Methods and routing systems for routing movable nodes in a communication network

Abstract

A method performed by a routing system (200) is provided. The routing system (200) comprises a movable node (202), at least one mesh node (204) and one border node (208). Each mesh node (204) and border node (208) have a respective memory (1006, 1106). The method comprises: sending (310), by a movable node (202), a post message to a parent node, the parent node being a mesh node (204) or a border node (208). When the parent node is a mesh node (204), the method further comprises storing (312), in the mesh node (204), timing information in the memory (1006) of the mesh node (204), wherein the stored (312) timing information being deleted when the memory (1006) is full; forwarding (314), through the mesh node (204), the post message towards the border node (208); and storing (316), in the border node (208), routing information in the memory (1106) of the border node (208), wherein the stored (316) routing information being deleted when the memory (1106) is full. When the parent node is a border node (208), the method further comprises storing (322), by the border node (208), timing information and routing information in the memory (1106) of the border node (208), wherein the stored (322) timing and routing information being deleted when the memory (1106) is full.

Description

METHODS AND ROUTING SYSTEMS FOR ROUTING MOVABLE NODES IN A COMMUNICATION NETWORKTechnical Field

[0001] The present disclosure relates generally to methods and routing systems for routing movable nodes in a communication network. The present disclosure also relates generally to mesh nodes in the communication network and methods performed by the mesh nodes. The present disclosure also relates to border nodes in the communication network and methods performed by the border nodes. Background

[0002] Nowadays different types of communication network technologies are being used or developed. The internet of things (loT) is one of the communication networks which is being developed rapidly. The loT describes physical objects with sensors, processing ability, software and other technologies that connect and exchange data with other devices and systems over the Internet or other communication networks. The loT can be low-power and lossy networks.

[0003] Routing Protocol for Low-Power and Lossy Networks (RPL) is the standard protocol for low-power IPv6 routing defined by the IETF as RFC6550. In networks using RPL, the network nodes can be categorized into three types. The first type is a movable node. This type of node has little storing and communicating capacity and moves freely and flexibly in the network. When the movable node moves within the network, it keeps on connecting and disconnecting with other network nodes. When connecting with another node, the movable node can send / receive messages to / from another node. However, the connecting time can be quite short, e.g., several seconds. When disconnecting with other nodes, the movable node may be inactive or hibernate. For example, the movable node can be a communication tag which has basic communication functions and moves rapidly in the network. The tag can connect with any of the nodes in the network, then disconnect with the node within short time periods. After disconnecting with the node, the tag can connect with a further node or hibernate.

[0004] The second type of node is a mesh node. This type of node has basic communicating and calculating capacity. The mesh node also includes a memorywhich can store related information when routing messages in the network. The mesh node does not move so freely as the movable node, and acts as intermediate nodes when routing messages.

[0005] The third type of node is a border node. The border node acts as a root router in the network. Since it works as a root router, according to RPL, the border node keeps an overall routing table relating to all the routes that are routed by the border node. However, before the movable node connects to a parent node and sends any information to the border node via the parent node, the border node does not have any knowledge about the connection between the movable node and the parent node of the movable node. Therefore, when the movable node connects to a parent node, the movable node needs to inform related information to the border node.

[0006] Referring to fig. 1a, a typical communication network, i.e. , low-power and lossy network, is shown. In this communication network, node 102 is a movable node, which moves promptly, and connects / disconnects with other nodes flexibly. The movable node 102 can also send and receive messages when connecting with other nodes. The nodes 104 and 106 are mesh nodes which can receive / forward messages and store related information in its memory. The node 108 is a border node. The border node 108 can receive messages forwarded by the mesh node 106 and store related information in its memory. The border node 108 can also send reply towards the movable node 102. In this scenario, the movable node 102 connects with a mesh node 104.

[0007] In prior art, the movable node 102 proactively probes with a predetermined frequency, e.g., probes every few minutes. When probing, the movable node 102 detects its parent node and verifies that the connection between the movable node 102 and its parent node still exists. If the movable node 102 probes that the connection between the movable node 102 and its parent node degrades, the movable node 102 may consider changing to another parent node. The movable node 102 also registers a parent node with a predetermined frequency, e.g., registers every 30 minutes. When registering the parent, since the movable node 102 is connected to the mesh node 104, the movable node 102 sends a Destination Advertisement Object (DAO) to its parentnode, which is the mesh node 104. Frequency hopping (FH) technique is used by the movable node 102, that is, the movable node 102 transmits data on different frequency channels in different time periods. For example, there are 5 available frequencies f1-f5, and the movable node 102 transmits data in the 5 available frequencies in different time periods, one frequency for one time period, e.g., f5, f3, f2, f4, f1 . Therefore, the “f5, f3, f2, f4, f1” and the time period information is a frequency hopping sequence. In RPL or other communication network, the FH technique can be Wireless Smart Utility Network (Wi-Sun) FH technique. FH timing information of the movable node 102 is included in the DAO and sent to the mesh node 104. The FH timing information of the movable node 102 can be a timestamp which indicating the time when the movable node 102 started its frequency hopping sequence. Therefore, the mesh node 104 knows the frequency used by the movable node 102 for transmitting data at a given time, based on the received FH timing information and predefined frequency hopping sequence.

