JP6241817B2 - Wireless communication system - Google Patents

Description

  The present invention relates to a wireless communication system that performs wireless communication between a parent device and a child device via a relay device.

  Conventionally, in a wireless communication system, there is a problem that an error occurrence rate at the time of transmission / reception is high. When an error occurs, a retransmission request is automatically made from the reception side to the transmission side. For example, a control channel is used for an automatic retransmission request, and automatic retransmission control is performed in which the amount of data to be retransmitted is suppressed as much as possible when an error is detected (see, for example, Patent Document 1).

JP-A-9-284261

Further, in the radio communications system, in order to allow the transmission and reception without any problems even when the communication state between the master unit and the slave unit becomes worse, it is possible to install the repeater. In such a relay device, image data transmitted from the parent device is received and transferred to the monitor slave device by packet communication, for example.

  In the transfer processing at the repeater, for example, when transmitting and receiving packets in multiple slots in one frame by the TDMA (Time Division Multiple Access) method, the slot for transmitting packets at the repeater is changed to avoid jamming Then, the number of the packet to be transmitted may be mixed. For example, by restricting selection of a packet transmission slot on the transmission side (for example, a camera slave unit) and selection of a packet transmission slot on the relay unit, it is possible to prevent the packet order from being switched at the relay unit. However, there is a risk that processing may be delayed due to limitations.

  In addition, when the above-described restriction is not performed by the relay device, the monitor slave device receives a packet whose order has been changed, so that the monitor slave device transmits a negative response (NACK) requesting retransmission of the missing number of packets. Send. In this case, there is a problem that the data processing becomes complicated and a delay occurs because the retransmission processing is performed despite the transmission in the normal order from the parent device.

  The present invention has been devised to solve such problems of the prior art, and its main purpose is to perform data processing smoothly and promptly when data is transmitted / received via a repeater. It is to provide a wireless communication system.

The wireless communication system of the present invention is a wireless communication system that wirelessly performs transmission / reception between a parent device and a child device, and includes a relay device that relays transmission / reception between the parent device and the child device, The packet is transmitted in numerical order, and the slave sets a reception waiting number setting unit that sets the number of the packet to be received next as a reception waiting number when the packet is received in numerical order, and at a predetermined timing. A retransmission control unit that determines an update status of the reception waiting number and transmits a response signal requesting retransmission of the packet to the relay based on the determination result, and the retransmission control unit includes the reception waiting number When it is determined that the number has not been updated, a negative response is transmitted, and the base unit has a storage unit that sequentially stores the packets to be transmitted, and when the storage unit is full, an old packet is transmitted. Discard and new A structure that operates to store the packets to be sent to.

According to the present invention, packets transmitted in the numerical order from the parent device and received by the relay device are transmitted in a reversed order in order to avoid the influence of jamming radio waves, so that the number of the packet received by the child device is changed. In this case, the packet with the reception waiting number is not received. Therefore, even if the reception waiting number is not updated accordingly, the retransmission is not requested immediately. When the reception waiting number is not updated, the retransmission is not requested. Since the response is transmitted, it is not necessary to frequently perform processing by retransmission, and the occurrence of delay can be suppressed. If packets are sent in numerical order from the base unit, the numbers are simply switched in the processing at the repeater, so when sending and receiving packets in multiple slots in one frame, the changed number in that frame In this case, since the reception waiting number is updated by the transmission timing of the response signal in the next frame, transmission / reception can be continued as it is. In addition, when the slave unit receives a packet stored error in the storage unit, it can be retransmitted easily, and resources such as memory necessary for the operation can be reduced.

The figure which shows the example of a whole structure of the radio | wireless communications system to which this invention was applied. Block diagram schematically showing the circuit configuration of the main unit Block diagram schematically showing the circuit configuration of the door phone slave unit Block diagram schematically showing the circuit configuration of the camera slave unit Block diagram schematically showing the circuit configuration of the monitor slave unit Block diagram schematically showing the circuit configuration of the repeater The figure which shows the structural example of the frame slot in the time division multiplex communication (TDM etc.) system to which this invention was applied. (A) is a field structure of a control channel, (b) is a figure which shows the field structure of a communication channel. The figure which shows the operation example during communication performed via the relay machine between a main | base station and a monitor cordless handset The figure which shows the flow of the packet reception control in the monitor subunit | mobile_unit by this invention The figure which shows the specific example of the operation | movement of the transmission / reception control between the monitor subunit | mobile_unit and a main | base station via a relay machine FIG. 9 is a diagram corresponding to FIG. 9 when a part of data reception by the monitor slave unit is changed. The figure which shows the flow of transmission control of the retransmission control signal in the monitor subunit | mobile_unit by this invention Diagram corresponding to FIG. 11 when a data reception error occurs

A first invention made to solve the above-described problems is a wireless communication system that wirelessly performs transmission / reception between a parent device and a child device, the relay device relaying transmission / reception between the parent device and the child device. The master unit transmits packets in numerical order, and the slave unit sets the number of the packet to be received next as a reception standby number when the packet is received in numerical order. A retransmission control unit that determines an update status of the reception waiting number at a predetermined timing and transmits a response signal requesting retransmission of the packet to the relay based on the determination result, When it is determined that the reception waiting number has not been updated, the control unit transmits a negative response, and the master unit has a storage unit that sequentially stores the packets to be transmitted, and the storage unit is full. If it becomes old Discard the packet and configured to operate so as to store the packet to be newly transmitted.

