A method in a system comprising a device and a controller configured to control operation of the device

Abstract

A method in a system, comprising a device and a controller communicatively coupled or couplable with the device via at least one wireless channel, is disclosed, wherein the controller may be configured to control operation of the device. The controller transmits a command message in the wireless channel, with the command message including a command to control operation of the device and a command message identifier identifying the command message. The command message includes N sub-messages transmitted successively over a first period of time, and each of the N sub-messages includes: the command, the command message identifier, and an incremental sub-message identifier. The incremental sub-message identifiers for the respective ones of the N sub-messages are different relatively to each other and indicate the relative temporal positions of the N sub-messages in the first period of time. The device, for at least one of the N sub-messages, transmits an acknowledgement message after a waiting period of time has elapsed following the receipt of the sub-message.

Description

[0001] A method in a system comprising a device and a controller configured to control operation of the device

[0002] TECHNICAL FIELD

[0003] The present invention relates to a method in a system comprising a controller and a device communicatively coupled or couplable with the controller via at least one wireless channel, wherein the method is for communication between the controller and the device. The present invention further relates to the system.

[0004] BACKGROUND

[0005] In lighting systems, a controller may be configured to control operation of one or more lighting devices in the lighting system, wherein wireless local area network (WLAN) channels may be used for communication of control signaling from the controller to the lighting device(s). WLAN channels may be accessed using the IEEE (Institute of Electrical and Electronics Engineers) 802.11 protocols, for example. The IEEE 802.11 standard provides several distinct radio frequency bands for use in Wi-Fi communications, such as, for example, the 2.4 GHz range, with each range being divided into several channels. For example, in the 2.4 GHz range, fourteen channels are designated. A controller in a lighting system utilizing WLAN channels may however not ‘know’ which particular channel of the several channels a lighting device in the lighting system uses for communication. Therefore, for example in the 2.4 GHz range, the controller may need to transmit control signaling in each of the designated channels. Also, in order to ensure a relatively high chance of successfully transmitting the control signaling (e.g., packets) to the lighting device, the lighting device may need to employ relatively long wake-up periods of time, in which the lighting device awaits (i.e., is listening for) control signaling from the controller, between sleep periods of time, in which the lighting device does not await control signaling from the controller. In view of the above, in order to ensure effective communication of control signaling from the controller to the lighting device(s), the power consumption of the controller and the lighting device(s) may become relatively high.

[0006] US6496481B1 discloses a transport protocol that meets the requirements and performance for multimedia data transfer in a wireless link includes a transmitting / sending station and a receiving station. This scheme uses a large transmission window for sending / receiving a burst of time-sensitive data and, within this window, several smaller observation windows are used for dynamic error retransmission. There is a time limitation on each retransmission such that the burst of data can be received in a timely manner, and thus trading some packet losses (still in an acceptable range) for delay and throughput performance.

[0007] US2006035589A1 discloses a method for allowing delayed acknowledgement in a local wireless transceiver. In this method the local transceiver receives n data frames from a remote wireless transceiver, each data frame including a set of acknowledgement policy bits, which indicate a desired acknowledgement policy for the respective data frame. The first (n-1) data frames indicate an acknowledgement policy of delayed acknowledgement with no acknowledgement requested, while the final data frame indicates an acknowledgement policy of delayed acknowledgement with acknowledgement requested. In response to the acknowledgement policy of the last data frame, the local transceiver sends a delayed acknowledgement response frame to the remote wireless transceiver.

[0008] US2019018376A1 discloses wireless devices operable at intermediate wireless at ranges of thousands of meters, utilizing packets that include a preamble and a data payload. A digital spread-spectrum frequency hopping rotation is used, wherein packet transmissions rotate through frequency sequences. A spectrum-impact-smoothed channel set is fashioned using sequences that each specify a unique preamble frequency relative to the other sequences and channels. The set is traversed as packets are transmitted, thereby distributing the focused radio-frequency emission impact of packets having long preambles over time. Packet acknowledgments are deferred until a group of packets in a stream has been exchanged.

[0009] SUMMARY

[0010] In view of the above, a concern of the present invention is to provide means for providing effective communication of control signaling from a controller to a device controlled or controllable by the controller while keeping the power consumption of the controller and the device relatively low. The device may for example comprise a lighting device. The controller may for example comprise a remote control, or a wall switch.

