KR100846189B1 - Best Packet Time-To-Live for Route Discovery in ZigBee Mesh Networks - Google Patents

Abstract

An optimal packet holding time setting method is provided for initializing path discovery of a Zigbee mesh network. In the Zigbee network path initialization initialization method according to an embodiment of the present invention, the method for setting an optimal packet holding time may include receiving depth ( SrcDepth ) of the source node, address ( SrcAddr ) of the source node, and address ( DstAddr ) of the destination node. step; The current depth ( CurDepth ), the upper and lower bounds of the destination node depth ( UpperBound ) and the lower bound ( LowerBound ), the iterative loop value ( RouterIndex ) with the maximum number of routers ( Rm ) as the upper limit, and the number of overlapping branches between the source and destination nodes ( inhValue ). Initializing and setting a value to a temporary variable; Searching for a depth of the destination node using the input information and the set variables; And if the depth value of the destination node is determined as a result of the search, setting the packet holding time by the following Equation.

[Equation]

( D _s is the depth from the coordinator to the source node, D _d is the depth from the coordinator to the destination node, and V _i is the number of branches overlapping between the source and destination in the Zigbee network tree structure)

ZigBee, Packet Duration (TTL), Path Discovery, Node Depth

Description

Best Packet Time-To-Live for Route Discovery in ZigBee Mesh Networks}

1 is a flowchart illustrating a node depth calculation process applied to a method for setting an optimal packet holding time when a path discovery is initialized in a Zigbee network according to an exemplary embodiment of the present invention.

2 and 3 are exemplary views illustrating a process of performing a depth search for an arbitrary destination node by the algorithm of FIG. 1, respectively.

The present invention relates to a method for setting an optimal packet retention time when initializing a path search of a Zigbee mesh network. More specifically, a packet time-to-live (TTL) packet configured by a node constituting a Zigbee network at path initialization is maintained. Time) value determination method.

ZigBee is a wireless communications technology developed for low power, low cost, and low data generation private and industrial wireless application services.

ZigBee defines ZigBee's network, security, and application layers, which are based on the IEEE 802.15.4 standard, which defines the physical and media access control layers.

Device nodes applied to Zigbee are classified into three types according to their roles: PAN coordinator, router, and end device.

The coordinator and router are nodes that form a Zigbee Network's new Personal Area Network (PAN) or have a router function for multi-hop data transmission. Therefore, it is entitled to assign a new address or to perform a route search to set an optimal route.

In contrast, the end device is a node that minimizes the function of the coordinator or the router. The end device is not capable of assigning an address and does not support multi-hop transmission and thus does not participate in path discovery.

Each node in the Zigbee Network has a 16-bit short address.

Since Zigbee PAN coordinator is the creator of Zigbee network, it always has hexadecimal value of 0x0000 and then assigns hierarchically to participating nodes according to the formula formulated by coordinator and end device.

Child nodes participating as coordinators and routers under the router are allocated an address block containing a plurality of 16-bit short addresses from a parent node.

The child node allocated with the address block sets the highest priority address on the address block as its 16-bit short address.

In order to obtain the address block, first, a Cskip (d) value indicating the maximum number of children that can be allocated to its own depth d value of the parent nodes is required.

The value of Cskip (d) is expressed according to the following equation according to the network parameter settings such as the maximum number of routers (nwkMaxRouters: Rm), the maximum number of child nodes (nwkMaxChildren: Cm), and the depth of the maximum children (nwkMaxDepth: Lm). It can be calculated by the formula of 1].

Hereinafter, the parent node allocates corresponding blocks of CSkip (its depth) values in the order of participating child nodes.

Child nodes participating as coordinator and subordinate end devices are allocated one 16-bit short address according to the following formula (2) from the parent node.

In Equation 2, n denotes the order of nodes participating as children, and an address is assigned in the range of 1 or more (Cm-Rm) or less.

The routing of Zigbee mesh network consists of AODV based protocol.

AODV is a routing protocol that establishes a route through a unicast route response message at the destination node for a route request message broadcast from the source node to form an optimal route between the source and destination nodes.

Accordingly, the AODV-based Zigbee routing protocol similarly generates a path discovery control message at the network layer and broadcasts it to the network when performing path discovery.

At this time, the TTL value included in the path search control message header is set to a 2 × nwkMaxDepth value that is twice the default maximum depth nwkMaxDepth of ZigBee.

