Load balancing system for software-defined wireless sensor networks and method thereof

Abstract

The present application is a load balancing system and method for software-defined wireless sensor networks. The first controller detects the load of the transmission paths between the gateway and the nodes. When the ratio of the overloaded transmission paths exceeds a threshold, the first controller sends an overload warning message to the second controller. After receiving the overload warning message, the second controller adds the first controller to an observation list and stops transferring new gateways to the first controller for management. The present application can effectively balance the load of the controllers and avoid the problem of controller overload caused by a sudden large number of path changes due to node failure, thereby improving the stability and reliability of the network.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and more particularly to a load balancing method and system for software-defined wireless sensor networks. Background Technology

[0002] With the increasing prevalence of wireless sensor network applications, application scenarios involving high data traffic fluctuations and the coexistence of multiple data types are also gradually increasing. However, traditional sensor network routing methods require the participation of sensor nodes, which affects the lifespan of sensor nodes, which already have limited energy.

[0003] To effectively manage transmission paths in wireless sensor networks and thus extend sensor node lifespan, Software-Defined Networking (SDN) technology has been increasingly applied to wireless sensor networks. While SDN algorithms can balance traffic within the network and improve sensor node lifespan, current algorithms cannot handle the sudden surge in path changes caused by sensor node failures, which can overload the SDN controller.

[0004] Therefore, there is a need for a load balancing method and system for software-defined wireless sensor networks (SDNs) that can effectively balance the load of SDN controllers, avoid overloading of a single SDN controller, and improve the stability and reliability of SDNs. Summary of the Invention

[0005] The main objective of this invention is to provide a load balancing system and method for software-defined wireless sensor networks, which can effectively balance the load of the controller and avoid the problem of sudden overload of the controller caused by sudden large-scale path changes due to node failure, thereby improving the stability and reliability of the network.

[0006] This invention provides a load balancing system for a software-defined wireless sensor network, including a gateway, a first controller, and a second controller. The gateway connects to multiple nodes, and the gateway and the multiple nodes have multiple transmission paths. The first controller manages the gateway and detects the load of the multiple transmission paths. When the ratio of overloaded multiple transmission paths exceeds a ratio threshold, an overload warning message is issued. The second controller connects to the first controller and receives the overload warning message. It then adds the first controller that issued the overload warning message to a watchlist and stops transferring new gateways to the first controller in the watchlist.

[0007] The second controller is characterized in that it also receives load information from the first controller. When the load information of the first controller exceeds a load threshold, the second controller is added to the high-load list. When the load information of the first controller is below the load threshold, the second controller is added to the low-load list.

[0008] The feature is that the second controller selects the gateway with the highest load managed by the first controller in the high-load list; estimates the connection quality assessment value of the gateway with the highest load to each first controller in the low-load list; and transfers the gateway with the highest load to the first controller with the highest connection quality assessment value for management.

[0009] The feature is that the second controller also uses an evaluation value equation to estimate the online quality evaluation value, as shown below: , This is the online quality assessment value. and As weight, This is the maximum load value for the first controller. This refers to the load value of one of the first controllers in the low-load list. The number of relay points for the highest-load gateway to connect to one of the low-load lists of the first controller.

[0010] The feature is that the first controller further adjusts the reporting frequency of the load information sent to the second controller, and the reporting frequency is adjusted according to the reporting frequency equation, which is shown below: , For the frequency of return, For a point in time, This can be expressed as the following equation: , The packet size output by the first controller. The packet size input to the first controller. This represents the total number of packets input and output by the first controller.

[0011] This invention also provides a load balancing method for a software-defined wireless sensor network, comprising the following steps: A first controller detects the load on multiple transmission paths between a gateway and multiple nodes. When the ratio of overloaded multiple transmission paths exceeds a ratio threshold, the first controller issues an overload warning message. Upon receiving the overload warning message, a second controller adds the first controller to a watchlist and stops transferring new gateways to the first controller in the watchlist for management. Attached Figure Description

[0012] Figure 1 This is an architecture diagram of the load balancing system according to an embodiment of the present invention.

[0013] Figure 2 This is a flowchart illustrating the steps of a load balancing method according to an embodiment of the present invention.

