JP2012029253A - Radio communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication device capable of maintaining communication while avoiding interference with other communication systems, and improving reliability of communication.SOLUTION: In a radio communication system dividing data to be transmitted and parallelly transmitting the data to reception stations using a plurality of radio channels, a control part performs: instructing each reception station to perform a carrier sensing for detecting the presence or absence of interference in the plurality of radio channels including used channels and spared channels every time a certain data transmission unit is transmitted and also performing the carrier sensing also in the own station; and totalling results of carrier sensing at the own station and reception stations to determine the presence or absence of interference in each of the channels, and transmission in a used channel is stopped and data that has been transmitted using the stopped radio channel is transmitted by a spared channels when there is interference in any of the used channels and there is no interference in the spared channel, and the data is transmitted so as to be distributed to other used radio channels when there is interference in the spared channel.

Description

  The present invention relates to a wireless communication device that divides transmission data into a plurality of pieces and transmits them in parallel using a plurality of wireless channels, and can maintain communication while avoiding interference with other communication systems, The present invention relates to a wireless communication apparatus that improves communication reliability.

[Description of Prior Art: FIG. 13]
In order to increase the speed of wireless communication, a method has been devised in which transmission data is divided and transmitted using a plurality of wireless channels.
A general wireless communication system will be described with reference to FIG. FIG. 13 is an explanatory diagram showing a configuration of a general wireless communication system.
Here, a wireless communication system capable of half-duplex communication between a transmitting station (master station) and a receiving station (slave station) is shown. For example, as shown in FIG. 100) and a plurality of receiving stations 1 (101), 2 (102), 3 (103), which perform broadcast communication from the transmitting station to the receiving stations 1, 2, 3 (one to three) Broadcast). The transmitting station is connected to the spectrum management server 104. The number of receiving stations is not limited to this.

In the communication group 105, the transmitting station transmits the transmission data b1, c1, and d1 to the receiving station 1, the receiving station 2, and the receiving station 3, respectively, by wireless communication. In the broadcast communication, the transmission data b1, c1 , And d1 are the same information.
Further, in the system of FIG. 13, in order to realize high-speed data communication, each transmission data is equally divided into three at the transmitting station and transmitted to each receiving station in parallel using three frequencies. To do. In the case of broadcast communication, all three frequencies used for each receiving station are common.

The spectrum management server 104 centrally manages the frequencies used in the wireless communication system, assigns frequencies that can be used for each communication, and notifies the transmitting station.
In the example described above, the three frequencies used in the broadcast communication are notified from the spectrum management server 104 to the transmitting station via the line a1.
Note that the spectrum management server 104 may be mounted on the transmitting station.
Further, the frequency used is known from the transmitting station to the receiving stations 1, 2, 3, but the means is arbitrary and is not defined here.
Furthermore, not the transmitting station but any one of the receiving stations 1, 2, 3 may be equipped with a communication function with the spectrum management server 104.
Further, when there are a plurality of communication groups in the communication system, the spectrum management server 104 can also manage radio channels for communication of the plurality of communication groups.

[Interference with other systems]
By the way, when other radio communication system 106 uses the same frequency as communication group 105, interference e1 occurs.
As the interference e1, when the communication in the communication group 105 becomes an interference source and causes radio interference to the other wireless communication system 106 (giving interference), the other wireless communication system 106 becomes an interference source and the communication group 105 Communication may cause radio interference (interference).
A case where communication is interrupted by an interference radio wave from another malicious wireless communication system is also included in the interference.

[Related technologies]
As a technique related to the wireless communication apparatus, there is JP-A-2005-252937 “Wireless communication apparatus and wireless communication method” (Applicant: Harada Kogyo Co., Ltd., Patent Document 1).
In Patent Document 1, packet data generated by a wired communication unit is divided into MAC frame data units, converted and stored, the MAC data is transferred via a bus, and a wireless module transmits a MAC frame for each wireless channel. A wireless communication device is described that receives separately as a data unit, converts each into an analog wireless signal, and separately transmits a plurality of converted analog wireless signals as radio waves having different polarizations for each wireless channel.

JP-A-2005-252937

  However, the conventional wireless communication apparatus has a problem that sufficient consideration cannot be given to maintaining communication while avoiding interference with other systems.

  The present invention has been made in view of the above circumstances, and provides a wireless communication apparatus capable of maintaining communication and improving communication reliability while avoiding interference with other systems. For the purpose.

  The present invention for solving the problems of the above-described conventional example is a wireless communication apparatus that divides transmission data and transmits it to a plurality of receiving stations in parallel using a plurality of frequencies, wherein the power level of the received signal A carrier sense unit that detects a carrier, and each time data of a predetermined transmission unit is transmitted, the carrier sense unit uses a plurality of frequencies used for transmission / reception and a spare frequency set as a spare for a carrier. In addition to outputting an instruction to perform sensing, an instruction to perform carrier sensing for a plurality of usage frequencies and backup frequencies is transmitted to the receiving station, and based on the result of carrier sensing in the carrier sensing unit and the result of carrier sensing received from the receiving station Thus, the presence or absence of interference is determined for a plurality of usage frequencies and standby frequencies, and as a result of the determination, interference is present in one of the plurality of usage frequencies. If there is no interference in the backup frequency, the use of the use frequency with the interference is stopped, and the data transmitted at the stopped frequency is transmitted at the backup frequency. When there is interference in the heel standby frequency, a control unit that stops the use of the use frequency with the interference, distributes the data transmitted at the stopped frequency to use frequencies other than the stopped frequency, and transmits the data. It is characterized by having.

  According to the present invention, a wireless communication apparatus that divides transmission data and transmits the data to a plurality of receiving stations in parallel using a plurality of frequencies, and performs carrier sensing that detects a power level of a received signal. And each time data of a predetermined transmission unit is transmitted, the carrier sense unit outputs an instruction to perform carrier sense for a plurality of use frequencies used for transmission and reception and a backup frequency set for backup, An instruction to perform carrier sense for a plurality of use frequencies and backup frequencies is transmitted to the receiving station, and a plurality of use frequencies and backup frequencies are determined based on the carrier sense result in the carrier sense unit and the carrier sense result received from the receiving station. The presence or absence of interference is determined, and as a result of the determination, there is interference at any of the plurality of used frequencies, and there is no interference at the standby frequency In this case, the use of the use frequency having the interference is stopped, the data transmitted at the stopped frequency is transmitted at the backup frequency, and as a result of the determination, there is an interference between the use frequency and one of the use frequencies. In this case, since the wireless communication device has a control unit that stops the use of the use frequency with the interference and distributes the data transmitted at the stopped frequency to the use frequency other than the stopped frequency and transmits the data. Even in an environment where there is a risk of mutual interference with other systems, it is possible to reliably transmit information using a frequency without interference, maintain communication, and improve communication reliability There is.

