Method for migrating nodes in a distributed network to a centralized network - Patent Application 20070122997

Abstract

A method (500) for migrating two or more nodes (400) in a distributed wireless network to a centralized wireless network, the method (500) including: a step (S501) of receiving configuration information about the distributed wireless network from a second bridge device (300) in the distributed wireless network by a first bridge device (200); a step (S502) of accessing the distributed wireless network by the first bridge device (200) based on the received configuration information; a step (S503) of querying two or more nodes (400) in the distributed wireless network by the first bridge device (200) to collect topology information between the two or more nodes (400); a step (S504) of determining, by the first bridge device (200) based on the topology information, a sequence list for requesting the two or more nodes (400) to join the centralized wireless network; and a step (S505) of notifying the two or more nodes (400) to join the centralized wireless network according to the sequence list.

Description

[Technical Field]

[0001] The present invention relates to the field of wireless communications. In particular, various methods, apparatus, and systems related to transitioning a node between two different wireless networks are disclosed herein. [Background technology]

[0002] Zigbee, Thread, and Bluetooth Mesh are examples of wireless networks targeted at IoT applications such as lighting and building automation. They offer low-latency, low-rate services that allow messages to be passed between, for example, a light switch and one or more lighting fixtures. Mesh networking offers great flexibility and scalability to the system. However, centralized Zigbee networks offer improved network control and security, making them attractive in many applications. Thus, there is a need to reliably migrate existing decentralized networks to centralized networks.

[0003] Some communication standards, such as the Zigbee standard, support both distributed and centralized network architectures. Such standards may also define how distributed and centralized networks can be formed from scratch. However, there is no clearly defined way to move an existing distributed network to a centralized network without having to redeploy the entire network. Furthermore, it may be desirable for the transition to be performed on-the-fly, with reduced impact on network functionality. Summary of the Invention [Problem to be solved by the invention]

[0004] In a distributed network, some nodes are end nodes or leaf nodes that rely on other nodes (router nodes or parent nodes) to relay messages to them. One problem can occur during the transition from a distributed network to a centralized network: if a router node or parent node leaves the distributed network before the end nodes and / or leaf nodes, the end nodes and / or leaf nodes may lose their connection to the distributed network and become unreachable without being informed of the transition. [Means for solving the problem]

[0005] It has been recognized by the inventors that it would be beneficial to regulate network migration procedures taking topology information into account. Among other things, the object of the present invention is achieved by a method according to claim 1 and a bridge device according to claim 11.

[0006] According to a first aspect of the present invention, there is provided a method for transitioning two or more nodes in a distributed wireless network to a centralized wireless network, the method including the steps of: receiving, by a first bridge device, configuration information regarding the distributed wireless network from a second bridge device in the distributed wireless network, accessing the distributed wireless network by the first bridge device based on the received configuration information, querying two or more nodes in the distributed wireless network by the first bridge device to collect topology information between the two or more nodes, determining, by the first bridge device, a sequence list for requesting the two or more nodes to join the centralized wireless network based on the topology information, and informing the two or more nodes to join the centralized wireless network according to the sequence list, wherein the sequence list is arranged such that when a first node of the two or more nodes receives a message from another bridge device via relay of a second node of the two or more nodes in the distributed wireless network, the first node allows the first node to join the centralized wireless network earlier than the second node.

[0007] The configuration information for the distributed wireless network may relate to a network ID of the distributed network, an operating channel of the distributed network, or another network parameter associated with the distributed network. The configuration information is used to assist the first bridge device in accessing the distributed network.

[0008] Topology information may be gathered by obtaining neighboring information associated with individual nodes, such as a list of neighbors with which it has a one-hop direct link, the output power used to establish a link with a neighbor node, the received power from a neighbor node, or link quality information associated with a link with another node.

[0009] Thus, topology information may relate to the physical deployment of nodes within a system. Topology information may also relate to the network construction of a distributed network, such as which nodes are assigned as router nodes and which nodes are assigned as end nodes or non-routing nodes. For example, an end node may receive information from a router node but not from another end node.

[0010] In a preferred embodiment, the sequence list is ordered such that if a first node of two or more nodes receives a message from a bridge device via relay of a second node of the two or more nodes in the distributed wireless network, the first node is allowed to join the centralized wireless network sooner than the second node.

