Multi-topology routing in next-generation IoT networks

Abstract

A node device for forming a multi-hop network is provided. The node device is configured to discover two routing topologies: a normal routing topology for normal data transmission and a preferred topology for prioritized data transmission. The normal route is discovered for all data nodes in an IoT network, and the preferred route is discovered for only the preferred data nodes. The normal data route (D-route) is discovered using a distance-based route discovery protocol (RPL), and the preferred route (P-route) is optimally discovered for only the preferred data nodes to minimize route overlap, route transmission time, and route length. The node device includes a transceiver configured to transmit and receive normal data in a destination-oriented directed acyclic graph (DODAG)-based topology and transmit and receive priority data in the optimal routing topology; a memory configured to store a computer-executable program including a communication mode (CM), a multirate link count (MLC), a route overlap degree (DRO), neighbor node information, route transmission time, and route length; and a processor configured to execute the steps of the computer-executable program. The steps include finding a D route and finding a P route, where finding a P route includes finding a non-circular route, finding a minimum overlap route, finding a minimum transmission time route, and finding a minimum length route.

Description

Technical Field

[0001] The present invention generally relates to routing data in a wireless communication network, and more particularly to routing heterogeneous data in a next-generation wireless communication network.

Background Art

[0002] With the advent of 5G and subsequent communication technologies, consumer wireless devices are evolving from the current generation to the next generation. Next-generation wireless devices support multiple communication modes / interfaces and can perform more functions. In the transition phase, it is unrealistic to completely replace the deployed current-generation devices with next-generation devices. Therefore, next-generation wireless networks are composed of a mixture of current-generation nodes and next-generation nodes. Since existing routing protocols are typically designed for current-generation networks, there is a need to address how to efficiently route diverse data in next-generation wireless networks.

[0003] Therefore, it is desirable to provide a new routing architecture for transmitting diverse data in next-generation IoT networks.

Summary of the Invention

[0004] Some embodiments of the present invention are based on the recognition that consumer wireless devices are evolving from the current generation to the next generation, where current-generation devices support a single communication mode / interface and / or perform a single function, while next-generation devices support multiple communication modes / interfaces and / or can perform more functions. Devices that support a single communication mode are called single-mode, and devices that support multiple communication modes / interfaces are called multi-mode.

[0005] Some embodiments of the present invention are based on the recognition that, during the transition phase of consumer devices, it is impractical to replace all deployed current-generation devices with next-generation devices from a cost and service continuity standpoint.

[0006] To this end, one objective of various embodiments of the present invention is to form a next-generation wireless IoT network using a data concentrator and a mix of current-generation and next-generation nodes. The data concentrator is considered a multimode node, the current-generation node is a single-mode normal data node, and the next-generation nodes are classified into multimode normal data nodes, single-mode priority data nodes, and multimode priority data nodes. Current-generation nodes and next-generation multimode normal data nodes collect only normal data, while next-generation single-mode priority data nodes and next-generation multimode priority data nodes collect both normal and priority data. Nodes that collect only normal data are called D nodes, and nodes that collect both normal and priority data are called P nodes.

[0007] Some embodiments of the present invention are based on the recognition that in a multi-hop wireless network, route discovery is unavoidable because at least one data node cannot communicate directly with a data concentrator and must relay communication through other data nodes.

[0008] Therefore, various embodiments of the present invention form two routing topologies for next-generation IoT networks: a normal topology and a priority topology. The normal topology is used to transmit normal data, and the priority topology is used to transmit priority data. Normal routes in the normal topology are called D routes and are discovered for all data nodes using a distance-based method, while priority routes in the priority topology are called P routes and are discovered only for priority nodes to minimize route overlap, route transmission, and route length. D routes are less efficient, while P routes are more efficient.

[0009] Some embodiments of the present invention are based on the understanding that nodes in a next-generation IoT network may be single-mode nodes or multi-mode nodes. Single-mode nodes support a low-speed communication mode, while multi-mode nodes support both low-speed and high-speed communication modes. To support interoperability, the low-speed communication mode of a multi-mode node must be the same as the low-speed communication mode of a single-mode node.

[0010] Therefore, various embodiments of the present invention form slow and fast links in a routing topology. Slow links are formed between two single-mode nodes or between a single-mode node and a multi-mode node, while fast links are formed only between two multi-mode nodes.

[0011] Some embodiments of the present invention are based on the understanding that priority nodes in a next-generation IoT network can collect both normal and priority data. Priority data has a higher priority than normal data, and the transmission of priority data has a higher priority than the transmission of normal data.