According to this, packets sent by the base unit in the order of numbers and received by the repeater are sent out of order in order to avoid the influence of jamming radio waves, so that the numbers of the packets received by the handset have changed. In this case, since the packet of the reception waiting number is not received, even if the reception waiting number is not updated accordingly, a retransmission is not requested immediately, and if it is not updated, a negative response requesting retransmission is transmitted. Therefore, it is not necessary to frequently perform processing by retransmission, and the occurrence of delay can be suppressed. If packets are sent in numerical order from the slave unit, the numbers are simply switched in the processing at the relay unit. Therefore, when packets are sent and received in multiple slots in one frame, the changed number in that frame. In this case, since the reception waiting number is updated by the transmission timing of the response signal in the next frame, transmission / reception can be continued as it is. In addition, when the slave unit receives a packet stored error in the storage unit, it can be retransmitted easily, and resources such as memory necessary for the operation can be reduced.

  Further, in a second aspect based on the first aspect, the slave unit has a storage unit for storing the packet, and the retransmission control unit determines that the reception waiting number has not been updated, And when the said packet is preserve | saved at the said memory | storage part, it is set as the structure which transmits a negative response.

According to this, if the reception waiting number has not been updated and the packet is not stored in the storage unit, the negative response is not sent, so the data sent by the master unit is temporarily lost, and the slave unit side in even state waiting number is not updated is generated, if the packet loss by the receiving error has not occurred, because the negative response is not transmitted, it can suppress the generation of unnecessary retransmissions.

In a third aspect based on the first aspect, the slave unit starts receiving a packet and sets the number of the first received packet as a reception waiting number.

  According to this, it is not necessary to receive the first packet from which the parent device has started transmission, and it is possible to construct data even when receiving from the middle.

A fourth aspect of the present invention is transmitted in the first aspect of the present invention, the base unit transmits a frame number, before Symbol slave unit, a negative response in the own transmission permission frame which is determined based on the frame number The configuration is as follows.

  According to this, even if there are a plurality of slave units in the system, it is possible to suppress the occurrence of a communication failure due to a collision of transmission of negative responses from those slave units.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an example of the overall configuration of a wireless communication system to which the present invention is applied. In the figure, a master unit 1 is disposed at a predetermined location in the house, a doorphone slave unit 2 is disposed at or near the door DR of the house, and a camera slave unit 3 for monitoring the outside of the house is provided on the outer wall. In the illustrated example, two portable monitor slave units 4 are provided in the illustrated example. The portable monitor slave units 4 are mainly used in a house. A repeater 5 is provided at an appropriate position so that transmission / reception between the parent device 1 and each of the child devices 3 and 4 can be performed satisfactorily.

  FIG. 2 is a block diagram schematically showing the circuit configuration of the base unit 1. As shown in the figure, the base unit 1 performs signal transmission / reception with the door phone slave unit 2 in the illustrated example by a wire, and is connected to the interface unit 1a and performs main control of the base unit 1. A control unit 1b constituting a retransmission control unit and a reception waiting number setting unit, an image processing unit 1c connected to the control unit 1b and the interface unit 1a, and an audio processing unit 1d connected to the control unit 1b and the interface unit 1a The operation unit 1e is connected to the control unit 1b and transmits an operation of a button switch or the like provided in the base unit 1 to the control unit 1b. A microphone 1f and a speaker 1g are connected to the audio processing unit 1d, and a display unit 1h having an LCD, for example, is connected to the image processing unit 1c. A frame processing unit 1i connected to the audio processing unit 1d and a radio unit 1j connected to the frame processing unit 1i are connected to the control unit 1b. An antenna 1k for wireless communication is connected to the wireless unit 1j. In addition, a number storage unit 1m and a data storage unit 1n are connected to the control unit 1b. Packets transmitted from the camera slave unit 3 in numerical order are stored in the data storage unit 1n, and a storage sequence number SNm corresponding to the stored packet number is stored in the number storage unit 1m. The control unit 1b is connected to a buffer unit 1o that temporarily stores a predetermined amount of image data from the doorphone slave unit 2 and the camera slave unit 3 as transmission packet data.

  FIG. 3 is a block diagram schematically showing a circuit configuration of the door phone slave unit 2. As shown in the figure, the door phone slave unit 2 performs the main control of the door phone slave unit 2 connected to the interface unit 2a and the interface unit 2a for performing signal transmission / reception with the master unit 1 by wire in the illustrated example. The control unit 2b, the image processing unit 2c connected to the control unit 2b and the interface unit 2a, the audio processing unit 2d connected to the control unit 2b and the interface unit 2a, and the doorphone slave unit 2 connected to the control unit 2b And an operation unit 2e for transmitting an operation of a button switch or the like provided to the control unit 2b. A microphone 2f and a speaker 2g are connected to the audio processing unit 2d, and a camera unit 2h for photographing outside the vicinity of the door DR is connected to the image processing unit 2c.

  FIG. 4 is a block diagram schematically showing a circuit configuration of the camera slave unit 3. As shown in the figure, the camera slave unit 3 includes a control unit 3b that performs main control, an image processing unit 3c connected to the control unit 3b, an audio processing unit 3d connected to the control unit 3b, and a control unit. And an operation unit 3e that is connected to 3b and transmits an operation of a button switch or the like provided in the camera slave unit 3 to the control unit 3b. A microphone 3f and a speaker 3g are connected to the audio processing unit 3d, and a camera unit 3h for photographing the outside of the house, for example, is connected to the image processing unit 3c. A frame processing unit 3i connected to the audio processing unit 3d and a radio unit 3j connected to the frame processing unit 3i are connected to the control unit 3b. An antenna 3k for wireless communication is connected to the wireless unit 3j. Further, the control unit 3b is connected to a detection unit 3l having a human sensor such as an infrared sensor, and a buffer unit 3n for temporarily storing a predetermined amount of image data from the image processing unit 3c as transmission packet data. It is connected.

