A method for switching a role of a node in a wireless network

Abstract

A method (600) for switching a role of a node in a wireless network; the method (600) comprising the steps of the bridge device (150):receiving (S601) a command to add a new node (400) to the wireless network (100); sending (S602) a request to one or more nodes out of the plurality of nodes to carry out a scan for neighbor nodes; receiving (S603) one or more scan reports from the one or more nodes; selecting (S604), based on the received 5 one or more scan reports, a sleepy end node (300') to switch to a router node role to facilitate the access of the new node (400) to the wireless network (100); and sending (S605) an instruction to the selected sleepy end node (300') to switch to a router node (200).

Description

[0001] A method for switching a role of a node in a wireless network

[0002] FIELD OF THE INVENTION

[0003] The invention relates to the field of wireless communication. More particularly, various methods, apparatus, and systems are disclosed herein related to adaptively switching a role of node in a wireless network.

[0004] BACKGROUND OF THE INVENTION

[0005] Wireless connected control systems are widely adopted in different application scenarios, such as building automation, smart homes, industrial automation, and healthcare facilities. This technology provides low-latency communication between sensors, actuators, and other devices, enabling real-time control and monitoring.

[0006] Such a system typically comprises a central controller that communicates with a plurality of devices in the system using short-range wireless communication protocols, such as Zigbee, Thread, Bluetooth, Bluetooth Mesh or Z-Wave. These protocols have advantages on supporting low-power, low-data-rate applications, making them ideal for use in connected control systems.

[0007] Lighting industry is also moving towards wireless connected control systems, which offer greater flexibility and convenience, where the lighting and non-lighting devices (luminaires, switches, sensors etc.) interact with each other by forming wireless networks. These systems allow users to control their lights remotely, such as adjusting the intensity and colour temperature, scheduling when the lights turn on and off. Connected lighting components such as LEDs and drivers are getting more energy efficient and as a result the power consumption of connectivity components both during operation and standby is becoming an increasingly important factor.

[0008] One way to reduce the power consumption is to optimize the wireless network by limiting the number of routers required in the network and switching remaining devices to (sleepy) end device role. Since end devices can go to sleep and poll / listen to their parents (Routers) at regular intervals to get messages queued for them by the parent, the overall power consumption used for obtaining connectivity is reduced. Sometimes, this mode of network operation is called an “Eco-mode”. US2018139796A1 relates to a method and apparatus for managing connectivity between a cellular network (in which device communicate via long-range wireless technology) and devices in one or more multi-hop capillary networks (in which devices communicate via short-range wireless technology).

[0009] SUMMARY OF THE INVENTION

[0010] Since the number of routers in the network may be limited when the network is in an Eco-mode, a newly added device might not be in the vicinity of available routers and the network joining process for the new device may fail as its beacon request will not reach any of the available routers. Thus, it is necessary to provide a solution to keep the entire system power efficient but still responding to the new device, without degrading the user experience.

[0011] It is recognized by the inventor that it is beneficial to adaptively switch the role of a node in a wireless network to deal with such demand. More particularly, the goal of this invention is achieved by a method as claimed in claim 1, by a bridge device as claimed in claim 10, and by a wireless control network as claimed in claim 14.

[0012] In accordance with a first aspect of the invention a method is provided. A method for switching a role of a node in a wireless network comprising a bridge device and a plurality of nodes, among which a subset of the plurality of nodes are configured to operate as router nodes and another subset of the plurality of nodes are configured to operate as sleepy end nodes; the method comprising the steps performed by the bridge device: receiving a command to add a new node to the wireless network; wherein the command is received on a user interface of the bridge device, or from a user device, or via a node out of the plurality of nodes; sending a request to one or more nodes out of the plurality of nodes to carry out a scan for neighbor nodes; receiving one or more scan reports from the one or more nodes; selecting, based on the received one or more scan reports, a sleepy end node that is most adjacent to the new node to switch to a router node role to facilitate the access of the new node to the wireless network; and sending an instruction to the selected sleepy end node to switch to a router node.

[0013] The wireless network may be used as a control network, and the bridge device may be a central controller or coordinator of the control network. The command to add a new node may be received by the bridge device or the central controller via a communication interface. The communication interface may be a wired communication interface or a wireless communication interface. For example, the communication interface may be based on Cellular, Wi-Fi, Bluetooth, BLE, Zigbee, Z-wave, Thread, NFC, Ethernet, or USB.

