JP4862692B2 - Wireless communication control device, node and wireless system - Google Patents

Description

  The present invention relates to a radio communication control device, a node, and a radio system. For example, in a radio system composed of a plurality of radio nodes, communication control of a transmission signal of a position estimation system for detecting the position of a specific radio node is performed. The present invention can be applied to a wireless communication control device, a node, and a wireless system.

  For example, if you want to know the position of a specific object, or if you want to know the presence or absence of a specific object from a remote location, attach a wireless communication device to the specific object and use this wireless communication device to There is a technique for estimating the position of. As this position estimation technique, for example, there is a technique for estimating the position of a wireless communication device using GPS (Global Positioning System) or PHS (Personal Handyphone System).

  However, these systems need to receive radio waves from multiple satellites and base stations, so they are suitable for outdoor and wide space use, but may not be applicable for indoor use. .

  Conventionally, as a position estimation technique used indoors, for example, there is a method of estimating the position of an object based on the received power intensity (hereinafter also referred to as a received power value) of a received radio wave (Non-patent Document 1 and Patents). Reference 1). In general, the received power intensity of radio waves uses a characteristic that is inversely proportional to the distance, and by estimating the distance from the received power value, the distance between a plurality of wireless communication devices is measured and the position of the object is estimated. That's it.

  For example, when estimating the position of a mobile node using a fixed node whose position is known in advance, the following two types of methods are mainly conceivable.

  The first is a method when a mobile node transmits measurement signals to a plurality of fixed nodes. In this case, each fixed node measures the received power value of the measurement signal from the mobile node, and returns the measured received power value on the reply signal to the mobile node. Then, the mobile node estimates the position of its own node using the received power values from the plurality of fixed nodes and the positions of the respective fixed nodes. Note that it is also possible to collect received power measurement results at a specific fixed node and perform calculation processing of position estimation at the specific fixed node.

  The second is a method when a fixed node periodically sends a measurement signal. In this case, the mobile node measures received power values of measurement signals from a plurality of fixed nodes, and estimates the position of the own node using these received power values and the positions of the fixed nodes.

JP 2005-507070 A "Indoor location estimation system using IEEE802.15.4", IEICE, 3rd Sensor Network Study Group, January 2006

  However, in the first position estimation method described above, the fixed node that has measured the received power value of the measurement signal needs to notify the mobile node of the received power value. Therefore, when multiple fixed nodes transmit at the same time at the same time, there is a possibility that frames from multiple fixed nodes may collide with each other, and as a result, collected measurement results of received power values necessary for position estimation at the mobile node It may not be possible, and the position estimation of the own node may not be accurately calculated.

  Here, the measurement result of the received power value transmitted by the fixed node may include a measurement result that is not important for the calculation of position estimation, for example, the received power value is too small. Therefore, transmission of such an unimportant measurement result is not desirable from the viewpoint of effective use of the radio band, and is also not desirable from the viewpoint of redundant collection of important measurement results due to collision with other frames.

  In the second position measurement method described above, the fixed node needs to transmit a measurement signal periodically. In this case as well, if a plurality of fixed nodes transmit measurement signals at the same time at the same time, the frames (measurement signals) may collide with each other, and the position estimation of the own node may not be accurately calculated. It can happen.

  Note that not only in the position estimation system but also in other wireless communication systems, frame reception may not be performed properly due to frame collision.

  Therefore, in order to avoid frame collision, a wireless communication control device, a node, and a wireless system that can transmit a transmission signal at an appropriate transmission timing are required.

  In order to solve such a problem, the radio communication control apparatus according to the first aspect of the present invention (1) receives a radio signal transmitted by a mobile node constituting a radio system, and one or a plurality of other nodes are connected to the mobile node. Receiving means for receiving a radio signal to be transmitted to the mobile node; (2) transmitting means for transmitting a transmission signal to the mobile node; and (3) a reception result of the radio signal from each other node and radio from the mobile node. Communication control means for controlling the transmission timing of the transmission signal according to the positional relationship result with the mobile node including each other node obtained based on the signal reception result is provided.

  A node according to a second aspect of the present invention is a node that transmits a radio signal toward a mobile node constituting a wireless system, and includes the communication control apparatus according to the first aspect of the present invention.

  The radio system according to the third aspect of the present invention includes a mobile node and a plurality of nodes according to the second aspect of the present invention.