As described above, since the conventional Zigbee network transmits the path discovery message to all devices in a broadcast manner, there is a possibility that network overhead occurs due to the transmission of a large number of path discovery control messages and the like.

In addition, by participating in unnecessary node path search due to setting the maximum TTL value, there is a problem such as degrading network performance because it can act as a factor to hinder the energy consumption of the node and hinder the flow of other data transmission. .

Therefore, there is a demand for a method for reducing network load due to broadcasting by setting an appropriate packet holding time at the time of path discovery initialization.

An object of the present invention is to provide a method for determining an optimization of a packet time-to-live (TTL) value which is set at the time of path initialization by nodes constituting a Zigbee mesh network.

The objects of the present invention are not limited to the above-mentioned objects, and other objects which are not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above object, the optimal packet holding time setting method in the path discovery initialization of the Zigbee mesh network according to an embodiment of the present invention, the depth of the source node ( SrcDepth ), the address of the source node ( SrcAddr ) and the destination node Receiving address ( DstAddr ) information; The current depth ( CurDepth ), the upper and lower bounds of the destination node depth ( UpperBound ) and the lower bound ( LowerBound ), the iterative loop value ( RouterIndex ) with the maximum number of routers ( Rm ) as the upper limit, and the number of overlapping branches between the source and destination nodes ( inhValue ). Initializing and setting a value to a temporary variable; Searching for a depth of the destination node using the input information and the set variables; And if the depth value of the destination node is determined as a result of the search, setting the packet holding time by the following Equation.

[Equation]

( D _s is the depth from the coordinator to the source node, D _d is the depth from the coordinator to the destination node, and V _i is the number of branches overlapping between the source and destination in the Zigbee network tree structure)

Here, the steps of the iteration loop value (RouterIndex) is in the range of less than the maximum router number (Rm), the repeat loop value (RouterIndex) and lower limit (LowerBound) of the destination node depth of searching the depth of the destination node the step of going to increase the value determines the address (SrcAddr) existence range of the source node; Confirming an address ( DstAddr ) presence range of the destination node while adjusting an inhValue variable between the source and destination nodes so as to correspond to the address ( SrcAddr ) existence range of the source node; Address of the destination node (DstAddr) is located between the destination node upper bound (UpperBound) and lower (LowerBound) value of the depth, of the destination node address (DstAddr) is the equal to the lower limit (LowerBound) Value of the destination node depth In this case, the method may include determining a depth value of the destination node.

In this case, when the address DstAddr of the destination node is not equal to the LowerBound value of the destination node depth, the current node Curdepth and the LowerBound value variable of the destination node depth are increased and reset. Preferably, the depth search step of the destination node is performed again using the reset variable.

In addition, in one embodiment the route search of the ZigBee mesh network according to an initialized at optimum packet holding time setting method of the present invention, the repeat loop value (RouterIndex) the depth of the destination node to the extent of less than the maximum router number (Rm) If the value is not determined, determining whether an address DstAddr of the destination node exists in an end device; And if the address DstAddr of the destination node exists in an end device as a result of the determination, determining the depth value of the destination node by using the same, and if not, alarming that the address information is invalid. .

In all the above process, the upper limit (UpperBound) variable value of the destination node depth is preferably set to the dependent lower limit (LowerBound) variable value of the destination node depth.

Specific details of other embodiments are included in the detailed description and the drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be embodied in various forms, and the present embodiments are merely provided to make the disclosure of the present invention complete and the general knowledge in the art to which the present invention belongs. It is provided to fully inform the person having the scope of the invention, the invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In order to set the packet holding time of the present invention as described above, first, the maximum TTL from the source node to the destination node should be set.

Since the Zigbee Network is assigned a hierarchical address, the upper limit of the TTL value from the source node to the destination address can be regarded as the sum of the distance from the source node to the destination node starting from the coordinator set to address 0x0000. have.

Equation 3 is a formula for setting the TTL maximum value.

D _s represents the depth from the coordinator to the source node, and D _d represents the depth from the coordinator to the destination node. Finally, V _i represents the number of branches overlapping between the source and the destination in the tree structure of the Zigbee network.

In order to set a TTL value to send the route search message from the ZigBee network to be able to measure the depth of the source and the destination nodes in the coordinator, D _s is the calculation known because D _d values.

In this case, since the source and destination nodes may be located on the same overlapping branch, it is necessary to consider the overlapping branch. Therefore, the V _i value must also be calculated.