[0014] It may also be possible that the command is received on a user interface of the bridge device or the central controller. For example, the user interface may be a touch screen, a keyboard, a voice or gesture recognition interface.

[0015] In a further option, the command is received by the bridge device or central controller via a node in the wireless network. For example, the node may have an aforementioned communication interface or user interface, and the command is then forwarded by the node to the bridge device or central controller over the wireless network.

[0016] The plurality of nodes is configured to operate in different roles. In a mesh network, typically a router node is configured to forward packets directed to other nodes in the network, and an end node do not take any networking responsibility as it does not route data between nodes. A sleepy end node is a type of end node that conserves power by entering a low-power sleep mode when it is not actively transmitting or receiving data. This mode allows the device to use less power and extend its battery life. When the sleepy end node needs to send or receive data, it wakes up from sleep mode and resumes normal operation.

[0017] With the plurality of nodes configured to operate as either router nodes or sleepy end nodes, it may happen that the new node to be added to the wireless network is not in a direct communication range of any router node. Since the sleepy end nodes are in the sleep mode most of the time, a request from the new node to join the wireless network may not be detected. It is thus necessary that upon receiving a command to add a new node the bridge device sends a request to a subset of the plurality of nodes to carry out a scan for neighbor nodes. Of course, it is also possible that the bridge device requests all the sleepy end nodes to wake up to carry out the scan for neighbor nodes. Each one of the nodes that are requested to scan for neighbor nodes will then generate a scan report and send to the bridge device. A scan report comprises information about the neighboring nodes detected by an individual node. And then, based on the scan reports received, the bridge device can select a sleepy end node to switch to a router node role to facilitate the access of the new node to the wireless network, for example, a sleepy end node that is most adjacent to the new node may be selected. The bridge device will then send an instruction to the selected sleepy end node to switch to a router node.

[0018] Advantageously, the method may further comprise a step of: monitoring on the wireless network for a request to join from the new node for a predetermined time duration; wherein the request to the one or more nodes is sent when no request to join from the new node is received within the predetermined time duration.

[0019] Beneficially, the method may further comprise a step of: determining, based on topology information of the wireless network, the one or more nodes to request to carry out a scan for neighbor nodes.

[0020] The topology information refers to the physical or logical arrangement of the nodes in the network. Physical topology is related to the placement of the plurality of node in the system, while logical topology is related to the data flows within the network, such as data links among the plurality of nodes.

[0021] In one example, the one or more nodes that are requested to carry out the scan for the new node are mostly located at the edge of the wireless network.

[0022] In one option, the selected sleepy end node may be instructed to switch to a router node by rejoining the wireless network with same network credentials as used in the sleepy end node role.

[0023] It is beneficial that the selected sleepy end node rejoins the network as a router node with same network credentials. For example, the selected node may use the same network address and / or identification.

[0024] Beneficially, each one of the one or more scan reports comprises a list of identifications of neighbor nodes.

[0025] Preferably, each one of the one or more scan reports further comprises a link quality indication for each of the neighbor nodes.

[0026] When there is more than one node in the direct communication range of the new node, additional link quality information may assist the bridge device to make a better selection.

[0027] Advantageously, the request to the one or more nodes to carry out a scan for neighbor nodes further comprises information related to the new node.

[0028] The bridge device may also indicate the identification or name of the new node, such that the one or more nodes requested to carry out the scan may stop the procedure as soon as the new node is found. It may also be an option that the bridge device sets a duration for the scan procedure in the request. And then the one or more nodes will send back the scan report at the end of the scan duration.

[0029] In one example, the scan for neighbor nodes is carried out with another wireless communication protocol different from the wireless communication protocol used by the wireless network.

[0030] The scan may be carried out based on BLE, Wi-Fi direct, Z-Wave, thread, or another peer-to-peer communication protocol that is different from the wireless communication protocol used by the wireless network.

[0031] Beneficially, the method further comprises a step of: selecting, based on the received one or more scan reports, a router node to switch to a sleepy end node role when the router node is located close to the sleepy end node that is selected to switch to the router node; and sending another instruction to the selected router node to switch to a sleepy end node.

