JP2011030035A - Radio communication device, mobile body, radio communication method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication device and method, which suppresses the occurrence of a congestion state in radio communication. <P>SOLUTION: A radio communication device 100 is equipped with: an information management means 120 for holding information on the other radio communication device that exist in a communication area of the radio communication device 100; a radio control means 130 for controlling a radio output outputted to a communication line; and a system control means 110 for making a control in which the number of other communication devices that exist in the communication area is counted by using the information on the other radio communication device and the radio output is reduced when the counted number exceeds a threshold value of the number of devices held in advance. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to wireless communication, and more particularly to a technique for avoiding a congestion state that occurs in wireless communication.

  In wireless communication in a mobile body, a communication method called CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance) is often used as an example. In this method, when the mobile body wishes to transmit a data packet, first, carrier sense (confirmation of the presence or absence of collision) is tried to confirm whether or not the communication line is in use. If any data packet not destined for the node is received, it is determined that the line is in use, and the data packet is retransmitted after waiting for a certain time.

  In such a communication method, if many other mobile units perform communication within the communication area of the mobile unit, it is determined that the line is in use no matter how many times Carrier Sense is repeated, and data packets cannot be transmitted. May occur.

  In addition, in a mobile radio communication system that has been studied by ITS (Intelligent Transport Systems) or the like, there are many mobile communication systems (or fixed base stations) in the communication area for road-to-vehicle communication or inter-vehicle communication. There was a communication partner. As a result, there is a problem that a line capacity such as a radio band and a channel cannot allow all communication in the area, and a congestion (communication is impossible) state occurs.

JP 2008-092435 A

  Therefore, an object of the present invention is to provide a wireless communication apparatus and method for suppressing the occurrence of a congestion state in wireless communication.

  One aspect of the wireless communication device according to the present invention is an information management unit that holds information about another wireless communication device existing in its own communication area, a wireless control unit that controls a wireless output to be output to a communication line, Using information related to other wireless communication devices, the number of other wireless communication devices existing in the communication area is counted, and if the number exceeds a preset number threshold, control to reduce the wireless output is performed. System control means.

  Another aspect of the wireless communication device according to the present invention is an information management means for holding information relating to another wireless communication device existing in its own communication area; and a wireless output to be output to a communication line, wherein the communication line The wireless control means for confirming whether or not is in use, and when the number of times exceeds a pre-use threshold that is stored in advance, control is performed to reduce the wireless output.

  One aspect of the mobile unit according to the present invention includes an information management unit that holds information about other wireless communication devices existing in its own communication area, a wireless control unit that controls wireless output to be output to a communication line, and the other A system that counts the number of other wireless communication devices existing in the communication area using the information related to the wireless communication device, and performs control to reduce the wireless output when the number exceeds a preset number threshold. A wireless communication device including a control means.

  One aspect of the wireless communication method according to the present invention holds information relating to another wireless communication device existing in the own communication area, and exists in the own communication area using the information relating to the other wireless communication device. The number of other wireless communication devices is counted, and when the number exceeds a preset number threshold, control is performed to reduce the wireless output output to the communication line.

  According to one aspect of the program of the present invention, the computer uses the process of holding information related to another wireless communication device existing in the communication area of the computer and the information related to the other wireless communication device, The process of counting the number of other wireless communication devices existing in the network and the process of performing control to reduce the wireless output output to the communication line when the number exceeds the number threshold stored in advance are executed.

  According to the present invention, it is possible to suppress the occurrence of a congestion state in wireless communication.

It is a block diagram which shows the example of 1 structure of the radio | wireless communication apparatus which concerns on this invention. It is a block diagram which shows one structural example of the radio | wireless communication apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the control state of the communication area of Embodiment 1. It is a block diagram which shows one structural example of the radio | wireless communication apparatus which concerns on Embodiment 3 of this invention. It is a figure which shows the control state of the communication area of Embodiment 3. It is a figure which shows another control state of the communication area of Embodiment 3. It is a figure which shows another control state of the communication area of Embodiment 3.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. For clarity of explanation, the following description and drawings are omitted and simplified as appropriate. In the drawings, components having the same configuration or function and corresponding parts are denoted by the same reference numerals and description thereof is omitted.

