Tag Archives: 220MHz

IEEE 802.15 Positive Train Control Study Group

Many of you may be familiar with the IEEE 802 organization, if in no other way by its standards that have become the mainstay of wireless communications, like IEEE 802.11 (Wi-Fi), 802.16 (WiMAX), 802.15.4 (used by ZigBee, WirelessHART, ISA 100, 6LoWPAN, and others).

Standards development is a challenging matter, since it only comes by bringing together competitors and opposing entities into the same room and working together to create standardized approaches to a variety of problems.

The group that I helped to create, IEEE 802.15 Positive Train Control (PTC) Study Group, is focused on the vital wireless link between the train or locomotive and the infrastructure along the track ahead. While the current concentration is mostly to ensure that a train does not “exceed its limits authority” or exceed its speed restrictions, the future could see the need for a train to talk to bridges, overpasses, or other infrastructure that could impact the safety of a fast-moving train.

Now that we are in Study Group phase, this means that it’s time for us to concentrate on writing our Project Authorization Request (PAR) and our Five Criteria (5C) documents. To make that effort possible, the group will have a Call for Applications, which will allow interested parties to begin to submit technical proposals for how a future wireless standard will be applied in the real world. Fortunately, PTC is a fairly well defined application, but even there, there are nuances that may prove very important to the final standard. As well, this standard must be something that can grow and remain flexible for future applications which we may not even have considered yet.

While what we’re working on is a new standard, in IEEE parlance, the work could result in an amendment to an existing standard (like 802.15.4) or a new number (802.15.10?). That’s why the call for applications is so important – it helps establish the scope of the task.

Some important considerations might include the use of licensed bands, support for narrow-band, possibly non-contiguous radio channels, fairly low data rates, very high speed mobility, and a lot of non-line-of-sight (NLOS) propagation paths. As a train moves along, it may pass from one geographic region to another, and the operating channels may be required to change as the train moves. And it always needs to be kept in mind that this may ultimately be for vital (life and safety) communications, so reliability, robustness and security are important matters as well.

I’ve been working on systems in many ways similar to this for most of my professional career, from deep-space missions (where oops! could mean the end of a multi-billion US$ mission), to very high volume consumer and industrial silicon chip-level wireless systems, and for the past 10 years working to drive standardization of approaches used in the industry to reduce cost, increase the potential for interoperability, and generally to improve reliability and robustness.

If this is your cup of tea, I strongly encourage you to participate in our Study Group. You can get plenty of details here.