[0011] The sequence list is ordered to avoid a situation where a critical node, e.g., a node that is the only link between two subparts of the network, moves to the new centralized network earlier than other nodes, causing some nodes in the distributed network to become unreachable in order to announce this transition. For example, a router node or parent node will leave the distributed network later than an end node or child node that is dependent on the router node or parent node to gain access to the distributed network.

[0012] Advantageously, the method further comprises the step of opening, by the first bridge device, the centralized wireless network for nodes to join.

[0013] This step may be performed by the first bridge device before or after joining the distributed wireless network, depending on whether the first bridge device can be in two networks simultaneously, such as via two radios or via a single radio in a time-sharing manner. Alternatively, the first bridge device may open the centralized wireless network after notifying two or more nodes to join the centralized wireless network. Also, the first bridge device may notify two or more nodes to join after a delay that allows the centralized wireless network to prepare the nodes for joining.

[0014] Beneficially, the method further comprises providing, by the second bridge device, information relating to the two or more nodes to the first bridge device.

[0015] The second bridge device may provide information related to the individual nodes to the first bridge device to further assist the first bridge device in setting up the centralized network and establishing connections with the individual nodes.

[0016] Alternatively, the method further includes interrogating, by the first bridge device, two or more nodes on the distributed wireless network to collect information related to the two or more nodes.

[0017] Upon joining the distributed network, the first bridge device may collect such information itself, however, since the second bridge device may already have collected such information during normal data communication in the distributed network, it may be more efficient for such information to be provided directly by the second bridge device to the first bridge device.

[0018] In one example, the information associated with the two or more nodes includes at least one of addresses, configuration parameters, and state information associated with the two or more nodes.

[0019] Advantageously, the method further includes providing, by the first bridge device, one or more parameters relating to the centralized wireless network to the two or more nodes.

[0020] This step may be combined with the step of requesting two or more nodes to join the centralized wireless network.

[0021] The one or more parameters may relate to a network ID of the centralized network, an operating channel of the centralized network, or another network parameter.

[0022] In one example, the method further includes restoring a node of the two or more nodes in the centralized wireless network to a state of the node in a previous distributed wireless network.

[0023] By knowing the configuration, settings, state, or scene of each individual node within the distributed network, the first bridge device or the new bridge device may restore the node to its previous configuration, settings, state, or scene after the node moves to the new centralized network, which further enhances a smooth transition.

[0024] In another example, the method further includes generating a link key for a node of two or more nodes in the centralized wireless network based on information obtained related to the two or more nodes, and informing the node of the link key.

[0025] Upon receiving information related to an individual node, such as a node's identifier or address, an end-to-end link key may be generated by the first bridge device for that individual node, which may be used to increase security of end-to-end communications in the centralized network.

[0026] This step may be performed by a first bridge device of the centralized network, such that the first bridge device informs individual nodes about their dedicated link keys.

[0027] Advantageously, at least one of the distributed wireless network and the centralized wireless network conforms to the Zigbee standard.

[0028] The Zigbee standard has been widely adopted in home automation and lighting control applications. The Zigbee network layer natively supports both star and tree networks, as well as popular mesh networking. Powerful topology control provides great flexibility in control systems, especially for reaching destination nodes far away from the source node with direct links.

[0029] ZigBee defines three different device types: ZigBee Coordinator (ZC), ZigBee Router (ZR), and ZigBee End Device (ZED). These three devices fulfill different roles within a ZigBee network. ZigBee Router (ZR) passes data between the coordinator and / or devices. ZigBee End Device (ZED) provides only basic functionality. ZEDs are leaf nodes. ZEDs communicate only through their parent node and, unlike router devices, cannot relay messages intended for other nodes. ZEDs do not participate in routing. End devices rely on their parent router to send and receive messages. With respect to IEEE 802.15.4, ZCs and ZRs are fully functional devices (FFDs), and ZEDs are reduced function devices (RFDs).

[0030] Thus, topology information between two or more nodes in a distributed wireless network may be jointly determined by the physical locations of the nodes, the functionality supported by the nodes, and the type of role the nodes play in the distributed network.