[0012] Therefore, various embodiments of the present invention provide priority-based data routing such that, when a data node transmits or relays both normal data and priority data, it transmits priority data first. Thus, one object of various embodiments of the present invention is to provide a distributed D route discovery method and a centralized P route discovery method.

[0013] To this end, D-route discovery considers multimode nodes present in the next-generation IoT network. These nodes are organized as a destination-directed, directed, acyclic graph (DODAG) in the D-route topology. The mode of communication (CM) is included in the DODAG Information Object (DIO) message; CM=1 indicates a single-mode node, and CM=2 indicates a multimode node. Using the CM, the number of multimode links (MLC) can be calculated, representing the number of multimode links along the route. Routes with a smaller MLC consist of fewer multimode links, and routes with a larger MLC consist of more multimode links. All other conditions being equal, the data node will select the route with the larger MLC. Additionally, the cumulative traffic load (ATL) is included in the Destination Advertisement Object (DAO) message, and the route communication time (RCT) can be calculated using the ATL parameter. All other conditions being equal, the data node will select the route with the smaller RCT.

[0014] Some embodiments of the present invention are based on the recognition that route overlap can delay data transmission and cause data loss. P-route discovery depends on the number of nodes in the network, the number of preferred nodes, and the node arrangement. It is not always possible to discover P-routes without overlap. However, P-route overlap can be minimized.

[0015] To achieve this, the optimal P-route is found to minimize objectives such as route overlap, route transmission time, and route length. Therefore, a method for calculating the degree of route overlap is needed. However, existing route overlap calculation methods are defined for point-to-point (P2P) routing and are not suitable for multi-point-to-point (MP2P) routing. In MP2P routing, all routes have the same destination node, and since this destination node does not transmit data, it should not be counted in the route overlap calculation.

[0016] One objective of several embodiments is to define the route overlap of an MP2P route as the sum of the overlaps of each forwarding node caused by the route. A forwarding node is a node on the route that transmits or relays data. Mathematically, route overlap is the total number of times the route repeatedly passes through a forwarding node.

[0017] Some embodiments of the present invention are based on the recognition that circular routes are inefficient because they have longer latency, waste communication bandwidth and node resources, and can interfere with other routes. Therefore, non-circular P routes must be discovered.

[0018] Accordingly, some embodiments of the present invention provide a recursive acyclic route discovery method for discovering acyclic routes from a priority node to a data concentrator in a next-generation IoT network. Recursive acyclic route discovery starts from a priority node and extends the route hop by hop until the route reaches a data concentrator or until the route can no longer be extended without recursion.

[0019] Some embodiments of the present invention are based on the understanding that the maximum number of non-overlapping routes is equal to the number of physical neighboring nodes of the data concentrator.

[0020] To this end, the objective of some embodiments is to find the P-route of preferred nodes in such a way as to minimize root overlap. P-route discovery is formulated as a nonlinear optimization problem.

[0021] According to some embodiments of the present invention, a node device is provided for use in a multi-hop heterogeneous wireless network including single-mode nodes and multi-mode nodes. The node device comprises a transceiver configured to send and receive messages to discover a normal data route (D route), the discovered D route forming a destination-directed directed acyclic graph (DODAG) topology, and the transceiver is configured to send and receive normal data in the destination-directed directed acyclic graph (DODAG) topology and to send and receive preferred data in the optimal routing topology. The node device comprises a computer-executable program, a memory configured to store DODAG topology configuration parameters including a rank specified by the Internet Protocol version 6 (IPv6) routing protocol for low-power and lossy network (RPL) protocols, a communication mode (CM), and a multi-rate link count (MLC), and a processor configured to execute steps of the computer-executable program. The step involves discovering D routes for all data nodes to form a DODAG topology using the IPv6 routing protocol for Low Power and Lossy Network (RPL) protocols, which uses DODAG Information Object (DIO) messages to perform the uplink route discovery process and Destination Advertisement Object (DAO) messages to perform the downlink route discovery process. The step involves discovering neighbor nodes along with the D routes, and the processor determines other nodes as neighbor nodes if it receives a DIO message broadcast from another node via the transceiver. The step involves using the transceiver to send the cumulative traffic load (ATL) and identifier of neighbor nodes to the data concentrator via a DAO message.

