Method for migrating nodes in distributed network to centralized network

Abstract

A method (500) for migrating two or more nodes (400) in a distributed wireless network to a centralized wireless network, the method (500) comprising the steps of: transmitting (S501), by a first bridge device (200) in the centralized wireless network, one or more parameters related to the centralized wireless network to a second bridge device (300) in the distributed wireless network; collecting (S502) topology information between two or more nodes (400) by querying the two or more nodes (400) in the distributed wireless network; determining (S503) a sequential list for requesting two or more nodes (400) to join the centralized wireless network based on the topology information; the two or more nodes (400) are requested (S504) to join the centralized wireless network according to the sequential list.

Description

Technical Field

[0001] The present invention relates to the field of wireless communications. More particularly, various methods, devices and systems related to migrating a node between two different wireless networks are disclosed herein. Background Art

[0002] Zigbee, Thread, and Bluetooth Mesh are examples of wireless networks for IoT applications such as lighting and building automation. They provide low-latency, low-rate services that enable messages to be passed between, for example, a light switch and one or more luminaires. Mesh networks provide great flexibility and scalability for the system. However, on the other hand, centralized Zigbee networks provide improved security and control over the network, which is also attractive in many applications. Therefore, there is a need to migrate existing distributed networks to centralized networks in a reliable manner.

[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 well-defined way to move an existing distributed network to a centralized network without having to redeploy the entire network. Furthermore, it may also be desirable to be able to make the transition on-the-fly with reduced impact on network functionality.

[0004] US2021185485A1 relates to a system for selecting one or more devices for presence and / or location detection in a wireless network, and the system includes a processor configured to determine the suitability of each of a plurality of devices for transmitting, receiving and / or processing radio frequency signals for presence and / or location detection while leaving sufficient resources for network communications.

[0005] EP2661127B1 relates to a control device of an autonomous routing area network, which includes a processing unit configured to perform actions including the following: receiving a request to join the autonomous routing area network from a requesting device; and in response to receiving the request: determining whether the requesting device is an isolated device based on information included in the request, wherein if the requesting device is unable to join a network other than the autonomous routing area network, the requesting device is an isolated device; based on whether the requesting device is an isolated device, controlling the rejection or acceptance of the requesting device's entry into the autonomous routing area network. Summary of the invention

[0006] 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 that may arise during the transition from a distributed network to a centralized network is that if those router nodes or parent nodes leave the distributed network earlier than the end nodes and / or leaf nodes, those end nodes and / or leaf nodes may lose connection to the distributed network without being notified of the transition and then become unreachable.

[0007] The inventors have recognized that it would be beneficial to regulate the network migration process by taking into account topology information. More particularly, the object of the invention is achieved by a method as claimed in claim 1 and a bridge device as claimed in claim 12 .

[0008] According to a first aspect of the present invention, a method for migrating two or more nodes in a distributed wireless network to a centralized wireless network is provided. The method comprises the following steps: a first bridge device in the centralized wireless network sends one or more parameters related to the centralized wireless network to a second bridge device in the distributed wireless network; topology information between two or more nodes is collected by querying two or more nodes in the distributed wireless network; based on the topology information, a sequence list is determined for requesting two or more nodes to join the centralized wireless network; two or more nodes are requested to join the centralized wireless network according to the sequence list; wherein the sequence list is arranged to allow a first node among the two or more nodes to join the centralized wireless network earlier than a second node among the two or more nodes when the first node receives a message from the second bridge device via a relay of a second node in the distributed wireless network.

[0009] The one or more parameters may be related to a network ID of the centralized network, an operating channel of the centralized network, or another network parameter related to the centralized network.

[0010] Topology information may be gathered by obtaining neighbor information associated with each individual node, such as a list of neighbors with which it has a one-hop direct link, output power used to establish a link with a neighbor node, received power from a neighbor node, or link quality information associated with a link with another node.

[0011] Thus, topology information may be related to the physical deployment of nodes in the system. Topology information may also be related to the network structure of the 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.

[0012] The sequence list is used to sort nodes for reliable migration from the distributed network to the centralized network, thereby avoiding the node being unreachable in the distributed network due to a router node or a parent node connected to the distributed network leaving the distributed network prematurely.

