WO2013061589A1 - Wireless tag device, wireless communication system, and resend control method - Google Patents

Wireless tag device, wireless communication system, and resend control method Download PDF

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WO2013061589A1
WO2013061589A1 PCT/JP2012/006831 JP2012006831W WO2013061589A1 WO 2013061589 A1 WO2013061589 A1 WO 2013061589A1 JP 2012006831 W JP2012006831 W JP 2012006831W WO 2013061589 A1 WO2013061589 A1 WO 2013061589A1
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priority
area
distance
determination
reception strength
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PCT/JP2012/006831
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French (fr)
Japanese (ja)
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剛史 瀧口
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パナソニック株式会社
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Priority to CN201280053019.1A priority Critical patent/CN104025123A/en
Publication of WO2013061589A1 publication Critical patent/WO2013061589A1/en
Priority to IN3954CHN2014 priority patent/IN2014CN03954A/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0015—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the adaptation strategy
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S1/00—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith
    • G01S1/02—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith using radio waves
    • G01S1/68—Marker, boundary, call-sign, or like beacons transmitting signals not carrying directional information
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
    • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
    • G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
    • G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
    • G06K19/0723—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
    • G06K7/10009—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
    • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
    • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
    • H04L1/1867—Arrangements specially adapted for the transmitter end
    • H04L1/1887—Scheduling and prioritising arrangements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/30—Services specially adapted for particular environments, situations or purposes
    • H04W4/40—Services specially adapted for particular environments, situations or purposes for vehicles, e.g. vehicle-to-pedestrians [V2P]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/80—Services using short range communication, e.g. near-field communication [NFC], radio-frequency identification [RFID] or low energy communication
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/02—Services making use of location information
    • H04W4/023—Services making use of location information using mutual or relative location information between multiple location based services [LBS] targets or of distance thresholds
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W64/00—Locating users or terminals or network equipment for network management purposes, e.g. mobility management
    • H04W64/006—Locating users or terminals or network equipment for network management purposes, e.g. mobility management with additional information processing, e.g. for direction or speed determination
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/50—Allocation or scheduling criteria for wireless resources
    • H04W72/56—Allocation or scheduling criteria for wireless resources based on priority criteria
    • H04W72/566—Allocation or scheduling criteria for wireless resources based on priority criteria of the information or information source or recipient
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access
    • H04W74/08—Non-scheduled access, e.g. ALOHA
    • H04W74/0833—Random access procedures, e.g. with 4-step access
    • H04W74/0841—Random access procedures, e.g. with 4-step access with collision treatment
    • H04W74/085—Random access procedures, e.g. with 4-step access with collision treatment collision avoidance

Definitions

  • a large number of sensors are installed along the expressway.
  • response signals are transmitted from a plurality of wireless tag devices in response to response request signals (beacon signals) from the wireless reader device, and they collide ( Collision).
  • response request signals beacon signals
  • collide Collision
  • one wireless tag device succeeds in communication with the wireless reader device, while another wireless tag device fails in communication with the wireless reader device.
  • the wireless reader device and the wireless tag device are close to each other and are close to each other in the short-distance approaching area, it is considered that there are more opportunities for retransmission than the short-distance leaving area.
  • Set to priority third priority.
  • the lowest priority fourth priority is set.
  • an appropriate priority can be set on the wireless tag device side according to the number of future retransmission opportunities, and the retransmission timing is appropriately controlled based on the priority. be able to.
  • the retransmission control method of the present invention is a retransmission control method used in a wireless tag device, which receives a response request signal transmitted from a wireless reader device, measures the reception strength of the response request signal, and responds to the response request signal.
  • the response signal transmitted as is received by the wireless reader device to determine whether the communication with the wireless reader device is successful, based on the reception strength of the previous response request signal and the reception strength of the current response request signal, When the reception strength is increasing, it is determined as approaching, and when the reception strength is decreasing, it is determined as moving, and the reception strength is determined based on the reception strength of the current response request signal. If the received intensity is less than the threshold value, the distance is determined to be a long distance.
  • the priority of the short distance departure area is the second priority lower than the first priority
  • the priority of the short distance approach area is the third priority lower than the second priority.
  • the priority of the long-distance approaching area is the fourth priority that is lower than the third priority.
  • the RSSI of the beacon signal received this time is compared with the threshold, and when the RSSI is equal to or greater than the threshold, it is determined as “near distance (near)”, and when the RSSI is less than the threshold, “ It is determined as “far (far)”.
  • the wireless tag device 2 includes a transmission timing control unit 13.
  • the transmission timing control unit 13 has a function of determining a timing (in which time slot to transmit) an ACK signal for a beacon signal.
  • the wireless tag device 2 includes a random number generator 14.
  • the random number generator 14 generates a random number for performing random control.
  • the transmission timing control is a random control in which a time slot for transmitting an ACK signal is randomly assigned based on the random number generated by the random number generation unit 14.
  • FIG. 4 shows an example of a radio frame configuration.
  • one frame is composed of two units (first unit and second unit), and one unit is composed of 45 subframes (first subframe to 45th subframe). It is assumed that n time slots are included in one frame.
  • control of retransmission timing of response signals is performed so that the higher the priority, the greater the number of retransmissions per predetermined period (for example, one frame).
  • one frame is composed of two units (first unit and second unit), and one unit has 45 subframes (first subframe to 45th subframe).
  • the response signal is retransmitted in all 45 subframes (first subframe to 45th subframe) of the second unit, and if it is a short distance departure area, the second unit The response signal is retransmitted in 30 subframes (for example, the 16th subframe to the 45th subframe). If it is a short-distance approach area, the response signal is retransmitted in 20 subframes (for example, the 26th to 45th subframes) of the second unit. If it is a long-distance approach area, the second unit The response signal is retransmitted in 10 subframes (for example, the 36th to 45th subframes).

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Toxicology (AREA)
  • Theoretical Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Electromagnetism (AREA)
  • General Health & Medical Sciences (AREA)
  • Artificial Intelligence (AREA)
  • Remote Sensing (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Quality & Reliability (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Near-Field Transmission Systems (AREA)

Abstract

A wireless tag device (2) receives a response request signal from a wireless reader device (3) and measures the receiving strength thereof. In response to the response request signal, the wireless tag device (2) determines whether a communication with the wireless reader device (3) was successful. The wireless tag device (2) carries out a movement determination on the basis of the increase or decrease of the receiving strength, compares the receiving strength with a threshold and carries out a distance determination, and carries out an area determination on the basis of the results of the movement determination and the distance determination. When the communication with the wireless reader device (3) fails, the wireless tag device (2) controls, on the basis of the result of the area determination, resend timing according to priorities which are determined for each area (long-distance separation: maximum; near-distance separation: high; near-distance approach: medium; long-distance approach: low). It is thus possible, when communication with the wireless reader device has failed, to set appropriate priorities according to the number of future resend opportunities, and to appropriately control resending on the basis of the priorities.

Description

無線タグ装置、無線通信システムおよび再送制御方法Wireless tag device, wireless communication system, and retransmission control method
　本発明は、無線リーダ装置との通信が失敗したときに再送制御を行う機能を備えた無線タグ装置に関するものである。 The present invention relates to a wireless tag device having a function of performing retransmission control when communication with a wireless reader device fails.
　従来、高速道路の道路脇などにセンサを設置しておき、そのセンサで測定したセンサ情報（計測データ）をセンサの近傍に設置した路側ユニットで記録し、車両に搭載された車載ユニットで近傍を通過する際に、車両を走行させながら、その路側ユニットからセンサ情報を無線通信で収集するシステムが提案されている（例えば、特許文献１参照）。この場合、車載ユニットが無線リーダ装置に相当し、路側ユニットが無線タグ装置に相当する。 Conventionally, a sensor is installed on the side of an expressway, and sensor information (measurement data) measured by the sensor is recorded by a roadside unit installed in the vicinity of the sensor, and the vicinity is detected by an in-vehicle unit mounted on the vehicle. There has been proposed a system that collects sensor information from a roadside unit by wireless communication while traveling a vehicle while passing (see, for example, Patent Document 1). In this case, the in-vehicle unit corresponds to a wireless reader device, and the roadside unit corresponds to a wireless tag device.
　このようなシステムでは、高速道路に沿って多数のセンサが設置される。無線リーダ装置の通信可能エリアの圏内に多数の無線タグ装置が存在すると、無線リーダ装置からの応答要求信号（ビーコン信号）に対して複数の無線タグ装置から応答信号が送信され、それらが衝突（コリジョン）することもあり得る。無線タグ装置からの応答で衝突（コリジョン）が発生すると、ある無線タグ装置は、無線リーダ装置との通信に成功するが、他の無線タグ装置は、無線リーダ装置との通信に失敗する結果となる。 In such a system, a large number of sensors are installed along the expressway. When a large number of wireless tag devices exist within the communicable area of the wireless reader device, response signals are transmitted from a plurality of wireless tag devices in response to response request signals (beacon signals) from the wireless reader device, and they collide ( Collision). When a collision occurs due to a response from the wireless tag device, one wireless tag device succeeds in communication with the wireless reader device, while another wireless tag device fails in communication with the wireless reader device. Become.
　無線リーダ装置との通信に失敗した場合、一般に、応答信号を再送する再送制御が行われる（例えば、特許文献２参照）。例えば、従来の再送制御方法では、無線通信装置（無線リーダ装置）で、無線端末装置（無線タグ装置）の送信失敗回数に応じたタイムスロットをランダムに割り当てて、無線タグ装置に通知する。無線タグ装置では、無線リーダ装置により割り当てられたタイムスロットで再送が行われる。 When communication with the wireless reader device fails, generally, retransmission control is performed to retransmit the response signal (see, for example, Patent Document 2). For example, in a conventional retransmission control method, a wireless communication device (wireless reader device) randomly assigns a time slot corresponding to the number of transmission failures of a wireless terminal device (wireless tag device) and notifies the wireless tag device. In the wireless tag device, retransmission is performed in the time slot assigned by the wireless reader device.
　しかしながら、従来の方法では、再送制御の主たる制御が無線リーダ装置側で行われており、無線タグ装置の台数が多くなると、無線リーダ装置側の処理が重くなる。 However, in the conventional method, the main control of the retransmission control is performed on the wireless reader device side, and as the number of wireless tag devices increases, the processing on the wireless reader device side becomes heavy.
　また、高速道路を走行する車両の速度は、高速（例えば時速８０ｋｍ）である。無線リーダ装置が高速で移動する場合、無線タグ装置がすぐに通信可能エリアの圏外に出てしまうため、再送可能な期間が短い。ところが、再送可能な期間が短い場合には、再送タイミング（タイムスロット）をランダムに割り当てると、再コリジョンが発生する可能性が高くなる。 Also, the speed of the vehicle traveling on the highway is high speed (for example, 80 km / h). When the wireless reader device moves at a high speed, the wireless tag device immediately goes out of the communicable area, so that the retransmittable period is short. However, when the retransmittable period is short, the possibility of re-collision increases if the retransmission timing (time slot) is randomly assigned.