  According to the present invention, it is possible to transmit a transmission signal at an appropriate transmission timing in order to avoid frame collision.

(A) First Embodiment Hereinafter, a first embodiment of a wireless communication control device, a node, and a wireless system of the present invention will be described in detail with reference to the drawings.

  For example, the first embodiment is applied to a position estimation system that estimates the position of a certain wireless communication device in a wireless network system configured by a plurality of wireless communication devices adopting the IEEE 802.15.4 standard. Will be described.

(A-1) Configuration of First Embodiment FIG. 2 is a configuration diagram illustrating a configuration example of a wireless network system according to the first embodiment. In FIG. 2, a wireless network system 200 includes a mobile node 201 that is a position estimation target, fixed nodes 203 to 208 to which its own accurate position information is input in advance, and a fixed node function, for example, the Internet. And a gateway node 202 having a connection function with an external network 210 such as an intra network.

  When the fixed nodes 203 to 208 and the gateway 202 receive the received power measurement signal transmitted from the mobile node 201 that is the position estimation target, the fixed nodes 203 to 208 measure the received power value of the measurement signal, and send a reply signal including the measurement result. This is a reply to the mobile node 201.

  When the fixed nodes 203 to 208 and the gateway 202 receive the return signal transmitted from another fixed node, the received power value of the return signal from the other fixed node is measured, and the return signal from the other fixed node is measured. Is compared with the received power value of the measurement signal measured at the own node, and the transmission timing of the reply signal returned to the mobile node 201 is controlled according to the comparison result.

  FIG. 1 is a functional block diagram illustrating an internal configuration of the fixed node 100 (203 to 208) according to the first embodiment. In FIG. 1, a fixed node 100 according to the first embodiment includes a radio reception processing unit 101, a reception power measurement unit 102, a header detection unit 103, a reply signal generation unit 104, a data reading unit 105, a buffer unit 106, and a transmission control unit. 107 and a wireless transmission processing unit 108.

  The radio reception processing unit 101 performs predetermined demodulation processing and frequency conversion processing on the received radio signal, extracts a predetermined frame from the radio signal, and provides the predetermined frame to the header detection unit 103.

  The received power measuring unit 102 measures the received electric field strength based on reception of an incoming radio signal, and obtains a received power value based on the received electric field strength.

  The header detection unit 103 detects address information such as a transmission destination address and a transmission source address, an identifier indicating the type of the frame, and the like from the predetermined frame extracted by the wireless reception processing unit 101.

  The reply signal generation unit 104 receives the radio signal measured by the reception power measurement unit 102 when the transmission source address of the received frame is the address of the mobile node 201 and the frame type is a measurement signal of reception power. The received power value measurement result and the position information of the own node 100 are inserted into the data part of the frame to generate a reply signal.

  The buffer unit 106 temporarily holds the reply signal generated by the reply signal generation unit 104.

  The data reading unit 105 is included in the data part of the frame when the transmission source address of the received frame is an address of another fixed node and the frame type is a return signal of the reception power measurement result. The received power value is read out.

  The transmission control unit 107 controls the timing for transmitting the return frame of the measurement result held in the buffer unit 106 based on the received power value of the measurement result at the other fixed node read by the data reading unit 105. It is.

  Further, the transmission control unit 107 includes a counter unit 107a that counts the number of received return signals from other fixed nodes for each mobile node.

  Furthermore, the transmission control unit 107 is for setting the buffer holding time of the return signal held in the buffer unit 106, and compares the received power value at the other fixed node with the received power value at the own node. A timer unit 107b that can change the timer value according to the result is provided.

Further, the transmission control unit 107 measures the number of return signals from other fixed nodes addressed to the mobile node 201 that transmitted the measurement signal. The transmission processing unit 108 performs frequency conversion or predetermined modulation on the frame to be transmitted. It performs processing and transmits it as a radio signal.

  In FIG. 1, the buffer unit 106 and the transmission control unit 107 are provided with a plurality of processing functions. Thereby, a plurality of processes can be executed in parallel, and the positions of the plurality of mobile nodes 201 can be estimated simultaneously. Of course, each may have one processing function.

  Next, the mobile node 201 will be described. The mobile node 201 transmits a measurement signal for measuring the received power when estimating the position of its own node. In addition, the mobile node 201 receives a return signal including the received power value from the fixed nodes 203 to 208 and the gateway 202, and estimates the position of the own node based on the received power value.

