阅读说明：本技术 定位系统和方法 (Positioning system and method ) 是由 吉亚斯·阿尔-卡迪 乌尔里希·安德烈亚斯·米尔曼 迈克尔·朔贝尔 于 2020-09-28 设计创作，主要内容包括：根据本公开的第一方面,提供一种用于确定可移动对象的地理定位的定位系统,所述系统包括：多个锚点,其中每个锚点被配置成通过超宽带通信信道接收广播消息；处理单元,所述处理单元被配置成基于对应锚点处所述广播消息的到达时间之间的差、所述锚点的相对位置和所述可移动对象的预定朝向来确定所述地理定位。(According to a first aspect of the present disclosure, there is provided a positioning system for determining the geolocation of a movable object, the system comprising: a plurality of anchors, wherein each anchor is configured to receive broadcast messages over an ultra-wideband communication channel; a processing unit configured to determine the geographic position based on a difference between arrival times of the broadcast messages at corresponding anchors, relative positions of the anchors, and a predetermined orientation of the movable object.)

1. A positioning system for determining the geographic position of a movable object, the system comprising:

a plurality of anchors, wherein each anchor is configured to receive broadcast messages over an ultra-wideband communication channel;

a processing unit configured to determine the geographic position based on a difference between arrival times of the broadcast messages at corresponding anchors, relative positions of the anchors, and a predetermined orientation of the movable object.

2. The positioning system of claim 1, wherein the processing unit is configured to determine the difference by: one of the anchor points is selected as a reference anchor point, and a difference between the arrival time of the broadcast message at the reference anchor point and the arrival time of the broadcast message at the other anchor point is calculated.

3. The positioning system according to any of the preceding claims, wherein the arrival time is based on a timestamp indicating a time of reception of a predefined tag in the broadcast message.

4. The positioning system according to any of the preceding claims, wherein the processing unit is configured to receive data indicative of the predetermined orientation of the movable object from an inertial measurement unit.

5. The positioning system of any preceding claim, wherein the plurality of anchor points comprises three or more anchor points.

6. The positioning system according to any of the preceding claims, wherein each anchor point is configured to receive a further broadcast message over the ultra-wideband communication channel, and wherein the processing unit is configured to determine the orientation of the movable object based on the difference between the arrival times of the broadcast messages at the corresponding anchor point and the difference between the arrival times of the further broadcast messages at the corresponding anchor point.

7. A positioning system for determining the geographic position of a movable object, the system comprising:

a receiver configured to receive one or more broadcast messages and to determine an angle of arrival of the broadcast messages;

a processing unit configured to determine the geographic position using the angle of arrival of the broadcast message.

8. A navigation system, characterized in that it comprises a positioning system according to any of the preceding claims.

9. A positioning method for determining the geographic position of a movable object, the method comprising:

receiving, by a plurality of anchor points, a broadcast message over an ultra-wideband communication channel;

determining, by a processing unit, the geographic position based on a difference between arrival times of the broadcast messages at corresponding anchors, relative positions of the anchors, and a predetermined orientation of the movable object.

10. A computer program comprising executable instructions which, when executed by a positioning system, carry out the method according to claim 9.

Technical Field

The present disclosure relates to a positioning system for determining the geolocation of a movable object. Furthermore, the present disclosure relates to a positioning method for determining the geographical position of a movable object, and to a corresponding computer program.

Background

Positioning systems typically utilize satellite signals. For example, the Global Positioning System (GPS) is a satellite-based radio navigation system that provides geographic positioning and time information to a GPS receiver embedded in or attached to a moving object (e.g., a vehicle). Such systems may determine the geographic location of a mobile object. When embedded in a vehicle, the GPS receiver may, for example, enable a navigation system.

Disclosure of Invention

According to a first aspect of the present disclosure, there is provided a positioning system for determining the geolocation of a movable object, the system comprising: a plurality of anchors, wherein each anchor is configured to receive broadcast messages over an ultra-wideband communication channel; a processing unit configured to determine the geographic position based on a difference between arrival times of the broadcast messages at corresponding anchors, relative positions of the anchors, and a predetermined orientation of the movable object.