[0022] Furthermore, some embodiments of the present invention provide a node device for use in a multi-hop heterogeneous wireless network including a multimode concentrator. The node device comprises a transceiver configured to transmit a destination-directed acyclic graph (DODAG) information object (DIO) message to initiate normal data route (D route) discovery, receive a destination advertisement object (DAO) message to constitute a downlink normal data route (D route), and obtain the cumulative traffic load (ATL) and neighbor node information of a data node to perform optimal preferred route (P route) discovery to construct an optimal routing topology, the transceiver configured to transmit the optimal routing topology to data nodes on the discovered preferred route (P route) in order to transmit preferred data to the multimode concentrator, the transceiver configured to receive normal data in the DODAG topology and preferred data in the optimal routing topology. The node device comprises a computer-executable program and a memory configured to store parameters including a communication mode (CM), ATL, neighbor node set, route overlap degree (DRO), and optimal preferred route (P route) discovery, and a processor configured to execute steps of the computer-executable program. The step involves discovering D routes for all data nodes using the Internet Protocol version 6 (IPv6) routing protocol for low-power and lossy network (RPL) protocols, which uses DIO messages to perform the uplink route discovery process and Destination Advertisement Object (DAO) messages to perform the downlink route discovery process. The step involves discovering the optimal preferred route (P route) by formulating the P route discovery problem as a nonlinear optimization problem to minimize route overlap calculated using DRO, and the discovered optimal P route is further optimized to minimize route transmission time and route length.

[0023] Some embodiments are based on the recognition that the minimum overlap route discovery problem can be a multiple solution problem where a set of multiple P-routes can minimize route overlap.

[0024] To that end, some embodiments of the present invention provide a method for obtaining a set of minimum overlap P-routes so as to minimize the total route transmission time.

[0025] Furthermore, some embodiments of the present invention also provide a method for obtaining a set of minimum overlap P-routes so as to minimize the total route length.

[0026] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. The drawings are not necessarily drawn to scale. Instead, the drawings may be emphasized to illustrate the principles of the embodiments of the present disclosure.

Brief Description of the Drawings

[0027] [Figure 1] It is a schematic diagram showing a next-generation wireless IoT network including a data concentrator and a mixed current-generation nodes and next-generation nodes. [Figure 2] It shows the node classification in the next-generation wireless IoT network, where the data concentrator is a multi-mode node, the current-generation nodes are usually single-mode nodes, and the next-generation nodes include multi-mode normal nodes, priority single-mode nodes, and priority multi-mode nodes. [Figure 3] It is a diagram showing an example of a 2-topology routing architecture in the next-generation wireless IoT network. [Figure 4] It is a diagram showing an example of a loop route and a non-loop route in the next-generation wireless IoT network. [Figure 5] It is a diagram showing an example of a sub-route on the route from a priority node p to a data concentrator C in a multi-point to point (MP2P) routing topology in the next-generation wireless IoT network. [Figure 6]This figure shows an example of end nodes and non-end nodes when a non-circular P-route is discovered in a next-generation wireless IoT network. [Figure 7] This diagram shows the sub-route extension and expansion of priority nodes when a non-circular P-route is discovered in a next-generation wireless IoT network. [Figure 8A] This figure shows an algorithm for setting up acyclic route discovery for preferred nodes in a next-generation wireless IoT network. [Figure 8B] This figure shows an algorithm for recursively extending and expanding acyclic subroutes of priority nodes in a next-generation wireless IoT network. [Figure 9] This is an algorithm for discovering the minimum overlapping route for all priority nodes in a next-generation wireless IoT network. [Figure 10] This diagram shows the time allocation for priority data transmission and normal data transmission in a next-generation wireless IoT network. [Modes for carrying out the invention]

[0028] The drawings described above illustrate embodiments of the present disclosure, but other embodiments are also conceivable, as discussed above. This disclosure provides exemplary embodiments and is not limiting. Those skilled in the art can devise many other modifications and embodiments that fall within the scope and spirit of the principles of the embodiments of this disclosure.