  FIG. 3 is a functional block diagram showing the internal configuration of the mobile node 201. In FIG. 3, the mobile node 201 includes at least a reception processing unit 301, a header detection unit 302, a data reading unit 303, a buffer unit 304, a position estimation processing unit 305, a measurement signal generation unit 306, and a transmission processing unit 307.

  The measurement signal generation unit 306 generates a measurement signal for measuring received power when the position of the own node is to be estimated, and gives the generated measurement signal to the transmission processing unit 307.

  When receiving the measurement signal from the measurement signal generation unit 306, the transmission processing unit 307 performs frequency conversion processing and predetermined modulation processing on the measurement signal, and transmits the measurement signal as a radio signal. The transmission processing unit 307 serves not only for the measurement signal transmission process, but also for the transmission process for all transmission signals transmitted by the mobile node 201.

  The reception processing unit 301 performs predetermined demodulation processing and frequency conversion processing on the received radio signal, extracts a predetermined frame from the radio signal, and provides the predetermined frame to the header detection unit 302.

  The header detection unit 302 receives a frame from the reception processing unit 301, and detects address information such as a transmission source address and a transmission destination address, an identifier indicating the type of the frame, and the like from the frame.

  The data reading unit 303 is included in the data part of the frame when the transmission source of the received frame is an address of a fixed node and the frame type is a return signal of the measurement result of the received power value of the measurement signal. The measurement result of the received power value of the measurement signal is read and given to the buffer unit 304.

  The buffer unit 304 temporarily stores the measurement result of the received power value of the measurement signal at the plurality of fixed nodes and the position information of each fixed node read by the data reading unit 303.

  The position estimation processing unit 305 estimates the position of the own node 201 based on the received power values of the measurement signals at a plurality of fixed nodes and the position information of each fixed node held by the buffer unit 304. . As a method of position estimation processing by the position estimation processing unit 305, an existing technique can be applied, and detailed description thereof is omitted here.

  In the first embodiment, the functions of the fixed node and the mobile node are distinguished for the sake of convenience of explanation. However, the respective feature functions may be provided redundantly and may be operated as any node. In addition, each function indicates a case where a hardware resource (for example, a configuration of an arithmetic device such as a general-purpose processor or a storage device such as a memory or a disk) is a software process realized by executing a processing program. However, it may be realized by hardware.

(A-2) Operation of the First Embodiment Next, the operation of the frame transmission control process in the position estimation system of the first embodiment will be described in detail with reference to the drawings.

  FIG. 4 is a flowchart showing an operation of frame transmission control processing in the fixed node 100.

  First, when the position estimation of the mobile node 201 is started, a measurement signal is generated by the measurement signal generation unit 306 in the mobile node 201, and the measurement signal is transmitted. The measurement signal transmitted from the mobile node 201 is received by the fixed nodes 203 to 208 and the gateway 202 existing in the vicinity of the mobile node 201, and the processing shown in FIG. 4 is performed in the fixed nodes 203 to 208 and the gateway 202 that have received the measurement signal. Is done.

  When the wireless signal is received by the fixed node 100, the wireless reception processing unit 101 performs predetermined demodulation processing, frequency conversion processing, and the like, and extracts a predetermined frame (S401).

The header detection unit 103 detects the type of the extracted frame, address information, and the like, and determines whether the extracted frame is a measurement signal from the mobile node 201 or a return signal from another fixed node. (S402, S403)
When the header detection unit 103 determines that the signal is neither a measurement signal nor a reply signal, the frame is discarded (S404).

  If it is determined in S402 that the received frame is a measurement signal, the transmission control unit 107 measures the number of return signals from other fixed nodes destined for the mobile node 201 that has transmitted the measurement signal. Is initialized (S405).

  Further, the received power measuring unit 102 measures the received power intensity of the radio signal of the measurement signal, and the received power value as the measurement result is given to the return signal generating unit 104. In the reply signal generation unit 104, the received power value of the measurement signal and the position information of the own node 100 are inserted into the data part of the frame, and a reply signal is generated (S406).

  When the reply signal is generated, the buffer holding time for holding the reply signal is set according to the value indicated by the timer unit 107b (S407), and the reply signal is temporarily held in the buffer unit 106 until the buffer holding time elapses. (S408, S409). The setting of the value indicated by the timer unit 107b will be described later.