[0011] According to a first aspect of the present invention, a method is provided, which method is in a system comprising a controller and a device communicatively coupled or couplable with the controller via at least one wireless channel. The controller may be configured to control operation of the device and may hence be communicatively couplable (or coupled) with the device via the at least one wireless channel. The controller has a memory in which a previously determined channel identifier of the at least one wireless channel for communication between the controller and the device is stored. The method comprises the controller transmitting a command message in the wireless channel corresponding to the channel identifier stored in the memory of the controller. The command message includes a command to control operation of the device and a command message identifier identifying the command message. The command message includes N submessages which are transmitted successively over a first period of time, wherein N > 1. Each of the N sub-messages includes: the command, the command message identifier, and an incremental sub-message identifier. The incremental sub-message identifiers for the respective ones of the N sub-messages are different relatively to each other and indicate the relative temporal positions of the N sub-messages in the first period of time. The device obtains, or has previously obtained, indications of N and the selected first period of time. The device, for at least one of the N sub-messages, transmits, an acknowledgement message after a waiting period of time has elapsed following the receipt of the sub-message. The device determines the waiting period of time based on at least N, the first period of time and the incremental sub-message identifier of the sub-message. The controller, upon receipt of the acknowledgement message, enters a power saving state. In the power saving state (or power saving mode) of the controller, the controller may turn off at least one of its transmission and reception communication capabilities.

[0012] According to a second aspect of the present invention, a system is provided. The system comprises a controller and a device communicatively coupled or couplable with the controller via at least one wireless channel. The controller may be configured to control operation of the device and may hence be communicatively couplable with the device via the at least one wireless channel. The controller has a memory in which a previously determined channel identifier of the wireless channel of the at least one wireless channel for communication between the controller and the device is stored. The controller is configured to transmit a command message in the wireless channel corresponding to the channel identifier stored in the memory of the controller. The command message includes a command to control operation of the device and a command message identifier identifying the command message. The command message includes N sub-messages which are transmitted successively over a first period of time, wherein N > 1. Each of the N sub-messages includes: the command, the command message identifier, and an incremental sub-message identifier. The incremental sub-message identifiers for the respective ones of the N sub-messages are different relatively to each other and indicate the relative temporal positions of the N submessages in the first period of time. The device is configured to obtain, or has previously obtained, indications of N and the selected first period of time. The device is configured to, for at least one of the N sub-messages, transmit an acknowledgement message after a waiting period of time has elapsed following the receipt of the sub-message. The device determines the waiting period of time based on at least N, the first period of time and the incremental sub-message identifier of the sub-message. The controller is configured to, upon receipt of the acknowledgement message, enter a power saving state. In the power saving state of the controller, the controller may turn off at least one of its transmission and reception communication capabilities.

[0013] In accordance with the first and second aspects of the present invention, the command message can be transmitted in one wireless channel, by which the power consumption of the controller may become less as compared to a solution wherein the controller would not ‘know’ which particular channel of several channels the device uses for communication and the controller therefore would need to transmit the command message in each of the several channels, such as, for example, each of the fourteen designated channels in the 2.4 GHz frequency range for use in Wi-Fi communications. In this regard, by the acknowledgement message which may be sent by the device, it can be confirmed that the wireless channel corresponding to the channel identifier stored in the memory of the controller can still be used for communication between the device and the controller. As mentioned, for each sub-message of the N sub-messages that is received by the device, and if device has not yet received any sub-message including the command message identifier in the sub-message, the device may be configured to transmit, in the wireless channel corresponding to the channel identifier, an acknowledgement message after a waiting period of time has elapsed following the receipt of the sub-message.