[0029] In current-generation IoT networks, devices are typically installed with fewer resources and perform simpler functions. For example, these devices use battery power, support the IEEE 802.15.4 communication protocol, and transmit data using the FSK modulation scheme. Next-generation IoT networks, on the other hand, typically include a mix of current-generation and next-generation devices. Next-generation devices are equipped with more resources and can perform more functions. For example, next-generation devices use grid power, support both the IEEE 802.15.4 and LTE / 5G communication protocols, and use both FSK and QAM modulation schemes. Therefore, next-generation devices in a next-generation IoT network can perform multiple roles. For example, consider a next-generation smart meter network that includes both current-generation and next-generation meters. Current-generation meters only collect metering data and periodically transmit it to a data concentrator. However, next-generation meters can either 1) collect both metering data and power supply information, or 2) support multiple communication modes / interfaces, or 3) collect both metering data and power supply information while also supporting multiple communication modes / interfaces. Power supply information is transmitted via last gasp messages and is crucial for power suppliers to perform predictive maintenance on smart meter networks and diagnose the causes of abnormal events such as power outages. Therefore, it has a higher priority than regular metering data. Next-generation meters that collect power supply information are called priority meters. Consequently, priority meters need to efficiently transmit event-based last gasp messages in addition to the regular transmission of metering data.

[0030] In next-generation IoT networks, nodes may be classified based on different criteria, such as (1) their role as a data source or data destination, (2) their communication capabilities, and (3) their data collection capabilities. Based on criterion 1), nodes that collect data are called data nodes, and nodes that aggregate data are called data concentrators. Based on criterion 2), nodes that support one communication mode are called single-mode nodes, and nodes that support multiple communication modes / interfaces are called multi-mode nodes. In particular, data concentrators are multi-mode nodes. Based on criterion 3), nodes that collect only normal data are called normal nodes, and nodes that collect both normal and priority data are called priority nodes.

[0031] Figure 1 is a schematic diagram showing a next-generation wireless IoT network including a data concentrator 100, current-generation single-mode normal data nodes 110, next-generation multi-mode normal data nodes 120, next-generation single-mode priority data nodes 130, and next-generation multi-mode priority data nodes 140. These nodes form a multi-hop mesh network. Normally, data packets are sent from data nodes (current-generation or next-generation nodes) to the data concentrator 100, but control messages can be sent in either direction. Since at least one data node cannot communicate directly with the data concentrator 100, communication must be relayed via an intermediate node. Single-mode nodes can only support low-speed communication mode. However, multi-mode nodes can support both low-speed and high-speed communication modes. As a result, a low-speed link 150 is formed by two single-mode nodes or by a single-mode node and a multi-mode node. On the other hand, a high-speed link 160 is formed by only two multi-mode nodes. The single-mode nodes include the current-generation normal data node 110 and the next-generation single-mode priority data node 130. The multimode node includes a next-generation multimode normal data node 120, a next-generation multimode priority data node 140, and a data concentrator 100.

[0032] Figure 2 shows the node classification in the next-generation wireless network. Nodes in the next-generation IoT network 200 are first classified into data nodes 210 and data concentrators 220. The data concentrators 220 are considered as multimode nodes 230. The data nodes 210 are further classified into current-generation data nodes 240 and next-generation data nodes 260. The current-generation data nodes 240 are classified as single-mode normal data nodes 250, and the next-generation data nodes 260 are classified into multimode normal data nodes 270, single-mode preferred data nodes 280, and multimode preferred data nodes 290.

[0033] Routing is essential for transmitting data in multi-hop IoT networks. Routing has been extensively studied for many years. The concept of routing is simple. However, the routing problem is a highly complex problem consisting of two steps: route discovery and routing scheduling. Route discovery can be an NP-complete problem. For example, maximizing the throughput of a multi-hop wireless network has been proven to be NP-hard due to the effects of radio interference. Furthermore, both centralized and distributed routing scheduling problems have been proven to be NP-complete in 2D mesh topologies, further increasing the complexity of the routing scheduling problem.

[0034] Well-known route discovery protocols include Dijkstra's shortest route algorithm, Dynamic Source Routing (DSR), Ad Hoc On-Demand Distance Vector (AODV), and the Internet Protocol version 6 (IPv6) routing protocol for low-power and lossy networks (RPL). However, these routing protocols are not designed to handle heterogeneous data and heterogeneous nodes. For example, RPL sends all uplink traffic to a default parent node and uses the same network configuration parameters for all nodes. Therefore, the challenges arising in next-generation IoT networks need to be addressed.

[0035] To ensure the efficient functioning of next-generation IoT networks, many issues must be addressed. Route overlap is one such issue, particularly when transmitting priority data. Route overlap can have a significant impact on network performance. In wireless networks, route overlap can delay data transmission and cause data loss. Therefore, to improve the reliability of priority data transmission, route overlap, especially the overlap of routes used to transmit priority data, must be minimized.