　無線リーダ装置が高速で移動する（無線タグ装置がすぐに通信可能エリアの圏外に出てしまう）ということは、今後、その無線タグ装置から再送できる機会が少ないともいえる。それにも関わらず、再コリジョンが発生してしまうと、少ない機会を逃してしまう結果となる。 The fact that the wireless reader device moves at high speed (the wireless tag device immediately goes out of the communication area) can be said to have few opportunities for retransmission from the wireless tag device in the future. Nevertheless, if a re-collision occurs, it will result in missed opportunities.
特開２０１０－１１７８３７号公報JP 2010-117837 A 特開２００９－２１８６７２号公報JP 2009-218672 A
　本発明は、上記背景の下でなされたものである。本発明の目的は、無線リーダ装置との通信が失敗したときに、今後の再送の機会の多寡に応じて適切な優先度を設定し、その優先度に基づいて適切な再送制御をすることのできる無線タグ装置を提供することにある。 The present invention has been made under the above background. An object of the present invention is to set an appropriate priority according to the number of future retransmission opportunities when communication with the wireless reader device fails, and to perform appropriate retransmission control based on the priority. An object of the present invention is to provide a wireless tag device that can be used.
　本発明の一の態様は、無線タグ装置であり、この無線タグ装置は、無線リーダ装置から送信される応答要求信号を受信する受信部と、応答要求信号の受信強度を測定する受信強度測定部と、応答要求信号に対する応答として送信した応答信号が無線リーダ装置で受け付けられて無線リーダ装置との通信が成功したか否か判定する通信成否判定部と、以前の応答要求信号の受信強度と今回の応答要求信号の受信強度とに基づいて、受信強度が増加している場合には接近と判定し、受信強度が減少している場合には離脱と判定する移動判定を行う移動判定部と、今回の応答要求信号の受信強度に基づいて、受信強度が所定の閾値以上である場合には近距離と判定し、受信強度が閾値未満である場合には遠距離と判定する遠近判定を行う遠近判定部と、移動判定と遠近判定の判定結果に基づいて、遠距離離脱エリア、近距離離脱エリア、近距離接近エリア、遠距離接近エリアのいずれのエリアに属するかを判定するエリア判定を行うエリア判定部と、無線リーダ装置との通信が失敗したと判定された場合に、エリア判定の判定結果に基づいて、エリアごとに定められた優先度に応じて、応答信号を再送する再送タイミングを制御する再送タイミング制御部と、を備え、遠距離離脱エリアの優先度は最も高い第１優先度であり、近距離離脱エリアの優先度は第１優先度より低い第２優先度であり、近距離接近エリアの優先度は第２優先度より低い第３優先度であり、遠距離接近エリアの優先度は第３優先度より低い第４優先度である。 One aspect of the present invention is a wireless tag device, which includes a reception unit that receives a response request signal transmitted from a wireless reader device, and a reception strength measurement unit that measures the reception strength of the response request signal. A response signal transmitted as a response to the response request signal is received by the wireless reader device, and a communication success / failure determination unit that determines whether or not the communication with the wireless reader device is successful, the reception strength of the previous response request signal and the current time Based on the reception strength of the response request signal, a movement determination unit that performs a movement determination that determines that it is approaching when the reception strength is increased, and that is determined to be detached when the reception strength is decreased; Based on the reception strength of the response request signal this time, when the reception strength is greater than or equal to a predetermined threshold, it is determined as a near distance, and when the reception strength is less than the threshold, a perspective determination is performed that determines a long distance. Judgment And an area determination unit that performs area determination to determine which of the long-distance departure area, the short-distance departure area, the short-distance approach area, and the long-distance approach area based on the determination result of the movement determination and the perspective determination If the communication with the wireless reader device is determined to have failed, the retransmission for controlling the retransmission timing for retransmitting the response signal according to the priority determined for each area based on the determination result of the area determination A long-distance departure area with the highest priority, the short-distance departure area with a second priority lower than the first priority, and a short-distance approach area. Is a third priority lower than the second priority, and the priority of the long-distance approaching area is the fourth priority lower than the third priority.
　以下に説明するように、本発明には他の態様が存在する。したがって、この発明の開示は、本発明の一部の態様の提供を意図しており、ここで記述され請求される発明の範囲を制限することは意図していない。 As described below, there are other aspects of the present invention. Accordingly, this disclosure is intended to provide some aspects of the invention and is not intended to limit the scope of the invention described and claimed herein.
図１は、本発明の第１の実施の形態における無線通信システムのブロック図FIG. 1 is a block diagram of a radio communication system according to a first embodiment of the present invention. 図２は、本発明の第１の実施の形態における無線通信システムの説明図FIG. 2 is an explanatory diagram of the radio communication system according to the first embodiment of this invention. 図３は、本発明の第１の実施の形態における４つのエリア（遠距離接近エリア、近距離接近エリア、近距離離脱エリア、遠距離離脱エリア）およびそれらの優先度の説明図FIG. 3 is an explanatory diagram of four areas (long-distance approaching area, short-distance approaching area, short-distance leaving area, long-distance leaving area) and their priorities in the first embodiment of the present invention. 図４は、本発明の第１の実施の形態における無線フレーム構成の説明図FIG. 4 is an explanatory diagram of a radio frame configuration according to the first embodiment of this invention. 図５は、本発明の第１の実施の形態における再送制御を説明するためのシーケンス図FIG. 5 is a sequence diagram for explaining retransmission control according to the first embodiment of the present invention. 図６は、本発明の第２の実施の形態における無線通信システムのブロック図FIG. 6 is a block diagram of a radio communication system according to the second embodiment of the present invention. 図７は、本発明の第２の実施の形態におけるフリンジ通過の説明図FIG. 7 is an explanatory view of fringe passage in the second embodiment of the present invention. 図８は、本発明の第２の実施の形態における無線フレーム構成の説明図FIG. 8 is an explanatory diagram of a radio frame configuration according to the second embodiment of the present invention. 図９は、本発明の第２の実施の形態における事前送信制御を説明するためのシーケンス図FIG. 9 is a sequence diagram for explaining pre-transmission control in the second embodiment of the present invention.
　以下に本発明の詳細な説明を述べる。ただし、以下の詳細な説明と添付の図面は発明を限定するものではない。 The detailed description of the present invention will be described below. However, the following detailed description and the accompanying drawings do not limit the invention.
　本発明の無線タグ装置は、無線リーダ装置から送信される応答要求信号を受信する受信部と、応答要求信号の受信強度を測定する受信強度測定部と、応答要求信号に対する応答として送信した応答信号が無線リーダ装置で受け付けられて無線リーダ装置との通信が成功したか否か判定する通信成否判定部と、以前の応答要求信号の受信強度と今回の応答要求信号の受信強度とに基づいて、受信強度が増加している場合には接近と判定し、受信強度が減少している場合には離脱と判定する移動判定を行う移動判定部と、今回の応答要求信号の受信強度に基づいて、受信強度が所定の閾値以上である場合には近距離と判定し、受信強度が閾値未満である場合には遠距離と判定する遠近判定を行う遠近判定部と、移動判定と遠近判定の判定結果に基づいて、遠距離離脱エリア、近距離離脱エリア、近距離接近エリア、遠距離接近エリアのいずれのエリアに属するかを判定するエリア判定を行うエリア判定部と、無線リーダ装置との通信が失敗したと判定された場合に、エリア判定の判定結果に基づいて、エリアごとに定められた優先度に応じて、応答信号を再送する再送タイミングを制御する再送タイミング制御部と、を備え、遠距離離脱エリアの優先度は最も高い第１優先度であり、近距離離脱エリアの優先度は第１優先度より低い第２優先度であり、近距離接近エリアの優先度は第２優先度より低い第３優先度であり、遠距離接近エリアの優先度は第３優先度より低い第４優先度である構成を有している。 The wireless tag device of the present invention includes a reception unit that receives a response request signal transmitted from a wireless reader device, a reception intensity measurement unit that measures the reception intensity of the response request signal, and a response signal transmitted as a response to the response request signal Is received by the wireless reader device and based on the communication success / failure determination unit that determines whether or not the communication with the wireless reader device is successful, and the reception strength of the previous response request signal and the reception strength of the current response request signal, When the reception strength is increasing, it is determined as approaching, and when the reception strength is decreasing, based on the reception strength of the response request signal this time, and a movement determination unit that performs a movement determination that determines separation. When the reception intensity is equal to or greater than a predetermined threshold, the distance is determined to be a short distance, and when the reception intensity is less than the threshold, the distance determination unit that performs the distance determination to determine the distance, and the determination result of the movement determination and the distance determination In Therefore, communication between the wireless reader device and the area determination unit that performs area determination to determine whether it belongs to the long-distance departure area, the short-distance departure area, the short-distance approach area, or the long-distance approach area has failed. A retransmission timing control unit that controls retransmission timing for retransmitting the response signal according to the priority determined for each area based on the determination result of the area determination. The priority of the area is the highest first priority, the priority of the short distance departure area is the second priority lower than the first priority, and the priority of the short distance approach area is lower than the second priority. The priority of the long-distance approaching area is the fourth priority that is lower than the third priority.
　この構成により、無線リーダ装置からの応答要求信号の受信強度（例えば、ＲＳＳＩ）に基づいて移動判定と遠近判定が行われ、無線タグ装置の属するエリアが「遠距離離脱エリア」「近距離離脱エリア」「近距離接近エリア」「遠距離接近エリア」のいずれであるかが判定される。無線リーダ装置との通信が失敗したと判定されると、各エリアごとに定められた優先度に応じて、応答信号を再送する再送タイミングが制御される。例えば、遠距離離脱エリアは、無線リーダ装置と無線タグ装置が遠距離にあり互いに離脱している（遠ざかっている）ため、今後の再送の機会が最も少ない（間もなく通信可能エリアの圏外に出てしまう）と考えられるので、最も高い優先度（第１優先度）に設定され、最優先で応答信号が再送される。また、近距離離脱エリアは、無線リーダ装置と無線タグ装置が近距離にあるものの互いに離脱している（遠ざかっている）ため、今後の再送の機会が遠距離離脱エリアの次に少ないと考えられるので、その次に高い優先度（第２優先度）に設定される。さらに、近距離接近エリアは、無線リーダ装置と無線タグ装置が近距離にあり互いに接近している（近づいている）ため、近距離離脱エリアより再送の機会が多いと考えられるので、その次の優先度（第３優先度）に設定される。そして、遠距離接近エリアは、無線リーダ装置と無線タグ装置が遠距離にあり互いに接近している（近づいている）ため、今後の再送の機会が最も多い（しばらく通信可能エリアの圏内に滞在する）と考えられるため、最も低い優先度（第４優先度）に設定される。このように、本発明によれば、無線タグ装置側で、今後の再送の機会の多寡に応じて適切な優先度を設定することができ、その優先度に基づいて再送タイミングを適切に制御することができる。 With this configuration, the movement determination and the perspective determination are performed based on the reception strength (for example, RSSI) of the response request signal from the wireless reader device, and the area to which the wireless tag device belongs is “long distance departure area”, “short distance departure area” It is determined whether it is “a short-distance approaching area” or “a long-distance approaching area”. If it is determined that communication with the wireless reader device has failed, the retransmission timing for retransmitting the response signal is controlled according to the priority determined for each area. For example, in the long-distance leaving area, the wireless reader device and the RFID tag device are at a long distance and are separated (distant) from each other, so there are few opportunities for future retransmission (coming soon out of the communicable area) Therefore, the highest priority (first priority) is set, and the response signal is retransmitted with the highest priority. In addition, the short-distance leaving area is considered to have the next few chances of retransmission next to the long-distance leaving area because the wireless reader device and the RFID tag device are located at a short distance but are separated from each other. Therefore, the second highest priority (second priority) is set. Furthermore, since the wireless reader device and the wireless tag device are close to each other and are close to each other in the short-distance approaching area, it is considered that there are more opportunities for retransmission than the short-distance leaving area. Set to priority (third priority). In the long-distance approach area, since the wireless reader device and the wireless tag device are at a long distance and are close to each other (approaching), there are most opportunities for future retransmissions (staying within the communicable area for a while) ), The lowest priority (fourth priority) is set. As described above, according to the present invention, an appropriate priority can be set on the wireless tag device side according to the number of future retransmission opportunities, and the retransmission timing is appropriately controlled based on the priority. be able to.
