Patent Description:
An elevator system comprises at least one elevator car arranged to travel along a respective at least one elevator shaft and an elevator control unit for controlling operations of the elevator system. Typically, a travelling cable is used to connect electrical devices of the at least one elevator car to the elevator control unit. Typically, in the elevator systems, especially in high-rise elevator systems, the travelling cable is a costly component, an installation of the travelling cable is time-consuming, a cable drum may be difficult to handle due to its size and weight, and the travelling cable may get easily damaged, which in turn leads to a costly replacement of the travelling cable and unnecessary downtime of the elevator system.

The travelling cable may be replaced with a wireless communication system to connect the electrical devices of the at least one elevator car to the elevator control unit by using a wireless communication technology. However, an implementation of a reliable wireless communication system that meets strict requirements set by, for example safety regulations, may be difficult.

The reliability of the wireless communication system may be reduced because of several reasons, e.g. communication distance, interferences in the communication system, and/or sway of a suspension device of the elevator car blocking a line of sight. Typically, the communication connection is lost only temporarily, but since an elevator safety system requires continuous communication, even a short break in the communication leads to an elevator emergency stop.

Thus, there is a need to develop solutions in order to improve at least partly reliability of wireless communication of an elevator system.

A patent publication <CIT> discloses an elevator system includes a controller; an elevator car; an elevator car controller mounted on the elevator car; a transceiver on the elevator car; and an access point. The transceiver and the access point are configured to provide wireless communications between the controller and the elevator car controller over a first communications path and a second communications path. <CIT> is the closest prior art document of the present invention.

A patent publication <CIT> discloses an elevator system provided an elevator wireless communication system with a redundant fault-tolerant function.

A patent publication <CIT> discloses a data transmission device for an elevator, which can transmit and receive data among a plurality of radio transmission means without fail.

A patent publication <CIT> discloses an elevator system comprising an elevator car configured for traveling along a hoistway; a sensor configured for determining the current position of the elevator car within the hoistway; at least one stationary wireless communication module arranged within or close to the hoistway; and a mobile wireless communication module attached to the elevator car. The wireless communication modules are configured for communication via one of a plurality of radio channels.

An objective of the invention is to present an elevator system, a method, and a computer program for selecting a wireless communication system. Another objective of the invention is that the method, and a computer program for selecting a wireless communication system improve at least partly reliability of wireless communication of an elevator system.

The objectives of the invention are reached by an elevator unit, a method, and a computer program as defined by the respective independent claims.

According to a first aspect, an elevator system for selecting a wireless communication system according to claim <NUM> is provided.

The elevator control unit may further be configured to select another wireless communication system from amongst the at least two wireless communication systems to be used to provide the wireless communication connection between the elevator control unit and the car control unit, in response to that the elevator control unit detects based on the obtained selection data that said another wireless communication system is the most appropriate at a later point of time. The at least one selection parameter may be predefined or defined dynamically on a need-basis.

In some embodiments, the at least one wireless communication system related selection parameter may comprise detected interference in the wireless communication system.

The at least two wireless communication systems may differ from each other by at least one of a frequency band, a modulation technique, a power level, an antenna type, and/or antenna properties.

In some embodiments, the at least two wireless communication systems may differ from each other by a communication technology.

The different communication technologies of the at least two wireless communication systems may comprise at least two of the following communication technologies: a point-to-point microwave link, <NUM>, a free space optical communication technology, Bluetooth (BT), Zigbee, so that each wireless communication system is based on a different communication technology than the other wireless communication systems.

According to a second aspect, a method for selecting a wireless communication system for providing wireless communication connection between an elevator control unit and a car control unit arranged to an elevator car according to claim <NUM> is provided.

The method may further comprise selecting another wireless communication system from amongst the at least two wireless communication systems to be used to provide the wireless communication connection between the elevator control unit and the car control unit, in response to detecting based on the selection data that said another wireless communication system is the most appropriate at a later point of time.

The at least one selection parameter may be predefined or defined dynamically on a need-basis.

The different communication technologies of the at least two wireless communication systems may comprise at least two of the following communication technologies: a point-to-point microwave link, <NUM>, a free space optical communication technology, Bluetooth (BT), or Zigbee, so that each wireless communication system is based on a different communication technology than the other wireless communication systems.

