Why another standard?
December 1, 2011It has been said in jest that “the nice thing about standards is that there are so many to choose from”. Of course, the purpose of a standard is that all those who adopt it do not need to make any further technological choice although they are free to select suppliers and so on. Equally, there are many examples of areas where multiple standards have led to confusion and actually been detrimental. So embarking on a new standard should not be undertaken lightly.
However, in the case of wide-area machine communications, there are no standards to choose from. Technologies like Bluetooth and Zigbee are for local communications, not over many km. Technologies like cellular are for wide-range but for people, not machines. While they can be adapted to machine use they are expensive, inefficient and unable to meet requirements such as decade-long battery life. Someone wanting to implement machine communications for, eg automotive engine management, at present does not have any standard to choose from. But standards are critical when multiple different applications need to share the same access networks and roaming globally may be required. Indeed, history has shown that wireless communications systems do not succeed unless they are standards and further that in most cases there is only room for one, or at most two global standards – examples include Bluetooth, WiFi, cellular, digital TV standards and more.
The aim of Weightless is to meet this need. Of course, others have sought to do so in the past but not been able to make progress due to a lack of radio spectrum that is affordable, globally harmonised, plentiful and in frequency bands with long-range propagation capabilities. What has changed this is the availability of “white space” spectrum in the TV bands which meets all of these requirements. But white space spectrum comes with its challenges including potential interference, both from the licensed users such as TV transmitters and other unlicensed users, a need to work with geolocation databases and more. These require quite specific characteristics that are not available in any existing standard – existing standards tend to be either short range and operate in unlicensed spectrum or long range and operate in licensed spectrum. So using white space enables machine communications but provides additional reasons why a new standard is needed.
Some of the key characteristics needed from a machine standard include optimisation for short messages (often less than 50 bytes), ability to handle up to 1 million terminals per cell, support for ten-year battery life, excellent authentication and encryption, global roaming, deep indoor penetration, tightly constrained radio emissions to avoid interfering with others and the ability to work in a environment where interference is uncertain.
The process of developing standards is not always a smooth one. Conflicting company priorities and the desire to secure essential IPR can delay and sometimes even derail a standards process. That is why Weightless is developing its own standards body – the Weightless Special Interest Group (SIG) and why it is insisting on royalty free licensing for terminal devices.
So happily, in this case, the nice thing about a machine communications standard is that there may only will be one to choose from.
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William Webb says: Bob,
You raise a very good point. Ofcom took a look at this in general a few years ago and concluded that there were a few high level things that could be done, but much of the coordination needs to be at a technology specific level. At a high level it thought technologies with similar power levels, ranges and duty cycles should be grouped together. It also said technologies should be “polite” for example by only transmitting when they needed to, using frequency hopping and implementing power control. But it concluded that in practice the best solution was for each new entrant into an unlicensed band to demonstrate how it could interwork with technologies already there. In the white space it is not yet clear which technologies will emerge (and they may not necessarily be the IEEE standards) so it is hard to tell whether they will coexist. It’s an area to keep a close eye on but not one where it is clear yet that standards bodies could add value……
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William, with no many wireless standards, particularly in the license exempt bands, and such poor co-existence performance between them, can anything be done to increase cooperation among standards-creating bodies?
Is anyone (e.g. IEEE) trying to create a workgroup on inter-standard compatibility improvement?