  When the buffer holding time elapses, the reply signal held in the buffer unit 106 is read from the transmission control unit 107 (S408, S409).

  On the other hand, if it is determined in S403 that the received frame is a reply signal from another fixed node, the transmission signal is transmitted from another fixed node for each destination of the reply signal (that is, for each mobile node that transmitted the measurement signal). The count value of the counter 107a that measures the number of received reply signals is added (S410).

  Next, the frame of the reply signal is given to the data reading unit 105, and the received power value of the measurement signal measured at another fixed node is read from the data unit of the frame (S411).

  Then, for each mobile node that has transmitted the measurement signal, the transmission control unit 107 compares the received power value of the measurement signal measured by the own node 100 with the received power value measured by another fixed node (S412). .

  As a result, when the received power value measured at the other fixed node is larger than the received power value measured at the own node 100, the timer value of the timer unit 107b is added by the transmission control unit 107 (S413). As a result, the buffer holding time of the reply signal can be extended, so that the fixed signal other than the own node can transmit the reply signal first. This is because it can be determined that the reply signal from another fixed node has higher priority for the mobile node 201 than the reply signal from the own node.

  On the other hand, when the received power value measured at the other fixed node is equal to or smaller than the received power value measured at the own node, the timer value of the timer unit 107b is subtracted by the transmission control unit 107 (S414). Thereby, the buffer holding time of the reply signal can be shortened, so that the own node can transmit the reply signal earlier than the other fixed nodes. This is because it can be determined that the reply signal from the own node has higher priority for the mobile node 201 than the reply signals from other fixed nodes.

  Thus, the transmission timing of the return signal from each fixed node 100 to the mobile node 201 can be adjusted autonomously in each fixed node 100. As a result, when the received power value measured by the own node 100 is higher than that of other fixed nodes, the transmission timing is advanced (that is, the priority is high), and the received power value measured by the own node is set to another fixed value. If it is smaller than that of the node, the transmission timing is delayed (that is, the priority is low), so that the mobile node 201 always receives a reply signal including a measurement result having a large reception power value preferentially. . In addition, since the transmission timing of the reply signal is adjusted autonomously between the fixed nodes, it is possible to avoid frame collision between the reply signals.

  Note that the range in which the timer value of the timer unit 107b is added and subtracted may be a constant value or a variable value. In the case of the variable value, for example, the addition width and the subtraction width are adjusted to increase as the difference between the reception power value at the own node and the reception power value at another fixed node increases. In this case, the variable value may be obtained by a predetermined arithmetic expression, or the variable value may be obtained by using a preset correspondence table between the difference between the received power values and the variable value. May be.

  Subsequently, when the count value of the counter 107a is equal to or less than the prescribed number of transmissions (S415), the reply signal held in the buffer unit 106 is transmitted as a radio signal by the radio transmission processing unit 108.

  On the other hand, when the counter value of the counter 107a is larger than the prescribed transmission number (S415), the frame of the reply signal is discarded (S404), and the reply signal is not transmitted as a radio signal. As a result, it is possible to prevent the mobile node 201 from transmitting redundant reply signals that have already exceeded the prescribed number of transmissions.

  Here, the prescribed number of transmissions is the number of transmissions of return signals necessary for the mobile node 201 to perform position estimation. In general, the position can be estimated if at least three reply signals are received, and it is desirable to set a numerical value corresponding to the estimated position.

(A-3) Effect of First Embodiment As described above, according to the first embodiment, the transmission timing of the return signal can be adjusted according to the magnitude of the received power value of the measurement signal. Therefore, frame collision can be avoided, and the mobile node 201 can preferentially receive a reply signal having a large received power value of the measurement signal, and efficiently collect data necessary for position estimation calculation. Can do.

  Further, according to the first embodiment, since the mobile node 201 is not transmitted with a redundant reply signal using the specified number of transmissions, the utilization efficiency of the radio band can be improved.

(B) Second Embodiment Next, a second embodiment of the wireless communication control device, node, and wireless system of the present invention will be described in detail with reference to the drawings.

  The second embodiment is also an example in which the second embodiment is applied to a position estimation system that estimates the position of a certain wireless communication device in a wireless network system configured by a plurality of wireless communication devices adopting the IEEE 802.15.4 standard. Will be described.