According to a third aspect, a computer program is provided, wherein the computer program comprises instructions which, when the program is executed by an elevator control unit of the elevator system according to the first aspect, cause the elevator control unit to carry out the method as described above.

The features recited in dependent claims are mutually freely combinable within the scope of the appended claims.

<FIG> illustrates schematically an example of an elevator system <NUM> for selecting a wireless communication system. The elevator system <NUM> comprises an elevator car <NUM> arranged to travel along an elevator shaft <NUM> between a plurality of landings, a car control unit <NUM>, and an elevator control unit <NUM>. The car control unit <NUM> is arranged to the elevator car <NUM>, e.g. to a rooftop of the elevator car <NUM> as illustrated in the example of <FIG>. The elevator system <NUM> of the example of <FIG> comprises one elevator car <NUM> travelling along one elevator shaft <NUM>, however the elevator system <NUM> may also comprise an elevator group, i.e. group of two or more elevator cars <NUM> each travelling along a separate elevator shaft <NUM> configured to operate as a unit serving the same landings (for sake of clarity the plurality of landings are not illustrated in <FIG>). The elevator system <NUM> further comprises an elevator control system <NUM>, e.g. an elevator controller, <NUM>. The elevator control system <NUM> may be configured to control the operation of the elevator system <NUM> at least in part. The elevator control system <NUM> may reside e.g. in a machine room (for sake of clarity not shown in <FIG>) or in one of the landings of the elevator system <NUM>. The elevator system <NUM> may further comprise one or more other known elevator related entities, e.g. hoisting system, user interface devices, safety circuit and devices, elevator door system, etc., which are not shown in <FIG> for sake of clarity.

The elevator control unit <NUM> may be a local elevator control unit, i.e. the elevator control unit <NUM> may be located on-site, i.e. at the elevator system <NUM>. The local elevator control unit <NUM> may be implemented as a part of the elevator control system <NUM> as in the example elevator system <NUM> of <FIG>. The elevator control unit <NUM> implemented as the part of the elevator control system <NUM> may be configured to control one or more operations or functionalities of the elevator system <NUM>. The one or more operations or functionalities of the elevator system <NUM>, which the elevator control unit <NUM> may be configured to control, may for example comprise, but is not limited to, one or more hoisting related operations or functionalities, one or more lighting related operations or functionalities, etc. Alternatively or in addition, the elevator control unit <NUM> may be an external control unit, i.e. the elevator control unit <NUM> may locate off-site, i.e. external to the elevator system <NUM>. The external elevator control unit may be implemented as an external entity to the elevator system <NUM> as illustrated in <FIG> illustrates schematically an example of the elevator system <NUM> in which the elevator control unit <NUM> is the external elevator control unit. The example elevator system <NUM> of <FIG> is otherwise similar to the example elevator system <NUM> of <FIG> described above. In other words, the example elevator system <NUM> of <FIG> may comprise otherwise the same entities as the example elevator system <NUM> of <FIG> described above. The external elevator control unit may be e.g. a cloud server, a service center, or a data center.

<FIG> illustrates an example of at least two wireless communication systems 206a, 206b established for providing a wireless communication connection 206a, 206b, between the elevator control unit <NUM> and the car control unit <NUM>. The car control unit <NUM> and the elevator control unit <NUM> comprise communication means <NUM>, <NUM> to establish at least two wireless communication systems 206a, 206b for providing the wireless communication connection 208a, 208b, between the elevator control unit <NUM> and the car control unit <NUM>. In other words, the car control unit <NUM> comprises communication means <NUM> and the elevator control unit <NUM> comprises communication means <NUM>, which together are configured to establish the at least two wireless communication systems 206a, 206b for providing the wireless communication connection 206a, 206b, between the elevator control unit <NUM> and the car control unit <NUM>. The communication means <NUM> of the car control unit <NUM> may comprise one or more communication devices 210a, 210b, e.g. at least one radio transceiver, at least one antenna, etc., for each of the at least two wireless communication systems 206a, 206b. Similarly, the communication means <NUM> of the elevator control unit <NUM> may comprise corresponding one or more communication devices 212a, 212b for each of the at least two wireless communication systems 206a, 206b. The one or more communication devices 210a, 210b, 212a, 212b may depend on a communication technology used for each wireless communication system 206a, 206b. In the example of <FIG> two wireless communication systems 206a, 206b, e.g. a first wireless communication system 206a and a second wireless communication system 206b, are illustrated, but the three dots in <FIG> depict that there may also be established more than two wireless communication systems 206a, 206b. The wireless communication connection 208a, 208b, between the elevator control unit <NUM> and the car control unit <NUM> enables data exchange, i.e. communication, between the elevator control unit <NUM> and the car control unit <NUM>. In other words, the elevator control unit <NUM> may provide data to the car control unit <NUM> via the wireless communication connection 208a, 208b and/or the car control unit <NUM> may provide data to the elevator control unit <NUM> via the wireless communication connection 208a, 208b. The data may comprise any data regarding to the elevator system <NUM>. The data regarding to the elevator system <NUM> may comprise for example, but not limited to, movement data of the elevator car <NUM>, any safety related data, and/or control data, etc..

