Wireless control system based on hybrid network

Abstract

To improve the efficiency and reliability of communication, such as for control command distribution and data collection, in a large and high-density wireless control system (100), each of a plurality of nodes in the system is assigned one of three roles: a router node (200), a non-router node (300), or a data collector node (400). The nodes (200, 300, 400) in the wireless control system (100) are capable of operating according to at least one of two communication protocols. The first communication protocol can support a mesh or tree network with multi-hop routing, while the second communication protocol can support a star network with point-to-point connections. The router nodes construct a sparse multi-hop network to guarantee connectivity of the large-scale network. Around each router node within a one-hop direct link, a local star network is constructed with at least one non-router node and at least one data collector node.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of wireless control systems. More particularly, disclosed herein are various methods, apparatuses, systems, and computer-readable media related to wireless control systems for distributing control commands to and forwarding information from a plurality of nodes using a hybrid network topology approach. BACKGROUND

[0002] An ongoing trend in the professional lighting market is the move towards connected lighting systems, which enable all kinds of new features like (remote) scheduling, energy monitoring, sensor-based lighting control, and asset management. In many cases, these systems are installed in existing buildings, in which case wireless networks are preferred to avoid having to deploy new cabling (for lighting control) through the ceiling. Examples of such wireless network protocols that are widely used in current practice are open standards like Zigbee, Thread, BLE, BLE mesh, Wi-Fi, Wi-Fi direct, and various proprietary network implementations built on top of IEEE 802.15.4, IEEE 802.15.1, or IEEE 802.11 standards.

[0003] In many cases, the network can be very large, so that a direct link from a central controller can not reach all nodes, and thus those remote nodes can need help from one or more relay nodes. Flooding-based routing methods are widely used to distribute control messages to a large number of nodes. Many nodes broadcast and receive messages simultaneously, and if each node repeats the message a few times, the probability of losing the message becomes low enough to be acceptable. Depending on the size and density of the network, the number of repetitions can be configured (in some networks) in order to suppress the “network storm” caused by the broadcast. Without such suppression, each node would typically resend the message a limited number of times. Otherwise, in a network of 200 nodes, a single broadcast message can easily result in tens of thousands of retransmissions.

[0004] However, for control systems that include a large number of nodes deployed at high node density, collisions occur because many nodes are within direct communication range. Such flooding-based routing can not be very efficient. SUMMARY

[0005] In view of the above, the present disclosure is directed to methods, apparatuses, systems, computer programs and computer readable media for providing mechanisms related to a wireless control network system for distributing information to and forwarding information from a large number of nodes in a more efficient and reliable way. Thus, the control system is implemented in a wireless communication network. More particularly, the object of the invention is achieved by a wireless control system as claimed in claim 1, a node of the plurality of nodes in the wireless control system as claimed in claim 12, a method of the wireless control system as claimed in claim 13, a method of the node as claimed in claim 14, a distributed computer program of the system as claimed in claim 15, and a computer program of the node as claimed in claim 16.

[0006] Thus, in order to improve the efficiency and reliability of information distribution and collection in large and dense networks, a hybrid network topology with a combination of mesh and star topology is constructed by utilizing two different communication protocols (a first communication protocol and a second communication protocol), and assigning one of three different roles to each of the plurality of nodes. The first communication protocol has multi-hop routing capability, and the second communication protocol supports point-to-point connections. By utilizing the two communication protocols in the hybrid network topology, a more efficient way of communication is achieved. Preferably, the different communication protocols use different frequency allocation schemes, and thus according to the two different communication protocols, more concurrent communication can take place on different frequency bands / channels.

[0007] According to a first aspect of the invention, a wireless control system is provided. The wireless control system comprises a plurality of nodes configured to operate according to at least one of a first communication protocol capable of supporting a mesh or tree network with multi-hop routing; and a second communication protocol capable of supporting a star network with point-to-point connections. Each node of the plurality of nodes is assigned one of three roles, and each of the three roles is assigned to at least one node of the plurality of nodes, the three roles being:

[0008] - a first role, wherein the node is configured to operate in a first mode according to the first communication protocol, wherein the routing capability of the node is enabled, and the node is operable to distribute control commands to the plurality of nodes, and to forward state information received from the plurality of nodes via multi-hop routing;

[0009] - a second role, wherein the node is configured to operate in a second mode according to the first communication protocol, wherein the routing capability of the node is disabled, and the node is operable to receive control commands broadcast by another node of the plurality of nodes by means of a one-hop direct link; and in a third mode according to the second communication protocol, wherein the node is operable to send state information to one or more nodes of the plurality of nodes; and

[0010] - a third role, wherein the node is configured to operate in a fourth mode according to the second communication protocol, wherein the node is operable to receive state information from one or more of the plurality of nodes by means of a point-to-point connection; and in a fifth mode according to the first communication protocol, wherein the node is operable to transmit aggregated state information received from the one or more nodes in the fourth mode to a parent node of the plurality of nodes by means of a one-hop direct link; and wherein the parent node is a node assigned the first role or a node assigned the second role.

[0011] In one example, the wireless control system can be a one-to-many network with a central controller or gateway device and a plurality of nodes to be controlled. Control commands distributed over the network can come from the local central controller or from the cloud via the gateway device. The central controller or gateway device will send out control commands to the large distributed network in a centralized fashion. In turn, the plurality of nodes in the large distributed network are configured to provide feedback to the central controller or cloud with state information related to the functional devices or actuators controlled by the central controller or cloud. In addition to actuators, there can be other sensors co-located with the plurality of nodes. Thus, the state information can also include sensing data from other sensors, such as data related to temperature, humidity, etc. Thus, in one preferred example, the communication in the system can be one-to-many or many-to-one.

