Wireless Waffle - A whole spectrum of radio related rubbish
Digital UK Magic Spectrum from Nowheresignal strength
Tuesday 21 November, 2017, 10:27 - Broadcasting, Licensed, Spectrum Management
Posted by Administrator
digital uk nov 2017Digital UK, the organisation responsible for promoting digital terrestrial television in the UK, has recently published a white paper it commissioned from consultants Aetha and Webb Search entitled 'The defragmentation dividend: A more efficient use of the UHF band'. The paper hypothesises that by re-organising the UHF (e.g. sub 1 GHz) spectrum available to mobile operators, it would be possible to use it more efficiently and deliver more service from the same amount of spectrum.

The paper identifies the fact that, at present, the 'digital dividend' spectrum (e.g. that which has been released from television broadcasting due to the increased efficiency of digital transmission over its old analogue counterpart), is broken up into a number of fragmented pieces whose usage is not optimum. This is certainly true: the figure below shows the current set of allocations within the frequency range 694 - 960 MHz.

694 960 mhz plan

The mobile allocations at present are as follows:

BandUplink (MHz)Downlink (MHz)Amount (MHz)Notes
900 MHz876-915921-96078Including GSM-R
800 MHz832-862791-82160
700 MHz (a)703-733758-78860FDD
700 MHz (b)738-75315TDD or Downlink
TOTAL213

In addition there is approximately 29 MHz set-aside for short-range devices. Thus, of the total of 266 MHz of spectrum between 694 and 960 MHz, 213 MHz (80%) is allocated to mobile services, 29 MHz (11%) for short-range devices leaving 24 MHz (9%) 'empty' (mostly for guard-bands to protect services on adjacent frequencies from interfering with each other). The theory is that by re-arranging the band, it is possible to use all of the small gaps that currently exist between the various mobile allocations (e.g. the 9% that is empty) for more mobile services.

One of the problems of the plans proposed in the report is that although they increase the amount of spectrum for mobile services to up to 250 MHz in their most extreme case, they also reduce the amount available for short-range devices from 29 MHz to just 16 MHz. Whilst you may be thinking, "isn't mobile a better use of spectrum than short-range devices", the fact is that an increasingly wide ecosystem of devices is supported in this spectrum. It includes radiomicrophones and wireless headphones but perhaps even more critically, a growing number of Internet of Things (IoT) technologies that are seen by many as being at the centre of the next stages in the development of the Internet. This includes sensors (e.g. thermostats, light sensors), smart meters (electricity, gas and water) and a wide range of smart-city applications such as transport management. Digital UK's proposed plans involve changing the frequencies used by these devices, which is notoriously difficult. How long, for example, do the keyfobs that unlock your car door last - as long as the vehicle itself in most cases. So clearing a short-range device frequency won't be completed until every device in a band has been replaced by a new one.

The report only pays passing comment to the new 600 MHz mobile band that is being implemented in the USA. In fact, the report seems to suggest that even its most conservative re-organisation option would release so much capacity that there would be no need for the 600 MHz band:
...even the more modest increase of 25% in Option 1 would be similar to the capacity that could be provided by repurposing the 600MHz band...

mobile uplink downlinkIt makes this claim as a result of an oddity of current mobile technology, in which the amount of spectrum (and capacity) that is available to a mobile user is roughly equally split in the uplink and downlink directions (e.g. to the network from the user, and from the network to the user respectively). If the band was re-purposed as Time Division Duplex (TDD), the share of uplink and downlink capacity can be changed, and the report assumes that 80% of overall capacity would be made available for downlink and 20% for uplink (this is in fact in line with current estimates of the real split of usage). If this is the crux of the argument, then doing nothing at all to actually change the overall amount of mobile capacity available, but changing all of the existing allocations to TDD would approximately yield a 60% 'improvement' in downlink capacity, but this would be to the loss of uplink capacity which would fall by 250%! There is no gain without pain. In addition, TDD operators in adjacent mobile spectrum need to fully synchronise their networks otherwise there needs to be a guard-band between them, reducing the overall efficiency of use and opening up new gaps.

