JP4442607B2 - Network analysis system and method - Google Patents

Description

  The present invention relates to a network analysis system and method, and can be applied to, for example, a test of a communication timing control function and a state analysis of an operating network in a wireless network that autonomously determines data transmission timing.

  Patent Document 1 and Patent Document 2 describe a method in which a plurality of nodes distributed and arranged in a network autonomously determine time slots.

  Each terminal (node) transmits a communication timing control signal almost periodically. In addition, a data transmission time slot is secured by receiving a communication timing control signal transmitted from surrounding terminals and adjusting the transmission timing of the communication timing control signal from the own terminal in consideration of the reception timing. A terminal that intends to transmit a data signal to the network transmits the communication timing control signal from its own terminal until immediately before the other terminal transmits the communication timing control signal to the next time slot. Get the right to send.

In an environment where nodes are installed over a wide area, when data is transmitted from a certain node to a remote node, it is realized by multi-hop transfer that relays intermediate nodes. In a multi-hop transfer environment, a hidden terminal problem may occur and signal collision may occur. However, in the technique described in Patent Document 1, it is directly connected to other nodes belonging to a reach of more than twice the data signal reach. By performing the communication timing, the data transmission timing is prevented from overlapping. It is difficult to accurately control the radio wave reach of a wireless communication system. In the technique described in Patent Document 1, a communication timing control signal is transmitted at the same arrival distance as that of a data signal, and the received node further transfers the communication timing control signal, so that it belongs to an arrival range more than twice that of the data signal. Controls communication timing with nodes.
JP 2006-211564 A JP-A-2005-094663

  In a network that performs communication timing control as described above, the network status can be known by measuring the reception interval of the communication timing control signal. In a network environment in which each node is installed in a narrow range, it is possible by intercepting transmission packets of all nodes with a packet capture device.

  However, in an environment where nodes are installed in a wide range, the reach range varies depending on the installation position. Therefore, even if the transmission timing from the node is collected at the packet capture point, it does not coincide with the reception timing of each node. The reception timing can be known by providing a packet capture function to all nodes. However, a node normally receives only packets addressed to itself and broadcast packets, and a special function is required for the node to receive all packets. In addition, there is a load due to processing all packets.

  In general, the network efficiency is better when the node density is lower and uniform, so it is only necessary to design the network so that the nodes are uniform and install the nodes. The node density can be grasped by measuring how many nodes each node receives a packet from. When the number of nodes is small, it is possible to optimize the node arrangement by repeating the above-described measurement after changing the state by moving the positions of some of the nodes. However, when the number of nodes increases, it is difficult to repeat the trial and error work as described above. Therefore, it is sufficient if there is a means for knowing what network state is changed before adding or moving a node. However, it is difficult to estimate the number of reception nodes at all positions in the network, including positions where nodes are not installed, because the radio wave arrival distance differs depending on the installation positions and node characteristics of the nodes. Therefore, it is difficult to know how to move each node to optimize network efficiency.

  Also, in a large network, it is difficult to capture packets sent by all nodes with a single device, so how the entire network changes when the installation status of a certain range is changed. It is difficult to know immediately what to do.

  Therefore, there is a demand for a network analysis system and method that can observe the state of the network in almost real time over the entire area of the wireless network.

The first aspect of the present invention includes a plurality of nodes having communication timing control means for autonomously determining a time slot capable of transmitting a data signal from the own node based on transmission / reception of a communication timing control signal between the nodes. In a network analysis system for analyzing a wireless network, (1) having one or a plurality of packet capture devices and a packet analyzer, (2) each of the nodes is a source node address, a neighboring node located in the vicinity of the node And (3) each of the packet capture devices intercepts the communication timing control signal on the wireless network and sends the intercept information to the packet analyzer. (4) The packet analyzer is configured for each node The node information storage means for storing reception range information including information on neighboring nodes that have transmitted the communication timing control signal that the local node has received, and the transmission source node of the communication timing control signal intercepted by the packet capture device, Information updating means for updating the reception range information stored in the node information storage means based on the number of neighboring nodes and neighboring node addresses of the intercepted communication timing control signal, and stored in the node information storage means Output information forming means for forming output information from the information, and output means for outputting the formed output information.

The second aspect of the present invention is composed of a plurality of nodes having communication timing control means for autonomously determining a time slot capable of transmitting a data signal from the own node based on transmission / reception of the communication timing control signal between the nodes. Yes in network analysis method for analyzing a radio network, which has a (1) one or more packet capturing device and a packet analyzer, the packet analyzer, the node information memory means, information updating means, the output information forming means and outputting means (2) Each packet capture device intercepts the communication timing control signal on the wireless network and sends intercept information to the packet analyzer. (3) The node information storage means The node sent a communication timing control signal that could be received. (4) The information update unit is stored in the node information storage unit related to the transmission source node of the communication timing control signal intercepted by the packet capture device . The reception range information is updated based on the number of neighboring nodes and neighboring node addresses of the intercepted communication timing control signal . (5) The output information forming means outputs output information from the information stored in the node information storage means. (6) The output means outputs the output information formed.

  According to the present invention, a radio composed of a plurality of nodes having communication timing control means for autonomously determining a time slot capable of transmitting a data signal from the own node based on transmission / reception of the communication timing control signal between the nodes. The state of the network can be observed in almost real time over the entire area of the network.

(A) First Embodiment Hereinafter, a first embodiment of a network analysis system and method according to the present invention will be described in detail with reference to the drawings.