　また、本発明の無線タグ装置では、再送タイミング制御部は、優先度が高いほど所定期間あたりの再送回数が多くなるように、応答信号の再送タイミングを制御する構成を有してよい。 Further, in the wireless tag device of the present invention, the retransmission timing control unit may have a configuration for controlling the retransmission timing of the response signal so that the higher the priority, the greater the number of retransmissions per predetermined period.
　この構成により、優先度が高いほど所定期間（例えば１フレーム）あたりの再送回数が多くなるように、応答信号の再送タイミングの制御（再送制御）が行われる。例えば、１つのフレームが、２つのユニット（第１ユニットおよび第２ユニット）で構成され、１つのユニットが４５個のサブフレーム（第１サブフレーム～第４５サブフレーム）で構成されている場合に、第１ユニットで無線リーダ装置との通信が失敗したとする。その場合、遠距離離脱エリアであれば、第２ユニットの４５個のサブフレームすべて（第１サブフレーム～第４５サブフレーム）で応答信号を再送し、近距離離脱エリアであれば、第２ユニットの３０個のサブフレーム（例えば、第１６サブフレーム～第４５サブフレーム）で応答信号を再送する。また、近距離接近エリアであれば、第２ユニットの２０個のサブフレーム（例えば、第２６サブフレーム～第４５サブフレーム）で応答信号を再送し、遠距離接近エリアであれば、第２ユニットの１０個のサブフレーム（例えば、第３６サブフレーム～第４５サブフレーム）で応答信号を再送する。このように、本発明によれば、今後の再送の機会の多寡に応じた再送回数となるように、再送タイミングを適切に制御することができる。 With this configuration, the retransmission timing of the response signal (retransmission control) is performed so that the higher the priority, the greater the number of retransmissions per predetermined period (for example, one frame). For example, when one frame is composed of two units (first unit and second unit), and one unit is composed of 45 subframes (first subframe to 45th subframe). Assume that communication with the wireless reader device has failed in the first unit. In that case, if it is a long distance departure area, the response signal is retransmitted in all 45 subframes (first subframe to 45th subframe) of the second unit, and if it is a short distance departure area, the second unit The response signal is retransmitted in 30 subframes (for example, the 16th subframe to the 45th subframe). If it is a short-distance approach area, the response signal is retransmitted in 20 subframes (for example, the 26th to 45th subframes) of the second unit. If it is a long-distance approach area, the second unit The response signal is retransmitted in 10 subframes (for example, the 36th to 45th subframes). As described above, according to the present invention, it is possible to appropriately control the retransmission timing so that the number of retransmissions according to the number of retransmission opportunities in the future.
　また、本発明の無線タグ装置は、遠近判定で遠距離と判定された場合には、再送タイミング制御部で決定される再送タイミングより前のタイミングで、応答信号を事前に送信する事前送信制御部を備えた構成を有してよい。 In addition, the wireless tag device of the present invention has a pre-transmission control unit that transmits a response signal in advance at a timing before the retransmission timing determined by the retransmission timing control unit when it is determined as a long distance in the perspective determination You may have the structure provided with.
　この構成により、無線リーダ装置との通信が失敗したと判定された場合に、遠近判定で遠距離と判定されると、上記の再送タイミング制御部で決定される再送タイミングより前のタイミングで、応答信号が事前に送信される。例えば、無線リーダ装置の通信可能エリアの縁（フリンジ）の部分をかするように無線タグ装置が通過する場合、今後の再送の機会が最も少ない（間もなく通信可能エリアの圏外に出てしまう）と考えられる。本発明によれば、そのような場合に、再送タイミングより前のタイミングで応答信号が事前に再送されるので、無線リーダ装置との通信の成功率を更に高めることができる。 With this configuration, when it is determined that communication with the wireless reader device has failed, if it is determined that the distance is determined to be a long distance in the perspective determination, a response is received at a timing before the retransmission timing determined by the retransmission timing control unit. A signal is transmitted in advance. For example, when the wireless tag device passes so as to cover the edge (fringe) of the communicable area of the wireless reader device, there is the least chance of future retransmission (coming soon out of the communicable area). Conceivable. According to the present invention, in such a case, since the response signal is retransmitted in advance at a timing before the retransmission timing, the success rate of communication with the wireless reader device can be further increased.
　本発明の再送制御方法は、無線タグ装置で用いられる再送制御方法であって、無線リーダ装置から送信される応答要求信号を受信し、応答要求信号の受信強度を測定し、応答要求信号に対する応答として送信した応答信号が無線リーダ装置で受け付けられて無線リーダ装置との通信が成功したか否か判定し、以前の応答要求信号の受信強度と今回の応答要求信号の受信強度とに基づいて、受信強度が増加している場合には接近と判定し、受信強度が減少している場合には離脱と判定する移動判定を行い、今回の応答要求信号の受信強度に基づいて、受信強度が所定の閾値以上である場合には近距離と判定し、受信強度が閾値未満である場合には遠距離と判定する遠近判定を行い、移動判定と遠近判定の判定結果に基づいて、遠距離離脱エリア、近距離離脱エリア、近距離接近エリア、遠距離接近エリアのいずれのエリアに属するかを判定するエリア判定を行い、無線リーダ装置との通信が失敗したと判定された場合に、エリア判定の判定結果に基づいて、エリアごとに定められた優先度に応じて、応答信号を再送する再送タイミングを制御するものであり、遠距離離脱エリアの優先度は最も高い第１優先度であり、近距離離脱エリアの優先度は第１優先度より低い第２優先度であり、近距離接近エリアの優先度は第２優先度より低い第３優先度であり、遠距離接近エリアの優先度は第３優先度より低い第４優先度である。 The retransmission control method of the present invention is a retransmission control method used in a wireless tag device, which receives a response request signal transmitted from a wireless reader device, measures the reception strength of the response request signal, and responds to the response request signal. The response signal transmitted as is received by the wireless reader device to determine whether the communication with the wireless reader device is successful, based on the reception strength of the previous response request signal and the reception strength of the current response request signal, When the reception strength is increasing, it is determined as approaching, and when the reception strength is decreasing, it is determined as moving, and the reception strength is determined based on the reception strength of the current response request signal. If the received intensity is less than the threshold value, the distance is determined to be a long distance. Based on the determination result of the movement determination and the distance determination, a long distance departure area is determined. Area determination is performed to determine whether the area belongs to a short distance departure area, a short distance approach area, or a long distance approach area, and if it is determined that communication with the wireless reader device has failed, determination of area determination Based on the result, the retransmission timing for retransmitting the response signal is controlled according to the priority determined for each area, and the priority of the long-distance departure area is the highest first priority, and the short distance The priority of the leaving area is a second priority lower than the first priority, the priority of the short-distance approaching area is a third priority lower than the second priority, and the priority of the long-distance approaching area is third. The fourth priority is lower than the priority.
　この方法によっても、上記と同様に、無線タグ装置側で、今後の再送の機会の多寡に応じて適切な優先度を設定することができ、その優先度に基づいて再送タイミングを適切に制御することができる。 Also in this method, as described above, an appropriate priority can be set on the wireless tag device side in accordance with the number of future retransmission opportunities, and the retransmission timing is appropriately controlled based on the priority. be able to.
　本発明の無線通信システムは、無線タグ装置と無線リーダ装置とを備えた無線通信システムであって、無線タグ装置は、無線リーダ装置から送信される応答要求信号を受信する受信部と、応答要求信号の受信強度を測定する受信強度測定部と、応答要求信号に対する応答として送信した応答信号が無線リーダ装置で受け付けられて無線リーダ装置との通信が成功したか否か判定する通信成否判定部と、以前の応答要求信号の受信強度と今回の応答要求信号の受信強度とに基づいて、受信強度が増加している場合には接近と判定し、受信強度が減少している場合には離脱と判定する移動判定を行う移動判定部と、今回の応答要求信号の受信強度に基づいて、受信強度が所定の閾値以上である場合には近距離と判定し、受信強度が閾値未満である場合には遠距離と判定する遠近判定を行う遠近判定部と、移動判定と遠近判定の判定結果に基づいて、遠距離離脱エリア、近距離離脱エリア、近距離接近エリア、遠距離接近エリアのいずれのエリアに属するかを判定するエリア判定を行うエリア判定部と、無線リーダ装置との通信が失敗したと判定された場合に、エリア判定の判定結果に基づいて、エリアごとに定められた優先度に応じて、応答信号を再送する再送タイミングを制御する再送タイミング制御部と、を備え、遠距離離脱エリアの優先度は最も高い第１優先度であり、近距離離脱エリアの優先度は第１優先度より低い第２優先度であり、近距離接近エリアの優先度は第２優先度より低い第３優先度であり、遠距離接近エリアの優先度は第３優先度より低い第４優先度である構成を有している。 The wireless communication system of the present invention is a wireless communication system including a wireless tag device and a wireless reader device, wherein the wireless tag device includes a receiving unit that receives a response request signal transmitted from the wireless reader device, and a response request A reception strength measurement unit that measures the reception strength of the signal, a communication success / failure determination unit that determines whether or not the response signal transmitted as a response to the response request signal is received by the wireless reader device and communication with the wireless reader device is successful. Based on the reception strength of the previous response request signal and the reception strength of the current response request signal, when the reception strength is increased, it is determined as approaching, and when the reception strength is decreased, it is determined as leaving. Based on the movement determination unit that performs the movement determination to be determined and the reception strength of the current response request signal, if the reception strength is equal to or greater than a predetermined threshold, it is determined as a short distance, and the reception strength is less than the threshold In this case, a distance determination unit that performs a distance determination to determine a long distance, and a long distance departure area, a short distance departure area, a short distance approach area, or a long distance approach area based on the determination result of the movement determination and the distance determination. Priority determined for each area based on the determination result of the area determination when it is determined that the communication between the area determination unit for determining whether to belong to the area and the communication with the wireless reader device has failed And a retransmission timing control unit for controlling a retransmission timing for retransmitting the response signal. The priority of the long-distance leaving area is the highest priority, and the priority of the short-distance leaving area is the first. The second priority is lower than the priority, the priority of the short-distance approaching area is the third priority lower than the second priority, and the priority of the long-distance approaching area is lower than the third priority. The structure The has.