1 is a configuration block diagram of a wireless communication apparatus according to a first embodiment. It is explanatory drawing which shows the operation | movement sequence before the communication start in the system using a 1st radio | wireless communication apparatus. It is explanatory drawing which shows the frame format structure of each channel used with the sequence shown in FIG. It is explanatory drawing which shows the operation | movement sequence after the communication start in the system using a 1st radio | wireless communication apparatus. FIG. 5 is an explanatory diagram showing a frame format configuration of each channel used in the sequence of FIG. 4. It is a schematic explanatory drawing which shows the operation state for every radio channel accompanying the data transmission in the 1st radio | wireless communication apparatus, and the switching of a utilization frequency. FIG. 6 is a schematic explanatory diagram illustrating an operation state at each frequency when interference occurs even in a standby radio channel in the first radio communication device. It is explanatory drawing which shows the operation | movement sequence in the system using a 2nd radio | wireless communication apparatus. It is explanatory drawing which shows the frame format structure of an error packet / carrier sense request channel and an error packet / carrier sense response channel. It is a schematic explanatory drawing which shows the operation state for every radio | wireless channel in a 2nd radio | wireless communication apparatus. It is explanatory drawing which shows the operation | movement sequence in the system using a 3rd radio | wireless communication apparatus. It is a schematic explanatory drawing which shows the operation state for every radio | wireless channel in a 3rd radio | wireless communication apparatus. It is explanatory drawing which shows the structure of a general radio | wireless communications system.

[Outline of the embodiment]
Embodiments of the present invention will be described with reference to the drawings.
The wireless communication apparatus according to the embodiment of the present invention divides transmission data and transmits it in parallel to a receiving station using a plurality of wireless channels, and each time a certain data transmission unit is transmitted, Instruct each receiving station to perform carrier sense to detect the presence or absence of interference for each radio channel, and also perform carrier sense at the own station, aggregate the results of carrier sense of the own station and the receiving station, and interfere with each radio channel. The use of a wireless channel that may cause interference is stopped, and the transmission data transmitted on the stopped wireless channel is transmitted on a preset backup wireless channel. Data can be reliably transmitted without using a wireless channel that may cause interference, communication can be maintained, and communication reliability can be improved.

  In addition, the radio communication apparatus according to the present embodiment always performs carrier sense for a preset spare radio channel, and when there is a possibility of interference with the radio channel being used, the radio communication apparatus can interfere with the spare radio channel. If there is no possibility, it transmits using a spare radio channel, and when there is a possibility of interference in the spare radio channel, transmission data is distributed to other radio channels in use and transmitted. Data can be reliably transmitted without using a wireless channel that may cause interference, communication can be maintained, and communication reliability can be improved.

  In addition, in the wireless communication apparatus according to the embodiment of the present invention, only when the receiving station detects the presence of an error in the received packet and the transmitting station receives data indicating that there is an error from the receiving station. The carrier sense for the next data transmission unit that follows is executed, and the decrease in frequency utilization efficiency due to the carrier sense can be reduced.

[Radio communication apparatus according to first embodiment]
The wireless communication apparatus (first wireless communication apparatus) according to the first embodiment of the present invention is used as a transmitting station or a receiving station in the same system (this system) as the wireless communication system shown in FIG. Hereinafter, description will be made assuming that the system configuration shown in FIG. 13 is used.
As shown in FIG. 13, the communication group 105 includes a transmitting station that is a master station and receiving stations 1, 2, and 3 that are slave stations. Perform heavy communication. In addition, a spectrum management server 104 that manages radio channels is provided. The number of receiving stations is not limited to this.
In this system, it is assumed that one frequency is assigned to one radio channel.

[Configuration of First Wireless Communication Device: FIG. 1]
Next, the configuration of the wireless communication apparatus according to the first embodiment will be described with reference to FIG.
FIG. 1 is a configuration block diagram of a wireless communication apparatus according to the first embodiment. The first wireless communication device is a wireless device used as a transmitting station or receiving station 1, 2, 3.
As illustrated in FIG. 1, the first wireless communication apparatus includes a transmission / reception processing unit 200 and a control unit 201.
The control unit 201 controls the entire apparatus, and includes a storage unit and a processing unit. The processing unit activates a processing program stored in the storage unit and performs various controls. The control unit 201 outputs transmission / reception control and an instruction of a radio channel to be used as processing control information to the transmission / reception processing unit 200.

  In particular, as a feature of this system, the control unit 201 determines whether or not there is interference for each of the currently used and standby radio channels, and if there is interference in any of the radio channels, the standby radio without interference is used. The transmission / reception processing unit 200 is controlled to transmit / receive using a channel or another wireless channel in use.

In addition, since this system performs half-duplex communication, data cannot be transmitted or received from both sides at the same time. Therefore, each wireless transmission / reception apparatus performs transmission or reception operation by dividing time. When the transmission mode is set as the operation mode, the transmission operation is performed, and when the reception mode is set, the reception operation is performed.
The control unit 201 outputs an instruction to switch the transmission mode / reception mode in a time division manner to the transmission / reception processing units 200 of the transmission station and the reception stations 1, 2, and 3. As a result, the transmitting station and the receiving stations 1, 2, and 3 realize bidirectional communication by switching the communication direction in a time division manner.

  The transmission / reception processing unit 200 of the wireless communication apparatus performs processing such as modulation / demodulation, error detection, and error correction associated with transmission / reception in accordance with an instruction (processing control information) from the control unit 201. Frame processing means 203, data transmission means 204, error detection means 208, and automatic retransmission control means 209 are provided.

Further, the data transmission means 204 is provided for each wireless channel to be used. In the example of FIG. 1, the data transmission processing means corresponding to each of four systems (three used wireless channels and one spare wireless channel). 204-1 to 204-4. The use radio channel (use radio frequency) and the backup radio channel (standby frequency) are set by the control unit 201 and normally transmit on the use radio channel, but transmit on the backup radio channel as necessary. For the operation. The spare system is indicated by a broken line in the figure.
That is, the wireless device shown in FIG. 1 is a wireless device having four processing systems.

[Each part of the transmission / reception processor 200: FIG. 1]
Each component of the transmission / reception processing unit 200 of the wireless communication apparatus will be described.
In the transmission mode, the disassembling / assembling unit 202 performs an equal dividing process of dividing data such as an electronic mail and an electronic file into a plurality of pieces, and outputs the divided data.
In the reception mode, the divided data is assembled into one data, and the assembled data is output.

  Here, the number of divisions in the disassembling / assembling means 202 corresponds to the number of radio channels, and is designated by the process control information from the control unit 201. In this system, the number of divisions is 3, and transmission is performed in parallel using three frequencies (wireless channels).

In the transmission mode, the frame processing unit 203 generates each channel having a predetermined frame format configuration from the divided data and control information based on the processing control information. The frame format will be described later.
Here, the frame processing unit 203 sequentially generates eight types of channels in accordance with an operation sequence to be described later for each of the three divided data, and transmits the three channel strings to the data transmission in use. Output simultaneously to the means 204 (usually 204-1 to 204-3).

  Control information is information handled by an application such as e-mail located in a higher layer, and includes a message number (a number assigned to a communication unit such as e-mail), a transmission data size such as e-mail, and a destination of broadcast Number, source IP address, and one or more destination IP addresses.

  In the reception mode, the frame processing unit 203 extracts the divided data and control information from the reception data (channel sequence) for each frequency output from each data transmission unit 204 and outputs the extracted data.

  Further, the frame processing unit 203 creates error packet response information in an error packet response channel (FIG. 5 (g)) to be described later based on the information of the automatic retransmission control signal from the automatic retransmission control unit in the reception mode. The synchronization information and setting information are added and output to the data transmission means 204. It also stores and manages data block numbers and message numbers related to retransmission.

The data transmission unit 204 includes an error correction unit 205, a modem unit 206, a radio unit 207, and a carrier sense (power detection) unit 210.
In the transmission mode, error correction means 205 performs error correction coding on the channel string information, and outputs the data string after error correction coding to modulation / demodulation means 206.
In the reception mode, the error correction unit 205 performs error correction processing on the demodulated reception data sequence from the modulation / demodulation unit 206, and outputs a reception data sequence (reception channel sequence) after error correction.