[0014] Further in accordance with the first and second aspects of the present invention, the controller is configured to, if the controller receives an acknowledgement message, upon receipt of the acknowledgement message enter a power saving state, in which the controller may turn off at least one of its transmission and reception communication capabilities. By entering the power saving state (e.g., immediately) after having received an acknowledgement message, the power consumption of the controller may be kept relatively low. The said power saving state may in alternative be referred to as a power saving mode or an idle state or mode. In such a power saving or idle state or mode, the controller may turn off at least its transmission and reception communication capabilities. The controller may include a power source (e.g., a battery), and in the power saving or idle state or mode, the controller may shut down power from the power source to the elements of the controller which enable the transmission and reception communication capabilities of the controller (e.g., including one or more radio frequency antennas). Upon having entered a power saving or idle state or mode, the controller may not leave the power saving or idle state or mode until another command message is to be transmitted. The controller may include a user interface configured to receive user input. The controller may leave the power saving or idle state or mode responsive to user input being received via the user interface indicating a command to control operation of the device.

[0015] By the command message including N (with N > 1) sub-messages which are transmitted successively over the first period of time and with each of the N sub-messages including the command, the command is repeatedly transmitted, whereby a relatively high chance of successfully transmitting the command message to the device can be achieved.

[0016] The channel identifier stored in the memory of the controller may have been previously determined by the carrying out of a pairing process to establish a relationship between the controller and the device for wireless communications, e.g., via the at least one wireless channel. The pairing process may for example be carried out in an out of band way, e.g., by means of Bluetooth low energy pairing. The pairing process may be a pairing process which as such is known in the art. The memory of the controller may for example comprise a Flash memory.

[0017] As mentioned, the incremental sub-message identifiers for the respective ones of the N sub-messages indicate the relative temporal positions of the N sub-messages in the first period of time. In other words, for each sub-message, the incremental sub-message identifier indicates the temporal position of the sub-message in the succession of submessages over the selected period of time in relation to the other sub-messages.

[0018] If the device receives a (e.g., second) sub-message which includes a command message identifier that is the same as the command message identifier included in a previously received (e.g., first) sub-message, the (e.g., second) sub-message may be discarded by the device.

[0019] As mentioned, the device is configured to obtain, or has previously obtained, indications of N and the selected first period of time. This may entail that N and the selected first period of time are “known” by the device, e.g., by N and the selected first period of time being predefined or preconfigured in the device (e.g., having been previously stored in a memory of the device). In alternative or in addition, N and the selected first period of time may have been signaled by the controller to the device. For example, N and the selected first period of time may be part of and / or defined by an upper layer protocol.

[0020] As mentioned, the device may (e.g., be configured to), for at least one of the N sub-messages, transmit an acknowledgement message after a waiting period of time has elapsed following the receipt of the sub-message. Possibly, this may comprise the device (e.g., being configured to), for each sub-message of the N sub-messages that is received by the device, and if device has not yet received any sub-message including the command message identifier in the sub-message, transmitting an acknowledgement message after a waiting period of time has elapsed following the receipt of the sub-message.

[0021] By the device transmitting an acknowledgement message for a sub-message that is received by the device not until after the waiting period of time has elapsed following the receipt of the sub-message, and with the waiting period of time being determined based on at least N, the first period of time and the incremental sub-message identifier of the submessage, the risk of acknowledgement messages originating from respective ones of several devices with which the controller may be communicatively coupled or couplable arriving at the controller at the same time or substantially at the same time may be reduced or even avoided. By such a configuration, an efficient time-sharing of the wireless channel may be achieved, which may increase the efficiency in communication between the device and the controller and result in only a small number of errors or even no errors in transmissions between the device and the controller. For example, the device may determine the waiting period of time based on determining (N - IDinCT)Ti / N, where IDinCTis the incremental submessage identifier of the sub-message and is an integer IDinCT= 1, . . ., N for the respective ones of the N successive sub-messages, and Ti is the duration of the first period of time. The device may determine the waiting period of time further based on a time delay Ta, e.g., a random time delay Ta, such that the waiting period of time is determined as

[0022] (N - IDinCT)Ti / N + Ta, wherein Ta > 0 s. The time delay Ta may be based on randomly generated value in a predetermined range of values.

[0023] For each command message, the command message identifier may uniquely identify the command message from / in relation to any other command message(s) previously transmitted by the controller and any following command message(s) transmitted by the controller.