[0008] When the mesh node 104 receives the DAO sent from the movable node 102, the mesh node 104 stores the FH timing information contained in the DAO in its main memory as an FH entry. Then the mesh node 104 forwards the DAO towards the border node 108, i.e. , via another mesh node 106. The mesh node 106 continues to forward the DAO to the border node 108.

[0009] When the border node 108 receives the DAO, it stores routing information as a routing entry in a routing table stored in its main memory. The routing information relates to the route between the movable node 102 and its parent node, that is the route between the movable node 102 and the mesh node 104.

[0010] Referring to fig. 1 b, after probing / registering, the movable node 102 performs a post step. In this post step, the movable node 102 sends a post message to its parent node, which is the mesh node 104. When the mesh node 104 receives the post message, it forwards the post message towards the border node 108, i.e., via another mesh node 106. The post message reaches the border node 108 at last.

[0011] As shown in the fig. 1c, after receiving the post message, the border node 108 sends a reply back to the movable node 102, via the stored route entryin the routing table, that is the routing information relates to the route between the movable node 102 and its parent node 104.

[0012] Fig. 2 shows an interaction diagram of a routing system. The routing system includes at least the movable node 102, the mesh node 104 and the border node 108. In step 2.1 , the movable node 102 probes to its parent node, that is the mesh node 104. In step 2.2, the movable node 102 registers its parent, that is to send a DAO to the mesh node 104. The mesh node 104 stores FH timing information in its memory in step 2.3. The FH timing information is contained in the DAO sent in step 2.2. In step 2.4, the mesh node 104 forwards the DAO towards the border node 108. In step 2.5, when receiving the DAO, the border node 108 stores the route related to the movable node 102 and the mesh node 104. Thus, the probe and registration of the movable node 102 is finished. In step 2.6, the movable node 102 sends a post message towards the border node 108 via the mesh node 104. In step 2.7, the border node 108 sends a reply message towards the movable node 102. The reply message is sent based on the route stored in step 2.5.

[0013] According to the above solution, every time a movable node connects to a parent node, the parent node stores FH timing information, and the border node stores the related route. The information stored in the memories of the mesh nodes and the border nodes will be kept for a long time even after the movable node disconnects with its parent node and / or hibernates. Since the scale of the network can be very large, e.g., thousands of movable nodes, and the movable nodes connect / disconnect with other nodes quickly, resulting in that the topology / routing of the network changes quickly, the burden of the memories of the mesh nodes and border nodes becomes quite large after a period. Furthermore, when the movable node is disconnected with the current parent node, the related information stored in the memories of mesh nodes and border nodes becomes invalid information. However, the invalid information still remains in the memories without being deleted. Thus, the invalid information occupies extensive resources for a long time and reduces the efficiency of the whole network.

[0014] Therefore, there is a need for a solution for routing the movable nodes in an efficient way.Summary

[0015] It is an object of the invention to address at least some of the problems and issues outlined above. It is possible to achieve these objects and others by using methods, and systems as defined in the independent claims. It is an object of embodiments of the invention to update routing status of a network efficiently. It is also an object of embodiments of the invention to save network resources. It is possible to achieve one or more of these objects and possibly others by using methods and one or more network entities as defined in the attached independent claims.

[0016] According to one aspect, a method performed by a routing system is provided. The routing system comprises a communication network of a movable node, at least one mesh node and a border node. The movable node, the at least one mesh node and the border node communicatively connected with each other. Each mesh node and border node having a respective memory. The method comprises: sending, by a movable node, a post message to a parent node, wherein the post message comprises timing information about frequency hopping of the movable node, the parent node being a mesh node or a border node.

[0017] When the parent node is a mesh node, the method further comprises storing, in the mesh node, timing information related to the movable node in the memory of the mesh node, wherein the timing information related to the movable node comprising the timing information about frequency hopping of the movable node and a timestamp when the post message being received at the mesh node, wherein the stored timing information related to the movable node being deleted from the memory of the mesh node when the memory is full. The method further comprises forwarding, through the mesh node, the post message towards the border node and storing, in the border node, routing information related to the route between the movable node and the mesh node in the memory of the border node.

[0018] When the parent node is a border node, the method further comprises: storing, in the border node, the timing information related to the movable node and routing information relating to the route between the movable node and the border node in the memory of the border node, wherein the timing information related to the movable node comprising the timing information about frequency hopping of the movable node and a timestamp when the post message being received at the border node, wherein the stored timing information related to the movable node and routing information related to the route between the movable node and the border node being deleted from the memory of the border node when the memory is full.