　このシステムによっても、上記と同様に、無線タグ装置側で、今後の再送の機会の多寡に応じて適切な優先度を設定することができ、その優先度に基づいて再送タイミングを適切に制御することができる。 Also in this system, as described above, an appropriate priority can be set on the wireless tag device side according to the number of future retransmission opportunities, and the retransmission timing is appropriately controlled based on the priority. be able to.
　本発明の再送制御方法は、無線通信システムで用いられる再送制御方法であって、無線リーダ装置から送信される応答要求信号を無線タグ装置で受信し、無線タグ装置において、応答要求信号の受信強度を測定し、応答要求信号に対する応答として送信した応答信号が無線リーダ装置で受け付けられて無線リーダ装置との通信が成功したか否か判定し、以前の応答要求信号の受信強度と今回の応答要求信号の受信強度とに基づいて、受信強度が増加している場合には接近と判定し、受信強度が減少している場合には離脱と判定する移動判定を行い、今回の応答要求信号の受信強度に基づいて、受信強度が所定の閾値以上である場合には近距離と判定し、受信強度が閾値未満である場合には遠距離と判定する遠近判定を行い、移動判定と遠近判定の判定結果に基づいて、遠距離離脱エリア、近距離離脱エリア、近距離接近エリア、遠距離接近エリアのいずれのエリアに属するかを判定するエリア判定を行い、無線リーダ装置との通信が失敗したと判定された場合に、エリア判定の判定結果に基づいて、エリアごとに定められた優先度に応じて、応答信号を再送する再送タイミングを制御するものであり、遠距離離脱エリアの優先度は最も高い第１優先度であり、近距離離脱エリアの優先度は第１優先度より低い第２優先度であり、近距離接近エリアの優先度は第２優先度より低い第３優先度であり、遠距離接近エリアの優先度は第３優先度より低い第４優先度である。 The retransmission control method of the present invention is a retransmission control method used in a wireless communication system, wherein a response request signal transmitted from a wireless reader device is received by the wireless tag device, and the reception strength of the response request signal is received by the wireless tag device. The response signal transmitted as a response to the response request signal is received by the wireless reader device, and it is determined whether or not the communication with the wireless reader device is successful. The reception strength of the previous response request signal and the current response request are determined. Based on the reception strength of the signal, if the reception strength is increased, it is determined to be approaching, and if the reception strength is decreased, a movement determination is made to determine that it is leaving. Based on the strength, if the received strength is equal to or greater than a predetermined threshold, the distance is determined to be near, and if the received strength is less than the threshold, the distance is determined to be a long distance. Communication with the wireless reader device fails due to area determination that determines whether it belongs to a long-distance leaving area, short-distance leaving area, short-distance approaching area, or long-distance approaching area If it is determined that the response signal has been determined, the retransmission timing for retransmitting the response signal is controlled according to the priority determined for each area based on the determination result of the area determination. Is the highest first priority, the priority of the short distance departure area is the second priority lower than the first priority, and the priority of the short distance approach area is the third priority lower than the second priority. Yes, the priority of the long-distance approaching area is the fourth priority that is lower than the third priority.
　この方法によっても、上記と同様に、無線タグ装置側で、今後の再送の機会の多寡に応じて適切な優先度を設定することができ、その優先度に基づいて再送タイミングを適切に制御することができる。 Also in this method, as described above, an appropriate priority can be set on the wireless tag device side in accordance with the number of future retransmission opportunities, and the retransmission timing is appropriately controlled based on the priority. be able to.
　本発明によれば、無線リーダ装置との通信が失敗したときに、今後の再送の機会の多寡に応じて適切な優先度を設定し、その優先度に基づいて適切な再送制御をすることができる。 According to the present invention, when communication with the wireless reader device fails, an appropriate priority is set according to the number of future retransmission opportunities, and appropriate retransmission control is performed based on the priority. it can.
　以下、本発明の実施の形態の無線タグ装置および無線通信システムについて、図面を用いて説明する。本実施の形態では、高速道路などの構造物の点検や監視のためのセンサーネットワーク等に適用される場合を例示する。 Hereinafter, a wireless tag device and a wireless communication system according to an embodiment of the present invention will be described with reference to the drawings. In this embodiment, a case where the present invention is applied to a sensor network or the like for inspection and monitoring of a structure such as a highway is illustrated.
（第１の実施の形態）
　本発明の第１の実施の形態の無線タグ装置および無線通信システムの構成を、図面を参照して説明する。図１は、本実施の形態の無線通信システムのブロック図であり、図２は、本実施の形態の無線通信システムの説明図である。図１および図２に示すように、無線通信システム１は、無線タグ装置２と無線リーダ装置３で構成されている。 (First embodiment)
A configuration of the wireless tag device and the wireless communication system according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of the wireless communication system of the present embodiment, and FIG. 2 is an explanatory diagram of the wireless communication system of the present embodiment. As shown in FIGS. 1 and 2, the wireless communication system 1 includes a wireless tag device 2 and a wireless reader device 3.
　無線タグ装置２は、高速道路の道路脇などに設置され、センサ４に接続されている。センサ４としては、種々のセンサを利用することができる。図１に示すように、無線タグ装置２には、センサ４から測定データが入力されるセンサインターフェース５（センサＩ／Ｆ）が設けられている。センサ４の測定データは、無線リーダ装置３に送信されるまでの間、未送信データとして、記憶部６に記憶される。 The wireless tag device 2 is installed on the side of a highway or the like and connected to a sensor 4. Various sensors can be used as the sensor 4. As shown in FIG. 1, the wireless tag device 2 is provided with a sensor interface 5 (sensor I / F) to which measurement data is input from the sensor 4. The measurement data of the sensor 4 is stored in the storage unit 6 as untransmitted data until it is transmitted to the wireless reader device 3.
　また、無線タグ装置２は、無線リーダ装置３から送信される信号を受信する受信部７と、無線リーダ装置３へ信号を送信する送信部８を備えている。受信部７では、無線リーダ装置３から送信される応答要求信号（ビーコン信号）などが受信される。送信部８からは、応答要求信号に対する応答信号（ＡＣＫ信号）などが送信される。受信部７で受信したデータ（受信データ）は、制御部９へ送られる。 Further, the wireless tag device 2 includes a receiving unit 7 that receives a signal transmitted from the wireless reader device 3 and a transmitting unit 8 that transmits a signal to the wireless reader device 3. The reception unit 7 receives a response request signal (beacon signal) transmitted from the wireless reader device 3. From the transmission unit 8, a response signal (ACK signal) to the response request signal is transmitted. Data (received data) received by the receiving unit 7 is sent to the control unit 9.
　また、無線タグ装置２には、無線リーダ装置３からビーコン信号を受信したときに、その受信電界強度（ＲＳＳＩ）を測定する受信強度測定部１０が備えられている。受信強度測定部１０で測定したＲＳＳＩのデータは、制御部９へ送られる。さらに、制御部９へ送られたＲＳＳＩのデータは、記憶部６へ送られて記憶される。 In addition, the wireless tag device 2 is provided with a reception strength measuring unit 10 that measures the received electric field strength (RSSI) when a beacon signal is received from the wireless reader device 3. The RSSI data measured by the reception intensity measurement unit 10 is sent to the control unit 9. Further, the RSSI data sent to the control unit 9 is sent to the storage unit 6 and stored therein.
　制御部９は、例えばＣＰＵなどで構成され、無線タグ装置２の装置全体の制御を行う機能を備えている。制御部９へ送られた受信データは、通信成否判定部１１へ送られる。通信成否判定部１１は、ビーコン信号に対する応答として無線リーダ装置３へ送信したＡＣＫ信号が、無線リーダ装置３で受け付けられたか否か、すなわち、無線リーダ装置３との通信が成功したか否かを、受信データに基づいて判定する機能を備えている。無線リーダ装置３との通信が成功し、記憶部６に記憶されている未送信データの送信が完了すると、記憶部６から未送信データが削除される。 The control unit 9 is composed of, for example, a CPU and has a function of controlling the entire device of the wireless tag device 2. The received data sent to the control unit 9 is sent to the communication success / failure determination unit 11. The communication success / failure determination unit 11 determines whether or not the ACK signal transmitted to the wireless reader device 3 as a response to the beacon signal has been received by the wireless reader device 3, that is, whether or not communication with the wireless reader device 3 has been successful. A function of determining based on received data is provided. When communication with the wireless reader device 3 is successful and transmission of untransmitted data stored in the storage unit 6 is completed, the untransmitted data is deleted from the storage unit 6.
　また、無線タグ装置２には、ＲＳＳＩに基づいた各種の判定（移動判定、遠近判定、エリア判定）を行う判定処理部１２が備えられている。ここで、図３を参照しながら、これらの判定について詳しく説明する。 In addition, the wireless tag device 2 includes a determination processing unit 12 that performs various determinations based on RSSI (movement determination, perspective determination, area determination). Here, these determinations will be described in detail with reference to FIG.
　図３に示すように、移動判定では、以前に受信したビーコン信号のＲＳＳＩ（記憶部６に記憶されている）と今回受信したビーコン信号のＲＳＳＩに基づいて、ＲＳＳＩが増加している場合には「接近（近づく）」と判定し、ＲＳＳＩが減少している場合には「離脱（遠のく）」と判定する。 As shown in FIG. 3, in the movement determination, when the RSSI is increased based on the RSSI (stored in the storage unit 6) of the beacon signal received previously and the RSSI of the beacon signal received this time, It determines with "approaching (approaching)", and when RSSI is decreasing, it determines with "leaving (distant)".
　また、遠近判定では、今回受信したビーコン信号のＲＳＳＩと閾値を比較して、ＲＳＳＩが閾値以上である場合には「近距離（近い）」と判定し、ＲＳＳＩが閾値未満である場合には「遠距離（遠い）」と判定する。 In the perspective determination, the RSSI of the beacon signal received this time is compared with the threshold, and when the RSSI is equal to or greater than the threshold, it is determined as “near distance (near)”, and when the RSSI is less than the threshold, “ It is determined as “far (far)”.
　そして、エリア判定では、上記の移動判定と遠近判定の判定結果に基づいて、タグ装置が「遠距離離脱エリア」「近距離離脱エリア」「近距離接近エリア」「遠距離接近エリア」のいずれのエリアに属するかを判定する。これらのエリアには、それぞれ優先度が設定されている。この場合、「遠距離離脱エリア：最高（即座に再送）」「近距離離脱エリア：高（早く再送）」「近距離接近エリア：中（やや早く再送）」「遠距離接近エリア：低（ゆっくり再送）」という優先度が設定されている。 In the area determination, based on the determination result of the above movement determination and perspective determination, the tag device is any of “long distance departure area”, “short distance departure area”, “short distance approach area”, and “far distance approach area”. Determine if it belongs to the area. Priorities are set for these areas. In this case, “Long distance departure area: Highest (Immediately retransmit)” “Near distance departure area: High (Resend early)” “Near distance approach area: Middle (Slightly early retransmission)” “Long distance approach area: Low (slowly "Resend") is set.