The at least two wireless communication systems 206a, 206b may differ from each other by a communication technology. In other words, each wireless communication system 206a, 206b of the at least two wireless communication systems 206a, 206b may be based on a different communication technology than the other wireless communication systems 206a, 206b. For example, in case of two wireless communication systems 206a, 206b, the first wireless communication system 206a may be based on a first communication technology and the second wireless communication system 206b may be based on a second communication technology. The different communication technologies of the at least two wireless communication systems 206a, 206b may comprise at least two of the following communication technologies: a point-to-point microwave link, <NUM>, a free space optical communication technology, Bluetooth (BT), Zigbee, so that each wireless communication system 206a, 206b is based on a different communication technology than the other wireless communication systems 206a, 206b. According to a non-limiting example, in case of two communication systems 206a, 206b, the first wireless communication system 206a may be based e.g. on <NUM> and the second wireless communication system 206b may be based on e.g. the point-to-point microwave link.

Alternatively or in addition, the at least two wireless communication systems 206a, 206b may differ from each other by at least one of the following: a frequency band, a modulation technique, a power level, an antenna type, and/or antenna properties. According to an example, all the at least two wireless communication systems 206a, 206b may be based on the same communication technology, but differ from each other by at least one of the following: a frequency band, a modulation technique, a power level, an antenna type, and/or antenna properties. According to another example, each of the at least two communication systems 206a, 206b may be based on different communication technologies and further differ from each other by at least one of a frequency band, a modulation technique, a power level, an antenna type, and antenna properties. According to a non-limiting example, in case of two communication systems 206a, 206b, both communication systems 206a, 206b may be based e.g. on the point-to-point microwave link, but the first wireless communication system 206a may use e.g. different modulation technique, different power level and/or have different antenna type, than the second wireless communication system 206b.

<FIG> illustrates an example of a method for selecting the wireless communication system 206a, 206b for providing the wireless communication connection 208a, 208b between the elevator control unit <NUM> and the car control unit <NUM>. At an initial starting situation, one of the at least two wireless communication systems 206a, 206b may be used to provide the wireless communication connection 208a, 208b between the elevator control unit <NUM> and the car control unit <NUM>.

At the step <NUM>, the elevator control unit <NUM> obtains selection data representing at least one selection parameter. The at least one selection parameter comprises at least one elevator related selection parameter and/or at least one wireless communication system related selection parameter. The elevator control unit <NUM> may obtain the selection data continuously. The continuous obtaining the selection data enables that the elevator control unit <NUM> is continuously able to respond to one or more changes detected in the obtained selection data, which in turn enables that the elevator control unit <NUM> may continuously select the most appropriate wireless communication system 206a, 206b for providing the wireless communication connection 208a, 208b between the elevator control unit <NUM> and the car control unit <NUM> as will be described. The at least one elevator related selection parameter may comprise at least one of the following: a location of the elevator car inside the elevator shaft, a speed of the elevator car, and/or a sway of a suspension device of the elevator car <NUM>. The sway of the suspension device, e.g. a rope or a belt, may block a line of sight of the wireless communication connection 208a, 208b. The at least one wireless communication system related selection parameter may comprise detected interference in the wireless communication system 206a, 206b. The elevator control unit <NUM> may obtain the selection data representing the at least one elevator related selection parameter for example from the elevator system <NUM> and/or from one or more sensor devices arranged to the elevator system <NUM> and configured to provide the sensor data. The elevator control unit <NUM> may obtain the selection data representing the at least one wireless communication system related selection parameter for example by characterizing and/or monitoring network traffic in the at least two wireless communication systems 206a, 206b.