[0019] According to another aspect, a method performed by a mesh node of a routing system is provided. The routing system comprising a communication network of a movable node, at least the mesh node and a border node. The movable node, the mesh node and the border node are communicatively connected with each other, the mesh node having a memory. The method comprises: receiving a post message from the movable node, wherein the post message comprises timing information about frequency hopping of the movable node; storing the timing information related to the movable node in the memory of the mesh node, wherein the timing information related to the movable node comprising the timing information about frequency hopping of the movable node and a timestamp when the post message being received at the mesh node, wherein the stored timing information related to the movable node being deleted from the memory of the mesh node when the memory is full. The method further comprises forwarding the post message towards the border node.

[0020] According to another aspect, a method performed by a border node of a routing system is provided. The routing system comprises a communication network of a movable node, at least one mesh node and a border node. The movable node, the at least one mesh node and the border node are communicatively connected with each other, the border node has a memory. The method comprises: receiving a post message originated from the movable node,wherein the post message comprises timing information about frequency hopping of the movable node.

[0021] When the post message is received via the at least one mesh node, the method further comprises storing routing information related to the route between the movable node and the parent node of the movable node in the memory of the border node, wherein the stored routing information related to the route between the movable node and the parent node of the movable node being deleted from the memory of the border node when the memory is full.

[0022] When the post message is received directly from the movable node, the method further comprises storing timing information related to the movable node and routing information relating to the route between the movable node and the border node in the memory of the border node, wherein the timing information related to the movable node comprising the timing information about frequency hopping of the movable node and a timestamp when the post message being received at the border node, wherein the stored timing information related to the movable node and routing information related to the route between the movable node and the border node being deleted from the memory of the border node when the memory is full.

[0023] According to another aspect, a routing system is provided. The routing system comprises a communication network of a movable node, at least one mesh node and a border node. The movable node, the at least one mesh node and the border node are communicatively connected with each other. Each of the movable node, the at least one mesh node and the border node comprises a processing circuitry and a memory respectively. The memory contains instructions executable by the processing circuitry, whereby the routing system is operative for performing the methods above.

[0024] According to another aspect, a mesh node of a routing system is provided. The routing system comprises a communication network of a movable node, the mesh node and a border node. The movable node, the mesh node and the border node are communicatively connected with each other. Each of themovable node, the mesh node and the border node comprise a processing circuitry and a memory respectively. The memory contains instructions executable by the processing circuitry, whereby the mesh node is operative for performing the methods above.

[0025] According to another aspect, a border node of a routing system is provided. The routing system comprises a communication network of a movable node, at least one mesh node and a border node. The movable node, the mesh node and the border node are communicatively connected with each other. Each of the movable node, the mesh node and the border node comprise a processing circuitry and a memory respectively. The memory contains instructions executable by the processing circuitry, whereby the border node is operative for performing the methods above.

[0026] With above aspects, when the amount of the movable nodes is large and the movable nodes keep moving, since the memories are deleted / cleared in time, the solution can effectively update the routing states and does not need to occupy too many resources for a long time.

[0027] Further possible features and benefits of this solution will become apparent from the detailed description below.Brief Description of Drawings

[0028] The solution will now be described in more detail by means of exemplary embodiments and with reference to the accompanying drawings, in which:

[0029] Fig. 1a-1c are schematic block diagrams of movable node, mesh node and border node in prior art.

[0030] Fig. 2 is an interaction diagram of the movable node, mesh node and border node in the prior art.

[0031] Fig. 3 is a flow chart illustrating a method performed by a routing system, according to possible embodiments.

[0032] Fig. 4a and 4b are schematic block diagrams of routing system, according to possible embodiments.

[0033] Fig. 5a and 5b are interaction diagrams of the routing system, according to possible embodiments.

[0034] Fig. 6 is a schematic block diagram of parent field in the post message, according to possible embodiments.

[0035] Fig. 7 is a flow chart illustrating a method performed by a mesh node, according to possible embodiments.

[0036] Fig. 8 is a flow chart illustrating a method performed by a border node, according to possible embodiments.

[0037] Fig. 9 is a block diagram illustrating the mesh node in more detail, according to further possible embodiments.

[0038] Fig. 10 is a block diagram illustrating the border node in more detail, according to further possible embodiments.Detailed Description

[0039] The invention is used in any communication network, e.g., a network which uses RPL. The nodes in the network may be any type of devices capable of communicating with other nodes. For example, the nodes may be machine type user equipment (UE) or a UE capable of machine to machine (M2M) communication, a sensor, a tablet, a mobile terminal, a smart phone, a laptop embedded equipped (LEE), a laptop mounted equipment (LME), a USB dongle, a Customer Premises Equipment (CPE), a wireless tag, etc.

