Method and system for access control using short-range wireless communication

Abstract

To provide a method and a system for access control improved for access control regarding many users, safety, and response time.SOLUTION: In an access control system 100 that is connected to mobile devices with use of radio frequency communications, a control unit 110 sends a motion status request to connected mobile devices 120-122 and a non-connected device 123 in response to a generated event. Each mobile device estimates a probability that a user of the connected mobile device is a user who gives a request on the basis of received signal intensity data and human sensor data collected from a human sensor included in the mobile device, and sends an indication of the probability as a reply to the control unit. The control unit determines whether or not to carry out an action based on the indication of the probability that the connected mobile device is associated with the event.SELECTED DRAWING: Figure 1a

Description

[Technical field]

[0001] The embodiments herein relate to a method and system for access control using short-range wireless communication. In particular, the present invention relates to determining whether to arrange to perform an action in response to a request in an access control system comprising an access control unit and one or more mobile devices. [Background technology]

[0002] A system using short-range wireless communication for access control usually comprises a control unit and a mobile device. The short-range wireless communication between the mobile device and the control unit may be performed, for example, via Bluetooth, Bluetooth Low Energy (BLE), Zigbee, Wifi, Radio Frequency Identification (RFID), etc. Current solutions for access control, for example at door stations, using Bluetooth wireless communication are one-to-one solutions in which a secure Bluetooth connection between the control unit and the mobile device is set up after the mobile device user presses a button on the door station or the mobile device. The connection time is then up to 10 seconds, which makes the opening process much longer than opening a door with an RFID badge and reader.

[0003] There are other products that use Bluetooth® access control solutions with one-to-one secure connection, for example, the mobile device automatically connects when it reaches the Hello message sent by the door station. As an additional password to the door open command, the user moves the mobile device in a predefined pattern that is sensed by a motion sensor in the mobile device. If the movement pattern is correct, the mobile device sends an OK to the door station that opens the door.

[0004] Patent document 1 discloses a method for controlling access in a system having a mobile device associated with a user and an access control device. The mobile device and the access control device are configured to wirelessly communicate with each other. The method compares the received signal strength over time with a previously determined reference signal strength profile. By determining the signal strengths over time and comparing them with the determined reference signal strength profile, it is possible to distinguish between a first situation in which a user is approaching an office door with the intention of entering an office space and a second situation in which a user is approaching an office door with the intention of passing the office door in a hallway. The method also compares motion sensor data with a reference value. The movement pattern of the mobile device is used to obtain more accurate timing for controlling the access control device to avoid or at least reduce undesirable delays or wait times for the user.

[0005] US Patent No. 5,999,333 discloses a wireless access control system including a remote access device and an electronic lock. The electronic lock communicates with the remote access device. The electronic lock controls the ability to lock and unlock a door in which the electronic lock is located. The electronic lock determines when the remote access device is within a predetermined distance from the lock so that the lock can be unlocked. In one embodiment, to determine that the remote access device is actually in a position to access the lock, the wireless access control system determines the radio signal strength of an access request from the remote access device. A controller of the remote access device determines whether the radio signal strength is greater than a predetermined value. If so, a signal is sent from the wireless access control system to the remote access device. The remote access device determines the radio signal strength of the signal from the wireless access control system, and permission to control the lock is only given if the remote access device determines that the remote signal strength of the signal from the wireless access system is above a predetermined threshold.

[0006] However, there are problems associated with multiple users of an access control system: for example, there may be more mobile devices trying to connect to a control unit than the control unit can handle.

[0007] Furthermore, current solutions for access control have limited security features or are relatively slow to respond. For example, some solutions use a received signal strength indicator (RSSI) threshold to determine proximity to an access unit and then grant access to anyone in close proximity. Some solutions omit RSSI monitoring altogether and simply grant access to anyone who presses a button on an access application (app) in a mobile device. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] European Patent Application Publication No. 3477600 A1 [Patent Document 2] International Publication No. 2015 / 023737 Brochure Summary of the Invention [Problem to be solved by the invention]

[0009] In view of the above, it is an object of the embodiments herein to provide improved methods and systems for access control for multiple users, security, and response time.

[0010] According to an aspect of an embodiment herein, the object is achieved by a method performed in an access control system. The access control system may be a system for controlling access to a physical or logical area or resource. The method is for determining whether to arrange to perform an action in response to an event occurring in the access control system. The access control system comprises a control unit connected to one or more mobile devices using radio frequency signal communication. Respective access applications are installed on the one or more mobile devices. The access applications communicate with the control unit and may perform or arrange for the mobile devices to perform an action in response to communication with the control unit. For example, the access applications may perform or arrange for the mobile devices to perform some of the following actions:

[0011] An event represents a request for a control unit to arrange for an action to be performed. The control unit controls access to physical or logical areas or resources depending on the event that has occurred.

[0012] In some embodiments, the action performed is to provide access to a physical resource, such as opening any type of lock, e.g., locking a door, lid, window, etc. In some other embodiments, the action is to provide access to a logical resource, such as a database, the contents of a logical area, or a protected device.

[0013] A request for an action to be performed may be given by a user of a mobile device located near the control unit. The request may be given, for example, by pressing a button or touching a touch screen on or at the control unit, by activating an IR detector on or located at the control unit, or by causing a noise to be detected by a microphone on or at the control unit. The request may be given anonymously. The request may be a command to gain access to a physical area, the contents of a logical area, a protected device, or a protected resource controlled by the control unit.

[0014] The request may be given by a user authorized to cause an action, or by someone who is not: having a mobile phone connected to the control unit may mean, in itself, that the user is authorized to cause an action, or having a mobile phone connected may be only a first authorization level that leads to a check of a second authorization level (whether or not allowed to cause an action) being initiated.

[0015] The user of the mobile device may be a person or object carrying the device. The user of the mobile device may have access rights associated with resources controlled by the control unit. The user of the mobile device may be located in physical proximity to the mobile unit when the method is performed.

[0016] The access control system further comprises a radio frequency transceiver. The method includes transmitting, by the radio frequency transceiver, a radio frequency signal to be used for measurements of received signal strength by one or more connected mobile devices.

[0017] The control unit transmits an operation status request to a connected mobile device among the one or more connected mobile devices in response to an event that has occurred.

[0018] The method further comprises determining an indication of a probability that the connected mobile device is associated with the event. Determining the indication of the probability is based on received signal strength data and motion sensor data of the connected mobile device. The received signal strength data is measured by the connected mobile device for a radio frequency signal transmitted during a first predetermined period before a motion state request from the control unit is received. The received signal strength may be an indication of a signal energy level or a signal power level received at a receiver of the mobile device. An example of a measure of received signal strength used may be a received signal strength indicator (RSSI), or a received channel power indicator (RCPI).

[0019] The motion sensor data is collected from a motion sensor included in the connected mobile device during a second predetermined period before the motion status request from the control unit is received. The motion sensor may be, for example, a sensor that measures linear acceleration in up to three axes, such as an accelerometer, a sensor that measures rotation, such as a gyroscope, a sensor that measures air pressure, such as a barometer, or a sensor that measures orientation, such as a compass.

[0020] The control unit further determines whether to arrange for the connected mobile device to perform an action based on an indication of a probability associated with the event.

[0021] According to a further aspect of an embodiment herein, the object is achieved by an access control system configured to perform the above method. The access control system comprises a control unit and one or more mobile devices. The mobile devices may be any one of a mobile phone, a tablet, a laptop, a key fob, a smart watch, or a smart bracelet. The control unit may be any unit that controls access to a physical area, a logical area, a protected device, or a protected resource.

[0022] In other words, according to embodiments herein, one or more mobile devices are connected to the control unit. One or more mobile devices may be automatically connected to the control unit, for example, when they are within reach of the control unit. In some embodiments herein, when the mobile devices are connected to the control unit, a secure communication channel is established between the mobile devices and the control unit. Furthermore, the connection of the mobile devices can mean that the mobile devices are pre-authorized to cause actions, i.e., the user of the mobile devices is authorized to cause actions and is an authorized user of the services by the control unit. With this authentication, the control unit is arranged to execute the request requested by the mobile user. However, the automatic connection merely sets up a communication channel, while all security requirements, authorizations and encryptions are handled later when required.

[0023] A request for an action to be performed, such as a door open command, may be given, for example, by pressing a button on or at the control unit or by touching a touch screen. Furthermore, the request may be given by a user authorized to cause the action, or by someone not authorized to cause the action, for example, a user of a mobile device that is not authenticated or pre-authorized, not paired or bonded, or by a user without a mobile device, or a user with a mobile device but without an access application. The request may also be given by a user of a mobile device that is paired but not connected, which may occur when a maximum number of connections to the control unit is reached. When the control unit registers an event or gets an indication of an event that is the result of a request given by someone, a verification process is performed to determine whether one of the connected mobile devices is associated with the event, in other words whether it was a user of one of the connected mobile devices that gave the corresponding request, and to determine whether the requested action, e.g., opening the door, should be arranged. The control unit starts this verification process by sending a motion state request to one or more connected mobile devices. A corrected estimate may be calculated for each of the one or more connected mobile devices based on the received signal strength and the motion sensor data to estimate the probability that the connected mobile device is associated with the event, in other words, the probability that the user of the connected mobile device is the user who generated the request. An action is then determined based on the indication of the probability that the connected mobile device is associated with the event. If the indication of the probability of the connected mobile device indicates that it is the user of this connected mobile device who has given the request with the intent to open the door, the action may be to perform the requested action, e.g., to open the door.Also, if the indication of probabilities of all connected devices indicates that none of the users of the connected devices have given the request, the action may be to not perform the requested action, i.e., not to open the door. In addition, the control unit may also decide to release at least one connection between the mobile device and the control unit to allow other paired or coupled mobile devices to connect to the control unit, since the request may be given by a user of a paired but not connected mobile device. By releasing at least one connection, this paired mobile device can connect to the control unit, allowing the user of this mobile device to trigger the action by requesting the action.