[0031] Optionally, the first bridge device and the second bridge device are physically co-located. For example, the first bridge device and the second bridge device may be deployed close to each other, such as within direct wireless communication range. The first bridge device and the second bridge device may also be co-located such that the first bridge device should be replaced by the second bridge device after the migration. Physically, the first bridge device and the second bridge device may be the same bridge device. This also applies to a situation where an existing bridge device has the capability to transition to a centralized network through a firmware update. All these steps are simply performed on the same bridge device to migrate the network from a distributed topology to a centralized topology.

[0032] Advantageously, the first bridge device and the second bridge device have a further communication channel connecting them to each other, which does not belong to either the distributed or the centralized wireless network.

[0033] The further communication channel may be either a wired channel or a wireless channel. For example, the first bridge device and the second bridge device may be connected via an IP network, such as Ethernet. Alternatively, the first bridge device and the second bridge device may be connected via a Wi-Fi network, a BLE link, or a 4G / 5G cellular link.

[0034] According to a second aspect of the present invention, there is provided a bridge device for use in transitioning two or more nodes in a distributed wireless network to a centralized wireless network, the bridge device including: a communication interface configured to receive configuration information regarding the distributed wireless network from another bridge device in the distributed wireless network; a radio configured to access the distributed wireless network based on the received configuration information and to query two or more nodes in the distributed wireless network to collect topology information between the two or more nodes; and a controller configured to determine a sequence list for requesting the two or more nodes to join the centralized wireless network based on the topology information, wherein the radio is further configured to notify the two or more nodes to join the centralized wireless network according to the sequence list, and the sequence list is ordered such that when a first node of the two or more nodes receives a message from another bridge device via relay of a second node of the two or more nodes in the distributed wireless network, the first node can join the centralized wireless network earlier than the second node.

[0035] The entire procedure for migrating a node to a centralized network may be initiated, for example, by a new bridge device in the centralized network first requesting to join the existing distributed network by obtaining configuration parameters from the old bridge device in the distributed wireless network. Thereafter, the existing bridge device in the distributed wireless network or the new bridge device in the centralized network may take primary responsibility for arranging a smooth transition. In a preferred example, the new bridge device performs the main steps in the procedure.

[0036] The topology information is used to determine a sequence list to ensure that no unreachable nodes remain in the distributed network during the transition. The topology information may be collected by the new bridge device by querying nodes in the distributed network. Alternatively, the existing bridge device may collect topology information periodically during earlier data communication in the distributed network, and then the existing bridge device may provide such topology information directly to the new bridge device. Based on the topology information, the new bridge device determines a sequence list and requests nodes to join the centralized network according to the sequence list.

[0037] The existing bridge device may also provide additional information related to individual nodes, such as addresses, configuration parameters, the state of the node within the distributed network, etc. Such information may help the new bridge device restore the node to its previous state or configuration after the node moves to the new centralized network. The information may also be used to generate dedicated link keys to secure the end-to-end communication link.

[0038] Beneficially, the sequence list is ordered such that if a first node of the two or more nodes receives a message from another bridge device via relay of a second node of the two or more nodes in the distributed wireless network, the first node is allowed to join the centralized wireless network sooner than the second node.

[0039] In one option, the radio is further configured to open the centralized wireless network for nodes to join after notifying two or more nodes to join the centralized wireless network according to the sequence list.

[0040] In this option, the first bridge device opens the centralized wireless network after notifying two or more nodes to join the centralized wireless network. Thus, the first bridge device notifies two or more nodes to join after a delay that allows the centralized wireless network to prepare for the nodes to join.

[0041] In another option, the radio is further configured to open a centralized wireless network for the node and to operate in both the centralized wireless network and the distributed wireless network in a time-sharing manner.

[0042] As mentioned above, the first bridge device may open the centralized wireless network before initiating the transition procedure. This may be accomplished if the first bridge device can reside in the distributed network and the centralized network simultaneously, such as by incorporating two radios in the first bridge device or by using a single radio in the first bridge device in a time-sharing manner between the two networks. [Brief explanation of the drawings]

[0043] In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. [Figure 1] A possible system setup is shown. [Figure 2] 1 illustrates a flowchart of a method for migrating two or more nodes in a distributed wireless network to a centralized wireless network. [Figure 3] 1 shows a block diagram of a bridge device for use in a distributed wireless network. [Figure 4] An example of a bridge device is shown below. DETAILED DESCRIPTION OF THE INVENTION

[0044] The embodiments described 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 present disclosure and will recognize applications of these concepts not specifically addressed herein. It is understood that these concepts and applications fall within the scope of the present disclosure.