  The second embodiment is based on the assumption that a fixed node periodically transmits a measurement signal, and a mobile node that has received the measurement signal returns a reply signal.

(B-1) Configuration of Second Embodiment FIG. 5 is a functional block diagram illustrating an internal configuration of a fixed node according to the second embodiment. In FIG. 5, the fixed node 500 according to the second embodiment includes a radio reception processing unit 501, a reception power measurement unit 502, a header detection unit 503, a measurement signal generation unit 504, a buffer unit 506, a transmission control unit 507, and a radio transmission process. Part 508 at least.

  The configuration of the fixed node 500 of the second embodiment is different from the configuration of the first embodiment in that the measurement signal generation unit 504 is provided instead of the reply signal generation unit 104 and the data reading unit 105 is not provided. Is a point.

  The measurement signal generation unit 504 periodically generates a measurement signal to be transmitted to the mobile node 201, and gives the generated measurement signal to the buffer unit 506.

  FIG. 6 is a functional block diagram illustrating an internal configuration of the mobile node according to the second embodiment. 6, the mobile node 600 of the second embodiment includes a reception processing unit 601, a header detection unit 602, a data reading unit 603, a buffer unit 604, a position estimation processing unit 605, a reply signal generation unit 606, and a transmission processing unit 607. At least.

  The configuration of the mobile node 600 of the second embodiment is different from the configuration of the first embodiment in that a reply signal generation unit 606 is provided instead of the measurement signal generation unit 306.

  The reply signal generation unit 606 inserts the result of position estimation processing by the position estimation processing unit 605 into the data part and generates a reply signal.

(B-2) Operation of Second Embodiment Subsequently, the operation of the frame transmission process in the position estimation system of the second embodiment will be described in detail with reference to the drawings.

  FIG. 7 is a flowchart showing the operation of frame transmission processing in the fixed node 500.

  The following signal transmission / reception sequence is based on the assumption that a fixed node periodically transmits a measurement signal, and a mobile node that has received the measurement signal transmits a reply signal.

  First, in the fixed node 500, a measurement signal is periodically generated by the measurement signal generation unit 504 (S701), a buffer holding time of the measurement signal is set according to the timer value of the timer unit 507b (S702), and the generated measurement is performed. The signal is held in the buffer unit 506 (S703).

  On the other hand, when a radio signal arrives, the radio signal is received by the radio reception processing unit 501, and predetermined demodulation processing, frequency conversion processing, and the like are performed, and a frame is extracted (S704). At this time, the received power value of the radio signal is measured by the received power measuring unit 502 (S705).

  For the received frame, the header detection unit 503 identifies the frame transmission destination, the address information of the transmission source, the frame type, and the like, and whether the frame is a measurement signal transmitted by another fixed node or the mobile node 201. Is a transmitted reply signal (S706, S707).

  If the frame is neither a measurement signal nor a reply signal, the frame is discarded (S708). This is because it is determined that this frame is not necessary for position estimation.

  In S706 and S707, when the received frame is a measurement signal and a reply signal, the received frame is temporarily held in the buffer unit 506, and the received power value of the measurement signal transmitted by another fixed node for the same mobile node. The transmission control unit 507 compares the received power value of the reply signal transmitted by the mobile node 201 (S709).

  As a result of comparison by the transmission control unit 507, when the received power value of the measurement signal transmitted by another fixed node is larger than the received power value of the return signal transmitted by the mobile node, the mobile node 201 is viewed from the own node 500. Is determined to be located farther than other fixed nodes, the timer value of the timer unit 507b is added (S710), and the buffer holding time of the measurement signal is lengthened.

  As a result, the transmission cycle of the measurement signal transmitted by the own node 500 is lengthened, and the frequency of transmission of the measurement signal that is redundant for the mobile node 201 is decreased.

  On the other hand, when the received power value of the measurement signal transmitted by another fixed node is equal to or less than the received power value of the return signal transmitted by the mobile node, the mobile node 201 is more than the other fixed node as viewed from the own node 500. Therefore, the timer value of the timer unit 507b is subtracted (S711), and the buffer holding time of the measurement signal is shortened.

  Thereby, the transmission cycle of the measurement signal transmitted from the own node 500 is shortened, and the frequency of transmission of the measurement signal necessary for the mobile node 201 is increased.

