KR20070097245A - Routing method for wireless network and system thereof - Google Patents

Abstract

A routing method in a wireless network and a system thereof are provided to minimize the overall energy consumption and shorten routing and recovery time by reducing the amount of transmitted packets for routing and overheads for each node in a WPAN(Wireless Personal Area Network). A node, receiving an RREQ(Routing Request) packet, checks whether the RREQ packet has been repeatedly received through the flooding of another node(S500,S510). If not, the node confirms whether it is a cluster head(S520). If so, the node confirms whether it is a destination node(S530). If so, the node transmits an RREP(Routing Response) packet to the previous node(S540). In case the node is not the destination node, however, the node adds its own address to the header of the received RREQ packet and floods the RREQ packet(S550).

Description

ROUTING METHOD FOR WIRELESS NETWORK AND SYSTEM THEREOF

1 is a conceptual diagram of an AODV scheme for a PAN according to the prior art.

2 is a conceptual diagram of a DSR scheme for a PAN according to the prior art.

3 is a conceptual diagram of a CGSR scheme for a PAN according to the prior art.

4 is a block diagram of a wireless personal area network system according to a preferred embodiment of the present invention.

5 is a flowchart specifically illustrating a sequential operation of a path setting method according to an exemplary embodiment of the present invention.

FIG. 6 is a flowchart specifically illustrating a sequential operation of step 560 in the path setting method of FIG. 5. FIG.

The present invention relates to a routing method in a wireless network, and more particularly, to an efficient routing method in a wireless personal area network using a communication protocol such as ZigBee and a system therefor.

Personal Area Network (PAN), which is called personal area network, is a concept in contrast to the well-known local area network (LAN) or wide area network (WAN). Each device owned by an individual is used for the convenience of the person. It refers to configuring a network of.

In an effort to implement such a PAN wirelessly, the IEEE 802.15 Working Group has set up a wireless personal area network (WPAN) as a standard for short-range wireless networks, and has four task groups (TGs) under it. Among the four TGs, IEEE 802.15.1 is Bluetooth, IEEE 802.15.3 and IEEE 802.15.3a are high-speed WPAN, and IEEE 802.15.4, also known as ZigBee, is low speed of 250 kbps or less. (low rate) Standard for WPAN.

The Zigbee standardizes the upper protocol and application layer based on the physical layer / media access control layer standardized by the IEEE802.15.4 committee, and is a representative technology of the wireless sensor network.

The Zigbee is applied to a wireless measurement and alarm system that notifies a manager's wireless alarm of the values and data measured by various sensors installed at a factory site or an industrial site. In this case, the wireless metrology and alarm system adopts a tree routing fixed routing scheme in consideration of reliability and ease of implementation. However, since the path setting must be changed at any time in an environment in which the wireless alarm carried by the administrator moves, the fixed path setting method of the tree structure described above is not suitable. On the other hand, if a failure or failure of a router or device node occurs, new path information has to be obtained. Thus, the above-described fixed routing method of the tree structure is not suitable for the wireless measurement and alarm system.

On the other hand, in general, the radio measurement / alarm system using the Zigbee is a tree structure of the master (slave) mode, or a mesh or a peer-to-peer structure It also forms a wireless network. In this case, even if all routers or device nodes move, there is no need to perform routing and only the mobility of the wireless alarm owned by the administrator is guaranteed. Therefore, the existing ad hoc type that requires a lot of rerouting process is required. Unlike the network, the change of network type does not occur frequently.

In addition, the Zigbee standard specification basically provides an ad hoc on-demand distance vector (AODV) method, which is a routing table and packet flooding. Using the technique, information management and path acquisition of the route are performed.

However, in this process, a routing message (RREQ) requesting a route establishment request and a routing reply (RREP) packet responding according to the route establishment request are requested, and a hello message is requested to update the route information during the table termination time. Therefore, there was a problem that the overhead is increased.

1 is a flowchart illustrating a path setting method according to an AODV method.

The path search and acquisition step (step 100) is performed by performing a reverse path by performing a path search using an RREQ packet and transmitting an RREP packet when the RREQ packet arrives at a destination node. The route acquisition procedure consists of a duplicate check, a route table check, a destination check, and a route validity check.

The route table management step (step 102) manages the route table by setting an expiration time in order to maintain the latest information of the route table and reduce the overhead generated. Here, the end time is generally set to 10 [ms].

The path connection management step (step 104) periodically transmits a hello message to determine whether the path connection is valid, and requests a response message from the node to which the path is connected.

If no response message is received (step 105), the path maintenance step (step 106) sends a routing error (RRE) packet to the previous node to report the path, to report the path error, and again to obtain the path. Return to the path search and acquisition step (step 100).