[0012] Nodes assigned the first role act as router nodes according to the first communication protocol. In case the multi-hop routing capability is enabled, the router nodes are configured to relay control commands and status information or sensing data to and from multiple nodes in a bidirectional manner. Nodes assigned the second role act as non-router nodes, operating mainly according to the first communication protocol, while the routing capability is disabled. The non-router nodes utilize one-hop direct link detection of control commands broadcast by nodes assigned the first role and send out their own status information or sensing data via point-to-point connections according to the second communication protocol. Here, point-to-point connections are considered to encompass also point-to-multipoint connections. Nodes assigned the third role act as data collector nodes. The data collector nodes operate mainly according to the second communication protocol to collect status information or sensing data from one or more nodes in the surrounding environment. The data collector nodes aggregate the collected information or data during a certain time period and thereafter send it in a single data packet, preferably using one-hop direct link, to a parent node. The time period can be determined according to the size of the collected status information or sensing data, or the capacity of the single data packet, or the latency requirements of collecting such information or data. Assuming that typical status information and sensing data have a relatively low data rate compared to the network capacity, but can have very critical latency requirements, aggregating information and data from multiple nodes in a single data packet can make transmissions in large networks according to the first communication network more efficient in terms of reducing packet overhead, such as packet headers, and reducing potential collisions between multiple simultaneous transmissions.

[0013] By assigning one of the three roles to each of the multiple nodes, the original large dense network transforms into a sparse multi-hop network in view of the first communication protocol. The sparse multi-hop network mainly comprises nodes assigned the first role or router nodes, which stay in the first mode most of the time. Around each router node, a local star network is built with nodes assigned the second or third roles, which either communicate via one-hop direct link according to the first communication protocol, or via point-to-point or point-to-multipoint connections according to the second communication protocol. Thus, by utilizing the two communication protocols and assigning certain one of the three roles to a single node, a hybrid network topology is constructed in the wireless control system.

[0014] It is noted that packet collisions in a sparse multi-hop network should be limited as much as possible, because those packets can have travelled along a long path and retransmitting such packets can be quite resource consuming in terms of both network bandwidth and power consumption. By reducing the number of nodes participating in multi-hop relaying, collisions in a sparse network according to the first communication protocol are greatly reduced. Non-router nodes listen purely according to the first communication protocol, but do not transmit. And thus, in a sparse multi-hop network according to the first communication protocol, non-router nodes will not cause collisions. Although the data collector node transmits data packets with aggregated state information or sensed data to the parent node according to the first communication protocol, such data packets are transmitted intermittently. Moreover, because the parent node is preferably separated from the data collector node by a one-hop direct link, reduced transmission power can be used to further reduce potential interference from the data collector node to the sparse multi-hop network.

[0015] The parent node or data collector node of the node assigned the third role is responsible for acting as an interface between the data collector node and the network, which is a sparse multi-hop network according to the first communication protocol. The interface involves bidirectional communication. In one direction, the parent node receives data from the end node (data collector node) and forwards the data to the sparse multi-hop network. Preferably, when the node assigned the first role is a parent node of the node assigned the third role, the node assigned the first role is further configured to operate in a first mode to forward aggregated state information received from the node assigned the third role to the next hop via multi-hop routing.

[0016] On the other hand, the parent node is responsible for delivering control commands from the sparse multi-hop network to the end node. When the node assigned the first role (router node) is a parent node or data collector node of the node assigned the third role, the data collector node can switch to operate according to the first communication protocol to occasionally poll the parent node to check whether there are any available control commands, although the inherent latency due to the polling mechanism is not most desirable.

[0017] In another example, the node assigned the second role is a parent node of the node assigned the third role, the node assigned the second role is further configured to operate in a second mode according to the first communication protocol when forwarding aggregated state information received from the node assigned the third role to the node assigned the first role via a one-hop direct link. This can be beneficial if the link quality between the data collector node and the non-router node is much better than the link quality between the data collector node and the router node.

[0018] In one example, the point-to-point connection according to the second communication protocol can also be a point-to-multipoint connection. In a preferred setting, the second wireless communication protocol complies with the Bluetooth Low Energy, BLE, standard. It is beneficial to utilize the simple setup of a point-to-point or point-to-multipoint connection, such as a BLE beacon, by a node assigned the second role to send status information to at least one node assigned the third role. Here we consider that a point-to-point connection also encompasses a point-to-multipoint connection.

[0019] In another preferred setting, the first wireless communication protocol complies with the Zigbee standard. The Zigbee standard is widely adopted in home automation and lighting control applications. The Zigbee network layer itself supports both star and tree networks as well as general mesh networking. The strong topology control provides great flexibility in control systems, especially for reaching destination nodes far away from the source node with direct links.

[0020] In such large and dense networks, it can be the case that multiple nodes are a mix of legacy devices capable of operating according to only one of the two communication protocols and more advanced devices capable of operating according to both the first and second communication protocols. Depending on the physical properties of a certain node, a subset of the three roles can be assigned as potential roles for that node.

[0021] In another embodiment, each node of the plurality of nodes can be assigned any one of the three roles.

[0022] In this preferred setting, each node of the plurality of nodes is capable of operating according to the first and second communication protocols. And thus, any one of the three roles can be assigned to any one node, with the result that the same node can be installed at one location and configured at a later time.

[0023] In another preferred setting, the role assignment to the plurality of nodes can also change over time. This added flexibility can be triggered when there is a failure of a single node, or a link quality degradation of a certain connection due to noise or interference, or a mobility of a certain node.

[0024] In one embodiment, the node of the plurality of nodes assigned the second role is further configured to, when receiving a control command in the second mode, operate in a third mode, at which the received control command is forwarded to one of the plurality of nodes assigned the third role by means of the point-to-point connection.

[0025] Assuming that the node or data collector node assigned the third role operates in the fourth mode most of the time, it can be the most efficient way to deliver control commands by the non-router nodes to the data collector node according to the second communication protocol. The control commands can also piggyback on the same packet with status information or sensing data from the non-router nodes.

