|Europe II 2013
|The new M2M paradigm and the Internet of Things
|Professor William Webb
Professor William Webb is the CTO of Neul, a company focusing on machine-to-machine communications using TV white-space spectrum. Dr Webb has been a key figure in shaping spectrum policy across Europe through his work at Ofcom, the UK Communications regulator. As Director of Technology Resources, William managed Ofcom research and development and led a number of key policy initiatives including the Spectrum Framework Review, the development of Spectrum Usage Rights and most recently cognitive or white space policy.
Professor Webb has published eleven books, eighty papers, and four patents. He is a Visiting Professor at Surrey University and DeMontfort University and a Fellow of the Royal Academy of Engineering, the IEEE and the IET where he is a Vice President. Dr William Webb has a first class honours degree in electronics, a PhD and an MBA
M2M is a technology whose time has come – almost. M2M is based upon communications, but almost none of the existing communications technologies is fully suitable for the majority of M2M applications. Weightless is a proprietary, royalty-free, open standard for wireless machine-to-machine communications using TV white-space spectrum. The standard was designed to minimise cost and power consumption, it uses a chipset costing less than US$2, and has a range of up to 10km and a battery life of 10 years.
You don’t have to be at the forefront of technology to have been touched by the fundamental shifts in the way we are globally embracing Smart Cities, Smart Grid, Smart Meters, Big Data, M2M and the Internet of things.
Today’s developments will continue to evolve way beyond what we can imagine today. But, at the start of 2013, it’s clear that we are already seeing themes and patterns coalesce and models being deployed to realise the visions that have been building over the last few years. 2013, more than any other, is set to be the year we will start seeing the promises unfold into reality. We will see the early evolution of true Smart Cities across the globe with almost every country in the developed world announcing plans for at least one and in many cases several. Even in the developing world we will see multiple examples and interpretations of what a Smart City is and what it means to its citizens and commerce.
Smart Grid and Smart Metering are high on the agenda of every utility company worldwide with the inevitable painful process of consumer acceptance dominating certain sectors of the media, right now in the US – a good indication that the technology has moved convincingly from the laboratory into the real world. All of these phenomena ultimately have one unifying factor. They require connection. Connections between the elements that make up the system whether they are a utility meter, a traffic light or a society are the key to making intelligent systems work. There might be a hundred nodes (or terminals or edges depending on your industry) in any system that needs to be connected to make it intelligent. Once the infrastructure to connect multiple elements is in place the number of connections will accelerate rapidly until everything is connected.
What is the technology that will enable these connections to take place and what will hold it together? One thing is for sure, it will be wireless. The sheer number of connections means that wired connections will simply not serve the needs of most systems and distance will often makes traditional LANs inappropriate. There are many short-range technologies that come closer to the prices needed for commercially feasible machine communications applications, including Wi-Fi, Bluetooth, ZigBee and others. These, however do not provide the range and coverage needed for applications such as automotive, sensors, asset tracking, healthcare and many more. Instead, they are restricted to machines connected within the home or office environments. Even in these environments a wide-area solution is often preferable. For example, an electricity supply company is unlikely to connect their meter via, a Wi-Fi home network; were the home owner to turn this network off, fail to pay for their broadband subscription or change the password on their home router, then connectivity could be lost. Restoring the connection could be slow and costly and maintaining security on a home network might also be difficult. Short range technologies are not the solution.
Optimal connection regimes
There’s the obvious network carrier – traditional telephony based cellular or GSM/3G/4G technology, and this is what many current machine communication solutions use – and it works. Sort of.
The M2M market has not reached its potential. The commercial opportunity is an order of magnitude greater than that of traditional telephony based cellular technologies. Tens of billions of devices are projected to be connected – an order of magnitude greater than that of cellphones. That’s more than ten per person on the planet and potentially worth more than a trillion dollars by 2020 – so what’s going wrong? Why isn’t the telephony model right for machine communications? There are several definitive and fundamental reasons: cost, power consumption and signal propagation characteristics.