(A-1) Configuration of First Embodiment FIG. 1 is a block diagram showing a schematic configuration of a network analysis system and a radio network to be analyzed according to the first embodiment.

  The wireless network to be analyzed has a plurality (20 in the case of FIG. 1) of nodes N1 to N20 that are distributed.

  Each of the nodes N (N1 to N20) corresponds to, for example, the nodes described in Patent Document 1 and Patent Document 2, and basically, the time slot (transmittable from itself) can be autonomously transmitted and received by a communication timing control signal. Period) and data is transmitted in the time slot. In the following description, it is assumed that the communication timing control signal is transmitted / received by a packet (a packet related to the communication timing control signal is referred to as a control packet).

  It is assumed that each node N transmits a packet (control packet (including an analysis target packet described later)) so as to reach about 5 to 10 surrounding nodes. For example, the node N1 transmits a packet so as to reach the nodes N3, N4, N6, N7, and N11. When transmitting a packet to a remote node, it may be transmitted by multi-hop transfer. For example, when transmitting from the node N1 to the node N5, the nodes N2, N3, and N4 sequentially relay and the packet arrives at the node N5.

  In the case of the first embodiment, each node N forms a packet to be analyzed, which will be described later, in addition to the time slot autonomous determination function described in Patent Document 1 and Patent Document 2, and intermittently transmits the packet. (E.g., transmitting once every predetermined period).

  The network analysis system 10 according to the first embodiment includes a plurality (four in the case of FIG. 1) of packet capture devices 11-1 to 11-4, a packet analyzer 12, a display device 13, and an input device 14.

  The packet capture device 11 (11-1 to 11-4) intercepts packets on the network (control packets (including analysis target packets described later)) and inputs them to the packet analyzer 12. The connection form between each packet capture device 11 and the packet analyzer 12 may be either wired or wireless. Since only one packet capture device 11 can receive a packet transmitted by all nodes, a plurality of packet capture devices 11 may be provided, and FIG. 1 shows an example in which four packets are arranged (the second described later). It is a requirement that a plurality of the embodiments exist). Note that after measuring a point where one packet capture device 11 is present, the packet capture device 11 may be moved to receive a packet. That is, one packet capture device or a plurality of packet capture devices may be used as long as packet interception at a plurality of points can be executed.

  For example, the packet analyzer 12 is mainly configured with software on a personal computer. In other words, the packet analyzer 12 is configured, for example, by installing a network analysis program in a personal computer having a communication function. Functionally, the packet analyzer 12 includes a packet analysis unit 21, a node information update unit 22, a reach range calculation unit 23, a display control unit 24, a simulation unit 25, and a node information table 26 as shown in FIG.

  The packet analysis unit 21 determines whether or not the packet received by the packet capture device 11 is an analysis target packet. If the packet is an analysis target packet, the packet analysis unit 21 analyzes the packet contents and extracts predetermined information. This is given to the calculation unit 23 and the node information update unit 22.

  FIG. 3 is an explanatory diagram showing the format of the analysis target packet. In FIG. 3, the analysis target packet is a kind of control packet, and has items (fields) of destination address, source address, number of neighboring nodes, neighboring node address, and neighboring node information. There are as many neighboring node addresses and neighboring node information as the number of neighboring nodes.

  Note that the control packet includes only the destination address and the source address. Therefore, it is possible to determine whether the packet is an analysis target packet or a control packet based on the number of neighboring nodes, the neighboring node address, and the presence / absence of neighboring node information. Note that a packet type item that can identify whether the packet is an analysis target packet or a control packet may be provided as a packet item.

  The destination address is the node address of the destination of the packet. Since the analysis target packet is also a control packet, a broadcast address is described in the destination address. However, when the analysis target packet is transferred by multi-hop, information indicating the necessity of transfer such as the next transfer destination address is described. The analysis target packet is a control packet intended to be intercepted by a nearby packet capture device 11.

  The data signal communicated in the time slot is communicated by a different communication method such as a different frequency from the analysis target packet and the control packet, and can be distinguished from the analysis target packet and the control packet. When a similar communication method is applied to the data signal, type information for identifying the packet related to the data signal and the analysis target packet may be included in the packet.

  The number of neighboring nodes represents the number of neighboring nodes that can receive the control packet in the transmission source mode of the analysis target packet. Depending on the radio wave conditions, the control packet from a certain node may or may not be received. In such a case, for example, the vicinity depends on whether the number of receptions within a predetermined time is equal to or greater than the threshold number. Determine if it is a node.

  The neighboring node address is the node address of the neighboring node, and the neighboring node information includes, for example, the reception intensity of the control packet from the neighboring node and the transmission source node autonomously assigns a fixed period to the own node and the neighboring node. In the case (see Patent Document 2), the timing difference between the allocation period of the own node and the allocation period of the neighboring node, the number of times of receiving control packets from the neighboring node within a predetermined time, etc. Information applies.

  The control packet that each node transmits as a communication timing control signal may also be composed of the items shown in FIG. 3, or may include items other than those shown in FIG. Note that all control packets may be analysis target packets. In other words, there is no need to distinguish between the control packet and the analysis target packet.

  Returning to FIG. 2, the reach range calculation unit 23 uses the information of one or a plurality of received analysis target packets and the information held in the node information table 26 to reach to which range the control packet transmitted by the transmission source node reaches. It is what calculates.

  The display control unit 24 controls display of node position information, transmission source information of reception analysis target packets, packet reachability information, and the like on the display device 13.

  The node information updating unit 22 updates storage information in the node information table 26 with node information obtained by analyzing the collected reception analysis target packet.