　図１に戻って、無線タグ装置２の構成の説明を続ける。無線タグ装置２には、送信タイミング制御部１３が備えられている。送信タイミング制御部１３は、ビーコン信号に対するＡＣＫ信号を送信するタイミング（どのタイムスロットで送信するか）を決定する機能を備えている。この無線タグ装置２には、乱数生成部１４が備えられている。乱数生成部１４では、ランダム制御を行うための乱数が生成される。送信タイミング制御は、乱数生成部１４で生成された乱数に基づいて、ＡＣＫ信号を送信するタイムスロットをランダムに割り当てるランダム制御が行われる。 Referring back to FIG. 1, the description of the configuration of the wireless tag device 2 will be continued. The wireless tag device 2 includes a transmission timing control unit 13. The transmission timing control unit 13 has a function of determining a timing (in which time slot to transmit) an ACK signal for a beacon signal. The wireless tag device 2 includes a random number generator 14. The random number generator 14 generates a random number for performing random control. The transmission timing control is a random control in which a time slot for transmitting an ACK signal is randomly assigned based on the random number generated by the random number generation unit 14.
　また、送信タイミング制御部１３は、無線リーダ装置３との通信に失敗した場合に、エリア判定の判定結果に基づいて、そのエリアの優先度に応じてＡＣＫ信号を再送する再送制御を行う機能を備えている。この場合、優先度が高いほど１フレーム期間あたりの再送回数（再送頻度）を多くするように、ＡＣＫ信号の再送タイミングが制御される。 Further, the transmission timing control unit 13 has a function of performing retransmission control for retransmitting an ACK signal according to the priority of the area based on the determination result of the area determination when the communication with the wireless reader device 3 fails. I have. In this case, the retransmission timing of the ACK signal is controlled so that the higher the priority is, the greater the number of retransmissions per frame period (retransmission frequency) is.
　ここで、図４を参照して、ＡＣＫ信号の再送タイミングの制御について、詳しく説明しておく。図４には、無線フレーム構成の一例が示される。図４に示すように、例えば、１フレームが、２つのユニット（第１ユニットおよび第２ユニット）で構成され、１つのユニットが４５個のサブフレーム（第１サブフレーム～第４５サブフレーム）で構成され、１フレームに、ｎ個のタイムスロットが含まれているとする。 Here, the control of the retransmission timing of the ACK signal will be described in detail with reference to FIG. FIG. 4 shows an example of a radio frame configuration. As shown in FIG. 4, for example, one frame is composed of two units (first unit and second unit), and one unit is composed of 45 subframes (first subframe to 45th subframe). It is assumed that n time slots are included in one frame.
　この場合、第１ユニットで無線リーダ装置３との通信が失敗したとすると、遠距離離脱エリアであれば、第２ユニットの４５個のサブフレームすべて（第１サブフレーム～第４５サブフレーム）で応答信号を再送し、近距離離脱エリアであれば、第２ユニットの３０個のサブフレーム（例えば、第１６サブフレーム～第４５サブフレーム）で応答信号を再送する。また、近距離接近エリアであれば、第２ユニットの２０個のサブフレーム（例えば、第２６サブフレーム～第４５サブフレーム）で応答信号を再送し、遠距離接近エリアであれば、第２ユニットの１０個のサブフレーム（例えば、第３６サブフレーム～第４５サブフレーム）で応答信号を再送する。 In this case, assuming that communication with the wireless reader device 3 has failed in the first unit, all 45 subframes (first subframe to 45th subframe) of the second unit are within the long-distance leaving area. The response signal is retransmitted, and if it is a short distance departure area, the response signal is retransmitted in 30 subframes (for example, the 16th subframe to the 45th subframe) of the second unit. If it is a short-distance approach area, the response signal is retransmitted in 20 subframes (for example, the 26th to 45th subframes) of the second unit. If it is a long-distance approach area, the second unit The response signal is retransmitted in 10 subframes (for example, the 36th to 45th subframes).
　無線リーダ装置３は、無線タグ装置２へ信号を送信する送信部１５と、無線タグ装置２からの信号を受信する受信部１６を備えている。送信部１５からは、無線タグ装置２へのビーコン信号などが送信される。受信部１６では、無線タグ装置２から送信されるＡＣＫ信号などが受信される。受信部１６で受信したデータ（受信データ）は、制御部１７へ送られる。さらに、制御部１７へ送られたデータは、記憶部１８へ送られて記憶される。 The wireless reader device 3 includes a transmission unit 15 that transmits a signal to the wireless tag device 2 and a reception unit 16 that receives a signal from the wireless tag device 2. A beacon signal or the like to the wireless tag device 2 is transmitted from the transmission unit 15. The receiving unit 16 receives an ACK signal transmitted from the wireless tag device 2. Data (received data) received by the receiving unit 16 is sent to the control unit 17. Further, the data sent to the control unit 17 is sent to the storage unit 18 and stored therein.
　以上のように構成された無線通信システム１について、図５のシーケンス図を参照してその動作を説明する。ここでは、本発明の特徴的な動作である再送制御を中心に説明する。 The operation of the wireless communication system 1 configured as described above will be described with reference to the sequence diagram of FIG. Here, the retransmission control which is a characteristic operation of the present invention will be mainly described.
　図５に示すように、本実施の形態の無線通信システム１では、まず、第１ユニットの第０タイムロット（ＴＳ０）で、無線リーダ装置３から無線タグ装置２へブロードキャストビーコンが送信される。この場合、無線リーダ装置３の通信可能エリア内に、二つの無線タグ装置２（タグＡ、タグＢ）が存在していたとする。ブロードキャストビーコンは、二つの無線タグ装置２（タグＡ、タグＢ）で受信され、それぞれの無線タグ装置２でＲＳＳＩの測定が行われる。 As shown in FIG. 5, in the wireless communication system 1 according to the present embodiment, first, a broadcast beacon is transmitted from the wireless reader device 3 to the wireless tag device 2 in the 0th time lot (TS0) of the first unit. In this case, it is assumed that two wireless tag devices 2 (tag A and tag B) exist in the communicable area of the wireless reader device 3. The broadcast beacon is received by the two wireless tag devices 2 (tag A and tag B), and the RSSI is measured by each of the wireless tag devices 2.
　同様に、第１タイムスロット（ＴＳ１）でも、無線リーダ装置３から無線タグ装置２へブロードキャストビーコンが送信される。このブロードキャストビーコンも、二つの無線タグ装置２（タグＡ、タグＢ）でそれぞれ受信され、ＲＳＳＩの測定が行われる。 Similarly, a broadcast beacon is transmitted from the wireless reader device 3 to the wireless tag device 2 also in the first time slot (TS1). This broadcast beacon is also received by each of the two wireless tag devices 2 (tag A and tag B), and RSSI is measured.
　第２タイムスロット（ＴＳ２）では、二つの無線タグ装置２（タグＡ、タグＢ）からブロードキャストビーコンに対する応答としてＡＣＫ信号が送信される。この場合、二つの無線タグ装置２から同じタイミングでＡＣＫ信号が送信されるので、ＡＣＫ信号の受信時に衝突（コリジョン）が発生する。無線リーダ装置３は、一方のＡＣＫ信号（タグＡからのＡＣＫ信号）のみを受信し、他方のＡＣＫ信号（タグＢからのＡＣＫ信号）を破棄する。 In the second time slot (TS2), an ACK signal is transmitted as a response to the broadcast beacon from the two wireless tag devices 2 (tag A and tag B). In this case, since the ACK signal is transmitted from the two RFID tag apparatuses 2 at the same timing, a collision (collision) occurs when the ACK signal is received. The wireless reader device 3 receives only one ACK signal (ACK signal from tag A) and discards the other ACK signal (ACK signal from tag B).
　そうすると、第３タイムスロット（ＴＳ３）で、無線タグ装置２からのＡＣＫ信号に対する応答として、無線リーダ装置３から「タグＡとの通信に成功した」ことを通知するユニキャストビーコン信号が送信される。これにより、一方の無線タグ装置２（タグＡ）は、無線リーダ装置３との通信に成功したことを認識し、他方の無線タグ装置２（タグＢ）は、無線リーダ装置３との通信に失敗したことを認識する。無線リーダ装置３との通信に成功した無線タグ装置２（タグＡ）は、消費電力を抑えるためのセービング制御を行う。 Then, in the third time slot (TS3), as a response to the ACK signal from the wireless tag device 2, a unicast beacon signal notifying that “communication with the tag A is successful” is transmitted from the wireless reader device 3. . Thereby, one wireless tag device 2 (tag A) recognizes that the communication with the wireless reader device 3 is successful, and the other wireless tag device 2 (tag B) communicates with the wireless reader device 3. Recognize the failure. The wireless tag device 2 (tag A) that has succeeded in communication with the wireless reader device 3 performs saving control to reduce power consumption.
　第５タイムスロット（ＴＳ５）と第７タイムスロット（ＴＳ７）で、無線リーダ装置３からブロードキャストビーコン信号が送信される。このビーコン信号は、セービング制御が行われていない（無線リーダ装置３との通信に失敗した）無線タグ装置２（タグＢ）で受信され、ＲＳＳＩの測定が行われる。 The broadcast beacon signal is transmitted from the wireless reader device 3 in the fifth time slot (TS5) and the seventh time slot (TS7). This beacon signal is received by the wireless tag device 2 (tag B) that is not subjected to saving control (communication with the wireless reader device 3 has failed), and RSSI is measured.
　その後、無線タグ装置２（タグＢ）では、ＴＳ７で受信したブロードキャストビーコン信号（直近に受信したビーコン信号）のＲＳＳＩと閾値とを比較して遠近判定が行われ、また、ＴＳ０で受信したブロードキャストビーコン信号（最初に受信したビーコン信号）とＴＳ７で受信したブロードキャストビーコン信号（直近に受信したビーコン信号）からＲＳＳＩの増減に基く移動判定が行われる。そして、遠近判定と移動判定の判定結果に基づいてエリア判定が行われ、エリア判定の判定結果に基づいて、そのエリアの優先度に応じた再送タイミング（例えば、第２ユニットの第ｎ－１タイムスロット（ＴＳｎ－１）など）が決定される。その後、無線タグ装置２（タグＢ）でも、消費電力を抑えるためのセービング制御が行われる。 Thereafter, the RFID tag device 2 (tag B) compares the RSSI of the broadcast beacon signal (the most recently received beacon signal) received at TS7 with a threshold value, and determines the perspective, and the broadcast beacon received at TS0. The movement determination based on the increase / decrease of RSSI is performed from the signal (beacon signal received first) and the broadcast beacon signal received by TS7 (beacon signal received most recently). Then, the area determination is performed based on the determination results of the perspective determination and the movement determination, and based on the determination result of the area determination, the retransmission timing according to the priority of the area (for example, the n-1th time of the second unit) Slot (TSn-1), etc.) is determined. Thereafter, the wireless tag device 2 (tag B) also performs saving control for suppressing power consumption.