[0026] In another embodiment, the node assigned the second role is further configured to operate in the third mode upon receiving a control command in the second mode, at which time a notification is sent to the node assigned the third role using the point-to-point connection.

[0027] Given the potentially different security levels provided by the first and second communication protocols, the node assigned the second role or non-router node can not forward the control command directly to the node assigned the third role or data collector node according to the second communication protocol. Instead, the non-router node can send a notification to the data collector node about the availability of a new control command from the sparse multi-hop network.

[0028] Preferably, the node assigned the third role is further configured to operate in a fifth mode according to the first communication protocol upon receiving the notification, at which time the parent node is polled for receiving the control command.

[0029] Beneficially, upon receiving the notification from the non-router node, the data collector will poll its parent node, most likely the router node. Such a trigger-based polling provides lower latency compared to regular polling scheduled according to a regular time interval, especially since the control commands are typically sporadically sent out without a fixed rhythm.

[0030] In one embodiment, the node assigned the first role is further configured to operate in a sixth mode according to the second communication protocol when sending status information via the point-to-point connection.

[0031] The node assigned the first role or router node can also include a collocated device, actuator or sensor. To provide status information and / or sensing data, the router node can operate according to the second communication protocol to deliver such information to the data collector node. And then status information and / or sensing data from the router node, non-router node and data collector node itself can be combined in the same packet.

[0032] In another example, a node or router node assigned the first role can be configured to stay on the sparse multi-hop network all the time according to the first communication protocol. Then, in addition to forwarding data packets containing aggregated state information and / or sensing data received from the data collector, the router node can generate a separate packet for its own state information and / or sensing data and forward the separate packet directly to the next hop via multi-hop routing. Alternatively, the router node can also piggyback its own state information and / or sensing data onto the aggregated data received from the data collector node and then forward the combined packet to the next hop via multi-hop routing.

[0033] Alternatively, when the router node is further configured to act as a parent node of the data collector node, the router node can also forward control commands directly to the data collector node in the sixth mode according to the second communication protocol. The router node can also send a notification about the control commands to the data collector node in the sixth mode to trigger the data collector node to switch to the first communication protocol to receive the control commands.

[0034] Advantageously, the nodes assigned the second role are further configured to operate in both the second mode and the third mode in a time-interleaved manner, and spend more time in the second mode than in the third mode.

[0035] For the nodes assigned the second role (non-router nodes), it is important to receive control commands in time so as to reduce the execution latency experienced on the control network. Therefore, it is preferred that the non-router nodes stay in the second mode longer than in the third mode.

[0036] Preferably, the nodes assigned the third role are further configured to operate in both the fourth mode and the fifth mode in a time-interleaved manner, and spend more time in the fourth mode than in the fifth mode.

[0037] For the nodes assigned the third role (data collector nodes), their main responsibility is to collect state information and / or sensing data from other nodes. Given that such information and / or data can be sent out by a single node at any time, it is beneficial for the data collector nodes to stay in the fourth mode to monitor the channel according to the second communication protocol for most of the time.

[0038] Advantageously, the wireless control system is used for lighting control, and / or for controlling sensors and collecting sensing data.

[0039] In a preferred setting, the wireless control system is used for lighting control, and it can also be used to collect status information and sensing data from actuators and sensors collocated with or located in the vicinity of the lamps. In another example, the wireless control system can also be a control system for building automation in an office or home, or a control system for industrial control in a factory.

[0040] In a preferred setting of the wireless control system, within one-hop direct link range of each node assigned the first role, at least one node of the plurality of nodes is assigned the third role, and at least one node of the plurality of nodes is assigned the second role, and wherein the at least one node assigned the second role is configured to receive control commands from the nodes assigned the first role in the second mode, and to send status information to the at least one node assigned the third role in the third mode.

[0041] The efficiency of the disclosed system comes from the combination of three independent roles that cooperate in a dense network, where each individual node in the network is assigned a single role. The router nodes construct a sparse multi-hop network according to a first communication protocol. Around each router node within direct link range, there is a local star network constructed by at least one non-router node and at least one data collector node. In a preferred setting, one node is assigned the third role, while the majority of the nodes in the direct link range of the router nodes are assigned the second role. Such an arrangement further improves the efficiency of the system in terms of reducing latency in delivering control commands, suppressing interference to the sparse multi-hop network, and reducing the overhead of sending data packets carrying status information and / or sensing data over the sparse multi-hop network.

[0042] Beneficially, the nodes of the plurality of nodes assigned the first role are selected to ensure that all nodes of the plurality of nodes are within one-hop range of at least one node assigned the first role.

[0043] The star network constructed around each router node with one-hop direct link is primarily to reduce interference and improve the performance of the system. In a large-scale wireless control system, it relies on the sparse multi-hop network to distribute control commands to and collect sensing data from the plurality of nodes, especially for the nodes at the edge of the network. Therefore, the router nodes are selected to ensure the connectivity of the system.

[0044] According to a second aspect of the application, a node is provided. The node of a plurality of nodes in a wireless control system, the node comprising a radio unit capable of operating according to both a first communication protocol capable of supporting a mesh or tree network with multi-hop routing and a second communication protocol capable of supporting a star network with point-to-point connections. The node further comprises a controller capable of controlling the node according to any of three roles, the controller being configured to control the node to perform an assigned role of the three roles, the three roles being:

[0045] - a first role, wherein the node is configured to operate in a first mode according to the first communication protocol, wherein the routing capability of the node is enabled, and the node is operable to distribute control commands to the plurality of nodes and to forward state information from the plurality of nodes via multi-hop routing;

[0046] - a second role, wherein the node is configured to operate in a second mode according to the first communication protocol, wherein the routing capability of the node is disabled, and the node is operable to receive control commands broadcast by another node of the plurality of nodes by means of a one-hop direct link; and in a third mode according to the second communication protocol, wherein the node is operable to send state information to one or more nodes of the plurality of nodes; and

[0047] - a third role, wherein the node is configured to operate in a fourth mode according to the second communication protocol, wherein the node is operable to receive state information from one or more nodes of the plurality of nodes by means of point-to-point connections; and in a fifth mode according to the first communication protocol, wherein the node is operable to send aggregated state information received from the one or more nodes in the fourth mode to a parent node of the plurality of nodes by means of a one-hop direct link; and wherein the parent node is a node assigned the first role or a node assigned the second role.