The simulation unit 25 uses the stored information in the node information table 26, the position of each node, and the state change amount such as the transmission power from each node to change the state of the network, thereby changing the state of the network. This is a prediction calculation (simulation). Information that needs to be input before starting the simulation is input from the input device 14 .

  In the first embodiment, it is assumed that the position of each node is measured in advance and the node position information is registered in the packet analyzer 12 (node information table 26 thereof).

  FIG. 4 is an explanatory diagram showing a configuration example of the node information table 26. In FIG. 4, the node information table 26 describes, for each node, the node address, installation position information, the number of neighboring nodes, and the reception range information of the node. In the reception range information, the node address of the neighboring node where the node has received the control packet is described together with the neighboring node information. As the neighboring node information, information on one or more items that can be measured among the items related to the positional relationship with the neighboring node is described. As the neighboring node information, the neighboring node information of the analysis target packet that is the transmission source of the node may be applied as it is, or the neighboring node information of the analysis target packet may be processed (for example, reception strength) If so, it may be obtained by averaging the reception strengths of a plurality of analysis target packets).

  The node installation position information may be input via the input device 14, or a GPS receiver or the like may be mounted on each node so as to be captured from the node.

(A-2) Method for Determining Communication Timing (Time Slot) at Each Node Next, the network analysis system according to the first embodiment is assumed before the operation of the network analysis system according to the first embodiment is described. An example (a method described in Patent Document 2) of a method for each node to autonomously determine a time slot will be described. Note that the method described below is an example, and each node may apply a method in which a part of the method is changed (for example, the method described in Patent Document 1).

  As described above, each node can receive a communication timing control signal (control packet) transmitted by a neighboring node (another node existing in a range where the transmission radio wave of the node reaches).

The communication timing calculation means (not shown) of each node forms a phase signal that defines the communication timing at the node based on the received communication timing control signal. Here, assuming that the node is the node i and the phase value of the phase signal at time t is θi (t), the communication timing calculation means outputs the phase signal θi (t) for each change as shown in the equation (1). ). The expression (1) is an expression modeling nonlinear vibration, but an expression modeling other nonlinear vibration can also be applied. Further, the phase signal θi (t) can be regarded as a state variable signal of the node.

  Expression (1) represents a rule for changing the rhythm of nonlinear vibration of the phase signal θi (t) of the own node i in accordance with the received communication timing control signal. In the equation (1), the first term ω (natural angular frequency parameter) on the right side represents a basic change rhythm included in each node, and the second term on the right side represents a nonlinear change. Here, the value of ω is, for example, the same value for the entire system. The function Pk (t) represents a communication timing control signal received from a neighboring node k (k is assumed to be 1 to N), and the function R (θi (t), σ (t)) is transmitted from another node. This is a phase response function that expresses a response characteristic that changes its basic rhythm in response to the reception of the communication timing control signal, for example, in accordance with equation (2).

  Expression (2) represents that the phase response function is defined by a sine wave having a phase value in which random noise is superimposed on the opposite phase of the phase signal θi (t) at time t.

  Non-linear characteristics in which neighboring nodes are in opposite phases (vibration phase is inverted phase) are realized, and collision avoidance is attempted using the characteristics. That is, an appropriate time relationship (time difference) is formed at the timing when the phase signal value of each node becomes the same value so that the transmission timing of the communication timing control signal between neighboring nodes does not collide.

  In the equation (2), the constant term π [rad] representing the function σ (t) functions as a non-linear characteristic in which neighboring nodes are out of phase with each other, and the random noise function φ (t) It functions to give random variability to the nonlinear characteristic (the function φ (t) follows, for example, a Gaussian distribution with an average value of 0). Here, the reason why random variability is given to the non-linear characteristic is to deal with a phenomenon that the system does not reach the target stable state (optimal solution) and falls into another stable state (local solution). Because.

  In the equation (2), the form using the sine function is shown as the simplest example of the phase response function R (θi (t), σ (t)), but other functions may be used as the phase response function. good. Further, instead of the constant term π of the function σ (t), a constant λ other than π (0 <λ <2π) may be used. In this case, neighboring nodes are not in antiphase but in different phases. Function.

  The meaning of the above-described function of the communication timing calculation means will be described in detail with reference to FIG. The state change shown in FIG. 5 is also related to the transmission function of the communication timing control signal.

  FIG. 5 shows a relationship formed between a target node (own node) and a neighboring node (other node) j when attention is paid to a certain node i, that is, a phase relationship between the respective nonlinear vibration rhythms. Shows how the changes over time.

  FIG. 5 shows a case where there is one neighboring node j for the node of interest i. In FIG. 5, the motion of the two mass points rotating on the circle represents the nonlinear vibration rhythm corresponding to the node of interest and the neighboring nodes, and the angle of the mass point on the circle represents the value of the phase signal at that time. Yes. The motion of the point where the rotational motion of the mass point is projected on the vertical or horizontal axis corresponds to the nonlinear vibration rhythm. By the operation based on the formulas (1) and (2), the two mass points try to be in opposite phases to each other. As shown in FIG. 5A, the phases of the two mass points are close to each other in the initial state. However, with the passage of time, the state (transient state) shown in FIG. 5B changes to a steady state in which the phase difference between the two mass points is almost π as shown in FIG. 5C.

