Patent Publication Number: US-2017369006-A1

Title: Position-based performance of a vehicle function in a vehicle communication system

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/894,527, filed Nov. 29, 2015, which itself is a 35 U.S.C. §371 national stage application of PCT Application No. PCT/EP2014/061210, filed on May 29, 2014, which claims priority from Great Britain Patent Application No. 1309744.9, filed on May 31, 2013, the contents of which are incorporated herein by reference in their entireties. The above-referenced PCT International Application was published in the English language as International Publication No. WO 2014/191537 A1 on Dec. 4, 2014. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a vehicle communication system for facilitating control over vehicle functions. The present invention relates more particularly, but not exclusively, to systems and methods for facilitating control over vehicle functions based, at least in part, on position of a mobile communication unit. Aspects of the invention relate to a system, to a method and to a vehicle. 
     BACKGROUND OF THE INVENTION 
     In today&#39;s world, many vehicles are equipped with systems for facilitating remotely controlled vehicle functions such as passive entry and passive starting (i.e., PEPS) of a host vehicle. When a vehicle is equipped with a PEPS system, a user may carry a mobile communication unit which can communicate with a base station located in the vehicle. To initiate communication, the base station may emit a relatively powerful Low Frequency (LF) electromagnetic field, causing a mobile communication unit that is sufficiently close to the base station to awaken. Once the mobile communication unit is awake, it may use Radio Frequency (RF) transmissions to dispatch signals, which may be validated by the base station. If the base station recognizes and approves the identity of the mobile communication unit, (i.e., the base station authenticates the mobile communication unit), the base station may facilitate the performance of a predefined vehicle function, such as actuating a door lock mechanism, causing the door to become unlocked. In such passive systems, the functions may be performed based solely on the position, or changes in the position, of the mobile communication unit, and the functions may be performed even though no specific command may have been initiated by the user. 
     For example, in some passive systems, an approach of the mobile communication unit toward the vehicle may be detected so that a desire for one or more vehicle functions to be performed (e.g., unlocking doors) may be anticipated and automatically provided in a manner that enhances the operator experience. In other passive systems, a departure of the mobile communication unit away from the vehicle may be detected so that one or more other functions (e.g., locking vehicle doors) may be performed. 
     In addition to the above-described passive communications, a vehicle communication system may also be configured to facilitate active communications among system components. Active communications may include transmissions initiated by a user seeking performance of a pre-defined function. For example, a user, by pressing a button or actuating a switch on a mobile communication unit, may actively initiate active communications with the vehicle, sending a command to lock or unlock the vehicle doors or to actively start the vehicle engine. 
     Unfortunately, by facilitating such active interactions, a vehicle communication system may increase the possibility for a user to submit an unintentional or inadvertent communication input via the mobile communication unit. If the user is in a position to observe the inadvertent instruction being performed, the user may correct the error by issuing a counteracting request. If the user is not so advantageously positioned, however, no corrective action may be initiated, and an undesirable consequence may occur. For example, if a mobile communication unit were configured with a button for sounding an alarm on the vehicle, and if a user were to inadvertently press the button while being situated so as to be unable to hear the alarm, yet within range for the command to be received by a base station in the vehicle, the alarm may be unintentionally activated without the knowledge of the user. 
     While such events are annoying, they may not be nearly as wasteful as having the vehicle engine running all day long while the user unknowingly conducts a full day of affairs in a nearby office. One can envision more damaging consequences where the mobile communication unit is configured for enabling a user to remotely open the vehicle windows. Thus, it would be advantageous to have a vehicle communication system that provides for active communications with a vehicle and control over vehicle functions, while also decreasing the likelihood of dispatching inadvertent or unintentional commands to be performed by the vehicle. 
     The present invention attempts to address or ameliorate at least some of the above problems associated with vehicle communication systems. 
     SUMMARY OF THE INVENTION 
     In one aspect, the present invention provides a vehicle communication system for facilitating control over a function of a vehicle comprising a base station positioned in the vehicle and a mobile communication unit. The base station comprises a first transmitter for transmitting a signal to the mobile communication unit and, a first receiver for receiving a signal from the mobile communication unit. The base station is configured to receive a first request from the mobile communication unit, wherein the first request seeks performance of a first vehicle function. The base station is also configured to determine a position of the mobile communication unit relative to the vehicle and to compare the position of the mobile communication unit relative to the vehicle to a first criteria. Finally, the base station is configured to facilitate performance of the first vehicle function if the position of the mobile communication unit relative to the vehicle satisfies the first criteria. 
     The base station may be configured to determine the position of the mobile communication unit relative to the vehicle based on a time of flight method. The first transmitter may be an ultra-wideband transmitter and the first receiver may be an ultra-wideband receiver. It is a particular advantage of ultra-wide communications that it is possible to distinguish between signals which travel along a direct path between transmitter and receiver and those which follow non-direct paths. Accordingly, this allows the position of the mobile communication unit relative to the vehicle to be established with a high degree of accuracy, much more so than distance measurements in conventional narrow-band systems which typically rely on radio signal strength intensity (RSSI) measurements. 
     The base station may be configured to facilitate performance of the first vehicle function only if the position of the mobile communication unit satisfies the first criteria. In one embodiment, the first criterion requires that the position be less than a first distance from the vehicle. In another alternative embodiment, the first criterion requires that the position be greater than a first distance from the vehicle. 
     In another embodiment, the base station is configured to receive a second request from the mobile communication unit, wherein the second request seeks performance of a second vehicle function. In this embodiment, the base station is configured to compare the position of the mobile communication unit relative to the vehicle to a second criteria and to facilitate performance of the second vehicle function if the position of the mobile communication unit relative to the vehicle satisfies the second criteria. The base station may be configured to facilitate performance of the first vehicle function only if the position of the mobile communication unit satisfies the first criteria, and may also be configured to facilitate performance of the second vehicle function only if the position of the mobile communication unit satisfies the second criteria. The first criterion may require that the position be within a first distance from the vehicle, and the second criterion may require that the position be within a second distance from the vehicle. The first distance may be greater than the second distance. 