In the transmission mode, the modulation / demodulation means 206 includes modulation / demodulation method type information (BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), 16QAM (16 Quadrature Amplitude Modulation), etc. included in the processing control information from the control unit 201. Using the method specified by the identification information), the data of the data string after error correction coding is modulated, and the modulated signal is output to the radio section 207.
Further, in the reception mode, the modulation / demodulation means 206 performs demodulation processing on the baseband reception signal output from the radio unit 207 based on modulation / demodulation method type information specified by the control unit 201, and outputs demodulated data. .

  In the transmission mode, the radio unit 207 performs band limitation on the modulated signal based on the use frequency information included in the processing control information from the control unit 201, performs band limitation by transmission filter processing, performs orthogonal modulation processing, and performs carrier modulation. The frequency is up-converted, amplified by a power amplifier, and transmitted radio waves are transmitted through a transmission antenna.

In the reception mode, the radio unit 207 receives incoming radio waves via a reception antenna and an LNA (Low Noise Amplifier) based on the use frequency information from the control unit 201, performs orthogonal demodulation processing, and performs base demodulation. Down-converted to band frequency, band-limited by reception filter processing, and output baseband received signal.
Here, each of the constituent means in the wireless unit 207 is configured to be able to transmit / receive by switching the frequency based on the transmission / reception frequency designated by the control unit 201.

In the transmission mode, the error detection unit 208 detects the presence or absence of an error when an error packet response from the receiving station is input from the frame processing unit 203. If the error detection unit 208 is “error present”, the automatic retransmission control unit An error detection signal is output to 209. The error packet response information includes receiving station designation information, a data block number, and a message number.
Further, in the reception mode, the error detection unit 208 receives an error packet request channel from the transmitting station, and when a received packet corresponding to the error packet request information is input from the frame processing unit 203, an error is detected. The error packet response information is output to the frame processing means 203. Further, when there is an error, an error detection signal is output to the automatic retransmission control means 209.

Automatic repeat control (ARQ) means 209 is means for performing automatic retransmission control, and operates in cooperation with the frame processing means 203 by an automatic retransmission control signal.
In the transmission mode, the automatic retransmission control unit 209 stores information included in error packet request information in an error packet request channel, which will be described later. When an error detection signal is input from the error detection unit 208, the retransmission data channel And an automatic retransmission control signal for retransmitting the corresponding packet is output to the frame processing unit 203.

  In the reception mode, the automatic retransmission control unit 209 makes an automatic retransmission request when an error detection signal is input from the error detection unit 208. Therefore, the automatic retransmission control unit 209 includes an automatic retransmission including receiving station designation information, data block number, and message number The control signal is output to the frame processing means 203.

  In this system, it is assumed that the wireless device returns an error response to all packets in the data block in the reception mode.

The carrier sense (power detection) means 210 detects the power level of the received signal input from the radio unit 207 in order to check the presence / absence of interference for the frequency to be transmitted.
That is, in the radio of this system, the radio unit 207 first receives the frequency to be transmitted, detects the power level by the carrier sense unit 210, and outputs the detection result to the frame processing unit 203 and / or the control unit 201. To do.

The carrier sense means 210 detects the result of carrier sense (carrier sense data information) as soft value information or hard value information as will be described later.
Then, in the transmitting station, the carrier sense means 210 outputs the result of carrier sense of soft value information or hard value information to the control unit 201.
In the receiving station, the carrier sense unit 210 outputs the result of the carrier sense to the frame processing unit 203, and the frame processing unit 203 generates carrier sense response data including soft value information or hard value information. The data is transmitted as a channel to the transmitting station via the data transmission means 204.
The carrier sense process will be described later.

As a feature of the first wireless communication apparatus, when a reception signal having a carrier level equal to or higher than a certain level is detected, the control unit 201 of the transmitting station determines that the wireless channel has a risk of interference, and uses it. If there is no risk of interference in the backup radio channel (if there is an empty channel), an instruction is output to the transmission / reception processing unit so as to switch to the backup radio channel for transmission.
In addition, if the standby radio channel is also at risk of interference (if there is no available channel), an instruction is output so that transmission is performed by distributing to the remaining available radio channels.
As a result, the radio of this system can avoid interference / interference (including interference).
In this system, the carrier sense is described on the assumption that the transmitting station performs the initiative, but the receiving may be performed by the receiving station or the spectrum management server. Or it is good also as a structure which provides a sensing exclusive station and manages carrier sense here.

[Career sense]
Next, carrier sense which is a characteristic part of the wireless communication apparatus will be described.
As a method of carrier sensing, there are independent sensing in which only the transmitting station performs carrier sensing, and cooperative sensing in which all the stations (transmitting station and receiving station) in the group perform carrier sensing.
In single sensing, if there is an obstacle between the transmitting station that performs carrier sense and the interfering station (the station that is the subject of interference / interference), the interfering station can be detected from the transmitting station. Therefore, there is a possibility that the transmitting station starts transmission and causes interference (referred to as a hidden terminal problem).

  In cooperative sensing, in addition to the transmitting station, carrier sensing is performed also at receiving stations arranged at various places, and the sensing results are aggregated by the transmitting station, and the presence / absence of an interfering station is comprehensively determined from the results. Therefore, the hidden terminal problem does not occur in cooperative sensing.

In the present system, it is assumed that cooperative sensing is performed and the control unit 201 of the transmitting station controls the use frequency.
The types of carrier sense results (sensing information) reported from each station include the received signal level measured by each station (transmitting station and receiving station) (for example, soft value information expressed in 32 bits) and received by each receiving station. There is a result (hard value information expressed by “0” or “1”) in which the presence / absence of an interference signal is determined by comparing the signal level with a predetermined threshold. Which information is used is preset in each station.

Then, the sensing information of each station is aggregated (aggregated) at the transmitting station, and the presence / absence of an interference signal is determined. At this time, when soft value information is used, for example, based on the sensing information of all stations, the average value, sum, etc. are calculated and compared with a predetermined threshold value to determine the presence or absence of an interference signal. That is, it is determined that there is no interference if the average value or the sum is equal to or less than the threshold value, and it is determined that there is interference if the threshold value is exceeded.
In the case of hard value information, if even one piece of aggregated sensing information indicates the presence of an interference signal, it may be determined that there is an interference signal and transmission is not performed.

[Operation during carrier sense: Fig. 1]
Next, the operation of the wireless communication device during carrier sense will be described.
The carrier sense process is executed by the operation of each processing unit based on the control of the control unit 201 as in the other processes in the wireless communication apparatus.
First, the transmitting station transmits a carrier sense request channel (FIG. 3A), which will be described later, to the receiving station before starting communication, and the transmitting station itself also performs carrier sensing. The carrier sense request channel is generated by the frame processing unit 203 and transmitted via the data transmission unit 204. The carrier sense request channel includes data indicating the carrier sense target frequency and the like.

  In the receiving station, when receiving the carrier sense request channel, the control unit 201 instructs the carrier sense unit 210 on the frequency of the carrier sense target radio channel (in this system, three use radio channels and one spare radio channel). ), Each carrier sense means 210 measures the reception level of the baseband received signal that is output from each radio section 207, and the frame processing means 203 uses the measurement result of the soft value information or the hard value information as carrier sense data information. Output to.