[0024] In the context of the present application, any reference herein to the “first period of time” may relate to the start time of the first period of time and / or the duration of the first period of time. The device may be configured to periodically be in a state in which transmission and reception communication capabilities are turned on while at other times be in a state in which at least the transmission and reception communication capabilities of the device are turned off. During the first period of time there may be at least one period of time during which transmission and reception communication capabilities of the device are turned on. The periods of time during which transmission and reception communication capabilities of the device are turned on and the periods of time therebetween during which transmission and reception communication capabilities of the device are turned off may have such durations in relation to the first period of time, or vice versa, such that during the first period of time there is at least one period of time during which transmission and reception communication capabilities of the device are turned on. By such configurations, it may be ensured that for each command message transmitted by the controller (as N sub-messages which are transmitted successively over the first period of time), at least one of the N submessages is received by the device.

[0025] The state in which transmission and reception communication capabilities are turned on may be referred to as a wake-up state or mode, in which the device is in a state or mode in which it awaits (in other words, is listening for) a (e.g., command) message from the controller. The state in which at least the transmission and reception communication capabilities of the device are turned off may be referred to as a sleep state or mode, in which the device is in a state or mode in which it does not await (in other words, is not listening for) a (e.g., command) message from the controller.

[0026] For example, the periods of time during which transmission and reception communication capabilities of the device are turned on and the periods of time therebetween during which transmission and reception communication capabilities of the device are turned off may be alternatingly occurring. The periods of time during which transmission and reception communication capabilities of the device are turned on may be (e.g., about) 10 ms and the periods of time therebetween during which transmission and reception communication capabilities of the device are turned off may be (e.g., about) 90 ms. Thus, in each 100 ms time period, the device may be in a wake-up state or mode for (e.g., about) 10 ms and in a sleep state or mode for (e.g., about) 90 ms. By such a configuration, the power consumption of the device may be kept relatively low.

[0027] The acknowledgement message for a sub-message transmitted by the device may include the command message identifier included in the sub-message, and possibly also the channel identifier. The device may be communicatively couplable with the controller via a plurality of wireless channels including the at least one wireless channel. If the controller, after the first period of time has elapsed and, following the elapse of a second period of time, has not yet received any acknowledgement message, the controller may re-transmit the command message in the wireless channel corresponding to the channel identifier and / or transmit the command message in the other one(s) of the plurality of wireless channels. Such re-transmission of the command message in the wireless channel corresponding to the channel identifier and / or transmission of the command message in the other one(s) of the plurality of wireless channels may be carried out only in case the controller, after the first period of time has elapsed and, following the elapse of a second period of time, has not yet received any acknowledgement message. The second period of time may for example have duration of (e.g., about) 200 ms.

[0028] If the controller subsequently receives an acknowledgement message which includes a channel identifier different from the channel identifier stored in the memory of the controller, the controller may replace the channel identifier stored in the memory of the controller with the channel identifier included in the acknowledgement message. Thereby, in case the communication between the device and the controller has been switched to another one of the plurality of wireless channels, the channel identifier stored in the memory of the controller may be updated accordingly, so that any following transmission of a command message (as per the first and second aspects of the present invention) by the controller to the device takes place on that other wireless channel.

[0029] The device may be communicatively couplable with the controller via at least one wireless channel of a wireless local area network (WLAN), which may be based on the IEEE (Institute of Electrical and Electronics Engineers) 802.11 protocols, for example.

[0030] The device may comprise or be comprised in a lighting device configured to controllably emit light. The command included in the command message may be a command to control emission of light from the lighting device

[0031] The controller may be (e.g., further) communicatively coupled or couplable with at least one other device, and may be (e.g., further) configured to control operation of the at least one other device. The at least one other device may be communicatively couplable with the controller via the at least one wireless channel. The transmission by the controller of the command message in the wireless channel corresponding to the channel identifier stored in the memory of the controller may comprise the controller broadcasting the command message in the wireless channel corresponding to the channel identifier stored in the memory of the controller. The command included in the command message may be to control operation of each of the said devices, wherein each of the said devices receiving the command message after receipt of the command operates according to the command included in the command message. The broadcasting may be such that the command is executed at the same time, or substantially at the same time, by each of the said devices.

[0032] According to a third aspect of the present invention, a controller in a system according to the second aspect of the present invention is provided.

[0033] According to a fourth aspect of the present invention, a device in a system according to the second aspect of the present invention is provided.