[0045] For wireless communications, a distributed network topology offers increased flexibility and scalability. However, it also poses security risks. Taking Zigbee as an example, there are well-known weaknesses in distributed Zigbee networks, especially during the joining process. To provide better security, it is attractive to move to a centralized network with additional secure joining mechanisms. Although the Zigbee standard defines how distributed and centralized networks can be formed from scratch, there is no clearly defined way to migrate an existing distributed network to a centralized network without having to redeploy the entire network. From a user experience perspective, it is important to be able to make this transition with minimal user intervention and minimal disruption to the network. Preferably, the transition can be performed on the fly.

[0046] One way is to use the Zigbee Commissioning Cluster (ZCC). ZCC essentially defines a message that can be sent to individual nodes in a network that contains information such as the Zigbee PAN-ID, extended PAN ID, network key, and link key of the centralized network to join. ZCC also defines a message that instructs the node to restart and join the new network. Upon restart, the node joins the new network using the more secure centralized joining mechanism defined in Zigbee and is also "aware" that it is now part of the centralized network.

[0047] Another approach is to define customized messages that essentially do a subset of what ZCC does. In its simplest form, a simple restart and rejoin message may be sent to a node that will cause the node to search for a new network, find the centralized network, and join the centralized network.

[0048] Regardless of the method used, nodes need to be nudged to leave the existing decentralized network to join the new centralized network. Known methods have shown how to move a single node from a decentralized network to a centralized network. However, a process / method for reliably transitioning all nodes in a network to a centralized network is still lacking. As an example, if a critical node, e.g., a node that is the only link between two subparts of the network, moves to the new centralized network before other nodes, a problem may arise in which some nodes will be made unreachable in the decentralized network to announce this transition. A workaround is for the extended PAN-ID, PAN-ID, network key, etc. to remain the same in both the existing decentralized network and the new centralized network. However, such a workaround may lead to unexpected confusion for nodes.

[0049] The present invention addresses the problem in a more generalized way, where a centralized network can become completely independent with fresh network parameters such as PAN-ID, network key, etc. This also provides improved security, as a new centralized network can freely choose fresh new keys, and thus starts as if it was built from scratch.

[0050] Figure 1 shows a possible system setup of an existing bridge device and a new bridge device. In this example, the new bridge device may be located remotely from the existing bridge device and is connected via an additional communication channel that does not belong to either the distributed network or the centralized network. The additional communication channel may follow a wireless or wired communication protocol.

[0051] According to the Zigbee protocol, the conventional mechanism for migrating nodes from an existing distributed network to a new centralized network is to communicate the existing Zigbee network parameters (PAN-ID, network key, etc.) and other information related to the distributed network to the new bridge device 200. This information may be encrypted and communicated between the existing bridge device 300 and the new bridge device 200 over a wired connection, such as over an IP network, or over a wireless connection. The wireless connection may be based on another wireless communication protocol, such as Wi-Fi, BLE, or 4G / 5G cellular, that is different from both the existing distributed network and the new centralized network.

[0052] 1 also highlights that problems can arise if the existing bridge device 300 natively instructs nodes (A-E) to sequentially switch to join the new bridge device 200 in centralized mode (by issuing a Zigbee commissioning cluster command or a simpler custom command): if node C leaves the distributed network, nodes D and E will no longer be reachable.

[0053] Therefore, a new scheme is needed to solve this problem. To help a new bridge device join the distributed network, the existing bridge device may send the network parameters related to the distributed network (PAN-ID, Extended PAN-ID, channel, network key, etc.) to the new bridge device directly via a communication interface. It may also be possible for the existing bridge device to keep the distributed network open for any node to join. Optionally, the existing bridge device may also send in this step a list of node identifiers or addresses (e.g., IEEE addresses), their existing / current settings / states / status (e.g., in case of lighting fixtures, it may be on / off state, color temperature status, etc.) to the new bridge device. As an example for implementing the proposed solution, the steps involved may be as follows:

[0054] a) Thus, the new bridge device 200 may perform a normal join (if the existing bridge device 300 has opened the network for joining) or a secure join (if the existing bridge device 300 has already provided the network parameters relevant to the distributed network). At the end of this step, the new bridge device 200 joins the existing distributed network.