[0040] As discussed in the Background, the nodes in the network are divided into three types. The nodes are divided by their position and function in the network, not by the device type.

[0041] Fig. 3, in combination with figs. 4a, 4b, 9 and 10, show a method performed by a routing system. The routing system 200 comprises acommunication network of a movable node 202, at least one mesh node 204 and a border node 208. The movable node 202, the at least one mesh node 204 and the border node 208 are communicatively connected with each other. Each mesh node 204 and border node 208 having a respective memory 1006, 1106. The method comprises: sending 310, by a movable node 202, a post message to a parent node, wherein the post message comprises timing information about frequency hopping of the movable node 202, the parent node being a mesh node 204 or a border node 208.

[0042] When the parent node is a mesh node 204, the method further comprises storing 312, in the mesh node 204, timing information related to the movable node 202 in the memory 1006 of the mesh node 204, wherein the timing information related to the movable node 202 comprises the timing information about frequency hopping of the movable node 202 and a timestamp indicating the time when the post message is received at the mesh node 204, wherein the stored 312 timing information related to the movable node 202 being deleted from the memory 1006 of the mesh node 204 when the memory 1006 is full. The method further comprises forwarding 314, through the mesh node 204, the post message towards the border node 208 and storing 316, in the border node 208, routing information related to the route between the movable node 202 and the mesh node 204 in the memory 1106 of the border node 208, wherein the stored 316 routing information related to the route between the movable node 202 and the mesh node 204 being deleted from the memory 1106 of the border node 208 when the memory 1106 is full.

[0043] When the parent node is a border node 208, the method further comprises: storing 322, in the border node 208, the timing information related to the movable node 202 and routing information relating to the route between the movable node 202 and the border node 208 in the memory 1106 of the border node 208, wherein the timing information related to the movable node 202 comprises the timing information about frequency hopping of the movable node 202 and a timestamp indicating the time when the post message is received at the border node 208, wherein the stored 322 timing information related to the movablenode 202 and routing information related to the route between the movable node 202 and the border node 208 being deleted from the memory 1106 of the border node 208 when the memory 1106 is full.

[0044] Fig. 4a and 4b, in conjunction with fig. 9 and fig. 10, show a routing system 200. The routing system 200 comprises a communication network which includes a movable node 202, at least one mesh node 204 and a border node 208. The nodes in the communication network can communicate with each other and the communication network can use RPL or another network protocol.

[0045] The mesh node 204 includes a memory 1006 and the border node 208 includes a memory 1106. In the sending step 310, the movable node 202 directly sends a post message to its parent node. The probe / registration step in the prior art is omitted. In the post message, timing information of FH of the movable node 202 is contained. The parent node can be a mesh node 204, as shown in fig. 4a, or a border node 208, as shown in fig. 4b. As discussed in the Background, the timing information about frequency hopping of the movable node 202 can be a timestamp which indicating the time when the movable node 202 started its frequency hopping sequence.

[0046] When the parent node is the mesh node 204, as shown in fig. 4a, upon the parent node 204 receiving the post message, timing information related to the movable node 202 is stored in the memory 1006 of the parent node 204 in the step 312. The timing information related to the movable node 202 includes the timing information about FH of the movable node 202. The timing information of FH is contained in the received post message. The timing information related to the movable node 202 also includes a timestamp, the timestamp indicating the time when the mesh node 204 received the post message from the movable node 202.

[0047] When storing 312 the timing information related to the movable node 202 in the memory 1006 of the mesh node 204, the memory 1006 is configured to operate in a ’’cache” manner, that is, the stored timing information related to the movable node 202 is deleted within a short time period, i.e. , when the memory1006 is full. For example, it may take 5-30 seconds before the memory 1006 is full, so that the stored timing information in the memory 1006 is deleted after 5-30 seconds since being stored. To be specific, it may be deleted after 10 seconds since being stored. Since the information stored in the memory 1006 is deleted quite frequently, the memory 1006 does not need to be very large, and the memory 1006 will not be occupied by the stored information for a long time. Therefore, the efficiency of the whole network increases.

[0048] In the step 314, after the mesh node 204 has stored the timing information related to the movable node 202 in its memory 1006, the mesh node 204 forwards the post message towards the border node 208. The post message may reach the border node 208 directly from the mesh node 204, or via any other intermediate mesh node, e.g., 206.

[0049] In the step 316, when the border node 208 receives the post message, it stores routing information in its memory 1106. The routing information relates to the route between the movable node 202 and the parent node, that is the mesh node 204. Similar as the step 312, the stored information in the memory 1106 is deleted when the memory 1106 is full, e.g., the stored information in the memory 1106 is deleted after 5-30 seconds since being stored, specifically after 10 seconds since being stored.