Cost is absolutely critical in any system with some tens of billions of terminals. GSM and derivative technologies carry a significant cost throughout the value chain – the hardware cost at the terminal end alone is typically about US$20, depending on the cellular technology used. Subscription costs are about US$10 per month to amortize the cost of the network infrastructure. These costs are unsustainable for many applications.
Power consumption for a wireless device is frequently critical. It’s critical because by definition the device is remote, or at least not commercially feasible to attach to the grid. That gives rise to the need for, in virtually all cases, battery power and that makes power consumption a critical parameter. GSM based protocols are designed for a completely different regime and are ill-suited to the short message sizes in machine communications. They result in extremely significant overheads associated with signaling in order to move terminals from passive to active states, report on status and more. Additionally, GSM based technologies necessarily require sophisticated processing power at the terminal end of the link to provide for seamless handoff between cells, roaming and high bandwidth applications such as streaming video – and this comes at the expense of power consumption.
So while traditional GSM based technologies can capture a small percentage of the market it cannot meet the requirements of the 50 billion plus device market; if it could, it would have done so and there would be no further debate about the need for new standards.
Free spectrum is the game changer
A new option has emerged for spectrum access. This is the use of the white space spectrum – the unused portions of the spectrum band in and around TV transmissions. White space meets all of the requirements for M2M communications: it is unlicensed, so access is free; It is plentiful with 150MHz of spectrum available in most locations – more than the entire 3G cellular frequency band; it is globally harmonised – the same band is used for TV around the world; finally, it is in the perfect low frequency band which enables excellent propagation without inconveniently large antennas in the devices. White space is the paradigm shift; access to this spectrum provides the key input needed to make the deployment of a wide-area machine network economically feasible.
White space access requires specific network and terminal design characteristics in order to comply with stringent regulations. These call for interference free sharing of frequencies with the primary users of the spectrum, TV broadcasters and to a lesser extent, wireless microphone operators. Relatively low output power is specified, an order of magnitude lower than telephony based cellular technologies (GSM/2G/3G/LTE). The FCC has specified just four Watts for base stations and 100mWatts for terminals. Stringent adjacent channel emissions are specified. White space devices must not interfere with existing, primary users of the spectrum. The energy that they transmit must remain almost entirely within the channels that they are allowed to use. The FCC has specified that adjacent channel emission need to be 55dB lower than in-band emissions, a specification much tighter than most of today’s wireless technologies. And finally channels are allocated according to geographical location to further eliminate interference since different frequencies are used by TV transmitters in different locations. Devices must consult an over the air database to gain channel allocation data and to rapidly vacate a channel if it is needed by a licensed user.
Design rules for M2M
There are many benefits to the design of a standard specifically for machine communications. Machines are very different from people and the system design needs to accommodate these differences. Machine communications typically have a much shorter message size that human communications – with the exception of SMS text messages. Most machines only send a few bytes of information on a periodic basis whereas a human may download megabytes of information or transmit many sequential data packets for voice communications. Machines are more tolerant of delay – most are unaffected by a few seconds of delay whereas this would quickly become frustrating to humans. And finally machines have generally predictable communications patterns that send data at regular intervals and so can be pooled on these occasions. Human communications are typically unpredictable and, so, must often contend for access resources.
Systems made specifically for machine communications can be designed for much greater efficiency and offer greater capacity with lower cost and power consumption than would otherwise be the case.
Weightless is a proprietary, royalty-free, open standard for wireless machine-to-machine communications using TV white-space spectrum. The use of white-space spectrum, together with the unique characteristics of M2M traffic, compared to human traffic, means that the use of existing standards is far from optimal. The Weightless standard is optimised for this specific scenario and provides TDD (time-division-duplexing) operation with a wide range of provided data rates depending on the application, range and operating environment. The standard was designed to minimise cost and power consumption, featuring a chipset cost of less than US$2, a range of up to ten km and a battery life of ten years.