In one or more embodiments, the processing unit is configured to determine the difference by: one of the anchor points is selected as a reference anchor point, and a difference between the arrival time of the broadcast message at the reference anchor point and the arrival time of the broadcast message at the other anchor point is calculated.

In one or more embodiments, the arrival time is based on a timestamp indicating a time of receipt of a predefined tag in the broadcast message.

In one or more embodiments, the processing unit is configured to receive data indicative of the predetermined orientation of the movable object from an inertial measurement unit.

In one or more embodiments, the plurality of anchors includes three or more anchors.

In one or more embodiments, each anchor point is configured to receive a further broadcast message over the ultra-wideband communication channel, and the processing unit is configured to determine the orientation of the movable object based on the difference between the arrival times of the broadcast messages at the corresponding anchor point and the difference between the arrival times of the further broadcast messages at the corresponding anchor point.

In one or more embodiments, the broadcast message includes encrypted content, the encrypted content having been encrypted with a private key, and the processing unit is configured to decrypt the encrypted content using a corresponding public key.

In one or more embodiments, the broadcast message contains a broadcast timestamp, and the processing unit is configured to discard the broadcast message if the broadcast timestamp deviates from a time reference by more than a predefined threshold.

In one or more embodiments, the time reference is an internal clock value or the time reference is derived from data received over an out-of-band communication channel.

In one or more embodiments, the processing unit is configured to periodically select one of the anchor points as a master anchor point for a synchronization process between the anchor points.

According to a second aspect of the present disclosure, there is provided a positioning system for determining the geolocation of a movable object, the system comprising: a receiver configured to receive one or more broadcast messages and determine an angle of arrival of the broadcast messages; a processing unit configured to determine the geographic location using the angle of arrival of the broadcast message.

In one or more embodiments, the movable object is a vehicle.

In one or more embodiments, the navigation system comprises a positioning system of the kind set forth.

According to a third aspect of the present disclosure, a positioning method for determining the geographic position of a movable object is conceived, the method comprising: receiving, by a plurality of anchor points, a broadcast message over an ultra-wideband communication channel; determining, by a processing unit, the geographic position based on a difference between arrival times of the broadcast messages at corresponding anchors, relative positions of the anchors, and a predetermined orientation of the movable object.

According to a fourth aspect of the present disclosure, there is provided a computer program comprising executable instructions which, when executed by a positioning system, carry out a method of the kind set forth.

Drawings

Embodiments will be described in more detail with reference to the accompanying drawings, in which:

FIG. 1 shows an example of a GPS based positioning system;

FIG. 2 shows an illustrative embodiment of a positioning system;

FIG. 3 shows an exemplary embodiment of a positioning method;

FIG. 4 shows an illustrative embodiment of TDOA measurements;

FIG. 5 shows an illustrative embodiment of a UWB based positioning system;

FIG. 6 illustrates another exemplary embodiment of a UWB based positioning system;

FIG. 7 shows yet another illustrative embodiment of a UWB based positioning system;

FIG. 8 illustrates an exemplary embodiment of a UWB based navigation system;

FIG. 9 illustrates an exemplary embodiment of a state machine for selecting a primary anchor point;

FIG. 10 illustrates yet another exemplary embodiment of a UWB based positioning system.

Detailed Description

Positioning systems typically utilize satellite signals. For example, the Global Positioning System (GPS) is a satellite-based radio navigation system that provides geographic positioning and time information to a GPS receiver embedded in or attached to a moving object (e.g., a vehicle). Such systems may determine the geographic location of a mobile object. When embedded in a vehicle, the GPS receiver may, for example, enable a navigation system.

Fig. 1 shows an example of a GPS-based positioning system 100. The system 100 comprises a vehicle 102, the geographical position of which vehicle 102 should be determined by means of satellites 104, 106. Disadvantageously, the buildings 108, 110 may block the GPS signals transmitted by the satellites 104, 106. This can negatively impact the performance of the GPS-based positioning system 100.