     In another embodiment, a vehicle communication system includes a base station that is configured to receive a third request from the mobile communication unit, the third request seeking performance of a third vehicle function. In this embodiment, the base station is configured to compare the position of the mobile communication unit relative to the vehicle to a third criterion and facilitate performance of the third vehicle function if the position of the mobile communication unit relative to the vehicle satisfies the third criteria. 
     In an embodiment, the base station is configured to facilitate performance of the first vehicle function only if the position of the mobile communication unit satisfies the first criteria, to facilitate performance of the second vehicle function only if the position of the mobile communication unit satisfies the second criteria, and to facilitate performance of the third vehicle function only if the position of the mobile communication unit satisfies the third criteria. The first criteria may require that the position be within a first distance from the vehicle, the second criteria may require that the position be within a second distance from the vehicle, and the third criteria may require that the position be within a third distance from the vehicle. The first distance may be greater than the second distance, and the second distance may be greater than the third distance. 
     In an embodiment, the first vehicle function comprises locking an aperture of the vehicle, the second vehicle function comprises starting an engine of the vehicle, and the third vehicle function comprises opening an aperture of the vehicle. The third vehicle function may also comprise closing an aperture of the vehicle. 
     In another aspect, a method for facilitating control over a function of a vehicle comprises providing a base station positioned in the vehicle and a mobile communication unit, wherein the base station comprises a first transmitter for transmitting a signal and a first receiver for receiving a signal from the mobile communication unit. The method also includes receiving a first request from the mobile communication unit, wherein the first request seeks performance of a first vehicle function, and determining a position of the mobile communication unit relative to the vehicle. Finally, the method includes comparing the position of the mobile communication unit relative to the vehicle to a predetermined first criteria and facilitating performance of the first request if the position of the mobile communication unit relative to the vehicle satisfies a first criteria. 
     Determining the position of the mobile communication unit relative to the vehicle may be based on a time of flight method. The first transmitter may be an ultra-wideband transmitter and the first receiver may be an ultra-wideband receiver. 
     In another embodiment, a method for facilitating control over a function of a vehicle further comprises receiving a second request from the mobile communication unit, wherein the second request seeks performance of a second vehicle function. Still further, the method comprises comparing the position of the mobile communication unit relative to the vehicle to a second criteria and facilitating performance of the second vehicle function if the position of the mobile communication unit relative to the vehicle satisfies the second criteria. 
     In a further embodiment, a method for facilitating control over a function of a vehicle also includes receiving a third request from the mobile communication unit, wherein the third request seeks performance of a third vehicle function —  The position of the mobile communication unit relative to the vehicle is compared to a third criterion, and performance of the third vehicle function is facilitated if the position of the mobile communication unit relative to the vehicle satisfies the third criteria. 
     In another aspect of the invention, a vehicle may be provided having a vehicle communication system, or being adapted to perform a method, as described in the preceding paragraphs of this section. 
     Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. For example, features described in connection with one embodiment are applicable to all embodiments unless such features are incompatible. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       One or more embodiments of the present invention will now be described, by way of example only, with reference to the accompanying figures, in which: 
         FIG. 1  shows a schematic representation of a vehicle communication system according to an embodiment of the present invention; 
         FIG. 2  shows the installation of the base station and transceivers of the vehicle communication system according to one embodiment of the present invention in a motor vehicle; 
         FIG. 3  shows an operating mode of the vehicle communication system according to one embodiment of the present invention; 
         FIG. 4  illustrates another operating mode of the vehicle communication system according to one embodiment of the present invention; 
         FIG. 5  illustrates another operating mode of the vehicle communication system according to one embodiment of the present invention; and 
         FIG. 6  illustrates another operating mode of the vehicle communication system according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a vehicle communication system  100  in accordance with an embodiment of the present invention. The vehicle communication system  100  is configured to facilitate transfer of information among components of the vehicle communication system  100 , which may further facilitate control over one or more functions of a vehicle  102 . Exemplary functions that may be controlled include, but are not limited to, enhanced Passive Entry and Passive Start (ePEPS) keyless access, remote engine start, remote opening and closing of vehicle apertures, deployment and retraction of external mirrors or antennas, and/or activation and deactivation of lighting and signalling systems of the vehicle  102 . 
     The vehicle communication system  100  will be described with reference to the vehicle  102  which has a front right door  142 , a rear right door  144 , a front left door  146  and a rear left door  148 . The vehicle  102  also has a boot lid  150  (also known as a deck lid) which can be locked/unlocked by the vehicle communication system  100  but this is not described herein for the sake of brevity. The doors  142 - 148  each have a lock mechanism and an external handle; and the front doors  142 ,  146  each have a folding door mirror. The lock mechanisms each comprise a door lock switch to provide a locking signal to indicate the status of the respective lock mechanism. 
     The vehicle communication system  100  comprises a base station  104  to be installed in the vehicle  102  to provide a Remote Function Actuator (RFA) for the vehicle  102 . The base station  104  comprises an electronic control unit  106  and a first rechargeable battery  108 . The electronic control unit  106  comprises a memory storage device  107  that is in communication with one or more processor(s)  109 . The processor(s)  109  can be configured to perform computational operations in accordance with instructions (e.g., software) stored in the memory storage device  107 . The first rechargeable battery  108  provides a dedicated power supply for the base station  104  to enable its operation independently from a vehicle power system (not shown). 