[0024] An advantage of the embodiments herein is that the requested activity can be triggered quickly and securely without the requester needing a separate access control device such as an RFID card. Another advantage is that the user of the mobile device does not need to interact with the mobile device, so that the mobile device can remain in the user's pocket. An advantage of automatically connecting each paired mobile device when in range of the control unit is that when the user of the mobile device gives a request, e.g. a door open command, the connection is already set up and there is no delay in opening the door. In other words, since the connected mobile devices are already connected, the control unit can react quickly to the request, e.g. by performing the requested action. For example, if a request is given by a user from a paired mobile device that is already connected to the control unit, e.g. by pressing a button on the mobile device or touching a screen, the request is sent to the control unit and since the control unit knows that the request came from a paired and thereby pre-authorized mobile device, it arranges the requested action, e.g. opening the door, without further analysis. However, if a request is given to the control unit, for example by pressing a button on or at the control unit or by touching a touch screen, the control unit must be able to determine whether the request is given by a user of the connected mobile device, i.e. by a user who has a mobile device connected to the control unit. Several mobile devices may be connected to the control unit at the same time. Some of them may belong to users who have not given a request to the control unit and do not want to access, for example, a door controlled by the control unit. By sending a motion state request and then deciding whether or not the connected mobile device will arrange to perform an action in response to the event based on an indication of the probability associated with the event, the control unit can verify whether the request is given by a user of the connected mobile device with the intention to open the door.In this way, the requested action can be arranged in a secure manner. Furthermore, using the motion data to improve the evaluation of the RSSI data provides additional security, so that the control unit does not decide to perform an action on a user that is not associated with the event, for example a user who has placed their mobile device on a table or in a bag, but is still close to the control unit.

[0025] The embodiments herein monitor the behavior of users of connected mobile devices and arrange access for those who actually have the intent and right to access. The embodiments herein also prevent the control unit from performing a requested action by someone unauthorized, or by an authorized user of a mobile device that is located near a control unit with an active connection but whose user has not requested the action, or by an authorized user of a mobile device that is walking past the door and not approaching the door when a request is given to the control unit by another person.

[0026] The embodiments herein also allow for monitoring many mobile devices at once and prioritizing them, for example, by disconnecting selected connections, such as connections to inactive mobile devices or simply passing mobile devices, so that incoming users can be connected faster.

[0027] Thus, embodiments herein provide improved methods and systems for access control for multiple users, security, and response time.

[0028] Example embodiments will now be described in more detail with reference to the accompanying drawings. [Brief description of the drawings]

[0029] [Figure 1a] 1 is a block diagram illustrating an access control system in which embodiments herein may be implemented. [Figure 1b]1 is a block diagram illustrating a further access control system in which embodiments herein may be implemented. [Diagram 2] 1 is a flow chart illustrating a method performed by a control unit for access control according to embodiments herein. [Diagram 3] 1 is a flow chart illustrating a method performed by a mobile device for access control according to embodiments herein. [Figure 4] 4 is a flow chart illustrating a method performed by a control unit and a mobile device for access control according to embodiments herein. [Figure 5a] 10 is a flow chart illustrating a further method performed by the control unit and the mobile device for access control according to embodiments herein. [Figure 5b] FIG. 2 is a signaling diagram illustrating a method for handling a radio frequency connection between a control unit of an access control system and a mobile device according to embodiments herein. [Figure 6] FIG. 2 is a block diagram illustrating a control unit in which methods according to embodiments herein may be implemented. [Figure 7] 1 is a block diagram illustrating a mobile device in which methods according to embodiments herein may be implemented. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] 1a and 1b are block diagrams illustrating two embodiments of an access control system 100 in which embodiments herein for determining whether to arrange to perform an action in response to an event generated in the access control system may be implemented.

[0031] As shown in both Figures 1a and 1b, the access control system 100 comprises a control unit 110 exemplified as a door station for controlling access to a physical area, such as opening / unlocking or keeping closed and / or locked any type of lock, e.g., lock 111a of a door 111b, lid, window, etc., in response to a generated event.

[0032] However, the control unit 110 may control access to logical resources such as logical areas, databases, protected devices, or protected resources in response to an event. The control unit 110 may, for example, grant or deny access to the contents of a database or logical area, protected devices, or protected resources. To control access to a physical area, the control unit 110 may, for example, be a per-door command receiver connected to an intelligent door station, a simple keypad, a card reader, or a remotely located intelligent access control device. As shown in FIG. 1a, the control unit 110 may comprise a radio frequency transceiver 112 having a wireless short-range communication function for communicating with one or more mobile devices using radio frequency signal communication, as shown in FIG. 1a. The control unit 110 may further comprise a request receiving unit 113, for example, a button to press, a touch screen, an IR detector, or a microphone, as also shown in FIG. 1a. The control unit 110 may further comprise a start-up module that may be arranged to perform a requested operation, and a memory and a processor not shown in either FIG. 1a or FIG. 1b. Additionally, processing and storage means external to the control unit 110 may also be used by the access control system 100. For example, a cloud service or a web server may perform some of the following operations described as being performed by the control unit 110.

[0033] In the embodiment shown in Fig. 1b, the radio frequency transceiver 112 and the request receiving unit 113 are external to the control unit 110 and connected to the control unit 110. Since measurements of the received signal strength of the signal transmitted from the radio frequency transceiver 112 are used to determine whether a mobile device is associated with an event generated by the request receiving unit 113, the radio frequency transceiver 112 and the request receiving unit 113 should in any case be close to each other in order to carry out the embodiments described herein. Close to each other can mean, for example, that the distance between these two units should not be larger than the resolution or the average positioning error of the measurements of the received signal strength. Such an average positioning error can be, for example, of the order of 1-5 meters in state-of-the-art BLE solutions. Furthermore, if the radio frequency transceiver 112 is external to the control unit 110, the radio frequency transceiver 210 is preferably arranged close to the control unit 110.

[0034] The control unit 110 may further be connected, for example wirelessly or by wire, to the door 111b or, as shown in Figures 1a and 1b, to the lock 111a of the door 111b. The control unit 110, the radio frequency transceiver 112 and the request receiving unit 113 may each be located near an object, such as the lock 111a of the door 111b, that is controlled by the access control system 100.

[0035] The access control system 100 further comprises one or more connected mobile devices 120-122 shown in Fig. 1a and Fig. 1b, and / or a respective access application installed on the one or more connected mobile devices 120-122. The respective access application may communicate with the control unit 110 and may execute or arrange for the respective one or more connected mobile devices 120-122 to perform operations in response to communication with the control unit 110. For example, the access application may execute or arrange for the respective one or more connected mobile devices 120-122 to perform some of the following operations: (a) download the data from the respective one or more connected mobile devices 120-122 and / or download the data from the respective one or more connected mobile devices 120-122. (b) download the data from the respective one or more connected mobile devices 120-122 and / or download the data from the respective one or more connected mobile devices 120-122. (c) download the data from the respective one or more connected mobile devices 120-122 and / or download the data from the respective one or more connected mobile devices 120-122. (d) download the data from the respective one or more connected mobile devices 120-122 and / or download the data from the respective one or more connected mobile devices 120-122. (e) download the data from the respective one or more connected mobile devices 120-122 and / or download the data from the respective one or more connected mobile devices 120-122. (f) download the data from the respective one or more connected mobile devices 120-122 and / or download the data from the respective one or more connected mobile devices 120-122. (g) download the data from the respective one or more connected mobile devices 120-122 and / or download the data from the respective one or more connected mobile devices 120-122. (h) download the data from the respective one or more connected mobile devices 120-122 and / or download the data from the respective For example, each access application may arrange for a cloud service or a web server to perform the following operations:

[0036] In addition to the connected mobile devices 120-122, Figures 1a and 1b also show unconnected mobile devices 123 in the vicinity of the access control system 100. Figures 1a and 1b further show respective arrows pointing away from some of the connected mobile devices 120-122 and away from the unconnected mobile devices 123. Each arrow indicates the direction of movement of the respective mobile device 120-123. One of the mobile devices is not associated with an arrow, which means that this mobile device is stationary, i.e., its velocity is zero. Each of the connected mobile devices 120-122 may be, for example, a mobile phone, a laptop, a tablet, a key fob, a smart watch, or a smart bracelet. A user of the mobile device may request access to the physical domain, the content of the logical domain, the protected device, or the protected resource. Each connected mobile device 120-122 may also have wireless short-range communication capabilities and may include a radio frequency transceiver, a memory, and a processor for communicating with the control unit 110 using radio frequency signal communication. Each of the connected mobile devices 120-122 is associated with a user.

[0037] Short-range wireless communication between each mobile device 120-122 and the control unit 110 may be performed, for example, via Bluetooth (registered trademark), BLE, Zigbee, Wifi, RFID, Ultra-Wideband (UWB), FeliCa (registered trademark), ANT+, Z-Wave, or via infrared communication or ultrasonic communication.

[0038] A mobile device, such as a connected mobile device 120-122, may automatically connect to the control unit 110 when it is within reach of the control unit 110. Some examples of when a mobile device is within range of the control unit 110 are when the mobile device detects or receives a Hello message sent by the control unit 110 using Bluetooth®, or when the distance between the respective mobile device and the control unit 110 is less than a threshold distance, e.g., 1 m, which may be measured using location services, a Global Positioning System (GPS), or an indoor location system. Distance measurement may also be achieved by analysis of characteristics of wireless communication, e.g., via time of flight, or some other method combining such analysis with phase difference. Such distance measurement may be performed, for example, using UWB. Motion sensor data of the mobile device may also be used to determine when the respective mobile device automatically connects to the control unit 110. For example, if the first mobile device 120 is stationary, or if its motion sensor data is below a threshold, or if it is moving away from the control unit 110, etc., according to some embodiments, the first mobile device 110 does not automatically connect to the control unit 110.

[0039] In the embodiment of the present specification, several mobile devices may be connected at the same time, which allows for a quicker reaction to event generation. However, the pre-pairing step is optional. One way to solve the connection step is a pairing process, which can be described as a setup configuration to achieve permission to enable automatic connection. This pairing is not necessarily an authorization for any further operation.

[0040] Another way to solve the connection step is to perform the connection authorization every time the mobile device is close enough to the control unit 110, but before the user of the mobile device generates an event by request.

[0041] As described above, once automatically connected to the control unit 110, each connected mobile device 120-122 may be bound or paired to the control unit 110 by a pairing process. When two devices are paired, they may share their addresses, names, and profiles, and typically store them in memory. They may also share a common secret key, which allows them to bind or pair whenever they come together in the future.

[0042] Pairing typically requires an authentication process in which a user must verify the connection between the devices. The flow of the authentication process varies and usually depends on the interfacing capabilities of one device or the other.