FIG. 1 is a block diagram showing a configuration example of a wireless communication apparatus according to the present invention. The wireless communication apparatus 100 includes a system control unit 110, an information management unit 120, and a wireless control unit 130. The wireless communication device 100 is a device that performs communication using a wireless communication line (hereinafter referred to as “communication line” as appropriate). For example, communication is performed using a CSMA / CA communication method. Further, the wireless communication device 100 performs wireless output (outputs radio waves) output by itself and communicates with other wireless communication devices. At this time, a range (area) in which the wireless communication apparatus 100 can communicate is determined according to the magnitude of the wireless output. In this specification, this communicable range is called a communication area.
The system control unit 110 controls the overall communication of the wireless communication device 100. Specifically, the information management unit 120 and the radio control unit 130 are controlled to perform communication in conjunction with each other.
The information management unit 120 acquires and holds information necessary for wireless communication. For example, information about other wireless communication devices existing in its own communication area is acquired and held. In addition, the information held periodically is updated. The information management means 20 includes a memory for holding the information.
The radio control unit 130 controls radio output to be output to the communication line. In communication, it is confirmed whether or not the communication line is in use. When the communication line is in use, the communication is performed after the communication line becomes free.

An outline of the operation of the wireless communication method of the present invention will be described.
The information management unit 120 acquires information about other wireless communication devices existing in its own communication area at an arbitrary timing, and stores the information in a memory.
The system control unit 110 holds a unit number threshold value that specifies the number of other wireless communication devices existing in its own communication area. Alternatively, the information management means 120 holds the number threshold, and the system control means 110 refers to this. The system control unit 110 counts the number of other wireless communication devices existing in its own communication area by using information on the other wireless communication device, and if the number exceeds the preset number threshold, the wireless control unit 130 Control to reduce the wireless output.

  In addition, the system control unit 110 controls the magnitude of the wireless output at an arbitrary timing after performing the control for reducing the wireless output. For example, when a predetermined time elapses, when the communication ends, after a predetermined time elapses after the communication ends, or periodically. At this time, the magnitude of the radio output is controlled based on information about other radio communication devices (maintain, decrease, increase the same level, etc.). For example, the system control unit 110 performs control to reduce the wireless output when the number of other wireless communication devices exceeds the number threshold, and the number of other wireless communication devices is equal to or less than the number threshold. In this case, control for increasing the wireless output sequentially may be performed. In addition, the system control unit 110 may control the wireless output based on the state of the collision.

  Hereinafter, an embodiment will be described by taking as an example a case where a wireless communication apparatus uses a CSMA / CA communication method. In the following embodiments, a wireless communication device mounted on a moving body such as a vehicle will be described as an example. However, the present invention is not limited to a wireless communication device used as a vehicle-mounted device, and can be applied to a communication device and method using a communication method for performing wireless communication using a wireless communication line. . Further, the wireless communication apparatus to which the present invention is applied may be one that does not assume movement, for example.

Embodiment 1
FIG. 2 is a block diagram illustrating a configuration example of the wireless communication apparatus according to the first embodiment. Referring to FIG. 2, a wireless communication device 101 mounted on a moving body 200 such as a vehicle includes a system control unit 10, an information management unit 20, a wireless control unit 30, an antenna 40, and a position information acquisition unit 50. It is composed of
The system control unit 10 controls the overall communication of the wireless communication device 100. The information management unit 20, the radio control unit 30, the antenna 40, and the position information acquisition unit 50 are operated in conjunction with each other.

  The information management means (database) 20 includes information on the position, speed, traveling direction, etc. of all or some of the other mobile bodies existing in the communication area of the mobile body 200, received radio wave intensity, etc. It has a function to hold the information. Along with this, the information is updated by beaconing (each mobile unit broadcasts information on its own position, speed, and direction of travel) or location service (a mechanism for inquiring information on the position, speed, and direction of travel of each mobile unit). It has a function to do. The information management unit 20 includes a memory that holds the above-described information.