　そして、無線タグ装置２（タグＢ）は、第２ユニットの第ｎ－２タイムスロットで無線リーダ装置３からのブロードキャストビーコン信号を受信すると、次の第ｎ－１タイムスロット（ＴＳｎ－１）でＡＣＫ信号を無線リーダ装置３に再送する。無線リーダ装置３は、無線タグ装置２（タグＢ）からのＡＣＫ信号を受信すると、「タグＢとの通信に成功した」ことを通知するユニキャストビーコン信号を送信する。これにより、無線タグ装置２（タグＢ）は、無線リーダ装置３との通信に成功したことを認識する。無線リーダ装置３との通信に成功した無線タグ装置２（タグＢ）は、消費電力を抑えるためのセービング制御を行う。 When the wireless tag device 2 (tag B) receives the broadcast beacon signal from the wireless reader device 3 in the n-2 time slot of the second unit, the wireless tag device 2 (tag B) uses the next n-1 time slot (TSn-1). The ACK signal is retransmitted to the wireless reader device 3. When the wireless reader device 3 receives the ACK signal from the wireless tag device 2 (tag B), the wireless reader device 3 transmits a unicast beacon signal notifying that “communication with the tag B was successful”. Thereby, the wireless tag device 2 (tag B) recognizes that the communication with the wireless reader device 3 is successful. The wireless tag device 2 (tag B) that has successfully communicated with the wireless reader device 3 performs a saving control for suppressing power consumption.
　このような第１の実施の形態の無線タグ装置２によれば、無線リーダ装置３との通信が失敗したときに、今後の再送の機会の多寡に応じて適切な優先度を設定し、その優先度に基づいて適切な再送制御をすることができる。 According to the wireless tag device 2 of the first embodiment as described above, when communication with the wireless reader device 3 fails, an appropriate priority is set according to the number of future retransmission opportunities, Appropriate retransmission control can be performed based on the priority.
　すなわち、本実施の形態では、無線リーダ装置３からのビーコン信号のＲＳＳＩに基づいて移動判定と遠近判定が行われ、無線タグ装置２の属するエリアが「遠距離離脱エリア」「近距離離脱エリア」「近距離接近エリア」「遠距離接近エリア」のいずれであるかが判定される。無線リーダ装置３との通信が失敗したと判定されると、各エリアごとに定められた優先度に応じて、ＡＣＫ信号を再送する再送タイミングが制御される。 That is, in the present embodiment, the movement determination and the distance determination are performed based on the RSSI of the beacon signal from the wireless reader device 3, and the area to which the wireless tag device 2 belongs is “long distance departure area” “short distance departure area”. It is determined whether it is a “short-distance approaching area” or a “far-distance approaching area”. If it is determined that the communication with the wireless reader device 3 has failed, the retransmission timing for retransmitting the ACK signal is controlled according to the priority determined for each area.
　例えば、遠距離離脱エリアは、無線リーダ装置３と無線タグ装置２が「遠距離」にあり互いに「離脱」している（遠ざかっている）ため、今後の再送の機会が最も少ない（間もなく通信可能エリアの圏外に出てしまう）と考えられるので、最も高い優先度（第１優先度：最高）に設定され、最優先で応答信号が再送される。また、近距離離脱エリアは、無線リーダ装置３と無線タグ装置２が「近距離」にあるものの互いに「離脱」している（遠ざかっている）ため、今後の再送の機会が遠距離離脱エリアの次に少ないと考えられるので、その次に高い優先度（第２優先度：高）に設定される。さらに、近距離接近エリアは、無線リーダ装置３と無線タグ装置２が「近距離」にあり互いに「接近」している（近づいている）ため、近距離離脱エリアより再送の機会が多いと考えられるので、その次の優先度（第３優先度：中）に設定される。そして、遠距離接近エリアは、無線リーダ装置３と無線タグ装置２が「遠距離」にあり互いに「接近」している（近づいている）ため、今後の再送の機会が最も多い（しばらく通信可能エリアの圏内に滞在する）と考えられるため、最も低い優先度（第４優先度：低）に設定される。 For example, in the long-distance leaving area, the wireless reader device 3 and the wireless tag device 2 are “far away” and “separated” from each other (away from each other), so there are few opportunities for future retransmission (communication is possible soon) Therefore, the highest priority (first priority: highest) is set, and the response signal is retransmitted with the highest priority. In addition, since the wireless reader device 3 and the wireless tag device 2 are “near distance” in the short-distance leaving area, they are “separated” (distant) from each other. Since it is considered to be the next smallest, the next highest priority (second priority: high) is set. Further, in the short-distance approach area, the wireless reader device 3 and the wireless tag device 2 are “near-distance” and “close” to each other. Therefore, the next priority (third priority: medium) is set. In the long-distance approach area, the wireless reader device 3 and the wireless tag device 2 are “far” and are “close” to each other (approaching). Therefore, the lowest priority (fourth priority: low) is set.
　このように、本実施の形態の無線通信システム１によれば、無線タグ装置２側で、今後の再送の機会の多寡に応じて適切な優先度を設定することができ、その優先度に基づいて再送タイミングを適切に制御することができる。 As described above, according to the wireless communication system 1 of the present embodiment, an appropriate priority can be set on the wireless tag device 2 side according to the number of future retransmission opportunities, and based on the priority. Thus, the retransmission timing can be appropriately controlled.
　また、本実施の形態では、優先度が高いほど所定期間（例えば１フレーム）あたりの再送回数が多くなるように、応答信号の再送タイミングの制御（再送制御）が行われる。 In the present embodiment, control of retransmission timing of response signals (retransmission control) is performed so that the higher the priority, the greater the number of retransmissions per predetermined period (for example, one frame).
　例えば、図４に示すように、１つのフレームが、２つのユニット（第１ユニットおよび第２ユニット）で構成され、１つのユニットが４５個のサブフレーム（第１サブフレーム～第４５サブフレーム）で構成されている場合に、第１ユニットで無線リーダ装置３との通信が失敗したとする。その場合、遠距離離脱エリアであれば、第２ユニットの４５個のサブフレームすべて（第１サブフレーム～第４５サブフレーム）で応答信号を再送し、近距離離脱エリアであれば、第２ユニットの３０個のサブフレーム（例えば、第１６サブフレーム～第４５サブフレーム）で応答信号を再送する。また、近距離接近エリアであれば、第２ユニットの２０個のサブフレーム（例えば、第２６サブフレーム～第４５サブフレーム）で応答信号を再送し、遠距離接近エリアであれば、第２ユニットの１０個のサブフレーム（例えば、第３６サブフレーム～第４５サブフレーム）で応答信号を再送する。 For example, as shown in FIG. 4, one frame is composed of two units (first unit and second unit), and one unit has 45 subframes (first subframe to 45th subframe). Suppose that communication with the wireless reader device 3 has failed in the first unit. In that case, if it is a long distance departure area, the response signal is retransmitted in all 45 subframes (first subframe to 45th subframe) of the second unit, and if it is a short distance departure area, the second unit The response signal is retransmitted in 30 subframes (for example, the 16th subframe to the 45th subframe). If it is a short-distance approach area, the response signal is retransmitted in 20 subframes (for example, the 26th to 45th subframes) of the second unit. If it is a long-distance approach area, the second unit The response signal is retransmitted in 10 subframes (for example, the 36th to 45th subframes).
　このように、本実施の形態によれば、今後の再送の機会の多寡に応じた再送回数（再送頻度）となるように、再送タイミングを適切に制御することができる。 Thus, according to the present embodiment, it is possible to appropriately control the retransmission timing so that the number of retransmissions (retransmission frequency) according to the number of future retransmission opportunities can be achieved.
（第２の実施の形態）
　次に、本発明の第２の実施の形態の無線タグ装置２について説明する。ここでは、第２の実施の形態の無線タグ装置２が、第１の実施の形態と相違する点を中心に説明する。ここで特に言及しない限り、本実施の形態の構成および動作は、第１の実施の形態と同様である。 (Second Embodiment)
Next, the wireless tag device 2 according to the second embodiment of the present invention will be described. Here, the wireless tag device 2 according to the second embodiment will be described focusing on differences from the first embodiment. Unless otherwise specified, the configuration and operation of the present embodiment are the same as those of the first embodiment.
　図６は、本実施の形態の無線通信システム１のブロック図である。図６に示すように、本実施の形態の無線タグ装置２には、事前送信制御部１９が追加されている。事前送信制御部１９は、遠近判定で「遠距離」であると判定された場合に、再送制御で決定される再送タイミングより前のタイミングで、ＡＣＫ信号を無線リーダ装置３に事前に送信する制御（事前送信制御）を行う機能を備えている。 FIG. 6 is a block diagram of the wireless communication system 1 of the present embodiment. As shown in FIG. 6, a pre-transmission control unit 19 is added to the wireless tag device 2 of the present embodiment. The pre-transmission control unit 19 performs control to transmit an ACK signal to the wireless reader device 3 in advance at a timing before the retransmission timing determined by the retransmission control when it is determined as “far” in the perspective determination. A function for performing (pre-transmission control) is provided.
　この事前送信制御は、図７に示すように、無線リーダ装置３の通信可能エリアの縁（フリンジ）の部分をかするように無線タグ装置２が通過する場合を想定したものである。すなわち、無線リーダ装置３の通信可能エリアの縁（フリンジ）の部分をかするように無線タグ装置２が通過する場合には、今後の再送の機会が最も少ない（間もなく通信可能エリアの圏外に出てしまう）と考えられるため、再送制御の送信タイミングより前に、ＡＣＫ信号を送信する。 This pre-transmission control assumes a case where the wireless tag device 2 passes so as to cover the edge (fringe) of the communicable area of the wireless reader device 3 as shown in FIG. That is, when the wireless tag device 2 passes so as to cover the edge (fringe) of the communicable area of the wireless reader device 3, there is the least chance of future retransmission (coming soon out of the communicable area). Therefore, the ACK signal is transmitted before the retransmission control transmission timing.
　図８は、無線フレーム構成の一例を示す図である。図８に示すように、例えば、１つのフレームが、８つのユニット（第１ユニット～第８ユニット）で構成され、後半のユニット（第５ユニット～第８ユニット）で、第１の実施形態と同様の再送制御が行われるとする。この場合、事前送信制御は、前半のユニット（例えば、第２ユニットと第４ユニット）で行われる。 FIG. 8 is a diagram illustrating an example of a radio frame configuration. As shown in FIG. 8, for example, one frame is composed of eight units (first unit to eighth unit), and the second half unit (fifth unit to eighth unit) is the same as in the first embodiment. Assume that similar retransmission control is performed. In this case, the pre-transmission control is performed by the first half units (for example, the second unit and the fourth unit).
　ここで、本実施の形態の無線通信システム１で行われる事前送信制御を、図９のシーケンス図を参照して詳しく説明する。 Here, the advance transmission control performed in the wireless communication system 1 of the present embodiment will be described in detail with reference to the sequence diagram of FIG.
　図９に示すように、本実施の形態の無線通信システム１では、まず、第１ユニットの第０タイムロット（ＴＳ０）と第１タイムスロット（ＴＳ１）で、無線リーダ装置３から無線タグ装置２へブロードキャストビーコンが送信される。この場合も、無線リーダ装置３の通信可能エリア内に、二つの無線タグ装置２（タグＡ、タグＢ）が存在していたとする。ブロードキャストビーコンは、二つの無線タグ装置２（タグＡ、タグＢ）で受信され、それぞれの無線タグ装置２でＲＳＳＩの測定が行われる。 As shown in FIG. 9, in the wireless communication system 1 according to the present embodiment, first, the wireless reader device 3 to the wireless tag device 2 in the 0th time lot (TS0) and the first time slot (TS1) of the first unit. A broadcast beacon is transmitted. Also in this case, it is assumed that there are two wireless tag devices 2 (tag A and tag B) in the communicable area of the wireless reader device 3. The broadcast beacon is received by the two wireless tag devices 2 (tag A and tag B), and the RSSI is measured by each of the wireless tag devices 2.