[0043] Below is an example of the door station pairing process: · The door station sends an encryption key and an authentication identification (ID) to the mobile device. The user launches the Mobile Access app on their mobile device and enters pairing mode. In pairing mode, the mobile app scans for available door stations to pair with. The user selects the correct door station and enters the pairing PIN code. The pairing PIN must be generated by the door station and provided to the user in some form. Any known pairing method can be applied to the selected RF communication method. Encryption keys and authorization IDs are exchanged after the door station verifies the pairing PIN. It is the mobile device’s authorization ID that contains the access rights to open the door, for example.

[0044] After this pairing process, the mobile device is bound or paired to the door station. When the mobile device reaches the door station, it can begin the following pre-authentication process. Connect to a door station. Establishing a secure communication channel with the door station using the encryption key received during pairing.

[0045] If pairing, i.e. authentication, does not occur prior to automatic connection, it may occur either at the time of connection or at the time of request, e.g., when a button is pressed and the control unit 110 determines who pressed it. This may be, for example, when the control unit 110 makes an authorization call to an access rights database.

[0046] In some embodiments herein, no pairing, authentication or encryption keys are used at all. Instead, the mobile device 120 may connect when it is within range of the control unit 110, and then any security checks are performed following the event.

[0047] It is known that when devices connect with each other, for example in a Bluetooth® piconet, there exists a master-slave relationship between the two devices. One of the devices is the master and the other device is the slave. According to some embodiments herein, the control unit 110 can act as a master, and according to some other embodiments, each mobile device 120-122 can act as a master.

[0048] To demonstrate a method for determining whether to perform an action in response to an event generated in an access control system 100 according to an embodiment of the present specification, an example scenario of access control to a physical area where the radio frequency communication is BLE (Bluetooth Low Energy) is described below in relation to FIG. 1a.

[0049] A control unit 110 in the form of a BLE-enabled door station controlling access to a door 111b, e.g. an office room of a project, is placed in an office environment. In the office environment there are several mobile devices 120-122 in the form of mobile phones with an access app, all of which are paired with the door station 110 and have a valid certificate, e.g. a valid pre-authentication verifying that they are granted access to the office rooms of the project. In the office environment there are also mobile devices with access apps that are not paired with a door station, i.e. do not have a valid certificate and therefore do not have access to the office rooms of the project. The mobile devices 120-122 may be carried by a user or may be placed on a desk or in a bag in the office environment.

[0050] When within range of the control unit 110, a paired mobile device 120 automatically connects to the control unit 110 and a secure communication channel over Bluetooth is established with the control unit 110. A user of the mobile device can request the control unit 110 to perform an action, such as a door open command. The request can be performed by pressing a button or touching a screen included in the access control system 100, such as on the control unit 110 or in the control unit 102, or by any of the other methods described above.

[0051] The request may be generated by a user authorized to cause the action, but may also be generated by someone other than the user, such as, for example, a user of a mobile device that is not authenticated, not authorized, not paired, or not bound, or a user that does not have a mobile device, or a user that has a mobile device but does not have the access app. The request at or on the control unit 110 may also be given by a user of a mobile device that is paired but not connected, which may occur when the maximum number of connections to the control unit 110 is reached. If a user of a mobile device that is not authenticated or not paired, or a user that does not have a mobile device or access app at all, presses a button or touches a screen on the control unit 110, the door should not be opened. If a user of a mobile device that is paired but not yet connected presses a button or touches a screen on the control unit 110 or on the control unit 210, the request should result in the door being opened.

[0052] The problem that arises in this scenario is how the control unit 110 should verify that the user who gave the open door command on the control unit 110 is an authorized user who has a paired mobile device with a valid certificate, and how the control unit 110 should decide whether to open the door or not.

[0053] When the control unit 110 receives an event as a result of a request given by someone at or on the control unit 110, a verification process is required to determine whether it is the user of a connected mobile device or a user of a paired but unconnected mobile device making the request and to decide whether the requested action, e.g., opening a door, should be performed.

[0054] In the following, a method for solving the above problem is described with reference to the flowchart shown in FIG. 2 and with further reference to the access control system shown in FIG. 1a and FIG. 1b. The flowchart in FIG. 2 shows a method for deciding whether to perform an action in response to an event generated in the access control system 100. The problem is solved by deciding whether to arrange to perform an action in response to an event generated in the access control system 100. The event indicates a request for the control unit 110 to arrange to perform an action. The event generated in the access control system 100 may be the result of a request given by a user of a mobile device 120. In some embodiments, the user of the mobile device is a user of one of one or more connected mobile devices 120-122. In other embodiments, the user of the mobile device is a user of a non-connected mobile device 123. Although the method is described below with respect to a connected mobile device 120, the method may be applied to multiple connected mobile devices 120-122 in parallel or in series.

[0055] As mentioned above, the access control system comprises a control unit 110 connected to one or more mobile devices 120-122 using radio frequency signal communication.

[0056] One or more of the following operations presented in FIG. 2 may be performed in the following example order. In other examples, the order may differ from that described below. The method may include the following operations.

[0057] Operation 201 The control unit 110 arranges to transmit radio frequency signals that are used for measuring received signal strength by one or more connected mobile devices 120-122. For example, in some embodiments, the control unit 110 controls the radio frequency transceiver 112 to transmit radio frequency signals that are used for measuring received signal strength by one or more connected mobile devices 120-122. In some embodiments, the unit that actually transmits the RF signals, such as the radio frequency transceiver 112, is not necessarily included in the control unit 110 as shown in FIG. 1a, but is connected to, controlled by and optionally located close to the control unit 110 as shown in FIG. 1b. As mentioned above, since the determination of the probability that the connected mobile device 120 is associated with the event is based on the RF signals transmitted from the transceiver 112, it may be important that the radio frequency transceiver 112 is located close to the request receiving unit 113.

[0058] These RF signals are used to determine an indication of the probability that a particular connected mobile device 120 of the one or more connected mobile devices 120-122 is associated with an event generated in operation 202 below, as described in operation 204 below.

[0059] Operation 202 Then, at some point, someone generates an event that indicates a request to arrange for the control unit 110 to perform an action. For example, a user of a connected mobile device 120 generates an indication of a request to open the door 111b.

[0060] As mentioned above, in some embodiments, the request for the control unit 110 to arrange to perform an action includes a request to grant access to a physical domain, a logical domain, a protection device 111a, 111b, or a protected resource. In these embodiments, determining whether to arrange to perform an action in response to the generated event includes determining whether to grant access to the physical domain, the logical domain, the protection device 111a, 111b, or a protected resource.

[0061] operation 203 The control unit 110 initiates the verification process upon generation of the event by sending a respective motion status request to a respective one of the one or more connected mobile devices 120-122. The control unit 110 may send the respective motion status request to each of the connected mobile devices 120-122 or to selected ones of the connected mobile devices 120-122, but not to at least one of them.

[0062] Before sending the motion status request, the control unit 110 may obtain an indication of the event or may register the event, which may be the case if the event is generated in a separate unit, such as the request receiving unit 113.

[0063] The control unit 110 transmits an operation status request to the connected mobile device 120 among the one or more connected mobile devices 120-122 in response to the generated event.

[0064] The motion status request serves as a trigger for the connected mobile device 120 to compile received signal strength data and motion sensor data to be used to determine an indication of the probability that the connected mobile device 120 is associated with the event in a subsequent operation 204. In some embodiments, the motion status request requests the connected mobile device 120 to respond with an indication of the probability that the connected mobile device 120 is associated with the event.

[0065] operation 204 Both the control unit 110 and the connected mobile device 120 may determine an indication of the probability that the connected mobile device 120 will be associated with the event.

[0066] As described above, determining the indication of probability is based on received signal strength data, such as RSSI, and motion sensor data, such as accelerometer data or angular velocity data, of the connected mobile device 120. The received signal strength data is measured by the connected mobile device 120 for radio frequency signals transmitted during a first predetermined period before the motion state request is received from the control unit 110. In other words, the received signal strength data is derived by the mobile device 120 from measurements of the transmitted radio frequency signals.

[0067] The motion sensor data is collected from the motion sensor included in the connected mobile device 120 during a second predetermined period of time before the motion status request is received from the control unit 110. The second predetermined period of time may be different from the first predetermined period of time. It should be noted that, although not shown in Figures 1a and 1b, each connected mobile device 120-122 may include a respective motion sensor.

[0068] By determining an indication of the probability based on both received signal strength data and motion sensor data, increased accuracy of the determination is achieved, as compared to, for example, determining the probability based only on received signal strength data. For example, the motion sensor data may be used to correct an estimate of the probability based on the received signal strength data, as described in more detail below.

[0069] In some embodiments, determining an indication of the probability comprises calculating an estimate indicative of a probability that the connected mobile device 120 is associated with the event based on the received signal strength data. The estimate may include, for example, an estimated time to reach the request receiving unit 113 or the radio frequency transceiver 112. As mentioned above, if the radio frequency transceiver 112 is external to the control unit 110, the radio frequency transceiver 220 is preferably located near the control unit 110.

[0070] In other embodiments, the estimate includes an estimated distance to reach the control unit 110, possibly in combination with an estimated speed, such as an estimated constant speed. In yet other embodiments, the estimate includes an estimated increase in signal strength reaching the control unit 110.

[0071] Determining the indication of the probability may further comprise calculating a corrective motion factor based on the motion sensor data and adjusting the estimate with the corrective motion factor to obtain a corrected estimate indicative of the probability.

[0072] In some embodiments, the corrected estimate corresponds to a corrected estimated time to reach the radio frequency transceiver 112. Calculating the corrected estimated time to reach the radio frequency transceiver 112 then comprises calculating an estimated time for the mobile device 120 to reach the control unit 110 based on the received signal strength data, calculating a corrected motion factor based on the motion sensor data, and adjusting the estimated time by the motion factor to obtain the corrected estimated time. For example, the estimated time may be divided by the motion factor, as described in more detail below. In other embodiments, the estimated time may be multiplied by the motion factor.

[0073] When the corrected estimate is calculated, determining an indication of the probability may comprise comparing the corrected estimate, indicative of the probability that the connected mobile device 120 is associated with the event, to a predefined threshold value corresponding to a predefined probability that the connected mobile device 120 is associated with the event. For example, the corrected estimate may be a corrected estimated time to reach the control unit reaching 5 seconds. The corrected estimated time may be compared to a threshold value of 10 seconds. A time below the threshold time is associated with a high probability, which may be indicated, for example, with "yes" or a 95% probability or the like.

[0074] In some embodiments, determining an indication of the probability based on the received signal strength data and the motion sensor data comprises calculating, by the connected mobile device 120, a corrected estimate based on the received signal strength data and the motion sensor data. The method may then further comprise sending, by the connected mobile device 120, the indication of the probability and / or the corrected estimate to the control unit 110 in response to a motion status request. Responses to motion status requests are further described below in connection with operation 205.