Many automobiles include a GPS-based navigation system that can be used to determine the current location of the automobile. Such GPS-based navigation systems typically require at least 4 signals from different satellites for accurately determining the position of the car. By combining these 4 signals, a system of equations based on multipoint positioning can be set up to determine the position of the car. To achieve good positioning accuracy, all signals should be in line of sight (LOS), or at least have signal propagation times that are very close to LOS signal propagation times. Navigation may fail if the GPS signal is blocked by an obstacle such as a skyscraper. Fig. 1 shows an example of a car 102 that cannot receive signals from two satellites 104, 106 due to blockage by skyscrapers 108, 110. In underground parking lots or tunnels, the car cannot be located because the GPS signal is blocked. This means, for example, that an autonomous vehicle will not be able to park in an underground parking garage due to the lack of a reference system for locating the vehicle. Furthermore, even if GPS signals can be received, the positioning accuracy using a common GPS receiver is within the meter domain. This may be too inaccurate for some autonomous automotive applications.

Discussed now are positioning systems and corresponding positioning methods that facilitate reliable and accurate determination of the geographic location of a movable object. The movable object may be an automobile or other vehicle, such as a truck, forklift truck, bus, motorcycle, or bicycle.

Fig. 2 shows an exemplary embodiment of a positioning system 200. The positioning system 200 includes a plurality of anchor points 202, 204, 206, 208 and a processing unit 210. It should be noted that the processing unit 210 may be a separate component, or it may be integrated into one of the anchor points 202, 204, 206, 208. Further, the positioning system 200 may be embedded in or attached to a movable object, such as a vehicle. The anchor points 202, 204, 206, 208 are configured to receive broadcast messages from external broadcast devices (not shown) over an ultra-wideband (UWB) communication channel. It should be noted that an anchor point is an electronic device capable of detecting UWB pulses emitted by a UWB device (e.g., a UWB tag). To the extent that the external broadcast device has a fixed geographic location (i.e., absolute position), the external broadcast device is a static broadcast device. Further, the processing unit 210 is configured to determine the geolocation of the mobile object based on the difference between the arrival times of the broadcast messages at the corresponding anchor points 202, 204, 206, 208, the relative locations of the anchor points 202, 204, 206, 208 (i.e., the locations of the anchor points 202, 204, 206, 208 relative to each other), and the predetermined orientation of the movable object. In this way, a UWB-based positioning system may be implemented that can reliably and accurately determine the geographic location of a movable object. It should be noted that the term "movable" means that the object can move but can also be in a stationary state.

Fig. 3 shows an exemplary embodiment of a positioning method 300. The positioning method 300 comprises the following steps: at 302, broadcast messages are received by a plurality of anchor points over a UWB communication channel, and at 304, a geographic location is determined by a processing unit based on a difference between arrival times of the broadcast messages at the corresponding anchor points, relative positions of the anchor points, and a predetermined orientation of the movable object. In this way, a UWB-based positioning method can be implemented, by means of which the geographical position of a moving object can be reliably and accurately detected. It is noted that the positioning method may be at least partly implemented as a computer program.

In particular, UWB-based broadcast systems provide accurate location services that can be used indoors and outdoors. UWB broadcast-only systems have the advantage that it may not be necessary to synchronize broadcasters. The services operate independently of each other. The advantage of using UWB signals is that accurate time difference of arrival (TDOA) measurements can be achieved that can be used to establish a multipoint location based system of equations. Due to the high bandwidth of the UWB signal, the first path of the signal can be detected very accurately. Furthermore, signal reflections have little effect on the positioning system. Good first path detection is particularly important for indoor positioning systems because of the high probability of having a multi-path channel. Since all devices of the infrastructure may only need to broadcast, the broadcaster may remain very simple and no receiving unit may be needed within the broadcaster. The cost of the infrastructure is also reduced since it may not be necessary to synchronize the broadcasters.

In one or more embodiments, the processing unit is configured to determine the difference between the arrival times of the broadcast messages by: one of the anchor points is selected as a reference anchor point, and a difference between an arrival time of the broadcast message at the reference anchor point and an arrival time of the broadcast message at the other anchor point is calculated. This results in a practical and efficient implementation. Further, in one or more embodiments, the arrival time is based on a timestamp indicating a time of receipt of a predefined tag in the broadcast message. This facilitates accurate determination of the time of arrival.