[0050] When the parent node is a border node 208, as shown in fig. 4b, upon the parent node 208 receiving the post message, timing information related to the movable node 202 is stored in the memory 1106 of the border node 208 in the step 322. Similar as above, the timing information related to the movable node 202 includes the timing information about FH of the movable node 202. The timing information of FH is contained in the received post message. The timing information related to the movable node 202 also includes a timestamp, the timestamp indicating the time when the border node 208 received the post message from the movable node 202.

[0051] Besides storing the timing information related to the movable node 202, routing information is also stored in the memory 1106 of the border node 208 inthe step 322. The routing information relates to the route between the movable node 202 and the border node 208. Similar as the step 312, the stored timing information and routing information in the memory 1106 is deleted when the memory 1106 is full, e.g., the stored information in the memory 1106 is deleted after 5-30 seconds since being stored, specifically after 10 seconds since being stored.

[0052] Generally speaking, there are two kinds of information which are stored. The first kind of information is the timing information related to the movable node 202. The timing information related to the movable node 202 includes the timing information about FH of the movable node 202 and the timestamp indicating the time when the post message is received by the parent node of the movable node 202. This timing information related to the movable node 202 is always stored in the memory of the parent node of the movable node 202. Therefore, when the parent node is the mesh node 204, the timing information related to the movable node 202 is stored in the memory of the mesh node 204. When the parent node is the border node 208, the timing information related to the movable node 202 is stored in the memory of the border node 208.

[0053] The second kind of information is the routing information relating to the route between the movable node 202 and its parent node. No matter which node is the parent node, the routing information relating to the route between the movable node 202 and its parent node is always stored in the memory of the border node 208.

[0054] Both the memories of the mesh node 204 and the border node 208 work in a “cache” manner, that is, the memory 1006 of the mesh node 204 and the memory 1106 of the border node 208 deletes the stored information when the memory is full. The size of the memory is limited, so the deletion can be performed after a short time period, e.g., 5-30 seconds, specifically 10 seconds.

[0055] Therefore, when the parent node is the mesh node 204, the mesh node 204 stores the timing information related to the movable node 202 in its memory 1006, and the border node 208 stores the routing information in its memory.When the parent node is the border node 208, the border node 208 stores both the timing information related to the movable node 202 and the routing information in its memory. Both memories delete the stored information when the respective memory is full.

[0056] By this method, firstly the probe and registration steps are omitted. The storage of timing information and routing information is performed when posting the post message. Therefore, the amount of the messages sent in the whole network is reduced, and the burden of the whole network is also reduced. Secondly, since the stored timing information and the routing information are deleted when the memories are full, the stored information is deleted / refreshed after a short while, and no information will occupy the memories for a long time. Thus, the mesh node 204 and border node 208 can keep information of more movable nodes. That is to say, the scale of the network can be significantly expanded, the network resource can be saved and the network efficiency is improved.

[0057] Fig. 5a shows an interaction diagram when the parent node of the movable node 202 is the mesh node 204. In step 5.1 , the movable node 202 sends a post message to the parent node 204. The parent node 204 stores timing information related to the movable node in its memory in step 5.2. The stored timing information is deleted when the memory is full. In step 5.3, the mesh node 204 forwards the post message towards the border node 208. The border node 208 stores the routing information in its memory in step 5.4. The stored information is deleted when the memory is full.

[0058] Fig. 5b shows an interaction diagram when the parent node of the movable node 202 is the border node 208. In step 5.1 , the movable node 202 sends a post message to the border node 208. In step 5.2, the border node 208 stores both timing information and routing information related to the movable node 202 in its memory. The stored information is deleted when the memory is full

[0059] According to other embodiments, referring to fig. 3, the method further comprises: replying 318, 328, by the border node 208, a reply message to the movable node 202, through a route based on the routing information stored 316, 322 in the memory 1106 of the border node 208. Referring to figs. 5a and 5b, the reply message is sent to the movable node 202 in step 5.5 in the fig. 5a or in step 5.3 in the fig. 5b.

[0060] By this method, the movable node 202 is replied by the border node 208, via the route which the post message has passed through.

[0061] According to other embodiments, the post message comprises a parent field, in which the parent node information of the movable node 202 is stored.

[0062] Referring to fig. 6, a parent field is added to the post message. The parent field includes 5 bytes. In the parent field, the movable node 202 fills in the parent node information. Therefore, the nodes in the route get to know the parent information of the movable node 202 upon receiving the post message.

[0063] According to other embodiments, according to fig. 7, a method performed by a mesh node 204 of a routing system 200 is provided. The routing system comprises a communication network of a movable node 202, at least the mesh node 204 and a border node 208. The movable node 202, the mesh node 204 and the border node 208 are communicatively connected with each other. The mesh node 204 has a memory 1006, and the method comprises: receiving 412 a post message from the movable node 202, wherein the post message comprises timing information about frequency hopping of the movable node 202. The method further comprises storing 414 the timing information related to the movable node 202 in the memory 1006 of the mesh node 204, wherein the timing information related to the movable node 202 comprising the timing information about frequency hopping of the movable node 202 and a timestamp when the post message is received at the mesh node 204, wherein the stored 414 timing information related to the movable node 202 being deleted from the memory 1006 of the mesh node 204 when the memory 1006 is full. The method further comprises forwarding 416 the post message towards the border node 208.

