Editor's notes:
1. SEO tags: GPS, Internet of Things, IoT, M2M, GLONASS, Galileo, QZSS, Beidou/Compass,
Wi-Fi, MEMS, cellular, CANbus, automotive, 4G, LTE, ,
2. Extension Media channels/sites: M2M, Transportation, Automotive, 4G/LTE, Mil/Aero,
CompactPCI/ATCA, Smartphone, Medical
3. Mandatory Pull Quote: " It might seem intuitive that the world has positioning abundantly well
served. The fact is it does not."
CONVERGENCE OF M2M AND POSITIONING
By: Georgia Frousiakis, Director of Engineering GNSS, Telit Wireless Solutions
Deck: GPS has got you covered, unless you're inside, underground, or out of satellite range.
Next-gen cognitive augmentation solutions overcome satellite-only line-of-sight limitations.
In a not so distant future, a conversation around the water cooler might go something like this:
“Do you remember when we used to say GPS as short for positioning?” GPS will, of course,
continue in the role of key ingredient, or certainly one of the top technology elements in
positioning solutions. Positioning is however quickly moving to become the result of a long
recipe of technology ingredients coming together in a cognitive architecture.
One of the key drivers of this accelerated shift is machine-to-machine communications (M2M).
Device makers were quick to realize that as they connected machines to each other, to servers,
and to the Internet-of-Things (IoT), the very next thing they required was the knowledge of
where these machines are located. This need was even more pronounced in mobile devices
such as cars, buses and construction equipment.
With the proliferation of connected devices, needing to know a position became an imperative.
It became instantly inacceptable that a position fix was contingent on line of sight to a large area
of sky. Devices and machines need to know where they are, and to communicate that position
whether they are underground, inside a building, under a bridge or in a container inside a ship.
The Quick Rise of Positioning
GPS was conceived during the “Space Race” between the Soviet Union and the United States,
primarily for use by Armed Forces to overcome limitations from its military-use-only
predecessor. GPS gave us all our first true experience with positioning when it went live in
1993. It has since served the military and civilian worlds for decades as a source of latitudelongitude coordinates used by devices ranging from tactical weapon targeting systems to
today’s smartphones.
However, over the last decade other satellite-based positioning system initiatives from
governments in other parts of the world have risen to add to GPS. Thus, Global Satellite
Navigation Systems (GNSS), a generic term created for satellite navigation systems that
provide autonomous geo-positioning with global coverage (see Table 1), was introduced.
Projects in Russia, China and Europe have managed to gain and sustain momentum. The
Russian GLONASS system, originally completed in 1996 was brought back to an operational
state in 2011 as the Russian economy recovered. China’s Beidou/Compass system became
operational in 2011 for local use and is slated for complete global coverage by 2020. The EU
network Galileo began sending test signals from its third satellite at the beginning of December
2012. India (GAGAN) and Japan (QZSS) have also announced satellite-based systems and are
currently in different stages of development and planning.
GPS
GLONASS
Galileo
Beidou/Compass
QZSS
USA
Global
1993
L1=1575.42MHz
24-32
Russia
Global
1996/2011
L1=1602MHz
~ 30
EU
Global
Future (ex. 2015)
E1=1575.42MHz
22-30
China
Global
Future (ex. 2018)
B1=1589.74MHz
30-35
Japan
Regional
Future (ex. 2020)
L1=1575.42MHz
4
System
Type
Date Deployed
Frequency
Number of Satellites
Table 1: Key Global Satellite Navigation Systems (GNSS) technologies.
Satellites Alone Fall Short of the Solution
With this large number of constellations, standards, and, foremost, features, it might seem
intuitive to assume that the world has positioning abundantly well served. The fact is it does
not. Not by relying solely on satellite-based location anyway. It is a fact that with every new
generation of satellite location receiver chipset, the number of supported constellations will
increase. It will eventually get to the point where all commercial satellite-positioning systems will
be supported by all chipsets.
There is however a fundamental weakness in satellite-based location systems. They all rely in
some shape and form on the ability to receive and resolve some very low-intensity radio
transmissions from these satellites. To mitigate some of this, the GPS hardware is being
upgraded with new Block 4 and 5 satellites flown into orbit to integrate the constellation and
boost transmission power. Still, there are circumstances such as obtaining fixes deep inside
buildings, tunnels, urban canyons, and underground where the solution requires augmentation.
Going Beyond Satellites
With the multi-trillion dollar consumer electronics industry, and others less rich but equally
influential like machine-to-machine (M2M) clamoring for solutions, solutions have been
forthcoming. Generically referred to as Assisted GPS, the process of enhancing a device’s
ability to obtain a position fix anywhere entails using a mosaic of different types and sources of
data. These include downloading ephemerides data (part of the GPS broadcast data) off a
server or from the satellites themselves while they are visible and storing them; triangulating
signals from cellular communication towers; using Wi-Fi hot-spots in range of the position
seeking device; “dead-reckoning” algorithms taking advantage of miniature high-resolution 3-
axis accelerometers, 3-axis gyro and micro solid state altimeters for both asset as well as
pedestrian tracking, and other exciting new developments in technology.