     The base station  104  further comprises first, second and third ultra-wideband transceivers  110 ,  112 ,  114 . The first transceiver  110  is provided proximal the electronic control unit  106 . The second and third transceivers  112 ,  114  are positioned in the vehicle  102  remote from the electronic control unit  106  and connected via a dedicated local interconnect network (LIN)  116 . The transceivers  110 ,  112 ,  114  each have an integrated antenna. As discussed more fully below, the vehicle communication system  100  may further comprise a fourth transceiver (not shown) which is also positioned in the vehicle  102  remote from the electronic control unit  106  and connected via the dedicated local interconnect network (LIN)  116 . 
     The base station  104  is connected to the vehicle systems (denoted generally by the reference numeral  118 ) via a CAN bus  120 . The base station  104  can thereby receive signals from the vehicle systems (e.g., locking signals from door lock switches); and can control operation of one or more vehicle systems (e.g., door lock mechanisms, closure systems for vehicle apertures such as windows, sun roof, ventilation systems, deck lid, engine start/ignition, vehicle lighting, entertainment systems, horn, heater, air conditioning, and the like). The CAN bus  120  can also be employed to convey instructions from the electronic control unit  106  to other systems (e.g., actuators, controls) of the vehicle  102 , such as the engine control unit, to facilitate enabling and/or disabling of one or more vehicle systems (e.g., passive engine starting). 
     The vehicle communication system  100  further comprises a mobile communication unit  122  having a remote ultra-wideband transceiver  124  and a second rechargeable battery  126 . The mobile communication unit  122  is portable to facilitate its being carried by the user. As described herein, the mobile communication unit  122  communicates with the base station  104  to facilitate control over vehicle functions, such as passive entry to the vehicle  102 , and, under some circumstances, to provide information to a user in possession of the mobile communication unit  122 . 
     The base station  104  further comprises a dock  128  for receiving the mobile communication unit  122 . The dock  128  has a port  130  to enable communication between the base station  104  and the mobile communication unit  122 . A charging pad  132  is also provided in the dock  128  to facilitate charging of the second rechargeable battery  126  when the mobile communication unit  122  is docked and thus mated with the charging pad  132 . A bi-colour light emitting diode  134  is provided in the dock  128  to indicate the status of the mobile communication unit  122  (for example to indicate that the second rechargeable battery  126  is charging or is fully charged). The charging pad  132  is connected to a power supply unit (PSU) provided in the base station  104 . An external charge port  136  for the base station  104  is provided for charging the first rechargeable battery  108 . 
     The installation of the vehicle communication system  100  is illustrated in  FIG. 2 . The base station  104  and the first transceiver  110  are located at the rear of the vehicle  102  and the second and third transceivers  112 ,  114  are located in the upper part of the vehicle  102  (typically in the roof) on the right and left sides respectively of the vehicle  102 . As illustrated by dashed lines in  FIG. 2 , the transceivers  110 ,  112 ,  114  communicate with the mobile communication unit  122 . The distance from each of the first, second and third transceivers  110 ,  112 ,  114  to the remote transceiver  124  can be determined by measuring transmission and/or response time (for example, time of flight for a signal transmission) thereby allowing the position of the mobile communication unit  122  in relation to the vehicle  102  to be determined through triangulation. The use of ultra-wideband frequencies (typically greater than 3 GHz) allows the position of the mobile communication unit  122  to be tracked with a relatively high degree of accuracy. 
     In accordance with such an embodiment of the vehicle communication system  100 , wherein the base station  104  comprises three transceivers  110 ,  112 ,  114  disposed at spaced-apart positions within the vehicle  102 , it is possible to use the transmission and/or response times for communications sent between the mobile communication unit  122  and each of the transceivers  110 ,  112 ,  114  to determine a position of the mobile communication unit  122  relative to the vehicle  102  along each of two axes. For example, with the base station  104  and the first transceiver  110  located toward the rear of the vehicle  102  and with the second and third transceivers  112 ,  114  disposed within the roof (on respective left and right sides), the position of the mobile communication unit  122  relative to the vehicle  102  can readily be determined, i.e. as shown in the plan view of  FIGS. 2 to 6 . 
     However, with the second and third transceivers  112 ,  114  disposed in the vehicle roof, and therefore lying in the same horizontal plane, there may be situations in which it is not possible to readily determine the position of the mobile communication unit  122  along a direction normal to the plan views of  FIGS. 2 to 6  (i.e., above or below the vehicle  102 ). Accordingly, in a further embodiment of the invention, the vehicle communication system  100  may comprise a fourth transceiver (not shown) which is disposed within the vehicle  102  at a position that is spaced apart in a vertical direction from both the plane of the vehicle roof and the horizontal plane in which the base station  104  lies. For example, the fourth transceiver (not shown) could be mounted in the vehicle dashboard on the vehicle center line. With this configuration, the height of the mobile communication unit  122  relative to the vehicle  102  can readily be determined. 
     Thus, a position of the mobile communication unit  122  relative to the vehicle  102  may be periodically or continuously determined and may be saved in the memory storage device  107  for subsequent retrieval and analyses by the processor  109  in accordance with instructions that are also stored in the memory storage device  107  or pre-programmed into the processor  109 . Such monitoring and storing and processing of position information may be useful for observing, tracking, and identifying not only positions of the mobile communication unit  122 , but also certain rates, patterns, and/or characteristics of changes in those positions (i.e., movements of the mobile communication unit  122 ). Accordingly, the vehicle communication system  100  may be configured to detect an approach of the mobile communication unit  122  toward an authorization zone  138  defined relatively to the vehicle  102 , to detect a departure of the mobile communication unit  122  from the authorization zone  138 , to detect a continuing presence of the mobile communication unit  122  within the authorization zone  138 , and to recognize patterns involving combinations of approaches, departures, and prolonged presences relative to the authorization zone  138  of the vehicle  102 . In addition, the vehicle communication system  100  may be configured to determine a position of the mobile communication unit  122  relative to the vehicle  102  and to compare that relative position to one or more predetermined (or learned) criteria. The results of that comparison may then be used by the vehicle communication system  100  in determining whether and how to transmit further communications or to facilitate performance of certain vehicle functions. 
