by MATT VAN DAM, Laird Telematics & M2M Business Unit
Dedicated short-range communication techniques could usher in connected cars and safer driving.
Cars are getting more “intelligent” technology every year. Soon, that technology will let vehicles communicate interactively and share critical information. One result: fewer fender-benders. When the traffic in front of you slows dramatically, the vehicles ahead will signal to yours and alert you to the dramatic change in speed.
But this is only the beginning. Your vehicle may soon alert you to approaching fire trucks, traffic congestion or even potholes. Through smartphones, IoT-connected vehicles may communicate maintenance issues like tire pressure, fuel level or the need for new antifreeze, before these become serious problems.
Vehicles in the IoT won’t just connect to other vehicles. Traffic lights, cross walks and even the road itself could provide real-time information to make your trip safer and more efficient. This kind of connectivity also enables Internet browsing; passengers can start shopping before they hit the store or entertain themselves during a longer ride.
Automotive manufacturers and technology companies are now testing this type of connectivity. In fact, the noted industry analyst firm Gartner is predicting more than a quarter-billion “connected cars”—about one in five vehicles worldwide—will be on the road by 2020. And the cellular phone company Verizon shows an 83% growth year-over-year for the IoT market in transportation and distribution.
A critical election cycle
In about 18 months, the U.S. will have a new president. He or she will have an opportunity to help convert the information superhighway into a real American connected superhighway, where cars, trucks, pavement, infrastructure and related traffic systems will talk with each other to enhance auto safety and efficiency.
That’s because the next president will likely appoint a new chair and five commissioners of the Federal Communications Commission when their five-year terms expire in 2017 and 2018. Ditto for the U.S. Secretary of Transportation, a presidential appointee and member of the president’s cabinet, who oversees the Federal Highway Administration and the National Highway Traffic Safety Administration.
Together with the president and Congress, they’ll play a crucial role in shaping the future of America’s “smart” highway system. One challenge they’ll face is the fact that network-connected cars and highways will operate in complex radio frequency (RF) environments. Robust end-to-end infrastructure that enables immediate processing of life-critical, actionable data and greater data security will be a necessity.
This infrastructure will also require sophisticated antenna technology, high-performance radios, robust software, bandwidth and excellent coverage, ensuring vehicles stay connected with no blips or outages.
One network technology that can provide this kind of performance and coverage is called dedicated short range communication (DSRC). DSRC is based on the IEEE 802.11 standards used for WiFi, but it’s specifically focused on meeting the requirements for highway safety. (Its physical layer is defined by the IEEE standard 802.11p, an extension to 802.11 wireless LAN medium access layer [MAC] and physical layer [PHY] specification.) It’s a good candidate for the highway environment because it enables direct communication with other systems on the road—vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), and vehicle-to-everything (V2X)—thus requiring no cellular networks.
It is useful to review some of the technical aspects of these communication systems. DSRC uses 75 MHz of spectrum in the 5.9-GHz band that the FCC allocated for intelligent transportation systems. DSRC messages and messaging schemes are defined in the SAE J2735 standard. This SAE Standard specifies a message set and its data frames and data elements. The most fundamental message is the basic safety message (BSM). All vehicles send it periodically. It contains parameters defining a vehicle’s dynamic state, which are critical for safety applications, such as speed, heading and location.
DSRC operates over the Wireless Access in Vehicular Environments (WAVE) communication system. This standard is an amended version of the IEEE 802.11 standard (the common WiFi standard). The Federal Communications Commission (FCC) allocated a frequency band for DSRC from 5.85 to 5.925 GHz. DSRC divides this range into seven 10-MHz channels and a 5-MHz guard band. It uses orthogonal frequency-division multiplexing (OFDM) with four pilot and 48 data sub-carriers for each channel.
Of the seven channels, one is a control channel (CCH) used for safety applications. The other six channels, called service channels (SCHs), will be used for infotainment or commercial applications to get the cost of this technology down. Vehicles will synchronize the switching between the CCH and one or more of the SCHs in a way that prevents the loss of safety-related messages. A synchronization interval (SI) contains a CCH interval (CCI), followed by a SCH interval.
V2V is a communication scheme designed to let automobiles talk to each other. The systems also use the 5.9-GHz band. V2V is also known as VANET (Vehicular ad hoc network) and is currently in active development by major automakers. It is a variation of MANET (Mobile ad hoc network), a continuously self-configuring, infrastructure-less network of mobile devices where the nodes are vehicular.
In V2V, vehicles exchange information about location, speed, acceleration and braking. Because V2V allows this data exchange ten times per second, vehicles will be able to calculate a hazard risk within about 300 m and alert the driver or even execute collision-avoidance actions. Drivers will be able to see, hear and even feel the hazard signals through vibration of the seat.
DSRC also includes complex circuitry and software enabling it to create a unique identity for each vehicle to protect the operator’s privacy and the system’s data security. In addition, DSRC schemes will build in security measures as defined by a family of standards called IEEE 1609. They also provide for a resource manager that manages communication between remote applications and vehicles and communications through multiple channels. This standard also allows for both vehicular onboard units (OBU) and roadside units (RSU). RSUs act like wireless LAN access points and can provide communications with infrastructure. Finally, a third type of communicating node called a Public Safety OBU (PSOBU) is a vehicle able to provide services normally coming from an RSU. PSOBUs are mainly police cars, fire trucks and ambulances in emergency situations.
In outlying or rural areas, DSRC-equipped vehicles also would act as their own hotspots, relaying signals to each other, so there would be no dead-zones as long as vehicles are on the road.
Unlike WiFi, DSRC is designed to work with moving vehicles and to adjust for environmental challenges related to RF signal reflection, temperature variations, and high vibration. The technology is currently being tested and developed with the U.S. Dept. of Transportation’s Test Bed Program on roads in Michigan and other states.
With the resources of the IoT, the environment around the road can also play a role in managing the safety of motorists. DSRC antennas and devices can provide real-time data, letting vehicles detect motorcycles, cyclists and even pedestrians blocked from the driver’s view. The same technology could let traffic command centers monitor and re-route traffic around potential dangers. Street lights could adjust their brightness automatically for optimal lighting on a cloudy afternoon or during a rain storm. And the process of merging into traffic from a blind turn becomes less of a guessing game when the connected parking garage alerts you to approaching traffic around the corner.
There are benefits besides safety. With the IoT in place, in-vehicle navigation data would be more accurate with near real-time updates. Connected vehicles could share fuel efficiency data so drivers could get more miles per gallon by selecting the right routes.
A connected highway could also keep in touch with local governments. Maintenance crews could be alerted to potholes or icy patches when a connected car detects them. And circling for a parking spot may eventually be a thing of the past. Parking lots could provide near real-time data about the number of open parking spaces and directions to their location.
A standardized and regulated IoT environment, however, will only come after a great deal of innovation and collaboration among the automotive and networking industries. It also will require the cooperation and commitment of the new FCC and USDOT appointees, and the support of the next U.S. President.
Laird Tech, The Connected Highway
Filed Under: Wireless • 5G and more, Analog IC Tips