The wireless control unit 30 has a function of controlling wireless output when the mobile unit transmits and receives data packets, and a function of detecting whether or not a collision on the communication line has occurred during wireless communication.
The antenna 40 has a function of radiating radio waves under the control of the wireless control means 30.
The position information acquisition unit 50 has a function of measuring the current position of the moving body 200. The acquired current position information is notified to the system control means 10 and used when controlling the wireless output.

  Next, the operation of this embodiment will be described with reference to FIG. FIG. 3 is a diagram illustrating a control state of the communication area according to the first embodiment. In FIG. 3, as the mobile body 200 existing in its own communication area 300a, its own mobile body 200-1 (transmission source), the mobile body 200-2 that is the transmission destination of its own mobile body 200-1, and the transmission source The case where the mobile body 200-n other than a transmission destination is included is shown. The mobile body 200-n other than the transmission source and the transmission destination may be one or plural. Further, when the mobile body 200 is simply referred to, the mobile body 200 includes its own mobile body 200-1 and other mobile bodies 200-2 and 200-n. In addition, the own mobile body 200-1 includes its own wireless communication device, and the other mobile bodies 200-2 and 200-n include other wireless communication devices. FIG. 3 shows a change when the wireless output is lowered based on the number of other wireless communication devices (other mobile units). Specifically, an example in which the own communication area 300a (transmission source communication area) is reduced to the communication area 300b (after output control) after wireless output control is shown.

  In FIG. 3, as a representative, mobile bodies other than one transmission source and transmission destination are denoted by reference numerals 200-n, but the same applies to other mobile bodies. Further, the mobile unit 200-1 is distinguished by using the upper right diagonal line and the destination mobile unit 200-2 using the vertical diagonal line. These are the same in the similar drawings used thereafter.

  In radio communication in the mobile unit 200, a communication method called CSMA / CA is often used as an example. In this method, when the mobile unit 200 wants to transmit a data packet, the radio control unit 30 first tries a carrier sense to check whether the communication line is in use. If any data packet not addressed to the node is received, the wireless control unit 30 determines that the line is in use, and waits for a certain time before retransmitting the data packet.

  In addition, each mobile unit 200 periodically broadcasts information on its own location called beaconing, or uses a mechanism that resolves the location of each mobile unit in an inquiry response format called a location service that a fixed station or mobile unit has. can do. By these methods, the position information of other mobile bodies (other wireless communication devices) located in the own communication area, the position information of the mobile body to which the data packet is to be transmitted or the mobile body to be transferred to it, etc. It shall be possible to grasp. This information is updated in a relatively short period of time (eg, once every 100 milliseconds), and the current status of each mobile unit can be grasped almost in real time, while old information is discarded from the information management means 20 And In the configuration of FIG. 2, the information management unit 20 acquires and holds information related to other wireless communication devices.

  In the communication method described above, if many other mobile units 200-2 and 200-n are communicating in the communication area of their own mobile unit 200-1, the line will be connected no matter how many times Carrier Sense is repeated. There is a possibility that the data packet cannot be transmitted because it is determined to be in use.

In the present embodiment, the system control means 10 performs the following control.
(1) Referring to the information management means 20, the number of registered mobile units within the communication area of the mobile unit is counted. Here, it is assumed that the communication area of the mobile body is determined by a prior measurement value, a theoretical calculation value based on electrical characteristics, or the like. At this time, the system control means 10 specifies its own communication area using the current position information acquired by the position information acquisition means 50.
(2) If the number of mobile units in the communication area exceeds the preset maximum value (the number of congestion starts, the unit threshold), wireless output is performed sequentially until the number decreases to a certain value or less. Control to lower. Specifically, the system control unit 10 instructs the radio control unit 30 to gradually decrease the radio output until the other mobile units are reduced below the number threshold. For example, the system control unit 10 may repeatedly instruct the radio control unit 30 to reduce the radio output by an arbitrary numerical value until the other mobile units are reduced to the number threshold or less.

By performing such control to reduce the radio output, the number of other mobile units existing in the own communication area is suppressed, and a potential congestion state is avoided.
It is assumed that the system control unit 10 holds the number threshold in an arbitrary memory in the wireless communication apparatus 101. The number threshold is a value set in advance by the user. The arbitrary memory may be the information management means 20.

