Downloaded from SAE International by Jeffr Blake, Friday, January 14, 2022
`
`912758
`
`Automobile Navigation System Using
`Individual Communication Beacon
`Hiroyuki Kanemitsu, Takaharu Saito, Junkoh Shima, and Yoshibumi Tanaka
`Toyota Motor Corp.
`
`ABSTRACT
`
`A communication system t hat uses roadside
`beacons to broadcast road and traffic information
`and private messages to vehicles has been
`developed. The system, called Road/Automobile
`Communication System (RAGS), was the result of a
`joint research project involving the Public Works
`Research Institute and 25 private-sector
`corporations. This paper contains an outline of
`RAGS and of an onboard system developed by TOYOTA
`and presents the results of field tests conducted
`in the Tokyo area. The results not only verify the
`capability of the RAGS system and the effectiveness
`of the in-vehicle . equipment but also indicate the
`potential of such a beacon based network to improve
`traffic jam and driving safety whilst providing
`enhanced communication facilities without increasing
`radio-wave congestion.
`
`INTRODUCTION
`
`Onboard navigation systems have become popular
`in recent years. For the most part, these navigation
`systems are digital dead reckoning systems that
`display map information from CD-ROM on CRT
`monitors. If the functions of navigation systems are
`to be improved, however, they must be capable of
`receiving and acting on real-time road information
`to guide the vehicles to the destination point. For
`example, these navigation systems would have to be
`capable of handling such chang~able information as
`traffic jam reports. Several countries are
`developing navigation systems targeting these goals.
`In Japan, three systems are being developed: the
`Road/Automobile Communication System (RACS), the
`Advanced Mobile Traffic Information & Communication
`System (AMTICS), and the Vehicle Information &
`Communication System (VICS), which is an
`amalgamation of the first two systems.
`TOYOTA has developed a prototype navigation
`system that uses two-wa y RAGS beacons. The system
`supplies traffic information to the driver, manages
`communications between the vehicle and the RAGS
`:enter, and enables the driver to forward
`
`information on road and weather conditions for relay
`to the appropriate authorities and other system
`users .
`
`ROAD/AUTOMOBILE COMMUNICATION SYSTEM
`
`Fig.1 outlines the RACS system, which basically
`consists of the RAGS center, roadside beacons and
`the in-vehicle communication and navigation
`devices. The onboard devices communicate by radio
`with the beacons, which are l inked to the center by
`a cable network. The principal RACS functions are
`as follows: -
`1. Navigation - When dead reckoning is used to
`calculate vehicle position, errors are inevitable.
`With RACS, when the vehicle passes a beacon, the
`onboard navigation device receives a location
`signal, which is used to correct the accumulated
`error in dead reckoning.
`
`CRT
`\_....:::::,~c...::._.,,....:::::__J display
`
`~ LB:location beacon
`.
`
`IB:location &
`information beacon
`L~B I~B ICB~
`ICB: location
`/
`/
`/
`/
`/
`/
`information &
`individual
`communication
`
`r
`
`-
`
`r
`I(]
`1_,,:,11•
`:
`"":::
`
`wTiillD:,::::
`
`beacon
`
`RACS
`Road
`author ity center
`
`Subscriber
`
`Fig.l Road/Automobile Communication System
`
`Exhibit 1023
`IPR2022-0427
`Page 1 of 5
`
`