　第２タイムスロット（ＴＳ２）では、二つの無線タグ装置２（タグＡ、タグＢ）からブロードキャストビーコンに対する応答としてＡＣＫ信号が送信される。この場合にも、二つの無線タグ装置２から同じタイミングでＡＣＫ信号が送信されるので、ＡＣＫ信号の受信時に衝突（コリジョン）が発生する。無線リーダ装置３は、一方のＡＣＫ信号（タグＡからのＡＣＫ信号）のみを受信し、他方のＡＣＫ信号（タグＢからのＡＣＫ信号）を破棄する。 In the second time slot (TS2), an ACK signal is transmitted as a response to the broadcast beacon from the two wireless tag devices 2 (tag A and tag B). Also in this case, since the ACK signals are transmitted from the two RFID tag apparatuses 2 at the same timing, a collision (collision) occurs when the ACK signals are received. The wireless reader device 3 receives only one ACK signal (ACK signal from tag A) and discards the other ACK signal (ACK signal from tag B).
　そうすると、第３タイムスロット（ＴＳ３）で、無線タグ装置２からのＡＣＫ信号に対する応答として、無線リーダ装置３から「タグＡとの通信に成功した」ことを通知するユニキャストビーコン信号が送信される。これにより、一方の無線タグ装置２（タグＡ）は、無線リーダ装置３との通信に成功したことを認識し、他方の無線タグ装置２（タグＢ）は、無線リーダ装置３との通信に失敗したことを認識する。無線リーダ装置３との通信に成功した無線タグ装置２（タグＡ）は、消費電力を抑えるためのセービング制御を行う。 Then, in the third time slot (TS3), as a response to the ACK signal from the wireless tag device 2, a unicast beacon signal notifying that “communication with the tag A is successful” is transmitted from the wireless reader device 3. . Thereby, one wireless tag device 2 (tag A) recognizes that the communication with the wireless reader device 3 is successful, and the other wireless tag device 2 (tag B) communicates with the wireless reader device 3. Recognize the failure. The wireless tag device 2 (tag A) that has succeeded in communication with the wireless reader device 3 performs saving control to reduce power consumption.
　第５タイムスロット（ＴＳ５）で、無線リーダ装置３からブロードキャストビーコン信号が送信されると、このビーコン信号は、セービング制御が行われていない（無線リーダ装置３との通信に失敗した）無線タグ装置２（タグＢ）で受信され、ＲＳＳＩの測定が行われる。 When a broadcast beacon signal is transmitted from the wireless reader device 3 in the fifth time slot (TS5), this beacon signal is not subjected to saving control (communication with the wireless reader device 3 has failed). 2 (tag B), and RSSI is measured.
　この場合、無線タグ装置２（タグＢ）では、ＴＳ５で受信したブロードキャストビーコン信号（直近に受信したビーコン信号）のＲＳＳＩと閾値とを比較して遠近判定が行われ、事前送信を行う送信タイミング（例えば、第２ユニットの第ｍ－１タイムスロット（ＴＳｍ－１）など）が決定される。その後、無線タグ装置２（タグＢ）でも、消費電力を抑えるためのセービング制御が行われる。 In this case, the RFID tag device 2 (tag B) compares the RSSI of the broadcast beacon signal received in TS5 (the recently received beacon signal) with a threshold value, makes a perspective determination, and transmits transmission timing (prior transmission) For example, the (m-1) th time slot (TSm-1) of the second unit is determined. Thereafter, the wireless tag device 2 (tag B) also performs saving control for suppressing power consumption.
　そして、無線タグ装置２（タグＢ）は、第２ユニットの第ｍ－２タイムスロットで無線リーダ装置３からのブロードキャストビーコン信号を受信すると、次の第ｍ－１タイムスロット（ＴＳｍ－１）でＡＣＫ信号を無線リーダ装置３に事前送信する。無線リーダ装置３は、無線タグ装置２（タグＢ）からのＡＣＫ信号を受信すると、「タグＢとの通信に成功した」ことを通知するユニキャストビーコン信号を送信する。これにより、無線タグ装置２（タグＢ）は、無線リーダ装置３との通信に成功したことを認識し、消費電力を抑えるためのセービング制御を行う。 When the wireless tag device 2 (tag B) receives the broadcast beacon signal from the wireless reader device 3 in the m-2 time slot of the second unit, the wireless tag device 2 (tag B) uses the next m-1 time slot (TSm-1). An ACK signal is transmitted to the wireless reader device 3 in advance. When the wireless reader device 3 receives the ACK signal from the wireless tag device 2 (tag B), the wireless reader device 3 transmits a unicast beacon signal notifying that “communication with the tag B was successful”. As a result, the wireless tag device 2 (tag B) recognizes that communication with the wireless reader device 3 has succeeded, and performs saving control to suppress power consumption.
　このような第２の実施の形態の無線タグ装置２によっても、第１の実施の形態と同様の作用効果が奏される。 Also with the wireless tag device 2 according to the second embodiment, the same effects as those of the first embodiment can be obtained.
　その上、本実施の形態では、無線リーダ装置３との通信が失敗したと判定された場合に、遠近判定で遠距離と判定されると、上記の再送制御で決定される再送タイミングより前のタイミングで、ＡＣＫ信号が事前に送信される。例えば、無線リーダ装置３の通信可能エリアの縁（フリンジ）の部分をかするように無線タグ装置２が通過する場合、今後の再送の機会が最も少ない（間もなく通信可能エリアの圏外に出てしまう）と考えられるが、本実施の形態によれば、そのような場合に、再送タイミングより前のタイミングでＡＣＫ信号が事前に再送されるので、無線リーダ装置３との通信の成功率を更に高めることができる。 In addition, in the present embodiment, when it is determined that communication with the wireless reader device 3 has failed, if it is determined that the distance is determined to be a long distance by the distance determination, the time before the retransmission timing determined by the above retransmission control is determined. At the timing, an ACK signal is transmitted in advance. For example, when the wireless tag device 2 passes so as to cover the edge (fringe) of the communicable area of the wireless reader device 3, the chances of future retransmissions are fewest (soon to go out of the communicable area). However, according to the present embodiment, since the ACK signal is retransmitted in advance at a timing before the retransmission timing in such a case, the success rate of communication with the wireless reader device 3 is further increased. be able to.
　以上、本発明の実施の形態を例示により説明したが、本発明の範囲はこれらに限定されるものではなく、請求項に記載された範囲内において目的に応じて変更・変形することが可能である。 The embodiments of the present invention have been described above by way of example, but the scope of the present invention is not limited to these embodiments, and can be changed or modified according to the purpose within the scope of the claims. is there.
　例えば、以上の説明では、無線リーダ装置３が移動し無線タグ装置２が固定されるシステムについて説明したが、本発明の範囲はこれに限定されるものではなく、無線タグ装置２が移動し無線リーダ装置３が固定されるシステムにも利用することができる。 For example, in the above description, the system in which the wireless reader device 3 moves and the wireless tag device 2 is fixed has been described. However, the scope of the present invention is not limited to this, and the wireless tag device 2 moves and wirelessly moves. It can also be used in a system in which the reader device 3 is fixed.
　以上に現時点で考えられる本発明の好適な実施の形態を説明したが、本実施の形態に対して多様な変形が可能なことが理解され、そして、本発明の真実の精神と範囲内にあるそのようなすべての変形を添付の請求の範囲が含むことが意図されている。 Although the presently preferred embodiments of the present invention have been described above, it will be understood that various modifications can be made to the present embodiments and are within the true spirit and scope of the present invention. It is intended that the appended claims include all such variations.
　以上のように、本発明にかかる無線タグ装置は、無線リーダ装置との通信が失敗したときに、今後の再送の機会の多寡に応じて適切な優先度を設定し、その優先度に基づいて適切な再送制御をすることができるという効果を有し、高速道路などの構造物の点検や監視のためのセンサーネットワークに適用され、有用である。 As described above, when the communication with the wireless reader device fails, the wireless tag device according to the present invention sets an appropriate priority according to the number of future retransmission opportunities, and based on the priority. It has the effect of being able to perform appropriate retransmission control, and is useful when applied to a sensor network for inspection and monitoring of structures such as expressways.
　１　無線通信システム
　２　無線タグ装置
　３　無線リーダ装置
　４　センサ
　５　センサインターフェース
　６　記憶部
　７　受信部
　８　送信部
　９　制御部
　１０　受信強度測定部
　１１　通信成否判定部
　１２　判定処理部
　１３　送信タイミング制御部
　１４　乱数生成部
　１５　送信部
　１６　受信部
　１７　制御部
　１８　記憶部
　１９　事前送信制御部 DESCRIPTION OF SYMBOLS 1 Wireless communication system 2 Wireless tag apparatus 3 Wireless reader apparatus 4 Sensor 5 Sensor interface 6 Storage part 7 Reception part 8 Transmission part 9 Control part 10 Reception strength measurement part 11 Communication success / failure determination part 12 Judgment processing part 13 Transmission timing control part 14 Random number Generation unit 15 Transmission unit 16 Reception unit 17 Control unit 18 Storage unit 19 Pre-transmission control unit

Claims (6)

  1. 　無線リーダ装置から送信される応答要求信号を受信する受信部と、
    　前記応答要求信号の受信強度を測定する受信強度測定部と、
    　前記応答要求信号に対する応答として送信した応答信号が前記無線リーダ装置で受け付けられて前記無線リーダ装置との通信が成功したか否か判定する通信成否判定部と、
    　以前の応答要求信号の受信強度と今回の応答要求信号の受信強度とに基づいて、前記受信強度が増加している場合には接近と判定し、前記受信強度が減少している場合には離脱と判定する移動判定を行う移動判定部と、
    　前記今回の応答要求信号の受信強度に基づいて、前記受信強度が所定の閾値以上である場合には近距離と判定し、前記受信強度が前記閾値未満である場合には遠距離と判定する遠近判定を行う遠近判定部と、
    　前記移動判定と前記遠近判定の判定結果に基づいて、遠距離離脱エリア、近距離離脱エリア、近距離接近エリア、遠距離接近エリアのいずれのエリアに属するかを判定するエリア判定を行うエリア判定部と、
    　前記無線リーダ装置との通信が失敗したと判定された場合に、前記エリア判定の判定結果に基づいて、前記エリアごとに定められた優先度に応じて、前記応答信号を再送する再送タイミングを制御する再送タイミング制御部と、
    を備え、
    　前記遠距離離脱エリアの優先度は最も高い第１優先度であり、前記近距離離脱エリアの優先度は前記第１優先度より低い第２優先度であり、前記近距離接近エリアの優先度は前記第２優先度より低い第３優先度であり、前記遠距離接近エリアの優先度は前記第３優先度より低い第４優先度であることを特徴とする無線タグ装置。     A receiving unit for receiving a response request signal transmitted from the wireless reader device;
    A reception intensity measuring unit for measuring the reception intensity of the response request signal;
    A communication success / failure determination unit that determines whether a response signal transmitted as a response to the response request signal is received by the wireless reader device and communication with the wireless reader device is successful;
    Based on the reception strength of the previous response request signal and the reception strength of the current response request signal, when the reception strength is increased, it is determined as approaching, and when the reception strength is decreased, it is detached. A movement determination unit for performing movement determination to determine
    Based on the reception strength of the response request signal this time, when the reception strength is equal to or greater than a predetermined threshold, it is determined as a short distance, and when the reception strength is less than the threshold, it is determined as a long distance A perspective determination unit for performing the determination;
    An area determination unit that performs area determination to determine which of a long distance departure area, a short distance departure area, a short distance approach area, and a long distance approach area based on the determination result of the movement determination and the perspective determination When,
    When it is determined that the communication with the wireless reader device has failed, the retransmission timing for retransmitting the response signal is controlled according to the priority determined for each area based on the determination result of the area determination A retransmission timing control unit,
    With
    The priority of the long-distance leaving area is the highest first priority, the priority of the short-distance leaving area is the second priority lower than the first priority, and the priority of the short-distance approaching area is The wireless tag device according to claim 1, wherein the third priority is lower than the second priority, and the priority of the long-distance approach area is a fourth priority lower than the third priority.