  As described above, according to the present embodiment, when there are a number of mobile bodies that can be in a congested state in their own communication area, the number of communicable units can be reduced by reducing the wireless output in advance. be able to. Thereby, it is possible to obtain an effect of avoiding the congestion state in advance. In this way, each mobile unit autonomously determines a congestion state in mobile wireless communication such as ITS and adjusts the wireless output to realize a communication state without congestion.

Embodiment 2
In the first embodiment, control is performed to reduce the wireless output when the number of mobile bodies (wireless communication devices) in the own communication area exceeds the number threshold. However, in this embodiment, the current communication area is further congested. A control method considering the above will be described.
The control method according to the first embodiment does not consider the rate at which wireless communication is actually performed, and thus the communication area may be narrowed despite no congestion. As a result, the destination mobile was originally in its own communication area, so even if direct communication was possible, the destination mobile would be outside the communication area by narrowing the communication area. That happens. Therefore, communication is performed by relaying (multi-hopping) another mobile body to the transmission destination mobile body, which may reduce efficiency.

  Therefore, in the present embodiment, first, when collisions due to Carrier Sense occur continuously, the number n is counted. A case will be described in which, when the counted value reaches a threshold value or more, congestion control according to the above-described method is performed to prevent the wireless output from being unnecessarily lowered and the communication efficiency from being deteriorated.

Since the configuration of the wireless communication apparatus is the same as that of FIG. 2 (or FIG. 1), description thereof is omitted. The wireless control unit 30 confirms whether or not the communication line is in use. At this time, the system control unit 10 controls the radio control unit 30 to reduce the radio output when the number of times that the communication line is confirmed to be in use (the number of times the collision has been detected) exceeds the in-use threshold stored in advance. To do.
The system control unit 10 is premised on holding a busy threshold (collision detection threshold) in an arbitrary memory in the wireless communication apparatus 101. The in-use threshold is a value set in advance by the user. The arbitrary memory may be the information management means 20.

  In the period for counting the number of times, the number of times from when a collision is detected until communication can be started may be counted before one communication is started. Alternatively, the present invention is not limited to before the start of communication, and the wireless control unit 30 may detect a collision by trying Carrier Sense during an arbitrary period, and may count the number of times. Note that the counted number is reset at the timing when the counting period ends or at the timing when counting starts.

The system control unit 10 can control by combining the control based on the number and the control based on the number of times the communication line is being used (the number of collision detections). Specifically, when the number of other moving bodies exceeds the number threshold and the number exceeds the number threshold, control is performed to reduce the wireless output.
Further, the system control means 10 can control the wireless output using only the number of times the communication line is used. In this case, the control based on the number may be invalidated, or the control based on the number may be invalidated by setting an invalid numerical value (such as infinity) for the number threshold.

Embodiment 3
In the third embodiment, the case where the wireless communication apparatus 102 includes an adaptive array antenna instead of the antenna 40 will be described.
In FIG. 4, the antenna 40 in the system configuration of FIG. 2 is replaced with an adaptive array antenna 41, and the adaptive array antenna 41 can control the directivity of radio waves radiated by the wireless control means 30.

  Referring now to FIG. 5, the radio control means 30 of the mobile body 200-1 refers to the position information, speed, traveling direction, and received electric field strength of the mobile body 200-2 that is the transmission destination of the data packet. Then, the directivity and radio wave output of the adaptive array antenna 41 are controlled so as to improve the communication environment with the other party on the basis of the information (that is, information on the destination wireless communication terminal). As a result, the communication area 300a of the mobile unit 200-1 is formed in a form suitable for communication with the mobile unit 200-2 that is the transmission destination of the data packet, and collisions due to data packets from the mobile unit not related to communication are prevented. be able to. FIG. 5 shows an example in which the own communication area 300c is changed to the communication area 300d after radio output and antenna directivity control.