  The measurement signal held in the buffer unit 506 is read by the transmission control unit 507 and transmitted by the wireless transmission processing unit 508 after the buffer holding time has elapsed (S712, S713).

  By adjusting the transmission timing of the measurement signal of the fixed node 500 as described above, the mobile node 201 can preferentially receive the measurement signal from the fixed node 500 that seems to be close to the mobile node 201. it can.

(B-3) Effect of Second Embodiment As described above, according to the second embodiment, the transmission period of the measurement signal from the fixed node close to the mobile node is shortened, and the fixed node far from the mobile node is used. By increasing the transmission period of the measurement signal, it is possible to efficiently collect data required for position estimation.

  Further, according to the second embodiment, the use efficiency of the radio band can be improved by shortening the transmission cycle of the redundant measurement signal.

(C) Other Embodiments (C-1) In the first embodiment, the transmission timing of the reply signal transmitted from the own node is adjusted based on the received power value included in the reply signal from another fixed node. However, a value proportional to the reciprocal value of the received power value of the measurement signal transmitted by the mobile node 201 may be set as the transmission interval of the return signal.

  Thereby, when the reception power value of the measurement signal from the mobile node 201 is large, the transmission interval of the reply signal at the own node 100 can be set short, and when the reception power value is small, at the own node 100 Since the transmission interval of the return signal can be set longer, the same effect as that of the first embodiment can be obtained.

  In this case, the transmission control unit 107 includes a calculation unit that reverses the reception power value of the return signal of another fixed node measured by the reception power measurement unit 102. Furthermore, the transmission control unit 107 sets the transmission interval based on the calculation result, that is, the reciprocal value of the reception power value of the return signal of another fixed node, or a value proportional to the reciprocal value. It is necessary to provide a setting unit.

(C-2) In the second embodiment, the received power value of the return signal from the mobile node 201 and the received power value of the measurement signal from the other fixed node are measured, and the positional relationship with the other fixed node is determined. Although the case of estimating and adjusting the buffer holding time has been described, the present invention is not limited to this, and other methods may be applied.

  For example, the fixed node reads the value of the position information estimated by the mobile node, the fixed node information used for position estimation, etc. included in the data part of the reply signal from the mobile node, and based on these information The buffer holding time may be adjusted.

  As a specific example, for example, the position information estimated by the mobile node is compared with the position information of another fixed node. If the position of the own node is closer to the mobile node, the buffer holding time is shortened, If the node is closer to the mobile node, the buffer holding time is lengthened, so that a fixed node near the mobile node can actively transmit the measurement signal.

  In this case, the mobile node inserts the received power measurement unit for measuring the received power value of the measurement signal from the fixed node, the position estimation result based on the measurement result, and the fixed node information used for position estimation into the reply signal. It is necessary to provide transmission means for transmitting a reply signal.

  In addition, the fixed node includes a data reading unit (data extraction unit) that reads position estimation information included in a reply signal from the mobile node and fixed node information used for position estimation. Further, the transmission control unit of the fixed node estimates the mutual positional relationship between the position information of the own node, the position information of the mobile node, and the position information of the fixed node used by the mobile node for position estimation, and sets the buffer holding time. A transmission timing adjustment unit for adjustment is provided.

(C-3) In the first and second embodiments, a case where the mobile node is applied to a position estimation system that performs position estimation processing has been described. For example, a system in which a fixed node performs position estimation processing of a mobile node, Alternatively, the present invention can also be applied to a system in which another device different from a mobile node or a fixed node performs mobile node position estimation processing.

  Moreover, although the case where it applied to the frame transmission process in a position estimation system was demonstrated in 1st, 2nd embodiment, it can apply widely also to another radio | wireless communication network system. For example, the IEEE 802.15 series for the PAN (Personal Area Network) area, the IEEE 802.11 series for the LAN (Local Area Network) area, and the IEEE 802.16 series for the MAN (Metropolitan Area Network) The present invention can be applied to a wireless communication network system employing the above.

It is a functional block diagram which shows the internal structure of the fixed node of 1st Embodiment. It is a block diagram which shows the structure of the radio | wireless communication network of 1st Embodiment. It is a functional block diagram which shows the internal structure of the mobile node of 1st Embodiment. It is an operation | movement flowchart of the frame transmission process of 1st Embodiment. It is a functional block diagram which shows the internal structure of the fixed node of 2nd Embodiment. It is a functional block diagram which shows the internal structure of the mobile node of 2nd Embodiment. It is an operation | movement flowchart of the frame transmission process of 2nd Embodiment.