  At the receiving station, the frame processing unit 203 inserts soft value information or hard value information, which is carrier sense data information, into a carrier sense response channel (FIG. 3B), which will be described later, via the data transmission unit 204. To the transmitting station.

In the transmitting station, the carrier sense response channel transmitted from the receiving station is received, and the frame processing means 203 extracts the carrier sense data information and outputs it to the control unit 201.
In the transmitting station, the carrier sense means 210 outputs carrier sense data information to the control unit 201.

The control unit 201 of the transmitting station aggregates the carrier sense data information measured by the own station and the carrier sense data information received from a plurality of receiving stations, and interferes with cooperative sensing using a preset method as described above. Determine the presence or absence of a signal.
In this way, carrier sense processing of the present system is performed.

  In this embodiment, carrier sense is performed every time transmission of a data transmission unit is completed after communication is started. At this time, the carrier sense request channel and the carrier sense response channel are transmitted at one or a plurality of use frequencies. Is done. It is not transmitted on the backup radio channel.

[Operation sequence before starting communication: Fig. 2]
Next, an operation sequence before the start of communication in a system using the first wireless communication apparatus will be described with reference to FIG. FIG. 2 is an explanatory diagram showing an operation sequence before starting communication in a system using the first wireless communication apparatus.
In this system, before starting communication, carrier sense is performed using a frequency set in advance as a common control frequency within the group among the three used radio channels (frequencies) F1, F2, and F3. Based on the result, a frequency to be used is determined and a process of notifying each receiving station is performed.

In the example of FIG. 2, the intra-group common control frequency is F1. Therefore, the sequence of FIG. 2 is performed only by F1. The frequency F1 is not a dedicated frequency used only for common control within the group, but is also used for data transmission after the start of communication.
Here, it is assumed that the intra-group common control frequency F1 can be used before the start of communication.
In actual operation, another backup frequency is prepared as a common control frequency within the group, and when communication at the frequency F1 is not established due to interference or the like before the start of communication, a retry is performed at the backup frequency. The intra-group common control frequency and the backup frequency are assumed to be known in the group in advance.

As shown in FIG. 2, the transmitting station transmits a carrier sense request channel to the receiving stations 1, 2, and 3 using the intra-group common control frequency F1 (305).
Receiving the carrier sense request channel, each receiving station 1, 2, 3 executes carrier sense for the designated frequency (306). Further, the transmitting station also performs carrier sense in itself (306). The frequency at which carrier sense is performed is a frequency (F1, F2, F3, F4) that the transmission station is permitted to use from the spectrum management server.
The carrier sense execution time is set to an appropriate length capable of detecting radio waves from other wireless communication systems according to the use frequency bandwidth.

Then, after performing carrier sense, each receiving station transmits a carrier sense response channel including carrier sense data information that is a result of carrier sense.
Since this system is half-duplex communication (transmitting station and receiving station transmit using the same frequency F1), each receiving station switches to a transmission state to return a carrier sense response channel after performing carrier sensing. (However, the reception mode state is maintained).

At the time of the carrier sense response, since the receiving station 1, the receiving station 2, and the receiving station 3 use the same frequency (F1), the carrier sense response channel is transmitted in a time division manner.
Here, the transmission timing of the carrier sense response channel from the receiving stations 1, 2, and 3 will be described.
The receiving station 1 transmits a carrier sense response channel to the transmitting station T1 after completion of the carrier sense execution (307).

  T1 is the time from the completion of carrier sense execution until the receiving station 1 starts transmitting a carrier sense response, and data processing for switching from the reception state to the transmission state at the receiving station 1 and for generating a carrier sense response channel It takes time to complete. When the transmission of the carrier sense response channel ends, the receiving station 1 returns to the reception state again.

The transmitting station enters a reception mode after completion of carrier sense execution and waits for a carrier sense response channel from the receiving station.
Then, the transmitting station determines from which receiving station the carrier sense response is based on the reception timing of the carrier sense response channel.
That is, if the reception timing t (time from completion of carrier sense execution to reception) is T1 <t ≦ T1 + T2 (between time A and time B in FIG. 2), it is recognized as a response from the receiving station 1 ( 308).
T2 is the time required for transmission of the carrier sense response, and in addition to the data transmission time from the receiving station, a margin for absorbing the delay time difference in the propagation path due to the difference in the location of each receiving station is provided. Contains.

The receiving station 2 transmits a carrier sense response channel to the transmitting station after the completion of the carrier sense execution (T1 + T2) so as not to interfere with the transmission of the receiving station 1 (309). When the transmission of the carrier sense response channel is completed, the receiving station 2 returns to the reception state again.
If the timing t at which the carrier sense response is received is T1 + T2 <t ≦ T2 × 2 (between time B and time C in FIG. 2), the transmitting station recognizes the response from the receiving station 2 (310).

Similarly, the receiving station 3 transmits the carrier sense response channel to the transmitting station after (T1 + T2 × 2) has elapsed from the completion of the carrier sense execution (311), and returns to the receiving state.
If the timing t of receiving the carrier sense response is T1 + T2 × 2 <t ≦ T2 × 3 (between time C and time D in FIG. 2), the transmission station recognizes that the response is from the reception station 3 (312). .

  Then, as described above, the transmitting station determines an available frequency (radio channel) with no interference from the carrier sense results of the transmitting station itself and each of the receiving stations 1, 2, and 3. A standby radio channel is determined and notified to each of the receiving stations 1, 2, and 3 using a use frequency setting channel (313).

Here, it is assumed that F1, F2, and F3 are set as the use radio channels, and F4 is set as the backup radio channel.
In this example, description will be made assuming that the number of spare radio channels is only one (F4). However, by preparing a plurality of spare radio channels, the reliability of communication can be further improved.

[Frame format configuration (1): FIG. 3]
Here, the frame format configuration of each channel used in the sequence of FIG. 2 will be described with reference to FIG. FIG. 3 is an explanatory diagram showing the frame format configuration of each channel used in the sequence shown in FIG.
[Common part of each channel]
First, common portions of the channels shown in FIGS. 3A to 3C will be described.
The synchronization information is a synchronization pattern for detecting the start point of each channel. On the other hand, a synchronization pattern for demodulating the received signal is inserted by the modulation / demodulation means 206.
The setting information includes control channel type information (carrier sense billing, carrier sense response, use frequency setting) and modulation / demodulation method type information (identification information such as BPSK, QPSK, 16QAM) for the data packet. The synchronization information and the setting information are the same for other control channels and data channels described later, and the other information will be described below.

  The modulation / demodulation method applied to the control information shown in (a) to (c) is fixed. For example, BPSK having the strongest noise resistance is used. This is because control information is more important than data packets. In addition, the error correction code is added to the control information by the error correction means 205 and then packed in the field of each channel.

[Carrier Sense Request Channel: FIG. 3 (a)]
As shown in FIG. 3 (a), the carrier sense request channel is for the transmitting station to instruct the receiving station to execute carrier sense, and the carrier sense request source IP address, the number of carrier sense request destinations ncs, and the carrier sense request. The destination IP address 1, ..., ncs, the number of carrier sense target frequencies mcs, and the carrier sense target frequency 1, ..., mcs are included.
Here, as described above, since the carrier sense request is made by the transmitting station, the carrier sense requesting source IP address is set to the address of the transmitting station.

  The carrier sense billing number ncs is assumed to be coordinated sensing by all stations in the group in this system, and is set to ncs = 3 (the same number as the number of receiving stations). Therefore, the addresses of the receiving station 1, the receiving station 2, and the receiving station 3 are set as the billing destination IP addresses 1,.