[0055] b) The new bridge device 200 may ping different nodes for topology information based on the list of identifiers / addresses received in step a). The new bridge device 200 may also broadcast queries to nodes in the distributed network to collect topology information. The topology information may include the node's links / neighbors, transmit / receive power, etc. Based on the topology information, the existing bridge device 300 or the new bridge device 200 can derive an overview of the network topology between multiple nodes. If the new bridge device 200 receives the list of identifiers / addresses in step a), based on the responses from the nodes, the new bridge device 200 may derive whether there are any nodes that cannot be reached. This is a useful by-product and may help the user recognize that the location of the new bridge device 200 is not optimal considering the physical layout of the system.

[0056] c) The new bridge device 200 may randomly select a PAN-ID, an extended PAN-ID, an operating frequency channel, a network key, or other network parameters for the centralized network it forms.

[0057] d) The new bridge device 200 may derive a sequence list based on the topology information collected in step b). The new bridge device 200 may then request nodes to leave the existing distributed network according to the sequence list. As an example, in the topology shown in FIG. 1, the new bridge device 200 first asks valves A and D to leave, followed by valve C, then valves B and E. This order will ensure that all nodes in the network receive a request to leave the existing network. Before issuing the request or in combination with the request, the new bridge device 200 may send the network parameters selected in step c) to the nodes (one option, if implemented, is to send via the use of ZCC messages).

[0058] e) Once all nodes have been sent a request, or a ZCC message, or another customized message for the same purpose, the new bridge device 200 leaves the distributed network and forms a centralized network using the parameters selected in step d). The new bridge device 200 then opens the centralized network for nodes to join. The new bridge device 200 utilizes the information obtained in the previous step to successfully join the nodes in centralized mode. For example, when the new bridge device 200 receives information related to the nodes in step a) from the existing bridge device 300, it may be useful to obtain information derived from the installation code, possibly from a backend server, to obtain link keys for successfully joining these nodes to the centralized network.

[0059] f) Some radio chip vendors may offer a feature that allows a node to be part of two networks simultaneously. The new bridge device 200 may have this feature. In this case, since the bridge device can be on two separate networks, it may issue a leave request to the decentralized network while simultaneously accepting its own participation in the centralized network.

[0060] g) Optionally, once all nodes have joined the centralized network, the new bridge device 200 may use the information relating to the nodes obtained in step a) to return the nodes to the states they were in previously (on / off states, color temperature states, etc.).

[0061] 2 shows a flowchart of a method 500 for migrating two or more nodes in a distributed wireless network to a centralized wireless network. The method 500 includes, in step S501, receiving, by a first bridge device 200, configuration information about the distributed wireless network from a second bridge device 300 in the distributed wireless network; in step S502, accessing the distributed wireless network by the first bridge device 200 based on the received configuration information; in step S503, querying two or more nodes 400 in the distributed wireless network by the first bridge device 200 to collect topology information between the two or more nodes 400; in step S504, determining, by the first bridge device 200 based on the topology information, a sequence list for requesting the two or more nodes 400 to join the centralized wireless network; and in step S505, notifying the two or more nodes 400 to join the centralized wireless network according to the sequence list.

[0062] 3 shows a block diagram of bridge device 200. As a basic setup, bridge device 200 includes a communication interface 210, a radio 220, and a controller 230. Communication interface 210 is configured to receive configuration information about the distributed wireless network from other bridge devices in the distributed wireless network. Radio 220 is configured to access the distributed wireless network based on the received configuration information and to query two or more nodes 400 in the distributed wireless network to collect topology information between the two or more nodes 400. Controller 230 is configured to determine a sequence list for requesting two or more nodes 400 to join the centralized wireless network based on the topology information. The radio is further configured to notify two or more nodes 400 to join the centralized wireless network according to the sequence list.