`

`Table 1 Beacon specifications
`inf orma tion is
`2. Road & traffic information -
`. d d
`ff Qownloaded.fro!ll SAE lnternatipnal by Jetfr Blake, Friday, January 14, 2022
`r---'---'------------r------------
`provi e
`on present tra
`ic conditions, roaa works
`Microstrip antenna
`and road/lane restrictions. The onboard navigation
`Antenna
`2.538GHz
`device selects the information pertinent to the
`Transmission frequency
`2.598GHz
`input destination and displa ys it on the CRT.
`Reception frequency(ICB)
`lOmW
`Additional information relating to parking lot
`Transmission power
`BPSK
`location and vacancy conditions is also provided.
`Modulation method
`512kbps
`3. Private communication - Videotex and/or fax
`Transmission speed
`messages can be relayed between the vehicle and a
`subcriber. Digitalized voice messages can also be
`handled. In addition, provision has been made for
`Automatic Vehicle Monitoring (AVM) for fleet
`operators.
`
`---.---------tmodulation
`
`180 degree
`phase reversal
`
`,-·M·,·-,,
`'•'\'
`
`I
`I
`
`,
`
`negative
`phase
`
`I 11
`I 1'
`I
`\
`I
`I
`
`-'
`
`'-
`
`I
`/
`•
`
`._
`
`;
`
`'
`
`positive
`phase
`
`signal
`strength
`
`SYSTEM CONFIGURATION
`
`To provide these services, three kinds of
`beacons are required. A location beacon (LB)
`transmits its own location, the configuration of the
`next intersection and the destination of the roads
`emanating therefrom. An information beacon (IB)
`transmits road & traffic information as well as
`location data. It is connected to the RACS center by
`cable. An individual communication beacon (ICB) not
`only functions as an LB and IB but also permits
`two-way private communication. Another important
`feature of the ICB is that it can receive
`information from the vehicle regarding road &
`traffic conditions, making it a useful tool for road
`managemant.
`Beacon specifications are shown in Table 1.
`Data are transmitted on the microwave band. The
`communication zone is about 70m long and 15m wide.
`Each beacon is equipped with two antennas, one of
`which broadcasts in synchronized phase AM and the
`other in counterphase AM at a frequency of lkHz. As
`a vehicle approaches the beacon, the signal it
`receives is strong ; but the instant that it comes
`abreast of the beacon, the signal strength drops
`off, only to increase again in reversed phase as
`the vehicle moves away. Thus the onboard navigation
`device can precisely mark the beacon's position .
`Moreover, the phase reversal(+/- or-/+) enables
`the device to determine its heading relative to the
`beacon (see Fig.2).
`Communication beacons make use of Time Division
`Multiple Access (TDMA). The Abstract Syntax
`Notation 1 (ASNl:CCITT X.409) format is used to
`transmit and receive private messages. Fig.3 shows
`the communication protocol.
`
`~ data modulation
`: ~ (2.538GHz)
`
`/
`
`AM (lkHz)
`
`vehicle heading
`Fig.2 Block diagram of beacon
`
`The first set of information the vehicle
`receives is the beacon t ype (i.e ICB) and location
`data. The onboard private communication device,
`then rand om ly selects two of fort y time slots and
`transmits the vehicle's ID, such dual transmission
`reducing the possibily of non-reception by the
`beacon to almost nil. The beacon next transmits
`road and traffic inf ormation, after which it opens
`200 time slots for private communications. Each time
`slot has a capacity of 1,152 bits. The maximum
`number of time slots any one vehicle can utilize is
`200, but generally speaking the beacon should be
`capable of simultane ous ly communicating with 20
`vehicles. Finally the beacon and the private
`communication device acknowledge reception.
`
`Beacon side
`i
`
`t
`V ehicle
`
`side
`
`14,592 bits
`,~
`
`Beacon type &
`location data
`
`One frame Total 388,096 bits
`
`758 msec
`
`63,040 bits
`
`259,112 bits
`
`3,888 bits
`
`25,016 bits
`1'
`Vehicle ID &
`private
`communication
`request
`
`259,112 bits
`
`I
`
`6,720 bits I
`
`Road & traffic
`information
`
`Downward ACK
`
`Private Communication
`
`Upward ACK
`
`Fig.3 Communication protocol
`
`242
`
`D mode transfer period
`
`Exhibit 1023
`IPR2022-0427
`Page 2 of 5
`
`