[0075] When the control unit 110 transmits a motion status request to a plurality of connected mobile devices 120-122 of the one or more connected mobile devices 120-122, determining an indication of a probability may comprise determining a respective indication of a probability that a respective one of the plurality of connected mobile devices 120-122 is associated with the event. In such an embodiment, determining whether to arrange to perform an action described below in operation 206 comprises determining whether to arrange to perform an action based on the respective indication of the probability. For example, the control unit 110 may determine to arrange to perform an action in response to a first positive response to the plurality of motion status requests. The method may then stop processing further responses, or the method may continue to process further responses.

[0076] Details of operation 204 are described below. Upon receiving the motion status request, a corrected estimate may be calculated for each of one or more connected mobile devices 120-122 based on the received signal strength data and the motion sensor data to estimate the probability that the user of the connected mobile device is the user providing the request. The corrected estimate may also be referred to as a composite value because it is a value based on both the received signal strength data and the motion sensor data.

[0077] The received signal strength may be measured by each of the connected mobile devices 120-122 on a radio frequency signal transmitted by the control unit 110, for example, a Bluetooth beacon transmitted by the control unit 110. The received signal strength may be measured over a period of time and then averaged to generate a received signal strength indicator (RSSI). The RSSI may be generated periodically, for example, every second or every other second.

[0078] The received signal strength may be measured by each of the connected mobile devices 120, 121, 122, for example, on a radio frequency channel between the control unit 110 and each of the connected mobile devices 120-122, as a power level metric over a period of time to generate a received channel power indicator (RCPI).

[0079] The received signal strength measured by each of the one or more connected mobile devices 120-122 during a first predetermined time period is analyzed. The first time period may be, for example, 10 seconds before a motion state request from the control unit 110 is received. The objective is to determine whether the user of the mobile device 120 was approaching or walking away from the control unit 110 during the first time period before the event was generated, for example the last 10 seconds, and whether the received signal strength was constant. A user who may give a request is anyone who is approaching the control unit 110 during the first predetermined time period.

[0080] An estimated time (e.g., in seconds) to reach the radio frequency transceiver 112 may be calculated for each of the connected mobile devices 120-122 based on the received signal strength. The estimated time indicates the duration for the connected mobile devices to reach the control unit 110. The estimated time may indicate a time from a known particular time, such as the time of transmission of the motion status request, or the time of receipt of the motion status request, or a time with a predetermined offset to any of the above times.

[0081] The estimated time may be calculated for each connected mobile device 120-122 and each time each connected mobile device 120-122 receives a motion status request from the control unit 110. For example, the estimated time may be calculated based on a relationship between received signal strength indicator values ​​and time may be defined as a linear model r=at+b, where r is the received signal strength indicator, RSSI, and t is time. If the value of a is positive, the connected mobile device 120 is approaching the control unit 110. A negative value of a means that the connected mobile device 120 is moving away. If α is close to 0, there is no motion. Thus, the parameters a and b may be considered as an estimated constant velocity. The parameters a and b may be estimated, for example, using a "weighted ridge regression" and multiple RSSI values ​​determined from received signal strength data collected over a first predetermined period, e.g., 10 seconds, before the motion status request from the control unit 110 is received. The calculated a and b parameters may be considered as average values ​​during the first predetermined time period, especially if a constant velocity is assumed.

[0082] If constant movement, as defined by a constant speed, is assumed and an RSSI value of Rt=-55 is used as the RSSI value at which the connected mobile device 120 reaches the control unit 110, the time to reach the radio frequency transceiver 112 may be calculated as the time to hit, th, determined as th=(Rt-b) / a, e.g., in seconds. The time th is thus an estimate of how many seconds it would take to reach the threshold Rt if the movement remained constant, i.e., the duration for the connected mobile device 120 to reach the control unit 110.

[0083] To improve validation of the origin of the generated event, motion sensor data from one or more motion sensors, e.g., an accelerometer and / or gyroscope, included in the connected mobile device 120 is taken into account to provide a corrected estimate based on both signal strength and motion sensor data. The motion sensor data may be collected during a second predetermined period of time, e.g., 5 seconds, before a motion status request from the control unit 110 is received by the connected mobile device 120.

[0084] The compensated estimate may be a motion compensated th value, calculated for each connected mobile device 120-122 and each time a connected mobile device 120 receives a motion status request from the control unit 110 by using the collected motion sensor data. The a parameter in the above linear model may be adjusted by the calculated probability p_movement that the connected mobile device 120 is moving, using known methods, such that a_compensated=p_movement*a. Using the RSSI value Rt=-55 when the connected mobile device 120 reaches the control unit 110, a motion compensated th value, indicating the motion compensated duration for the connected mobile device 120 to reach the control unit 110, is calculated as th_compensated=(Rt-b) / a_compensated. This calculation may result in a first connected mobile device 120 that may not be moving or may be moving only at a low speed or low acceleration during a second predetermined time period being subject to a larger increase in the estimated time to reach the radio frequency transceiver 112 than a second connected mobile device 121, where collected motion sensor data indicated that the second connected mobile device 121 was moving more, for example, at a higher speed, or with a higher acceleration, or with a higher angular velocity. The motion compensated th value may be used by the connected mobile device 120 to make a decision as to whether a particular connected mobile device 120 user may have granted a request by comparing it with an appropriate threshold T. If the compensated th value of a certain connected mobile device 120 is higher than T, it is unlikely that the connected mobile device 120 user issued a request. If th_compensated is lower than T, the likelihood is high.

[0085] Motion sensor data may be collected from one or more motion sensors in the connected mobile device 120, for example, in one second segments, for the five seconds prior to when the request is received, and analyzed to determine a motion factor. The motion factor may indicate the degree of change in the motion of the connected mobile device 120, for example, how much the motion of the connected mobile device 120 has increased or decreased. For example, the degree of change in motion may be described by a change in velocity. Such a change in velocity may be related to the acceleration or angular velocity measured by the motion sensor. The motion factor may be provided as a percentage, for example, 0% representing stable stillness and 100% representing a significant increase in motion.

[0086] The corrected estimate may be calculated based on the estimated time and a motion factor. That is, the corrected estimate may be a motion compensated time estimate determined by adjusting the estimated time from the RSSI calculation above with the motion factor. The corrected estimate may be proportional to the received signal strength and inversely proportional to the motion sensor data.

[0087] According to some embodiments herein, the corrected estimate may be calculated by dividing the estimated time derived from the RSS data by a motion factor. Some examples are given below: A shift factor of 50% gives a 100% increase in the estimated RSS time, i.e. corrected estimated time RSS / 0,50 = 2*estimated time from RSS. A shift factor of 75% gives an increase of 33% in the estimated RSS time, i.e. corrected estimated time RSS / 0,75 = 1,33 x estimated time from RSS. A shift factor of 100% leaves the estimated time from RSS unchanged, i.e., corrected estimated time RSS / 1.00 = estimated time from RSS.

[0088] Thus, the corrected estimate indicates the probability that the request is granted by the user of the connected mobile device. If the corrected estimate of the connected mobile device 120 is less than a threshold value, e.g., 10 seconds, it is determined that the user of that particular connected mobile device 120 is likely to have granted the request. In that case, the response to the motion status request is a positive response indicating, for example, "yes, it is likely that my user granted the request." If the connected mobile device 120 is stationary on a desk, its motion factor may be 0%, but the RSS value may still be changing, possibly due to another person moving between the mobile device and the control unit 110. The estimated time from the RSS may then be significantly increased by the motion factor, so that the corrected estimate is greater than 10 seconds, indicating that the user of this connected mobile device 120 is unlikely to have granted the request. In this case, the response to the motion status request is negative, e.g., "no, it is unlikely that my user granted the request."

[0089] The corrected estimate based on received signal strength and motion sensor data may be calculated in any other suitable manner, for example as a motion compensated distance or a motion compensated quality indication. The corrected estimate may directly indicate the probability that a request will be given by a user of connected mobile device 120, or it may be compared to a predetermined value, where the predetermined value is selected to correspond to the method used to calculate the corrected estimate.

[0090] As described above, the corrected estimates may be calculated by each of the one or more connected mobile devices 120-122. The corrected estimates may also be calculated by the control unit 110 for each of the one or more connected mobile devices 120-122.

[0091] operation 205 In response to the motion state request from the control unit 110, the control unit 110 may receive an indication of the probability, or a corrected estimate. In some embodiments, the received corrected estimate comprises an estimate based on the received signal strength data and a motion factor based on the motion sensor data. Thus, the control unit 110 may calculate the corrected estimate based on the received estimate and the motion factor, for example, by applying the methods described above in connection with the description of operation 204.

[0092] When the control unit 110 receives an indication of a probability from the connected mobile device 120, the control unit 110 may base its decision whether to arrange to perform an action directly on the received indication of the probability.

[0093] On the other hand, if the control unit 110 receives a corrected estimate from the connected mobile device 120, the control unit may first determine an indication of the probability based on the corrected estimate and then decide whether to arrange to perform an action. The determination of the indication of the probability may be performed as described above in relation to action 204.

[0094] In yet some other embodiments, control unit 110, in response to the motion state request, receives received signal strength data and motion sensor data from connected mobile device 120. Then, determining an indication of the probability that connected mobile device 120 is associated with the event based on the received signal strength and motion sensor data comprises calculating, by control unit 110, a corrected estimate based on the received signal strength data and the motion sensor data.

[0095] However, because the connected mobile device 120 has direct access to both the signal strength data and the motion sensor data, it may be advantageous to have the connected mobile device 120 calculate a corrected estimate, or at least an estimate and a motion factor, and then transmit the estimate and motion factor, and / or the corrected estimate, and / or an indication of the probability that the connected mobile device 120 is associated with the event to the control unit 110, which then uses the response from the connected mobile device 120 to decide whether or not to perform an action.

[0096] operation 206 The control unit 110 then decides whether to arrange to perform an action based on an indication of the probability that the connected mobile device 120 is associated with the event.

[0097] Determining whether to arrange for the connected mobile device 120 to perform an action based on an indication of a probability associated with an event may include determining to perform the action if the indication of a probability associated with an event by the connected mobile device 120 satisfies a predetermined condition, such as being greater than a predetermined threshold probability.