  FIG. 5 is a block diagram schematically showing a circuit configuration of the monitor slave unit 4. As shown in the figure, the monitor slave unit 4 includes a control unit 4b that performs main control, an image processing unit 4c that is connected to the control unit 4b, an audio processing unit 4d that is connected to the control unit 3b, and a control unit. 4b and an operation unit 4e for transmitting an operation of a button switch or the like provided on the monitor slave unit 4 to the control unit 4b. A microphone 4f and a speaker 4g are connected to the sound processing unit 4d, and a display unit 4h having an LCD, for example, is connected to the image processing unit 4c. The control unit 4b is connected to a frame processing unit 4i connected to the audio processing unit 4d and a radio unit 4j connected to the frame processing unit 4i. An antenna 4k for wireless communication is connected to the wireless unit 4j. In addition, a number storage unit 4m and a data storage unit 4n are connected to the control unit 4b. Packets transmitted from the parent device 1 in the numerical order are stored in the data storage unit 4n, and a storage sequence number SNm corresponding to the stored packet number is stored in the number storage unit 4m.

  FIG. 6 is a block diagram schematically illustrating a circuit configuration example of the repeater 5. As shown in the figure, the relay unit 5 includes a control unit 5b that performs main control, an image processing unit 5c that is connected to the control unit 5b, and a registration operation that is connected to the control unit 5b and is registered in the base unit 1. And an operation unit 5e for transmitting operations such as button switches to the control unit 5b. Connected to the image processing unit 5c is a display unit 5h for displaying the reception state of radio waves (synchronization with the base unit 1, etc.) by, for example, an LCD. The control unit 5b is connected to a frame processing unit 5i and a radio unit 5j connected to the frame processing unit 5i. An antenna 5k for wireless communication is connected to the wireless unit 5j. A buffer unit 5n is connected to the control unit 5b.

  When the relay device 5 relays communication between the parent device 1 and the monitor child device 4, the received packet from the parent device 1 is temporarily stored in the buffer unit 5n. The packet stored in the buffer unit 5n is read in the processing of the next frame and transmitted to the monitor slave unit 4 using a plurality of slots. Similarly, the received data from the monitor slave unit 4 is stored in the buffer unit 5n, read in the processing of the next frame, and transmitted to the master unit 1.

  Next, the wireless communication control procedure in the wireless communication system configured as described above will be described below.

  FIG. 7 is a diagram showing a configuration example of frames and slots in a time division multiplex communication (TDM or the like) system to which the present invention is applied. This time division multiplex communication is used for communication with each of the slave units 3 and 4 that wirelessly communicate with the master unit 1. In the figure, one frame is a basic unit communicated in units of 10 msec, for example, and conforms to the domestic DECT (ETSI trademark) standard. In one frame, 24 slots (S1 to S24) are provided in the illustrated example. In the illustrated example, one communication channel is formed by two slots and combined at an interval of 5 msec (12 slots). For example, one channel is formed by the slot S1 and the slot S13.

  FIG. 8 is a diagram showing a field configuration of a radio signal used in the time division multiplex communication in the present embodiment. This corresponds to the contents of the slot, and FIG. 8A shows the field configuration of the control channel, the state other than the incoming call from the doorphone slave unit 2 or the camera slave unit 3 (non-incoming state), and the doorphone slave unit. 2 and a field configuration of a slot for a retransmission control signal between the master unit 2 and the monitor slave unit 4 in a state in which an incoming call is received from the camera slave unit 3 (incoming state). FIG. 8B shows the field configuration of the communication channel. In the incoming state from the doorphone slave unit 2 or the camera slave unit 3, the slot used for the control channel and the slot used for the audio signal or image signal are shown. It is a field configuration.

  The field configuration shown in FIG. 8A includes a synchronization signal field F1, a control data field F2, and a CRC1 field F3. The synchronization signal field F1 is a field composed of a data string for achieving bit synchronization and a data string for achieving slot synchronization. The control data field F2 is a field for control data such as a frame for time division multiplex communication, a signal for slot synchronization, and a signal transmitted from the master unit 1 for calling the slave units 2 to 4. is there. The CRC1 field F3 is a field for error detection data in the control data field, and is a field into which error detection data corresponding to the data string of the control data field is inserted. When an information data field is arranged subsequent to the CRC1 field F3, the information data field is a field for audio data / image data.

  The field configuration shown in FIG. 8B is composed of the same sync signal field F1, control data field F2, CRC1 field F3, information data field F4, and CRC2 field F5 as described above. FIG. 8 (b) is in communication as described above, and its control data field F2 is a field for control data such as communication channel and service activation / disconnection, and data communication retransmission control data. It is. The information data field F4 is a field for audio data, image data, and retransmission control data.