[0036] This invention provides a two-topology routing architecture for next-generation IoT networks, namely a normal topology used for normal data transmission and a priority topology used for priority data transmission. Routes in the normal topology are called normal data routes (D routes), and routes in the priority topology are called priority routes (P routes). D routes are discovered for all data nodes in the network. However, P routes are discovered only for priority data nodes. D routes are discovered using methods based on conventional protocols. However, P routes are discovered using the optimal method of this invention, which formulates P route discovery as an optimization problem. Therefore, P routes are the optimal routes that minimize route overlap, route transmission time, and route length.

[0037] Figure 3 shows an example of a two-topology routing architecture for a next-generation IoT network, including a data concentrator C, two next-generation multimode normal data nodes 1 and 5, three next-generation single-mode priority data nodes 2, 6, and 14, and ten current-generation single-mode data nodes 3, 4, 7, 8, 9, 10, 11, 12, 13, and 15. Route 300, indicated by a dashed arrow, represents a D route in the routing topology for transmitting normal data. These distance-based routes are discovered using the conventional RPL protocol. Route 310, indicated by a solid arrow, represents a P route in the routing topology for transmitting priority data. These routes are discovered using the optimal method provided by the present invention. The routes for priority data nodes 2, 6, and 14 are different in the two topologies. In the normal topology, routes 2→C, 6→2→C, and 14→9→3→C overlap at node 2. However, in the priority topology, routes 2→C, 6→5→1→C, and 14→9→3→C do not overlap. Also, links 5→1 and 1→C are high-speed links. Route P uses these high-speed links. However, Route D does not have these high-speed links. Assuming a PHY data transfer rate of 100kbps in slow communication mode and a PHY data transfer rate of 800kbps in high communication mode, the slow link takes 8ms to send a 100-byte packet. However, the high-speed link takes only 1ms. Furthermore, IoT devices are typically half-duplex. Considering radio link interference and ignoring random backoff delays, Route D takes 32ms to send three priority data packets. Route P, on the other hand, takes only 26ms. These results indicate that Route P, although potentially longer, is more efficient. The necessity of multi-topology routing

[0038] With the emergence of 5G and subsequent communication technologies, consumer IoT devices are evolving from the current generation to the next generation. Current-generation devices are installed with fewer resources and perform simpler functions. For example, current-generation devices support one communication mode (called single-mode devices) and collect normal data. Next-generation devices, on the other hand, are equipped with more resources and perform more functions. For example, next-generation devices support multiple communication modes / interfaces (called multi-mode devices) and / or can collect both normal data and priority data (called priority devices). However, during the transition phase, it is impractical to completely remove deployed current-generation devices. For example, consider a next-generation smart meter network that includes current-generation normal meters and next-generation priority meters. Normal meters collect and transmit metering data periodically. Priority meters, on the other hand, not only collect normal metering data but also detect power supply information. This information is important for power suppliers to perform predictive maintenance and diagnose the causes of abnormal events such as power outages, and therefore has a higher priority than normal metering data. Thus, priority meters need to efficiently transmit power supply information in addition to normal metering data. Therefore, a new routing architecture is needed for transmitting heterogeneous data in next-generation IoT networks. To that end, it is necessary to address how to efficiently route diverse data in next-generation IoT networks.

[0039] While routing for current-generation IoT networks has been extensively studied, routing for next-generation IoT networks has not yet been sufficiently researched. This invention provides a two-topology routing architecture for next-generation IoT networks, namely a normal topology used for normal data transmission and a priority topology used for priority data transmission. Routes in the normal topology are called D routes, and routes in the priority topology are called P routes. Data nodes that collect only normal data are called D nodes, and data nodes that collect both normal and priority data are called P nodes. D routes are discovered for all data nodes in the network. However, P routes are discovered only for priority data nodes. D routes are discovered using distance-based methods. However, P routes are discovered using optimal methods that formulate route discovery as an optimization problem. Therefore, P routes are the optimal routes that minimize route overlap, route transmission time, and route length.

[0040] Embodiments of the present invention consider a next-generation IoT network comprising a data concentrator, a set of N normal data nodes called D nodes, and a set of M preferred data nodes called P nodes. Both D nodes and P nodes may be single-mode or multi-mode. The data concentrator is considered a multi-mode node. Communication between single-mode nodes and between single-mode nodes and multi-mode nodes uses a slow mode. A fast mode may be applied only to communication between multi-mode nodes. The arrangement of D nodes and P nodes is random. Discovery of a distributed D-route

[0041] Embodiments of the present invention enhance the RPL routing protocol for discovering D routes. RPL discovers uplink routes using DODAG Information Object (DIO) messages and downlink routes using Destination Advertisement Object (DAO) messages. To discover P routes, each data node performs neighbor node discovery while discovering D routes. Another node that receives a DIO message broadcast from one node is considered a neighbor node of that node. Once D route discovery is complete, each data node sends neighbor node information to the data concentrator via a DAO message.