[0032] Similarly, based on the scan reports, the bridge device may also decide to select a router node to switch to a sleepy end node. For example, this may be decided when a newly selected router node is close to both this router node and the new node. It is then more efficient to switch the roles of the two nodes, instead of keeping two router nodes.

[0033] In accordance with a second aspect of this invention a bridge device is provided. A bridge device in a wireless network comprising the bridge device and a plurality of nodes, among which a subset of the plurality of nodes are configured to operate as router nodes and another subset of the plurality of nodes are configured to operate as sleepy end nodes; the bridge device comprising: a first communication interface configured to receive a command, from a user, a user device or via a node out of the plurality of nodes, to add a new node to the wireless network; a second communication interface configured to: send a request to one or more nodes out of the plurality of nodes to carry out a scan for neighbor nodes; and receive one or more scan reports from the one or more nodes; and a controller configured to select, based on the received one or more scan reports, a sleepy end node that is most adjacent to the new node to switch to a router node role to facilitate the access of the new node to the wireless network; and control the second communication interface to send an instruction to the selected sleepy end node to switch to a router node.

[0034] The wireless network may be used as a control network, and the bridge device may be a central controller or coordinator of the wireless network. The bridge device may also be a gateway or a central switch of the wireless network.

[0035] In one example, the second communication interface is further configured to monitor on the wireless network for a request to join from the new node for a predetermined time duration; wherein the request to the one or more nodes is sent when no request to join from the new node is received within the predetermined time duration.

[0036] In one option, the first communication interface is different from the second communication interface.

[0037] The first communication interface may be related to a point-to-point connection, such as in accordance with a Bluetooth low energy, BLE, standard. It can also be Wi-Fi direct, Zigbee Touchlink, or another wireless communication standard that favours an easy setup for point-to-point connection. Alternatively, the first communication interface may also be based on another wired or wireless communication protocol, such as Cellular, Wi-Fi, Bluetooth, Thread, NFC, Ethernet, or USB. In a further option, the first communication interface may be a user interface of the bridge device, such as a touch screen, a keyboard, a voice or gesture recognition interface.

[0038] The second communication interface may be used to support the control function of the plurality of nodes, such as lighting control or building automation. Preferable, the second communication protocol supports multi-hop communication, which can be Zigbee, Thread, Bluetooth Mesh, Wi-Fi mesh, WirelessHART, SmartRF, CityTouch, IP500, Z-wave, or any other mesh or tree-based technology.

[0039] For example, ZigBee specifies three different device types: the ZigBee Coordinator (ZC), the ZigBee Router (ZR), and the ZigBee End Device (ZED). These three devices play different roles in a ZigBee network. A Zigbee Router (ZR) passes data between devices and / or the coordinator. A Zigbee End Device (ZED) provides only basic functionality. ZEDs are leaf nodes. They communicate only through their parent nodes and, unlike router devices, cannot relay messages intended for other nodes. They don’t participate in any routing. End devices rely on their parent routers to send and receive messages. Regarding IEEE 802.15.4, ZC and ZR are fully functional devices (FFDs), whereas the ZEDs are reduced function devices (RFDs). A Sleepy End Device is a special kind of end device, which turns off its radio when idle, which makes it a suitable choice for battery operated devices. The bridge device may be a Zigbee Coordinator of the wireless network.

[0040] The first communication interface and the second communication interface may be supported by two different modules, such that they can operate independently. In another option, the two communication interfaces are enabled by a single radio, such as a dual mode radio. And then, the two communication interfaces may operate in a time- interleaved manner.

[0041] Beneficially, the controller is further configured to select, based on the received one or more scan reports, a router node to switch to a sleepy end node role when the router node is located close to the sleepy end node that is selected to switch to the router node; and control the second communication interface to send another instruction to the selected router node to switch to a sleepy end node.

[0042] In accordance with a third aspect of this invention a wireless control network is provided. A wireless control network comprising a bridge device according to the present invention and a plurality of nodes; wherein the bridge device is configured to carry out the steps according to the present invention; wherein a subset of the plurality of nodes are configured to operate as router nodes and another subset of the plurality of nodes are configured to operate as sleepy end nodes.