     The remote transceiver  124  of the mobile communication unit  122  transmits a polling signal which, when received by the first transceiver  110  of the base station  104 , initiates communication between the base station  104  and the mobile communication unit  122 . In one embodiment, upon receipt of the polling signal, the first transceiver  110  responds by transmitting a challenge signal. The challenge signal is received by the mobile communication unit  122  and prompts the mobile communication unit  122  to transmit a response signal. The electronic control unit  106  receives the response signal and attempts to determine whether it was sent by an authorized device (i.e., to validate or authenticate the mobile communication unit  122 ). 
     If the response signal is authenticated, the electronic control unit  106  continues to communicate with the mobile communication unit  122  and tracks its position in relation to the vehicle  102  and may store the position information in the memory storage device  107  for retrieval and processing by the processor  109  in accordance with pre-defined instructions. Moreover, provided the challenge/response sequence is completed successfully, the electronic control unit  106  will provide control over functions of the vehicle  102  subject to satisfaction of operating criteria. If the response signal is not authenticated, the electronic control unit  106  will not facilitate user control over vehicle functions, such as unlocking the doors of vehicle  102  or starting the engine of vehicle  102 . 
     In one mode of operation, the polling signal is transmitted continually by the remote transceiver  124  so that communication with the base station  104  is initiated by the mobile communication unit  122 . Accordingly, the vehicle communication system  100  can initiate a challenge/response cycle without the need for user interaction, such as actuating a door handle. 
     In another mode of operation, such as may be active upon first entry of the vehicle  102  into service, to conserve energy stored in the second rechargeable battery  126 , the polling signal is transmitted for an operating period of thirty (30) days. The transmission of the polling signal is stopped if the mobile communication unit  122  does not establish communication with the base station  104  during the operating period. A button provided on the mobile communication unit  122  can be pressed to re-commence transmission of the polling signal after said operating period has expired. 
     In another embodiment, the polling signal is transmitted intermittently, rather than continuously. In accordance with this embodiment, the polling signal is repeated during the operating period with a time interval between transmission cycles (pulses), i.e. the polling signal is transmitted periodically during the operating period. The time interval between the transmission cycles can be modified in response to measured parameters. For example, the time interval between transmissions can be modified depending on the measured distance between the vehicle  102  and the mobile communication unit  122 . For example, if the mobile communication unit  122  is close to the vehicle  102 , the time interval can be reduced to one (1) second. Conversely, if the mobile communication unit  122  is relatively far away from the vehicle  102 , the time interval can be increased to five (5) seconds. 
     The base station  104  and the mobile communication unit  122  can communicate with each other over a range of at least 20 metres. The authorization zone  138  is defined within the communication range. For example, the authorization zone  138  may be defined as having a radius of  2  metres around the vehicle  102 . When the electronic control unit  106  determines that the mobile communication unit  122  is inside the authorization zone  138 , the base station  104  may facilitate automatic unlocking of one or more of the vehicle&#39;s doors  142 - 148 . Conversely, when the electronic control unit  106  determines that the mobile communication unit  122  is outside the authorization zone  138 , the base station  104  may cause the automatic locking of the vehicle&#39;s doors  142 - 148 . 
     As discussed above, a vehicle communication system  100  comprising three or fewer transceivers may be able to determine a position of the mobile communication unit  122  relative to the vehicle  102  along only two axes. Accordingly, the authorization zone  138  may be defined in terms of only those two axes. A vehicle communication system  100  comprising four or more transceivers, however, may be able to determine a position of the mobile communication unit  122  relative to the vehicle  102  along any combination of three (optionally orthogonal) axes. Accordingly, the dimensions of the authorization zone  138  may be defined in terms positions along each of the three axes, such that the authorization zone  138  (and thus the set of positions that are outside the authorization zone  138 ) may be defined in terms of three-dimensional space relative to the vehicle  102 . 
     Being able to accurately determine the position of the mobile communication unit  122  in a three-dimension space around the vehicle  102  may be particularly useful in certain situations, for example when the vehicle  102  is parked in a multi-level or multi-story car park or adjacent to a multi-story building. In such situations it is possible that the driver, having exited the vehicle  102  may move to another level of the car park or building above or below the vehicle  102 , but may still be sufficiently close to the vehicle  102  to be within the authorization zone  138 , resulting in one or more of the vehicle doors being automatically unlocked. 
     Accordingly, if it is determined that the mobile communication unit  122  is disposed sufficiently above or below the vehicle  102 , such as in the example of the multi-level car park, the electronic control unit  106  may use that position information, if it is known, to not unlock the vehicle doors even when the mobile communication unit  122  would otherwise be judged to be within an authorization zone  138  defined in only two dimensions. 
     The electronic control unit  106  may be configured to operate the vehicle communication system  100  according to a number of operating modes. In a number of scenarios, the mobile communication unit  122  is carried on the person of the user and therefore follows the movements of the user. In the accompanying figures, movement paths of the user, and therefore, the mobile communication unit  122 , are illustrated by a set of footprints  140 . The process performed by the base station  104  for authenticating the mobile communication unit  122  is the same as described above and is common to each of the operating modes. 