[0042] Communication mode and number of multimode links included in the DIO message The DIO message contains information for a node to obtain DODAG configuration parameters for performing parent node selection, i.e., route selection. In this invention, the communication mode (CM) and the number of multimode links (MLC) are also included in the DIO message. CM=1 indicates single mode, and CM=2 indicates multimode. Using the CM parameter, the MLC metric, which represents the number of multimode links along the route, i.e., the number of high-speed links along the route, can be calculated. For a data concentrator, CM=2 and MLC=0. During D-route discovery, the data node increments MLC by 1 only if the data node itself is a multimode node and the DIO message transmitter is also a multimode node. The data node selects a parent node using the RPL rank metric and the MLC metric. If the ranks of candidate parent nodes are the same, the data node selects the route with the higher MLC value, because the route with the higher MLC value contains more high-speed links. Rank is a distance-based metric that represents the node's position relative to the concentrator in the DODAG topology. A lower rank value indicates that the node is closer to the concentrator, while a higher rank value indicates that the node is further away from the concentrator.

[0043] DAO messages include cumulative traffic load, neighbor node information, and communication mode. Traffic load can have a significant impact on network performance. However, this problem is not adequately addressed in the RPL routing protocol. In this invention, cumulative traffic load information for each data node is included in the DAO message. In the RPL protocol, data nodes not only transmit their own data but also relay data from child nodes to the default parent node. Therefore, the cumulative traffic load (ATL) of data node n is shown as follows:

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[0044]

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[0045] There are different definitions of route overlap. One prior art defines link (edge) overlap as route overlap. However, this definition can underestimate route overlap. For example, in Figure 3, routes (11,5,1,C) and (12,5,2,C) overlap at node 5, but there is no link overlap between these two routes. Another prior art defines route overlap as the sum of all individual node overlaps between any two routes. This node-based P2P routing overlap definition can overestimate MP2P route overlap. For example, since data concentrator C does not transmit data, the two aforementioned routes have only one valid node overlap at node 5, but this definition gives two overlaps: one at node 5 and another at node C.

[0046]

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[0047] Circular routes are inefficient. Figure 4 shows examples of non-circular and circular routes. Route (12,6,7,3,C)400 is a non-circular route, and since 5→1→4→5 is circular, route (11,5,1,4,5,2,C)410 is a circular route.

[0048]

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[0049]

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[0050] Figure 5 shows the preferred node p in the multipoint-to-point (MP2P) routing topology in the next-generation wireless IoT network. n An example of sub-route 500 on the P-route from data concentrator C is shown.

[0051] Before introducing the recursive acyclic route discovery algorithm, we first define the end nodes.

[0052] definition An end node is a data node where the extension of a non-cyclic subroot ends; in other words, a subroot cannot be extended without a cycle.

[0053] End nodes are different from leaf nodes. An end node is a leaf node, but a leaf node is not necessarily an end node. Whether a node is an end node depends on the subroot being extended. A node may be an end node when extending one subroot, but not when extending another subroot. In Figure 6, when extending subroot (10,4), node 11 is not an end node, but when extending subroot (4,5), node 11 is an end node.

[0054]

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[0055]

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[0056]

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[0059] Problem (3) is a nonlinear optimization problem that can be particularly difficult to solve for large, high-density networks with many acyclic routes. In fact, problem (3) belongs to the category of combinatorial optimization problems and is weakly NP-hard.

[0060]

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[0061] Problem (3) may be a multi-solution problem. For example, in Figure 3, routes (2,C), (6,5,1C) and (14,9,3C) and routes (2,C), (6,5,4,1C) and (14,8,3C) are two sets of routes with zero overlap. Therefore, the minimum overlap route may be further optimized based on other metrics such as route transmission time and route length. In a network without multimode nodes, the route with the minimum length may give the minimum transmission time. However, if multimode nodes are present, these two objectives may lead to different solutions. Finding the P route with the shortest transmission time

[0062]

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[0065]

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[0066] After concentrator C discovers a preferred route for transmitting preferred data, it transmits the preferred route not only to the preferred node but also to the regular nodes. As a result, the preferred node is aware of the P route to which the preferred data is transmitted, and all nodes in the network are aware of the P route to which the preferred data is relayed.