[0048] The radio unit can be a combined radio supporting both protocols, or a unit comprising two single-mode radios, each of which supports only one communication protocol. When the two single-mode radios operate in overlapping spectrum, it is beneficial to schedule the radio unit to operate according to the first or second wireless communication protocol in a time-interleaved manner.

[0049] According to another aspect of the application, a method of a wireless control system is provided. The method comprises the steps of operating a plurality of nodes according to at least one of a first communication protocol capable of supporting a mesh or tree network with multi-hop routing and a second communication protocol capable of supporting a star network with point-to-point connections. The method further comprises the steps of assigning one of three roles to each node of the plurality of nodes, and assigning each of the three roles to at least one node of the plurality of nodes, the three roles being:

[0050] - a first role, wherein the node operates in a first mode according to a first communication protocol, which first communication protocol enables routing capabilities for distributing control commands to a plurality of nodes via multi-hop routing and forwarding status information from the plurality of nodes;

[0051] - a second role, wherein the node operates in a second mode according to the first communication protocol, which first communication protocol disables routing capabilities for receiving control commands broadcasted by another one of the plurality of nodes by means of a one-hop direct link; and in a third mode according to a second communication protocol for sending status information to one or more of the plurality of nodes via a point-to-point connection; and

[0052] - a third role, wherein the node operates in a fourth mode according to the second communication protocol for receiving status information from one or more of the plurality of nodes by means of a point-to-point connection; and in a fifth mode according to the first communication protocol for sending aggregated status information received in the fourth mode from the one or more nodes to a parent node of the plurality of nodes by means of a one-hop direct link; and wherein the parent node is a node assigned the first role or a node assigned the second role.

[0053] According to a further aspect of the present application, a method of operating a node of a plurality of nodes in a wireless control system is provided. The method comprises a node:

[0054] - operating according to both a first communication protocol, which enables a mesh or tree network with multi-hop routing, and a second communication protocol, which enables a star network with point-to-point connections;

[0055] - when a first role is assigned to the node, executing the first role by operating in a first mode according to the first communication protocol, which first communication protocol enables routing capabilities for distributing control commands to a plurality of nodes via multi-hop routing and forwarding status information from the plurality of nodes;

[0056] - when a second role is assigned to the node, executing the second role by operating in a second mode according to the first communication protocol, which second communication protocol disables routing capabilities for receiving control commands broadcasted by another one of the plurality of nodes by means of a one-hop direct link; and in a third mode according to the second communication protocol for sending status information to one or more of the plurality of nodes via a point-to-point connection; and

[0057] - when the third role is assigned to the node, performing the third role by operating in a fourth mode according to the second communication protocol for receiving state information from one or more of the plurality of nodes by means of a point-to-point connection; and in a fifth mode according to the first communication protocol for transmitting aggregated state information received in the fourth mode from one or more of the plurality of nodes to a parent node of the plurality of nodes using a one-hop direct link; and wherein the parent node is a node assigned the first role or a node assigned the second role.

[0058] The application can be embodied in a computer program comprising code means, which when executed by a plurality of nodes each comprising processing means, cause the processing means comprised in the plurality of nodes to perform the method according to the application in a collective manner.

[0059] The application can be embodied in a computer program comprising code means, which when executed by a node comprising processing means, cause the processing means to perform the method according to the application. BRIEF DESCRIPTION OF DRAWINGS

[0060] In the drawings, like reference numerals are generally used to refer to same or similar elements throughout different views. Moreover, the drawings are not necessarily to scale, with emphasis instead generally being placed upon illustrating the principles of the application.

[0061] Figure 1 A wireless control system is shown with a plurality of nodes with high node density;

[0062] Figure 2 A wireless control system is shown, wherein each of the plurality of nodes in the wireless control system is assigned one of three roles;

[0063] Figure 3 A wireless control system is shown utilizing multi-hop communication over a sparse network according to a first communication protocol;

[0064] Figure 4 Communication in a star network around each node assigned the first role is depicted;

[0065] Figure 5 Basic components of a node of the plurality of nodes in the wireless control system are schematically depicted;

[0066] Figure 6 A flowchart of a method of the wireless control system is shown;

[0067] Figure 7 A flowchart of a method performed by a node of the plurality of nodes in the wireless control system is shown. DETAILED DESCRIPTION

[0068] Various embodiments of the present invention will now be described based on a wireless control system 100 comprising a plurality of nodes 500, as illustrated in Figure 1 The network can be a local network under control of a local coordinator 600 to serve a specific control purpose. The network can also be connected to a cloud or backbone network via a 600 gateway, bridge or router device. In a lighting environment, the nodes 500 can be comprised in lighting devices, luminaires, sensors, actuators such as switches to serve the communication function of the lighting device, luminaire, sensor or switch. The nodes 500 can also be comprised in remote controllers in an HVAC system, smart fridge, smart oven, other smart white goods, or more generally in a building / home automation environment.

[0069] Considering that a control system can comprise a large number of nodes, transmissions from those nodes can collide with each other, especially when they are deployed with a relatively high node density. A relatively high node density indicates that most nodes have more than one neighbor node within one-hop direct communication range. The present invention aims at improving the efficiency and reliability of large-scale data distribution and collection in a wireless control system.