[0013] Advantageously, the method further comprises the step of providing, by the second bridge device, information relating to the two or more nodes to the first bridge device.

[0014] The second bridge device may provide the first bridge device with information related to the individual nodes to further assist the first bridge device in setting up the centralized network.

[0015] Alternatively, the first bridge device may join the distributed network before it opens a new centralized network. And then, the first bridge device may collect such information itself.

[0016] However, since the second bridge device may have already collected such information during its normal data communications in the distributed network, it may be more efficient for the second bridge device to provide such information directly to the first bridge device.

[0017] Advantageously, the method further comprises the step of providing, by the second bridge device, the sequence list to the first bridge device.

[0018] The second bridge device may request the node to join the centralized network according to the sequential list. And in parallel, the second bridge device may also inform the first bridge device of the list. And then accordingly, the first bridge device will also follow the list to allow the node to join the centralized network sequentially.

[0019] Alternatively, when the second bridge device determines the sequence list, it can also simply provide the sequence list to the first bridge device, allowing the first bridge device to request the node to join the centralized network. This can be achieved if the first bridge device can stay in the distributed network and the centralized network at the same time. And then the first bridge device can send requests to the nodes sequentially in the distributed network according to the list, and at the same time allow the nodes to join the centralized network. Another option is that when obtaining the sequence list, the first bridge device can first stay in the distributed network to send requests to the nodes sequentially and specify in the request a delay period for each node to join the new centralized network. And then the new bridge device can leave the distributed network and open the centralized network to allow nodes to join.

[0020] In one example, the method further includes the step of opening, by the first bridge device, the centralized wireless network for the node to join.

[0021] As described above, the step of opening the centralized wireless network by the first bridge device may be performed before the switching process, such that the first bridge device opens the centralized wireless network and then notifies the second bridge device about one or more configuration parameters of the new centralized wireless network.

[0022] Alternatively, the step of opening the centralized wireless network by the first bridge device may be performed during the transition process, such that the first bridge device determines one or more configuration parameters of the new centralized wireless network to be created and notifies the second bridge device of such parameters. The actual step of opening the centralized wireless network may be performed during or after two or more nodes are requested to join the centralized network.

[0023] Preferably, the method further comprises the step of transmitting, by the second bridge device, one or more parameters related to the centralized wireless network to the two or more nodes.

[0024] This step may also be combined with the step of requesting two or more nodes to join the centralized wireless network.

[0025] Alternatively, the first bridge device may be selected to join the distributed network and directly transmit one or more parameters related to the centralized wireless network to the two or more nodes.

[0026] Advantageously, the information associated with the two or more nodes includes at least one of addresses, configuration parameters and status information associated with the two or more nodes.

[0027] Advantageously, the method further comprises the step of restoring a node among the two or more nodes in the centralized wireless network to a previous state of the node in the distributed wireless network.

[0028] By knowing the configuration, settings, state or scenario of individual nodes in a distributed network, the first bridge device or the new bridge device can restore the node to the previous configuration, settings, state or scenario after the node moves to a new centralized network, which further enhances the smooth transition.

[0029] In a preferred embodiment, the method further comprises the steps of: generating a link key for one of the two or more nodes in the centralized wireless network based on the information obtained from the second bridge device; and notifying the node of the link key.

[0030] Upon receiving information related to an individual node, such as an identifier or address of the node, the first bridge device may generate an end-to-end link key for the individual node. The end-to-end link key may be used to improve the security of end-to-end communications in a centralized network.

[0031] This step may be performed by a first bridge device of the centralized network, such that the first bridge device informs the various nodes of their dedicated link keys.

[0032] Note that it is also possible to select a first bridge device to join the distributed network and collect information related to two or more nodes by the first bridge device itself.

[0033] In one example, when the first node receives a message from the second bridge device via a relay of the second node in the distributed wireless network, the sequence list is arranged to allow a first node among the two or more nodes to join the centralized wireless network earlier than a second node among the two or more nodes.

[0034] The order list is arranged to avoid a situation where a critical node (e.g., a node that is the only link between two sub-parts of the network) moves to the new centralized network earlier than other nodes, which would render some nodes in the distributed network unreachable and thus unable to be notified of the switch. For example, a router node or parent node would leave the distributed network later than an end node or child node that depends on it to access the distributed network.