[0067] A data node may transmit or relay both regular and priority data simultaneously. In this case, the data node will first transmit or relay the priority data using the priority route. This indicates that the priority route has higher priority than the regular route. Priority data transmission time allocation by data concentrator

[0068] Priority data has a higher priority than regular data. However, regular data transmission competes for resources with priority data transmission, potentially delaying priority data. Therefore, data concentrator C can divide time into periods, as shown in Figure 10. Priority period (PP) 1000 is used only for priority data transmission, and data period (DP) 1010 is used for both regular and priority data transmission. Data concentrator C can transmit such period information to all data nodes in the network.

[0069] The above description provides only exemplary embodiments and is not intended to limit the scope, application, or configuration of the present disclosure. Rather, the following description of exemplary embodiments will give a person skilled in the art an explanation that will enable the implementation of one or more exemplary embodiments. Various modifications to the function and arrangement of the elements are possible without departing from the spirit and scope of the subject matter set forth in the appended claims.

[0070] While this disclosure describes the present invention as an example of preferred embodiments, it should be understood that various other adaptations and modifications can be made within the spirit and scope of the invention. Therefore, the purpose of the appended claims is to cover all variations and modifications that fall within the true spirit and scope of the invention.

Claims

1. A node device used in a multi-hop heterogeneous wireless network including single-mode nodes and multi-mode nodes, The node device comprises a transceiver configured to send and receive messages to discover a normal data route (D route), the discovered D route forming a destination-directed directed acyclic graph (DODAG) topology, the transceiver configured to send and receive normal data in the destination-directed directed acyclic graph (DODAG) topology and to send and receive priority data in the optimal routing topology, and the node device is configured A memory configured to store a computer-executable program, the rank specified by the Internet Protocol version 6 (IPv6) routing protocol for low-power and lossy network (RPL) protocols, and DODAG topology configuration parameters including the communication mode (CM) and the number of multi-rate links (MLC), A processor configured to execute steps of the aforementioned computer-executable program, The aforementioned step is, The IPv6 routing protocol for low-power and lossy network (RPL) protocols includes discovering the D routes for all data nodes included in the multi-hop heterogeneous wireless network to form the DODAG topology, wherein the RPL protocol uses DODAG Information Object (DIO) messages to perform the uplink route discovery process and uses Destination Advertisement Object (DAO) messages to perform the downlink route discovery process. The process includes discovering the D route and discovering neighboring nodes, and when the processor receives a DIO message broadcast from another node via the transceiver, it determines that the other node is a neighboring node. This includes using the transceiver to transmit the cumulative traffic load (ATL) and identifier of the neighboring node to the data concentrator via the DAO message, The DIO message includes parameters specified by the RPL protocol and other parameters for selecting a parent (root) from the DODAG topology. The DIO message includes the rank specified by the RPL protocol, the CM, and the MLC, The aforementioned CM is used to calculate the aforementioned MLC, The aforementioned MLC is used to select a root, and if the ranks of the parent candidates are the same, the data node selects the root with the larger MLC, node device.

2. The data concentrator and the multimode node set the CM to 2, and the singlemode node sets the CM to 1. The node device according to claim 1, wherein, if the data node is a multimode node and the transmitter of the DIO message is a multimode node, the data concentrator sets the MLC to 0 and the data node increments the MLC by 1. 【Request Item 3】 【Number 1】

4. The node device according to claim 1, wherein if the data node has both the normal data and the priority data, it transmits the priority data first.

5. A node device used in a multi-hop heterogeneous wireless network including single-mode nodes and multi-mode nodes, The node device comprises a transceiver configured to send and receive messages to discover a normal data route (D route), the discovered D route forming a destination-directed directed acyclic graph (DODAG) topology, the transceiver configured to send and receive normal data in the destination-directed directed acyclic graph (DODAG) topology and to send and receive priority data in the optimal routing topology, and the node device is configured A memory configured to store a computer-executable program, the rank specified by the Internet Protocol version 6 (IPv6) routing protocol for low-power and lossy network (RPL) protocols, and DODAG topology configuration parameters including the communication mode (CM) and the number of multi-rate links (MLC), A processor configured to execute steps of the aforementioned computer-executable program, The aforementioned step is, The IPv6 routing protocol for low-power and lossy network (RPL) protocols includes discovering the D routes for all data nodes included in the multi-hop heterogeneous wireless network to form the DODAG topology, wherein the RPL protocol uses DODAG Information Object (DIO) messages to perform the uplink route discovery process and uses Destination Advertisement Object (DAO) messages to perform the downlink route discovery process. The process includes discovering the D route and discovering neighboring nodes, and when the processor receives a DIO message broadcast from another node via the transceiver, it determines that the other node is a neighboring node. This includes using the transceiver to transmit the cumulative traffic load (ATL) and identifier of the neighboring node to the data concentrator via the DAO message, [Math 2] Node device.