[0070] To achieve this goal, the present invention proposes to assign a dedicated role to each of the plurality of nodes from three possible roles, as illustrated in Figure 2 For the first role, the node is configured to operate as a router node 200 in a first mode according to a first communication protocol, with enabled routing capabilities. The router node 200 is operable to distribute control commands to the plurality of nodes 500 and to forward state information from the plurality of nodes 500 via multi-hop routing. Thus, the router nodes build a sparse multi-hop network according to the first communication protocol, which acts as a kind of core network for the wireless control system. Around each router node with one-hop direct link, a local star network is built, as illustrated in Figure 2The dashed circle in the figure indicates a star-shaped network. The star-shaped network comprises at least a node assigned the second role as a non-router node 300, and at least a node assigned the third role as a data collector node 400. The non-router node 300 is configured to operate in the second mode according to the first communication protocol with the routing capability disabled, and the node is operable to receive control commands broadcasted by a router node having a one-hop direct link. The non-router node is further configured to operate in the third mode according to the second communication protocol to transmit state information and / or sensing data to the data collector node 400 via a point-to-point connection. The data collector node 400 is configured to operate in the fourth mode according to the second communication protocol to receive state information and / or sensing data from one or more nodes, which can be a router node 200 and / or multiple non-router nodes 300, with a point-to-point connection. To improve the efficiency of transmitting state information and / or sensing data, the data collector node 400 is configured to aggregate state information received from one or more nodes in a combined data packet. Assuming that the overhead of transmitting information such as packet headers is relatively fixed according to a particular communication protocol, it is more beneficial to maximize the payload portion of a single packet than to send multiple small packets each having the same packet header but a short payload.

[0071] Figure 3 Bidirectional multi-hop communication over a sparse network according to the first communication protocol is demonstrated. The sparse multi-hop network mainly comprises nodes assigned the first role or router nodes, and acts as the core network of the wireless control system. Thus, the router nodes carry the responsibility of guaranteeing the connectivity of the entire system, especially for nodes far away from the central controller or gateway. In view of the first communication protocol, by making the wireless control system sparse, mutual interference between neighboring nodes is significantly suppressed. The reduction of packet collisions and retransmissions improves the efficiency of the system in terms of both power consumption and latency.

[0072] Figure 4 An example of communication in a local star-shaped network around each node assigned the first role is depicted. The local star-shaped network is typically centered around a router node 200. Around the router node 200 within a one-hop direct link, there is at least one non-router node 300 and a data collector node 400. In a preferred setup of the star-shaped network, one node acts as the data collector node 400, and most nodes act as non-router nodes. Depending on the connectivity of the star-shaped network, it is also possible that each router node 200 has more than one data collector node 400 in order to guarantee good connectivity with all non-router nodes for collecting state information or sensing data.

[0073] In the star network, the non-router nodes 300 stay in the second mode according to the first communication protocol most of the time in order to detect control commands broadcast by the router node 200 in a timely manner. After a certain time period, the non-router nodes transmit their status information and / or collected sensing data to the data collector node according to the second communication protocol. The data collector node 400 monitors the channel for a further time interval according to the second communication protocol to detect packets from one or more nodes, which are mainly non-router nodes 300, but can also be router nodes 200. Then, the data collector node assembles a new packet with the aggregated status information and / or sensing data from other nodes and from itself, and then transmits the new packet to the parent node according to the first communication protocol. Assuming that such new packets are sporadically transmitted and can have a reduced transmission power level, the interference from the data collector node 400 to the sparse multi-hop network can be negligible.

[0074] As Figure 4 As indicated in the preferred setup, the router node 200 acts as a parent node for the data collector node 400, and the data collector node 400 transmits the aggregated status information and / or sensing data directly to the router node. Since the data collector node 400 stays in the fourth mode according to the second communication protocol most of the time, the data collector node 400 can occasionally poll its parent node (the router node) to receive control commands. The polling can be combined with the transmission of the aggregated status information and / or sensing data, and thus can reduce the number of switches between the first and second communication protocols. However, if certain types of control commands should comply with critical latency requirements, the data collector node 400 can have to poll the router node more frequently. Optionally, the router node 200 can forward control commands to the data collector node 400 in the sixth mode according to the second communication protocol. In another option, if additional security measures are taken to protect the communication according to the first communication protocol, the router node 200 can transmit a notification to the data collector node 400 in the sixth mode according to the second communication protocol, and then the data collector node 400 switches to the first communication protocol to poll the router node 200 upon receiving the notification from the router node 200. Alternatively, the router node 200 can broadcast / replay control commands according to the first communication protocol after a certain time interval since the transmission of the notification according to the second communication protocol. And thus, the data collector node 400 can only switch to the first communication protocol to listen to the broadcasted control commands.

[0075] Alternatively, the non-router node 300 can also act as a parent node for the data collector node 400. The non-router node 300 would then be responsible for the communication between the data collector node 400 and the sparse multi-hop network. Upon receiving a control command, the non-router node 300 can forward the control command directly in the third mode according to the second communication protocol. Again, if additional security measures are taken to protect the communication according to the first communication protocol, the non-router node 300 can only send a notification about the control command to the data collector node 400 and can then trigger the data collector node 400 to switch to the first communication protocol to poll the router nodes to receive the command. Similarly, the data collector node 400 sends the aggregated status information and / or sensing data to the non-router node 300 according to the first communication protocol, and the non-router node 300 can then forward the packets received from the data collector node to the router nodes according to the first communication protocol. In this case, the non-router node 300 acts as a relay node between the router node 200 and the data collector node 400, which is less efficient than the case where the data collector node 400 sends the aggregated status information and / or sensing data directly to the router nodes. However, it can still be beneficial in scenarios where the data collector node 400 is located relatively far away from the router node 200, where the link quality of the direct link to the router node is below a certain threshold, and by using the non-router node as a parent node for relaying, a lower transmission power can be used according to the first communication protocol. Thus, potential interference on multi-hop routing in the sparse network can be further reduced.