[0064] According to other embodiments, the post message comprises a parent field, in which the parent node information of the movable node 202 is included.

[0065] According to other embodiments, referring to fig. 8, a method performed by a border node 208 of a routing system 200 is provided. The routing system 200 comprises a communication network of a movable node 202, at least one mesh node 204 and a border node 208. The movable node 202, the at least one mesh node 204 and the border node 208 are communicatively connected with each other, the border node 208 has a memory 1106. The method comprises: receiving 510 a post message originated from the movable node 202, wherein the post message comprises timing information about frequency hopping of the movable node 202.

[0066] When the post message is received 510 via the at least one mesh node 204, the method further comprises storing 512 routing information related to the route between the movable node 202 and the parent node of the movable node 202 in the memory 1106 of the border node 208. The stored 512 routing information is deleted from the memory 1106 when the memory is full.

[0067] When the post message is received 510 directly from the movable node 202, the method further comprises storing 522 timing information related to the movable node 202 and routing information relating to the route between the movable node 202 and the border node 208 in the memory 1106 of the border node 208, wherein the timing information related to the movable node 202 comprising the timing information about frequency hopping of the movable node 202 and a timestamp indicating the time when the post message is received at the border node 208. The stored 522 timing information and routing information is deleted from the memory 1106 when the memory 1106 is full.

[0068] According to other embodiments, referring to fig. 8, the method further comprises replying 518, 528 a reply message to the movable node 202, through a route based on the routing information stored 512, 522 in the memory 1106 of the border node 208.

[0069] According to other embodiments, the post message comprises a parent field, in which the parent node information of the movable node 202 is included.

[0070] According to other embodiments, referring to fig. 9 and 10, a routing system 200 is provided. The routing system 200 comprises a communication network of a movable node 202, at least one mesh node 204 and a border node 208. The movable node 202, the at least one mesh node 204 and the border node 208 are communicatively connected with each other. Each of the movable node 202, the at least one mesh node 204 and the border node 208 comprises a processing circuitry 1003, 1103 and a memory 1006, 1106 respectively. The memory 1006, 1106 contains instructions 1005, 1105 executable by the processing circuitry 1003, 1103, whereby the routing system is operative for performing the methods discussed in the embodiments above.

[0071] According to other embodiments, a mesh node 204 of a routing system 200 is provided. The routing system 200 comprises a communication network of a movable node 202, the mesh node 204 and a border node 208. The movable node 202, the mesh node 204 and the border node 208 are communicatively connected with each other. Each of the movable node 202, the mesh node 204 and the border node 208 comprising a processing circuitry 1003, 1103 and a memory 1006, 1106 respectively. The memory 1006, 1106 contains instructions 1005, 1105 executable by the processing circuitry 1003, 1103, whereby the mesh node 204 is operative for performing the methods discussed in the embodiments above.

[0072] According to other embodiments, a border node 208 of a routing system 200 is provided. The routing system 200 comprises a communication network of a movable node 202, at least one mesh node 204 and a border node 208. The movable node 202, the mesh node 204 and the border node 208 are communicatively connected with each other. Each of the movable node 202, the mesh node 204 and the border node 208 comprises a processing circuitry 1003, 1103 and a memory 1006, 1106 respectively. The memory 1006, 1106 contains instructions 1005, 1105 executable by the processing circuitry 1003, 1103, whereby the border node 208 is operative for performing the methods discussed in the embodiments above.

[0073] According to other embodiments, referring to fig. 9, the mesh node 204 may further comprise a communication unit 1002, which may be considered to comprise conventional means for communication with other devices, such as a transceiver for transmission and reception of signals. The instructions 1005 executable by said processing circuitry 1003 may be arranged as a computer program stored e.g. in said memory 1006. The processing circuitry 1003 and the memory 1006 may be arranged in a sub-arrangement 1001. The sub-arrangement 1001 may be a micro-processor and adequate software and storage therefore, a Programmable Logic Device, PLD, or other electronic component(s) / processing circuit(s) configured to perform the methods mentioned above. The processing circuitry 1003 may comprise one or more programmable processors, applicationspecific integrated circuits, field programmable gate arrays or combinations of these adapted to execute instructions.