On the other hand, another method based on demand is a dynamic source routing (DSR) method. This uses a route cache without a route table based on packet flooding. FIG. 2 sequentially illustrates a procedure of a route establishment method according to a DSR scheme.

First, a specific node adds its address to the RREQ packet header to flood the neighbor node for initial path establishment. If any node receives the flooded RREQ packet (step 200), it is checked whether it is the destination node of the RREQ packet (step 202). If it is not the destination node, it floods the RREQ packet.

If the node is the destination node, the node receiving the RREQ packet generates an RREP packet by adding the destination address to the address added to the packet header portion and transmits (unicasts) the source node (step 204).

Through this process, each node can have multipath and piggyback RREP packet to RREQ packet to support asymmetric link.

However, in the above-described path setting method, since the entire path is included in the RREQ packet header, resources are wasted, and the path acquisition time is delayed due to the movement of the node and errors in the path cache over time. Occurred.

Meanwhile, typical cluster-based routing methods in an Ed Hoc environment include Clusterhead Gateway Switch Routing (CGSR) and Zone Routing Protocol (ZRP).

3 is a conceptual diagram illustrating a CGSR scheme. Referring to FIG. 3, in the CGSR scheme, all nodes N1 to N5 wishing to transmit transmit data to the cluster heads CHA and CHB, and a gateway G1 between the cluster heads CHA and CHB. Relay to ~ G3). This CGSR scheme prevents inefficient packet flooding during the path establishment process by clustering each node. However, since CGSR path setting method uses table-driven method, there is a problem to always update and maintain the latest path information. Also, since each cluster head must manage all nodes in the cluster, There is a problem that an overload is applied. In addition, when wide coverage is desired, a gateway needs to be installed, resulting in an increase in installation cost.

In addition, location-based routing (LAR), a location-based method, uses a global positioning system (GPS) to transmit data only toward the destination node, thereby reducing the amount of packets generated for path acquisition. However, the application in a real environment has a lot of difficulties.

SUMMARY OF THE INVENTION The present invention is to overcome the above-mentioned conventional problems, and saves the overall energy consumption by reducing the amount of packets transmitted and the overhead for each node for the routing of the wireless personal area network. Another object of the present invention is to provide a route setting method and system according to the wireless personal area network which can shorten the recovery time.

In order to achieve the above object and to solve the problems of the prior art, the method for routing a wireless personal area network according to the present invention comprises clustering a plurality of nodes belonging to the wireless personal area network into one or more clusters. A clustering step of setting any node in the cluster as a cluster head; An AODV path setting step of performing path setting according to an ad hoc on-demand distance vector (AODV) method among nodes in the cluster; The cluster heads may include a DSR path setting step of performing path setting according to a dynamic source routing (DSR).

The present invention clusters a plurality of nodes, sets any one node in each cluster as a cluster head, and implements routing according to AODV routing between nodes in each cluster. The path setting is performed between the cluster heads according to the DSR path setting method.

The present invention does not require the cluster head to manage information on the nodes in the cluster, and by maintaining multiple paths to the cluster head, the overall overhead and path acquisition time are reduced, thereby moving the wireless instrumentation / information system. Efficient routing for overwork and failures

Prior to this description of the present invention, terms used in the present invention are defined as follows.

Flooding refers to a batch transmission of a packet received by a node back to arbitrary nodes. An RREQ packet is required for initial routing. The header of the RREQ packet includes a source address, an address of a transit node, Route information including a destination address and the like is included. The RREP packet is a response packet to the RREQ packet generated at the destination node, and the header of the RREP packet includes the route information including the destination address, the address of the transit node, the source address, and the like.

The present invention clusters adjacent nodes around the router in a wireless measurement / alarm system in which the wireless alarm that is a destination node moves while the router is fixed, and nodes within the cluster are routed according to the AODV method. The setting is implemented, and the path between the clusters is set by the DSR method.

For example, referring to FIG. 4 illustrating a schematic configuration of a wireless measurement / alarm system according to a preferred embodiment of the present invention, nodes constituting the wireless measurement / alarm system may include first to third clusters C1 ˜. C3) can be clustered.

The first cluster C1 may include nodes S1 and S2 as wireless measuring instruments, node A1 as a wireless alarm, and node CH1 serving as a cluster head as a router, and a second cluster C2. In the third cluster (C3) may be composed of a node (S3), which is a wireless meter, a node (A2), which is a wireless alarm, and a node (CH2), which is a cluster head, as a router. The node A3 may be configured as a node CH3 serving as a cluster head as a router.

When each node is its own cluster head, the path setting with the cluster head is performed according to the DSR, and the path setting with the nodes in the cluster is AODV according to the preferred embodiment of the present invention.