  Each of the two mass points rotates with the natural angular frequency parameter ω as a basic angular velocity. Here, when an interaction based on transmission / reception of a communication timing signal occurs between nodes, these mass points change (slow and steep) angular velocities, respectively, and eventually reach a steady state in which an appropriate phase relationship is maintained. This operation can be regarded as forming a stable phase relationship by repelling each other while the two mass points rotate. In the steady state, as described later, when each node transmits a communication timing control signal when a predetermined phase α (for example, α = 0), the transmission timing in each node forms an appropriate time relationship. Will be.

  The formation of the above-described stable phase relationship (steady state) has a very adaptive (flexible) property with respect to changes in the number of neighboring nodes. For example, it is assumed that one neighboring node is added when there is one neighboring node with respect to the node of interest and a stable phase relationship (steady state) is formed. The steady state once collapses, but after passing through the transient state, a new steady state in the case where there are two neighboring nodes is reformed. In addition, when a neighboring node is deleted or does not function due to a failure or the like, an adaptive operation is performed in the same manner.

  The communication timing calculation means determines the transmission timing of the communication timing control signal based on the obtained phase signal θi (t) and instructs transmission. That is, when the phase signal θi (t) reaches a predetermined phase α (0 ≦ α <2π), the transmission of the communication timing control signal is instructed. Here, it is preferable that the predetermined phase α is previously unified in the entire system. In the following description, it is assumed that α = 0 is unified throughout the system. In the example of FIG. 5, since the phase signals θi (t) and θj (t) of the node i and the node j are shifted by π in the steady state, the system is unified to α = 0. However, the transmission timing of the communication timing control signal from the node i and the transmission timing of the communication timing control signal from the node j are shifted by π.

  The communication timing control signal is transmitted when the phase signal θi (t) of the communication timing calculation means reaches a predetermined phase α.

  The tuning determination unit in the communication timing calculation means is configured so that the mutual adjustment of the transmission timing of the communication timing control signal performed between the own node and one or a plurality of neighboring nodes is “transient state” (see FIG. 5B) or It is determined which state is “steady state” (see FIG. 5C) (tuned determination is performed). The tuning determination unit observes the reception timing of the communication timing control signal and the transmission timing of the communication timing control signal from its own node, and the time difference between the transmission timings of a plurality of nodes that exchange the communication timing signal is sufficient and time If it is stable, it is determined to be “steady state”. The tuning determination unit uses the phase signal θi (t) as a signal for capturing the transmission timing of the communication timing control signal from the own node.

  The tuning determination unit determines a time slot from the node for each period of the phase signal θi (t) when the tuning determination result indicates “steady state”. For example, in the case of FIG. 5C, the time slot from the node i is determined within a period in which the phase signal θi (t) is 0 to π. Note that it can be recognized that the neighboring node j sets a time slot within the period in which the phase signal θi (t) is π to 2π.

(A-3) Operation of the First Embodiment Next, the operation (network analysis method) of the network analysis system according to the first embodiment, particularly the operation of the packet analyzer 12 will be described.

  Here, in the case of the first embodiment, the processing of the packet analyzer 12 is roughly (1) creation and update of the node information table 26, (2) analysis and display processing of communication timing and reach range, and (3). The simulation can be divided into three types after the node state change.

  FIG. 6 is a flowchart showing operations for creating and updating the node information table 26 in the first embodiment.

  The packet received by each packet capture device 11 is transferred to the packet analyzer 12 and captured by the packet analysis unit 21 of the packet analyzer 12. The packet analysis unit 21 of the packet analyzer 12 determines whether or not the received packet is an analysis target packet (S11). If it is not an analysis target packet, it is discarded.

  If the received packet is an analysis target packet, the packet analysis unit 21 extracts the number of neighboring nodes, the neighboring node address, and the neighboring node information from the analysis target packet (S12), and the node information update unit 22 receives the received analysis target packet. The corresponding row of the node information table 26 having the packet source address as the node address is searched, and the number of neighboring nodes and the reception range information in the row are updated to the information extracted by the packet analysis unit 21 (S13).

  In addition, when the fluctuation of the radio wave condition is large, information of neighboring nodes described for each received analysis target packet changes. In such a case, information on the percentage of neighboring packets included in the past analysis target packet is included in the neighboring node information. It should be suppressed.

  FIG. 7 is a flowchart showing communication timing and reachable range analysis and display processing in the first embodiment. FIG. 7 also describes the same processing as in FIG. 6 described above.

  FIG. 8 is an explanatory diagram showing a display example of the analysis result of the packet analyzer. FIG. 8A shows an initial display state (state when the display is reset) before executing analysis of any analysis target packet. In FIG. 8A, each small square displayed represents a node, and the display position corresponds to the position of each node (see the installation position item in FIG. 4). The display example of FIG. 8 corresponds to the installation position of each node as shown in FIG.

  The packet received by each packet capture device 11 is transferred to the packet analyzer 12 and taken into the packet analysis unit 21 of the packet analyzer 12 to determine whether or not the received packet is an analysis target packet (S21).

  If it is not an analysis target packet, the process proceeds to step S25 described later. If it is not the analysis target packet, it may be discarded.

  If the packet is an analysis target packet, the packet analysis unit 21 extracts a transmission source node address from the analysis target packet in order to calculate the reachable range (S22). Then, the reach range calculation unit 23 selects all other nodes that include the extracted transmission source node address as the neighboring node address of the node information table 26 (S23). For example, in the case where the node information table 26 is as shown in FIG. 4 and the transmission source node address is “6”, when another node including the node address “6” as a neighbor node address is searched, the node address “1” ”,“ 2 ”,“ 7 ”, and“ 8 ”are selected.