[0014] Figure 3 This is a flowchart illustrating the steps of migrating the load of a high-load controller according to an embodiment of the present invention.

[0015] Explanation of main component symbols Load balancing system 1 Control Domain 10 Control domain 10' Node 12 Node 12' Gateway 14 Gateway 14' First controller 16 First controller 16' Second controller 20 Steps S10~S14 Steps S20~S24.

[0016] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0017] To facilitate understanding and implementation of the present invention by those skilled in the art, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0018] This invention relates to a load balancing system and method for software-defined wireless sensor networks. It avoids the problem of controller overload caused by sudden and large-scale path changes due to sensor node failure in software-defined networking (SDN) architecture, which would require the controller with a high load to bear an additional large amount of path adjustment work.

[0019] The SDN architecture comprises an infrastructure layer, a control layer, and an application layer. The infrastructure layer includes gateways for edge devices and sensor nodes or routing nodes for terminal devices. Gateways act as a bridge between the upper control layer and the lower terminal devices. Gateways can communicate with lower-level terminal devices wirelessly, and simultaneously transmit data with the upper control layer cloud devices using traditional wired communication methods.

[0020] The control layer defines the controller for the cloud-based device network. The controller senses the state of all nodes in the network to make corresponding decisions and control the network's operation. The controller is implemented using cloud resources, and network management and security management mechanisms are deployed within the control layer.

[0021] The application layer is based on cloud-based data servers and uses corresponding applications to meet the needs of different application scenarios.

[0022] Please refer to Figure 1 This illustrates the system architecture of this embodiment. The system in this embodiment primarily applies the control layer and infrastructure layer of the SDN architecture to the management of wireless sensing nodes. For example... Figure 1 As shown, the load balancing system 1 includes multiple nodes 12, 12', a gateway 14, 14', a first controller 16, 16', and a second controller 20, all connected in sequence via communication. It should be noted that... Figure 1 This is merely an example and should not be construed as a limitation of the invention. For example, the number of gateways 14 connected to the first controller 16 may also be multiple; more first controllers 16, 16' may also be deployed.

[0023] The aforementioned nodes 12, 12' and gateways 14, 14' are categorized as the infrastructure layer in the SDN architecture. The first controllers 16, 16' and the second controller 20 are categorized as the control layer in the SDN architecture. The second controller 20 can communicate with the application layer via wired or wireless means. Figure 1 The data server (not shown in the text) Figure 1 (Not shown in the image).

[0024] In this embodiment, the multiple nodes 12 and 12' include sensor nodes and router nodes. Taking the Industrial Internet of Things (IIoT) as an example, when the multiple nodes 12 and 12' are sensor nodes, they can be installed on robotic arms, conveyor belts, products, etc., to monitor the robotic arms, conveyor belts, products, etc., and generate sensing data. The sensor nodes can directly transmit the sensing data to the gateways 14 and 14'. The sensor nodes can also transmit the sensing data to nearby router nodes, and then transmit it to the gateways 14 and 14' through the router nodes. In this embodiment, the router nodes are used to relay data transmission between the multiple sensor nodes and the gateways 14 and 14', and at the same time receive routing rules from the first controllers 16 and 16' to ensure that data traffic follows the optimal path. The router nodes are also used to monitor the status of themselves and neighboring nodes, such as path load, and report to the first controllers 16 and 16' to receive routing configuration instructions.

[0025] Gateways 14 and 14' can be devices such as modems, hubs, bridges, or switches. Gateways 14 and 14' communicatively connect multiple nodes 12 and 12' with the first controllers 16 and 16', enabling the integration of heterogeneous wireless sensor networks with SDN network architectures. In this embodiment, gateways 14 and 14' are used to forward data packets to designated paths according to flow table rules issued by the first controllers 16 and 16', and simultaneously receive instructions from the first controllers 16 and 16' to reconfigure data flow paths, thereby reducing the pressure on high-load nodes.

[0026] In this embodiment, to adapt to application scenarios with a large number of nodes or a wide distribution range, a multi-controller architecture is adopted, namely, first controllers 16 and 16'. First controllers 16 and 16' can be deployed in locations geographically close to the multiple nodes 12 and 12' to reduce communication latency between the multiple nodes 12 and 12' and the first controllers 16 and 16'. First controllers 16 and 16' are responsible for managing the multiple nodes 12 and 12' and gateways 14 and 14', respectively, forming control domains 10 and 10'.