[0076] The first wireless communication protocol is mainly implemented for large-scale information distribution and collection in a wireless control system with multiple nodes, which can be used for lighting control and / or building automation. Importantly, the first wireless communication protocol supports multi-hop routing, which can be Zigbee, Thread, Bluetooth Mesh, Wi-Fi Mesh, WirelessHART, SmartRF, CityTouch, IP500, Z-wave, or any other mesh or tree-based technology.

[0077] Preferably, the second wireless communication protocol complies with the Bluetooth Low Energy, BLE, standard. It can also be Wi-Fi direct, Zigbee Inter-PAN, Zigbee Touchlink, or another wireless communication standard that facilitates a simple setup for point-to-point connections.

[0078] When the two communication systems according to the first and second communication protocols can use different frequency plans and time schedules, the multiple nodes are split between the two systems with specific roles assigned. Thus, the mutual interference between neighboring nodes can be significantly reduced.

[0079] Figure 5 The basic components of one of the nodes 200, 300, 400, 500 in the wireless control system 100 are schematically depicted. The nodes 200, 300, 400, 500 comprise a radio unit 510 capable of operating according to at least one or both of a first communication protocol capable of supporting a mesh or tree network with multi-hop routing and a second communication protocol capable of supporting a star network with point-to-point connections. The radio unit 510 can be a combined device 520 to support both the first and second communication protocols and operate in a time-interleaved fashion according to either of the two communication protocols. The radio unit 510 can comprise two independent single-mode transceivers 520, 530 and each support one communication protocol. The radio unit 510 can comprise at least a single-mode transceiver 520 to support the first communication protocol. The nodes 200, 300, 400, 500 further comprise a controller 540 configured to control the node to perform one of three roles assigned.

[0080] Optionally, the nodes 200, 300, 400, 500 can further comprise an application controller and / or actuator, as indicated by 550 in Figure 5 The application controller or actuator can be related to the control function of the node in a lighting environment or more generally in a building automation environment. The application controller and / or actuator can execute control commands received by the node. And status information is provided by the application controller and / or actuator as feedback to the control system.

[0081] In another option, the nodes 200, 300, 400, 500 can further comprise a sensor, as indicated by 560 in Figure 5 The sensor 560 can be configured to detect presence and / or environmental information, such as temperature, humidity, etc. The sensed data can be collected in addition to or independent of the status information of the node or the application controller and / or actuator.

[0082] Depending on the physical properties of a certain node, which can support only one communication protocol as a legacy device or both communication protocols as a more advanced combined device, only a subset or all three of the three roles can be assigned to the node.

[0083] Figure 6A flowchart of a method 700 of a wireless control system is shown. The method 700 comprises a step S701 of operating a node of a plurality of nodes according to at least one of a first communication protocol capable of supporting a mesh or tree network with multi-hop routing and a second communication protocol capable of supporting a star network with point-to-point connections. The method 700 further comprises a step S702 of assigning the node to one of three roles. In a step S703, it is checked whether the node is assigned the first role; if so, the method 700 comprises a step S704 of operating the node as a router node 200 and in a first mode, the router node operates according to the first communication protocol enabling routing capabilities for distributing control commands to the plurality of nodes via multi-hop routing and forwarding status information from the plurality of nodes. If the node is not assigned the first role, it is further checked in a step S705 whether the node is assigned the second role as a non-router node 300. If so, in a step S706, the node is configured to operate in a second mode according to the first communication protocol disabling routing capabilities for receiving control commands broadcasted by nodes having a one-hop direct link; and in a step S707, the node is configured to operate in a third mode according to the second communication protocol for transmitting status information via point-to-point connections. If the node is not assigned the second role, it is further checked in a step S708 whether the node is assigned the third role as a data collector node 400. If so, in a step S709, the node is configured to operate in a fourth mode according to the second communication protocol for receiving status information from one or more nodes having point-to-point connections; and in a step S710, the node is configured to operate in a fifth mode according to the first communication protocol for transmitting aggregated status information received from the one or more nodes in the fourth mode to a parent node with a one-hop direct link. The parent node of the data collector node 400 is preferably a router node 200, but can also be a non-router node 300. Figure 6 The example shown in Fig. 6 is merely exemplary, and another variant can be to make a single check to verify which role is assigned, instead of using the three sequential checks S703, S704 and S705.

[0084] Figure 7A flowchart of a method 800 carried out by one of the plurality of nodes in the wireless control system is shown. In step S801, the method 800 comprises the node operating according to both a first communication protocol capable of supporting a mesh or tree network with multi-hop routing and a second communication protocol capable of supporting a star network with point-to-point connections. In step S802, the method 800 further comprises the node performing an assigned role of the three roles. In step S803, it is checked whether the assigned role is a first role; if so, the method 800 comprises step S804 in which the node operates as a router node 200 and in a first mode, the router node operates according to the first communication protocol with routing capability enabled for distributing control commands to the plurality of nodes via multi-hop routing and forwarding status information from the plurality of nodes. If the assigned role is not the first role, as a non-router node 300, it is further checked in step S805 whether the assigned role is a second role. If so, in step S806, the node is configured to operate in a second mode according to the first communication protocol with routing capability disabled for receiving control commands broadcast by nodes with one-hop direct links; and in step S807, the node is configured to operate in a third mode according to the second communication protocol for transmitting status information via point-to-point connections. If the assigned role is not the second role, it is further checked in step S808 whether the assigned role is a third role, as a data collector node 400. If so, in step S809, the node is configured to operate in a fourth mode according to the second communication protocol for receiving status information from one or more nodes with point-to-point connections; and in step S810, the node is configured to operate in a fifth mode according to the first communication protocol for transmitting aggregated status information received from the one or more nodes in the fourth mode to a parent node with one-hop direct links. As Figure 6 the same, Figure 7 the examples shown in

[0085] Note that the methods as depicted in Figure 6 and Figure 7 may be performed recursively on a periodic basis, or repeatedly upon a triggering event, such as a failure of a single node, or a link quality degradation of a particular connection due to noise or interference, or a mobility of a particular node.