[0074] The instructions / computer program 1005 may be arranged such that when its instructions are run in the processing circuitry, they cause the mesh node 204 to perform the steps described in any of the described embodiments of the mesh node 204 and the method performed by the mesh node 204. The instructions / computer program 1005 may be carried by a computer program product connectable to the processing circuitry 1003. The computer program product may be the memory 1006, or at least arranged in the memory. The memory 1006 may be realized as for example a RAM (Random-access memory), ROM (Read-Only Memory) or an EEPROM (Electrical Erasable Programmable ROM). In some embodiments, a carrier may contain the instructions / computer program 1005. The carrier may be one of an electronic signal, an optical signal, an electromagnetic signal, a magnetic signal, an electric signal, a radio signal, a microwave signal, or computer readable storage medium. The computer-readable storage medium may be e.g. a CD, DVD or flash memory, from which the program could be downloaded into the memory 1006. Alternatively, the computer program may be stored on a server or any other entity to which the mesh node 204 has access via the communication unit 1002. The instructions / computer program 1005 may then be downloaded from the server into the memory 1006.

[0075] According to other embodiments, referring to fig. 10, the border node 208 may further comprise a communication unit 1102, which may be considered to comprise conventional means for communication with other devices, such as a transceiver for transmission and reception of signals. The instructions 1105 executable by said processing circuitry 1103 may be arranged as a computer program stored e.g. in said memory 1106. The processing circuitry 1103 and the memory 1106 may be arranged in a sub-arrangement 1101. The sub-arrangement 1101 may be a micro-processor and adequate software and storage therefore, a Programmable Logic Device, PLD, or other electronic component(s) / processing circuit(s) configured to perform the methods mentioned above. The processing circuitry 1103 may comprise one or more programmable processor, applicationspecific integrated circuits, field programmable gate arrays or combinations of these adapted to execute instructions.

[0076] The instructions / computer program 1105 may be arranged such that when its instructions are run in the processing circuitry, they cause border node 208 to perform the steps described in any of the described embodiments of the border node 208 and the method performed by the border node 208. The instructions / computer program 1105 may be carried by a computer program product connectable to the processing circuitry 1103. The computer program product may be the memory 1106, or at least arranged in the memory. The memory 1106 may be realized as for example a RAM (Random-access memory), ROM (Read-Only Memory) or an EEPROM (Electrical Erasable Programmable ROM). In some embodiments, a carrier may contain the computer program 1105. The carrier may be one of an electronic signal, an optical signal, an electromagnetic signal, a magnetic signal, an electric signal, a radio signal, a microwave signal, or computer readable storage medium. The computer-readable storage medium may be e.g. a CD, DVD or flash memory, from which the program could be downloaded into the memory 1106. Alternatively, the computer program may be stored on a server or any other entity to which the border node 208 has access via the communication unit 1102. The computer program 1105 may then be downloaded from the server into the memory 1106.

[0077] Although the description above contains a plurality of specificities, these should not be construed as limiting the scope of the concept described herein but as merely providing illustrations of some exemplifying embodiments of the described concept. It will be appreciated that the scope of the presently described concept fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the presently described concept is accordingly not to be limited. Reference to an element in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more." Further, the term “a number of”, such as in “a number of wireless devices” signifies one or more devices. All structural and functional equivalents to the elements of the above-described embodiments that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed hereby. Moreover, it is not necessary for an apparatus or method to address each and every problem sought to be solved by the presently described concept, for it to be encompassed hereby. In the exemplary figures, a broken line generally signifies that the feature within the broken line is optional.

Claims

CLAIMS1 . A method performed by a routing system (200), the routing system(200) comprising a communication network of a movable node (202), at least one mesh node (204) and a border node (208), the movable node (202), the at least one mesh node (204) and the border node (208) being communicatively connected with each other, each mesh node (204) and border node (208) comprising a respective memory (1006, 1106), the method comprises:- sending (310), by the movable node (202), a post message to a parent node, wherein the post message comprises timing information about frequency hopping of the movable node (202), the parent node being a mesh node (204) or a border node (208); when the parent node is a mesh node (204),- storing (312), in the mesh node (204), timing information related to the movable node (202) in the memory (1006) of the mesh node (204), wherein the timing information related to the movable node (202) comprises the timing information about frequency hopping of the movable node (202) and a timestamp indicating the time when the post message is received at the mesh node (204), and wherein the stored (312) timing information related to the movable node (202) being deleted from the memory (1006) of the mesh node (204) when the memory (1006) is full,- forwarding (314), through the mesh node (204), the post message towards the border node (208);- storing (316), in the border node (208), routing information related to the route between the movable node (202) and the mesh node (204) in the memory (1106) of the border node (208), wherein the stored (316) routing information related to the route between the movable node (202) and the mesh node (204) being deleted from the memory (1106) of the border node (208) when the memory (1106) is full; when the parent node is a border node (208),- storing (322), in the border node (208), timing information related to the movable node (202) and routing information related to the route between the movable node (202) and the border node (208) in the memory (1106) of the border node (208), wherein the timing information related to the movable node (202) comprises the timing information about frequency hopping of the movable node (202) and a timestamp indicating the time when the post message is received at the border node (208), wherein the stored (322) timing information related to the movable node (202) and routing information related to the route between the movable node (202) and the border node (208) being deleted from the memory(1106) of the border node (208) when the memory (1106) is full.