[0098] In other embodiments, the control unit 110 determines not to perform the action if an indication of the probability that the connected mobile device 120 is associated with the event does not meet a predetermined condition or if there is no response to the motion status request from the connected mobile device 120 within a time limit.

[0099] Operation 207a The requested action may be performed in response to a decision when the control unit 110 determines whether to arrange to perform the action. For example, the door 111b may be unlocked, or unlocked and opened, if the control unit determines to perform the action. This may be, for example, when the connected mobile device 120 sends a response to the motion status request, where the response includes an indication that the connected mobile device 120 is likely to be associated with the event. For example, the response may include a corrected estimated time that is less than a particular time limit, such as less than one second.

[0100] On the other hand, if the control unit 110 decides not to perform an action, the control unit 110 may, for example, keep the door 111b in a locked state.

[0101] If the corrected estimates of a connected mobile device indicate that its user has given the request, an action may be decided to perform the requested action, e.g., to open the door. If the corrected estimates of all connected devices indicate that none of the users of the connected devices has given the request, it may be decided not to perform the requested action, e.g., not to open the door. Since the request may have been given by a user of a mobile device that is not connected, an action may also be decided to release at least one connection between the mobile device and the control unit 110 to allow other mobile devices to connect to the control unit 110. By releasing one connection, this mobile device may connect to the control unit 110 and allow the user of this mobile device to trigger the action.

[0102] Operation 207b If it is decided not to perform the action, the method may further include releasing the connection between the connected mobile device 120 and the control unit 110, or releasing the respective connection between each of the one or more connected mobile devices 120-122 and the control unit 110. In other words, the control unit 110 may disconnect the connected mobile device 120 from the control unit 110, or may disconnect all of the one or more connected mobile devices 120-122 from the control unit 110. The release of the connection, or in other words, the disconnection of the connected mobile devices 120-122, may be advantageous in a scenario where the maximum number of connections of the control unit 110 are used by the connected mobile devices 120-122, but none of the users of the connected mobile devices 120-122 have generated an event in the access control system 100. Alternatively, the request may have been given by a user of a non-connected mobile device 123. By disconnecting the connected mobile device 120-122, i.e., by disconnecting the connected mobile device 120-122, the control unit 110 allows other unconnected mobile devices to connect to the control unit 110, and the search for the connected mobile device 120 associated with the event can then continue.

[0103] Next, an embodiment will be briefly described from the perspective of the connected mobile device 120. FIG. 3 presents a flowchart of a method performed by the connected mobile device 120. As described above, the access application of the connected mobile device 120 may execute or arrange for the connected mobile device 120 to perform some of the following operations. In some embodiments, the respective access application arranges for a cloud service or a web server to perform the following operations. The following operations may refer to, for example, receiving a radio frequency signal transmitted by the access control system 100 used to measure the received signal strength, and / or receiving a motion state request from the control unit 110, and / or determining an indication of the probability, and / or transmitting an indication of the probability and / or a corrected estimate to the control unit 110.

[0104] operation 301 As mentioned above, the connected mobile device 120 receives radio frequency signals transmitted by the access control system 100 which are used to measure received signal strength.

[0105] operation 302 When an event is generated in the access control system, the connected mobile device 120 receives a motion status request from the control unit 110 .

[0106] operation 303 As mentioned above, the connected mobile device 120 may determine an indication of the probability. This may be done according to the embodiments described above in connection with operation 204. For example, the connected mobile device 120 may calculate a corrected estimate based on the received signal strength data and the motion sensor data, and then determine an indication of the probability based on the corrected estimate. The corrected estimate may be compared to a threshold, such as a threshold time to reach the radio frequency transceiver 112, and a corresponding indication of the probability may be determined based on the comparison to the threshold.

[0107] operation 304 As described above, for example in connection with operation 205, in some embodiments, when connected mobile device 120 calculates a corrected estimate based on received signal strength data and motion sensor data, connected mobile device 120 sends an indication of the probability and / or the corrected estimate to control unit 110. Connected mobile device 120 sends the indication of the probability and / or the corrected estimate in response to a motion status request received from control unit 110.

[0108] In some other embodiments, the connected mobile device 120 transmits received signal strength data and motion sensor data to the control unit 110. The control unit 110 then determines an indication of the probability based on the received signal strength data and the motion sensor data. Determining the indication of the probability by the control unit 110 may in this case include calculating a corrected estimate based on the received signal strength data and the motion sensor data.

[0109] As mentioned above, there are different alternatives for how the connected mobile device (120) decides whether or not to arrange to perform an action based on an indication of a probability associated with an event, depending on where the indication of the probability is determined, and also depending on where the corrected estimate is calculated, and also depending on what the response to the motion status request contains.

[0110] For example, if the corrected estimates are calculated by each of one or more connected mobile devices 120-122, the method may further include the following operations shown in FIG.

[0111] Operation 401 In response to the motion status request, each of the one or more connected mobile devices 120-122 may send a response to the control unit 110 based on its corrected estimate.

[0112] To provide a response, the connected mobile device 120 may evaluate whether the corrected estimate satisfies a predetermined condition, which may be met, for example, when the corrected estimate adjusted by the motion sensor data is less than a predetermined threshold, for example 10 seconds, if the composite value is inversely proportional to the motion sensor data.

[0113] Alternatively, for example, if motion sensor data is provided such that when adjusted by the motion sensor data, the corrected estimate is proportional to the motion sensor data, the predetermined condition may be met when the combined value is greater than a predetermined threshold.

[0114] Each of the connected mobile devices 120-122 may send an acknowledgement to the control unit 110 if its corrected estimate satisfies a predefined condition.

[0115] Each of the connected mobile devices 120-122 may send a negative response to the control unit 110, or may not send any response, if its corrected estimate does not satisfy a predefined condition.

[0116] According to some embodiments herein, the connected mobile device 120 may send an acknowledgement with authorization to cause an action. The authorization may be a certificate that the connected mobile device 120 received during an initialization phase indicating that the user of the connected mobile device 120 has the right to access a resource controlled by the control unit 110, e.g., to open a door.

[0117] As already mentioned, in other embodiments, the connected mobile device 120 is already authorized to access the resource when connecting to the control unit 110. Again, the authorization may have been received during the initialization phase. In yet other embodiments, the control unit 110 performs an authorization verification before performing the requested action according to actions 250, 251, or 243.

[0118] Since only one message is sent, sending an acknowledgment together with a grant takes approximately the same time as simply sending an acknowledgment.

[0119] Operation 402 The control unit 110 checks whether any response has been received from one or more of the connected mobile devices 120-122.

[0120] operation 403 If a positive response is received, the control unit 110 arranges to perform the requested action, such as granting access to a physical area, e.g. opening a door, or granting access to the contents of a logical area, a protected device, or a protected resource.

[0121] If the corrected estimates are calculated by the control unit 110, instead of operations 231, 232, and 251, the method may include the following operations shown in FIG.

[0122] operation 501 In response to a status request, a connected mobile device 120 sends its received signal strength data and motion sensor data to the control unit 110 .

[0123] operation 502 The control unit 110 receives received signal strength and motion sensor data sent from one or more connected mobile devices 120-122 and calculates corrected estimates for each of the one or more connected mobile devices 120-122.

[0124] operation 503 The control unit 110 compares each of the corrected estimates with a predefined threshold value. If the corrected estimates from the connected mobile device 120 satisfy a predefined condition, the control unit 110 determines that a user of the connected mobile device 120 has granted a request and arranges to perform the requested action, for example granting access to a physical area, such as opening a door, or granting access to the contents of a logical area, a protected device or a protected resource.

[0125] If no response is received, or only negative responses are received, or all corrected estimates do not satisfy the predetermined condition, the method may further include the following operations.

[0126] operation 504 If no response or a negative response is received from the connected mobile device 120, or if the corrected estimate does not meet the predetermined condition, the control unit 110 may release the connection between the connected mobile device 120 and the control unit 110 to allow other mobile devices to connect to the control unit 110. Release of the connection may be advantageous since a request may be given by a non-connected mobile device 123. By releasing the connection, the non-connected mobile device 123 may connect to the control unit 110, which allows the control unit 110 to verify whether it is the user of the previously non-connected mobile device 123 that has requested to cause an action to occur. Release of the connection between the connected mobile device 120 and the control unit 110 may mean that the physical radio frequency communication channel between the connected mobile device 120 and the control unit 110, which was established during the connection process, is dropped, released, or disconnected. The terminology may vary depending on the type of RF communication protocol used.

[0127] In some embodiments, the control unit 110 may release any of the connections between the control unit 110 and the connected mobile devices 120-122 based on an absent or negative response from the connected mobile device 120, or if a corrected estimate based on the response from the connected mobile device 120 does not satisfy a predetermined condition. That is, the control unit 110 may not necessarily release the connection of the connected mobile device 120 that responded.

[0128] In some other embodiments, the control unit 110 disconnects one or more connections if no response is received from any of the connected mobile devices 120-122, if only negative responses are received, or if each of the corrected estimates does not meet a predetermined condition.

[0129] According to some embodiments herein, disconnecting at least one connection may include disconnecting all of the connected mobile devices 120-122 if no response is received by the control unit 110, or if only a negative response is received, or if the corrected estimate does not meet a predetermined condition. The connections to all mobile devices may be disconnected even if a positive response is received and the control unit 110 would perform an action. In this way, the power consumption of these mobile devices is reduced and also other devices may be allowed to automatically connect to the control unit 110.

[0130] The disconnection may be initiated by the control unit 110, depending on the circumstances, for example, by allocating the physical radio frequency communication channel to another paired mobile device, for example, by returning the previously connected mobile device 120 to an unconnected state.

[0131] In addition to using the motion sensor data to calculate the corrected estimate, the collected motion sensor data may also be used to determine when the mobile device should automatically connect to the control unit 110 as described above. For example, when the mobile device is stationary, it is assumed that the mobile device is resting on a desk and its user is not interested in requesting the control unit 110 to perform an action. Thus, the mobile device does not initiate a process to establish a connection. This conserves the battery life of the mobile device and also prevents blocking available connections with unuseful connections. This is important because there may be a limited number of connections for both the control unit 110 and the mobile device itself. Furthermore, by using the received signal strength data and the motion sensor data, the mobile device can determine whether to connect to the control unit 110 based on factors related to whether the user of the mobile device is likely to issue a request to the control unit 110 in the near future. This ensures that requested actions are performed quickly, since connection time may be omitted.

[0132] As mentioned above, the control unit 110 may also force a disconnection of at least one of the other connections, or may force a disconnection of all connections that returned a negative acknowledgement, which may be done in order to open a new spare connection.