[0035] Advantageously, at least one of the distributed wireless network and the centralized wireless network is in accordance with the Zigbee standard.

[0036] The Zigbee standard is widely used in home automation and lighting control applications. The Zigbee network layer itself supports both star and tree networks as well as general mesh networking. Powerful topology control provides great flexibility in control systems, especially for reaching destination nodes far away from the source node using direct links.

[0037] ZigBee specifies three different device types: ZigBee Coordinator (ZC), ZigBee Router (ZR), and ZigBee End Device (ZED). These three devices play different roles in a ZigBee network. Zigbee Routers (ZR) pass data between devices and / or coordinators. Zigbee End Devices (ZED) provide only basic functionality. ZEDs are leaf nodes. They communicate only through their parent node, and unlike router devices, they cannot relay messages to other nodes. They do not participate in any routing. End devices rely on their parent routers to send and receive messages. With respect to IEEE 802.15.4, ZCs and ZRs are full function devices (FFDs), while ZEDs are reduced function devices (RFDs).

[0038] Thus, topology information between two or more nodes in a distributed wireless network may be determined jointly by the physical locations of the nodes, the functionality supported by the nodes, and the types of roles they play in the distributed network.

[0039] Advantageously, the first bridge device and the second bridge device are physically co-located.

[0040] The first bridge device and the second bridge device may be deployed adjacent to each other, such as within direct wireless communication range. It may also be the case that the first bridge device and the second bridge device are co-located such that the first bridge device will be replaced by the second bridge device after the migration. Physically, it may also be possible that the first bridge device and the second bridge device are the same bridge device. It also applies to the case where an existing bridge device has the ability to convert to a centralized network through a firmware update. All of these steps will simply be performed on the same bridge device to move its network from a distributed topology to a centralized topology.

[0041] Preferably, the first bridge device and the second bridge device have an additional communication channel connected to each other which does not belong to the distributed wireless network or the centralized wireless network.

[0042] The additional communication channel may be 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 (e.g., Ethernet). The first bridge device and the second bridge device may also be connected via a Wi-Fi network, a BLE link, or a 4G / 5G cellular link.

[0043] According to a second aspect of the present invention, a bridge device is provided. A bridge device for use in a distributed wireless network, comprising: a communication interface configured to receive one or more parameters related to a centralized wireless network from another bridge device; a radio device configured to collect topology information between two or more nodes by querying two or more nodes on the distributed wireless network; and a controller configured to determine a sequence list for requesting two or more nodes to join the centralized wireless network based on the topology information; wherein the radio device is further configured to request the two or more nodes to join the centralized wireless network according to the sequence list; wherein the sequence list is arranged to allow a first node among the two or more nodes to join the centralized wireless network earlier than a second node among the two or more nodes when the first node receives a message from the bridge device via a relay of a second node in the distributed wireless network.

[0044] The entire process of migrating nodes to a centralized network can be initiated by a new bridge device in the centralized network, which first sends one or more parameters related to the centralized wireless network to an existing bridge device in the distributed network. One or more parameters may include a network identifier (ID) of the centralized network, an operating channel of the centralized network, or another network parameter related to the centralized network. And then, the bridge device or the existing bridge device in the distributed wireless network can be responsible for the main responsibility in arranging a smooth transition. Topology information is used to determine a sequence list to ensure that no node is unreachable in the distributed network during the transition. Topology information can be collected by an existing bridge device by querying nodes triggered by the migration process. It may also be the case that during earlier data communications in the distributed network, the existing bridge device regularly collects topology information. Based on the topology information, the existing bridge device determines a sequence list and requests the node to join the centralized network according to the sequence list.

[0045] Advantageously, when the first node receives a message from the bridge device via relaying of a second node in the distributed wireless network, the sequence list is arranged to allow a first node among the two or more nodes to join the centralized wireless network earlier than a second node among the two or more nodes.

[0046] Advantageously, the communication interface of the bridge device is further configured to send information relating to the two or more nodes to another bridge device.

[0047] Existing bridge devices can also provide additional information related to individual nodes, such as their addresses, configuration parameters, or the state of the node in the distributed network. This information can help the new bridge device restore the node to a previous state or configuration after the node is moved to a new centralized network. This information can also be used to generate dedicated link keys to protect the end-to-end communication link. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In the drawings, similar reference numerals are used throughout the different Figure 1 Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention.

