NEW TECHNOLOGY (1) UWB

NEW TECHNOLOGY

(1) UWB — new lower cost all-purpose DSRC

Those heavy gantries on the ramps of 407 in Toronto with all those different antennas could be obsolete in a few years time. And all the current standards making exercises for Dedicated Short Range Communications (DSRC), the CEN, ASTM, Title 21 etc could turn out to be irrevelant.

Emerging from the closet of Cold War secrecy is a new radio technology that could take over from a lot of the current electronic tolling and other vehicle-to-roadside (VRC) gear. Navy SEALs already use it for secure communications. Attack helicopters are being fitted with it for flying low and fast at night. The US army uses it for finding buried non-metallic mines. Various unmanned or robotic devices depend on it for sending and communications. It goes by different names — Ultra-Wide Band (UWB), BAseband Radar(BAR) and Micropower Impulse Radar (MIR). We’ll call it all UWB. It’s a family of radio technologies of such extremely low power, wide sprectrum and short pulse that it is very difficult to detect except by equipment that “knows” almost exactly what it is looking for. To the extent it is detected it seems like background noise. That’s how it came to be used so much by the US military, and why firmns specializing in it were until now prevented by security rules from developing civilian applications. Its low probability of intercept and detection (LPI/D in Pentagonese) is helpful in DSRC because it reduces incidence of interference with reserved spectrum radio and therefore minimizes licensing difficulties. It can coexist with all kinds of licensed equipment because it is spread over such wide bandwith that within any single narrow band it is largely undetectable.

A partnership of Virginia Tech and Multispectral Solutions (MSSI) a Gaithersburg MD firm is building the first UWB equipment for electronic tolling and VRC applications, assisted by a grant from the Transp Research Board (TRB).

The pioneers of UWB says one of its beauties for VRC is that the same signal can be used equally for data transfers (communications) and for rangefinding, tracking and even vehicle profiling. This multi-purpose aspect of UWB promises to simplify the task of sensing and communicating simultaneously with a stream of cars traveling down a road. UBW can deploy a very wide area antenna so there will be a relatively long period during which a passing vehicle is in the field of communication and sensing.

The most advanced current electronic toll system in operation (nearly in operation) that uses both tracking and communications is on 407 in Toronto. Using regular narrowband radio technology this Hughes system needs separate passive tracking antennas from communications antennas, and the gear needs to be very precisely aimed to work properly, something that you can see in survey markings on the blacktop under the 407 gantries. Most electronic toll collection systems operate with a reader/antenna designed with a narrow beam of coverage so that only one vehicle at a time can be within it, eliminating confusion as to which vehicle is which. That’s fine so long as the messages to be sent back and forth are simple and short and vehicle speed not too high, so it is just long enough in that narrow beam to complete communications. But the faster the speed of the vehicle the shorter the time frame for narrow beam vehicle-to-roadside communications, so the less time there is for the messages to be sent and successfully received and responded to. On highway 407 which was designed entirely for full highway speed tolling the Hughes system has wider area communications coverage to give time for larger messages to be sent back and forth than most other e-toll systems. But the tracking of each vehicle within a multi-vehicle coverage area becomes an essential, and tricky, component of the system.

UWB is a form of radio signal which can can track, profile and communicate from the one antenna and the antenna needed is much simpler and cheaper than present narrowband equipment. Many different groups are working on exploiting UWB’s inherent advantages. For example Lawrence Livermore Laboratories CA have announced they can build an UWB radar on a chip for $10 bought in quantity. It is one of the favored technologies for collision warning and avoidance systems. The military uses are endless — tactical data links, talk channels, altimeters, targeting for smart weapons, battlefield intelligence gathering.

At Highway 407 all the narrowband equipment looks down onto the roadway from a heavy gantry that spans the ramp. Every time they have to clean the lens of a laser profiler or tune equipment two service vehicles have to go out, one to block traffic so that the bucket-truck in front can stop safely on the highspeed ramp next to the gantry and then back in to the service pad. The bucket truck is needed for the serviceman to get up onto the gantry. The UWB people say their equipment will work in the VRC mode at chest or head height and can be mounted on a small post or cabinet. They use “patch” antennas, inconspicuous flat squares with a wide angle of coverage because separate vehicles operate in separate timeslots and multipath (or signal bounce) problems are handled via a receiver gate keyed to direct reception. And a UWB transponder using orders of magnitude less electricity than regular narrowband will need a far smaller battery and be more compact, perhaps credit card like in construction.