FIG. 4 shows an exemplary embodiment of a TDOA measurement 400. When an anchor receives a message, it stores an exact timestamp indicating when the message was received. The timestamps received by multiple synchronized anchor points may be used to estimate the TDOA between the anchor points. Fig. 4 shows a timing diagram of TDOA measurements based on a broadcast message and three receive anchors 404, 406, 408. One of the anchor points is selected as a reference anchor point. In this case, anchor point 406 (anchor point 4) is the anchor point that serves as the time reference for TDOA measurements. Based on the time of receipt of the predefined tag in the UWB message, a timestamp may be stored and compared to the timestamp of the reference anchor point.

In one or more embodiments, the processing unit is configured to receive data indicative of a predetermined orientation of the movable object from the inertial measurement unit. The inertial measurement unit may be comprised in the positioning system and/or in the same device or object in which the positioning system is comprised. The use of an inertial measurement unit facilitates the predetermination of the orientation of the movable object. Thus, depending on e.g. available sensors in the car, the received broadcast time stamp can be combined with data received from an Inertial Measurement Unit (IMU) in the car, which combination can give feedback on the orientation of the car.

Fig. 5 shows an exemplary embodiment of a UWB-based positioning system 500. The positioning system 500 comprises a plurality of anchor points 504, 506, 508 of the kind set forth and a processing unit (not shown). A plurality of anchor points 504, 506, 508 and a processing unit are included in the car 502. Although in this schematic overview the anchor points 504, 506, 508 are located at the corners of the car 502, the skilled person will appreciate that the anchor points 504, 506, 508 may be located at more suitable locations within the car 502. The anchors 504, 506, 508 are configured to receive broadcast messages from an external broadcast device 510. In particular, a minimum of three anchor points 504, 506, 508 may be required to locate the car 502. If data from more anchor points 504, 506, 508 is available, redundancy is added to the system 500, which results in better measurement accuracy and fault tolerance. Thus, in one or more embodiments, the plurality of anchors includes three or more anchors. For simplicity, the boundaries of the car 502 are oriented along the X-axis and Y-axis of the coordinate system. In this example, the orientation of the car 502 is known, for example, because the car 502 was tracked or measured by the IMU during navigation. The anchor points 504, 506, 508 on the automobile are synchronized by wired or wireless synchronization techniques. When the broadcaster transmits a message, each anchor point attached to car 502 receives the message and generates a receive timestamp. These receive timestamps may be combined with the known relative positions of the anchor points 504, 506, 508 and the absolute position of the broadcast device 510. The combined information may be used to set up a system of equations for determining the location of the automobile 502.

For example, the following system of equations may be set based on the absolute positions of the anchor point and the broadcast device:

1_A4-BC.. distance X between broadcaster and A4_BC.. X coordinate of BC

1_A3-BC.. distance Y between broadcaster and A3_BC.. Y coordinate of BC

1_A2-BC.. distance Z between broadcaster and A2_BC... Z coordinate of BC

X_A4.. X coordinate of A4_A3.. X coordinate of A3_A2.. X coordinate of A2

Y_A4... Y coordinate of A4_A3... Y coordinate of A3_A2.. Y coordinate of A2

Z_A4... Z coordinate of A4_A3... Z coordinate of A3_A2... Z coordinate of A2

Some simplification can be made based on the known geometry of the car and the placement of the anchor points. The variables for the length and width of the car are just placeholders. In practical systems, anchor points may not be placed at the corners of the car; in this case, the distance between anchor points needs to be considered rather than the car length and width. The Z coordinate of the anchor point is known due to the known car height and the known anchor point placement. Depending on the shape of the car, anchor points may be placed at different heights. In this case, the position of the car can be estimated as long as the height is known to the system. In this example, the following simplifications may be made:

X_AP3＝X_AP4+C_{length of}

Y_AP3＝Y_AP4

X_AP2＝X_AP4

Y_AP2＝Y_AP4+C_{Width of}

Z_AP2＝Z_AP3＝Z_AP4 C_{Length of}.. length of car

C_{Width of}.. width of automobile

By combining all these equations, the system of equations shown below can be derived. Variable Δ l_A3And Δ l_A2Is the placeholder for TDOA for A3 compared to a4 and a2 compared to a4, multiplied by the signal propagation speed. These TDOAs may be measured by the synchronous anchor system. Unknown variables in the equation set are labeled with parentheses. Only two different variables are unknown. This means that the system of equations can be solved and the position of the car can be estimated knowing the orientation of the car.