[0049] Figure 1 A possible system setup is shown;

[0050] Figure 2 A flow chart illustrating a method for migrating two or more nodes in a distributed wireless network to a centralized wireless network;

[0051] Figure 3 A block diagram showing a bridge device for use in a distributed wireless network; and

[0052] Figure 4 An example of a bridge device is illustrated. DETAILED DESCRIPTION

[0053] The embodiments set forth below represent information that enables those skilled in the art to practice these embodiments. When reading the following description in accordance with the accompanying drawings, those skilled in the art will understand the concepts of the present disclosure and will recognize the applications of these concepts that are not particularly proposed herein. It should be understood that these concepts and applications fall within the scope of the present disclosure.

[0054] For wireless communications, a distributed network topology offers improved flexibility and scalability. However, it can also bring the risk of compromised security. Taking Zigbee as an example, there are well-known weaknesses in distributed Zigbee networks, especially during the joining process. In order 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 move or 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 disruption to the network. Preferably, the transition can be accomplished instantly.

[0055] One way is to use the Zigbee Join Cluster (ZCC), which essentially defines messages that can be sent to individual nodes in the network, with information such as the Zigbee PAN-ID of the centralized network to join, the extended PAN ID, the network and link keys, etc. It also defines messages that instruct the node to restart and join the new network. Upon restart, the node joins the new network using the more secure centralized join mechanism defined in Zigbee, and also "realizes" that it is now part of a centralized network.

[0056] Another way is to define custom messages that essentially perform a subset of the functionality of ZCC. In its simplest form, a simple restart and rejoin message can be sent to a node, which will cause the node to search for a new network, and then find the centralized network and join it.

[0057] Regardless of which method is used, nodes need to be pushed to leave the existing distributed network to join the new centralized network. Known methods show how to move a single node from a distributed network to a centralized network. However, there is still a lack of a process / method for reliably migrating every node in a distributed network to a centralized network. As an example, a problem that may arise is that if a key node (e.g., a node that is the only link between two sub-parts of the network) moves to the new centralized network earlier than other nodes, this will make some nodes in the distributed network unreachable and unable to be notified about the transition. One solution is that the extended PAN-ID, PAN-ID, network key, etc. can remain the same for both the existing distributed network and the new centralized network. However, this solution may bring some unexpected confusion to the nodes.

[0058] The present invention solves this problem in a more generalized way, where the centralized network can be completely independent, with refreshed network parameters, such as PAN-ID, network keys, etc. This also provides improved security, since the new centralized network is free to choose the refreshed new keys, and thus the new centralized network starts up as if it had been built from scratch.

[0059] Figure 1 A possible system setup is shown, where the existing bridge device 300 and the new bridge device 200 are positioned in close proximity or even co-located. According to the Zigbee protocol, the traditional mechanism for migrating nodes from an existing distributed network to a new centralized network is to transfer 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 can be encrypted and transmitted via a wired connection (such as via an IP network) or over a wireless connection between the existing bridge device 300 and the new bridge device 200. The wireless connection can be based on another wireless communication protocol different from the existing distributed network or the new centralized network, such as Wi-Fi, BLE or 4G / 5G cellular.

[0060] Figure 1 It also highlights that problems may arise if the existing bridge device 300 would naively instruct the nodes (A to E) to switch sequentially to join the new bridge device 200 in centralized mode (by issuing a Zigbee Join Initialization Cluster command or a simpler custom command). Once node C leaves the distributed network, nodes D and E will no longer be reachable.

[0061] Therefore, a new solution is needed to solve this problem. As an example of implementing the proposed solution, the steps involved may be as follows:

[0062] a) The new bridge device 200 starts up in centralized mode and selects network parameters such as PAN-ID, extended PAN-ID, operating channel, etc. It also randomly selects a network key for the new centralized network. It may also immediately open its network for centralized joining.

[0063] b) The new bridge device 200 transmits the PAN-ID, extended PAN-ID, operating channel to the existing bridge device 300, with a request to transfer the node or device to it. The new bridge 200 may not transmit its network key to the existing bridge device 300, as this is unnecessary and undesirable from a security perspective.