  The transmission source node address and the selection information by the arrival range calculation unit 23 are given to the display control unit 24, and the display control unit 24 visually displays, for example, the range where the packet from the transmission source of the current analysis target packet reaches. It is displayed on the device 13 (S24). As shown in FIG. 8B, the display control unit 24 marks the node N6 that is the transmission source node (in FIG. 8B, the node graphic is marked in black), and step S2-3. The range including all the other nodes N1, N2, N7, and N8 selected in (1) is marked by displaying a curve representing a boundary line. The boundary curve may be an outer shape curve of the largest predetermined shape (for example, a circle or an ellipse) including only the transmission source node and other selected nodes, and is provided with boundary line information that connects intermediate positions between the nodes in advance. Alternatively, it may be formed from the boundary line information between the selected other node and the non-selected nodes around the other node. The broken line in FIG. 8B is a boundary curve in such a case.

  Note that the method for displaying the packet reachable range is not limited to the method for displaying the boundary line curve as described above, and the packet reachable range may be indicated by other methods. For example, the nodes in the range may be displayed in a color different from the display color of the node in the initial state or the display color of the transmission source node. Also, for example, as shown in FIG. 9, an assumed reach range is set in advance, the assumed reach range from the transmission source node related to the received packet is displayed in a circle or the like, and within the reach range extracted from the node information table 26 A node may be marked. According to this display method, it is possible to determine at a glance that a packet (radio wave) has reached a wider range than the assumed reachable range or has not been received by a node to be reached.

  When the analysis target packet from another node is received and the radio wave arrival range is displayed while displaying the packet arrival range of a certain node, for example, as shown in FIG. FIG. 8C is an example when the reachable range of the node N14 is added and displayed while the reachable range of the node N6 is displayed. Node N8 overlaps the reach of both node N6 and node N14, which indicates that node N8 has a hidden terminal problem. Even if either the node N6 or the node N14 tries to transmit data to the node N8, time slots may be allocated at the nodes N6 and N14 so that a collision of data signals from the nodes N6 and N14 occurs. When such an assignment is made, the node N8 cannot receive it. When such a state occurs, and the network is in a normal state, the method described in Patent Document 1 eliminates the hidden terminal problem by the node N8 performing timing adjustment.

  When the display control unit 24 performs the display process as described above, the display control unit 24 sets a display time timer (part of the process of S24). The display time is the minimum time slot time that should be assigned to each node as a data signal transmission time.

  If there is no display for the display time, it is confirmed whether or not there is a node displaying the packet reach (S25). If there is no node being displayed, the process returns to step S21, and monitoring of received packets is continued.

  If there is a node displaying the packet reach, it is determined whether or not the display time for any of the nodes being displayed has elapsed (S26). If no display time has elapsed for any of the nodes, the process returns to step S21 to continue monitoring received packets.

  When the display time of one of the nodes being displayed has elapsed, the display control unit 24 ends the display of the reachable range for that node (S27), and then returns to step S21 to monitor the received packet. continue.

  For example, in the case where one node is being displayed, when the display is performed for a predetermined display time and the display ends, the display state changes from FIG. 8B to FIG. 8A.

  If the frame period (period in which nodes autonomously assign time slots (corresponding to one rotation in FIG. 5)) is short, the display time of the reachable range is short even if the above display is performed, and the hidden terminal problem occurs. It is difficult to determine whether you are doing it. When the frame period is set to be short, the display state at the time when the hidden terminal problem occurs may be fixed for a predetermined time so that the reachable range can be easily identified. After the collection and the display of the reach range are started, slow reproduction display such as 1/10 times may be performed.

  Next, the simulation operation when the node state is changed will be described.

  FIG. 10A is an explanatory diagram illustrating a display example of the analysis result of the reception node number distribution by the packet analyzer 12. FIG. 10 (a) receives the control packets from the surrounding nodes when the position in the area where the node exists is coordinated and the packet capture device 11 is installed at each coordinate position. It shows the analysis result of whether it can be done.

  When the simulation unit 25 of the packet analyzer 12 requests the analysis result of the reception node number distribution from the input device 14, the simulation unit 25 refers to the storage information of the node information table 26 while referring to the storage information in the node information table 26 as follows. An analysis result is obtained and displayed on the display device 13 by the display control unit 24.

  Actually, the number of receiving nodes at the coordinate position where the node is located is a value obtained by adding “1” related to the own node to the number of neighboring nodes in the packet to be analyzed that is the transmission source of the node (packet capture device). 11 is considered, and “1” related to the own node is added). For example, if a node exists at the position of the coordinate “B2” and the number of neighboring nodes in the analysis target packet is “8”, “9” as a result of adding “1” related to the own node. Is the number of receiving nodes in the receiving node number distribution.

  As the number of receiving nodes at the coordinate position where no node exists, a measurement result of the control packet by the packet capture device 11 or an estimated value is displayed.

  The measurement result (number of reception nodes) of the control packet by the packet capture device 11 is stored in the node information table 26 in the node information table 26 by storing the number of reception nodes at the coordinate position obtained using the packet capture device 11. Use. Here, the node information table 26 may store the number of reception nodes obtained by collecting work while the worker moves the packet capture device 11. If the packet capture device 11 is fixedly installed, the measurement result (the number of receiving nodes) may be used only for the fixedly installed coordinates. In this case, each packet capture device 11 has the number of types of the transmission source node of the analysis target packet or control packet that is effectively received within the measurement period as the number of reception nodes (for example, in the process shown in FIG. Such a counting step may be included).