     In particular, the remote transceiver  124  transmits a polling signal which initiates an authentication cycle with the first transceiver  110 . The base station  104  transmits a challenge signal which triggers transmission of a response signal from the mobile communication unit  122 . The electronic control unit  106  validates the response signal and, if successful, the base station  104  tracks the range and position of the authenticated mobile communication unit  122 . If the authentication cycle is not successfully completed, for example due to an incorrect response signal being sent from the mobile communication unit  122 , the function will not be performed (e.g., the doors  142 - 148  will not be unlocked), and the vehicle  102  will not respond to commands dispatched from the mobile communication unit  122 . 
     The electronic control unit  106  may be configured to operate the vehicle communication system  100  according to a first operating mode as illustrated in  FIG. 3 . In this operating mode, the vehicle communication system  100  operates to unlock the doors  142 - 148  on the side of the vehicle  102  on which the user approaches with the mobile communication unit  122 . Having authenticated the mobile communication unit  122 , the base station  104  tracks the range and position of the mobile communication unit  122 . In the illustrated example, the electronic control unit  106  determines that the mobile communication unit  122  is on the right hand side of the vehicle  102 . Once the base station  104  determines that the mobile communication unit  122  is within the authorization zone  138 , the electronic control unit  106  automatically generates a door unlock signal to unlock both doors  142 ,  144  on the right hand side of the vehicle  102 . The door unlock signal is transmitted via the CAN bus  120 , and the front right door  142  and the rear right door  144  are both unlocked when the mobile communication unit  122  enters the authorization zone  138 . As the doors  142 ,  144  are unlocked before the user operates the respective door handle, in normal operating conditions it is envisaged that there would be no perceptible delay when the user operates the door handle. 
     In this mode, when the user operates the door handle on either the front right door  142  or the rear right door  144 , either a single-point entry (SPE) or a multiple-point entry (MPE) can be initiated. In single-point entry mode, when the drivers door is the only opened door and the key fob is taken into the vehicle, the rear door on the approached side will be re-locked. For the avoidance of doubt, the driver&#39;s door does not have to be closed to effect the locking of the rear door. If ANY door other than driver&#39;s door is opened, then all doors will be unlocked and remain so. The action of locking the rear door on the driver&#39;s side is caused by the key fob being detected inside the vehicle and thus no longer seen in the authorisation zone on the outside of the vehicle. In a multiple-point entry, the electronic control unit  106  generates control signals to unlock all of the other doors in the vehicle  102  when the door handle of either the front right door  142  or the rear right door  144  is operated. It will be appreciated that the front left door  146  and the rear left door  148  will be unlocked if base station  104  determines that the mobile communication unit  122  enters the authorization zone  138  on the left hand side of the vehicle  102 . Only when the door handle of one of the unlocked doors  142 - 148  is operated is an indication provided that the doors have been unlocked, for example by flashing the side repeaters and/or extending the door mirrors. If none of the door handles are operated, however, no indication is provided that one or more of the doors  142 - 148  have been unlocked. 
     The electronic control unit  106  may be configured to operate the vehicle communication system  100  according to a second operating mode as illustrated in  FIG. 4  to accommodate a walk-past scenario. In this walk-past scenario, the user enters and exits the authorization zone  138  but does not operate a door handle. As in the first mode described above, the base station  104  authenticates the mobile communication unit  122  as it approaches the vehicle  102 . In this case, the base station  104  tracks the position of the mobile communication unit  122  and determines that the user is approaching from the rear of the vehicle  102  on the right hand side. As described above in regard to the first mode of operation, when the vehicle communication system  100  detects that the mobile communication unit  122  has entered the authorization zone  138 , as it has in this walk-past scenario, a door unlock signal is transmitted to unlock the front right door  142  and the rear right door  144 . 
     In this scenario, however, the user does not operate the door handle on either of the doors  142 ,  144  and, instead, walks past the vehicle  102 . Since the vehicle communication system  100  is tracking the position of the mobile communication unit  122 , the vehicle communication system  100  is able to determine when the mobile communication unit  122  leaves the authorization zone  138 . Accordingly, upon the departure of the mobile communication unit  122  from the authorization zone  138 , and lacking the receipt of any indication that a door handle has been operated, the base station  104  transmits a door lock signal to lock the front right door  142  and the rear right hand door  144  or otherwise facilitates the re-locking of those doors. In one embodiment, the vehicle  102  does not provide a visual indication when the doors  142 ,  144  are unlocked or subsequently locked. 
     The electronic control unit  106  may be configured to operate the vehicle communication system  100  according to a third operating mode as illustrated in  FIG. 5  to facilitate the automatic locking of the doors  142 - 148  when the user walks away from the vehicle  102 . In this scenario, the user exits the vehicle  102  carrying the mobile communication unit  122  and closes the vehicle doors  142 - 148 . In the illustrated example, the user exits the vehicle  102  through the front right door  142  and then closes it. The user then walks away from the vehicle  102  carrying the mobile communication unit  122 . 
     As the mobile communication unit  122  is carried away from the vehicle  102 , the vehicle communication system  100  tracks the position of the mobile communication unit  122  and compares that position to the definition of the authorization zone  138 . If and when the vehicle communication system  100  determines that the mobile communication unit  122  has left the authorization zone  138 , the vehicle communication system  100  transmits a door lock signal to lock the doors  142 - 148 . The vehicle  102  is thereby secured automatically without the user activating the mobile communication unit  122  or taking any action other than walking away from the vehicle  102 . A security protocol to comply with industry standards, for example those specified by Thatcham®, would typically be undertaken for the automatic locking of the doors  142 - 148 . Under normal operating conditions, the automatic locking of the vehicle  102  does not double-lock the vehicle  102 . Rather, the vehicle  102  would only be double-locked if the user specifically selected this locking mode, for example via a control panel in the vehicle  102 . 