[0086] The method according to the present application can be implemented on a computer as a computer-implemented method, or in dedicated hardware, or in a combination of both.

[0087] Executable code of the method according to the present application can be stored on a computer / machine readable storage device. Examples of computer / machine readable storage devices include non-volatile memory devices, optical storage devices, solid-state media, integrated circuits, servers, etc. Preferably, the computer program product comprises non-transitory program code means stored on a computer readable medium for performing the method according to the present application, as disclosed in the above embodiments, when said program product is executed on a computer or processing means comprised in a node or network or commissioning device.

[0088] Methods, systems, and computer readable media (transitory and non-transitory) can also be provided to implement selected aspects of the above embodiments.

[0089] The term "controller" is used in this document generally to describe various apparatus related to, among other things, the operation of one or more network devices or coordinators. A controller can be implemented in numerous ways, e.g., such as with dedicated hardware, to perform various functions discussed herein. A "processor" is one example of a controller which employs one or more microprocessors that can be programmed using software (e.g., microcode) to perform various functions discussed herein. A controller can be implemented with or without employing a processor, and also can be implemented as a combination of dedicated hardware to perform some functions and a processor (e.g., one or more programmed microprocessors and associated circuitry) to perform other functions. Examples of controller components that can be employed in various embodiments of the present disclosure include, but are not limited to, a conventional microprocessor, a special purpose

[0090] In various implementations, a processor or controller can be associated with one or more storage media (generically referred to herein as "memory"), e.g., volatile and non-volatile computer memory such as RAM, PROM, EPROM, and EEPROM, compact disks, optical disks, etc. In some implementations, the storage media can be encoded with one or more programs that, when executed on one or more processors and / or controllers, perform at least some of the functions discussed herein. Various storage media can be fixed within a processor or controller or can be transportable, such that the one or more programs stored thereon can be loaded into a processor or controller so as to implement various aspects of the present application discussed herein. The terms "program" or "computer program" are used herein in a generic sense to refer to any type of computer code (e.g., software or microcode) that can be employed to program a processor or controller.

[0091] The term "network" as used herein refers to any interconnection of two or more devices (including controllers or processors) that facilitates the transfer of information (e.g., for device control, data storage, etc.) between any two or more devices and / or among multiple devices coupled to the network.

Claims

1. A wireless control system (100), comprising: - Multiple nodes (500) are configured to operate according to at least one of the following: • A first communication protocol capable of supporting mesh or tree networks with multi-hop routing; • Capable of supporting a second communication protocol for star networks with point-to-point connections; Furthermore, each of the plurality of nodes (500) is assigned one of three roles (200, 300, 400), and each of the three roles is assigned to at least one of the plurality of nodes (500), wherein the three roles (200, 300, 400) are: - First role (200), wherein the node is configured to operate in a first mode according to a first communication protocol, wherein the node’s routing capability is enabled, and the node is operable to distribute control commands to multiple nodes via multi-hop routing and forward status information received from multiple nodes; - Second role (300), wherein the node is configured as follows: o operates in a second mode according to a first communication protocol, wherein the routing capability of the node is disabled, and the node is operable to receive control commands broadcast by another node among a plurality of nodes via a one-hop direct link; and o operates in a third mode according to a second communication protocol, wherein the node is operable to send status information to one or more of a plurality of nodes; as well as - Third role (400), wherein the node is configured as either of the following two o operates in a fourth mode according to a second communication protocol, wherein the node is operable to receive status information from one or more of a plurality of nodes by means of a point-to-point connection; and o operates in a fifth mode according to a first communication protocol, wherein the node is operable to send, via a one-hop direct link, aggregation state information received from one or more nodes in a fourth mode to a parent node among a plurality of nodes; and wherein the parent node is a node assigned a first role or a node assigned a second role.

2. The wireless control system (100) according to claim 1, wherein each of the plurality of nodes (500) can be assigned any one of three roles (200, 300, 400).

3. The wireless control system (100) according to claim 1 or 2, wherein, The nodes in the plurality of nodes (500) that have been assigned a second role (300) are further configured to operate in a third mode when a control command is received in the second mode, in which case the received control command is forwarded to the nodes in the plurality of nodes (500) that have been assigned a third role (400) via a point-to-point connection.

4. The wireless control system (100) according to claim 1 or 2, wherein, The nodes (500) among the multiple nodes (300) assigned to the second role are further configured to operate in the third mode when a control command is received in the second mode, at which time a notification is sent to the nodes (500) among the multiple nodes (400) assigned to the third role (400) via a point-to-point connection.

5. The wireless control system (100) according to claim 4, wherein the node among the plurality of nodes (500) assigned the third role (400) is further configured to operate in the fifth mode according to the first communication protocol upon receiving the notification, in which case the parent node is polled to receive the control command.

6. The wireless control system (100) according to claim 1 or 2, wherein, The nodes (500) among the plurality of nodes assigned a first role (200) are further configured to operate in a sixth mode according to a second communication protocol when sending status information to one or more of the plurality of nodes.

7. The wireless control system (100) according to claim 1 or 2, wherein, The nodes (500) among the multiple nodes assigned the second role (300) are further configured to operate in a time-interleaved manner under both the second and third modes, with the time spent in the second mode being longer than the time spent in the third mode.

8. The wireless control system (100) according to claim 1 or 2, wherein, The nodes (500) among the multiple nodes assigned the third role (400) are further configured to operate in a time-staggered manner under both the fourth and fifth modes, with the time spent in the fourth mode being longer than the time spent in the fifth mode.