1 is a flowchart illustrating a node depth calculation process applied to a method for setting an optimal packet holding time when a path discovery is initialized in a Zigbee network according to an exemplary embodiment of the present invention. That is, FIG. 1 illustrates an example of an algorithm for finding a maximum TTL value by receiving a destination address and calculating a depth from a coordinator to a destination node.

As shown in FIG. 1, when the values of SrcDepth (depth of the source node), SrcAddr (16-bit Short Address of the source node) and DstAddr (16-bit Short Address of the destination node) are input (S110), the depth of the destination node is calculated. For this, define a temporary variable called CurDepth (current depth), and initialize the value to 1 since the depth search is performed at nodes below the coordinator (S120).

In addition, since Zigbee node's network address is limited by range of address block according to each depth, define temporary variables called LowerBound and UpperBound to determine destination address according to depth value. Initialize with 0x0001 and 0x0000 respectively.

In addition, in order to perform as many loops as the maximum number of routers Rm for each depth, the value of RouterIndex is initialized to 0.

Finally, inhValue and in order to calculate the overlapping branches with the source and destination nodes A temporary variable called srcInSameBrch is defined and its value is initialized to 0 and false, respectively (S120).

Then, the depth search of the destination node according to the depth is started with each temporary variable initialized as described above.

First, UpperBound corresponding to the address LowerBound CSkip to the LowerBound value to set the value The value is added (S130).

Where CSkip Since the value represents the range of addresses of the destination node that is the child from the parent's point of view, we need to calculate a value of 1 for CurDpeth which represents the depth value currently being searched for. For example, to set the address at UpperBound at depth 1, CSkip at depth 0. You need a value.

Next, in order to calculate the number of overlapping branches when the source is in the same address range where the destination node is located, the LowerBound and UpperBound address of the source node is set in the above process. It is determined whether there is a range (S140). As a result of the determination (S140), if the source is in the corresponding section, srcInSameBrch Value to True It is set (S141).

Subsequently, in order to estimate the section in which the destination node is located, the set LowerBound and UpperBound are compared (S150). At this time, if the destination node is located within the range, it is checked whether the srcInSameBrch value is true (S151). When the result source of the determination (S151) is in the same section as the destination, since the source is in the same overlapped branch, the inhvalue is increased and the srcInSameBrch value is initialized to false (S154).

Subsequently, it is determined whether the address of the destination node matches LowerBound (S152).

Where LowerBound is currently set to the address of the destination node If the match values CurDepth the depth that is currently browsing is because the depth of the destination node, in order to reduce the current of a number of nested up to the sum of the SrcDepth and CurDepth, stored so far inhValue Optimal maxTTL by subtracting the value multiplied by 2 The value is calculated (S180).

If the LowerBound and the destination address do not match in the process S151, since the destination address is not located in the current depth, the values for the LowerBound and the CurDepth for the next depth are 1 for each of the next address. The process of S130 is repeated to increase (S153).

In step S150, the destination address is LowerBound and UpperBound. RouterIndex if not present within It is determined whether the value exceeds the maximum number of routers (S160).

As a result, the current RouterIndex The value is Rm If within, RouterIndex is used to find the starting address of the next router in the current depth. The value is increased by 1 and the process of step S130 is repeated after storing the currently set UpperBound value in LowerBound (S161).

When RouterIndex exceeds Rm in step S160, since the address search for the router is finished, the search for the end device is performed.

End device is currently stored UpperBound ideal Since the value of the UpperBound and the Cm is added to the range obtained by subtracting the Rm , it is determined whether the destination address exists in this range (S170).

If the end device is within this range as a result of the determination (S170), CurDepth Since the value is a depth value of the destination node, the optimal maxTTL is passed through the step S180. Calculate the value. If the destination address does not exist within this range, it means an invalid address and an error message is output and the calculation is terminated.

 2 and 3 are exemplary diagrams illustrating a process of performing a depth search for an arbitrary destination node by the algorithm of FIG. 1, and FIG. 2 illustrates a case where a source node and a destination node are located on different branches. 3 shows a case where the source node and the destination node are located in overlapping branches.

In FIG. 2 and FIG. 3, it is assumed that the network initial constants of each implementation example are as follows.

1) nwkMaxDepth = 3

2) nwkMaxChildren (maximum number of children) = 8

3) nwkMaxRouters = 4

To help understand this embodiment, Cskip values for each depth are shown in a table in advance at the top of FIGS. 2 and 3.