[0034] As mentioned, the device is communicatively coupled or couplable with the controller via at least one wireless channel. To that end, each or any device and / or the controller may comprise one more transmit and / or receive elements such as one or more radio frequency antennas in order to provide each or any device and / or the controller with a capability to communicate with, e.g., the controller and the device, respectively. Further, each or any device and / or the controller may comprise one or more processors configured to cooperate with the one more transmit and / or receive elements to perform transmission and reception as described herein as well as to carry out any other operation as described herein. The one or more processors may for example comprise a central processing unit (CPU), a digital signal processor (DSP), one or more microprocessors, an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, or the like.

[0035] Further objects and advantages of the present invention are described in the following by means of exemplifying embodiments. It is noted that the present invention relates to all possible combinations of features recited in the claims. Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the description herein. Those skilled in the art realize that different features of the present invention can be combined to create embodiments other than those described herein.

[0036] BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Exemplifying embodiments of the invention will be described below with reference to the accompanying drawings.

[0038] Fig. l is a schematic view of a system according to an embodiment of the present invention. Fig. 2 is a schematic illustration of a first period of time and a subsequent period of time during which acknowledgement messages may be sent by devices in accordance with an embodiment of the present invention.

[0039] Fig. 3 is a schematic flowchart of a method according to an embodiment of the present invention.

[0040] All the figures are schematic, not necessarily to scale, and generally only show parts which are necessary in order to elucidate embodiments of the present invention, wherein other parts may be omitted or merely suggested.

[0041] DESCRIPTION WITH REFERENCE TO THE DRAWINGS

[0042] The present invention will now be described hereinafter with reference to the accompanying drawings, in which exemplifying embodiments of the present invention are shown. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments of the present invention set forth herein; rather, these embodiments of the present invention are provided by way of example so that this disclosure will convey the scope of the invention to those skilled in the art. In the drawings, identical reference numerals denote the same or similar components having a same or similar function, unless specifically stated otherwise.

[0043] Figure 1 is a schematic view of a system 10 according to an embodiment of the present invention. The system 10 comprises a controller 1 and a device 2 communicatively coupled or couplable with the controller 1.

[0044] The controller 1, which may be configured to control operation of the device 2, is communicatively couplable with the device 2 via at least one wireless channel, schematically indicated at 3. The controller 1 has a memory 4 in which a previously determined channel identifier of the at least one wireless channel 3 for communication between the controller 1 and the device 2 is stored.

[0045] The controller 1 is configured to transmit a command message in the wireless channel 3 corresponding to the channel identifier stored in the memory 4 of the controller 1. The command message includes a command to control operation of the device 2 and a command message identifier identifying the command message. The command message includes N sub-messages transmitted successively over a first period of time, wherein N > 1. Each of the N sub-messages includes: the command, the command message identifier, and an incremental sub-message identifier, wherein the incremental sub-message identifiers for the respective ones of the N sub-messages are different relatively to each other and indicate the relative temporal positions of the N sub-messages in the first period of time.

[0046] The device 2 is configured to obtain, or has previously obtained, indications of N and the selected first period of time.

[0047] The device 2 is configured to, for at least one of the N sub-messages, transmit an acknowledgement message after a waiting period of time has elapsed following the receipt of the sub-message. For example, the device 2 may be configured to, for each sub-message of the N sub-messages that is received by the device 2, and if device 2 has not yet received any sub-message including the command message identifier in the sub-message, transmit (e.g., in the wireless channel 3 corresponding to the channel identifier) an acknowledgement message after a waiting period of time has elapsed following the receipt of the sub-message. The device 2 determines the waiting period of time based on at least N, the first period of time and the incremental sub-message identifier of the sub-message.

[0048] The controller 1 is configured to upon receipt of the acknowledgement message enter a power saving state, in which power saving state the controller 1 may turn off at least one of its transmission and reception communication capabilities.

[0049] Upon having entered that state, the controller 1 may not leave that state until another command message is to be transmitted. The controller 1 may include a user interface 6 configured to receive user input. The controller 1 may leave the said state responsive to user input being received via the user interface 6 indicating a command to control operation of the device 2, based on which another command message may be generated. The command message first referenced in the description referring to Figure 1 may likewise have been generated based on, or responsive to, input being received via the user interface 6 indicating a command to control operation of the device 2. Once the controller 1 leaves the said state, it may thus enter a state in which the controller 1 its transmission and reception communication capabilities are turned on.