[0133] To prevent a ping-pong effect related to disconnecting and reconnecting, reconnection of the now disconnected, previously connected mobile device 120 may be prohibited for at least a certain period of time, such as a prohibition or backoff time period. For example, automatic reconnection may be prohibited during the prohibition period. Problems arise in such a scenario. For example, after the forced disconnection of the previously connected mobile device 120, a further request may be given by the user of the previously connected mobile device 120 to arrange for the control unit 110 to perform an action. For example, the user of the previously connected mobile device 120 gives a command to unlock or open the door 111b.

[0134] However, if the control unit 110 is limited to investigating whether to perform an action in response to a further event based on communication with the currently connected mobile device, the above problem not only may a user of a previously connected and now forcibly disconnected mobile device 120 be prohibited from reconnecting to the control unit 110 by the above method, but also may lead to the control unit 100 not being able to determine that it was the user of the disconnected mobile device that provided the request, and as a result the control unit 110 may not perform the requested action if it was the user of the disconnected mobile device that provided the request.

[0135] In other words, there may be a back-off time such that a previously connected mobile device 120 (including its applications) can automatically reconnect to the control unit 110, after which the previously connected mobile device is free to connect again to the control unit 110. However, such a back-off time stops a user of a previously connected mobile device 120 from requesting the control unit 110 to arrange to perform a requested action, e.g., arrange to open a door, within this back-off time.

[0136] The embodiments herein solve the above problem by allowing a previously connected mobile device 120 to reconnect based on an indication of whether a second event has been generated. Specifically, if the indication of whether a second event has been generated indicates that a second event has been generated, the previously connected mobile device 120 is permitted to reconnect during the backoff period. This solution may also include not allowing a previously connected mobile device 120 to reconnect during the backoff period if the indication of whether a second event has been generated indicates that a second event has not been generated.

[0137] The decision whether to allow a reconnection may be made, for example, both by the control unit 110 after receiving a reconnection attempt and by the previously connected mobile device 120 prior to the reconnection attempt. By having the previously connected mobile device 120 make the decision, fewer failed reconnection attempts will occur.

[0138] To allow the previously connected mobile device 120 to make a decision as to whether or not to allow a reconnection, and to prevent a reconnection attempt from being made when such an attempt should not be made, the control unit 110 may send, for example in a broadcast transmission, to the previously connected mobile device 120 an indication of whether or not a second event was generated. This may be implemented, for example, in the form of a value of a counter of events.

[0139] Therefore, there is a fail-safe mechanism as described above so that the user of a previously connected mobile device 120 does not stop requesting the control unit 110 to arrange to perform a requested action, e.g. arrange to open a door, within the back-off time.

[0140] In some embodiments, the control unit 110 maintains a counter of the number of times the door open command is initiated. The value of this counter may be transmitted along with the Bluetooth Hello message.

[0141] When a previously connected mobile device 120 is forced to disconnect, it may not reconnect until the open door command counter is incremented, which means not before someone gives an open door command again or when the timer corresponding to the backoff time expires.

[0142] In the following, a method for solving the above problem is explained in detail with reference to the signaling diagram presented in Fig. 5b and with further reference to the access control system 100 shown in Fig. 1a and 1b. The signaling diagram in Fig. 5b shows a method for handling a radio frequency connection between the control unit 110 of the access control system 100 and a connected mobile device 120.

[0143] The method is illustrated by reference to Bluetooth® terminology, however, the method is equally applicable to other radio frequency communication protocols.

[0144] Although the method is described below with respect to a connected mobile device 120, the method may be applied to multiple connected mobile devices 120-122 in parallel or serially.

[0145] As mentioned above, the access control system comprises a control unit 110 connected to one or more mobile devices 120-122 using radio frequency signal communication.

[0146] One or more of the following operations presented in FIG. 5b may be performed in the following example order: In other examples, the order may differ from that described below. The method may include the following operations:

[0147] operation 551 At some point, a radio frequency connection is established between the control unit 110 and the connected mobile device 120. In some embodiments herein, the connection is established automatically when the connected mobile device 120 is close enough to the control unit 110 to receive a Hello message.

[0148] operation 552 The control unit 110 can then keep track of the number of events generated, so that the control unit 110 can make decisions regarding whether to allow a connected mobile device 120 to reconnect in the future when it becomes disconnected, and to avoid reconnection attempts when such attempts should not be made. The tracking may be performed by an event counter, which may be given an initial value, e.g., zero, at some point.

[0149] operation 553 The control unit 110 may broadcast an indication of whether an event has been generated. For example, the control unit 110 may broadcast a counter value. The counter value may correspond to the number of events that have been generated.

[0150] An indication of whether an event has been generated may be broadcast in a Hello message sent by the control unit 110, for example, using Bluetooth.

[0151] A connected mobile device 120 may receive an indication of whether an event has been generated, for example, by a broadcast transmission from the control unit 110. For example, a connected mobile device 120 may receive a counter value.

[0152] operation 554 If a connected mobile device 120 receives an indication of whether an event has been generated, it may track the number of events generated. For example, the connected mobile device 120 may use the received counter value to start or update its own counter of events.

[0153] operation 555 The control unit 110 obtains an indication of a first event generated in the access control system 100 in response to a first request for the control unit 110 to arrange to perform an action.

[0154] An event generated in the access control system 100 may be the result of a request provided by a user of a mobile device 120 of one or more mobile devices 120-123.

[0155] operation 556 The control unit 110 may adjust the counter of the event to a first counter value in response to the first event. Adjusting the counter may include, for example, incrementing the counter. The counter may be incremented by 1 in response to an event, such as the first event.

[0156] operation 557 In some embodiments, the connected mobile device 120 obtains an indication of the first event. For example, the control unit 110 may broadcast the first counter value to be received by all mobile devices 120-122, including the connected mobile device 120, within range of a radio frequency communication used by the control unit 110 when communicating with the connected mobile devices 120-123.

[0157] An indication of the first event, such as the first counter value, may be broadcast in a Hello message sent by the control unit 110, for example, using Bluetooth.

[0158] In some embodiments, the indication of the first event includes a first counter value corresponding to the first event.

[0159] operation 558 In response to the first event, the connected mobile device 120 may adjust the event counter to a first counter value.

[0160] operation 559 Then, the control unit 110 releases the radio connection between the mobile device 120 and the control unit 110 in response to the occurrence of the first event. For example, the control unit 110 may release the radio frequency connection between the connected mobile device 120 and the control unit 110 to allow another mobile device to be connected to the control unit 110. Release of the connection may be advantageous since a request may be given by a non-connected mobile device 123. By releasing the connection, the non-connected mobile device 123 may be able to connect to the control unit 110, which allows the control unit 110 to verify whether it is the user of the previously non-connected mobile device 123 that has requested to cause an action. Release of the radio frequency connection between the connected mobile device 120 and the control unit 110 may mean that the physical radio frequency communication channel between the connected mobile device 120 and the control unit 110, which was established during the connection process, is dropped, released, or disconnected. The disconnection may be initiated by the control unit 110, depending on the circumstances, for example, by allocating the physical radio frequency communication channel to another paired mobile device, for example, by returning the previously connected mobile device 120 to an unconnected state.

[0161] The mobile device 120 may be prohibited from reconnecting to the control unit 110 within a predetermined duration of the disconnection unless a second event is generated during the predetermined duration.

[0162] In some embodiments herein, the disconnection by the control unit 110 is performed in response to an inability to determine which of the one or more connected mobile devices 120-122 is associated with the event.

[0163] In some further embodiments herein, a disconnection is performed by the control unit 110 if the number of connected mobile devices is greater than the maximum number of mobile devices allowed to be simultaneously connected to the control unit 110.

[0164] In some further embodiments herein, the disconnection by the control unit 110 is performed in response to being unable to determine which of one or more connected mobile devices 120-122 is associated with the event when the number of connected mobile devices is greater than the maximum number of mobile devices allowed to be simultaneously connected to the control unit 110. That is, the above embodiments may be combined.

[0165] In some embodiments, the control unit 110 can disconnect any of the connections between the control unit 110 and the connected mobile devices 120-122, for example one or more of the connections.

[0166] The control unit 110 may select the radio frequency connection between a connected mobile device 120 and the control unit 122 to be released by selecting the connection to be released from among one or more connections between the control unit 110 and one or more connected mobile devices 120-110 based on which connection was established first.

[0167] In some other embodiments, the at least one connection to be disconnected may be selected based on an analysis of the distance and movement of the connected mobile devices 120-122, such that connected mobile devices that are farther away and / or less moving are disconnected first.

[0168] operation 560a The control unit 110 may start an inhibit timer in response to a disconnection of a previously connected mobile device 120. The inhibit timer may also be referred to as a back-off timer. When an inhibit timer is used and a previously connected mobile device 120 expires, the mobile device 102 is allowed to reconnect, for example, by automatically reconnecting when it is able to communicate with the control unit 110. For example, a previously connected mobile device 120 may be allowed to automatically reconnect upon receiving a Hello message from the control unit 110.

[0169] operation 560b Additionally, a previously connected mobile device 120 may start a prohibit timer in response to a disconnection from the previously connected mobile device 120 .

[0170] operation 561 After the control unit 110 releases the connection, the control unit 110 obtains an indication of whether a second event was generated in the access control system 100 in response to the second request for the control unit 110 to arrange to perform an action. For example, the control unit 110 may obtain an indication that a second event was generated in the access control system 100 in response to the second request for the control unit 110 to arrange to perform an action. For example, a user of a previously connected mobile device 120 may have given a command to open the door 111b in the request receiving unit 113.

[0171] operation 562 The control unit 110 may adjust the counter of the event to a second counter value in response to a second event, ie, when a second event is generated.

[0172] operation 563 In some embodiments, the previously connected mobile device 120 obtains an indication of the second event. For example, the control unit 110 broadcasts information indicating whether the second event occurred. The control unit 110 may broadcast an indication of whether the second event was generated in response to a second request for the control unit 110 to arrange to perform an action.

[0173] Correspondingly, obtaining an indication of whether the second event was generated may then comprise receiving an indication by the previously connected mobile device 120. Thus, the indication of whether the second event was generated may be received in a message broadcast from the control unit 110.

[0174] When the indication of the second event includes a counter value corresponding to the second event, broadcasting the indication of whether the second event was generated includes broadcasting the second counter value.