At the step <NUM>, the elevator control unit <NUM> selects based on the obtained selection data the most appropriate wireless communication system 206a, 206b from amongst the at least two wireless communication systems 206a, 206b at each point of time to be used to provide the wireless communication connection 208a, 208b between the elevator control unit <NUM> and the car control unit <NUM> at a step <NUM>. In other words, the elevator control unit <NUM> selects based on the obtained selection data the most appropriate wireless communication system 206a, 206b from amongst the at least two wireless communication systems 206a, 206b at each point of time, i.e. at each point of time when the selection is performed. This enables that the most appropriate wireless communication system 206a, 206b at each point of time may be selected substantially in real-time. Alternatively or in addition, this enables that a reliable wireless communication connection 208a, 208b between the elevator control unit <NUM> and the car control unit <NUM> may be constantly provided. For example, at a certain point of time depending on the at least one selection parameter, one of the at least two wireless communication systems 206a, 206b may be the most appropriate, i.e. more appropriate than the other wireless communication systems 206a, 206b, and at any other point of time some other wireless communication system 206a, 206b may be the most appropriate. The at least one selection parameter and/or a change of the at least one selection parameter, may affect the wireless communication connection 208a, 208b of each wireless communication system 206a, 206b in different ways. In other words, depending on the selection parameter and the point of time at least one of the at least two wireless communication systems 206a, 206b may be the most appropriate wireless communication system. With the term "most appropriate wireless communication system" is meant throughout this application a wireless communication system 206a, 206b having the most appropriate one or more operating parameters for the wireless communication connection 208a, 208b between the elevator control unit <NUM> and the car control unit <NUM>. The one or more operating parameters may for example comprise, but are not limited to, signal strength, signal quality, capability to transfer required amount of data, and/or capability to transfer required type of data. In other words, the most appropriate wireless communication system 206a, 206b at a certain point of time may have for example, but not limited to, the most appropriate signal strength, signal quality, capability to transfer required amount of data (e.g. large amount of data), and/or capability to transfer required type of data, at said certain point of time. Depending on the operating parameter, the most appropriate may be for example the highest, the best, and/or the largest, etc.. For example, some of the at least two wireless communication systems 208a, 208b may be more appropriate, i.e. more suitable, for short range wireless communication and some other of the at least two wireless communication systems 208a, 208b may be more tolerant against interferences. The reliability of each wireless communication system 206a, 206b may vary (e.g. be reduced or improved) depending on the at least one selection parameter and/or on a change of the at least one selection parameter. According to an example, change in a communication distance, i.e. in the location of the elevator car <NUM> inside the elevator shaft <NUM>, may reduce the reliability of one or more of the at least two wireless communication systems 206a, 206b, and improve the reliability of other one or more of the at least two wireless communication systems 206a, 206b. According to another example, interferences may reduce reliability of one or more of the at least two wireless communication systems 206a, 206b. According to yet another example, the sway of the suspension device of the elevator car <NUM> may reduce the reliability of one or more of the at least two wireless communication systems 206a, 206b. The elevator control unit <NUM> may obtain the one or more operating parameters for example by characterizing and/or monitoring network traffic in the at least two wireless communication systems 206a, 206b.

According to an example, when the car control unit <NUM> and the elevator car control unit <NUM> are substantially close to each other, e.g. when the elevator car <NUM> locates e.g. close to a top of the elevator shaft <NUM> and the elevator control unit <NUM> locates e.g. inside the machine room that locates at the top of the elevator shaft <NUM>, the most appropriate wireless communication system 206a, 206b may be a wireless communication system using lower power level and/or less directional antenna. According to another example, when the car control unit <NUM> and the elevator car control unit <NUM> are far away from each other, e.g. when the elevator car <NUM> locates e.g. close to a pit of the elevator shaft <NUM> and the elevator control unit <NUM> locates e.g. inside the machine room that locates at the top of the elevator shaft <NUM>, the most appropriate wireless communication system 206a, 206b may be a wireless communication system using higher power level, and/or more directional antenna. In these examples, the at least one selection parameter comprises at least the location of the elevator car <NUM> inside the elevator shaft <NUM>. The location of the elevator car <NUM> inside the elevator shaft <NUM> effects on the communication distance between the elevator control unit <NUM> and the elevator car control unit <NUM>.