  FIG. 11 is an explanatory diagram of an example of a method for estimating the number of reception nodes at a certain coordinate position. From the reach of each node, the number of receiving nodes at an arbitrary coordinate position is estimated. In FIG. 11, the coordinate position where the reach ranges of the nodes NA and NB overlap is 2 reception nodes, and the coordinate position where the reach ranges of the nodes NA, NB and NC overlap is 3 receive nodes. The number of receiving nodes at the coordinate position where the number of nodes is unknown is determined.

  For example, when the time obtained by dividing the frame period into 8 is set as the minimum time slot time, if there is a node at the coordinate position “B2”, the presence of the node distribution in FIG. 10A is present. Since the node performs time adjustment by adjusting timing with all nine nodes including its own node, it is difficult to execute time slot assignment. If the number of nodes in the reachable range of this node is reduced, it becomes easier to adjust timing.

  In such a case, for each of the other nodes within the reach of the coordinate position “B2” (may be all or a part designated by the operator), only that one other node Simulates the reach in the state where the output is lowered (lower by one if the output stage is several stages), and selects the optimum node for adjusting the output. Here, the optimal node is a node in which the distribution of the number of receiving nodes becomes the most uniform by lowering the output.

  In the case where the simulation unit 25 determines the optimum node, for example, the variance of the number of received nodes at the coordinate position belonging to the predetermined area centered on the coordinate position or the coordinate position to be reduced is minimized. Then, it is only necessary to determine the other node that provides the adjustment result (the distribution of the number of received nodes). If the operator is to select a candidate node for output adjustment, the simulation unit 25 may select from other nodes having a large number of neighboring nodes (the number of receiving nodes) or from other nodes having a wide reach. .

  In the case where the simulation unit 25 instructs the operator to specify the number of steps to decrease the output, adjustment candidates, and the like, the simulation unit 25 performs a display requesting an instruction from the display device 13, and the worker responds accordingly by the input device 14. You can import the contents entered for.

  FIG. 10B shows an example in which the number of nodes in the reach range is reduced by adjusting the transmission output of the nodes around the coordinate position “B2”, and the coordinate position “D4” becomes the adjustment node. This is an example. When there is a node at the coordinate position “D4” and the transmission output of this node is lowered, the estimated value of the number of reception nodes for each coordinate becomes a distribution as shown in FIG. For example, an approximate form in which the reach range before adjusting transmission power (a boundary curve defining the transmit power) is reduced by a predetermined ratio is set as the reach range after adjustment.

  The distribution after adjustment is a coordinate that is within the reach of the coordinate position (for example, “D4”) of the adjustment center in the distribution before adjustment (see FIG. 10A), and no longer belongs to the reach after adjustment. The number of receiving nodes at the coordinate position is reduced by one from before the adjustment, and the number of receiving nodes at the coordinate position outside the reaching range before the adjustment and within the reaching range after the adjustment is increased by one from before the adjustment. The number of reception nodes at the coordinate position within the reach range both before and after, and the number of receive nodes at the coordinate position outside the reach range both before and after the adjustment are formed by maintaining the number of reception nodes before the adjustment as it is.

  For example, by adjusting the output of the coordinate position “D4”, the coordinate position “B2” falls outside the reachable range of the node at the coordinate position “D4”, and the number of neighboring nodes at the coordinate position “B2” decreases.

  In practice, when the transmission output power of the node at the coordinate position “D4” is lowered and the number of neighboring nodes at the coordinate position “B2” does not change, for example, the node at the coordinate position “D4” is again displayed. Decrease the transmission output or reduce the transmission output of other nodes within the reach range of the coordinate position “B2”.

  Although not shown here, it is preferable that the packet analyzer 12 can instruct the node N to change the transmission output power via the packet capture device 11.

  Further, the problem relating to the time slot period for a node having a large number of other nodes (number of receiving nodes) in the reachable range can be solved by changing the installation position of the node (moving the node).

  When trying to reduce the number of other nodes in the reach by changing the installation position of the node, the simulation unit 25 calculates to which position the node should be moved. For example, for the node at the coordinate position “B2” as shown in FIG. 10A, the simulation unit 25 selects one of the coordinates “7” having the smallest number of neighboring nodes among the surrounding coordinates within the reachable range. Decide to move. The coordinate of “7” having the smallest number of neighboring nodes may be determined by presenting the distribution of the number of receiving nodes at each destination candidate and allowing the operator to select the coordinates. The coordinate position where the distribution is most uniform may be automatically determined. FIG. 12 is a distribution of the number of received nodes for each coordinate when the node at the coordinate position “B2” is moved to the coordinate position “C2”.

  The distribution after the movement is a coordinate within the reach of the node at the coordinate position “B2” in the distribution before the movement (see FIG. 10A), and the arrival range centered on the coordinate position “C2” after the movement. The number of receiving nodes at a coordinate position that no longer belongs to is less by 1 than before the movement, and the number of receiving nodes at a coordinate position outside the reaching range before the movement and within the reaching range after the movement is 1 before the movement. The number of received nodes at the coordinate position within the reach range before and after the movement and the number of receive nodes at the coordinate position outside the reach range both before and after the move are formed by maintaining the number of receive nodes before the move as it is. .

  If it is found by simulation of this movement that all surrounding nodes can secure a period longer than the minimum time slot period (if the number of receiving nodes at the coordinate position where each node is located is 8 or less), Decide to actually move.

  In addition, even if the result of the movement simulation shows that there is a node that cannot secure the minimum time slot period (including not only the case where the minimum time slot period is not possible from the beginning, but also a case where the node newly appears as a result of movement) Perform more simulations.