     The electronic control unit  106  may be further configured to operate the vehicle communication system  100  according to a fourth operating mode as illustrated in  FIG. 6  to accommodate a mis-lock scenario. This mode is similar to the third operating mode described above insofar as the user exits the vehicle  102  through the front right door  142  and closes the door  142  before walking away from the vehicle  102 . In connection with this fourth operating mode, the vehicle communication system  100  again determines if and when the mobile communication unit  122  has departed the authorization zone  138 . As illustrated in  FIG. 6 , however, the rear left door  148  is ajar, and the electronic control unit  106  determines that the door  148  cannot be locked (a so-called mis-lock). 
     To avoid the user leaving the vehicle  102  in an unsecure state (as may otherwise occur if the operator had not noticed that the rear left door  148  was ajar) the electronic control unit  106  transmits an alert signal to the CAN bus  120  and a notification is provided to the user. For example, the CAN bus  120  may illuminate the side repeaters and/or provide an audible warning to notify the user that the doors  142 - 148  have not all been locked. When the rear left door  148  is closed, the vehicle communication system  100  will lock the door  148  to secure the vehicle  102 . 
     In conjunction with the above-described modes of operation, the electronic control unit  106  may be configured to operate the vehicle communication system  100  according to a fifth operating mode, facilitating active communication among components of the vehicle communication system  100  while also decreasing the likelihood of facilitating performance of a vehicle function in accordance with an inadvertent or unintentional command. In order to identify and avoid unintended and unnecessary actuation of vehicle systems, it may be advantageous for the electronic control unit  106  to be able to evaluate whether a command received from the mobile communication unit  122  is to be considered reliable, and therefore acted upon. 
     In many cases, the reliability of a command may be evaluated based on position or movement information associated with the mobile communication unit  122 . In other cases, it is acknowledged that reliability may not be ascertained, and an assessment may nonetheless be made regarding the gravity of harm that may ensue if an inadvertent command were to be carried out. Where an error might be easily detected and remedial action easily accomplished with little chance for negative consequences, the requested action might be performed with a lesser degree of scrituny. Where the gravity of harm is more severe or the likelihood of detection less sure or the production of an acceptable remedy more difficult or costly, a greater degree of scrutiny might be required before performing the requested action. 
     Thus, in one such embodiment, a vehicle communication system  100  for facilitating control over a function of a vehicle  102  comprises a base station  104  that is configured to determine a position of the mobile communication unit  122  relative to the vehicle  102  whenever a user initiated interaction with the vehicle  102  occurs. The position may be stored in the memory for subsequent retrieval and processing. The base station  104  is configured to evaluate whether the position information satisfies predetermined criteria associated with the type of command that is received. For example, when a user initiates interaction with the vehicle  102  including a request to perform a function such as opening a window of the vehicle  102 , the base station  104  is configured to receive the request from the mobile communication unit  122 , to determine a position of the mobile communication unit  122  relative to the vehicle  102  and to evaluate whether the position information satisfies predetermined criteria for requests to open a window or another aperture of the vehicle  102  (e.g., to compare the position of the mobile communication unit  122  relative to the vehicle  102  to the corresponding criteria). 
     In one embodiment, the predetermined criteria associated with a request to open a window or other aperture requires that such commands be performed only when the mobile communication unit  122  is within a range of 25 meters from the vehicle  102 . Alternatively, the criterion may call for the function to be performed only when the mobile communication unit  122  is within five or ten meters. If the position of the mobile communication unit  122  relative to the vehicle  102  satisfies the appropriate criteria, then the base station  104  facilitates performance of the requested vehicle function. In one embodiment, the base station  104  is configured to facilitate performance of the first vehicle function only if the position of the mobile communication unit  122  satisfies the first criteria. 
     A criterion associated with a request for performance of a particular function may include that the position of the mobile communication unit  122  be less than a predetermined distance from the vehicle  102 . Alternatively, a criterion associated with a request for performance of a particular function may include that the position of the mobile communication unit  122  be greater than a predetermined distance from the vehicle  102 . 
     In one embodiment, the base station  104  is configured to receive a plurality of requests (e.g., two requests, three requests, four requests, or even ten or more requests) from the mobile communication unit  122 , each request seeking performance of a unique vehicle function. For example, requests may relate to locking or unlocking an aperture of the vehicle  102 , starting or stopping an engine of the vehicle  102 , opening or closing an aperture of the vehicle  102 , controlling various aspects of an environmental control system (e.g., a heater, blower, defroster, air conditioner), controlling various aspects of an infotainment system (e.g., volume, input source, track, channel, etc.), controlling a vehicle lighting system (e.g., headlamps, fog lamps, interior lighting, puddle lamps), or retrieving information from the vehicle  102  (e.g., a status check). 
     User controls on the mobile communication unit  122  may be embodied as pushbuttons, touch-screens, switches, dials, knobs, levers, or other interfaces known in the art. Each particular request may be associated with a unique criterion that must be satisfied before the request is performed. Alternatively, requests may be classified into a plurality of categories, each having one or more prerequisite criteria that must be satisfied. As such, one set of positions for the mobile communication unit  122  may be acceptable for a first set of requests, while a second, different set of positions for the mobile communication unit  122  may be required for a second set of requests, and a yet another, third set of positions for the mobile communication unit  122  may be required for a third set of requests. 
     Thus, the base station  104  may be configured to facilitate performance of a first vehicle function only if the position of the mobile communication unit  122  satisfies a first criteria, while also being configured to facilitate performance of a second vehicle function only if the position of the mobile communication unit  122  satisfies a second criteria, and while further being configured to facilitate performance of a third vehicle function only if the position of the mobile communication unit  122  satisfies a third criteria. To accommodate differing risks and consequences and remedies associated inadvertent commands or differing classes, the position criteria may differ from one requested function to the next. 