`

`TOYOTA ONBOARD EQUIPMENT
`
`Fig.4 is a block diagram of the prototype
`onboard equipment. The information processing unit
`( IPU) has a 16bit capacity and functions both as a
`dead reckoning navigator and as a controller for the
`communication unit and other devices. For dead
`reckoning, the IPU receives signals from a
`gyroscope, wheel sensors, a speed sensor and a
`geomagnetic sensor. The monitor is a 6-inch CRT with
`touch sensitive switches (TSW) that the operator
`uses to control the system. In addition, there are
`two voice-synthesizer units - one for traffic
`information (TIVS) an~ one for priv a te
`communications (PCVS) - and a word processer for
`transmitting text messages.
`SYSTEM FUNCTIONS - The position of the vehicle
`as calculated by dead reckoning is superimposed on
`the map displayed on the CRT. The map display
`automatically shifts when the indicated position
`nears an edge of the CRT screen. As stated above,
`any error is corrected when the vehicle passes a
`beacon. At the same time, pertinent traffic
`information is added to the map display, and the
`driver is informed by a voice-synthesized message
`that information has been received. By pushing the
`appropriate key, the driver can listen to the TIVS
`identify congested roads. He can also change the
`map scale to pinpoint traffic jams visually.
`
`Downloaded from SAE International by Jeffr Blake, Friday, Jan%~~ \14~~02'f private message be received• the driver
`is informed both by the PCVS and by words which are
`superimposed on the CRT display. Pressing the
`appropriate TSW causes the message to be displayed
`and to be read by the PCVS. Simple, fixed
`replies/messages can be rel ayed via the RACS center
`by inputting the subscriber number and touching the
`relevant TSW. In the present prototype system,
`eighteen fixed messages have been provided, e.g.
`YES, NO, OK, ARRIVAL DELAYED. Other messages must
`first be written on the word processor and
`translated into ASNl format by the IPU. Eight fixed
`messages regarding road/weather conditions have
`also been pre-set for transmission to the RACS
`center. Exanples are : accident, ic y -surface,
`broken-down vehicle.
`MAP DISPLAY - The map data-base is contained in
`a ROM unit in the IP U. For the ongoing test
`purposes, the data cover an area of about 350 square
`kilometers, including Tokyo, Yokohama, and
`Kawasaki, and four kinds of map scales are
`available. However, for future use, provision has
`been made for a CD-ROM data-base to cover the whole
`of Japan with a greater selection of map scales.
`DEAD RECK ONI NG SENSORS - The basic sensors
`employed in dead reckoning are the distance sensor,
`which counts the re vo lutions of the drive-shaft,
`and the geomagnetic sensor. However as the latter is
`subject to interference from large ferrous masses,
`a vibration-t ype gyroscope and the wheel rotation
`sensor of the Anti-skid Brake System (ABS) are used
`to calculate changes in vehicle direction so that
`compensation is made for any error in the magnetic
`reading.
`COMMUNICATION UNIT AND ANTENNA - The
`communication unit consists of a 16 bit
`microprocessor and a transceiver. A micro strip
`antenna is used. Transceiver and antenna
`specifications are given in Table 2.
`
`Information
`
`CRT & TSW
`
`processing
`
`unit
`
`Voice
`synthesizer
`units
`
`Gyroscope
`
`Wheel sensors
`
`Speed sensors
`
`Geomagnetic
`sensor
`
`Communication
`unit
`
`l wo rd processor
`
`Fig.4 Onboard equipment
`
`Table.2 Transceiver and antenna specifications
`
`Transmiss ion frequency
`Reception frequenc y
`Transmission power
`Modulation method
`Transmission speed
`Reception level range
`Antenna gain
`
`2.598GHz
`2.538GHz
`lOmW
`BPSK
`512kbps
`-75 ~ -35dBm
`4dBi
`
`Fig.5 Proto-system
`
`If parking information is received, the location
`of parking lots can be shown on the map display and
`details of each lot, e.g. the number of current
`vacancies, parking charge, can be displa ye d and
`announced with s ynthesized voice.
`
`Fig.7 Micro strip antenna
`
`243
`
`Exhibit 1023
`IPR2022-0427
`Page 3 of 5
`
`