  The network state is optimized while referring to the actual analysis result while predicting the optimum network state using the various simulations as described above.

(A-4) Effect of First Embodiment According to the first embodiment, each node transmits a packet including neighboring node information of its own node, and a packet analyzer collects such a packet. Since the reach of the packet (radio wave) from the node and the node density (the number of received nodes at each coordinate position) are analyzed, the performance and failure status of the wireless network can be detected almost in real time.

  In addition, the network state estimation function after changing the node state (position and transmission output power) is provided, so even if the node is installed in a wide range, optimal node installation design and failure avoidance measures can be taken. You can do it quickly.

(B) Second Embodiment Next, a second embodiment of the network analysis system and method according to the present invention will be described in detail with reference to the drawings. Hereinafter, differences from the above-described first embodiment will be described.

  In the first embodiment described above, the case where the position of each node and the radio wave arrival range (output power from the node) can be registered in the packet analyzer 12 in advance has been described. In the second embodiment, Regarding the case where the position and radio wave reach of each node cannot be registered in the packet analyzer 12 in advance, the radio wave reach and node position of each node are estimated and analyzed.

  Also in the second embodiment, the configuration of the wireless network to be analyzed, the configuration of the network analysis system, and the like can be represented by FIG. 1, and the internal configuration of the packet analyzer 12 can also be represented by FIG.

  In the second embodiment, an identifier is assigned to each packet capture device 11. In the packet analyzer 12, the identifier and position of each packet capture device 11 are associated in advance.

  In the case of the second embodiment, each packet capture device 11 has a function of measuring the electric field strength of the received packet. From the packet capture device 11 to the packet analyzer 12, the identifier of the packet capture device 11 and the electric field strength are also input together with the received packet.

  In the case of the second embodiment, as shown in FIG. 13, the node information table 26 includes a packet capture device 11-i that can receive a packet transmitted by a node and a received electric field strength ( For example, it is configured such that at least one or more average values of actually measured values can be referred to.

  FIG. 14 is a flowchart illustrating an operation for estimating a radio wave arrival range in the second embodiment.

  When the packet capture device 11 receives the packet, the packet is input to the packet analyzer 12, and the packet analyzer 12 determines whether the packet is an analysis target packet (S31, S32).

  If it is not an analysis target packet, the process proceeds to step S37 described later. If it is an analysis target packet, the corresponding row of the node information table 26 is searched, and the identifier and field strength of the packet capture device 11-i are described (S33). .

In the node information table 26 of FIG. 13, up to three sets of identifiers and field strengths of the packet capture device 11 can be described, but the packet capture device 11 at the fourth location can receive packets from the same transmission source node. If received, the information with the lowest electric field strength is deleted. The node information table 26 may describe four or more sets of identifiers and field strengths of the packet capture device 11.

  Next, the position of the transmission source node of the packet is calculated using the identifiers and electric field strength information of the plurality of sets of packet capture devices 11 in the node information table 26 (S34). A method for estimating the position of the transmission source from the received electric field intensity at a predetermined position is described in, for example, a reference document “Oki Technical Review No. 204, Vol. 72, No. 4, pp 24-27”. It is assumed that the received electric field intensity and the distance have a relationship as shown in FIG. If the field strengths at the three packet capture devices are RA, RB, and RC, these field strength information RA, RB, and RC are converted into distances dA, dB, and dC, and each packet whose position is known is converted. The same points that are separated from the capture device by distances dA, dB, and dC are estimated as the positions of the transmission source nodes. This estimation process may be executed only once if the node installation position is fixed.

  The method of estimating the position of the transmission source node is not limited to the method described above. For example, the distance is estimated using the reception time difference between two packet capture devices, and a plurality of such distance information is obtained by changing the combination of the two packet capture devices to estimate the position of the transmission source node. You may make it do.

  Next, the radio wave reachable range is estimated (S35). As the estimation method, any existing method may be applied.

  For example, there is a method using a signal between nodes. In the technique described in Patent Document 1, a node that has received a communication timing control signal transfers the communication timing control signal. Therefore, a node that transfers a communication timing control signal within a predetermined time with respect to a certain communication timing control signal is a node that is within the radio wave reach of the original node.

  In the example illustrated in FIG. 16, after the node N1 transmits the communication timing control signal, the nodes N2, N3, and N6 transfer and transmit the communication timing control signal within a predetermined time Δt. Thus, a range including the three nodes N2, N3, and N6 is set as a radio wave reachable range of the node N1. In such a case, the control packet includes a node address that has been transferred, and information that can distinguish between the packet before transfer and the transferred packet, and the packet analyzer 12 is given by the packet capture device 11. The radio wave reach from each node is estimated based on the packet to which the reception time information is added.

  Further, the distance corresponding to the carrier sense level CL, which is the minimum level for certifying the presence of the carrier shown in FIG. 15, may be set as the limit distance of the radio wave reachable range.

  After estimating the radio wave reachable range, display control similar to that in the case of the first embodiment (S24 to S26 in FIG. 7) is performed (S36 to S38).

(B-3) Effects of Second Embodiment Also according to the second embodiment, the same effects as those of the first embodiment can be obtained, and further, the following effects can be obtained.

  By capturing packets at multiple points and estimating the location of the source node of the packet and the radio wave arrival range, the node does not have a special reception function, and without registering information in advance via an input device The node position and radio wave reach can be grasped and displayed.