[0027] The first controllers 16 and 16' manage the network topology and routing tables within their control domains 10 and 10', calculate the optimal route based on network information, and distribute the flow tables to gateways 14 and 14'. Simultaneously, the first controllers 16 and 16' also dynamically adjust routes based on the real-time status of multiple nodes 12 and 12' to avoid overloading a single node.

[0028] The second controller 20 is used to coordinate the first controllers 16 and 16' to achieve dynamic load balancing. For example, when the load on the first controller 16 is too high, the gateway 14 can be dynamically migrated to the first controller 16' with a lower load.

[0029] To improve system stability and reliability, it is necessary to avoid situations where a single controller may experience momentary overload. For example, taking control domain 10 as an example, when one of the multiple nodes 12 fails, neighboring nodes may frequently report abnormal states to the gateway 14 and the first controller 16, such as link interruptions or data transmission failures, increasing the communication load on the first controller 16. Simultaneously, the first controller 16 also needs to send updated flow table rules to the gateway 14 or router nodes, further increasing its communication demands. Especially in scenarios where multiple nodes 12 form a large-scale wireless sensor network, frequent node failures may also increase the frequency of topology updates, causing momentary overload of the first controller 16.

[0030] To achieve dynamic load balancing between the first controllers 16 and 16', please refer to... Figure 2The diagram shows a flowchart of the load balancing method executed by the first controllers 16 and 16'. The explanation of the steps in the flowchart uses the first controller 16 as an example only; the same applies to the first controller 16', and will not be repeated here.

[0031] As shown in step S10, the first controller 16 estimates the load of multiple transmission paths between the gateway 14 and multiple nodes 12.

[0032] For example, the first controller 16 can estimate the load of multiple transmission paths based on the topology of the control domain 10 it maintains, combined with the traffic statistics of the gateway 14 and multiple nodes 12.

[0033] In one example, the load of each transmission path can be calculated using the following formula: Transmission path load Node load is the amount of data processed by nodes on the transmission path or the remaining energy of the nodes; link load is the data rate of communication between nodes or the remaining energy.

[0034] Next, proceeding to step S12, when the first controller 16 detects that the percentage of overloaded transmission paths exceeds a certain threshold, the first controller 16 sends an overload warning message to the second controller 20. For example, an overload situation might occur when the bandwidth utilization of a transmission path is 90%, which is considered an overload condition. The percentage threshold is, for example, 75%. When the percentage of overloaded transmission paths reaches 76% of the total number of transmission paths, it indicates that the percentage threshold has been exceeded, and the first controller 16 sends an overload warning message to the second controller 20. This overload warning message may contain the identification information of the first controller 16, providing the second controller 20 with confirmation that the overload warning message was issued by the first controller 16.

[0035] Next, proceed to step S14. After receiving the overload warning message, the second controller 20 confirms the first controller 16 that issued the overload warning message based on the identity information and adds the first controller 16 that issued the overload warning message to the watch list. If load balancing is started in the future, the transfer of the new gateway 14 to the first controller 16 in the watch list can be stopped.

[0036] The above method prevents the second controller 20 from transferring new gateways to the first controller 16 in the watchlist during system load balancing, thus avoiding a momentary overload of the first controller 16. For example, if it is necessary to migrate gateway 14' managed by the first controller 16', the second controller 20 will not migrate gateway 14' to the first controller 16', avoiding the first controller 16 from issuing additional updated flow table rules to gateway 14' or router nodes, which would increase workload and cause the first controller 16 to overload.

[0037] In addition to the aforementioned observation list, the second controller 20 also includes a high-load list and a low-load list. The second controller 20 can classify the first controllers 16 and 16' into the high-load list and low-load list based on their load status. During subsequent load balancing, the second controller 20 can quickly select the first controllers 16 and 16' from the low-load list that can have their load increased. The classification method is explained below.