First, referring to FIG. 2, where there are no overlapping branches, when node 120 transmits data to node 71, the node 120 starts with 0x0000, the address of the PAN coordinator, to search for the depth of node 71. Perform an algorithm to calculate depth.

That is, as described in FIG. 1, first , 2, 120, and 71 are input to SrcDepth , SrcAddr , and DstAddr , respectively, and the CurDepth , LowerBound , UpperBound , RouterIndex , and inhValue values are initialized to 1, 0x0001, 0x0000, 0, 0, respectively. .

Next, LowerBound to save the UpperBound corresponding to LowerBound This is obtained by adding the value 0x0001 and the value of Cskip ( CurDepth- 1) . At this time, since Cskip (0) is 41, UpperBound is assigned to 42.

And SrcAddr Check that the value 120 is between LowerBound and UpperBound , in which case 120 does not increase the value of inhValue because it is not between these values.

Then, DstAddr It checks whether the value 71 is between LowerBound and UpperBound , and since 71 is also not between them, check that the router index value does not exceed the maximum number of routers.

In this case, since the value of the router index is 0, the value of the router index is increased by 1 and the upper bound is replaced by the LowerBound , and then returned to the beginning.

Therefore, LowrBound and UpperBound are 42 and 83, respectively.

again, Srcaddr Check that the value 120 is between LowerBound and UpperBound . But 120 is not between them inhValue DstAddr again without changing the value Check if the value 71 is between LowerBound and UpperBound .

71 represents LowerBound and UpperBound You can see that it is located in between. So, next, we check to see if LowerBound and 71 are equal, where 71 is LowerBound. Because it is different from the value, we increase the CurDepth by 1 LowerBound also increases by 1.

CurDepth is 2 and LowerBound is 43.

Then ask the UpperBound corresponding to LowerBound, is a value of 52 plus the LowerBound and Cskip (CurDepth-1). Since CurDepth is 2 Cskip (1) plus 9.

If the above process is repeated until 71, DstAddr , is located between LowerBound and UpperBound , when the router index value is 3, the values of LowerBound and UpperBound are 70 and 79, respectively.

Again, this is 120 SrcAddr LowerBound Upperbound Make sure it's in between. Since SrcAddr is between 120, DstAddr is checked without changing the inhValue value.

You can see that the 71st DstAddr is between this LowerBound and UpperBound . Therefore, make sure that LowerBound and DstAddr are the same.

As a result, LowerBound and DstAddr are not the same as 70 and 71, respectively, so we increase CurDepth by 1 LowerBound is also increased by 1, and UpperBound is obtained.

here, CurDepth becomes 3 and LowerBound becomes 71. Thus, UpperBound The value is 72 LowerBound, 71, It is the same as DstAddr 71, so it is a valid value.

At this time, CurDepth = 3, SrcDeppth = 2, Since inhValue = 0, the value of maxTTL is 5 (3 + 2-2 x 0 = 5) by Equation 3 above.

Next, a process in which the node 120 transmits data to the node 84 when there are overlapped branches will be described with reference to FIG. 3.

Referring to Figure 1, SrcDepth, SrcAddr, each type 2, 120, 84 and the DstAddr CurDepth, LowerBound, UpperBound, RouterIndex, inhValue Initialize the value.

In order to obtain the following UpperBound corresponding to a LowerBound LowerBound This is obtained by adding the value 0x0001 and the value of Cskip ( CurDepth- 1) . It is assigned to 42 here.

In addition, it is checked whether the value of SrcAddr is between LowerBound and UpperBound . At this time, 120 is not positioned between them, so it is checked whether the DstAddr value is between LowerBound and UpperBound without increasing the inhValue value.

However, 84 is also not located between these ranges, so after checking that the router index value does not exceed the maximum number of routers, if not, the router index is increased by one and the loop is performed again.

Repeating this process, when the router index value is 2, the values of LowerBound and UpperBound are 83 and 124, respectively.

Again, SrcAddr 120 is the LowerBound and UpperBound Make sure it's in between.

As a result, SrcAddr , 120, is located between them, After increasing the value of inhValue by 1, we check whether DstAddr is between LowerBound and UpperBound .

Then, DstAddr of 84 degrees with the LowerBound UpperBound You can see that it is in between.