[0064] c) The existing bridge device 300 may be triggered by a request from the new bridge device 200 to ping different nodes to obtain topology information. It is also possible that the existing bridge device 300 periodically (such as during regular communications for the distributed network) pings different nodes to obtain topology information. The topology information may include neighbor information of a node, such as its direct communication link / neighbors, the transmit power used to establish a link to a neighbor node, the signal strength received from the neighbor node, etc. Based on the topology information obtained in this step, the existing bridge has an overview of the network topology.

[0065] d) Based on the topology information collected in the previous step, the existing bridge device 300 determines a sequence list for requesting two or more nodes to join the centralized wireless network based on the topology information, and then starts to request the nodes to join the centralized network according to the sequence list. Figure 1 In the network illustrated in , the existing bridge device 300 may first ask nodes D and E to join the new bridge 200, followed by node C, and then followed by nodes A and B. This order will ensure that all nodes in the network receive the message to move to the centralized network.

[0066] e) To send these messages to the nodes, the existing bridge device 300 may use ZCC commands, which convey the PAN-ID, extended PAN-ID, operating channel, etc. of the new centralized network for the node to join. For nodes from different manufacturers that may not implement ZCC commands, the existing bridge device 300 may also issue a customized simple command (e.g., a leave request) to request the node to leave the existing distributed network and then look for a new centralized network to join.

[0067] f) The existing bridge device 300 keeps a list of identifiers or addresses (e.g., IEEE addresses) of the nodes that it has requested to join the centralized network, and passes this list to the new bridge device 200 along with other information such as the current settings and status of the nodes (e.g., for a lighting fixture, it can be on / off; color temperature status).

[0068] g) The new bridge 200 uses the information obtained in the previous step to successfully join the nodes in centralized mode. For example, the list obtained in the previous step can help it obtain additional information derived from the installation code (possibly from the backend server) to obtain the link keys that enable these nodes to successfully join the centralized network.

[0069] h) Once all required nodes have joined the new centralized network, the new bridge device 200 uses the information obtained in step f) to return the nodes to the settings or states (on / off, color, etc.) they were previously in.

[0070] The topology information may include its links / neighbors, transmit / receive power, etc. Based on the topology information, an existing bridge device or a new bridge device may derive an overview of the network topology between multiple nodes.

[0071] Figure 2 A flow chart of a method 500 for migrating two or more nodes in a distributed wireless network to a centralized wireless network is shown. The method 500 comprises the following steps: in step S501, a first bridge device 200 in the centralized wireless network sends one or more parameters related to the centralized wireless network to a second bridge device 300 in the distributed wireless network; in step S502, topology information between two or more nodes 400 is collected by querying two or more nodes 400 in the distributed wireless network; in step S503, a sequence list for requesting two or more nodes 400 to join the centralized wireless network is determined based on the topology information; and in step S504, two or more nodes 400 are requested to join the centralized wireless network according to the sequence list.

[0072] Figure 3A block diagram of a bridge device 300 for use in a distributed wireless network is shown. As a basic setup, the bridge device 300 includes a communication interface 310, a radio device 320, and a controller 330. The communication interface 310 is configured to receive one or more parameters related to a centralized wireless network from another bridge device 200. The radio device 320 is configured to collect topology information between two or more nodes 400 by querying two or more nodes 400 on the distributed wireless network. The controller 330 is configured to determine a sequential list for requesting two or more nodes 400 to join the centralized wireless network based on the topology information. The radio device 320 is also configured to request two or more nodes 400 to join the centralized wireless network according to the sequential list.

[0073] As an example, Figure 4 As shown in , the present invention can be implemented by a network transmission module in a bridge device. The network transmission module can be implemented in a controller of the bridge device. In the existing bridge device, in the above-mentioned step b), the network transmission module obtains parameters related to the new centralized network from the new bridge device 200, as well as a request to transfer nodes or devices from the existing distributed network to the new centralized network. Therefore, the network transmission module can control the radio device to perform step c), such as querying the node for topology information. It is also possible that the network transmission module obtains topology information from the internal database of the bridge, which is previously collected during regular communication with the node. Based on the collected topology information, the network transmission module performs calculations in step d) to generate an appropriate sequence list for migrating the node to the new bridge device. Then, the network transmission module continues to monitor the transmission by querying via the radio device of the bridge device and optionally by receiving additional status responses from the new bridge device.