[0038] In this embodiment, there are multiple control domains 10 and 10'. Each control domain 10 and 10' has a first controller 16 and 16' that periodically sends load information to the second controller 20. The load information includes the processor utilization rate of the first controllers 16 and 16', the total number of packets processed by the first controllers 16 and 16', and their identification information. Upon receiving the load information, the second controller 20 can determine which first controller 16 or 16' the load information belongs to, based on the identification information, or it can determine the load status of the first controllers 16 and 16' based on the processor utilization rate and the total number of packets processed.

[0039] In this embodiment, the first controllers 16 and 16' can also adjust the reporting frequency of load information to the second controller 20. In one example, the reporting frequency will increase as the load of the first controllers 16 and 16' increases.

[0040] In one example, the report frequency can be adjusted primarily based on the packet volume processed by the first controllers 16 and 16'. The report frequency can be adjusted according to the report frequency equation, which is shown below: For the frequency of return, For a point in time, This can be expressed as the following equation: , The packet size output by the first controller 16, 16' The packet quantity input to the first controller 16, 16' The total number of packets input and output to the first controllers 16 and 16'.

[0041] After receiving load messages, the second controller 20 can classify the first controllers 16 and 16' of multiple network control domains 10 and 10' according to the load messages. The second controller 20 can receive load messages from the first controllers 16 and 16' within the same time period, such as one second. The second controller 20 determines whether the load message of the first controller 16 exceeds the load threshold and adds the first controller 16 to the high load list. When the load message of the first controller 16' is below the load threshold, the second controller 20 adds the first controller 16' to the low load list. For example, the load threshold includes a processor utilization threshold and a total packet processing threshold. For instance, the processor utilization threshold is set to 90%, and the total packet processing threshold is set to 8333 packets / second. When both the processor utilization and the total packet processing of the load message are greater than the processor utilization threshold and the total packet processing threshold, or greater than one of them, it is defined as exceeding the load threshold. When both the processor utilization and the total packet processing of the load message are lower than the processor utilization threshold and the total packet processing threshold, it is defined as being below the load threshold.

[0042] After classifying the first controllers 16 and 16' of multiple control domains 10 and 10', the second controller 20 can quickly determine which first controllers 16 and 16' are under high load and which are under low load. This classification is beneficial for the second controller 20 to allocate the load of the first controllers 16 and 16' when performing load balancing adjustments.

[0043] Please refer to Figure 1 and Figure 3 This illustrates the load balancing method performed by the second controller 20. In this embodiment, the first controller 16 of control domain 10 is classified in the high-load list and is the first controller 16 with the highest load. The first controller 16' of control domain 10' is classified in the low-load list. In this embodiment, there can be multiple first controllers 16 in the high-load list. There can also be multiple first controllers 16' in the low-load list.

[0044] In step S20, the second controller 20 selects multiple first controllers 16 from the high-load list. Then, from each of the aforementioned first controllers 16, the second controller 20 selects the gateway 14 managed by the first controller 16 that has the highest load. The gateway with the highest load can be determined based on the packet processing volume and the processing capacity of the gateway 14's processor. The higher the packet processing volume and the processor's processing capacity, the higher the load.

[0045] Next, in step S22, the second controller 20 estimates the connection quality assessment value for each of the highest-load gateways 14 managed by each first controller 16 connecting to each of the ten first controllers 16' in the low-load list. In this embodiment, for example, there are ten first controllers 16' in the low-load list. When estimating the connection quality assessment value, the second controller 20 estimates the connection quality between each highest-load gateway 14 and the ten first controllers 16' one by one, and each highest-load gateway 14 will generate ten corresponding connection quality assessment values.

[0046] The online quality assessment value can be estimated using the assessment value equation, which is shown below: , This is the online quality assessment value. and As weight, This is the upper limit of the load on the first controller 16'. The load value for one of the first controllers 16' in the low load list. The number of relay points connecting the highest-load gateway to one of the first controllers in the low-load list.

[0047] After calculating the connection quality assessment value of each gateway 14 with the highest load, proceed to step S24. The second controller 20 selects the first controller 16' with a high connection quality assessment value from the ten connection quality values ​​corresponding to the gateway 14 with the highest load, so as to transfer each gateway 14 with the highest load to the first controller 16' with the highest connection quality assessment value for management, thus completing the movement of gateway 14 in load balancing.

[0048] As described above, the present invention can effectively balance the load of controllers in the network, avoid controller overload, and improve the stability and reliability of the network system.