[0175] An indication of the second event, such as the second counter value, may be broadcast in a Hello message sent by the control unit 110, for example, using Bluetooth.

[0176] operation 564 The previously connected mobile device 120 may adjust the counter of the event to a second counter value in response to a second event, i.e., when a second event is generated. That is, the previously connected mobile device 120 may adjust the counter of the event to a second counter value in response to an obtained indication of a second event. For example, the previously connected mobile device 120 may adjust the counter of the event to a second counter value if it receives a counter value from the control unit 110, such as a second counter value that is different from a first counter value stored in the previously connected mobile device 120.

[0177] operation 565 In some embodiments, the previously connected mobile device 120 then determines whether to allow the mobile device 120 to reconnect to the control unit 110 based on an indication of whether a second event was generated.

[0178] Determining whether to allow the mobile device 120 to reconnect to the control unit 110 may include determining whether to send a connection request by the mobile device 120. The connection request may be a reconnection request.

[0179] In some embodiments, determining whether to allow the mobile device 120 to reconnect to the control unit 110 is further based on a comparison of the duration since the disconnection and a predefined duration since the disconnection. The predefined period since the disconnection may be, for example, a backoff time or a prohibition time indicating a time during which a previously connected mobile device 120 is prohibited from reconnecting to the control unit 110. The determining may be performed within a predefined time. Once the predefined time has elapsed, the previously connected mobile device 120 is free to reconnect, for example, without considering an indication of whether a second event was generated.

[0180] The previously connected mobile device 120 determines to allow the mobile device 120 to reconnect to the control unit 110 if the indication of whether a second event has been generated indicates that a second event has been generated.

[0181] When the indication of the second event includes a counter value corresponding to the second event, determining whether to allow the mobile device 120 to reconnect to the control unit 110 includes determining to allow the mobile device 120 to reconnect to the control unit 110 based on the value of the event counter when the value of the event counter is adjusted to the second counter value.

[0182] operation 566 In some embodiments, the control unit 110 receives a connection request from the mobile device 120. The connection request may be received within a predetermined time from the release of the connection.

[0183] operation 567 In some embodiments, the control unit 110 determines whether to allow the mobile device 120 to reconnect to the control unit 110 based on an indication of whether the second event was generated. For example, the control unit 110 may determine whether to allow the mobile device 120 to reconnect to the control unit 110 when a connection request is received from the mobile device 120. In some embodiments, the previously connected mobile device 120 connects to the control unit 110, and the control unit 110 again forces the mobile device 120 to disconnect.

[0184] In some embodiments, the determining whether to allow the mobile device 120 to reconnect to the control unit 110 is further based on a comparison of the duration since the disconnection and a predefined duration since the disconnection. The determining may be performed within a predefined time, which may be the backoff or inhibit time mentioned above. Once the predefined time has elapsed, the previously connected mobile device 120 is free to reconnect.

[0185] The control unit 110 determines to allow the mobile device 120 to reconnect to the control unit 110 if the indication of whether a second event has occurred indicates that a second event has been generated. The second event may have been generated within a predetermined time period.

[0186] When the indication of the second event includes a counter value corresponding to the second event, determining whether to allow the mobile device 120 to reconnect to the control unit 110 includes determining to allow the mobile device 120 to reconnect to the control unit 110 based on the value of the event counter when the value of the event counter is adjusted to the second counter value.

[0187] Enumerated exemplary embodiments of a method for handling a radio frequency connection between the control unit 110 and the mobile device 120 now follow below.

[0188] 1. A method for processing a radio frequency connection between a control unit 110 of an access control system 100 and a mobile device 120, comprising: obtaining an indication of a first event generated in the access control system 100 in response to a first request to arrange for the control unit 110 to perform an action; obtaining an indication of whether a second event was generated in the access control system 100 in response to a second request for the control unit 110 to arrange for the control unit 110 to perform an action after the disconnection; A method for determining whether to allow the mobile device 120 to reconnect to the control unit 110 based on an indication of whether the second event was generated.

[0189] 2. Determining whether to allow the mobile device 120 to reconnect to the control unit 110 The method of exemplary embodiment 1, comprising determining to allow the mobile device 120 to reconnect to the control unit 110 if the indication of whether the second event has been generated indicates that the second event has been generated.

[0190] 3. The method of exemplary embodiment 1 or 2, wherein the mobile device 120 is prohibited from reconnecting to the control unit 110 within a predetermined duration from the disconnection unless a second event is generated during the predetermined duration.

[0191] 4. The method of any one of exemplary embodiments 1-3, further comprising the control unit 110 broadcasting an indication of whether the second event has been generated.

[0192] 5. each representation of the first event and the second event includes a respective counter value corresponding to each event; adjusting a counter of events to a first counter value in response to the first event; The control unit 110 broadcasts the first counter value; adjusting the counter to a second counter value when the second event is generated; The method of exemplary embodiment 4, wherein broadcasting the indication of whether the second event was generated includes broadcasting the second counter value, and determining whether to allow the mobile device 120 to reconnect to the control unit 110 further includes determining, based on the value of the event counter, to allow the mobile device 120 to reconnect to the control unit 110 if the value of the event counter is adjusted to the second counter value.

[0193] 6. A method according to any of exemplary embodiments 1 to 5, further comprising receiving a connection request from the mobile device 120 by the control unit 110, and determining whether to allow the mobile device 120 to reconnect to the control unit 110, the method being executed by the control unit 110.

[0194] 7. A method according to any of exemplary embodiments 1 to 5, wherein obtaining an indication of whether or not a second event has been generated includes receiving an indication by the mobile device 120, the indication of whether or not a second event has been generated being received in a message broadcast from the control unit 110, and determining whether or not to allow the mobile device 120 to reconnect to the control unit 110 includes determining whether or not to send a connection request by the mobile device 120.

[0195] 8. The method of any of example embodiments 1-7, wherein the disconnection by the control unit 110 is performed in response to an inability to determine which of the one or more connected mobile devices 120-122 is associated with the event.

[0196] 9. The method according to any of the exemplary embodiments 1 to 8, wherein the control unit 110 terminates the connection if the number of connected mobile devices is greater than the maximum number of mobile devices allowed to be simultaneously connected to the control unit 110.

[0197] 10. The method according to any of the exemplary embodiments 1-9, wherein an event generated in the access control system 100 is the result of a request provided by a user of one of the one or more mobile devices 120-123.

[0198] 11. The method of any of exemplary embodiments 1-10, further comprising selecting, by the control unit 110, the radio frequency connection between the mobile device 120 and the control unit 110 to be released by selecting the connection to be released from among one or more connections between the control unit 110 and one or more connected mobile devices 120-122 based on which connection was established first.

[0199] 12. An access control system 100 configured to perform a method according to any one of exemplary embodiments 1 to 11, the access control system 100 including a control unit 110 and a mobile device 120 configured to be connected to the control unit 110 using radio frequency signal communication.

[0200] 13. The access control system 100 of exemplary embodiment 12, wherein the mobile device 120 is any one of a mobile phone, a tablet, a laptop, a key fob, a smart watch, or a smart bracelet, the control unit 110 is any unit that controls access to a physical area, a logical area, a protection device, or a protected resource, and the access control system 100 is configured to generate an event in response to a request from a user of one of the mobile devices 120 requesting access to the content of the physical area, the logical area, the protection device, or the protected resource.

[0201] 14. A computer program 603, 703 comprising computer readable code units which, when executed on the access control system 100, cause the access control system 100 to perform the method according to any of the exemplary embodiments 1-11.

[0202] 15. A method for processing a radio frequency connection between a control unit 110 of an access control system 100 and a mobile device 120, the method being performed by the control unit 110 of the access control system 100, the method comprising: obtaining an indication of a first event generated in the access control system 100 in response to a first request to arrange for the control unit 110 to perform an action; Disconnecting the radio frequency connection between the mobile device 120 and the control unit 110; The method includes broadcasting an indication of whether a second event was generated in the access control system 100 in response to a second request to arrange for the control unit 110 to perform an action.

[0203] The method for determining whether to arrange to perform an action in response to a generated event may be implemented in any access control system for access control of a physical area, a logical area, a protected device, or a protected resource, etc., such as the access control system 100 shown in Figures 1a and / or 1b. Thus, the access control system 100 is configured to determine whether to arrange to perform an action in response to a generated event. Thus, the access control system 100 is configured to perform at least the described embodiment by performing corresponding method actions as described above.

[0204] The generated event may be the result of a request issued by a user, requesting the control unit 110 to arrange access to a physical area, a logical area, a protected device, or a protected resource, etc. As shown in Figures 1a and 1b, the access control system 110 comprises a control unit 110 and one or more connected mobile devices 120-122. As mentioned above, each of the one or more connected mobile devices 120-122 may be any one of a mobile phone, a tablet, a laptop, a key fob, a smart watch, or a smart bracelet.

[0205] The control unit 110 may be any unit that controls access to a physical domain, a logical domain, a protected device, or a protected resource.

[0206] An embodiment of a control unit 600 will be further explained with reference to the schematic block diagram shown in Figure 6, and an embodiment of a connected mobile device 700 will be further explained with reference to the schematic block diagram shown in Figure 7. The control unit 600 corresponds to the control unit 110 of Figures 1a and 1b, and the connected mobile device 700 corresponds to the connected mobile device 120 of Figures 1a and 1b.

[0207] The control unit 600 and the connected mobile device 700 may each comprise a processing module 601, 701 such as means for carrying out the methods described herein. The means may be embodied in the form of one or more hardware modules and / or one or more software modules.

[0208] The control unit 600 and the connected mobile device 700 may further comprise a memory 602, 702, respectively. The memory may include, e.g., contain or store, instructions, e.g., in the form of a computer program 603, 703, which may comprise computer readable code units that, when executed on the control unit 600 and / or the connected mobile device 700, cause the control unit 600 and / or the connected mobile device 700 to perform the methods described above.

[0209] According to some embodiments herein, the control unit 600 and / or the connected mobile device 700 and / or the processing module 601, 701 include a processing circuit 604, 704 as an example hardware module that may include one or more processors. Thus, the processing module 601, 701 may be embodied in the form of the processing circuit 604, 704 or "implemented" by the processing circuit 122, 123. Instructions may be executable by the processing circuit 604, 704, such that the control unit 600 and / or the connected mobile device 700 is operable to perform the methods described above. As another example, the instructions, when executed by the control unit 600 and / or the connected mobile device 700 and / or the processing circuit 604, 704, may cause the control unit 600 and / or the connected mobile device 700 to perform the methods described above.