  Next, an example of an operation for displaying an image photographed by the camera slave unit 3 in the wireless communication system configured as described above on the master unit 1 and the monitor slave unit 4 will be described. In this wireless communication system, imaging by the camera unit 3h is started by the sensor reaction of the detection unit 3l provided in the camera slave unit 3, the sensor response is notified by wireless communication, and at the same time, the captured image is captured by the master unit 1 and the monitor unit. A function of transmitting to the machine 4 (hereinafter referred to as camera incoming call). When the camera incoming call is notified from the camera slave unit 3, the master unit 1 sounds a notification sound for notifying the camera incoming from the speaker 1g, activates a wireless line for data communication with the camera slave unit 3, and receives an image. Start. The base unit 1 stores the packet of the image data sent from the camera slave unit 3 in the data storage unit 1n, and stores the received packet number in the number storage unit 1m, and sends an acknowledgment ACK and a negative response NACK to the camera. The image data is transmitted to the child device 3 to reconstruct the image data, and the received image data is displayed on the LCD of the display unit 1h. The master unit 1 notifies the monitor slave unit 4 of the incoming camera by a control signal, and notifies the camera image transmission slot and the retransmission request reception slot. The master unit 1 divides the reconstructed image data into packets for communication with the slave unit, sequentially stores them in the buffer unit 1o, and sequentially transmits them in the camera image transmission slot notified by the control signal. When the buffer unit 1o becomes full, the old packets are discarded in sequence, and the stored packets are updated. When a negative response NACK is received from the monitor slave unit 4, the buffer unit 1 o is searched, and if a packet with a sequence number notified with the negative response NACK remains, a packet with the sequence number notified with the negative response NACK is detected. Operates to resend.

  Next, the operation of the monitor slave unit 4 when the camera arrives will be described. When an incoming camera is notified through the control channel, reception of the notified slot for transmitting the camera image is started, a packet of image data sent from the base unit 1 is stored in the data storage unit 4n, and a number storage unit 4m The negative packet NACK is transmitted to the main unit 1 as necessary while storing the received packet number, and the image data is reconstructed, and the received image data is displayed on the LCD of the display unit 4h. Note that all the monitor slave units 4 in the system operate in the same manner, receive image data transmitted from the master unit 1 at the same time, and the camera slave unit 3 displays the LCD of the display unit 4h of all the monitor slave units 4. The captured image is displayed. Each of the monitor slave units 4 transmits a negative acknowledgment NACK to the master unit 1 when the occurrence of a packet loss is detected by a method described later. At this time, the base unit transmits a frame number incremented for each frame by a control signal, and each slave unit determines the transmission timing (frame number) of a negative acknowledgment NACK by a predetermined method based on the frame number. By doing so, it is also possible to control so that the transmission timing of the negative acknowledgment NACK does not collide. For example, if there are two monitor slave units 4 in the system, one monitor slave unit transmits a negative acknowledgment NACK with an even frame number frame, and the other monitor slave unit has an odd frame number frame. By transmitting a negative response NACK at, it is possible to control so that the negative response NACKs from the two monitor slave units 4 do not collide. Also, when the monitor slave unit 4 is notified of an incoming call and starts receiving a packet of image data, the monitor slave unit 4 may start packet retransmission control with the frame number of the first received packet as an initial value. For example, if the monitor slave unit 4 that is outside the reception range of the master unit 1 moves into the reception range of the master unit 1 while the incoming call is received, the monitor slave unit 4 receives the packet from the middle. In this case, by setting the sequence number of the first received packet as an initial value of a reception waiting sequence number SNw described later, it becomes possible to receive an image from the middle.

  Next, the operation of the repeater 5 when the camera arrives when the repeater 5 relays wireless communication between the master unit 1 and the monitor slave unit 4 will be described. When the camera incoming call is notified through the control channel, the camera image between the monitor slave unit 4 and the relay unit 5 and the communication slot for the retransmission request are determined, and the camera incoming call is notified to the monitor slave unit 4 by the control signal. And the retransmission request reception slot. The relay unit 5 operates to temporarily store the camera image data received from the base unit 1 in the buffer unit 5n and transmit it to the monitor slave unit 4 in the next frame. Similarly, the relay unit 5 receives the data from the monitor slave unit 4 The retransmission request is temporarily stored in the buffer unit 5n, and is transmitted to the base unit 1 in the next frame.

  FIG. 9 is a diagram illustrating an operation example during an incoming call from the door phone slave unit 2 or the camera slave unit 3 performed via the relay unit 5 between the master unit 1 and the monitor slave unit 4. In the figure, a packet transmitted in sequence number SN as a packet number from the base unit 1 with the frame number N is transmitted (transferred) to the monitor slave unit 4 with the next frame number N + 1 via the relay unit 5. The state is shown. As shown in FIG. 9, image data is transmitted from the parent device 1 using four slots during an incoming call. The monitor slave unit transmits a retransmission request signal in one slot. When the main unit enters the incoming state, it notifies that the incoming call is being received by a control signal, and notifies the slot for transmitting the image data and the slot for receiving the retransmission request. When the relay device 5 is notified by the control signal from the master device that the incoming call state has been entered, the relay device 5 switches the operation to relay the image data and the retransmission request. That is, the relay unit 5 notifies the monitor slave unit 4 that has received the relay unit 5 that the incoming call is being received by a control signal, and receives (relays) a slot for transmitting (relaying) image data and a retransmission request. ) Notify the slot.