  2. 　前記再送タイミング制御部は、前記優先度が高いほど所定期間あたりの再送回数が多くなるように、前記応答信号の再送タイミングを制御することを特徴とする請求項１に記載の無線タグ装置。 The RFID tag device according to claim 1, wherein the retransmission timing control unit controls the retransmission timing of the response signal so that the higher the priority is, the larger the number of retransmissions per predetermined period is.
  3. 　前記遠近判定で遠距離と判定された場合には、前記再送タイミング制御部で決定される再送タイミングより前のタイミングで、前記応答信号を事前に送信する事前送信制御部を備えたことを特徴とする請求項１に記載の無線タグ装置。 A pre-transmission control unit that transmits the response signal in advance at a timing prior to the retransmission timing determined by the retransmission timing control unit when it is determined that the distance is determined by the distance determination; The wireless tag device according to claim 1.
  4. 　無線タグ装置で用いられる再送制御方法であって、
    　無線リーダ装置から送信される応答要求信号を受信し、
    　前記応答要求信号の受信強度を測定し、
    　前記応答要求信号に対する応答として送信した応答信号が前記無線リーダ装置で受け付けられて前記無線リーダ装置との通信が成功したか否か判定し、
    　以前の応答要求信号の受信強度と今回の応答要求信号の受信強度とに基づいて、前記受信強度が増加している場合には接近と判定し、前記受信強度が減少している場合には離脱と判定する移動判定を行い、
    　前記今回の応答要求信号の受信強度に基づいて、前記受信強度が所定の閾値以上である場合には近距離と判定し、前記受信強度が前記閾値未満である場合には遠距離と判定する遠近判定を行い、
    　前記移動判定と前記遠近判定の判定結果に基づいて、遠距離離脱エリア、近距離離脱エリア、近距離接近エリア、遠距離接近エリアのいずれのエリアに属するかを判定するエリア判定を行い、
    　前記無線リーダ装置との通信が失敗したと判定された場合に、前記エリア判定の判定結果に基づいて、前記エリアごとに定められた優先度に応じて、前記応答信号を再送する再送タイミングを制御し、
    　前記遠距離離脱エリアの優先度は最も高い第１優先度であり、前記近距離離脱エリアの優先度は前記第１優先度より低い第２優先度であり、前記近距離接近エリアの優先度は前記第２優先度より低い第３優先度であり、前記遠距離接近エリアの優先度は前記第３優先度より低い第４優先度であることを特徴とする再送制御方法。     A retransmission control method used in a wireless tag device,
    Receiving a response request signal transmitted from the wireless reader device;
    Measure the reception strength of the response request signal,
    A response signal transmitted as a response to the response request signal is received by the wireless reader device to determine whether communication with the wireless reader device is successful;
    Based on the reception strength of the previous response request signal and the reception strength of the current response request signal, when the reception strength is increased, it is determined as approaching, and when the reception strength is decreased, it is detached. Move determination to determine,
    Based on the reception strength of the response request signal this time, when the reception strength is equal to or greater than a predetermined threshold, it is determined as a short distance, and when the reception strength is less than the threshold, it is determined as a long distance Make a decision
    Based on the determination result of the movement determination and the perspective determination, an area determination is performed to determine which of the long-distance leaving area, the short-distance leaving area, the short-distance approaching area, and the long-distance approaching area,
    When it is determined that the communication with the wireless reader device has failed, the retransmission timing for retransmitting the response signal is controlled according to the priority determined for each area based on the determination result of the area determination And
    The priority of the long-distance leaving area is the highest first priority, the priority of the short-distance leaving area is the second priority lower than the first priority, and the priority of the short-distance approaching area is A retransmission control method, wherein the third priority is lower than the second priority, and the priority of the long-distance approach area is a fourth priority lower than the third priority.
  5. 　無線タグ装置と無線リーダ装置とを備えた無線通信システムであって、
    　前記無線タグ装置は、
    　前記無線リーダ装置から送信される応答要求信号を受信する受信部と、
    　前記応答要求信号の受信強度を測定する受信強度測定部と、
    　前記応答要求信号に対する応答として送信した応答信号が前記無線リーダ装置で受け付けられて前記無線リーダ装置との通信が成功したか否か判定する通信成否判定部と、
    　以前の応答要求信号の受信強度と今回の応答要求信号の受信強度とに基づいて、前記受信強度が増加している場合には接近と判定し、前記受信強度が減少している場合には離脱と判定する移動判定を行う移動判定部と、
    　前記今回の応答要求信号の受信強度に基づいて、前記受信強度が所定の閾値以上である場合には近距離と判定し、前記受信強度が前記閾値未満である場合には遠距離と判定する遠近判定を行う遠近判定部と、
    　前記移動判定と前記遠近判定の判定結果に基づいて、遠距離離脱エリア、近距離離脱エリア、近距離接近エリア、遠距離接近エリアのいずれのエリアに属するかを判定するエリア判定を行うエリア判定部と、
    　前記無線リーダ装置との通信が失敗したと判定された場合に、前記エリア判定の判定結果に基づいて、前記エリアごとに定められた優先度に応じて、前記応答信号を再送する再送タイミングを制御する再送タイミング制御部と、
    を備え、
    　前記遠距離離脱エリアの優先度は最も高い第１優先度であり、前記近距離離脱エリアの優先度は前記第１優先度より低い第２優先度であり、前記近距離接近エリアの優先度は前記第２優先度より低い第３優先度であり、前記遠距離接近エリアの優先度は前記第３優先度より低い第４優先度であることを特徴とする無線通信システム。     A wireless communication system comprising a wireless tag device and a wireless reader device,
    The wireless tag device is:
    A receiver for receiving a response request signal transmitted from the wireless reader device;
    A reception intensity measuring unit for measuring the reception intensity of the response request signal;
    A communication success / failure determination unit that determines whether a response signal transmitted as a response to the response request signal is received by the wireless reader device and communication with the wireless reader device is successful;
    Based on the reception strength of the previous response request signal and the reception strength of the current response request signal, when the reception strength is increased, it is determined as approaching, and when the reception strength is decreased, it is detached. A movement determination unit for performing movement determination to determine
    Based on the reception strength of the response request signal this time, when the reception strength is equal to or greater than a predetermined threshold, it is determined as a short distance, and when the reception strength is less than the threshold, it is determined as a long distance A perspective determination unit for performing the determination;
    An area determination unit that performs area determination to determine which of a long distance departure area, a short distance departure area, a short distance approach area, and a long distance approach area based on the determination result of the movement determination and the perspective determination When,
    When it is determined that the communication with the wireless reader device has failed, the retransmission timing for retransmitting the response signal is controlled according to the priority determined for each area based on the determination result of the area determination A retransmission timing control unit,
    With
    The priority of the long-distance leaving area is the highest first priority, the priority of the short-distance leaving area is the second priority lower than the first priority, and the priority of the short-distance approaching area is A wireless communication system, wherein the third priority is lower than the second priority, and the priority of the long-distance approach area is a fourth priority lower than the third priority.
  6. 　無線通信システムで用いられる再送制御方法であって、
    　無線リーダ装置から送信される応答要求信号を無線タグ装置で受信し、
    　前記無線タグ装置において、
    　前記応答要求信号の受信強度を測定し、
    　前記応答要求信号に対する応答として送信した応答信号が前記無線リーダ装置で受け付けられて前記無線リーダ装置との通信が成功したか否か判定し、
    　以前の応答要求信号の受信強度と今回の応答要求信号の受信強度とに基づいて、前記受信強度が増加している場合には接近と判定し、前記受信強度が減少している場合には離脱と判定する移動判定を行い、
    　前記今回の応答要求信号の受信強度に基づいて、前記受信強度が所定の閾値以上である場合には近距離と判定し、前記受信強度が前記閾値未満である場合には遠距離と判定する遠近判定を行い、
    　前記移動判定と前記遠近判定の判定結果に基づいて、遠距離離脱エリア、近距離離脱エリア、近距離接近エリア、遠距離接近エリアのいずれのエリアに属するかを判定するエリア判定を行い、
    　前記無線リーダ装置との通信が失敗したと判定された場合に、前記エリア判定の判定結果に基づいて、前記エリアごとに定められた優先度に応じて、前記応答信号を再送する再送タイミングを制御し、
    　前記遠距離離脱エリアの優先度は最も高い第１優先度であり、前記近距離離脱エリアの優先度は前記第１優先度より低い第２優先度であり、前記近距離接近エリアの優先度は前記第２優先度より低い第３優先度であり、前記遠距離接近エリアの優先度は前記第３優先度より低い第４優先度であることを特徴とする再送制御方法。     A retransmission control method used in a wireless communication system,
    The response request signal transmitted from the wireless reader device is received by the wireless tag device,
    In the wireless tag device,
    Measure the reception strength of the response request signal,
    A response signal transmitted as a response to the response request signal is received by the wireless reader device to determine whether communication with the wireless reader device is successful;
    Based on the reception strength of the previous response request signal and the reception strength of the current response request signal, when the reception strength is increased, it is determined as approaching, and when the reception strength is decreased, it is detached. Move determination to determine,
    Based on the reception strength of the response request signal this time, when the reception strength is equal to or greater than a predetermined threshold, it is determined as a short distance, and when the reception strength is less than the threshold, it is determined as a long distance Make a decision
    Based on the determination result of the movement determination and the perspective determination, an area determination is performed to determine which of the long-distance leaving area, the short-distance leaving area, the short-distance approaching area, and the long-distance approaching area,
    When it is determined that the communication with the wireless reader device has failed, the retransmission timing for retransmitting the response signal is controlled according to the priority determined for each area based on the determination result of the area determination And
    The priority of the long-distance leaving area is the highest first priority, the priority of the short-distance leaving area is the second priority lower than the first priority, and the priority of the short-distance approaching area is A retransmission control method, wherein the third priority is lower than the second priority, and the priority of the long-distance approach area is a fourth priority lower than the third priority.
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