The answer is clearly not abandoning satellite-based positioning, but augmenting it to address
the specific set of circumstances when reception of signals from enough satellites is impossible.
Below we discuss some augmentation solutions available that are gaining momentum as
positioning takes its place in fundamental electronics.
Autonomous Assisted GPS
Autonomous assisted GPS is a scheme to mitigate the satellite-only weakness in positioning. It
captures GPS broadcast ephemerides (a kind of moving map of where satellites are likely to be
over time) when the device is under open sky and stores this information in its internal
database. The receiver works to maintain this information as fresh as possible, so that when the
time comes, it can use it to predict future ephemerides (See Figure 1). With the internal
database continuously updated with new ephemerides, the predicted ephemerides are then
updated as well and the expiration time of the prediction—the time after when the prediction is
deemed too unreliable to be used—is also moved forward. Under the current technology, if the
ephemerides database is not updated, the predicted ephemerides can be used for up to about
five days in the future before they will expire.
Autonomous assisted GPS is a robust enhancement since it relies on the device “seeing” GPS
satellites for a few hours every five days or so. That turns out to be a reasonably acceptable
assumption to make for most M2M applications. But, the expiration time of the predicted
ephemerides does depend on the last time that the broadcast ephemerides were updated.
Figure 1: Position error probability according to age of ephemerides data (1-5 days)
Cellular Service Based Positioning
These are cloud-based positioning services that provide a cellular-connected M2M device
position based on observed cellular Cell-IDs. They are able to provide city-block accurate
positioning information only, but they can do it entirely independently of the ability to see, or
even have a satellite receiver. The information from this type of service can optionally provide
real-time GNSS assistance data to accelerate satellite-based fixes, including server-based
ephemeris prediction data valid for up to 31 days.
The way Cell-ID positioning works is by cross-referencing the current identification of the cell
towers that the device can “see”, with a global database of the world’s more than 40 million cellIDs. With that cross-reference, the service can interpolate the most likely position of the device
(see Figure 2). This type of service can provide a position for every use-case including
indoors/underground, outdoors, and boundary situations. For devices with satellite receiver
capability and a good view of the sky, it can provide an approximate position while the receiver
determines a more accurate fix.
Figure 2: Position fix interpolated by obtaining position and geometry of cellular cells in range of a device.
Wi-Fi Based Positioning
Similarly to the cellular-based, this service can provide a position based on observed Wi-Fi hotspots. These access-points can be looked up in databases containing currently nearly half a
billion hot-spot locations, and can produce a position fix autonomously or assist the satellite
receiver with an initial position fix.
Dead-reckoning
Dead reckoning (DR) takes inputs such as yaw and distance from several types of motionrelated sensors, and does the “math” to determine where you are now by taking your last
absolute fix and projecting where you moved. This last known position is typically obtained from
the satellite receiver. This is common practice in today’s M2M Telematics solutions where
motion information is readily available on the car’s CAN bus (see Table 2). In-vehicle dead-
reckoning systems have a good supply of sensor data such as individual wheel speed coming
from ABS breaking systems or speed data from the odometer plus compass data.
DR Configuration
Yaw Rate
Sensor
Distance Sensor
Other Sensors
Classic
MEMS Gyro
(1 or 3 axis)
CAN Gyro
Discrete Odometer
CAN DWP
(ABS)
CAN Odometer
Discrete Reverse
Signal
CAN Reverse
Signal
CAN Reverse
Signal
MEMS Gyro
(1 or 3 axis)
CAN Odometer
CAN Bus
Differential Wheel
Pulses (DWP)
Mixed
CAN Odometer
CAN Reverse
Signal
Table 2: DR-based continuous navigation during satellite obscuration by use of sensors
The Cognitive Positioning Future
At Telit we are currently working on helping this transition from GPS to positioning happen by
researching the neural-network-like architectures that bring all these sources of data together
into a cognitive system. The result is that when these new positioning solutions arrive, they will
promote the final transition from our industry’s humble GPS beginnings to a hybrid-positioning
module. In the future, this positioning module will be an electronic component which will
unequivocally and reliably deliver data accurate enough to let you know that you are standing at
the east elevator lobby on the 42nd floor at 30 Rockefeller Center. At Telit, we are working to
combine all of the components discussed in this article into a cognitive solution based upon
GPS, AGPS, DR, Wi-Fi, cellular ID, and more.
Georgia Frousiakis, Director of Engineering GNSS, Telit Wireless Solutions
Georgia Frousiakis received her BSEE from California State
University in Fullerton, California. She then worked in various
design, system, and engineering capacities before becoming
GPS worldwide customer applications manager at Rockwell in
Anaheim and Newport Beach, California. After Rockwell, she held
GPS applications and technical marketing management positions
at IBM and RF Micro Devices. She is recognized on the global
stage as a leader in the design and application of GPS
functionality. She is presently the Director of Engineering GNSS
at Telit Wireless Solutions in Foothill Ranch, California.