The number mcs of carrier sense target frequencies is for instructing the target frequency for carrier sense, and before the start of communication, the number of used radio channels (here, three of F1, F2, and F3) and the number of spare radio channels The sum (here, one of F4) (mcs = 4 in this example) is set, and mcs = 1 is set after the start of communication.
The carrier sense target frequencies 1,..., Mcs are set to the values of the frequencies F1, F2, F3, and F4 before the start of communication, and any of the frequencies F1, F2, F3, and F4 after the start of communication. Value is set.

Note that in the case of single sensing in which carrier sensing is performed only at the transmitting station, ncs = 0 is set, and fields subsequent to the billing destination IP address 1,..., Ncs are not transmitted.
Further, when carrier sense is not executed, for example, −1 is set in ncs for transmission, and the fields after the billing destination IP addresses 1,..., Ncs are not transmitted.

[Carrier sense response channel: FIG. 3B]
As shown in FIG. 3 (b), the carrier sense response channel is one in which the receiving station notifies the transmitting station of the result of carrier sense, and carrier sense response information and carrier sense data information 1, ..., mcs. including. Here, the carrier sense response information includes the identification number of the receiving station (the number indicating the order set in the carrier sense request destination IP address 1, ..., ncs of the carrier sense request channel), and the carrier sense target frequency. Including the number mcs (same as the number instructed by the transmitting station).

  The carrier sense data information 1, ..., mcs includes the received signal level (for example, soft value information represented by 32 bits) measured at each receiving station or the received signal level at each receiving station. Is compared with a predetermined threshold value to determine the presence or absence of a signal (hard value information represented by 0 or 1).

[Use frequency setting channel: FIG. 3 (c)]
As shown in FIG. 3 (c), the use frequency setting channel is for the transmitting station to notify the receiving station of the use frequency, the transmission data size, the message number for identifying the e-mail or file to be transmitted, the use It includes the number of channels m, initial setting / setting change information, and usage frequencies 1, ..., m.
Here, the transmission data size is the size (data amount) of transmission data before division, and the number m of used channels is the number of radio channels (frequencies) used for parallel transmission. In this example, m = 3 is set. .

The initial setting / setting change information is used for the initial setting of the used frequency setting channel before the start of communication, or for changing the radio channel setting based on the result of carrier sense described later. It is the identification information which shows.
The use frequencies 1,..., M are carrier frequencies of radio signals of respective radio channels that have been used as a result of determination based on carrier sense.

[Widely known backup radio channel]
Here, a well-known method of the backup radio channel to each receiving station will be described.
The receiving station recognizes the backup radio channel based on the carrier sense request channel (FIG. 3A) and the use frequency setting channel (FIG. 3C).
Specifically, the receiving station uses the carrier sense target frequencies 1,..., Mcs (four frequencies F1, F2, F3, and F4 in this example) included in the carrier sense request channel and the use frequency setting channel. The difference (F4 in this example) between the included use frequencies 1,..., M (three frequencies F1, F2, and F3 in this example) is recognized as a backup radio channel.

As another method, a field for transmitting the number of spare radio channels and the value of each frequency may be added to the use frequency setting channel.
Each receiving station operates in a constantly receiving state (including carrier sense execution) for the backup radio channel in order to respond to changes in the used radio channel that are instructed from time to time by the transmitting station.

[Control channel before communication starts]
As described above, before the start of communication, the carrier sense request channel, the carrier sense response channel, and the use frequency setting channel are transmitted only at the frequency (here, F1) assigned for the common control within the group. This is because carrier sense is performed using the common control frequency in the group before communication is started, that is, before data transmission is started, and the use frequency is determined based on the result, and the use frequency is made known to each receiving station. It is to do.

[Operation sequence after start of communication (change from F1 to F4): FIG. 4]
Next, an operation sequence after the start of communication in the system using the first wireless communication device will be described with reference to FIG. 4 when the use frequency is changed from F1 to F4. FIG. 4 is an explanatory diagram showing an operation sequence after the start of communication in the system using the first wireless communication apparatus. FIG. 4 shows a sequence following (a), (b), (c), and (d) of FIG.
As shown in FIG. 3, when the use frequency is notified from the transmitting station to the receiving stations 1, 2, and 3 by the use frequency setting channel, the following frequencies are simultaneously used in parallel at the use frequencies F1, F2, and F3. Communication takes place. FIG. 4 shows the sequence in F1, but the sequence in F1 switches to F4 in the middle. Otherwise, the same applies to F2 and F3.

The transmitting station transmits a channel setting channel to each receiving station (314).
The configuration of the line setting channel will be described later, but includes a source IP address, the number of destinations, and a destination IP address. All the receiving stations in the wireless communication network (wireless communication system) receive the circuit setting channel, and if their own IP address is included in the destination IP address, recognize that it is a transmission target and then Continue communication, otherwise ignore subsequent communication.
Here, the receiving station 1, the receiving station 2, and the receiving station 3 are transmission targets (destination) from the transmitting station.

  Next, the transmitting station transmits a data channel to each receiving station (315). The data channel includes a data packet for one data block.

Each time transmission of a data packet for one data block is completed, sequences 316 to 322 are executed as an automatic retransmission control operation.
The transmitting station transmits an error packet request channel to each receiving station in order to confirm whether or not the transmitted data packet has been transmitted without error (316).
As in the case of the carrier sense response, since it is half-duplex communication, each receiving station switches to the transmission state to return the error packet response channel when receiving the error packet request channel (however, the reception mode state is maintained). .

At the time of error packet response, similarly to the case of carrier sense response, the receiving station 1, the receiving station 2, and the receiving station 3 use the same frequency, so it is necessary to transmit the error packet response channel to the transmitting station in a time division manner. Similar to the carrier sense response, the transmission timing at each receiver is set in the system in advance.
Here, first, the receiving station 1 transmits an error packet response channel to the transmitting station T3 after completion of receiving the error packet request channel (317). T3 includes time required for data processing for switching from reception to transmission state and generating an error packet response channel. When the transmission of the error packet response channel ends, the receiving station 1 returns to the reception state again.

  As in the case of receiving the carrier sense response, the transmitting station recognizes from which receiving station the response is based on the reception timing of the error packet response channel (318, 320, 322).

  Since the receiving station 2 transmits after receiving the response from the receiving station 1 at the transmitting station, it transmits the packet response channel to the transmitting station T3 + T4 after the reception of the error packet request channel is completed (319). T4 is the time required for transmission of the error packet response, and in addition to the data transmission time from the receiving station, a margin for absorbing the delay time difference in the propagation path due to the difference in the location of each receiving station is provided. Contains. When the transmission of the packet response channel is completed, the receiving station 2 returns to the reception state again.

Similarly, the receiving station 3 transmits a packet response channel to the transmitting station T3 + T4 × 2 after the reception of the error packet request channel is completed (321).
Then, the transmitting station detects the presence / absence of an error packet based on the received error packet response channel, and if there is an error (323), retransmits the data (336).

Next, carrier sense sequences 324 to 331 are executed in order to confirm the presence or absence of interference for each frequency.
The transmitting station transmits a carrier sense request channel instructing carrier sense execution using one or a plurality of frequencies F1, F2, and F3, which are currently used frequencies, and carries out a carrier sense response in a time division manner. Receive a channel. Since the frequency F4 is a spare frequency at this time, the carrier sense request channel is not transmitted and no response is received.