Fig. 6 illustrates another exemplary embodiment of a UWB-based positioning system 600. If the orientation of the vehicle is unknown, the system of equations cannot be solved because the same TDOA can result in multiple locations. Fig. 6 shows an example of a system 600 consisting of a broadcaster 604 and a car 602 with three attachment anchors. The distances between the car and the anchor points are referred to as d1, d2, and d 3. It should be appreciated that the distance between the broadcaster 604 and the anchor point is the same even though the cars 602 have different locations. Essentially, each position of the car 602 with the anchor point on the dashed line would result in the same distance between the broadcaster 604 and the anchor point. Thus, the automobile 602 cannot determine its location without knowing its orientation.

If the orientation is known, the position of the car can be determined completely unambiguously by using the equation shown above. The system of equations should be adjusted according to the orientation of the car. For example, if the car is rotated 45 ° clockwise, the system of equations (equations 1-4) should be adjusted as shown below. These changes should also be considered in the equations shown above. Regardless of the adjustment, the system of equations still has only two unknown variables, which means that it is solvable.

X_AP3＝X_AP4+C_{Length of}*cos(45°) (1)

Y_AP3＝Y_AP4+C_{Length of}*sin(-45°) (2)

X_AP2＝X_AP4+C_{Width of}*sin(45°) (3)

Y_AP2＝X_AP4+C_{Width of}*cos(45°) (4)

The orientation of the car can be determined using an Inertial Measurement Unit (IMU) which provides information about the absolute orientation of the car, for example by means of a magnetometer. If such an IMU based system is not available, the vehicle can be located by combining the TDOA measurements of the two broadcasters. Thus, in one or more embodiments, each anchor point is configured to receive a further broadcast message over the ultra-wideband communication channel, and the processing unit is configured to determine the orientation of the moveable object based on the difference between the arrival times of the broadcast messages at the corresponding anchor points and the difference between the arrival times of the further broadcast messages at the corresponding anchor points.

Fig. 7 shows yet another illustrative embodiment of a UWB-based positioning system 700. The system includes two broadcast devices 704, 706 configured to broadcast messages to three anchor points attached to a car 702. If the measurements of the two broadcasters 704, 706 are combined, the car 702 can be located because there is only one intersection point for the possible car position calculated based on the received broadcast message. For example, location 1 and location 1' are examples of locations calculated based on a single broadcast. However, these locations do not match. The calculated position 2 and position 2' are the only matching positions. Thus, there is only one possible solution. This means that the position of the car 702 can be estimated unambiguously by combining the message timestamps of the two broadcasters 704, 706. The received broadcast message has a time offset since both broadcast devices 704, 706 will not be able to transmit in full synchronization. This time offset can be compensated for in a post-processing step, in particular when post-processing the measured data.

In one or more embodiments, the broadcast message includes encrypted content, wherein the encrypted content has been encrypted with a private key, and the processing unit is configured to decrypt the encrypted content using a corresponding public key. In this way, tampering with the broadcast message becomes more difficult. Thus, the transmitted broadcast may contain unencrypted content, e.g., for insecure applications, or the content may be encrypted to form a root of trust. If encryption is applied, an asymmetric encryption scheme should be used, since cars receiving the broadcast should only be able to decrypt the broadcast. If symmetric encryption is to be applied, any device that is capable of decrypting the broadcast will also be able to transmit the broadcast, which should be avoided. When applying the asymmetric scheme, each broadcasting device has a different private key for encrypting messages. In addition, each car has a public key of the broadcaster for decrypting the received content. The encrypted content may also be verified and authenticated if the broadcast content also contains a hash and a timestamp. If the attacker does not know the private key, the attacker can only change the ciphertext. If the attacker has changed the ciphertext, the decrypted hash and plaintext will no longer match. If the broadcast message also contains a timestamp, the message can only be reused for a predefined amount of time until the car notices that an attacker reuses the message in order to fake the role of the broadcaster. To compare the timestamps, the car may use an internal clock or an external clock as a time reference. Thus, in one or more embodiments, the broadcast message contains a broadcast timestamp, and the processing unit is configured to discard the broadcast message if the broadcast timestamp deviates from the time reference by more than a predefined threshold. In this way, the safety protection level is improved.

