Why IoT needs a wide area wireless network
Machine communications, often termed the Internet of Things (IoT) or machine-to-machine (M2M), has long been forecast to be a sector with massive growth. Over the last few decades many have noted that the installation of a wireless connection into myriad devices would bring a range of benefits. An enormous range of examples have been suggested, from cars to sensors to traffic lights to healthcare applications and much more. More recent forecasts of 50 billion connected devices by 2020 do not sound so incredible when it is realised that this is only ten devices per person – many people already have more than ten wirelessly enabled devices in their home.
However, the market for machine communications to-date has been weak. There are some cars with embedded cellular modems and some relatively high-value items such as vending machines are equipped with cellular packet-data modems. But the market today is only a tiny fraction of the size it has long been predicted to grow to. This is predominantly due to the lack of a ubiquitous wireless standard that meets the needs of the vast majority of the machine market. These needs include:
- Low cost, both of the hardware and the service. Many machines are individually of relatively low value – imagine for example a temperature sensor. Chipset costs need to be in the region of $1-$2 and annual service charges less than $10 to make it worth embedding wireless technology in such devices.
- Excellent coverage. To make applications such as smart metering viable there needs to be coverage near 100% of all meters. With many meters deep within the home or even in basements this implies vastly better coverage than achieved with today’s cellular networks.
- Ultra low-power operations. Many machines are not connected to the mains and so have to operate on batteries. Having to change the battery is at best an annoyance and at worst a significant expense. Battery life of ten years or more is essential.
- Secure and guaranteed message delivery. While machines rarely need ultra-rapid transmission, they do need to be certain that messages have been received and that security of the system has not been compromised in any way.
There is no current wireless system that comes close to meeting all of these requirements. Cellular technologies do provide sufficiently good coverage for some applications but the hardware costs can be $20 or more depending on the generation of cellular used and the subscription costs are often closer to $10 per month than $10 per year. Battery life cannot be extended much beyond a month. Cellular networks are often ill-suited to the short message sizes in machine communications resulting in massive overheads associated with signalling in order to move terminals from passive to active states, report on status and more. The minimum effective message size for a GPRS-connected device is around 400 bytes once all the various signalling messages are taken into account, imposing a hundred-fold overhead on some messages. So while cellular can capture a small percentage of the market which can tolerate the high costs and where devices have external power, it will not be able to meet the requirements of the 50 billion device market. Indeed, if it could, it would have done so already and there would be no further debate about the need for new standards.
There are many short-range technologies that come closer to the price points. These include Wi-Fi, Bluetooth, Zigbee and others. However, being short range these cannot provide the 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 there may be good reasons why a wide-area solution is preferred. For example, an electricity supply company is unlikely to accept that their meter is only connected via, eg Zigbee, into a home network, which in turn connects to the home broadband. Were the home owner to turn this network off, fail to renew their broadband subscription or even just change the password on their home router, then connectivity could be lost. Restoring it might require a visit from a technician with associated cost. Maintaining security across such a network might also be very difficult.
Finally, it is critical that the technology is an open global standard, rather than a proprietary technology. With a wide range of applications there will need to be a vibrant eco-system delivering chips, terminals, base stations, applications and more.
William Webb is an independent consultant, is CEO of the Weightless SIG, is Mobile Communications Series Editor for Artech House Books, and is currently service as President of the Institution of Engineering and Technology (IET).
This report is an excerpt from Webb’s technical paper “IoT in Unlicensed Spectrum,” which is available exclusively for members of the International M2M Council. To read the full report, and to learn more about the benefits of IMC membership, click here.