Here, a method of transmitting / receiving the carrier sense request / response channel will be described.
The first method is to transmit the carrier sense request channel for the frequencies F1, F2, F3, and F4 using only the frequency F1, and receive the carrier sense response channel using only F1.
In other words, in the first method, the carrier sense request transmission and the carrier sense response are not performed at the other utilization frequencies F2 and F3.

  The second method is to transmit a carrier sense solicitation channel for frequency F1 and backup frequency F4 at frequency F1, receive a carrier sense response channel for F1 and F4, and solicit carrier sense for F2 at frequency F2. Response channel transmission / reception is performed, and carrier sense request / response channel transmission / reception for F3 is performed at frequency F3.

The third method is to perform transmission / reception of carrier sense request / response channels for F1, F2, F3, and F4 using the use frequencies F1, F2, and F3, respectively.
Although this method is redundant because all the frequencies used are transmitted and received, it is redundant, but it can improve reliability.
In this system, it is determined in advance which method is used to transmit / receive the carrier sense request / response channel between the transmitting station and the receiving station. Also, the frame format shown in FIGS. 3A and 3B is a general-purpose format that can correspond to any of the first to third methods.

The receiving stations 1, 2, and 3 perform carrier sense for F1, F2, F3, and F4 according to the carrier sense request channel received at one or more of the frequencies F1, F2, and F3, and request carrier sense. Using the frequency at which the channel is received, the carrier sense response is transmitted in a time division manner by shifting the timing for each receiving station.
Then, the transmitting station checks the presence / absence of interference for the use radio channels F1, F2, and F3 and the backup radio channel F4 based on its own carrier sense result and the received carrier sense result.

  If it is determined that there is no interference as a result of carrier sense, data channel transmission (315) to carrier sense response channel reception (331) are repeated for the next data block.

On the other hand, the processing when the frequency F1 is found to be an interference channel as a result of carrier sense will be described below.
When the control unit 201 of the transmitting station determines the presence or absence of interference for each of the frequencies F1 to F4 and determines that the frequency F1 is an interference channel, the control unit 201 determines whether or not F4, which is a backup radio channel, is an interference channel. If there is no interference in F4, a use frequency setting channel for changing the use frequency from F1 to F4 is transmitted to each receiver assuming that there is an empty channel (333).

Specifically, the transmitting station notifies the use frequency setting channel that the use frequency is changed from “F1, F2, F3” to “F2, F3, F4”.
At that time, the use frequency setting channel is transmitted using both the frequency before switching and the frequency after switching, and here, it is transmitted using F1 and F4. Each receiving station has already recognized that F4 is a backup radio channel, and is always in a receiving state at F4. Even if there is a risk of interference in the frequency F1, it is possible to reliably transmit the change in the use frequency by transmitting redundantly in F4.

  In addition, the transmitting station sets the initial setting / setting change information of the use frequency setting channel as “setting change” and transmits it, so that each receiving station changes the use frequency, and this communication is continued. Recognize that.

In order to further improve the reliability, redundancy can be increased by simultaneously transmitting the use frequency setting channel using the frequencies F2 and F3 during which another operation sequence is being executed.
Since the frequencies F2 and F3 are executing different operation sequences, it is necessary to synchronize with various channel transmissions. However, in the case of this system, the control unit 201 of the transmitting station performs an operation sequence at all frequencies. Since the transmission timing can be controlled, it is possible to synchronize between the used frequencies.
That is, in the operation sequence at the frequencies F2 and F3, if the use frequency setting channel is transmitted after waiting until the timing when the data block transmission ends, it is possible to transmit without causing interference between the use frequencies. It is.

As a result, the use frequency is changed from F1 to F4 at the transmitting station, the receiving station 1, the receiving station 2, and the receiving station 3 (334).
The F1 that is no longer used is then treated as a backup radio channel, and the transmitting station and the receiving stations 1, 2, and 3 always receive F1 (including carrier sense execution).

The transmitting station transmits the channel setting channel to each receiving station using the frequencies F2, F3, and F4 after a predetermined time considering the time required for the frequency switching process at each receiving station has passed (335). .
The contents of the line setting channel are the same information as the contents transmitted at the start of communication in F2 and F3, and for F4, the transmission data size is set to the data size of the remaining transmission in the operation sequence.

If there is an error packet in sequence 323, the transmitting station retransmits the corresponding data block through the retransmission data channel (336).
Here, the transmitting station retransmits the data to all receiving stations, and each receiving station validates the received data only when a packet for which retransmission is requested is sent, and does not request retransmission. If data is sent, ignore it.
If there is no packet error in receiving an error packet response, the transmitting station transmits a data channel having the next data block information, and then executes automatic retransmission control and carrier sense sequences 316 to 331.

When the predetermined communication is completed, the transmitting station transmits a channel release channel to the receiving stations 1, 2, and 3 and ends the communication (337).
In this way, the operation sequence in the present system is performed.

[Frame format configuration (2): FIG. 5]
Next, the frame format configuration of each channel used in the sequence of FIG. 4 will be described with reference to FIG. FIG. 5 is an explanatory diagram showing the frame format configuration of each channel used in the sequence of FIG.
Similar to the control channel shown in FIG. 3, each channel in FIG. 5 also includes synchronization information and setting information indicating the type of each channel, and description thereof will be omitted.
Further, each channel shown in FIG. 5 is generated and transmitted for each radio channel (utilization frequency).

[Line setting channel: FIG. 5 (d)]
The line setting channel notifies line setting information from the transmitting station to the receiving station. As shown in FIG. 5D, the transmission data size, the source IP address, the number of destinations n, the destination IP address 1, ..., n.
Here, in the transmission data size, the size of data transmitted for each radio channel (utilization frequency), that is, the transmission data size after division is set. The transmission source IP address is the address of the transmission station, the destination number n is 3, the transmission destination IP addresses 1,..., N are the IP addresses of the reception stations 1, 2, and 3, respectively. , 2,3.

[Data channel, retransmission data channel: FIG. 5 (e)]
The data channel and retransmission data channel transmit data and include a message number, data block number, data block size, final data block identification information, packet size, and data packet as shown in FIG. . Note that the type of the initial transmission or the retransmission is described in the setting information.
Data packets are packed with the number of packets per data block (data block size / packet size). Each packet includes a packet number, packet data, and an error detection code.

[Error packet request channel: FIG. 5 (f)]
The error packet solicitation channel is a request for the transmitting station to notify the receiving station of the presence or absence of an error packet in the received data, and includes error packet solicitation information as shown in FIG. The error packet request information includes receiving station designation information requesting a response, a data block number, and a message number.

[Error packet response channel: FIG. 5 (g)]
In the error packet response channel, the receiving station notifies the transmitting station of the presence or absence of an error packet in the received data in accordance with the error packet request channel. As shown in FIG. Including. The error error packet response information includes a data block number, a message number, and error packet information (error presence / absence information of all packets in the data block specified by the data block number).

[Line release channel: Fig. 5 (h)]
As shown in FIG. 5 (h), the channel cancellation channel is for the transmitting station to notify the receiving station of channel cancellation, and is composed of synchronization information and setting information.