[0050] Figure 2 is a schematic illustration of a first period of time T1 and a subsequent period of time T2 during which acknowledgement messages may be sent by devices (such as, e.g., devices configured in accordance with the device 2 as described in the foregoing with reference to Figure 1) in accordance with an embodiment of the present invention. In Figure 2, time is advancing to the right in the figure.

[0051] The dashed rectangles in Figure 2 represent N sub-messages of a command message, including a command to control operation of at least one, some, or each of the devices and a command message identifier identifying the command message, transmitted by a controller (not shown in Figure 2; cf. Figure 1). The controller may be configured in accordance with the controller 1 as described in the foregoing with reference to Figure 1. Thus, the controller may transmit the command message in the wireless channel corresponding to the channel identifier stored in a memory of the controller, as described in the foregoing with reference to Figure 1.

[0052] In the example depicted in Figure 2, N » 1. The N sub-messages are transmitted successively over the first period of time Tl. Each of the N sub-messages includes: the command, the command message identifier, and an incremental sub-message identifier, wherein the incremental sub-message identifiers for the respective ones of the N sub-messages are different relatively to each other and indicate the relative temporal positions of the N sub-messages in the first period of time Tl. Each device may obtain, or may have previously obtained, indications of N and the selected first period of time Tl.

[0053] Each of the three lines 31, 32 and 33 in Figure 2 represents one device, and each line 31, 32, 33 has a baseline and three periodic steps with respect to the baseline. For each line 31, 32, 33, the baseline represents periods of time during which transmission and reception communication capabilities of the respective device are turned off, and the steps represent periods of time during which transmission and reception communication capabilities of the respective device are turned on. The periods of time during which transmission and reception communication capabilities of the device(s) are turned on may be (e.g., about) 10 ms and the periods of time therebetween during which transmission and reception communication capabilities of the device(s) are turned off may be (e.g., about) 90 ms. Thus, in each 100 ms time period, the device may be in a wake-up state or mode for (e.g., about) 10 ms and in a sleep state or mode for (e.g., about) 90 ms.

[0054] In accordance with the embodiment of the present invention illustrated in Figure 2, for each device, during the first period of time Tl there is at least one period of time during which transmission and reception communication capabilities of the device are turned on. For example, for each device, the periods of time during which transmission and reception communication capabilities of the device are turned on and the periods of time therebetween during which transmission and reception communication capabilities of the device are turned off may have such durations in relation to the first period of time Tl, or vice versa, such that during the first period of time Tl there is at least one period of time during which transmission and reception communication capabilities of the device are turned on. As illustrated in Figure 2, in the illustrated example, there are, for each of the devices, during the first period of time T1 two periods of time during which transmission and reception communication capabilities of the device are turned on.

[0055] After the first period of time T1 has elapsed - and once the controller has transmitted the N sub-messages of the command message, the controller may enter a state in which it awaits (i.e., is listening for) acknowledgements from each or any of the devices. As indicated in Figure 2, the controller may be in that state during a certain period of time T2.

[0056] The dotted rectangles at lines 31, 32 and 33, respectively, in Figure 2 represent acknowledgement messages transmitted by the respective devices during periods of time during which transmission and reception communication capabilities of the devices are turned on.

[0057] It may be ensured that no device transmits an acknowledgement during the first period of time T1 when the command message is transmitted by the controller by way of each device employing a waiting period of time which must have elapsed before the device transmits any acknowledgement message. For each device, and for at least one of the N submessages, the device transmits an acknowledgement message after a waiting period of time has elapsed following the receipt of the sub-message. For example, for each device, and for each sub-message of the N sub-messages that is received by the device and if device has not yet received any sub-message including the command message identifier in the sub-message, the device may transmit an acknowledgement message after a waiting period of time has elapsed following the receipt of the sub-message. The device may determine the waiting period of time based on determining (N - IDinCT)Tl / N, where IDinCTis the incremental submessage identifier of the sub-message and is an integer IDinCT= 1, . . ., N for the respective ones of the N successive sub-messages. The device may determine the waiting period of time further based on a time delay Ta such that the waiting period of time is determined as (N - IDinCT)Tl / N + Ta, wherein Ta > 0 s and may be a random time delay and may be based on randomly generated value in a predetermined range of values. The predetermined range of values may for example be > 0 s and < 100 ms, for example.