[0043] Preferably, at least one of the plurality of nodes is coupled to a lighting fixture for lighting control.

[0044] Lighting systems are becoming more and more wirelessly connected for both professional and home use cases. For example, the wireless control network may be deployed as part of a control system used for building automation, smart homes, industrial automation, and healthcare facilities.

[0045] BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In the drawings, like reference characters generally refer to the same parts throughout the different figures. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention.

[0047] Fig. 1 illustrates a wireless communication network comprising a plurality of nodes;

[0048] Fig. 2 shows a basic block diagram of a bridge device; and Fig. 3 shows a flow chart of a method for switching a role of a node in a wireless network.

[0049] DETAILED DESCRIPTION OF EMBODIMENTS

[0050] The embodiments set forth below represent information to enable those skilled in the art to practice the embodiments. Upon reading the following description in light of the accompanying drawings, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure.

[0051] FIG. 1 illustrates a wireless communication network 100 comprising a plurality of nodes 200, 300 and a bridge device 150. A subset of the plurality of nodes are configured to operate as router nodes 200 and another subset of the plurality of nodes are configured to operate as sleepy end nodes 300.

[0052] The plurality of nodes may be coupled to or integrated in wireless controlled devices in home and building automation scenarios. The wireless controlled devices may be one of smart thermostats, smart lighting, smart locks, smart blinds and shades, smart appliances (e.g., refrigerators, ovens, vacuum cleaner, or washing machines), smart security systems comprising cameras, motion sensors, and alarms.

[0053] In one example, at least one of the plurality of nodes is coupled to a lighting fixture for lighting control.

[0054] In the example of FIG. 1, the newly added device 400 is close to a sleepy end device 300. It is beneficial to switch the sleepy end device 300’ that is in the vicinity of the newly added device to a router, which may then act as a parent for the newly added device 400. As one example, the wireless communication network 100 operates according to a Zigbee standard.

[0055] In a Zigbee network, an ECO mode is defined to conserve energy and extend the battery life of Zigbee devices. In this mode, devices may reduce their power consumption by lowering their transmission power, reducing the frequency of network scanning and data transmission, and by using low-power sleep modes. ECO mode is particularly important for battery-powered devices, such as sensors and actuators, which are often deployed in large numbers in Zigbee networks. By conserving energy, these devices can operate for longer periods of time without needing to replace or recharge their batteries. With an ECO mode, how to add a new device timely without degrading user experience becomes a challenge. To solve this problem, an exemplary procedure may proceed as follows:

[0056] 1. Newly added device 400 is factory new and sends out regular beacon messages when it is powered on. For example, this beacon message may be Bluetooth Low Energy advertisements.

[0057] 2. Bridge device 150 receives a “add new device” command from the user’s smartphone.

[0058] 3. Bridge device 150 first runs the regular / existing Zigbee commissioning process where the network is opened to see if any new devices show up within a certain amount of time. If that's not the case, bridge device 150 instructs all the devices 200, 300 in the Zigbee network to perform a Bluetooth Low-Energy scan.

[0059] 4. Scan results are sent back by the devices 200, 300 to the Bridge device 150.

[0060] 5. In this case, only device 300’ catches beacon messages of new device 400 and no other router device or end node detects beacon messages of new device 400.

[0061] 6. Bridge device 150 instructs sleepy end node 300’ to switch to a router via the Zigbee network.

[0062] 7. Sleepy end node 300’ switches to router and rejoins the network using same network credentials as before.

[0063] 8. Sleepy end node 300’ receives Zigbee beacon request from new device 400.

[0064] 9. Sleepy end node 300’ responds with the Zigbee beacon response.

[0065] 10. Zigbee joining procedure is completed by the new device 400.

[0066] Additionally, to instruct a device to switch to a router, it is possible to define a special “router mode switch” message for sleepy end devices, such that when received by the sleepy device, switches the device back to router mode. To this end, the sleepy end device rejoins the network in a router role, using the same network parameters. When needed, the message may be sent to a specific group of sleepy end devices as required. For example, only to the end devices at the edge of the network that potentially have a larger chance to see new devices being added. A centralized device like bridge can know the complete network graph and based on that information can select end devices at the edge of the network. The message may be sent by any node based on certain parameters, such as the network being opened to add new devices.