  In the frame number N of the relay unit 5 in the illustrated example, the slots S1, S10, S11, S12, S23, and S24 are used for transmission / reception with the monitor slave unit 4, and the slots S2, S4, S5, S6, S17, and S18 are used. The control signal transmitted from the parent device 1 is received in the slot S2, and the control signal is transmitted to the monitor slave device 4 in the slot S1. The retransmission control signal transmitted from the monitor slave unit 4 is received in the slot S10 and transmitted to the master unit 1 in the slot S4. Further, the packet already transmitted from the parent device 1 and stored in the buffer unit 5n is transmitted to the monitor slave device 4 in each of the slots S11, S12, S23, and S24. In the figure, each packet transmitted to the monitor slave unit 4 is represented using each image data DT (0), DT (1), DT (2), DT (3) included therein (hereinafter, referred to as “packet”). The same shall apply). Also, the next image data (each packet) DT (4), DT (5), DT (6), DT (7) transmitted from the base unit 1 is received in each of the slots S5, S6, S17, S18. And transmitted to the monitor slave unit 4. In FIG. 9, the monitor slave unit 4 transmits a retransmission control signal in the slot S10, and the relay unit 5 transmits the retransmission control signal received in the slot S4 of the next frame to the master unit 1. However, as described later, when there is no reception error in the monitor slave unit 4 and it is not necessary to transmit a negative acknowledgment NACK requesting retransmission of the data packet, the monitor slave unit 4 transmits a retransmission control signal. In the next frame slot S4, the relay station does not transmit anything.

  In a normal state where there is no influence of the jamming radio wave on each use slot, transmission / reception is continued in a state indicated by a frame number N + 1 using each slot having the same configuration after the frame number N shown in FIG. In this way, wireless communication is performed between the master unit 1 and the monitor slave unit 4 via the relay unit 5, whereby the relay unit 5 temporarily stores the received data in the buffer unit 5n, and the next Sent in frames.

  Since the image data to be processed in one frame has a large capacity, it is transmitted and received using a plurality of slots (four slots in the illustrated example) as described above. The receiving side (monitor slave unit 4) processes each image data in the order of the sequence number SN which is the packet number. This embodiment is an example in which an image of one screen is reproduced with four image data. The repeater 5 may change the slot targeted for countermeasures against jamming to another slot, and the sequence number SN transmitted from the repeater 5 to the monitor slave unit 4 becomes discontinuous. A control procedure according to the present invention in the monitor slave unit 4 in that case will be described below.

  FIG. 10 is a control flow of reception processing in the monitor slave unit 4 according to the present invention, and is a diagram showing a flowchart at the time of packet (image data DT) reception. The control is mainly performed by the control unit 4b and may be configured by a program. In the illustrated example, this reception process is executed when a packet is normally received at the end (immediately) of each slot S11, S12, S23, and S24 of each frame.

  FIG. 11 is a diagram illustrating a specific example of the operation of transmission / reception control between the master unit 1 and the monitor slave unit 4 via the relay unit 5. In FIG. 11, the vertical axis is the time axis from the top to the bottom, and the state from the first frame number 1 when the image data DT is transmitted from the parent device 1 is shown. Further, the processing of the reception signal (right arrow in the figure) from the repeater in FIG. 11 is performed according to the flowchart in FIG. 10, and the processing of the transmission signal from the monitor slave unit 4 to the repeater (left arrow in the figure) will be described later. This is performed according to the flowchart of FIG.

  In step ST1 of FIG. 10 where the reception process is performed, it is determined whether or not the sequence number SNr of the received packet is the same as the reception waiting sequence number SNw which is the number of the packet to be received next. This determination is performed by the control unit 4b constituting the retransmission control unit by comparing the reception waiting sequence number SNw stored in the number storage unit 4m with the sequence number SNr of the received packet.

  As indicated by frame number 1 in FIG. 11, four image data DT (0) to DT (3) constituting one screen are transmitted from the parent device 1 in this order and received by the relay device 5. Here, the numbers in parentheses indicate the packet sequence numbers SN as n = 0, 1, 2,... For example, the image data DT (0) corresponds to a packet whose sequence number SN is “0”.

  In frame number 1, the relay device 5 has no received image data DT, and transmits no signal (NULL) to the monitor slave device 4 using the same slot. Since the monitor slave unit 4 has no image data DT, the reception waiting sequence number SNw is “0” corresponding to the image data DT (0) to be received first.

  In the example of FIG. 11, as indicated by frame numbers 1 and 2, the image data DT (2) is transmitted after the image data DT (0) · DT (1) in the processing in the relay 5. Instead, the image data DT (3) is transmitted first, and then the image data DT (2) is transmitted.

  The reason why the slot correspondence in the repeater 5 is changed in this way is that it is determined that the use frequency of the received slot is affected by the interference wave, and channel switching is performed to select another slot that is not affected by the interference. It depends. A specific example will be described with reference to FIG. 12 corresponding to FIG.

  In the frame number N + 1 in FIG. 12, in order to avoid the influence of jamming radio waves, each slot for transmitting the image data DT (5) and DT (7) from the repeater 5 to the monitor slave unit 4 starts from S12 in FIG. It is changed to S9, and similarly, it is changed from S24 of FIG. 9 to S21. As a result, for the image data DT (4) · DT (5) received from the base unit 1 received at the frame number N, a slot to be transmitted to the monitor slave unit 4 at the next frame number N + 1 is set to the image data DT (4 ) Uses the slot S11, but the image data DT (5) uses the slot S9. Similarly, in the next frame number N + 1, the image data DT (6) is received in the slot S23 and the image data DT (7) is in the slot S21. Will be used. Note that the slot (channel) change in the repeater 5 is appropriately performed when there is a possibility that the slot that has been used interferes with jamming radio waves, and the slot to be changed may be arbitrary. As shown in the example, the packet transfer order may be changed. In FIG. 12, in the slot S10, the monitor slave unit 4 transmits a retransmission control signal, and the relay unit 5 transmits the retransmission control signal received in the slot S4 of the next frame to the master unit 1. However, as described later, when there is no reception error in the monitor slave unit 4 and it is not necessary to transmit a negative acknowledgment NACK requesting retransmission of the data packet, the monitor slave unit 4 transmits a retransmission control signal. Without repeating, the relay unit 5 does not transmit anything in the slot S4 of the next frame.