9. The wireless control system (100) according to claim 1 or 2, wherein the wireless control system (100) is used for lighting control and / or for controlling sensors and collecting sensing data.

10. The wireless control system (100) according to claim 1 or 2, wherein, Within a one-hop direct link range of each node assigned a first role (200), at least one of the plurality of nodes (500) is assigned a third role (400), and at least one of the plurality of nodes (500) is assigned a second role (300), wherein at least one node assigned a second role (300) is configured to receive control commands from the node assigned a first role (200) in a second mode, and to send status information to at least one node assigned a third role (400) in a third mode.

11. The wireless control system (100) according to claim 10, wherein a node among the plurality of nodes (500) assigned a first role (200) is selected to ensure that all nodes among the plurality of nodes (500) are within one hop of at least one node assigned the first role (200).

12. A node in a plurality of nodes (500) of a wireless control system (100), said node comprising: -A radio unit (510) capable of operating according to the following two conditions. • Capable of supporting the first communication protocol for mesh or tree networks with multi-hop routing, and • Capable of supporting a second communication protocol for star networks with point-to-point connections; - A controller (540) capable of controlling a node according to any one of three roles (200, 300, 400), the controller being configured to control the node to perform an assigned role among the three roles (200, 300, 400), the three roles (200, 300, 400) being: - First role (200), wherein the node is configured to operate in a first mode according to a first communication protocol, wherein the node's routing capabilities are enabled, and the node is operable to distribute control commands to the plurality of nodes via multi-hop routing and forward status information from the plurality of nodes (500); - Second role (300), wherein the node is configured as either of the following o operates in a second mode according to a first communication protocol, wherein the routing capability of the node is disabled and the node is operable to receive control commands broadcast by another node among a plurality of nodes (500) via a one-hop direct link. and o operates in a third mode according to a second communication protocol, wherein the node is operable to send status information to one or more of the plurality of nodes (500); as well as - Third role (400), wherein the node is configured as either of the following two o operates in a fourth mode according to a second communication protocol, wherein the node is operable to receive status information from one or more nodes by means of a point-to-point connection; and o operates in a fifth mode according to a first communication protocol, wherein the node is operable to send aggregation state information received from the one or more nodes in a fourth mode to a parent node among the plurality of nodes (500) via a one-hop direct link; and wherein the parent node is a node assigned a first role (200) or a node assigned a second role (300).

13. A method (700) for operating a wireless control system (100) comprising a plurality of nodes (500), the method comprising the steps of: The plurality of nodes (500) shall be operated (S701) according to at least one of a first communication protocol capable of supporting a mesh or tree network with multi-hop routing and a second communication protocol capable of supporting a star network with point-to-point connections. The method further includes the following steps: assigning one of three roles (200, 300, 400) to each of the plurality of nodes (500), and assigning each of the three roles (200, 300, 400) to at least one of the plurality of nodes (500), wherein the three roles (200, 300, 400) are: -(S703) First role (200), where nodes o operates in a first mode (S704) according to a first communication protocol, wherein the first communication protocol enables routing capabilities for distributing control commands to the plurality of nodes (500) via multi-hop routing and forwarding status information from the plurality of nodes (500); -(S705) Second role (300), where nodes o operates in the second mode (S706) according to a first communication protocol, wherein the first communication protocol disables routing capabilities for receiving control commands broadcast by another node of the plurality of nodes (500) via a one-hop direct link; and o operates in the third mode (S707) according to the second communication protocol, for sending status information to one or more of the plurality of nodes; and -(S708) Third role (400), where nodes o operates in the fourth mode (S709) according to the second communication protocol, for receiving status information from one or more of the plurality of nodes (500) by means of a point-to-point connection; and o operates in the fifth mode (S710) according to the first communication protocol, for sending aggregation state information received from the one or more nodes in the fourth mode to the parent node among the plurality of nodes (500) via a one-hop direct link; and wherein the parent node is a node assigned a first role (200) or a node assigned a second role (300).

14. A method (800) for operating a node among a plurality of nodes (500) in a wireless control system (100), the method comprising the node: - Operate according to both a first communication protocol that can support mesh or tree networks with multi-hop routing and a second communication protocol that can support star networks with point-to-point connections (S801); - When the first role (200) is assigned to a node (S803), the first role (200) is executed as follows. Operating in the first mode (S804) according to the first communication protocol, the first communication protocol enables routing capabilities for distributing control commands to the plurality of nodes (500) via multi-hop routing and forwarding status information from the plurality of nodes (500); - When the second role (300) is assigned to a node (S805), the second role (300) is executed through the following two methods. o operates in the second mode (S806) according to the first communication protocol, wherein the first communication protocol disables routing capabilities for receiving control commands broadcast by another node among the plurality of nodes (500) via a one-hop direct link; and o Operates in the third mode (S807) according to the second communication protocol, for sending status information via a point-to-point connection; and - When the third role (400) is assigned to a node (S808), the third role (400) is executed as follows. o operates in the fourth mode (S809) according to the second communication protocol, for receiving status information from one or more of the plurality of nodes (500) by means of a point-to-point connection; and o operates in the fifth mode (S810) according to the first communication protocol, for sending the aggregation state information received from one or more of the plurality of nodes (500) in the fourth mode to the parent node of the plurality of nodes using a one-hop direct link; and wherein the parent node is a node assigned a first role (200) or a node assigned a second role (300).

15. A computer program product including code means, when the computer program product is executed by a plurality of nodes (500), each including a processing means, the code means causing the processing means included in the plurality of nodes (500) to collectively perform the method (700) of claim 13.

16. A computer program product including code means, wherein when the computer program product is executed by a node including a processing means, the code means causes the processing means to perform the method (800) of claim 14.

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