Whilst the report makes a valid argument about whether the future of mobile should be TDD or FDD, it is perhaps no surprise that it chooses this solution to theorise about an improvement in the efficiency of use of UHF spectrum, over and above the use of the new 600 MHz band, whose use would obviously entail the loss of (yet) more spectrum for digital terrestrial television. Sadly for Digital UK, the required pain, in terms of re-organising existing mobile networks, and replacing all short-range devices is sadly never going to counterbalance the gain of a few extra MHz of UHF spectrum.
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The Five G's...signal strength
Friday 22 September, 2017, 09:12 - Spectrum Management, Much Ado About Nothing
Posted by Administrator
the 5 gees 5gWhilst much of the world is yet to experience the joy of 4G (LTE) mobile technology, work is ongoing in a variety of prestigious international bodies to put the finishing touches to the specifications for the next generation of mobile technology: 5G. Everybody knows that 4G stands for GGGG, or the stuttering noise you get when buffering a video, but what are the five G's? Simple, it's Girls, Goals, Gambling, Gaming and videos of Grimalkins, which are the cornerstones upon which mobile technologies aim to make their fortune.

Slightly more seriously though, oodles is already beginning to be written about what 5G will deliver, which includes a range of features such as:
  • Blazing hot, super, ultra, mega-fast broadband internet.
  • Ubiquitous, go-everywhere, global, universal coverage (even in those hard to get at areas such as behind the sofa).
  • Instantaneous, low-latency, tactile, real-time connectivity.
  • Extremely high reliability, such that the network will only be down for 14 seconds per millennium, which together with low-latency mentioned above, is termed Ultra-Reliable Low Latency Communications (URLLC).
  • Capacity to connect thousands of billions of machines (such as coke vending machines and tumble dryers) known as Massive Machine Type Communication (MTC).
  • Power consumption so low that batteries only need re-charging once in every 4 years and base stations can run on one lemon per month.
  • World peace and an end to global poverty and disease (this might be made up).
There are many visions of 5G but they all tend to have a common theme of apparently perfect connectivity where any person or device can connect wherever they are, at whatever data rates they wish, and with minimal latency. There is no doubt that 5G will achieve some, maybe all, of these goals, but probably not all at the same time or in the same place. The only (well one of the only) problem(s) with this, is that it needs hundreds, if not thousands, of MHz of valuable radio spectrum and a tenfold increase in the number of cell sites to achieve these goals.

5G is being touted as the 'mobile technology to end all mobile technologies' and as a panacea for all ailments. This miraculous technology will provide what some have termed an 'always sufficient connection' which gives the impression of infinite bandwidth - yes, infinite.