  In step ST2, which proceeds when it is determined in step ST1 that they match, the image data DT of the received packet is output to the image processing unit 4c. In the image processing unit 4c, for example, the image data DT (n) to DT (n + 3) are received until reception of a plurality of pieces of image data DT (n) to DT (n + 3) necessary for reproducing an image for one screen is completed. When the reception of the plurality of image data DT (n) to DT (n + 3) necessary for reproducing the image for one screen is completed, the image data (n) to DT (n + 3) are displayed on the display unit 1h. Output. In the display unit 1h, the image data (n) to DT (n + 3) are combined and displayed on the monitor screen.

  In the next step ST3, the reception waiting sequence number SNw is updated to the number of the packet to be received next (n ← n + 1), and the process proceeds to step ST4. In step ST4, it is determined whether or not the reception waiting sequence number SNw updated in step ST3 is included in the stored sequence number SNm stored in the number storage unit 4m. In the initial state, the reception waiting sequence number SNw is “0”.

  If it is determined in step ST1 that the sequence number SNr received in the image data DT does not match the reception waiting sequence number SNw, the process proceeds to step ST5.

  In step ST5, it is determined whether or not the received sequence number SNr is new. If the received sequence number SNr is new, the process proceeds to step ST6.

  In step ST6, the received packet of the received sequence number SNr is stored in the data storage unit 4n, and the received sequence number SNr is stored in the stored sequence number SNm.

  If it is determined in step ST5 that it is not new, the process proceeds to step ST7. In step ST7, since the packet with the sequence number SNr received in that case is already received, the packet with the sequence number SNr is discarded.

  If it is determined in step ST4 that the reception waiting sequence number SNw matches the number stored in the stored sequence number SNm, the process proceeds to step ST8. In this case, in the example of FIG. In step ST8, the packet having the sequence number matching the reception waiting sequence number SNw is taken out from the data storage unit 4n, and the image data DT (n) in the packet is output to the image processing unit 4c. Then, the packet number output from the storage sequence number SNm is deleted.

  In the next step ST9, the sequence number SNw waiting for reception is updated (n ← n + 1) as in step ST3, and the process returns to step ST4. In this case, steps ST8 and ST9 are repeated until it is determined in step ST4 that there is no stored data corresponding to the reception waiting sequence number SNw in the data storage unit 4n.

  In the flow of packet reception processing of FIG. 10, after performing the processing of steps ST6 and ST7 or in step ST4 described above, the reception waiting sequence number SNw and the stored sequence number SNm stored in the number storage unit 4m If it is determined that they do not match, the process ends.

  FIG. 13 is a diagram illustrating a flowchart at the time of retransmission control signal transmission. The control in this case is also performed mainly by the control unit 4b and may be configured by a program. This retransmission control signal (response signal) transmission process (flow in FIG. 13) is executed at the beginning (immediately before) of slot S10 of each frame.

  In the transmission process flow of FIG. 13, in step ST11, the reception waiting sequence number SNw (sequence number SNw stored in step ST15 described later) at the timing of transmitting the previous retransmission control signal and the current retransmission control signal are transmitted. It is determined whether or not the reception waiting sequence number SNw is different (updated). If it is determined in step ST11 that it has not been updated, the process proceeds to step ST12.

  In step ST12, it is determined whether or not the image data DT is stored in the data storage unit 4n based on whether or not the storage sequence number SNm is stored in the number storage unit 4m. If it is determined that the image data DT has not yet been received at frame number 1 in FIG. 11 and the image data DT has not been stored in the data storage unit 4n, the process proceeds to step ST15.

  If it is determined in step ST12 that the image data DT is stored in the data storage unit 4n, the process proceeds to step ST14. In step ST14, since the image data DT that has not yet been processed is stored in the data storage unit 4n, a negative response NACK (n that requests retransmission of the packet corresponding to the number “n” of the reception waiting sequence number SNw is received. ). After step ST14, the process proceeds to step ST15.

  The retransmission control unit that determines transmission of the negative response NACK and performs transmission control is provided in the control unit 4b and may be configured by a program, for example.

  In step ST15, the reception waiting sequence number SNw (= n) at the timing for transmitting the retransmission control signal is stored. In this way, the flow of retransmission control in FIG. 13 is executed.

  The control point based on the flow of FIG. 10 and FIG. 13 configured as described above will be described below with reference to the operation examples of FIG. 11 and FIG.

  The operation example in frame number 1 in FIG. 11 is as described above, the reception waiting sequence number SNw is “0”, and nothing is transmitted in the transmission process of the retransmission control signal.

  When moving to the next frame number 2, the image data DT (0) is received by packet processing using the first slot. In this case, the flow of FIG. 10 is executed, and since the received sequence number SNr (= 0) and the reception waiting sequence number SNw (= 0) are the same, the process proceeds from step ST1 to step ST2. In step ST2, the received image data DT (0) is output to the image processing unit 1c, and in next step ST3, the reception waiting sequence number SNw is updated to “1” which is the number of the next packet to be received.