[0058] Figure 3 is a schematic flowchart of a method 20 according to an embodiment of the present invention. The method 20 is in a system comprising a controller and a device communicatively coupled or couplable with the controller via at least one wireless channel. The controller has a memory in which a previously determined channel identifier of the at least one wireless channel for communication between the controller and the device is stored.

[0059] The method 20 comprises, at 21, the controller transmitting a command message in the wireless channel corresponding to the channel identifier stored in the memory of the controller. The command message includes a command to control operation of the device and a command message identifier identifying the command message. The command message includes N sub-messages transmitted successively over a first period of time, wherein N > 1. Each of the N sub-messages includes: the command, the command message identifier, and an incremental sub-message identifier, wherein the incremental sub-message identifiers for the respective ones of the N sub-messages are different relatively to each other and indicate the relative temporal positions of the N sub-messages in the first period of time. The device obtains, or has previously obtained, indications of N and the selected first period of time.

[0060] At 22, the device, for at least one of the N sub-messages, transmits an acknowledgement message after a waiting period of time has elapsed following the receipt of the sub-message, wherein the device determines the waiting period of time based on at least N, the first period of time and the incremental sub-message identifier of the sub-message.

[0061] At 23, the controller, upon receipt of the acknowledgement message, enters a power saving state, in which power saving state the controller may turn off at least one of its transmission and reception communication capabilities.

[0062] The method 20 may then end.

[0063] In conclusion, a method in a system, comprising a device and a controller communicatively coupled or couplable with the device via at least one wireless channel, is provided. The controller may be configured to control operation of the device. The controller transmits a command message in the wireless channel, with the command message including a command to control operation of the device and a command message identifier identifying the command message. The command message includes N sub-messages transmitted successively over a first period of time, and each of the N sub-messages includes: the command, the command message identifier, and an incremental sub-message identifier. The incremental sub-message identifiers for the respective ones of the N sub-messages are different relatively to each other and indicate the relative temporal positions of the N submessages in the first period of time. The device, for at least one of the N sub-messages, transmits an acknowledgement message after a waiting period of time has elapsed following the receipt of the sub-message.

[0064] While the present invention has been illustrated in the appended drawings and the foregoing description, such illustration is to be considered illustrative or exemplifying and not restrictive; the present invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the appended claims, the word “comprising” does not exclude other elements or steps, and the indefinite article ”a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS:

1. A method (20) in a system (10) comprising a controller (1) and a device (2) communicatively coupled or couplable with the controller via at least one wireless channel (3), wherein the controller has a memory (4) in which a previously determined channel identifier of the at least one wireless channel for communication between the controller and the device is stored, the method comprising: the controller transmitting (21) a command message in the wireless channel corresponding to the channel identifier stored in the memory of the controller, the command message including a command to control operation of the device and a command message identifier identifying the command message, wherein the command message includes N submessages transmitted successively over a first period of time (Tl), wherein N > 1, and wherein each of the N sub-messages includes: the command, the command message identifier, and an incremental sub-message identifier, wherein the incremental sub-message identifiers for the respective ones of the N sub-messages are different relatively to each other and indicate the relative temporal positions of the N sub-messages in the first period of time, wherein the device obtains, or has previously obtained, indications of N and the selected first period of time; the device, for at least one of the N sub-messages, transmitting (22) an acknowledgement message after a waiting period of time has elapsed following the receipt of the sub-message, wherein the device determines the waiting period of time based on at least N, the first period of time and the incremental sub-message identifier of the sub-message; the controller, upon receipt of the acknowledgement message, entering (23) a power saving state.

2. A method according to claim 1, wherein the device is configured to periodically be in a state in which transmission and reception communication capabilities are turned on while at other times be in a state in which at least the transmission and reception communication capabilities of the device are turned off, wherein during the first period of time there is at least one period of time during which transmission and reception communication capabilities of the device are turned on.