[0067] The above example is provided based on a Zigbee network. However, the wireless network may operate according to another multi-hop based communication protocol, such as Thread, Bluetooth Mesh, Wi-Fi mesh, WirelessHART, SmartRF, CityTouch, IP500, Z-wave.

[0068] FIG. 2 shows a basic block diagram of a bridge device 150. As a basic setup, the bridge device 150 comprises a first communication interface 151, a second communication interface 152, and a controller 153. The first communication interface 151 is configured to receive a command to add a new node 400 to the wireless network 100. The second communication interface 152 is configured to send a request to one or more nodes out of the plurality of nodes to carry out a scan for neighbor nodes; and receive one or more scan reports from the one or more nodes. The controller 153 is configured to select, based on the received one or more scan reports, a sleepy end node 300 to switch to a router node role to facilitate the access of the new node 400 to the wireless network 100; and control the second communication interface to send an instruction to the selected sleepy end node 300 to switch to a router node 200. The controller 153 may be further configured to select, based on the received one or more scan reports, a router node 200 to switch to a sleepy end node role; and control the second communication interface to send another instruction to the selected router node 200 to switch to a sleepy end node 300.

[0069] In one example, the second communication interface 152 is further configured to monitor on the wireless network 100 for a request to join from the new node 400 for a predetermined time duration, and the request to the one or more nodes is sent when no request to join from the new node 400 is received within the predetermined time duration.

[0070] The first communication interface 151 may be same as the second communication interface. In this option, the command is also received via the wireless communication network.

[0071] Alternatively, the first communication interface 151 is different from the second communication interface 152.

[0072] The first communication interface 151 may be related to a point-to-point communication protocol, such as in accordance with a Bluetooth low energy, BLE, standard. It can also be Wi-Fi direct, Zigbee Touchlink, or another wireless communication standard that favours an easy setup for point-to-point connection.

[0073] Alternatively, the first communication interface may also be based on another wired or wireless communication protocol, such as Cellular, Wi-Fi, Bluetooth, Thread, NFC, Ethernet, or USB. In a further option, the first communication interface may be a user interface of the bridge device, such as a touch screen, a keyboard, a voice or gesture recognition interface.

[0074] The second communication interface may be used to support the control function of the plurality of nodes, such as lighting control or building automation. Preferable, the second communication protocol supports multi-hop communication.

[0075] FIG. 3 shows a flow chart of a method 600 for switching a role of a node in a wireless network 100. A method 600 for switching a role of a node in a wireless network 100 comprising a bridge device 150 and a plurality of nodes 200, 300, among which a subset of the plurality of nodes 200, 300 are configured to operate as router nodes 200 and another subset of the plurality of nodes 200, 300 are configured to operate as sleepy end nodes 300; the method 600 comprising the steps of the bridge device 150: receiving, in step S601, a command to add a new node 400 to the wireless network 100; sending, in step S602, a request to one or more nodes out of the plurality of nodes to carry out a scan for neighbor nodes; receiving, in step S603, one or more scan reports from the one or more nodes; selecting, in step S604, based on the received one or more scan reports, a sleepy end node 300’ to switch to a router node role to facilitate the access of the new node 400 to the wireless network 100; and sending, in step S605, an instruction to the selected sleepy end node 300’ to switch to a router node 200.

[0076] The method 600 may further comprise a step of: monitoring on the wireless network 100 for a request to j oin from the new node 400 for a predetermined time duration; wherein the request to the one or more nodes is sent when no request to join from the new node 400 is received within the predetermined time duration.

[0077] The method 600 of claim 1 or 2 further comprising a step of: determining, based on topology information of the wireless network 100, the one or more nodes to request to carry out a scan for neighbor nodes.

[0078] The method according to the present invention may be implemented on a computer as a computer implemented method, or in dedicated hardware, or in a combination of both.