     Similarly to the systems described immediately above, a method for facilitating control over a function of a vehicle  102  may include the steps of providing a base station  104  positioned in the vehicle  102  and a mobile communication unit  122 , wherein the base station  104  comprises a first transmitter for transmitting signals and a first receiver for receiving a signal from the mobile communication unit  122  in response to said transmitted signal. The method includes receiving a first request from the mobile communication unit  122  seeking performance of a vehicle function. Upon receiving the request, the base station  104  determines a position of the mobile communication unit  122  relative to the vehicle  102  and compares the position against a predetermined criteria associated with the requested function. If the position of the mobile communication unit  122  relative to the vehicle  102  satisfies the relevant criterion, the base station  104  facilitates fulfilment of the request and performance of the requested function. As described above, multiple requests may be accommodated, each requiring satisfaction of a unique criterion or set of criteria. 
     As described above, the base station  104  may be configured to determine positions of the mobile communication unit  122  relative to the vehicle  102  based on a time of flight methodology. It should be appreciated, however, that other means for determining a position of the mobile communication unit  122  may be equally applicable. 
     The vehicle communication system  100  can optionally also provide keyless engine starting for the vehicle  102 . By using the ranging data from the transceivers  110 ,  112 ,  114 , the electronic control unit  106  can determine when the mobile communication unit  122  is inside the vehicle  102 . A control signal can be transmitted to the engine control unit, via the CAN bus  120 , to permit keyless engine starting when a Start button is pressed. 
     The vehicle communication system  100  according to the present invention can be further refined. In particular, the electronic control unit  106  can be configured to transmit a status signal to the mobile communication unit  122 . For example, if the base station  104  detects a mis-lock scenario, the status signal may instruct the mobile communication unit  122  to generate a first user alert. Equally, the status signal may instruct the mobile communication unit  122  to generate a second user alert (which is different from the first user alert) when the vehicle  102  has been locked. The first and/or the second user alert could be provided instead of, or in addition to, any notification provided by the vehicle  102 . The mobile communication unit  122  could comprise an audio, optical or haptic output for indicating the vehicle status. For example, the mobile communication unit  122  could comprise one or more of the following: LED(s), a text screen or a vibrating mechanism. 
     The mobile communication unit  122  is also provided with one or more buttons to allow a user to trigger locking/unlocking of the vehicle doors from outside of the authorization zone  138 . 
     The ultra-wideband (UWB) transceivers  110 ,  112 ,  114 ,  124  described herein are compliant with IEEE802.15.4a protocol. 
     The vehicle communication system  100  can monitor time of flight (ToF) communications between the base station  104  and the mobile communication unit  122  to provide improved security, for example to protect against a relay-station security attack. 
     A door unlock override switch can be provided to unlock the doors  142 - 148  in the event of an emergency. 
     The skilled person will understand that various changes and modifications can be made to the vehicle communication system  100  described herein without departing from the spirit and scope of the present invention. For example, a welcome lights function could be supported by illuminating an interior and/or exterior vehicle light when the mobile communication unit  122  enters the authorization zone  138 . 
     Although the vehicle communication system  100  has been described with reference to the mobile communication unit  122  transmitting the polling signal, the system could also operate if the base station  104  transmitted the polling signal. For example, the first transceiver  110  of the base station  104  may transmit a polling signal which, when received by the remote transceiver  124 , initiates communication between the mobile communication unit  122  and the base station  104 . In one embodiment, upon receipt of the polling signal, the mobile communication unit responds by transmitting a response signal. The response signal is received by the first transceiver  110  and the electronic control unit  106  validates the response signal. 
     The mobile communication unit  122  includes a motion sensor, such as a gyroscope or an accelerometer, to detect movements of the mobile communication unit  122 . Signals based on the detected movements may then be transmitted to the base station  104  for use in deciding whether, when and how to facilitate control over functions of the vehicle  102 . For example, if the base station  104  determines that the mobile communication unit  122  has been stationary for a predetermined period of time, the base station  104  may cause the mobile communication unit  122  to be disabled or to enter a sleep mode. In addition, the base station  104  could transmit a disable signal to deactivate the transceivers  110 ,  112 ,  114 ,  124 . Alternatively, the transceivers  110 ,  112 ,  114 ,  124  could be disabled automatically if they do not receive an authorization signal for a predetermined period of time. The mobile communication unit  122  could be awakened by an activation signal from the motion sensor when it detects movement. 
     Moreover, it will be appreciated that it is not necessary for a vehicle communication system  100  according to the present invention to provide all of the operating modes described herein. Rather, one or more of the operating modes could be embodied in a vehicle communication system  100  in accordance with the present invention. 
     It will be appreciated that various changes and modifications can be made to the present invention without departing from the present invention. Further aspects of the present invention will be described with reference to the following numbered paragraphs. 
     1. A vehicle communication system ( 100 ) for facilitating control over a function of a vehicle ( 102 ), the vehicle communication system ( 100 ) comprising: a base station ( 104 ) positioned in the vehicle ( 102 ); and a mobile communication unit ( 122 ); the base station ( 104 ) comprising a first transmitter for transmitting a signal to the mobile communication unit and a first receiver for receiving a signal from the mobile communication unit ( 122 ); the base station ( 104 ) configured to: receive a first request from the mobile communication unit ( 122 ), wherein the first request seeks performance of a first vehicle function; determine a position of the mobile communication unit ( 122 ) relative to the vehicle ( 102 ); compare the position of the mobile communication unit ( 122 ) relative to the vehicle ( 102 ) to a first criteria; and facilitate performance of the first vehicle function if the position of the mobile communication unit ( 122 ) relative to the vehicle ( 102 ) satisfies the first criteria. 
     2. A vehicle communication system ( 100 ) as described in paragraph 1, wherein the base station ( 104 ) is configured to determine the position of the mobile communication unit ( 122 ) relative to the vehicle ( 102 ) based on a time of flight method. 
