[introduction] to consumer and motorcade, wireless fixed position / distance feeling is measured and safe communication is to ensure burgeoning car system has the mainstay of outstanding and convenience sex, function, security and safe function. People assists functional demand to increase ceaselessly to drive automatically and enhancing a driver. However, the stone’s throw with familiar people measures a technology to exist in car application relative to positional feeling limitation, among them the most apparent have:

● Defer / the position replaces rate

● Fixed position precision, and

● Along with the security that adds communication function

The technology of a recent reuse, exceed broadband technology namely (UWB) , hopeful enhances stone’s throw to measure a function relative to positional feeling significantly, ensure the communication between car is safe, develop a lot of previous unworkable advanced car function.

What is UWB?

Exceed broadband technology (UWB) is a kind of wireless standard that is based on IEEE 802.15.4z, aim to provide exact location and safe communication. UWB is in defer of precision of dependability, fixed position, fixed position / newer rate and security aspect excel a lot of existing wireless standards, not only economy is substantial, and cabinet and compact. In addition, as a result of the property of agreement of UWB physics layer, UWB communication and positional feeling measure the effect that does not suffer multichannel diameter and interference, can realize feebleminded bad news at the same time (graph 1) .

Graph 1: UWB is seen without exception

What is the working principle of UWB?

UWB is used super- wide bandwidth and have extremely steep rise / the short pulse of decay time (second of about 2 accept) , use key of binary phase shift to accuse (BPSK) and / or arteries and veins modulation (BPM) has code to data. UWB uses two successive pulse radio (IR) signal will represent a sign, and IR signal can hold frame of a time (inside Tf) one piles up an interval (Tc) . The code when jumping is used at deciding signal the exact position inside frame of a certain specific time, reduce the chance that interference produces between UWB system as far as possible thereby (graph 2) .

Graph 2: Exceed a broadband to use extremely narrow short pulse alignment to transmit information.

Every time UWB communication brings time stand sth on end. Time jab allows to use the signal flight time between two radio device (ToF) , will calculate the distance between device of these two radio, nod namely bit righter (P2P) two-way range finding (TWR) .

This kind measures the method that two UWB are apart from between communication radio not only safe and distinctive, and the effect that does not get multichannel way, because the shortest way often is two radio between most stone’s throw.

Through expanding further this concept, distributing in order to include to be nodded in the additional anchor in whole environment, can realize real time navigation. Use the many synchronous anchor inside the space to nod, use arrival time is wrong at the same time (TDoA) or retrorse TDoA (RTDoA) , can decide label the exact position inside 3D space.

Hypothesis UWB label contains much root antenna. Below this kind of circumstance, through determining the distance of communication radio and direction, use arrive at phasic difference (PDoA) , can calculate the relative position of two equipment.

Locate the technology is summarized currently

Current, use technology of contemporary and wireless communication to undertake is apart from / the method that the position measures has 5 kinds: RFID, Wi-Fi, blue tooth, GPS and UWB. RFID, Wi-Fi and blue tooth use RSSI computation space. RSSI uses Yu Heng to the quantity blasts off and receive the opposite signal strength between radio, below the condition that knows specific channel news, can use at crude guess distance. Another kind of method is GPS, it measures user facilities (UE) and the ToF between many time synchronism satellites, can use at computation the 3D position of constellation of opposite Yu Weixing. The technology of IR UWB ToF that finally is Qorvo (graph 3) .

The main distinction between these methods and Qorvo IR UWB ToF depends on, UWB method uses the extremely tall bandwidth with very short time to carry frequency signal. ToF system uses tape to be in only narrow frequency paragraph upload the short pulse that be defeated. Wi-Fi, blue tooth and RFID also use ToF, but bandwidth suffers be restricted, compare with UWB photograph, they cannot be generated have rise quickly / the extremely short pulse of decay time (the edge is clear) (graph 4) . Of UWB exceed broadband bandwidth to state signal energy distributings in whole exceed broadband Duan Fan to surround inside, this is meant be in any giving below frequency, the agreement is opposite and character does not get disturbing influence. This kind of very fast rise / the effect that decay time and brief UWB pulse time reduced much classics to disturb as far as possible, can realize very exact time to measure, enhanced definition thereby.

Graph 3: All sorts of wireless fixed position and communication standard are comparative.

Graph 4: The distance between ToF of RSSI, Wi-Fi, blue tooth, tape and Qorvo IR UWB ToF / fixed position is measured quite.

Above is mixed with blue tooth, Wi-Fi namely RFID photograph is compared, UWB can be in the reason that the distance realizes centimeter of class precision to measure between two more remote equipment relatively. In addition, the highest handling capacity of UWB communication agreement is 27Mbps, prep above eliminates all and other agreement besides Wi-Fi. Extremely short pulse and fast distance / positional computation makes clear, UWB can use those who suit 3D to dog inferior millisecond speed undertakes real time is apart from / fixed position dogs, make an appointment with 100 times more quickly than GPS. In addition, UWB label and anchorage site cost are low, effect is tall, what can achieve agreement and hardware support is large-scale patulous.