Explanation of symbols

  100, 203 to 208, 500 ... fixed node, 201, 600 ... mobile node, 102, 502 ... received power measuring unit, 103, 302, 503, 602 ... header detecting unit, 104, 606 ... reply signal generating unit, 105, 303, 603: Data reading unit, 106, 304, 506, 604 ... Buffer unit, 107, 507 ... Transmission control unit, 107a ... Counter unit, 107b, 507b ... Timer unit, 504 ... Measurement signal generation unit, 305, 605 ... Position estimation processing unit.

Claims (11)

Receiving means for receiving a radio signal transmitted by a mobile node constituting the radio system and receiving a radio signal transmitted by one or more other nodes toward the mobile node;
Transmitting means for transmitting a transmission signal toward the mobile node;
According to the positional relationship result between the mobile node including each other node obtained based on the reception result of the radio signal from each other node and the reception result of the radio signal from the mobile node, And a communication control unit that controls transmission timing of the transmission signal. The radio signal transmitted by the mobile node is a measurement signal for requesting measurement of received electric field strength,
In response to the measurement request of the mobile node, the wireless signal transmitted by each other node is a return signal including the received electric field strength measured by each other node,
The communication control means is
A reception field strength measurement unit for measuring the reception field strength of the measurement signal from the mobile node;
A reply signal creating unit for creating the reply signal including the received field strength of the measurement signal measured by the received field strength measuring unit;
Based on the reception result of each reply signal from each other node and the received electric field strength of the measurement signal by the received electric field strength measurement unit, the transmission timing of the reply signal created by the reply signal creation unit is autonomous. The communication control apparatus according to claim 1, further comprising: a transmission control unit that controls the communication control unit. The transmission control unit is
An other-node electric field strength extracting unit for extracting the received electric field strength of the measurement signal at each of the other nodes, which is included in each of the return signals from the other nodes;
The received electric field strength at each of the other nodes extracted by the other node electric field strength extracting unit is compared with the received electric field strength by the received electric field strength measuring unit, and the reply signal is determined according to the comparison result. The communication control apparatus according to claim 2, further comprising: a transmission timing adjustment unit that adjusts the transmission timing of the transmission timing.   4. The communication control apparatus according to claim 3, wherein the transmission timing adjustment unit adjusts the transmission timing of the reply signal by setting a holding period of the reply signal according to the comparison result. The received electric field strength measuring unit further measures the received electric field strength of each reply signal received from each other node,
The transmission control unit calculates a value proportional to the reciprocal of the received electric field strength of each return signal of each other node, and adjusts the transmission timing at which the return signal is transmitted at intervals according to each calculation result The communication control apparatus according to claim 2. The receiving means includes a counter unit that counts the number of radio signals from the other nodes,
6. The communication control device according to claim 2, wherein the communication control unit causes the reply signal to be transmitted when a counter value indicated by the counter unit is equal to or less than a predetermined value. . The wireless signal transmitted by each other node is a measurement signal transmitted intermittently,
The wireless signal transmitted by the mobile node is a reply signal that is returned in response to reception of the measurement signal,
The communication control means is
A reception field strength measurement unit for measuring the reception field strength of each measurement signal from each of the other nodes;
A transmission control unit for controlling the transmission timing of the measurement signal based on the reception result of the return signal from the mobile node and the received electric field strength of the measurement signal from each of the other nodes. The communication control device according to claim 1. The received electric field strength measuring unit further measures the received electric field strength of the reply signal received from the mobile node,
The transmission control unit compares the received electric field strength of each measurement signal from each other node with the received electric field strength of the return signal from the mobile node, and according to the comparison result, The communication control apparatus according to claim 7, wherein the transmission timing is adjusted.   The transmission control unit transmits the measurement signal based on the position estimation information of the mobile node and the position information of another node used for the position estimation included in the reply signal from the mobile node. The communication control device according to claim 7, wherein the timing is adjusted.   The node which transmits a radio signal toward the mobile node which comprises a radio | wireless system, The node provided with the communication control apparatus in any one of Claims 1-9.   A radio system comprising a mobile node and a plurality of nodes according to claim 10.

Images