Fig. 8 illustrates an exemplary embodiment of a UWB-based navigation system 800. The UWB-based navigation system includes a plurality of anchor points 802, 804, 806, a post-processing unit 808, an internal reference clock 810, an additional physical layer (PHY) interface, and a position reporting system 814. The reported position may in turn be used by a navigation module (not shown) that calculates a route from the reported position to a destination. The post-processing unit 808 processes the signal outputs generated by the anchor points 802, 804, 806 and transmits the results of the processing to the location reporting system 814. Post-processing unit 808 thus represents a processing unit of the kind set forth. If a broadcast is received, it can be decrypted and the timestamp contained in the plaintext can be extracted. This timestamp may be compared to an internal reference clock 810. If the difference between the internal clock value and the broadcast timestamp is too large, the message is discarded. If the timestamp matches the internal clock value, the post-processing unit 808 may begin calculating the geolocation of the automobile. This PHY interface 812 may also be used to generate a time reference instead of the internal reference clock 810, based on data received by the additional PHY interface 812. Thus, in one or more embodiments, the time reference is an internal clock value of the time reference derived from data received over the out-of-range communication channel (e.g., the additional PHY interface 812). An advantage of using the additional PHY interface 812 is that the time reference will not be affected by drift of the internal reference clock 810, which results in a more accurate time base for the system 800. Thus, there will be less time left for an attacker to reuse an already existing broadcast.

Fig. 9 illustrates an exemplary embodiment of a state machine 900 for selecting a primary anchor. If the anchor points are synchronized wirelessly, it is important that each anchor point is in line of sight with the master anchor point. For such wireless synchronization, the master anchor typically transmits a time reference beacon to the other anchors. If an anchor cannot receive beacons, it cannot be used for TDOA measurements due to the drifting clock within the anchor. To avoid this, the processing unit may be configured to periodically select one of the anchor points as a primary anchor point for synchronous processing between the anchor points. By periodically selecting a new master anchor, an optimal anchor for transmitting beacons may be selected (i.e., an anchor for which all other anchors are likely to receive beacons). Fig. 9 shows an example of how the optimal anchor point for wireless synchronization may be estimated. If too many erroneous measurements occur during UWB navigation, then inter-anchor TOF measurements are initiated. Based on the TOF measurements, the channel and corresponding first path propagation delay may be estimated. Based on the known first path propagation time and the Channel Impulse Response (CIR), an optimal anchor point for wireless synchronization may be determined. If an anchor point has been selected, UWB-based navigation may begin again. If too many errors occur during navigation, the channel is likely to change and the process of determining the best anchor point for wireless synchronization should be repeated.

Fig. 10 shows yet another illustrative embodiment of a UWB-based positioning system 1000. Instead of a TDOA-based positioning system of the kind set forth, an angle of arrival (AOA) -based positioning system can be envisaged. In its basic form, this AOA-based positioning system includes: a receiver configured to receive one or more broadcast messages and determine an angle of arrival of the broadcast messages; and a processing unit configured to determine a geographic location using the angle of arrival of the broadcast message. This AOA-based positioning system represents an alternative solution to the problem of how to facilitate reliable and accurate determination of the geolocation of a moving object.

Fig. 10 shows an example of an AOA-based positioning system 1000 comprising three broadcasters 1004, 1006, 1008 and an AOA device 1002. The AOA device 1002 receives broadcast messages sent by the broadcast apparatuses 1004, 1006, 1008 and measures the angle of arrival of the received signals. The position of AOA device 1002 may be estimated using triangulation techniques. It should be noted that for a two-dimensional angle-of-arrival measurement, the delays of different broadcast messages should also be taken into account. If a two-dimensional angle-of-arrival measurement is made, three broadcasters will be required to resolve each context ambiguity. If a three-dimensional angle of arrival can be measured, one broadcast is sufficient for localization if the angle of arrival data is combined with the data provided by the inertial measurement unit. Otherwise, similar to the TDOA system, two different broadcasts should be combined, and also time migration between broadcasts should be considered.