2. The method as claimed in claim 1 , wherein the method further comprises:- replying (318, 328), by the border node (208), a reply message to the movable node (202), through a route based on the routing information stored (316, 322) in the memory (1106) of the border node (208).

3. The method as claimed in claim 1 or 2, wherein the post message comprises a parent field, in which the parent node information of the movable node (202) is stored.

4. A method performed by a mesh node (204) of a routing system (200), the routing system comprising a communication network of a movable node (202), at least the mesh node (204) and a border node (208), the movable node (202), the mesh node (204) and the border node (208) being communicatively connected with each other, the mesh node (204) comprising a memory (1006), the method comprises:- receiving (412) a post message from the movable node (202), wherein the post message comprises timing information about frequency hopping of the movable node (202);- storing (414) timing information related to the movable node (202) in the memory (1006) of the mesh node (204), wherein the timing information related to the movable node (202) comprises the timing information about frequency hopping of the movable node (202) and a timestamp indicating the time when the post message is received at the mesh node (204), wherein the stored (414) timing information related to the movable node (202) being deleted from the memory (1006) of the mesh node (204) when the memory (1006) is full;- forwarding (416) the post message towards the border node (208).

5. The method as claimed in claim 4, wherein the post message comprises a parent field, in which the parent node information of the movable node 202 is included.

6. A method performed by a border node (208) of a routing system (200), the routing system (200) comprising a communication network of a movable node (202), at least one mesh node (204) and a border node (208), the movable node (202), the at least one mesh node (204) and the border node (208) being communicatively connected with each other, the border node (208) comprising a memory (1106), the method comprises:- receiving (510) a post message originated from the movable node (202), wherein the post message comprises timing information about frequency hopping of the movable node (202); when the post message is received (510) via the at least one mesh node (204),- storing (512) routing information related to the route between the movable node (202) and the parent node of the movable node (202) in the memory (1106) of the border node (208), wherein the stored (512) routing information related to the route between the movable node (202) and the parent node of the movable node (202) being deleted from the memory (1106) of the border node (208) when the memory (1106) is full;when the post message is received (510) directly from the movable node (202),- storing (522) timing information related to the movable node (202) and routing information related to the route between the movable node (202) and the border node (208) in the memory (1106) of the border node (208), wherein the timing information related to the movable node (202) comprises the timing information about frequency hopping of the movable node (202) and a timestamp indicating the time when the post message is received at the border node (208), wherein the stored (522) timing information related to the movable node (202) and routing information related to the route between the movable node (202) and the border node (208) being deleted from the memory (1106) of the border node (208) when the memory (1106) is full.

7. The method as claimed in the claim 6, wherein the method further comprises:- replying (518, 528) a reply message to the movable node (202), through a route based on the routing information stored (512, 522) in the memory (1106) of the border node (208).

8. The method as claimed in claim 6 or 7, wherein the post message comprises a parent field, in which the parent node information of the movable node (202) is included.

9. A routing system (200) comprising a communication network of a movable node (202), at least one mesh node (204) and a border node (208), the movable node (202), the at least one mesh node (204) and the border node (208) being communicatively connected with each other, each of the movable node (202), the at least one mesh node (204) and the border node (208) comprising a processing circuitry (1003, 1103) and a memory (1006, 1106) respectively, the memory (1006, 1106) containing instructions (1005, 1105) executable by theprocessing circuitry (1003, 1103), whereby the routing system is operative for performing the method as claimed in any one of claims 1-3.

10. A mesh node (204) of a routing system (200), the routing system (200) comprising a communication network of a movable node (202), the mesh node (204) and a border node (208), the movable node (202), the mesh node (204) and the border node (208) being communicatively connected with each other, each of the movable node (202), the mesh node (204) and the border node (208) comprising a processing circuitry (1003, 1103) and a memory (1006, 1106) respectively, the memory (1006, 1106) containing instructions (1005, 1105) executable by the processing circuitry (1003, 1103), whereby the mesh node (204) is operative for performing the method as claimed in any one of claims 4-5.

11. A border node (208) of a routing system (200), the routing system (200) comprising a communication network of a movable node (202), at least one mesh node (204) and a border node (208), the movable node (202), the mesh node (204) and the border node (208) being communicatively connected with each other, each of the movable node (202), the mesh node (204) and the border node (208) comprising a processing circuitry (1003, 1103) and a memory (1006, 1106) respectively, the memory (1006, 1106) containing instructions (1005, 1105) executable by the processing circuitry (1003, 1103), whereby the border node (208) is operative for performing the method as claimed in any one of claims 6-8.

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