and efficient mobile industry. Balancing the World's interests with those of each country is what the WRC and its national delegations should seek to achieve. The optimum outcome is a result which achieves both. In this respect, Wireless Waffle presents...

5 Guiding Principles for those attending WRC-15


PRINCIPLE 1: Act in the national or regional interest
  • Ensure that the services are important to the development of your country are protected.
  • Determine which of these are needed to encourage social and economic growth.
  • Understand your national priorities - more spectrum for IMT or other services such as broadcasting, transport or government services.
shakespearePRINCIPLE 2: Don't be bullied into taking decisions
  • Question the motives of those making bold statements - are they acting in your interest or just their own?
  • Remember that the long-term needs of mobile operators are at best unclear or undefined, and may well be overstated.
  • Consider that "An empty vessel makes the loudest sound" - William Shakespeare
PRINCIPLE 3: Make sure you see the bigger picture
  • Check all the facts that are presented - 81% of statistics are made-up.
  • Make sure you fully understand all sides of the argument - who stands to win and who stands to lose.
  • Understand the implications of any decisions you make - both today and longer-term.
PRINCIPLE 4: Don't assume that more IMT spectrum means more government income
  • Many mobile operators no longer 'want' new spectrum as they have not used that which they already have.
  • 4G (and 5G) spectrum are of no use in countries where data usage remains very low - in these countries 3G - in existing bands - is far more cost effective.

PRINCIPLE 5: Work with your existing mobile operators to allow them to do their best
  • Work at licensing more of the already identified IMT spectrum.
  • Check that your operators are using their spectrum efficiently. If they're not, how can they demand more?
If every administration attending the conference followed these simple yet effective principles, the outcome of the WRC should be both fair and equitable to everyone.

Whatever the outcome is, let us at Wireless Waffle end by saying 'Bon Chance mes amies'!
add comment ( 179 views )   |  0 trackbacks   |  permalink   |   ( 2.9 / 210 )

LEO: Roaring in the wrong direction?signal strength
Wednesday 23 September, 2015, 12:36 - Satellites
Posted by Administrator
wireless waffle ferretOn several previous occasions, Wireless Waffle has discussed some of the problems, both technical and economic that the raft of companies planning to launch new constellations of high throughput, broadband delivering, satellites may face in making their services a success. Whilst ferreting around the internet, it was interesting to discover a paper entitled 'LEO: Roar or Whimper' which discussed many of the same issues on which Wireless Waffle has opined in the past.

The paper, however, takes a more sideways approach and compares the situation facing new operators such as WorldVu and SpaceX who are intending to launch literally thousands of satellites to provide broadband services, with satellite broadband networks that were planned to do just the same thing in the 1990s (such as Teledesic and Skybridge) but which never got off the ground (so to speak).

leo roar or whimperIt turns out that many of the potential hazards facing today's planned satellite networks have changed little since the 1990s and in some cases the situation may have gotten worse. Take for example the amount of space debris now hanging around at various orbits which is much greater than it was 20 years ago. And though the technology has moved on, the costs of implementing complex satellite earth stations that can track the satellites are no less soluble today than they where when the Spice Girls were topping the charts, even with the advent of leading-edge technologies such as meta-materials. There are a range of other issues discussed in the paper which seems to consider the landscape for the LEO networks to be relatively bleak and foreboding despite many big name investors backing these projects.

For what it's worth, the Wireless Waffle answer to the question posed in the paper's title, 'LEO: Roar or Whimper', is that it seems that the LEOs will roar, but quite possibly directing their volume at people who are wearing noise cancelling headphones and thus won't hear their bellowing cry. Metaphorically speaking!
add comment ( 111 views )   |  0 trackbacks   |  permalink   |   ( 3 / 5581 )

Is WiFi hazardous to health?signal strength
Monday 31 August, 2015, 14:13 - Spectrum Management
Posted by Administrator
A number of people claim that they have had adverse medical and psychological responses to the presence of WiFi signals. But can WiFi actually constitute a health hazard? Wireless Waffle investigates...

Let's begin by considering the international rules which establish the limits for which exposure to radio signals is deemed to be detrimental to health as defined by the International Commission on Non-Ionising Radiation Protection (ICNIRP for short). ICNIRP has established a set of limits for the general public which are designed to stop the temperature of an average human body rising by more than 1 degree Centigrade over a roughly 24 hour period. This level of exposure is 50 times below that at which any measurable biological effects on humans have been identified.

These limits, measured in terms of the measured electrical field strength in Volts per metre, are shown below over a range of different frequencies.

icnirp general public

But what do they mean in practice and how does this help calculate whether WiFi could be dangerous. A WiFi transmitter, operating at full power (100 milliWatts, or 0.1 Watts) that is 2 metres (or 6 feet) away, produces an electrical field strength of just over 1 Volt per metre. The threshold of danger at the frequency that WiFi operates - 2450 MHz - is 61 Volts per metre and so at just 2 metres distant, the signal from a WiFi device is 61 times below the safety limit.

laws of physicsThere is another, and maybe more straightforward, way to calculate whether or not a radio transmission is likely to be dangerous. According to the laws of physics (which as everyone knows, canna be changed) 1 Watt of power (equivalent to 1 Joule per second) will raise the temperature of 1 gram (or 1 ml) of water by 1 degree Centigrade in 1 second assuming that all of the power can be focussed into the water. This is effectively how microwave ovens work: radio energy is focussed into the water in whatever is being cooked, heating it up.

If, for the sake of argument, we make the assumption that an 'average' human being weighs 50 kg (110 lb), and that it is made largely of water, it would take 50,000 Watts (or 50 kW) of energy to raise their temperature by 1 degree Centigrade in 1 second. To do the same job over the 24 hour period defined by ICNIRP would require 86,400 times less (60 x 60 x 24) meaning that if our average human absorbed around 0.6 Watts of energy for a 24 hour period, this would be deemed to be unsafe. WiFi transmitters have a maximum transmitter power (limited by law) of 0.1 Watts, which is below this limit. So even if ALL of the power transmitted by a WiFi device were absorbed by a human for 24 hours, it would still be a factor of 6 times lower than the ICNIRP safety limit.

In reality, it would be impossible to absorb all of the power from a WiFi transmitter unless that transmitter was inside the human body. Even if the antenna was placed directly on the skin, as signals from a WiFi transmitter are sent out equally in all directions at least half of the power would radiate away from the body, further reducing the impact on the human concerned.

swallow antennaIf the WiFi transmitter is 2 metres away, the signal from the WiFi antenna will have spread out so much that far less than a tenth of the original signal would wash over the body of a human, putting the exposure at a factor 60 times below the ICNIRP limit - gratifyingly the same as the level of exposure calculated using the graph above.

It is also worth noting that WiFi transmitters do not transmit constantly. At their busiest, they transmit around 50% of the time (they spend the other 50% of the time listening for incoming transmissions). Any exposure will therefore be another factor of 2 times smaller than above.

So what is the conclusion? As long as you don't swallow 6 transmitting WiFi antennas that continue to transmit on full power for a 24 hour period, any radiation from WiFi transmitters is far, far (far) below the established safety limits.
add comment ( 488 views )   |  0 trackbacks   |  permalink   |   ( 3 / 5604 )


| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | Next> Last>>