  Next, referring to FIG. 6, when the radio wave transmitted from the mobile body 200-1 is not sufficient as the received electric field strength in the mobile body 200-2 as the transmission destination (eg, there are values of the radio wave intensity and the bit error rate). For example, when the set condition is not satisfied, the mobile body 200-1 receives the received electric field intensity itself of the mobile body 200-2 as a transmission destination or a request message. For example, the mobile unit 200-1 receives a message requesting an increase in output from the mobile unit 200-2 as a transmission destination, or increases the output based on a received RSS (Resource Description Framework). As a result, the radio control means 30 of the moving body 200-1 controls the transmission output and the directivity of the adaptive array antenna 41. Thereby, the communication area 300e of the mobile body 200-1 is formed in a form (communication area 300f) suitable for communication with the mobile body 200-2 that is the transmission destination of the data packet. Alternatively, the adjustment of the reception sensitivity in the wireless control unit 30 may be variable, and the reception sensitivity of the mobile body that is the transmission destination may be increased within a range that is not buried in noise. FIG. 6 shows an example in which the own communication area 300e is changed to the communication area 300f after the radio output and antenna directivity control.

  Further, referring to FIG. 7, when the mobile body 200-1 completes communication with the mobile body 200-2 as the transmission destination, the system control means 10 refers to the information management means 20 and the position distribution of the surrounding mobile bodies Know the speed, direction of travel, etc. Then, the wireless control means 30 is controlled in advance to control the transmission output and the directivity of the adaptive array antenna 41. Thereby, communication with the surrounding mobile body 200-n which can occur next can be started smoothly. FIG. 7 shows an example in which the own communication area 300g is changed to the communication area 300h after wireless output and antenna directivity control.

  As described above, according to the present embodiment, the mobile unit 200-1 controls the directivity of the adaptive array antenna according to the position, speed, and traveling direction of the mobile unit that is the transmission destination of the data packet. Thereby, communication quality can be improved and a congestion state can be avoided. Further, since collisions are avoided for surrounding mobile bodies that are not directly related to the communication of the mobile body 200-1, the mobile bodies 200-n in the surrounding area are also advantageous.

Embodiment 4 FIG.
The control method for avoiding the collision described in each of the above embodiments can be realized using a program. The program is loaded into a memory in the wireless communication device, and causes the computer to execute each process based on control of a CPU (Central Processing Unit). The program executes at least the following processes. (A) Process (information management process) for holding information related to other wireless communication devices existing in its own communication area, (b) Other information existing in its own communication area using information related to other wireless communication devices Processing for counting the number of wireless communication devices (number counting processing), (c) Processing for controlling the wireless control means to reduce the wireless output to be output to the communication line when the counted number exceeds a preset number threshold (wireless) Output control processing).

  When described using the wireless communication apparatus 100 of FIG. 1, the information management unit 120 implements information management processing. Further, the system control unit 110 implements the number counting process and the wireless output control process. The system control unit 110 instructs the wireless control unit 130 to lower the wireless output in the wireless output control process.

As described above, according to one aspect of the wireless communication apparatus of the present invention, the mobile unit detects a collision on the communication line when the mobile unit transmits a data packet, and the position of the mobile unit that is the transmission destination of the data packet , Means for grasping the speed and direction of travel, means for grasping the received radio wave intensity from the mobile object to which the data packet is transmitted, and all or some other mobile objects existing in the communication area of the mobile object And means for grasping the positions, speeds, and traveling directions of all or some of the other moving objects existing in the communication area of the moving object. Then, by controlling the wireless output, the number of mobile bodies existing in the own communication area is controlled.
Further, it has means for grasping the received radio wave intensity from all or some other mobile objects existing in the communication area of the mobile object, and controls the radio output based on the received intensity. Furthermore, it has means for controlling the radio wave transmission output and antenna directivity of the mobile body based on various conditions, and controls the radio output and the directivity of the adaptive array antenna.