In addition, each node implements routing according to ADOV when it is not a cluster head. Therefore, each node includes its own address, cluster head configuration information, and route table, and receives the RREQ packet from another node to establish routing. Temporarily store the received RREQ packet until it completes.

A route setting method according to a preferred embodiment of the present invention applicable to the wireless measurement / alarm system described above will be described in detail with reference to the flowcharts of FIGS. 5 to 6.

Any node of FIG. 4 may receive an RREQ packet for path establishment (step 500). In this case, the RREQ packet may be an RREQ packet flooded by one node as a source for routing, or an RREQ packet re-flooded when the node receiving the RREQ packet is not the destination node. Here, the node receiving the RREQ packet receives the RREQ packet and temporarily stores it.

The node receiving the RREQ packet checks whether the RREQ packet is duplicated through flooding by another node (step 510).

If the RREQ packet is duplicated and already stored, the node removes the received RREQ packet (step 512).

If the RREQ packet is not duplicated, the node checks whether it is a cluster head (step 520).

If it is the cluster head, it is checked whether it is the destination node (step 530). If it is the destination node in step 530, the RREP packet, which is a response packet, is transmitted to the previous node (step 540). Otherwise, the RREQ packet is flooded after adding its address to the header of the received RREQ packet. The process ends (step 550).

If it is not the cluster head in step 520, it is checked whether the path on the received RREQ packet is on its path table and then transmits an RREQ packet or an RREP packet (step 560). Hereinafter, operation 560 will be described in detail with reference to FIG. 6.

 First, the node checks whether the route information carried in the received RREQ packet exists in its route table (step 600). Here, the path included in the RREQ packet may be for reverse path establishment according to the AODV method or cluster head addresses may be accumulated in the header of the packet according to the DSR method.

If the path included in the RREQ packet does not exist in its path table, the node floods the received RREQ packet according to the AODV (step 610) and ends.

If the path included in the RREQ packet exists in its own route table, it is checked whether it is the destination node (step 620). If it is the destination node in step 620, the node checks whether the path existing in its path table is valid using the path information on the RREQ packet (step 622). In this case, the validity of the route is determined as follows. First, a link cost value of a path included in the received RREQ packet is calculated, and the link cost value for the corresponding path of the path table is compared with the calculated link cost value. If the link cost value of the path included in the RREQ packet is smaller than the link cost value of the corresponding path in the path table, it is determined that the path is invalid. If the link cost value of the path included in the RREQ packet is larger than the link cost value for the corresponding path in the path table, it is determined that the corresponding path is valid. Here, although the preferred embodiment of the present invention exemplifies only determining the validity of the path based on the link cost value, it will be apparent to those skilled in the art by the present invention that various known techniques for determining the validity of the path may be employed.

If the route existing in the route table is valid, the node removes the received RREQ packet (step 624), and then transmits an RREP packet, which is a response packet to the received RREQ packet, to the previous node. 626).

If the route existing in the route table in step 622 is not valid, the node updates its route table according to the route contained in the received RREQ packet (step 623), and the node updates the received route table for the received RREQ packet. After the RREP packet, which is a response packet, is transmitted to the previous node (step 626), the process ends.

On the other hand, if it is not the destination node in step 610, it is checked whether the path of its own route table is valid using the path information on the RREQ packet (step 630). At this time, the method of determining whether the path of the path table is valid is the same as the method described above.

If the path of the route table is valid in step 630, the node removes the received RREQ packet (step 632), generates a new RREQ packet according to the path of its route table (step 634), and generates the new RREQ. The packet is flooded to other cluster heads and nodes belonging to its cluster (step 635).

If the route existing in the route table is not valid at step 630, the node updates its route table according to the route included in the received RREQ packet (step 638), and floods the received RREQ packet. (Step 639).

The process of setting a route according to the route setting method of the present invention described above will be briefly described.

First, a process in which one cluster head requests routing to another cluster head will be described.

First, a case in which the cluster head CH1 of the first cluster C1 requests a path setting with the cluster head CH2 of the second cluster C2 is as follows. The cluster head CH1 floods the RREQ packet. The cluster head CH2 receiving the RREQ packet flooded by the cluster head CH1 transmits an RREP packet, which is a response packet to the RREQ packet, to the cluster head CH1, thereby providing a path between the cluster heads CH1 and CH2. Is set.

In contrast, a case in which a node S1 in the first cluster C1 requests a route setting to a node A2 of the second cluster C2 will be described below. The node S1 floods the RREQ packet for routing to the node A2. The cluster head CH1 receiving the RREQ packet flooded by the node S1 inserts and floods information about its own path into the header of the RREQ packet, and the RREQ packet to which the path is added is the second cluster C2. Is received at the cluster head CH2. The cluster head CH2 inserts and floods information on its path back into the RREQ packet. The node A2 receiving the RREQ packet having the path information about the first and second cluster heads CH1 and CH2 inserted therein receives the RREP packet, which is a response packet to the RREQ packet, from the node of the first cluster C1 ( By transmitting to S1), a path between one node S1 in the first cluster C1 and one node A2 of the second cluster C2 is established.