A recent study for the European Commission entitled 'Identification and quantification of key socio-economic data to support strategic planning for the introduction of 5G in Europe' claims that 5G will bring over 110 billion of benefits per year by 2025 across just four industries: automotive, health, transport and utilities (i.e. ignoring the benefits to you or I of coverage behind the sofa). Others, however, have cast doubt on the claims of the 5G community. Professor William Webb has published a book entitled 'The 5G Myth'. In it, he raises a number of concerns about 5G's ability to deliver the enormous range of benefits it is promising, and the associated drive for more radio spectrum for mobile services. Professor Webb's arguments which are largely about the ability or willingness of mobile operators to pay for the necessary investment in 5G includet:
  • Mobile subscriber numbers have levelled off and average revenue per user (ARPU) is in gentle decline.
  • The 5G vision has not been coupled with a business case. The business reality is that there is no new money.
  • The business case for the 'jewel in the crown' of 5G its millimeter Wave (mmWave) solution makes little sense.
He goes on to make a number of recommendations about what those in charge of radio spectrum and telecommnunications regulation should be doing:
  • Regulators and the ITU should not focus on spectrum for 5G - instead they should ensure that spectrum is available for each component [e.g. broadband, critical communications and IoT].
  • Academics should have a stronger links to business departments in universities to ensure that technical breakthroughs are actually valuable.
  • Large players (e.g. Ericsson, Nokia, Qualcomm, Huawei, Cisco and Google) should stop believing that the future is all about Gbit/s data rates.
  • Governments should focus on deployment, applications and over-the-top (OTT) services not just spectrum.
happy 4 g stringWhat is odd about both sides of the argument, is that many of the so-called advantages of 5G can almost certainly be delivered by 4G (LTE), especially by the forthcoming super-4G variant known as LTE-Advanced-PRO (3GPP LTE Release 13 and 14) - often termed 4.9G. All that 5G really brings is an explosion in the number of cell sites (which could occur using 4G) and technologies and techniques to allow access to new mmWave spectrum above 24 GHz which, according to Verizon may not be great for mobile services anyway:
Delivering mmWave broadband connectivity in non-line-of-sight environments, such as suburban and urban areas, is extremely problematic over the last quarter mile, because of foliage and solid constructions.

The European Commission believes that 5G is important. Its 5G Action Plan encourages each and every Member State to have a 5G service in at least one city in their country by 2020. Whether this could be delivered using 4.9G to the satisfaction of the Commission is not clear but Ericsson's definition of a 5G subscription in its Mobility Report is:
a device capable of supporting LTE Evolved or NX, connected to a 5G-enabled network, supporting new use cases

This is effectively saying that 4.9G LTE-Advanced-PRO connections would be considered as 5G subscriptions.

The reality is that the real 5G specifications will not be completed until 2020, hence any service delivered before that date can be a 'pre-5G' service at best - or maybe 4.9G. Plans for 5G services in each EU Member state, at the Winter Olympic Games in Korea in 2018 and the Tokyo Olympic Games in 2020 can only possibly fall into the pre-5G category as there will be no agreed 5G standard by these dates.

That being said, there was a time when the World was awash with 'pre-N' internet routers, which were built before the relevant standard (IEEE 802.11n) was completed. The issue with such pre-standardisation products is generally one of interoperability. Each manufacture would have had to have implemented a variation of the standard as they thought it would be finally ratified and these may have been different. Thus whilst a pre-N Netgear router may have worked with a pre-N Netgear WiFi dongle, it wasn't guaranteed to work with a TP-Link, Belkin or a Linksys one.

pre n router resultsFor WiFi, that's probably not such a big problem, not least as if the 'N' connection failed, the router and dongle could fall back to an agreed, but less whizzy standard such as 802.11g and thus whilst the benefits of the newer standard wouldn't be realised, the WiFi would still work.

This may be what happens with the pre-5G mobile networks. Japan, for example, has a number of domestic mobile phone manufacturers (e.g. Sony, Sharp, Panasonic) who could agree to make pre-5G phones to whichever standard the Japanese mobile operators chose to roll-out. But for anyone else visiting the country (e.g. for the 2020 Olympic Games) with phones made by other manufacturers, they would just fall back to 4G and not enjoy the benefits of 5G. In such a way, Japan could claim to be offering a 5G service, but it would not be one that was internationally compatible.

So whilst 5G may yet save the world, it is unlikely to do so by 2020 unless you happen to live in a country which has its own mobile manufacturers, live in one of the minute areas where coverage will exist, happen to be there on a day when the 5G service is actually working, and have bought a locally produced 5G phone (or have been provided with one as a guinea pig to test the service). For the rest of us, its going to be more like 2023 or 2025 before real 5G services begin to make a difference to our daily lives and the (perfectly adequate) 4G service we already enjoy will, for now, have to be largely sufficient (though this doesn't make such a compelling strap-line for mobile operators' marketing departments).