[0074] In the new bridge device, the network transmission module may be responsible for starting the new centralized network as in step a), and controlling the communication interface to transmit parameters related to the new centralized network to the existing bridge device in step b). After the existing bridge device has provided the sequence list and the information related to the two or more nodes, the network control module of the new bridge device controls its radio device to allow the node to join according to the sequence list, and utilizes the information related to the two or more nodes to restore the node to the previous setting, state or scene in the distributed network. Additionally, it may control the communication interface to notify the existing bridge device about the status of the transmission.

[0075] Note that the present invention is equally applicable to situations where an existing bridge device has the capability to convert to a centralized network through a firmware update. All of these steps will simply be performed on the same bridge device to move its network from a distributed topology to a centralized topology.

[0076] The method according to the present invention can be implemented on a computer as a computer-implemented method, or in dedicated hardware, or in a combination of both.

Claims

1. A method (500) for migrating two or more nodes (400) in a distributed wireless network to a centralized wireless network, the method (500) comprising the following steps: - A first bridge device (200) in a centralized wireless network sends (S501) one or more parameters related to the centralized wireless network to a second bridge device (300) in a distributed wireless network; - collecting (S502) topology information between two or more nodes (400) in a distributed wireless network by querying the two or more nodes (400); - determining (S503) a sequential list for requesting two or more nodes (400) to join the centralized wireless network based on the topology information; - requesting (S504) two or more nodes (400) to join the centralized wireless network according to the sequence list; The sequence list is arranged to allow a first node among two or more nodes (400) to join the centralized wireless network earlier than a second node among the two or more nodes (400) when the first node receives a message from a second bridge device (300) via a relay of a second node in the distributed wireless network.

2. The method (500) according to claim 1, further comprising: - Information related to two or more nodes (400) is provided by the second bridge device (300) to the first bridge device (200).

3. The method (500) according to claim 1 or 2, further comprising: - providing the sequence list by the second bridge device (300) to the first bridge device (200).

4. The method (500) according to any one of the preceding claims, further comprising: - The first bridge device (200) opens the centralized wireless network for the node (400) to join.

5. The method (500) according to any one of the preceding claims, further comprising: - transmitting one or more parameters related to the centralized wireless network to two or more nodes (400) by the second bridge device (300).

6. The method (500) of any one of the preceding claims 2-5, wherein the information associated with the two or more nodes (400) comprises at least one of addresses, configuration parameters and status information associated with the two or more nodes (400).

7. The method (500) according to any one of the preceding claims 2-6, further comprising: - Restoring a node among two or more nodes (400) in a centralized wireless network to a previous state of the node in a distributed wireless network.

8. The method (500) according to any one of the preceding claims 2-7, further comprising: - generating a link key for one of two or more nodes (400) in the centralized wireless network based on the information obtained from the second bridge device (300); and - Notify nodes of link keys.

9. The method (500) according to any of the preceding claims, wherein at least one of the distributed wireless network and the centralized wireless network is according to the Zigbee standard.

10. The method (500) according to any one of the preceding claims, wherein the first bridge device (200) and the second bridge device (300) are physically co-located.

11. The method (500) according to any one of the preceding claims, wherein the first bridge device (200) and the second bridge device (300) have a further communication channel connecting one another which does not belong to the distributed wireless network or the centralized wireless network.

12. A bridge device (300) for use in a distributed wireless network, comprising: - a communication interface (310) configured to receive one or more parameters related to the centralized wireless network from another bridge device (200); - a radio device (320) configured to collect topology information between two or more nodes (400) on a distributed wireless network by querying the two or more nodes (400); and - a controller (330) configured to determine, based on the topology information, a sequential list for requesting two or more nodes (400) to join the centralized wireless network; wherein the radio device (320) is further configured to request two or more nodes (400) to join the centralized wireless network according to the sequential list; The sequence list is arranged to allow a first node among two or more nodes (400) to join the centralized wireless network earlier than a second node among the two or more nodes (400) when the first node receives a message from a bridge device (300) via a relay of a second node in a distributed wireless network.

13. The bridge device (300) of claim 12, wherein the communication interface is further configured to send information related to the two or more nodes (400) to another bridge device (200).

Images