  In addition, when a method in which a packet analyzer analyzes whether a response to a signal transmitted by a certain node is transmitted or not and determines a reception range (radio wave reachable range), each node is in communication range of its own node. Can be determined without generating a packet for notifying the surroundings of the signal, the signal packet size can be reduced, and the node can be simplified.

  Furthermore, since it is not necessary to register the node installation position in the packet analyzer in advance, even when the node moves, it can be easily associated with the actual position.

(C) Other Embodiments In the above embodiments, when the number of receiving nodes is larger than the number of threshold nodes considering the minimum time slot period, the network configuration is reviewed using the simulation function of the packet analyzer 12 However, the network configuration may be reviewed based on other criteria. For example, when the radio wave reachable range that can be calculated from the transmission output power is different from the actually measured radio wave reachable range, the network configuration may be reviewed so that both ranges are close to each other.

  In the second embodiment, the received electric field strength used for estimating the position of the transmission source node is only shown in the packet capture device, but the received electric field strength in each node inserted in the analysis target packet is also shown. It may be used.

  In each of the above-described embodiments, the radio wave reachable range is displayed and output at normal times. However, the number of receiving nodes at each coordinate position may be displayed at normal times by the operator's selection or the like. The output method is not limited to display output, and may be another method such as print output, or a combination of a plurality of output methods.

1 is a block diagram showing a schematic configuration of a network analysis system and an analysis target wireless network according to a first embodiment. It is a block diagram which shows the functional structure of the packet analyzer which concerns on 1st Embodiment. It is explanatory drawing which shows the structure of the analysis object packet in 1st Embodiment. It is explanatory drawing which shows the structure of the node information table in 1st Embodiment. It is explanatory drawing of the principle of the communication timing calculation method in each node of 1st Embodiment. It is a flowchart which shows creation and update operation | movement of the node information table in 1st Embodiment. It is a flowchart which shows the analysis of the communication timing and reach | attainment range, and display processing in 1st Embodiment. It is explanatory drawing which shows the example of a display of the analysis result of the packet analyzer in 1st Embodiment (the 1). It is explanatory drawing which shows the example of a display of the analysis result of the packet analyzer in 1st Embodiment (the 2). It is explanatory drawing which shows the example of a display of the analysis result of the receiving node number distribution by the packet analyzer in 1st Embodiment. It is explanatory drawing of the example of an estimation method of the number of nodes of the transmission source which can receive the packet in the arbitrary positions in 1st Embodiment. It is explanatory drawing which shows the example of an estimation result of distribution of the number of receiving nodes after the position change of the node in 1st Embodiment. It is explanatory drawing which shows the structure of the node information table in 2nd Embodiment. It is a flowchart which shows the estimation operation | movement of the electromagnetic wave range in 2nd Embodiment. It is explanatory drawing of the position estimation method of the transmission source node in 2nd Embodiment. It is explanatory drawing of the estimation method of the electromagnetic wave arrival range from the transmission source node in 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Network analysis system, 11-1 to 11-4 ... Packet capture apparatus, 12 ... Packet analyzer, 13 ... Display apparatus, 14 ... Input device, 21 ... Packet analysis part, 22 ... Node information update part, 23 ... Reaching range Calculation unit, 24 ... display control unit, 25 ... simulation unit, 26 ... node information table, N1 to N20 ... node.

Claims (5)

Network analysis for analyzing a wireless network composed of a plurality of nodes having communication timing control means for autonomously determining a time slot capable of transmitting a data signal from the own node based on transmission / reception of communication timing control signals between nodes In the system,
Having one or more packet capture devices and packet analyzers;
Each of the nodes transmits the communication timing control signal including the source node address, the number of neighboring nodes located in the vicinity of the node, and the neighboring node address,
Each packet capture device intercepts the communication timing control signal on the wireless network and sends intercept information to the packet analyzer,
The above packet analyzer
For each of the above nodes, node information storage means for storing reception range information including information of neighboring nodes that have transmitted the communication timing control signal that the local node has received,
Based on the number of neighboring nodes and the neighboring node address of the intercepted communication timing control signal , the reception range information stored in the node information storage means for the transmission source node of the communications timing control signal intercepted by the packet capture device. and information updating means for updating Te,
Output information forming means for forming output information from information stored in the node information storage means;
A network analysis system comprising: output means for outputting the formed output information.   The network analysis system according to claim 1, wherein the output information is a radio wave reachable range related to a communication timing control signal from a transmission source node.   The network analysis system according to claim 1 or 2, wherein the output information is the number of transmission source nodes that can be estimated to receive a communication timing control signal at each position in a communication area of a wireless network.   The said output information formation means has a function which forms the said output information at the time of assuming that the state of each said node was changed based on the output information before the said assumption. The network analysis system according to any one of the above. Network analysis for analyzing a wireless network composed of a plurality of nodes having communication timing control means for autonomously determining a time slot capable of transmitting a data signal from the own node based on transmission / reception of communication timing control signals between nodes In the method
Together with one or more packet capturing device and a packet analyzer, the packet analyzer includes a node information memory means, information updating means, the output information forming means and output means,
Each packet capture device intercepts the communication timing control signal on the wireless network and sends intercept information to the packet analyzer,
The node information storage means stores, for each of the nodes, reception range information including information on neighboring nodes that have transmitted the communication timing control signal that the node has received,
The information update means includes the reception range information stored in the node information storage means related to the source node of the communication timing control signal intercepted by the packet capture device , and the number of neighboring nodes of the intercepted communication timing control signal. And updating based on neighboring node addresses ,
The output information forming means forms output information from information stored in the node information storage means,
A network analysis method characterized by outputting the output information formed by the output means.

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