The systems and methods described herein may be implemented, at least in part, by a computer program or computer programs that may exist in a variety of forms, both activated and deactivated, in a single computer system or across multiple computer systems. For example, they may exist as software program(s) comprised of program instructions in source code, object code, executable code or other formats for performing some steps. Any of the above formats may be embodied in compressed or uncompressed form on a computer readable medium, which may include storage devices and signals.

As used herein, the term "computer" refers to any electronic device that includes a processor, such as a general purpose Central Processing Unit (CPU), a special purpose processor, or a microcontroller. A computer is capable of receiving data (input), of performing a series of predetermined operations on the data, and of producing results (output) in the form of information or signals. The term "computer" will, depending on the context, mean, in particular, a processor or, more generally, a processor associated with a single chassis or assembly of related elements housed within a housing.

The term "processor" or "processing unit" refers to a data processing circuit that may be a microprocessor, a coprocessor, a microcontroller, a microcomputer, a central processing unit, a Field Programmable Gate Array (FPGA), a programmable logic circuit, and/or any circuit that controls signals (analog or digital) based on operational instructions stored in a memory. The term "memory" refers to a storage circuit or circuits, such as read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, cache memory, and/or any circuit that stores digital information.

As used herein, a "computer-readable medium" or "storage medium" can be any means that can contain, store, communicate, propagate, or transport the computer program for use by or in connection with the instruction execution system, apparatus, or device. The computer readable medium can be, for example but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CDROM), a Digital Versatile Disc (DVD), a blu-ray disc (BD), and a memory card.

It should be noted that the above embodiments have been described with reference to different subject matters. In particular, some embodiments may have been described with reference to method class claims, while other embodiments may have been described with reference to device class claims. However, a person skilled in the art will gather from the above that, unless other notified, in addition to any combination of features belonging to one type of subject-matter also any combination of features relating to different subject-matters, in particular combinations of features of the method class of claims and features of the apparatus class of claims, is considered to be disclosed with this document.

Further, it should be noted that the drawings are schematic. In the different drawings, similar or identical elements are denoted by the same reference numerals. Furthermore, it should be noted that in order to provide a concise description of the exemplary embodiments, implementation details may not be described which would ordinarily be within the skill of the art. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

Finally, it should be noted that the skilled person will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim. The indefinite article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The measures recited in the claims can be implemented by means of hardware comprising several distinct elements, and/or by means of a suitably programmed processor. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

List of reference numerals

100 GPS-based positioning system

102 vehicle

104 satellite

106 satellite

108 building

110 building

200 positioning system

202 anchor point

204 anchor point

206 anchor point

208 anchor point

210 processing unit

300 positioning method

302 receiving broadcast messages over a UWB communication channel by a plurality of anchor points

304 determining, by the processing unit, a geolocation of the movable object based on a difference between arrival times of the broadcast messages at corresponding anchors, relative locations of the anchors, and a predetermined orientation of the movable object

400 TDOA measurements

402 broadcast equipment

404 anchor point

406 anchor point

408 anchor point

410 time stamping

412 difference between arrival times

414 time of arrival

500 UWB-based positioning system

502 automobile

504 anchor point

506 anchor point

508 anchor point

510 broadcast apparatus

600 UWB-based positioning system

602 automobile

604 broadcasting equipment

700 UWB based positioning system

702 vehicle

704 broadcasting equipment

706 broadcast apparatus

800 UWB-based navigation system

802 anchor point

804 anchor point

806 anchor point

808 post-processing unit

810 internal reference clock

812 additional physical layer interface

814 position reporting system

900 state machine for selecting a primary anchor

902 inter-anchor time-of-flight measurement

904 channel impulse response estimation

906 primary anchor negotiation

908 begin UWB-based navigation

910 wait for erroneous measurements

1000 UWB-based positioning system

1002 angle of arrival device

1004 broadcast equipment

1006 broadcasting equipment

1008 broadcasting the device.