According to another example, when sway of the suspension device of the elevator car <NUM> is detected to block the line of sight, the most appropriate wireless communication system 206a, 206b may be a wireless communication system that operates without the line of sight. In this example, the at least one selection parameter comprises at least the sway of the suspension device of the elevator car <NUM>.

According to another example, when interference (e.g. radio frequency interference (RFI)) is detected in the wireless communication system 206a, 206b currently used, the most appropriate wireless communication system 206a, 106b may be a wireless communication system which uses frequency hopping. In this example, the at least one selection parameter comprises at least detected interference in the wireless communication system.

According to an example, the most appropriate wireless communication system 206a, 206b for at least one of the at least one selection parameter or for each of the at least one selection parameter may be predefined. In other words, the elevator control unit <NUM> may predefine a certain wireless communication system 206a, 206b to be the most appropriate for at least one of the at least one selection parameter or for each of the at least one selection parameter. This means that the at least one selection parameter may be predefined, i.e. the selection may be based on at least one predefined selection parameter. The elevator control unit <NUM> may for example use for the predefinition historical data of the selection data and/or the one or more operating parameters of the at least two wireless communication systems 206a, 206b; statical data of the selection data and/or the one or more operating parameters of the at least two wireless communication systems 206a, 206b, and/or data learned by using e.g. machine learning algorithms. According to an example, if the at least one selection parameter is the location of the elevator car <NUM> inside the elevator shaft <NUM>, the elevator control unit <NUM> may predefine that a certain wireless communication system 206a, 206b is used when the elevator car <NUM> locates at certain predefined location inside the elevator shaft <NUM>. For example, the elevator control unit <NUM> may predefine that the first wireless communication system 206a may be selected, when the elevator car <NUM> locates at the top floor. Alternatively, the most appropriate wireless communication system for at least one of the at least one selection parameter or for each of the at least one selection parameter may be defined dynamically on a need-basis. In other words, the elevator control unit <NUM> may dynamically on the need-basis define the most appropriate wireless communication system 206a, 206b for at least one of the at least one selection parameter or for each of the at least one selection parameter. This means that the at least one selection parameter may be defined dynamically on a need-basis, i.e. the selection may be based on at least one dynamically defined selection parameter.

According to an example, alternatively or in addition, the one or more selection parameters may be prioritized for the selection of the most appropriate wireless communication system 206a, 206b. The elevator control unit <NUM> may select the most appropriate wireless communication system 206a, 206b based on the one or more selection parameters having highest priority. In other words, one or more of the selection parameters may have a higher importance in the selection of the most appropriate wireless communication system 206a, 206b at the step <NUM>.

As discussed above, at the step <NUM>, i.e. after selecting the most appropriate wireless communication system 206a, 206b at the step <NUM> and during the use of the selected wireless communication system 206a, 206b for providing the wires communication connection 208a, 208b between the elevator control unit <NUM> and the car control unit <NUM>, the elevator control unit <NUM> may continue obtaining the selection data.

According to an example, if the obtained selection data indicates that another wireless communication system 206a, 206b is the most appropriate at a later point of time, i.e. the elevator control unit <NUM> detects at a step <NUM> based on the obtained selection data that another wireless communication system 206a, 206b is the most appropriate at a later point of time, the elevator control unit <NUM> may select at a step <NUM> said another wireless communication system 206a, 206b from amongst the at least two wireless communication systems 206a, 206b to be used to provide the wireless communication connection 208a, 208b between the elevator control unit <NUM> and the car control unit <NUM>. These steps are illustrated as the optional steps <NUM> and <NUM> in the example of <FIG>. Alternatively, if the obtained selection data indicates that the previously selected wireless communication system 206a, 206b, i.e. the wireless communication system 206a, 206b currently used to provide the wireless communication connection 208a, 208b between the elevator control unit <NUM> and the car control unit <NUM>, is still the most appropriate at said later point of time, the use of the previously selected wireless communication system 206a, 206b is continued for providing the wireless communication connection 208a, 208b between the elevator control unit <NUM> and the car control unit <NUM>, and the elevator control unit <NUM> continues to obtain the selection data.