Face the UWB of car application

The traditional and long-range entrance guard that do not have key (433MHz car adds close dog / remote control key) be not is the safest solution that prevents crasher to enter a car, this is no wonder. A few foregone flaw attack of these equipment can allow a visit sometimes, control a car even. Accordingly, car couplet net is allied (CCC) made brand-new standard, use UWB technology to found a kind more safe do not have solution of key entrance guard remotely.

In fact, the UWB standard of CCC uses the safety like credit card to protect a type. The car manufacturer of the United States, Japan and European Union has begun to use level of this one UWB, encourage Chinese car manufacturer to also use this level all the time at the same time. 2018 the 3rd quarter, CCC begins to use UWB (HRP-UWB) of high rate pulse, this technology can raise the each other between car and mobile manufacturer to operate a gender, dislodge equipment can use as remote control key.

First of car UWB are used exemple do not have key entrance guard namely / start without key (PEPS) , should use a NFC technology that used CCC to accord with PEP of entrance guard system to plan the 2nd stage, with low power comsumption of the UWB that reachs the 3rd level and blue tooth (BLE) technology.

UWB radar technology is very sensitive, can use at detecting the mankind breathes…

Another uses a stone’s throw radar that uses UWB, through detecting the personnel of car inside and outside and object satisfy brand-new safe requirement, if inbreak,car and passenger detect or enter mothball case easily. UWB radar technology is very sensitive, can use at detecting the mankind breathes, OK even and divisional adult and infant. This conduces to not only prevent child and infant bequeath to be inside the car, when still can be asleep in the driver or losing action ability, issue warning to driver protection system.

Graph 5: Burgeoning the car UWB that reachs future to may appear is used exemple.

Another of UWB is used exemple ensure electric car is automatic and wireless namely automatism safety, this function can drive UWB electric car wireless charge area, share an evidence automatically next and finish charge trade (graph 5) .

Car UWB hardware and software

Digital key (system of DK) car entrance guard is the first burgeoning car UWB application, it can join the mobile phone that supports UWB technology not only to the car that outfits UWB, implementation does not have function of key entrance guard remotely, still can provide higher security. Pass accredit server, DK technology offers the steam door that use illicit key realizes to ban a function for the mobile phone. Through mobile phone and automobile safety element (SE) is finished initiative close key exchange, need not undertake cloud join also can realize automatic car entrance guard (graph 6) .

We are an introductory PEP system with high-end car, can use deploy place to require UWB, BLE, NFC and equipment of electronic SE (eSE) (configure beforehand) mobile phone or remote control key, the visit outfitted the car of compatible hardware and SE likewise. In this give typical examples, every UWB in the car is sent and receive implement (TRx) (also call UWB anchor to nod) one covers limits group, should carry out BLE signal exchange to be able to realize safe visit only (graph 7) .

Graph 6: Give typical examples of hardware of car of PEPS high end

Graph 7: PEPS car hardware realizes give typical examples.

Want BLE system to carry out network discovery and UWB to wake up a function only, UWB range finding and safe test and verify can spark system of bus line of the CAN inside the car, so that start mechanism of the automatic and long-range entrance guard that do not have key. Dot of anchor of the many UWB inside the car can realize a mobile phone or the essence of remote control key decides detect, and can increase a few safe functions. The remote control key that provides ESE and NFC or mobile phone serve as reserve system, when the NFC label that approachs a car, also can enter this kind of car.

UWB and V2V

Through adding other UWB sensor, check UWB range finding and car at the same time car (photograph of V2V) communication link is united in wedlock, we can use V2V to pass UWB information, in order to establish UWB area network. Safe information can be shared between the car of travel so, assist full automatic or semi-automatic drive or navigation system undertakes safety is coordinated and avoid barrier, or move to the hand with other way drive the car issues warning (graph 8) .

Graph 8: Use UWB and the sensor confluence function that V2V corresponds.

Graph 9: Sensor of commonly used car is compared.

The accuracy of UWB, dependability and rapid newer rate make response can be made quickly between car. Below some circumstances, UWB can replace cost even taller, calculation is more complex photograph system resembling a head, detect with fraise with realizing car to coordinate (graph 9) .

Conclusion

The function of car sensor technology of current deploy is put in certain difference. Fortunately, newer recently wireless sensor technology can realize cost low, newer rate is high and very accurate compact model distance / fixed position feeling measures a solution, and correspond relative to higher data rate, can make up for this one difference thereby. UWB hopeful implementation corresponds to be measured to passenger safety feeling from V2V wait for a large number of potential application. Best technology has not appear, because be able to apply extensively as UWB technology, it is an organic whole with car and smartphone be in harmony, this technology will develop further in future.

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