[Operation at Each Frequency in First Wireless Communication Device (1): FIG. 6]
Next, an operation state for each wireless channel associated with data transmission and switching of the usage frequency in the first wireless communication device will be described with reference to FIG. FIG. 6 is a schematic explanatory diagram illustrating an operation state for each wireless channel associated with data transmission and switching of a use frequency in the first wireless communication apparatus.
FIG. 6 shows a state in which data transmission, automatic retransmission control (ARQ), and carrier sense are executed with the passage of time in each usage frequency. Here, the carrier sense before use of communication and the use frequency setting process are omitted and not shown.
In addition, in FIG. 6, for the sake of simplicity of illustration and description, it is described that each use frequency operates in units of time of t1, t2, and t3. However, in actual processing, Since an independent operation sequence (communication) is executed for each use frequency, it is not always necessary to operate in synchronization.

  As shown in FIG. 6, first, F1, F2, and F3 are set as usage frequencies, and the transmitting station and the receiving station transmit and receive data at F1, F2, and F3 (initial transmission, first transmission of the data block). )I do. Data transmission is not performed at the spare frequency F4, and carrier sensing is performed when a carrier sensing instruction is given in a constantly receiving state.

Data transmission is data block unit transmission, and each time transmission of one data block is completed, the transmitting station and the receiving station execute automatic retransmission control (ARQ) and carrier sense for the next data transmission.
As described above, the transmission station stops data transmission during execution of automatic retransmission control and carrier sense, and stops all transmissions of carrier sense target frequencies during execution of carrier sense. Receive radio waves.

When the presence of interference is detected at the frequency F1 in the carrier sense in the section t1, the control unit 201 of the transmission station determines whether or not there is interference at F4 in the carrier sense in the section. It judges that it is in a state and switches the use frequency so that the information transmitted in F1 is transmitted in F4.
In the example of FIG. 6, since an error packet is generated due to interference in the data transmission in the section t1 and the usage frequency F1, retransmission is performed in the data transmission in the section t2 and the usage frequency F4.

After the section t2, the frequency F1 is set as a backup radio channel, and F1 is always in a receiving state at the receiving station. In F1 of the backup radio channel, carrier sense request reception and carrier sense response transmission are not performed.
In the use frequencies F2 and F3, as a result of automatic retransmission control (ARQ) and carrier sense, there was no occurrence of error packets or interference, so data transmission (initial transmission) is executed for each section.

[Operation at Each Frequency in First Wireless Communication Device (2): FIG. 7]
Next, the operation state at each frequency in the transmitting station when interference occurs also in the backup radio channel will be described with reference to FIG. FIG. 7 is a schematic explanatory diagram illustrating an operation state at each frequency when interference occurs even in the standby radio channel in the first radio communication apparatus.
As shown in FIG. 7, in a section t1, a data block is transmitted at use frequencies F1, F2, and F3, and ARQ and carrier sense are executed. In F4, carrier sense is executed.
As a result, the transmitting station detects that interference has occurred in the frequencies F1 and F4. Further, it is assumed that an error packet has occurred in the transmission data of F1. In this case, since F4 cannot be used, it is determined that there is no free channel.

In this case, since the control unit 201 of the transmitting station cannot switch F1 to F4, the presence or absence of interference between F2 and F3 is determined, and if there is no interference, data to be transmitted at F1 Are transmitted to F2 and F3.
In the example of FIG. 7, the data block transmitted by F1 in the section t1 is retransmitted using the frequency F2 in the section t2. The data block that should have been transmitted next in F2 is transmitted in section t3.

  In this system, although the transmission efficiency is reduced by this control, the data block can be reliably transmitted without using the radio channel in which the interference has occurred, and the communication reliability of the entire system is improved. It is something that can be done.

[Effect of the first embodiment]
According to the wireless communication apparatus according to the first embodiment of the present invention, transmission data is divided and transmitted in parallel using a plurality of wireless channels, and every time data of one data block is transmitted. In addition to transmitting an instruction for performing carrier sense for a plurality of used radio channels and backup radio channels to each receiving station, the own station also performs carrier sense for the used radio channel and backup radio channel, and results of carrier sense of each station To determine whether there is interference between each of the used radio channels and the backup radio channel. If there is interference in any of the used radio channels and there is no interference in the backup radio channel, the used radio in which the interference has occurred. Since the use of the channel is stopped and the data transmitted on the stopped wireless channel is transmitted using the backup wireless channel, Can send data reliably without using a radio channel there is a risk of negotiations, to maintain communication, there is an effect that it is possible to improve the reliability of communication.

  Further, according to the first wireless communication apparatus, when there is interference in any of the used radio channels and there is also interference in the backup radio channel, the use of the used radio channel in which the interference has occurred is stopped and stopped. The data transmitted on the wireless channel is distributed to the used wireless channel where interference does not occur, and data can be transmitted reliably without using a wireless channel that may cause interference. There is an effect that communication can be maintained and communication reliability can be improved.

[Second Embodiment]
Next, a radio communication apparatus (second apparatus) according to the second embodiment of the present invention will be described.

[About frequency utilization efficiency]
Before describing the second device, frequency utilization efficiency in the wireless communication system will be described.
During carrier sense execution, the wireless communication device needs to stop transmission at the carrier sense target frequency and measure received power from another wireless communication system. Therefore, when carrier sense is periodically executed at a constant time interval, a time during which transmission cannot be performed periodically occurs, the transmission time for transmitting the entire data increases, and the frequency utilization efficiency decreases. Therefore, it is necessary to appropriately select the carrier sense execution interval and the execution time per time.
Furthermore, since the transmitting station stops the next data transmission when performing automatic retransmission, the automatic retransmission control time also causes a decrease in transmission efficiency.

Therefore, in the wireless communication apparatus (second wireless communication apparatus) according to the second embodiment, in order to reduce a decrease in frequency utilization efficiency due to application of automatic retransmission control (ARQ) and carrier sense, The frame format (error packet / carrier sense request channel) in which the carrier sense request channel is integrated and the frame format (error packet / carrier sense response channel) in which the error packet response channel and the carrier sense response channel are integrated are used. Thus, a sequence in which the transmission time and processing of the control channel are simplified is executed.
The configuration of the second wireless communication apparatus is the same as that of the first wireless communication apparatus shown in FIG. 1, but the automatic retransmission control and carrier sense control are different.

[Operation Sequence in Second Wireless Communication Device: FIG. 8]
Next, an operation sequence in the system using the second wireless communication apparatus will be described with reference to FIG. FIG. 8 is an explanatory diagram showing an operation sequence in the system using the second wireless communication apparatus (described as “operation sequence in the second embodiment” in the figure).
The sequence shown in FIG. 8 shows the operation at the frequency F1 similarly to the sequence shown in FIG. 4, and switches the use frequency from F1 to F4. Further, the sequence of FIG. 8 continues from (a), (b), (c), and (d) of FIG.
4 differs from the sequence shown in FIG. 4 in that automatic retransmission control sequences 316 to 322 and carrier sense sequences 324 to 331 in FIG. 4 are replaced with automatic retransmission control / carrier sense common sequences 340 to 347 in FIG. Only the automatic retransmission control / carrier sense common sequence 340 to 347 of FIG. 8 will be described here. About the operation | movement before and behind that, it is the same as the operation | movement sequence of FIG. 4, and description is abbreviate | omitted.

As shown in FIG. 8, in the system using the second wireless communication apparatus, the following automatic retransmission control / carrier sense operation sequences 340 to 347 are executed every time transmission of data packets for one data block is completed. The
The transmitting station transmits an error packet / carrier sense request channel to each receiving station in order to check whether the transmitted data packet can be accurately transmitted without transmission errors and whether interference has occurred in the use frequency. (340).