Claims

CLAIMS:

1. A method (600) for switching a role of a node in a wireless network (100) comprising a bridge device (150) and a plurality of nodes (200, 300, 300’), among which a subset of the plurality of nodes are configured to operate as router nodes (200) and another subset of the plurality of nodes are configured to operate as sleepy end nodes (300, 300’); the method (600) comprising the steps performed by the bridge device (150): receiving (S601) a command to add a new node (400) to the wireless network (100); wherein the command is received on a user interface of the bridge device, or from a user device, or via a node out of the plurality of nodes; sending (S602) a request to one or more nodes out of the plurality of nodes to carry out a scan for neighbor nodes; receiving (S603) one or more scan reports from the one or more nodes; selecting (S604), based on the received one or more scan reports, a sleepy end node (300’) that is most adjacent to the new node to switch to a router node role to facilitate the access of the new node (400) to the wireless network (100); and sending (S605) an instruction to the selected sleepy end node (300’) to switch to a router node (200).

2. The method (600) of claim 1 further comprising a step of: monitoring on the wireless network ( 100) for a request to j oin from the new node (400) for a predetermined time duration; wherein the request to the one or more nodes is sent when no request to join from the new node (400) is received within the predetermined time duration.

3. The method (600) of claim 1 or 2 further comprising a step of: determining, based on topology information of the wireless network (100), the one or more nodes to request to carry out a scan for neighbor nodes.

4. The method (600) of any one of the previous claims, wherein the selected sleepy end node (300’) is instructed to switch to a router node (200) by rejoining the wireless network (100) with same network (100) credentials as used in the sleepy end node role.

5. The method (600) of any one of the previous claims, wherein each one of the one or more scan reports comprises a list of identifications of neighbor nodes.

6. The method (600) of claim 5, wherein each one of the one or more scan reports further comprises a link quality indication for each of the neighbor nodes.

7. The method (600) of any one of the previous claims, wherein the request to the one or more nodes to carry out a scan for neighbor nodes further comprises information related to the new node (400).

8. The method (600) of any one of the previous claims, wherein the scan for neighbor nodes is carried out with another wireless communication protocol different from the wireless communication protocol used by the wireless network (100).

9. The method (600) of any one of previous claims further comprising a step of: selecting, based on the received one or more scan reports, a router node (200) to switch to a sleepy end node role when the router node is located close to the sleepy end node (300’) that is selected to switch to the router node; and sending another instruction to the selected router node (200) to switch to a sleepy end node (300).

10. A bridge device (150) in a wireless network (100) comprising the bridge device (150) and a plurality of nodes (200, 300, 300’), among which a subset of the plurality of nodes are configured to operate as router nodes (200) and another subset of the plurality of nodes are configured to operate as sleepy end nodes (300, 300’); the bridge device (150) comprising: a first communication interface (151) configured to receive a command, from a user, a user device or via a node out of the plurality of nodes, to add a new node (400) to the wireless network (100);a second communication interface (152) configured to: send a request to one or more nodes out of the plurality of nodes to carry out a scan for neighbor nodes; and receive one or more scan reports from the one or more nodes; and a controller (153) configured to select, based on the received one or more scan reports, a sleepy end node (300’) that is most adjacent to the new node to switch to a router node role to facilitate the access of the new node (400) to the wireless network (100); and control the second communication interface to send an instruction to the selected sleepy end node (300) to switch to a router node (200).

11. The bridge device (150) of claim 10, wherein: the second communication interface (152) is further configured to monitor on the wireless network (100) for a request to join from the new node (400) for a predetermined time duration; wherein the request to the one or more nodes is sent when no request to join from the new node (400) is received within the predetermined time duration.

12. The bridge device (150) of claim 10 or 11, wherein the first communication interface (151) is different from the second communication interface (152).

13. The bridge device (150) according to any one of the previous claims 10-12, wherein the controller (153) is further configured to select, based on the received one or more scan reports, a router node (200) to switch to a sleepy end node role when the router node is located close to the sleepy end node (300’) that is selected to switch to the router node; and control the second communication interface to send another instruction to the selected router node (200) to switch to a sleepy end node (300).

14. A wireless control network (100) comprising a bridge device (150) according to any one of the previous claims 10-13 and a plurality of nodes (200, 300, 300’); wherein the bridge device (150) is configured to carry out the steps according to any one of the previous claims 1-9; wherein a subset of the plurality of nodes are configured to operate as router nodes (200) and another subset of the plurality of nodes are configured to operate as sleepy end nodes (300, 300’).

15. The wireless control network (100) of claim 14, wherein at least one of the plurality of nodes is coupled to a lighting fixture for lighting control.

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