  At this time, since the image data DT is not stored in the data storage unit 4n, it is determined in step ST4 that the reception waiting sequence number SNw and the storage sequence number SNm do not match, and the next packet reception process is executed. . In the illustrated example, as indicated by frame number 2, the image data DT (2) is not received and the image data DT (3) is received. In this case, since the reception waiting sequence number SNw is “2”, the received sequence number SNr (= 3) does not match, and the process proceeds from step ST1 to step ST5. Since the received sequence number SNr (= 3) is new, the process proceeds to step ST6. In step ST6, the image data DT (3) is stored in the data storage unit 4n, and the stored sequence number SNm is set to “3”. The number is stored in the number storage unit 4m.

  Next, the retransmission control signal transmission flow of FIG. 13 is executed. Since the reception waiting sequence number SNw is updated from “0” to “2” at the previous retransmission control signal transmission timing, the process proceeds from step ST11 to step ST15. In the next step ST15, “2” of the reception waiting sequence number SNw is stored.

  Next, as shown in frame number 2, image data DT (2) is received, and the flow of FIG. 10 is executed. In step ST1 in this case, since the received sequence number SNr and the reception waiting sequence number SNw match with “2”, the process proceeds to step ST2. In step ST2, the image data DT (2) is transmitted to the image processing unit 4c, and in step ST3, the reception waiting sequence number SNw is updated to “3”. In step ST4, since it is determined that the reception waiting sequence number SNw (= 3) matches the storage sequence number SNm (= 3), the process proceeds to step ST8.

  In step ST8, the image data DT stored in the data storage unit 4n corresponding to the storage sequence number SNm (= 3) is output to the image processing unit 4c. In the example of FIG. 11, image data DT (3) is output as indicated by frame number 2. In next step ST9, the reception waiting sequence number SNw is updated to “4”, and the process returns to step ST4. In step ST4, since there is no storage sequence number SNm that matches the reception waiting sequence number SNw (= 4) at this time, the flow of FIG.

  In this way, when the slot is changed as a countermeasure against jamming radio waves in the repeater 5, a plurality of receiving NACKs requesting retransmission immediately without transmitting like the conventional retransmission control signal transmission control are transmitted. Image data DT can be received sequentially and processing can continue. Therefore, when a packet can be normally received, it is possible to perform a process that does not require retransmission, thereby preventing a delay in the process.

  Frame numbers 3 and 4 in FIG. 11 show an example in which transmission / reception is performed in the repeater 5 with the slot changed in frame number 2 being changed. Each image data DT (4) to (7) transmitted from the master unit 1 with the frame number 2 is received with the frame number 3 of the monitor slave unit 4, and each image data DT transmitted with the frame number 3 from the master unit 1 is received. (8) to (11) are received by the monitor slave unit 4 at the frame number 4. The process is the same as that described above except that the sequence number SN is updated.

  Next, an operation example when a reception error occurs in a part of the plurality of image data DT will be described below with reference to FIG. 14 corresponding to FIG. In addition, in the transmission / reception of each data indicated by the frame numbers 5 to 8 in FIG. 14, the description of the same part as in FIG. 11 is omitted.

  In frame number 5, each image data DT (12) to (15) transmitted from base unit 1 in frame number 4 of FIG. 11 is transmitted (transferred) to monitor slave unit 4 via relay unit 5. An example in which a reception error occurs in the image data DT (13) therein and the monitor slave unit 4 cannot receive the image data DT (13) is shown. Note that the image data DT (15) and the image data DT (14) are moved back and forth due to the slot change as a countermeasure against the jamming radio wave shown in FIG.

  In this case, the received sequence number SNr is “15” by the reception of the image data DT (15), whereas the reception waiting sequence number SNw is “13”. The process proceeds from step ST1 to step ST5. Since the received sequence number SNr (= 15) is new, the process proceeds from step ST5 to step ST6, where the image data DT (15) is stored in the data storage unit 4n, and the storage sequence number SNm is set to “15”. The number is stored in the number storage unit 4m.

  Next, the flow of retransmission control signal transmission processing in FIG. 13 is executed. In step ST11, the reception waiting sequence number SNw at the time of the previous retransmission control signal transmission is “10” as indicated by frame number 4, whereas reception is performed by receiving image data (12) at frame number 5. Since the waiting sequence number SNw has been updated to “13”, the process proceeds to step ST15. In step ST15, the reception waiting sequence number SNw (= 13) at the retransmission control signal transmission timing is stored.

  In the last process in frame number 5, image data DT (14) is received. In this case, since the received sequence number SNr is “14” while the reception waiting sequence number SNw is “13”, the process proceeds from step ST1 to step ST5. Save DT (14).

  In frame number 6, the image data DT (16), (17), and (19) are received in this order. Also in the flow of FIG. 10 in which these reception processes are performed, the process proceeds from step ST1 to ST5 and ST6, respectively, and is stored in the data storage unit 4n in the same manner as the image data DT (15) and each sequence number SN ( = 16, 17, 19), the storage sequence number SNm is stored in the number storage unit 4m as “16”, “17”, “19”.

  In addition, since the reception waiting sequence number SNw (= 13) at the time of the previous retransmission control signal transmission is not updated at the storage timing of each storage sequence number SNm, in the processing of the flow of FIG. The process proceeds from step ST11 to step ST12. In step ST12, it is determined that there is a stored sequence number SNm in the number storage unit 4m, and the process proceeds to step ST14. In step ST14, a negative acknowledgment NACK (13) is transmitted. In the next step ST15, the reception waiting sequence number SNw (= 13) at the time of transmission is stored.