`

`FIELD TEST RESULTS
`Fig.8 outlines the method used to detect the
`lkHz AM phase rever sa 1 so Dggnl~~ e'fif£'\:-1tswg1ewitifB~8~ ~ffr Blake, Friday, January 14, 2022
`position. The incoming beacon signal is input to the
`Field tests have been conducted in the greater
`BPSK demodulator and the AM demodulator. The BPSK
`Tokyo area, principally on the Metropolitan
`demodulator unit outputs the demodulated data and a
`Expressway, using one LB, one IB, nine ICBs.
`recovered clock to the microprocessor. The
`DETECTION OF BEACONS - Fig.9 shows an example
`recovered clock is also input to a divider. The
`of results on detection of beacons. Because of the
`microprocessor detects the frame lead point and
`phase verification unit, the position of the beacon
`outputs a signal to the divider, which then converts
`is detected by the onboard navigation device with
`the recovered clock into a lkHz signal that is
`very reasonable accuracy .
`transmitted to a phase detector. The phase detector
`In all cases, the error in marking the
`determines the phase of the lkHz AM signal received
`beacon's position was within six meters. The delay
`from AM demodulator in accordance with the lkHz
`shown in the figure 9 was due the signal processing
`signal from the divider. Theoretically, the point
`time required by the circuit . If a delay coefficient
`is added to the computationn process in order to
`when the AM signal reverses phase can therefore be
`readily detected by the microprocessor. In
`compensate for the processing time, greater
`practice, however, external interference generates
`precision can be expected .
`fading in the AM signal and it is difficult to
`COMMUNICATIONS - The field tests confirmed
`precisely determine when the phase reversal occurs.
`viable operation of all one-way and two-way
`For this reason, a phase verification unit is
`communications. Since traffic information was
`incorporated in the circuit. This receive a speed
`updated at five minute intervals, the driver was
`pulse (about 60cm intervals) and examines the phase
`constantly aware of changes in road and traffic
`as indicated by the phase detector at each pulse
`conditions. The concensus of the testers was that
`input and judges the phase to be unchanged until a
`the information system was very beneficial as it
`plus is followed by four consecutive minuses or
`allowed them to alter their route to a v oid
`vice-versa. This "cl ean" signal is transmitted to
`congestion and gave forewarning of possible hazards.
`the microprocessor, which detects the phase reversal
`In particular it was felt that the voice synthesis
`and marks the beacon's position.
`made it easier to assimilate the information. The
`VOICE STNTHESIZERS - As previously mentioned,
`reception and transmission of private messages was
`two voice synthesizers are employed. The PCVS uses
`achieved most satisfactorily. Because all
`conventional speech synthesis, whereby syllables are
`communication are effected on the same frequency,
`individually synthesized and combined to form words
`the system may be considered to have considerable
`and ultimately sentences. Although enabling any
`potential for easing radio-wave congestion.
`text to be aurally reproduced, this system cannot
`create natural intonation and stress. To resolve
`these problems the TIVS stores Adaptive Delta Pulse
`Code Modulation (ADPCM) recordings of an actual
`human's reading of all the place names in the test
`area and of words and phrases such as "traffic is
`jammed","from","to" and "in the region of". Traffic
`information is received in terms of link numbers.
`The IPU analyzes the information and determines how
`many connected links are affected. It then compares
`the link numbers to a list of names of places and
`edits the information into a comprehensible format.
`Upon receipt of the encoded format, the TIVS
`retrieves the relevant voice patterns, thereby
`verbalizing the information as intelligible
`sentences.
`
`Fig.1O Display of congestion
`
`Intermediate frequency
`
`Communication
`microprosessor
`
`Data
`BPSK Demodulator 1----------------,,--------------------------;,t(data processing)
`Recovered clock
`
`Divider 1<:--------------------i(frame lead point
`Frame lead point
`detection)
`
`AM Demodulator
`
`1-------------,~ Phase detecter
`
`Phase verification unit
`
`Fig.8 AM Phase reversal detection method
`
`(phase reversal
`detection)
`
`Speed pulse
`
`Exhibit 1023
`IPR2022-0427
`Page 4 of 5
`
`

`

`Downloaded from SAE International by J.i~4'llall.!) FIIIP.i'/ ?f~J.l;!Fy 14, 2022
`
`l
`
`AM phase signal
`
`+
`
`L_ detection point
`
`Carrier
`reception level
`(2.538GHz)
`
`[ dBm]
`- 30
`
`-4 0
`
`- 50
`
`-60
`
`- 70
`
`- 8 0
`
`- 90
`
`~-1~~
`
`-too
`
`-80
`
`-60
`
`-4-0
`
`-20
`
`+60
`+40
`+20
`vehicle heading
`
`+80
`
`+100
`Distance
`
`!ml
`
`Fig.9 An example of the results on detection of beacons
`
`. REFERENCES
`
`[l] T.Saito et al .
`"Automobile Navigation System Using Beacon
`Informati on" The Vehicle Navigation & Informa tion
`Systems Conference (VNIS ' 89),Toront,Canada,1989 .
`
`(2) R.Fukui et al .
`"Individual Communication Function of RACS" The
`Vehicle Navigation & Information Systems Conference
`(VNIS'89),Toront,Canada , 1989.
`
`(3] Y.Shoji et al.
`"Toyota Elect ro Multivision" SAE880220,1988,pp.33 -
`88 .
`
`(4) S.Takaba et al .
`"Experimental Study on Road/Automobile
`Communication System in Japan " The 18th
`International Symposium on Automobile Technology &
`Automation (ISATA),198 8
`
`(5) R. Okamoto et a l .
`"An Overview of AMTICS" International Congress on
`Transpor tation electronics Proceedings,1988 ,pp.219-
`228.
`
`Fig.11 Display of received message
`
`CONCLUSION
`
`Field testing of a prototype nav
`igation/communication system has confirmed that it
`is beneficial both to the vehicle occupants and to
`road authorities . The RACS beacons utilized this
`system are expected to form part of a future
`Japanese network with enhanced infrastructure (VICS)
`. Further study relating to onboard equipment will
`be centered on improving the human - machi n e
`so as to facilitate the assimilation of
`interface
`increased information whilst not distracting the
`driver's attention from the road, and on the
`development of a navigation s ystem that revises the
`calculated optimum route in response to real-time
`information.
`
`ACKNOWLEDGMENT
`
`The RACS system wa s developed in conjunction
`with the Public Works Research Insutitute. The
`authors wish to express their gratitude to all those
`involved in the RACS proje c t and to those who
`cooperated i n the development of the onboard
`s ys t em .
`
`Exhibit 1023
`IPR2022-0427
`Page 5 of 5
`
`