In addition, one of the embodiments of the present invention has a function of performing the following control.
(1) A function of performing wireless output control for avoiding congestion based on the information on the number of other mobile units in the communication area of the mobile unit.
(2) A function of performing wireless output control for avoiding congestion based on the number of times of detection of the line usage state by Carrier Sense in addition to the information on the number of other mobile units in the communication area of the mobile unit.
(3) In order to improve the current communication environment with the mobile unit that is the transmission destination of the data packet transmitted by the mobile unit, information on the position, speed, traveling direction, and received electric field strength of the mobile unit that is the transmission destination A function that originally controls the appropriate radio output and the directivity of the adaptive array antenna.
(4) Based on the information on the position, speed, traveling direction, and received electric field strength of other mobile units within the communication area of the mobile unit, appropriate radio output for the next communication and the orientation of the adaptive array antenna The ability to control gender.

  In addition, this invention is not limited to embodiment shown above. Within the scope of the present invention, it is possible to change, add, or convert each element of the above-described embodiment to a content that can be easily considered by those skilled in the art.

100, 101, 102 Radio communication apparatus 10, 110 System control means 20, 120 Information management means 30, 130 Radio control means 40, 41 Antenna 200, 200-1, 200-2, 200-n Mobile unit 300, 300a to 300h Communication area

Claims (14)

Information management means for holding information related to other wireless communication devices existing in its own communication area;
Wireless control means for controlling the wireless output to be output to the communication line;
Using the information related to the other wireless communication device, count the number of other wireless communication devices existing in the communication area of the self, and if the number exceeds the number threshold stored in advance, control to reduce the wireless output And a system control unit for performing wireless communication. The wireless control means confirms whether the communication line is in use,
2. The wireless communication according to claim 1, wherein the system control unit performs control to reduce the wireless output when the number of times when it is confirmed that the communication line is in use exceeds a busy threshold that is held in advance. apparatus.   3. The wireless communication according to claim 2, wherein the system control unit performs control to reduce the wireless output when the number exceeds the number threshold and the number exceeds the number in use. apparatus. 4. The system control unit according to claim 1, wherein the system control unit performs control to sequentially reduce the wireless output until the number of other wireless communication devices existing in the communication area of the system becomes equal to or less than the number. 5. The wireless communication device according to any one of the above. Information management means for holding information related to other wireless communication devices existing in its own communication area;
Wireless control means for controlling the wireless output to be output to the communication line and confirming whether the communication line is in use;
A wireless communication apparatus that performs control to reduce the wireless output when the number of times exceeds a pre-use threshold that is held in advance.   The said system control means performs control which raises a radio | wireless output based on the information of the other radio | wireless communication apparatus which the said information management means hold | maintains, The Claim 1 thru | or 5 characterized by the above-mentioned. Wireless communication device. Further comprising an adaptive array antenna having directivity,
The system control means controls the magnitude of wireless output based on information of other wireless communication devices held by the information management means,
The wireless control unit according to any one of claims 1 to 6, wherein the wireless control unit controls the adaptive array antenna based on information of another wireless communication device held by the information management unit. Communication device.   8. The wireless communication apparatus according to claim 7, wherein the wireless control unit controls the adaptive array antenna based on information of a wireless communication apparatus that is a transmission destination.   The wireless communication device according to claim 7 or 8, wherein the wireless control unit controls the adaptive array antenna based on information of a wireless communication device other than a transmission destination.   10. The wireless control unit according to claim 1, wherein the wireless control unit checks whether or not the communication line is in use by using a CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance) procedure. The wireless communication device according to one item.   The wireless communication device according to claim 1, wherein the wireless communication device is an in-vehicle device. Information management means for holding information related to other wireless communication devices existing in its own communication area;
Wireless control means for controlling the wireless output to be output to the communication line;
Using the information related to the other wireless communication device, count the number of other wireless communication devices existing in the communication area of the self, and if the number exceeds the number threshold stored in advance, control to reduce the wireless output A mobile unit equipped with a wireless communication device. Holds information about other wireless communication devices that exist in your communication area,
Using information about the other wireless communication device, count the number of other wireless communication devices present in the communication area of the self,
A wireless communication method for performing control to reduce a wireless output to be output to a communication line when the number exceeds a number threshold stored in advance. On the computer,
A process of holding information about other wireless communication devices existing in its own communication area;
Using the information about the other wireless communication device, a process of counting the number of other wireless communication devices existing in the own communication area;
A program for executing a control for reducing a wireless output to be output to a communication line when the number exceeds a number threshold stored in advance.

Images