  In frame number 6, image data DT (18) is received in the packet processing after the transmission of the negative acknowledgment NACK (13). Even in this case, the reception waiting sequence number SNw remains “13”.

  At the next frame number 7, the master unit 1 receives the negative acknowledgment NACK (13) transmitted from the monitor slave unit 4 at the frame number 6, and accordingly, from the image data stored in the buffer unit 1o. The image data DT (13) is transmitted using the slot next to the reception slot of the negative acknowledgment NACK (13). The image data DT (24), DT (25), and DT (26) are transmitted using the three slots before the negative response NACK (13).

  In the frame number 7, the monitor slave unit 4 has not received the image data DT (13) yet, so that the image data DT (20), (21), (23) is stored as in the process in the frame number 6. The data is received in this order and stored in the data storage unit 4n in the same manner as step ST6 in frame number 6, and each stored sequence number SNm (= 20, 21, 23) corresponding to each sequence number SN is stored in the number storage unit 4m. save.

  In the next frame number 8, the monitor slave unit 4 first receives the image data DT (24) / DT (25) in this order, and then receives the image data DT (13). The reception process in this case will be described below with reference to the flow of FIG.

  Since the received sequence number SNr is “13” and the reception waiting sequence number SNw is “13”, the process proceeds from step ST1 to step ST2, and the image data DT (13) is output to the image processing unit 4c. In the next step ST3, the reception waiting sequence number SNw is updated to “14”, and the process proceeds to step ST4. At this time, by the storage process, the storage sequence numbers SNm (= 14 to 25) are stored in the number storage unit 4m, and the corresponding image data DT (14) to DT ( 25) are stored respectively. As a result, in step ST4, the reception waiting sequence number SNw “14” matches the stored sequence number SNm (= 14), so the process proceeds to step ST8.

  In step ST8, the corresponding image data DT (14) is read from the data storage unit 4n and output to the image processing unit 4c. In the next step ST15, the reception waiting sequence number SNw is updated to “15”, and the process returns to step ST4. In step ST4, when the updated reception waiting sequence number SNw “15” matches the stored sequence number SNm (= 15), the process proceeds to step ST8 again. In this manner, steps ST4, ST8, and ST9 are repeated until the storage sequence number SNm “25” is targeted. As a result, the image processing of the image data DT (13) to DT (25) is performed only on the monitor slave unit 4 side, and the image processing that was interrupted due to the occurrence of a reception error is resumed.

  When the image data DT (25) is output to the image processing unit 4c and the reception waiting sequence number SNw is updated to “26”, the stored sequence number SNm corresponding to the number disappears in the number storage unit 4m. In step ST4, it is determined that there is a mismatch, and the flow of FIG. 10 ends. In the control for executing the flow of FIG. 13 for performing the transmission process, it is determined in step ST11 that the reception waiting sequence number SNw at the time of transmitting the current retransmission control signal is updated, the process proceeds to step ST15, and the flow of FIG. To do. Thereafter, the transmission / reception processing according to the flows of FIGS. 10 and 13 is performed.

  The present invention has been described with reference to the preferred embodiments. However, as those skilled in the art can easily understand, the present invention is not limited to such embodiments, and the gist of the present invention. As long as it does not deviate from the above, it can be appropriately changed. In addition, all the components shown in the above embodiment are not necessarily essential, and can be appropriately selected without departing from the gist of the present invention.

  The wireless communication system according to the present invention can continue data transmission / reception without requesting retransmission even if data transfer is performed by the relay unit before and after data transfer by the relay unit when wireless communication between the master unit and the slave unit is performed via the relay unit This is useful when a repeater is provided in wireless communication.

1 Base unit 1b Control unit 1i Frame processing unit 1j Radio unit 1m Number storage unit 1n Data storage unit 1o Buffer unit 2 Door phone slave unit 2b Control unit 3 Camera slave unit 3b Control unit 3i Frame processing unit 3j Radio unit 3n Buffer unit 4 Monitor Slave unit 4b Control unit 4i Frame processing unit 4j Radio unit 4m Number storage unit 4n Data storage unit 5 Relay unit 5b Control unit 5n Buffer unit

Claims (4)

A wireless communication system that performs wireless transmission and reception between a parent device and a child device,
A relay device that relays transmission / reception between the parent device and the child device;
The base unit transmits packets in numerical order,
The slave sets a reception waiting number setting unit that sets the number of the next packet to be received as a reception waiting number when the packets are received in numerical order, and updates the reception waiting number at a predetermined timing. A retransmission control unit for determining and transmitting a response signal requesting retransmission of the packet based on the determination result to the repeater ;
When the retransmission control unit determines that the reception waiting number has not been updated, it transmits a negative response ,
The base unit has a storage unit that sequentially stores the packets to be transmitted, and operates to discard an old packet and store a packet to be newly transmitted when the storage unit is full. Wireless communication system. The slave has a storage unit for storing the packet,
The retransmission control unit determines that the reception waiting number has not been updated and transmits a negative response when the packet is stored in the storage unit. Wireless communication system.   The wireless communication system according to claim 1, wherein the slave unit starts receiving a packet and sets the number of the first received packet as a reception waiting number. The parent device sends the frame number, the pre-Symbol handset, a wireless communication system according to claim 1, characterized in that to send a negative response in the own transmission permission frame which is determined based on the frame number .

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