[0063] As an example, the present invention may be implemented by a network forwarding module in a bridge device, as shown in FIG. 4 . The network forwarding module may be realized in a controller of the bridge device. In the new bridge device 200, the network forwarding module may obtain configuration information related to the existing distributed network from the existing bridge device 300 in step a) above. Accordingly, the network forwarding module may control the radio of the new bridge device 200 to perform steps a-b), such as joining the distributed network and querying nodes for topology information. It may also be possible for the network forwarding module to obtain topology information from the existing bridge device 300, which has already collected such information during periodic communication with the nodes. Based on the collected topology information, the network forwarding module performs calculations in step d) to generate an appropriate sequence list for migrating nodes to the new bridge device. Thereafter, the network forwarding module continues to monitor the radio to send requests to all nodes on the distributed network according to the determined sequence list. Once all requests have been sent, the network forwarding module controls the radio to switch from the distributed network to the new centralized network and wait for nodes to join.

[0064] Note that the present invention equally applies to situations where an existing bridge device has the transition capability to a centralized network via a firmware update, it is just that all these steps are performed on the same bridge device to move its network from a distributed to a centralized topology.

[0065] The method according to the invention may be performed on a computer as a computer implemented method, or may be performed on dedicated hardware, or may be performed as a combination of both.

Claims

1. 1. A method for migrating two or more nodes in a distributed wireless network to a centralized wireless network, the method comprising: receiving, by a first bridge device, configuration information for the distributed wireless network from a second bridge device in the distributed wireless network; accessing the distributed wireless network by the first bridge device based on the received configuration information; querying the two or more nodes in the distributed wireless network by the first bridge device to collect topology information between the two or more nodes; determining, by the first bridge device, a sequence list for requesting the two or more nodes to join the centralized wireless network based on the topology information; notifying the two or more nodes to join the centralized wireless network according to the sequence list; Including, the sequence list is ordered to allow a first node of the two or more nodes to join the centralized wireless network earlier than a second node of the two or more nodes when the first node receives a message from a bridge device via relay of the second node of the two or more nodes in the distributed wireless network.

2. The method comprises: opening, by the first bridge device, the centralized wireless network for nodes to join; The method of claim 1 , comprising:

3. The method comprises: providing, by the second bridge device, information relating to the two or more nodes to the first bridge device; The method of claim 1 , comprising:

4. The method comprises: interrogating, by the first bridge device, the two or more nodes on the distributed wireless network to collect information related to the two or more nodes; The method of claim 1 , comprising:

5. The method of claim 3 or 4, wherein the information associated with the two or more nodes includes at least one of addresses, configuration parameters, and state information associated with the two or more nodes.

6. The method comprises: providing, by the first bridge device, one or more parameters related to the centralized wireless network to the two or more nodes; 5. The method of claim 2, comprising:

7. The method comprises: restoring a node of the two or more nodes in the centralized wireless network to its state previously in the distributed wireless network; 5. The method of claim 3, comprising:

8. The method comprises: generating link keys for nodes of the two or more nodes in the centralized wireless network based on information obtained relating to the two or more nodes; and Informing the node about the link key; 5. The method according to claim 3, comprising the steps of:

9. The method of claim 1 , wherein at least one of the distributed wireless network and the centralized wireless network conforms to the Zigbee standard.

10. The method of claim 1 , wherein the first bridge device and the second bridge device have a further communication channel connecting to each other, the further communication channel not belonging to the distributed wireless network or the centralized wireless network.

11. 1. A bridge device for use in transitioning two or more nodes in a distributed wireless network to a centralized wireless network, the bridge device comprising: a communications interface configured to receive configuration information about the distributed wireless network from other bridge devices in the distributed wireless network; accessing the distributed wireless network based on the received configuration information; and querying the two or more nodes in the distributed wireless network to collect topology information between the two or more nodes; a radio configured to determining a sequence list for requesting the two or more nodes to join the centralized wireless network based on the topology information; a controller configured to: Including, the radio is configured to notify the two or more nodes to join the centralized wireless network according to the sequence list; a bridge device, wherein the sequence list is arranged such that when a first node of the two or more nodes receives a message from the other bridge device via relay of a second node of the two or more nodes in the distributed wireless network, the first node is allowed to join the centralized wireless network earlier than the second node.

12. 12. The bridge device of claim 11, wherein the radio is configured to open the centralized wireless network for nodes to join after notifying the two or more nodes to join the centralized wireless network according to the sequence list.

13. 12. The bridge device of claim 11, wherein the radio is configured to open the centralized wireless network for nodes and to operate in a time-sharing manner in both the centralized wireless network and the distributed wireless network.

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