3. A method according to any one of claims 1-2, wherein the device determines the waiting period of time based on determining (N - IDinCT)Ti / N, where IDinCTis the incremental sub-message identifier of the sub-message and is an integer IDinCT= 1, . . N for the respective ones of the N successive sub-messages, and Ti is the duration of the first period of time.

4. A method according to claim 3, wherein the device determines the waiting period of time further based on a random time delay Ta such that the waiting period of time is determined as (N - IDinCT)Ti / N + Ta, wherein Ta > 0 s.

5. A method according to any one of claims 1-4, wherein the power saving state is a state in which the controller turns off at least one of its transmission and reception communication capabilities.

6. A method according to any one of claims 1-5, wherein the acknowledgement message for a sub-message transmitted by the device includes the command message identifier included in the sub-message and, optionally, the channel identifier.

7. A method according to any one of claims 1-6, wherein the device is communicatively couplable with the controller via a plurality of wireless channels including the at least one wireless channel, wherein the method further comprises: if the controller, after the first period of time has elapsed and, following the elapse of a second period of time, has not yet received any acknowledgement message, the controller re-transmitting the command message in the wireless channel corresponding to the channel identifier and / or transmitting the command message in the other one(s) of the plurality of wireless channels.

8. A method according to claim 7, wherein if the controller subsequently receives an acknowledgement message which includes a channel identifier different from the channel identifier stored in the memory of the controller, the controller replacing the channel identifier stored in the memory of the controller with the channel identifier included in the acknowledgement message.

9. A method according to any one of claims 1-8, wherein the transmission by the device, for at least one of the N sub-messages, of an acknowledgement message after a waiting period of time has elapsed following the receipt of the sub-message, comprises: the device, for each sub-message of the N sub-messages that is received by the device, and of the device has not yet received any sub-message including the command message identifier in the sub-message, transmitting an acknowledgement message after a waiting period of time has elapsed following the receipt of the sub-message, wherein the device determines the waiting period of time based on at least N, the first period of time and the incremental sub-message identifier of the sub-message.

10. A method according to any one of claims 1-9, wherein the device comprises or is comprised in a lighting device configured to controllably emit light, wherein the command included in the command message is a command to control emission of light from the lighting device.

11. A method according to any one of claims 1-10, wherein the channel identifier stored in the memory of the controller has been previously determined by the carrying out of a pairing process to establish a relationship between the controller and the device for wireless communications.

12. A method according to any one of claims 1-11, wherein the controller is further communicatively coupled or couplable with at least one other device and further configured to control operation of the at least one other device, wherein the at least one other device is communicatively couplable with the controller via the at least one wireless channel, and wherein the transmission by the controller of the command message in the wireless channel corresponding to the channel identifier stored in the memory of the controller comprises the controller broadcasting the command message in the wireless channel corresponding to the channel identifier stored in the memory of the controller, and wherein the command included in the command message is to control operation of each of the said devices, wherein each of the said devices receiving the command message after receipt of the command operates according to the command included in the command message.

13. A system (10) comprising: a controller (1); anda device (2) communicatively coupled or couplable with the controller via at least one wireless channel, wherein the controller has a memory (4) in which a previously determined channel identifier of the wireless channel (3) of the at least one wireless channel for communication between the controller and the device is stored; wherein: the controller is configured to transmit a command message in the wireless channel corresponding to the channel identifier stored in the memory of the controller, the command message including a command to control operation of the device and a command message identifier identifying the command message, wherein the command message includes N sub-messages transmitted successively over a first period of time (Tl), wherein N > 1, and wherein each of the N sub-messages includes: the command, the command message identifier, and an incremental sub-message identifier, wherein the incremental submessage identifiers for the respective ones of the N sub-messages are different relatively to each other and indicate the relative temporal positions of the N sub-messages in the first period of time, wherein the device is configured to obtain, or has previously obtained, indications of N and the selected first period of time; the device is configured to, for at least one of the N sub-messages, transmit an acknowledgement message after a waiting period of time has elapsed following the receipt of the sub-message, wherein the device determines the waiting period of time based on at least N, the first period of time and the incremental sub-message identifier of the sub-message; the controller is configured to enter a power saving state upon receipt of the acknowledgement message.

14. A controller (1) in a system (10) according to claim 13.

15. A device (2) in a system (10) according to claim 13.

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