[0049] In summary, this invention meets the requirements for an invention patent, and therefore a patent application is filed in accordance with the law. However, the above description is merely a preferred embodiment of the invention, and the scope of the invention is not limited to the described embodiments. All equivalent modifications or variations made by those skilled in the art in accordance with the spirit of the invention should be covered within the scope of the following patent application.

Claims

1. A load balancing system for a software-defined wireless sensor network, characterized in that, include: A gateway connects multiple nodes, and the gateway has multiple transmission paths with the multiple nodes; The first controller manages the gateway and detects the load of the multiple transmission paths. When the ratio of the multiple transmission paths that are overloaded exceeds the ratio threshold, it issues an overload warning message. as well as The second controller connects to the first controller and receives the overload warning message. It adds the first controller that issued the overload warning message to the watchlist and stops transferring new gateways to the first controller in the watchlist.

2. The load balancing system for software-defined wireless sensor networks as described in claim 1, characterized in that, The second controller also receives load information from the first controller. When the load information of the first controller exceeds the load threshold, the second controller adds the first controller to the high load list; when the load information of the first controller is lower than the load threshold, the second controller adds the first controller to the low load list.

3. The load balancing system for software-defined wireless sensor networks as described in claim 2, characterized in that, The second controller selects the gateway with the highest load managed by the first controller in the high-load list; estimates the connection quality assessment value of the gateway with the highest load to each of the first controllers in the low-load list; And transfer the gateway with the highest load to the first controller that has the highest connection quality assessment value for management.

4. The load balancing system for software-defined wireless sensor networks as described in claim 3, characterized in that, The second controller also estimates the online quality assessment value using an evaluation value equation, which is shown below: ， The The online quality assessment value is the value described above. and the aforementioned As weight, the The load limit of the first controller, the The load value of one of the first controllers in the low load list, the The number of relay points from the highest-load gateway to one of the first controllers in the low-load list.

5. The load balancing system for software-defined wireless sensor networks as described in claim 2, characterized in that, The first controller also adjusts the reporting frequency of the load message to the second controller, the reporting frequency being adjusted according to a reporting frequency equation, which is shown below: ， For the said reward frequency, the For a point in time, the stated This can be expressed as the following equation: ， The The packet size output by the first controller, the The packet quantity input to the first controller, the The total number of packets input and output to the first controller.

6. A load balancing method for software-defined wireless sensor networks, characterized in that, Includes the following steps: The first controller detects the load on multiple transmission paths between the gateway and multiple nodes; When the ratio of the overloaded multiple transmission paths exceeds the ratio threshold, the first controller issues an overload warning message. Upon receiving the overload warning message, the second controller adds the first controller to the watchlist and stops transferring new gateways to the first controller in the watchlist for management.

7. The load balancing method for software-defined wireless sensor networks as described in claim 6, characterized in that, Also includes: The second controller receives the load information from the first controller. When the load information of the first controller exceeds the load threshold, the second controller adds the first controller to the high load list. When the load information of the first controller is lower than the load threshold, the first controller is added to the low load list.

8. The load balancing method for software-defined wireless sensor networks as described in claim 7, characterized in that, Also includes: The second controller selects the gateway with the highest load managed by the first controller from the high-load list; Estimate the connection quality assessment value of the gateway with the highest load for each of the first controllers in the low load list; and The gateway with the highest load is transferred to the first controller, which has the highest connection quality assessment value, for management.

9. The load balancing method for software-defined wireless sensor networks as described in claim 8, characterized in that, The step of estimating the connection quality assessment value further includes estimating the connection quality assessment value using an assessment value equation, which is shown below: ， The The online quality assessment value is the value described above. and the aforementioned As weight, the The load limit of the first controller, the The load value of one of the first controllers in the low load list, the The number of relay points from the highest-load gateway to one of the first controllers in the low-load list.

10. The load balancing method for software-defined wireless sensor networks as described in claim 7, characterized in that, Also includes: The first controller adjusts the reporting frequency of the load message to the second controller using the reporting frequency equation, which is shown below: ， For the said reward frequency, the For a point in time, the stated This can be expressed as the following equation: ， The The packet size output by the first controller, the The packet quantity input to the first controller, the The total number of packets input and output to the first controller.

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