     3. A vehicle communication system ( 100 ) as described in paragraph 1, wherein the base station ( 104 ) is configured to facilitate performance of the first vehicle function only if the position of the mobile communication unit ( 122 ) satisfies the first criteria. 
     4. A vehicle communication system ( 100 ) as described in paragraph 1, wherein the first criteria requires that the position be less than a first distance from the vehicle ( 102 ). 
     5. A vehicle communication system ( 100 ) as described in paragraph 1, wherein the first criteria requires that the position be greater than a first distance from the vehicle ( 102 ). 
     6. A vehicle communication system ( 100 ) as described in paragraph 1, wherein the base station ( 104 ) is configured to: receive a second request from the mobile communication unit ( 122 ), wherein the second request seeks performance of a second vehicle function; compare the position of the mobile communication unit ( 122 ) relative to the vehicle ( 102 ) to a second criteria; and facilitate performance of the second vehicle function if the position of the mobile communication unit ( 122 ) relative to the vehicle ( 102 ) satisfies the second criteria 
     7. A vehicle communication system ( 100 ) as described in paragraph 6, wherein the base station ( 104 ) is configured to facilitate performance of the first vehicle function only if the position of the mobile communication unit ( 122 ) satisfies the first criteria, and wherein and the base station ( 104 ) is configured to facilitate performance of the second vehicle function only if the position of the mobile communication unit ( 122 ) satisfies the second criteria. 
     8. A vehicle communication system ( 100 ) as described in paragraph 6, wherein the first criteria requires that the position be within a first distance from the vehicle ( 102 ), and wherein the second criteria requires that the position be within a second distance from the vehicle ( 102 ). 
     9. A vehicle communication system ( 100 ) as described in paragraph 8, wherein the first distance is greater than the second distance. 
     10. A vehicle communication system ( 100 ) as described in paragraph 6, wherein the base station ( 104 ) is configured to: receive a third request from the mobile communication unit ( 122 ), wherein the third request seeks performance of a third vehicle function; compare the position of the mobile communication unit ( 122 ) relative to the vehicle ( 102 ) to a third criteria; and facilitate performance of the third vehicle function if the position of the mobile communication unit ( 122 ) relative to the vehicle ( 102 ) satisfies the third criteria. 
     11. A vehicle communication system ( 100 ) as described in paragraph 10, wherein the base station ( 104 ) is configured to facilitate performance of the first vehicle function only if the position of the mobile communication unit ( 122 ) satisfies the first criteria, and wherein and the base station ( 104 ) is configured to facilitate performance of the second vehicle function only if the position of the mobile communication unit ( 122 ) satisfies the second criteria, and wherein and the base station ( 104 ) is configured to facilitate performance of the third vehicle function only if the position of the mobile communication unit ( 122 ) satisfies the third criteria. 
     12. A vehicle communication system ( 100 ) as described in paragraph 10, wherein the first criteria requires that the position be within a first distance from the vehicle ( 102 ), wherein the second criteria requires that the position be within a second distance from the vehicle ( 102 ), and wherein the third criteria requires that the position be within a third distance from the vehicle ( 102 ). 
     13. A vehicle communication system ( 100 ) as described in paragraph 12, wherein the first distance is greater than the second distance, and wherein the second distance is greater than the third distance. 
     14. A vehicle communication system ( 100 ) as described in paragraph 1, wherein the first vehicle function comprises locking an aperture of the vehicle ( 102 ). 
     15. A vehicle communication system ( 100 ) as described in paragraph 6, wherein the second vehicle function comprises starting an engine of the vehicle ( 102 ). 
     16. A vehicle communication system ( 100 ) as described in paragraph 10, wherein the third vehicle function comprises opening an aperture of the vehicle ( 102 ). 
     17. A vehicle communication system ( 100 ) as described in paragraph 10, wherein the third vehicle function comprises closing an aperture of the vehicle ( 102 ). 
     18. A method for facilitating control over a function of a vehicle ( 102 ) comprising: providing a base station ( 104 ) positioned in the vehicle ( 102 ) and a mobile communication unit ( 122 ), the base station ( 104 ) comprising a first transmitter for transmitting a signal and a first receiver for receiving a signal from the mobile communication unit ( 122 ); receiving a first request from the mobile communication unit ( 122 ), wherein the first request seeks performance of a first vehicle function; determining a position of the mobile communication unit ( 122 ) relative to the vehicle ( 102 ); comparing the position of the mobile communication unit ( 122 ) relative to the vehicle ( 102 ) to a predetermined first criteria; and facilitating performance of the first request if the position of the mobile communication unit ( 122 ) relative to the vehicle ( 102 ) satisfies a first criteria. 
     19. A method for facilitating control over a function of a vehicle ( 102 ) as described in paragraph 18, further comprising: receiving a second request from the mobile communication unit ( 122 ), wherein the second request seeks performance of a second vehicle function; comparing the position of the mobile communication unit ( 122 ) relative to the vehicle ( 102 ) to a second criteria; and facilitating performance of the second vehicle function if the position of the mobile communication unit ( 122 ) relative to the vehicle ( 102 ) satisfies the second criteria. 
     20. A method for facilitating control over a function of a vehicle ( 102 ) as described in paragraph 19, further comprising: receiving a third request from the mobile communication unit ( 122 ), wherein the third request seeks performance of a third vehicle function; comparing the position of the mobile communication unit ( 122 ) relative to the vehicle ( 102 ) to a third criteria; and facilitating performance of the third vehicle function if the position of the mobile communication unit ( 122 ) relative to the vehicle ( 102 ) satisfies the third criteria. 
     21. A vehicle having a vehicle communication system, or being adapted to perform a method as described in paragraph 1 or 18.