Next an example for selecting the wireless communication system 206a, 206b by using two wireless communication systems 206a, 206b, e.g. illustrated in <FIG>, i.e. the first wireless communication system 206a and the second wireless communication system 206b. In this non-limiting example, the at least one selection parameter is the location of the elevator car <NUM> inside the elevator shaft <NUM> and the most appropriate one or more operating parameters for the wireless communication connection 208a, 208b between the elevator control unit <NUM> and the car control unit <NUM> is the highest signal quality. However, the invention is not limited to these and any other at least one selection parameter and/or one or more operating parameters may be used. As an initial assumption, the first wireless communication system 206a is used to provide the wireless communication connection 208a between the elevator control unit <NUM> and the car control unit <NUM> at a starting situation, for example because at the starting situation, the first wireless communication system 206a has the highest signal strength. However, also the second communication system 206b could be used to provide the wireless communication connection 208b between the elevator control unit <NUM> and the car control unit <NUM> at the starting situation. The elevator control unit <NUM> obtains continuously the selection data representing, in this example, the location of the elevator car <NUM> inside the elevator shaft <NUM>, when the elevator car <NUM> is moving along the elevator shaft <NUM>, e.g. from the top floor to the bottom floor, and at a certain point of time, the elevator control unit <NUM> detects based on the obtained selection data that the location of the elevator car <NUM> is such that the second wireless communication system 206b has the highest signal strength. In other words, the elevator control unit <NUM> detects that the second wireless communication system <NUM> is the most appropriate communication system based on the obtained selection data at said certain point of time. In response to the detection that the second wireless communication system 206b is the most appropriate wireless communication system, the elevator control unit <NUM> selects the second wireless communication system 206b to be used to provide the wireless communication connection 208b between the elevator control unit <NUM> and the car control unit <NUM>. The second wireless communication system 206b is used to provide the wireless communication connection 208b between the elevator control unit <NUM> and the car control unit <NUM> after the selection and the elevator control unit <NUM> may continue obtaining the selection data.

<FIG> schematically illustrates an example of components of the elevator control unit <NUM>. The elevator control unit <NUM> may comprise a processing unit <NUM> comprising one or more processors, a memory unit <NUM> comprising one or more memories, a communication interface unit <NUM>, and possibly a user interface (UI) unit <NUM>. The mentioned elements may be communicatively coupled to each other with e.g. an internal bus. The memory unit <NUM> may store and maintain portions of a computer program (code) <NUM> and any other data, e.g. the obtained selection data. The computer program <NUM> may comprise instructions which, when the computer program <NUM> is executed by the processing unit <NUM> of the elevator control unit <NUM> may cause the processing unit <NUM>, and thus the elevator control unit <NUM> to carry out desired tasks, e.g. at least some of the method steps described above. The processing unit <NUM> may thus be arranged to access the memory unit <NUM> and retrieve and store any information therefrom and thereto. For sake of clarity, the processor herein refers to any unit suitable for processing information and control the operation of the elevator control unit <NUM>, among other tasks. The operations may also be implemented with a microcontroller solution with embedded software. Similarly, the memory unit <NUM> is not limited to a certain type of memory only, but any memory type suitable for storing the described pieces of information may be applied in the context of the present invention. The communication interface unit <NUM> provides an interface for communication with any external unit, e.g. the car control unit <NUM>, one or more databases, and/or any other external unit. The communication interface unit <NUM> may comprise the above-described communication means <NUM> of the elevator control unit <NUM>. The communication means <NUM> of the elevator control unit <NUM> may comprise one or more communication devices 210a, 210b, e.g. at least one radio transceiver, at least one antenna, etc., for each of the at least two wireless communication systems 206a, 206b as described above. The communication interface unit <NUM> may further comprise one or more other communication devices, for communication with any other units than the car control unit <NUM>. The one or more user interface units <NUM> may comprise one or more input/output (I/O) devices, such as buttons, keyboard, touch screen, microphone, loudspeaker, display and so on, for receiving user input and outputting information. The computer program <NUM> may be a computer program product that may be comprised in a tangible non-volatile (non-transitory) computer-readable medium bearing the computer program code <NUM> embodied therein for use with a computer, i.e. the elevator control unit <NUM>.