UWB uses so little power because it has such a short pulse (nanoseconds) and the signal is unlike the characteristic sinosoidal curve shape of most radio signals, more naturalistic they say, certainly tailormade for digital communications as compared to the signals which are a derivative of analog radio. The nanosecond pulse length of UWB compares with microseconds in regular narrowband communications. This makes UWB a natural technology for time division multiple access (TDMA), the principle already adopted in ATMSv6 for truck weigh station bypass, border crossings and wherever longer data messages are needed than in simple tolling applications. In TDMA vehicle-to-roadside communications each vehicle is allocated its own separate time ‘slots’ within each second. The finer the time division, or the shorter the slots, the greater is the system’s multiple access capability, giving the wideband, theoretically, orders of magnitude advantages over narrowband TDMA.

Multispectral Solutions Inc (MSSI) is a small (about 12 people) communications hardware development company that has had most of its business with the military around the Washington DC area, developing tactical communications and sensing systems hardware with similar ranges to VRC — 100m to several kms. It is run by Robert Fontana formerly an electrical engineering prof at Carnegie Mellon Univ. Other companies active in UWB are Pulson Communications, a spinoff of Time Domain Systems Inc in Huntsville AL, and Aetherwire & Location of Monrovia CA which has announced a chipset for VRC. Pulson has demonstrated megabit/second data transmissions at kilometer range with just 100 milliwatt power. It has its major focus on supplying new generation mobile phone equipment based on UWB. Bob James in charge of business development at Virginia Tech’s Center for Transp Research in Blacksburg VA says he surveyed the field and felt MSSI’s approach was the most promising for VRC. The others use pulse trains and the widest bandwidth (>100% bandwidth to center frequency) whereas MSSI uses single pulse system and moderate bandwidth (30% BW to CF). They’ll demonstrate it for you at their offices in Perry Parkway right alongside I-270 and the main CSX rail line in Gaithersburg MD, an area of huge radio activity I know because the radar detector in my car always goes so crazy there I have to turn it off. From within the offices they can use their handheld military UWB radios operating in L-Band between 1.2 to 1.7 GHz to send a 10Kb data file at 57 Kb/s to a passing car 200’ away. A conventional radio receiver has to be placed within a couple of feet to pick up any signal at all, showing what minimal interference UWB will generate with narrowband. They’ve had government and industry folks out by the score to their Perrry Parkway place to discuss DSRC requirements and to see their first improvised demonstrations.

The Transportation Research Board is negotiating details of a development project with MSSI and Virginia Tech. They say a paper for TRB they will “develop new dedicated short range communication devices for a broad range of Intelligent Transportation System applications using emerging ultra-wideband communication technology.”

“UWB, by virtue of its extremely short pulses offers the capability for high bandwidth multiple access communications as well as high accuracy (less than a foot) positioning and location measurement. Using UWB carrier sense multiple access technology a single inexpensive roadside device can be used to communciate simultaneously with large numbers of vehicles traveling in multiple lanes. In addition position information can be acquired and communications data transferred through the use of devices mounted alongside the road. This eliminates the cost of construction and maintenance of overhead gantries...It is anticipated that this technology will greatly reduce the cost of in-vehicle (toll) tags, roadside electronic toll collection devices and installation. It can also become a standard system for common ITS applications such as in-vehicle signing, electronic clearance, electronic license plates, collision avoidance, automated highway systems, vehicle-to-behicle communications, parking payments and access control.” (Contacts Bob James Virginia Tech 540 231 7740 bjames@ctr.vt.edu, Rob Mulloy MSSI 301 590 3978 mssi@his.com)

Sounds as if this wide stuff might put Rick Schuman, Lee Armstrong, Larry Yermack , Sompol and the other shuttle-diplomatists of DSRC standards out of business? Heck, no! It opens up a whole new line of standards making. Soon we’ll have two sets of committees, DSRC/Narrow for the fogies and the new sexy DSRC/Wide for the futurists. (Rick Schuman ITSA 202 484 4543)