6. The data concentrator and the multimode node set the CM to 2, and the singlemode node sets the CM to 1. The node device according to claim 5, wherein, if the data node is a multimode node and the transmitter of the DIO message is a multimode node, the data concentrator sets the MLC to 0 and the data node increments the MLC by 1.

7. The node device according to claim 5, wherein if the data node has both normal data and priority data, it transmits the priority data first.

8. A node device used in a multi-hop heterogeneous wireless network including a multimode concentrator, A transceiver is provided which is configured to send a destination-directed acyclic graph (DODAG) information object (DIO) message to initiate normal data route (D route) discovery, receive a destination advertisement object (DAO) message to constitute a downlink normal data route (D route), and obtain the cumulative traffic load (ATL) and neighbor node information of a data node to perform optimal preferred route (P route) discovery to construct an optimal routing topology, wherein the transceiver is configured to send the optimal routing topology to the data node on the discovered preferred route (P route) in order to send preferred data to the multimode concentrator, the transceiver is configured to receive normal data in the DODAG topology and preferred data in the optimal routing topology, and the node device is configured A computer-executable program and a memory configured to store parameters including the communication mode (CM), the ATL, the neighbor node set, the degree of route overlap (DRO), and the discovery of the optimal preferred route (P-route), A processor configured to execute steps of the aforementioned computer-executable program, The aforementioned step is, The process includes discovering the D-routes for all data nodes in the multi-hop heterogeneous wireless network using the Internet Protocol version 6 (IPv6) routing protocol for low-power and lossy network (RPL) protocols, wherein the RPL protocol uses the DIO message to perform the uplink route discovery process and the Destination Advertisement Object (DAO) message to perform the downlink route discovery process. A node device that includes finding the optimal preferred route (P-route) by formulating the P-route discovery problem as a nonlinear optimization problem in order to minimize the route overlap calculated using the DRO, wherein the discovered optimal P-route is further optimized to minimize the route transmission time and route length.

9. The discovery of the aforementioned P route was, Using the acyclic route discovery method that identifies the acyclic routes of priority nodes in the multi-hop heterogeneous wireless network, the acyclic route of each priority node is discovered. The minimum overlap P-route in the multi-hop heterogeneous wireless network is discovered by solving a nonlinear optimization problem using a minimum overlap P-route discovery method. By solving a nonlinear optimization problem, the set of minimum overlapping P routes that minimizes the total route transmission time of the multi-hop heterogeneous wireless network is discovered. The node device according to claim 8, comprising finding the set of minimum overlap R routes that minimize the total route length of the multi-hop heterogeneous wireless network by solving a nonlinear optimization problem. [Request Item 10] [Number 3] [Request Item 11] [Number 4]

12. The aforementioned discovery of a non-circular route is, To construct a one-hop acyclic route for the preferred node, which is a neighboring node of the concentrator, The node device according to claim 9, comprising discovering a set of acyclic routes for the preferred node that is not a neighboring node of the concentrator, using a recursive extension and extension method for recursively extending and expanding each subroute starting from the preferred node, wherein each subroute is a partial route that has not yet reached the concentrator.

13. The recursive extension and expansion of the aforementioned subroots are as follows: To construct a single one-hop subroute from the aforementioned preferred node to each neighboring node, The node device according to claim 12, comprising: recursively extending and expanding each one-hop subroutine until the subroutine reaches a concentrator; deleting the subroutine if it cannot be extended without a cycle; or expanding the subroutine if it can be extended to a plurality of extendable nodes. [Request Item 14] [Number 5] [Request Item 15] [Number 6] [Request Item 16] [Number 7] [Request Item 17] [Number 8] [Request Item 18] [Number 9] [Request Item 19] [Number 10] [Request Item 20] [Number 11]

21. The concentrator transmits the discovered optimal priority route (the P route) to the data node on the P route for priority data transmission. The normal data node on the P route relays the priority data using the P route. The node device according to claim 8, wherein the priority node transmits or relays the priority data using the P route.

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