Meanwhile, in FIG. 5, detailed description of the path maintenance step by the AODV method between nodes in the cluster is omitted, but nodes in each cluster periodically send a hello message according to the AODV method. Send a message to the user, and check whether the path is connected according to the response.

As described above, the present invention clusters a plurality of nodes, performs clustering in a cluster according to the AODV method, and clustering between clusters in accordance with a DSR method.

In this way, since only the cluster heads, that is, the cluster heads, perform the routing according to the DSR scheme, the entire node performs the routing according to the DSR scheme, thereby significantly reducing the amount of addresses inserted in the header of the RREQ packet. Can be.

In addition, since nodes in the cluster implement the path setting according to the AODV method, it is possible to significantly reduce the amount of hello message transmission for maintaining the path, as compared with the entire node performing the path setting according to the AODV method.

In addition, since the nodes in the cluster implement their own routing according to the AODV method, the cluster head does not have to manage all the nodes in the cluster, thereby reducing the overhead of the cluster head compared to the conventional cluster-based routing method. Can be.

As described above, the present invention can reduce the overall energy consumption and shorten the path setting and recovery time by reducing the data amount of the RREQ packet, the transmission amount of the hello message, and the overhead compared to the conventional path setting technology.

In addition, since the path setting between the cluster heads is made by the DSR method, the path recovery time can be shortened due to the multi path in the case of a node failure or failure.

Embodiments of the present invention described above include a computer readable medium including program instructions for performing various computer-implemented operations. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions on the media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those having skill in the computer software arts.

As described above, the present invention reduces the amount and overhead of packets for routing a wireless personal area network, thereby saving overall energy consumption and reducing the routing and recovery time.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above-described embodiments, which can be variously modified and modified by those skilled in the art to which the present invention pertains. Modifications are possible.

Accordingly, the spirit of the present invention should be understood only by the claims set forth below, and all equivalent or equivalent modifications thereof will belong to the scope of the present invention.

Claims (6)

In the routing method in a wireless network consisting of a plurality of nodes, Clustering the nodes into at least one cluster and setting any one node within each cluster as a cluster head; An AODV path setting step of performing path setting according to an ad hoc on-demand distance vector (AODV) method among nodes in the cluster; DSR routing step for performing path establishment between the cluster heads according to a dynamic source routing (DSR). Route setting method in a wireless network comprising a. In at least one cluster consisting of a plurality of nodes, each cluster is a routing method in a wireless network having a cluster head, (a) receiving a flooded RREQ Packet from a specific node; (b) the node checking whether it is a cluster head and whether it is a destination node of an RREQ packet; (c) if it is a cluster head and a destination node of the RREQ packet, sending a RREP Packet to a previous node; And (d) if it is a cluster head and is not a destination node of the RREQ packet, flooding the RREQ packet after adding its address to the header of the received RREQ packet. Path setting method in a wireless network comprising a. The method of claim 2, wherein the path setting method (e) if the node is not a cluster head and is a destination node, checking whether the route on its route table is valid by comparing the route on the received RREQ packet with the corresponding route on its route table; (f) In step (e), if the route on its route table is valid, the received RREQ packet is removed; if the route on its route table is invalid, the route on its route table is deleted. Updating with a path on a packet; And (g) transmitting a RREP Packet to the previous node for the RREQ packet Path setting method in a wireless network comprising a. The method of claim 2, wherein the path setting method (h) if the node is neither a cluster head nor a destination node, comparing the route on the received RREQ packet with the corresponding route in its route table to determine whether the route in its route table is valid; (i) in step (h), if the route on its route table is valid, removing the received RREQ packet and generating and flooding a new RREQ packet using the route on the route table; And (j) if in step (h) the path on its path table is invalid, updating the path on its path table with the path on the RREQ packet and then flooding the RREQ packet. Path setting method in a wireless network comprising a. The method of any one of claims 1 to 4, wherein each node of the wireless network has a route table in which a route to a destination node is set. In a wireless network system consisting of at least one cluster having a plurality of nodes, The cluster sets any node of the internal nodes as the cluster head, Among the nodes, nodes not set as the cluster head include a route table having route information to a specific destination node. When the cluster head receives an RREQ packet from another node to a specific destination node, the cluster head transmits a RREP packet if the node is a destination node. And flooding the address by inserting the address into the header of the RREQ packet.

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