[0210] In view of the above, in one example, an access control system 100 comprising a control unit 600 and a connected mobile device 700 is provided for determining whether to arrange to perform an action in response to an event generated within the access control system 100. Again, the memory 602, 702 includes instructions executable by said processing circuitry 604, 704, whereby the control unit 600 and / or the connected mobile device 700 are operable to perform the method described above with respect to Figures 2 and 3. The method comprises transmitting, by the radio frequency transceiver 112, a radio frequency signal to be used for measuring received signal strength by one or more connected mobile devices 120-122. The method further comprises sending, by the control unit 110, a motion status request to a connected mobile device 120 of the one or more connected mobile devices 120-122 in response to the generated event.

[0211] The method further comprises determining 204 an indication of a probability that the connected mobile device 120 is associated with the event. Determining the indication of the probability is based on received signal strength data and motion sensor data of the connected mobile device 120. The received signal strength data is based on radio frequency signals measured by the connected mobile device 120 and transmitted during a first predetermined period of time before the motion status request from the control unit 110 is received. The motion sensor data is collected from a motion sensor included in the connected mobile device 120 during a second predetermined period of time before the motion status request from the control unit 110 is received.

[0212] The method further includes determining, by the control unit 110, whether to arrange for the connected mobile device 120 to perform an action based on the indication of the probability associated with the event.

[0213] In some embodiments, the control unit 600 and / or the connected mobile device 700 and / or the processing module 601, 701 may comprise, as exemplary hardware modules, one or more of a transceiver module 631, 731 for RF communication, a determination module 610, 710, and a calculation module 620, 720. In other examples, one or more of the exemplary hardware modules mentioned above may be implemented as one or more software modules.

[0214] According to various embodiments described above, the transceiver module 631 of the control unit 110, 600 is configured to transmit radio frequency signals used for measuring received signal strength by one or more connected mobile devices 120-122. The transceiver module 631, 731 may be further configured to transmit and / or receive motion status requests and responses to the motion status requests.

[0215] According to various embodiments described above, the determination module 610, 710 is configured to determine an indication of the probability that the connected mobile device 120, 700 is associated with an event.

[0216] The decision module 610 of the control unit is further configured to decide whether to arrange for the connected mobile device to perform an action based on an indication of the probability associated with the event.

[0217] Additionally, the calculation module 620, 720 may be configured to calculate an estimate indicative of a probability that the connected mobile device 120, 700 is associated with the event based on the received signal strength data, and may be further configured to calculate a corrective motion factor based on the motion sensor data, and to adjust the estimate with the corrective motion factor to obtain a corrected estimate indicative of the probability.

[0218] Furthermore, the processing module 601, 701 may comprise an input / output unit 606, 706. According to an embodiment, the input / output unit 606 of the control unit 600 may comprise a command receiving unit, for example a request receiving unit 113.

[0219] The control unit 600 may further comprise an activation module 630 which may be arranged to perform an action requested by a user of a connected mobile device 120-122. The activation module 630 may for example be arranged to unlock the lock 111a of the door 111b in response to a request to unlock the lock 111a.

[0220] The connected mobile device 700 may further include a motion sensor 750 for generating motion sensor data.

[0221] The control unit 600 and / or the connected mobile device 700 and / or the processing module 601, 701 may further comprise one or more of an acquisition module 640, 740 and an adjustment module 660, 760. The acquisition module 640, 740 may obtain an indication of whether an event has occurred. The adjustment module 660, 760 may adjust a counter of the event.

[0222] The decision module 610, 710 may be further configured to determine whether to allow the mobile device 120 to reconnect to the control unit 110 based on the indication of whether the second event was generated.

[0223] In summary, the access control system 100 and the method for determining whether to arrange to perform an action in response to a generated event as described above have several advantages. It allows monitoring the behavior of users of connected mobile devices and arranging access for those who actually have the intention to gain access and the correct access rights. Prevents giving access to anyone not authorized to issue requests on or at the control unit 110, 600, as well as the user of the mobile device, when the mobile device is near the control unit 110, 600 with an active connection, but the user has not issued a request. The requested access can be arranged in a secure manner: for example, the control unit 110, 600 initiates a verification process when a request is given to the control unit 110, 600 by sending a motion status request to all connected mobile devices and, based on the response, verifies whether the request is given by a user of a connected mobile device who has the intention and the access rights to gain access. Allows monitoring many mobile devices at once and prioritizing them, thus allowing incoming users that exceed the maximum number of current connections to be connected, while inactive users or users that are simply passing through are disconnected, i.e., disassociated. The response time of the control unit 110, 600 following an event that has occurred is reduced. This is achieved by connecting the mobile device when it is within range of the control unit 110, 600. If the event is the result of a request, for example in the form of pressing a button on or at the control unit 110, 600 or touching a touch screen, given by a user of a mobile device already connected to the control unit 110, 600, the control unit 110, 120 quickly verifies the request and arranges the requested action.

[0224] When the word "comprise" or "comprising" is used, it is to be construed as open-ended, i.e., meaning "consisting of at least".

[0225] The embodiments of the present specification are not limited to the above-mentioned preferred embodiments. Various alternatives, modifications, and equivalents may be used. Therefore, the above-mentioned embodiments should not be interpreted as limiting the scope of the present invention, which is defined by the appended claims.

Claims

1. A method performed in an access control system (100) for determining whether to arrange to perform an action in response to an event generated in the access control system (100), the access control system comprising a control unit (110) connected to a plurality of mobile devices (120-122) using radio frequency signal communication and further comprising a radio frequency transceiver (112), the event indicating a request for the control unit (110) to arrange to perform the action, the method comprising: transmitting (201) by said radio frequency transceiver (112) a radio frequency signal for use in measuring received signal strength by said plurality of connected mobile devices (120-122); sending (203) a motion status request by the control unit (110) to each connected mobile device (120) of the plurality of connected mobile devices (120-122) in response to the generated event; determining (204), by the control unit (110) or each connected mobile device (120), an indication of a probability that each connected mobile device (120) is associated with the event, wherein determining the indication of the probability is based on received signal strength data and motion sensor data of each connected mobile device (120), the received signal strength data being based on the radio frequency signals measured by each connected mobile device (120) and transmitted during a first predetermined time period prior to receiving the motion status request from the control unit (110) and the motion sensor data being collected from a motion sensor (750) included in each connected mobile device (120) during a second predetermined time period prior to receiving the motion status request from the control unit (110), the motion status request serving as a trigger for each connected mobile device (120) to compile received signal strength data and motion sensor data used to determine the indication of the probability that each connected mobile device (120) is associated with the event; determining (206), by the control unit (110), whether to arrange for each connected mobile device (120) to perform the action based on the indication of the probability associated with the event.

2. Determining whether to arrange for each connected mobile device (120) to perform an action based on an indication of a probability associated with an event, comprising: determining that the respective connected mobile device (120) performs the action if the representation of the probability associated with the event satisfies a predefined condition; or 2. The method of claim 1, further comprising: determining not to perform the action if the indication of the probability associated with the event by each connected mobile device (120) does not satisfy the predetermined condition or if there is no response from each connected mobile device (120) to the motion status request within a time limit.

3. Determining the indication of the probability comprises: calculating an estimate indicative of a probability that each connected mobile device (120) is associated with the event based on the received signal strength data; calculating a corrective motion factor based on the motion sensor data; 3. A method according to claim 1 or 2, comprising adjusting the estimate with the corrective motion factor to obtain a corrected estimate indicative of the probability.

4. The method of claim 3, wherein determining the indication of probability includes comparing a corrected estimate indicating the probability that each connected mobile device (120) is associated with the event to a predetermined threshold value corresponding to a predetermined probability that each connected mobile device (120) is associated with the event. [0020] Claim 5: Determining the indication of the probability based on the received signal strength data and motion sensor data includes calculating, by the each connected mobile device (120), the corrected estimate based on the received signal strength data and motion sensor data, the method comprising:

5. The method of claim 3 or 4, further comprising transmitting (304) the indication of the probability and / or the corrected estimate to the control unit (110) by the respective connected mobile device (120) in response to the motion status request from the control unit (110).

6. A method as described in claim 3 or 4, further comprising receiving (205), by the control unit (110), in response to the motion status request, the received signal strength data and motion sensor data from each connected mobile device (120), and determining the indication of the probability that each connected mobile device (120) is associated with the event based on the received signal strength data and motion sensor data comprises calculating, by the control unit (110), the corrected estimate based on the received signal strength data and motion sensor data.

7. The corrected estimate corresponds to a corrected estimated time to reach the radio frequency transceiver (112), and calculating the corrected estimated time comprises: calculating an estimated time for each connected mobile device (120) to reach the radio frequency transceiver (112) based on the received signal strength data; calculating a corrective motion factor based on the motion sensor data; A method according to any one of claims 3 to 6, comprising adjusting the estimated time by the motion factor to obtain the corrected estimated time.

8. A method according to any one of claims 3 to 7, wherein the motion coefficient indicates a measure of change in motion of each connected mobile device (120).

9. A method according to any one of claims 1 to 8, wherein the motion sensor data includes acceleration data and / or rotational speed data.

10. A method according to any one of claims 1 to 8, wherein the request for the control unit (110) to arrange to perform the action comprises a request to grant access to a physical area, a logical area, a protected device (111a, 111b), or a protected resource, and determining whether to arrange to perform an action in response to the generated event comprises determining whether to grant access to the physical area, the logical area, the protected device (111a, 111b), or the protected resource.

11. If it is determined not to perform the action, the method further comprising: Disconnecting (207b) the connection between each connected mobile device (120) and the control unit (110); or The method of any one of claims 2 to 10, further comprising disconnecting (207b) a respective connection between each of the plurality of connected mobile devices (120-122) and the control unit (110).

12. A method according to any one of claims 1 to 10, wherein an event generated in the access control system (100) is the result of a request given by a user of a mobile device (120-123).

13. A method according to any one of claims 1 to 12, wherein the motion status request requests each connected mobile device (120) to respond with an indication of the probability that each connected mobile device (120) is associated with the event.

14. An access control system (100) configured to perform the method of any one of claims 1 to 13, comprising a control unit (110) configured to be connected to a plurality of connected mobile devices (120-122), each one of the plurality of connected mobile devices (120-122) being one of a mobile phone, a tablet, a laptop, a key fob, a smart watch, or a smart bracelet, and the control unit (110) being any unit that controls access to a physical area, a logical area, a protected device, or a protected resource.

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