largely sufficient
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Tune In, Light Up!signal strength
Thursday 27 July, 2017, 14:56 - Radio Randomness, Spectrum Management
Posted by Administrator
Wireless Waffle recently suggested that the high power short-wave transmissions coming from the HAARP site in Alaska were trying to trigger lightning strikes in an attempt to send radio signals strong enough to be received on a remote planet.

airglow flashlightIt seems that they are not the only ones who are generating very high power short-wave transmissions, but that the enormous dish at Arecibo in Puerto Rico has also been turned into a giant transmitter. Experiments taking place right now (from 24 to 31 July 2017) involve transmissions around either 5.125 or 8.175 MHz (the most recent transmissions have been on 5.095 MHz) with an effective radiated power of around 100 MW (MegaWatts).

The purpose of the transmissions is to try and heat up the ionosphere for various experiments, including trying to establish Langmuir waves which excite oxygen atoms sufficiently that they emit light at visible wavelengths and light up the night sky in something known as 'airglow'. You couldn't make this stuff up!

Those strange lights in the night sky that you thought were UFOs... it's just scientists getting their oxygen atoms all excited. Nothing to worry about.
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A Jovial Receptionsignal strength
Wednesday 29 March, 2017, 09:15 - Radio Randomness, Spectrum Management
Posted by Administrator
Wireless Waffle has previously discussed the idea that it might be possible to receive radio transmissions from alien planets, but it might not be widely recognised that it is possible to receive radio transmissions from planets within our very own solar system!

mobile phone on jupiterIt turns out that the planet Jupiter emits a range of different radio transmissions, not from people using mobile phones on the planet's surface, but so called long 'L' bursts and short 'S' bursts which are generated by the planet itself and its interaction with its moons, and that these signals are relatively easy to receive here on good old planet Earth. These emissions range in frequency from a few kHz to around 40 MHz. The Jovian signals get weaker the higher in frequency you go, but the lower frequencies are often absorbed by the Earth's ionosphere. In addition, many of these frequencies can be replete with short-wave transmissions. What is needed, therefore, is a frequency that is high enough to pass relatively unperturbed through the ionosphere, but low enough to be receiveable, without too much interference.

An obvious place to start would be the Radio Astronomy frequency allocation between 25.55 and 25.67 MHz as these frequencies should theoretically be free of all other radio transmissions. But it seems the frequency of preference for catching the latest bursts from Jupiter is actually 20.1 MHz, which is the frequency selected by NASA's Radio Jove project. From a radio spectrum perspective this is a relatively odd choice of frequency (e.g compared to the theoretically clean Radio Astronomy allocation). At an international level, frequencies around 20.1 MHz are allocated primarily to the fixed service, with a secondary allocation to mobile services. A quick scan of the Globaltuners database shows AT&T usage on 20.095 MHz and US Civil Air Patrol on 20.107 MHz. However, it seems that the signals from Jupiter at higher frequencies are much weaker, even by the time 25 MHz is reached.

radio jove antennaSo what do you need to listen to these mysterious signals? A simple short-wave radio should do the job, however it is said that there are two additional things which need to be done in order to tune in to Jupiter:
  • Turn off the AGC (automatic gain control) on the receiver. The AGC apparently tends to mask the bursts. A software radio is ideal for this.
  • Build a simple directional antenna.

The latter of these is the most difficult. A two-element array is what the experts say is needed, and at 20 MHz, this is roughly 8 metres (26 feet) square as the diagram on the right shows.

Notwithstanding a lack of the correct antenna, Wireless Waffle sought to attempt to receive Jovian radio signals using a short-wave receiver and a normal short-wave antenna (not the fancy two-element arrangement). Sadly, our attempts did not yield any L or S bursts that could be definitively identified as transmissions from Jupiter. We did however manage to receive:http   allbum it  ash girl from mars remixSo though we failed to receive any Jovian signals, we did receive some jovial ones and therefore maybe it wasn't such a pointless exercise as at first it might have seemed! Why not give it a go yourself and let us know how you get on?
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