<FIG> schematically illustrates an example of components of the car control unit <NUM>. The car control unit <NUM> may comprise a processing unit <NUM> comprising one or more processors, a memory unit <NUM> comprising one or more memories, a communication interface unit <NUM>, and possibly a user interface (UI) unit <NUM>. The mentioned elements may be communicatively coupled to each other with e.g. an internal bus. The memory unit <NUM> may store and maintain portions of a computer program (code) <NUM> and any other data, e.g. the obtained selection data. The computer program <NUM> may comprise instructions which, when the computer program <NUM> is executed by the processing unit <NUM> of the car control unit <NUM> may cause the processing unit <NUM>, and thus the car control unit <NUM> to carry out desired tasks, e.g. at least some of the operations of the car control unit <NUM> as described above. The processing unit <NUM> may thus be arranged to access the memory unit <NUM> and retrieve and store any information therefrom and thereto. For sake of clarity, the processor herein refers to any unit suitable for processing information and control the operation of the car control unit <NUM>, among other tasks. The operations may also be implemented with a microcontroller solution with embedded software. Similarly, the memory unit <NUM> is not limited to a certain type of memory only, but any memory type suitable for storing the described pieces of information may be applied in the context of the present invention. The communication interface unit <NUM> provides an interface for communication with any external unit, e.g. the elevator control unit <NUM>, one or more databases, and/or any other external unit. The communication interface unit <NUM> may comprise the above-described communication means <NUM> of the car control unit <NUM>. The communication means <NUM> of the car control unit <NUM> may comprise one or more communication devices 212a, 212b, e.g. at least one radio transceiver, at least one antenna, etc., for each of the at least two wireless communication systems 206a, 206b as described above. The communication interface unit <NUM> may further comprise one or more other communication devices, for communication with any other units than the elevator control unit <NUM>. The one or more user interface units <NUM> may comprise one or more input/output (I/O) devices, such as buttons, keyboard, touch screen, microphone, loudspeaker, display and so on, for receiving user input and outputting information. The computer program <NUM> may be a computer program product that may be comprised in a tangible non-volatile (non-transitory) computer-readable medium bearing the computer program code <NUM> embodied therein for use with a computer, i.e. the car control unit <NUM>.

The elevator system <NUM> and the method as described above improve the reliability of the wireless communication connection of the elevator system <NUM>. The elevator system <NUM> and the method as described above reduce temporary breaks in the wireless communication connection, and thus also emergency stops of the elevator system may be reduced.

Claim 1:
An elevator system (<NUM>) for selecting a wireless communication system (206a, 206b), wherein the elevator system (<NUM>) comprises:
an elevator car (<NUM>) arranged to travel along an elevator shaft (<NUM>),
a car control unit (<NUM>) arranged to the elevator car (<NUM>), and
an elevator control unit (<NUM>),
wherein the car control unit (<NUM>) and the elevator control unit (<NUM>) comprise communication means (<NUM>, <NUM>) to establish at least two wireless communication systems (206a, 206b) for providing wireless communication (208a, 208b) between the elevator control unit (<NUM>) and the car control unit (<NUM>), and
characterized in that the elevator control unit (<NUM>) is configured to:
obtain selection data representing at least one selection parameter, wherein the at least one selection parameter comprises at least one elevator related selection parameter, wherein the at least one elevator related selection parameter comprises at least one of the following: a location of the elevator car (<NUM>) inside the elevator shaft (<NUM>), a speed of the elevator car (<NUM>), and/or a sway of a suspension device of the elevator car (<NUM>), and
select based on the obtained selection data the most appropriate wireless communication system (206a, 206b) from amongst the at least two wireless communication systems (206a, 206b) at each point of time to be used to provide the wireless communication connection (208a, 208b) between the elevator control unit (<NUM>) and the car control unit (<NUM>).