Therefore, make sure that LowerBound and DstAddr are equal. LowerBound and DstAddr are not the same because they are 83 and 84, respectively.

Therefore, increase CurDepth by 1 Was increased, the LowerBound obtain the UpperBound.

in this case LowerBound becomes 84 and UpperBound becomes 93.

Since SrcAddr 120 is not between LowerBound and UpperBound , DstAddr sets LowerBound and UpperBound without changing inhValue . Check whether it is located in between.

DstAddr is LowerBound and UpperBound In between, and also LowerBound This is the same value, so this value is valid.

At this time, CurDepth = 2, SrcDepth = 2, and inhValue = 1, and according to Equation 3, the maxTTL value is 2 (2 + 2-2 × 1 = 2).

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that. Therefore, the embodiments described above are to be understood in all respects as illustrative and not restrictive.

According to the method of setting the optimal packet holding time in the path discovery initialization of the Zigbee mesh network of the present invention as described above, the optimum upper limit value can be applied to the maximum TTL value setting.

Accordingly, not only the network load due to broadcasting can be reduced, but also the participation of unnecessary path discovery of the node can be reduced.

As a result, the energy consumption of the node can be reduced and the bandwidth of the entire network can be reduced, thereby increasing network performance such as data throughput per unit time.

In addition, the depth from the source node to the destination node can be searched, so that it can be applied in a tree or mesh structure, and can be used in end devices without routing capability. The sensor network has the advantage of being able to be applied to a general purpose.

Claims (5)

Receiving depth SrcDepth of the source node, address SrcAddr of the source node, and address DstAddr of the destination node; The current depth ( CurDepth ), the upper and lower bounds of the destination node depth ( UpperBound ) and the lower bound ( LowerBound ), the iterative loop value ( RouterIndex ) with the maximum number of routers ( Rm ) as the upper limit, and the number of overlapping branches between the source and destination nodes ( inhValue ). Initializing and setting a value to a temporary variable; Searching for a depth of the destination node using the input information and the set variables; And If the depth value of the destination node is determined as a result of the search, setting the packet holding time according to the following equation comprising: setting the optimal packet holding time when initializing the path search of the Zigbee mesh network. [Equation]

( D _s is the depth from the coordinator to the source node, D _d is the depth from the coordinator to the destination node, and V _i is the number of branches overlapping between the source and destination in the Zigbee network tree structure) The method of claim 1, Searching for the depth of the destination node, Within the repeat loop value (RouterIndex) the range of less than the maximum router number (Rm), going to the repeated increase of the lower limit (LowerBound) value of the loop value (RouterIndex) and the destination node depth address of the source node (SrcAddr) Determining a range of existence; Confirming an address ( DstAddr ) presence range of the destination node while adjusting an inhValue variable between the source and destination nodes so as to correspond to the address ( SrcAddr ) existence range of the source node; Address of the destination node (DstAddr) is located between the destination node upper bound (UpperBound) and lower (LowerBound) value of the depth, of the destination node address (DstAddr) is the equal to the lower limit (LowerBound) Value of the destination node depth And determining a depth value of the destination node when the path discovery initialization of the Zigbee mesh network is initiated. The method of claim 2, If the address DstAddr of the destination node is not the same as the LowerBound value of the destination node depth, the current depth CurDepth and the LowerBound value variable of the destination node depth are increased and reset. A method for setting an optimal packet holding time when initializing a path search of a Zigbee mesh network, wherein the depth search step of the destination node is performed again using the reset variable. The method according to any one of claims 1 to 3, The upper limit (UpperBound) value of the variable of the destination node depth is, the lower limit of the destination node depth by the expression of maintaining optimum packet upon initialization a path search of the ZigBee mesh network, characterized in that the independent set to the (LowerBound) value of variable How to set the time. [Equation] UpperBound variable = LowerBound variable + Cskip (CurDepth-1) (Where Cskip is the depth of the node itself) The method of claim 4, wherein Determining that if the value of the iteration loop (RouterIndex), this depth value of the destination node may not be determined in a range less than the maximum number of routers (Rm), address (DstAddr) of the destination node is present in the end device; And As a result of the determination, if the address DstAddr of the destination node exists in the end device, the depth value of the destination node is determined using the address DstAddr of the destination node, and if not, alarming that the address information is invalid. A method for setting an optimal packet retention time in initializing path discovery of a Zigbee mesh network further comprising a step.

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