  After T3 'from completion of transmission / reception of the error packet / carrier sense request channel, carrier sense is executed in the transmitting station, receiving station 1, receiving station 2, and receiving station 3 (341). Here, T3 ′ is the time required for data processing for generating an error packet part in the error packet / carrier sense response channel at the receiving station.

As in the case of the carrier sense response and the error packet response shown in FIG. 4, after receiving the carrier sense, each receiving station switches to the transmission state and transmits the error packet / carrier sense response channel (however, the reception mode state is maintained). To do).
Each receiving station 1, 2 and 3 transmits the error packet / carrier sense response channel in a time division manner, and the receiving station 1 which responds first starts transmitting an error packet / carrier sense response T1 after completion of the carrier sense execution. (342). T1 is a time required for data processing for switching from reception to transmission state and generating a carrier sense response unit in an error packet / carrier sense response channel.

Thereafter, the receiving stations 2 and 3 transmit the error packet / carrier sense response channel at sequentially set timings. The time interval at this time is T5 (344, 346).
T5 is the time required for transmission of the error packet / carrier sense response, and absorbs the difference in delay time in the propagation path due to the difference in the location of each receiving station in addition to the data transmission time from the receiving station. Including the margin.

The transmitting station receives an error packet / carrier sense response channel from each receiving station (323, 345, 347), and detects the presence / absence of an error packet and the presence / absence of interference at each frequency.
As described above, in the system using the second wireless communication apparatus, the automatic retransmission control / carrier sense common sequence using the error packet / carrier sense request channel and the error packet / carrier sense response channel is performed.

[Frame Format Configuration Example (3): FIG. 9]
Next, a frame format configuration used in the second wireless communication apparatus will be described with reference to FIG. FIG. 9 is an explanatory diagram showing frame format configurations of an error packet / carrier sense request channel and an error packet / carrier sense response channel.
[Error packet / carrier sense request channel: FIG. 9 (a)]
The error packet / carrier sense solicitation channel is a control channel for instructing the transmitting station to detect and respond to an error packet, execute carrier sense, and respond to the result.
As shown in FIG. 9 (a), the error packet / carrier sense solicitation channel is the same as the channel shown in FIGS. 3 and 5, and the synchronization information and setting information (identification indicating error packet / carrier sense solicitation). (Symbol) includes the same information as the error packet request channel shown in FIG. 5F, and further includes the same information as the carrier sense request channel shown in FIG.

[Error packet / carrier sense response channel: FIG. 9B]
The error packet / carrier sense response channel is a control channel in which the receiving station notifies the transmitting station of error packet information and a carrier sense result in response to an error packet / carrier sense request.
As shown in FIG. 9 (b), the error packet / carrier sense response channel includes the same information as the error packet response channel shown in FIG. 5 (g) following the synchronization information and setting information. It contains the same information as the carrier sense response channel shown in b).
A sequence using an error packet / carrier sense request channel and an error packet / carrier sense response channel is set as an automatic retransmission control / carrier sense common sequence.

[Operation at Each Frequency in Second Wireless Communication Device: FIG. 10]
Next, the operation state for each radio channel in the system using the second radio communication apparatus that performs the automatic retransmission control / carrier sense common sequence will be described with reference to FIG. FIG. 10 is a schematic explanatory diagram illustrating an operation state for each wireless channel in the second wireless communication apparatus.
In the operation of the first wireless communication apparatus shown in FIGS. 6 and 7, ARQ and carrier sense are performed separately, whereas in the second wireless communication apparatus, as shown in FIG. The sense is integrated and executed. Thereby, the frequency utilization efficiency is improved.
In F4, which is a backup radio channel, since data transmission is not performed in the t1 interval, only carrier sense is performed instead of ARQ / carrier sense.

[About the frequency utilization efficiency in the second embodiment]
Next, frequency utilization efficiency when the automatic retransmission control (ARQ) / carrier sense common sequence is applied will be described.
The frequency utilization efficiency [bps / Hz] is obtained by dividing the throughput [bps] by the utilization frequency bandwidth [Hz]. Since the utilization frequency bandwidth is constant, the automatic retransmission request (ARQ) and carrier sense execution are performed. By comparing the overhead time (T_OH), the frequency utilization efficiencies of the first wireless communication device and the second wireless communication device can be compared.

In the first wireless communication apparatus, the overhead time T_OH required to execute automatic retransmission control and carrier sense once is as follows when the number of receiving stations is 3.
T_OH = (T1 + T2 x number of receiving stations) + (T3 + T4 x number of receiving stations) + Tcs
= (T1 + (T2t + Tm) x number of receiving stations) + (T3 + (T4t + Tm) x number of receiving stations) + Tcs
= T1 + T3 + (T2t + T4t + 2 x Tm) x 3 + Tcs (Equation 1)
Here, T1 is the time from the completion of carrier sense execution until the receiving station 1 starts transmitting a carrier sense response, and data for switching from reception to transmission state at the receiving station and for generating a carrier sense response channel This is the time required for processing.
T2 is the time required for transmission of the carrier sense response to absorb the difference in delay time in the propagation path due to the difference in the location of each receiving station in addition to the data transmission time (T2t) from the receiving station. The margin (Tm) is included.

T3 is the time from when the reception of the error packet request channel is completed until the receiving station 1 starts to transmit the error packet response, for switching from reception to transmission state at the receiving station and for generating the error packet response channel. This is the time required for data processing.
T4 is the time required to transmit the error packet response, and in order to absorb the difference in delay time in the propagation path due to the difference in the location of each receiving station in addition to the data transmission time (T4t) from the receiving station The margin (Tm) is included.
Tcs is the carrier sense execution time.

  Note that the transmission times of the error packet request channel and the carrier sense request channel are small and are ignored. From (Equation 1), in the case of the first wireless communication apparatus, the margin included in the overhead time (T_OH) is 6 Tm.

On the other hand, the overhead time T_OH required to execute automatic retransmission control and carrier sense once in the second wireless communication apparatus is as follows when the number of receiving stations = 3.
T_OH = T1 + T3 '+ T5 x number of receiving stations + Tcs
= T1 + T3 '+ (T5t + Tm) x number of receiving stations + Tcs
= T1 + T3 '+ (T5t + Tm) x 3 + Tcs (Formula 2)
T3 ′ is a time required for data processing for generating an error packet part in the error packet / carrier sense response channel in the receiving station.
T5 is the time required for transmission of the error packet / carrier sense response. In addition to the data transmission time (T5t) from the receiving station, the delay time in the propagation path due to the difference in the location of each receiving station Includes a margin (Tm) to absorb the difference.
Other values are the same as in the case of Equation 1.

  Since the transmission time of the error packet / carrier sense request channel is small, it is ignored. (Equation 2) shows that in the case of the second wireless communication apparatus, the included margin is 3 Tm, which is smaller than that of the first wireless communication apparatus.

Also, even if the channel formats are compared, the length of the error packet / carrier sense response channel used in the second radio communication device is the same as that of the error packet response channel and carrier sense response channel used in the first radio communication device. It is shorter than the length by the amount of synchronization information and setting information.
Further, T3 ′ in (Equation 2) is smaller than T3 in (Equation 1) because it does not include the transmission / reception switching time of the receiving station.
As described above, in the second embodiment to which the automatic retransmission control (ARQ) / carrier sense common sequence is applied, overhead due to automatic retransmission control and carrier sensing can be reduced, and reduction in transmission efficiency can be reduced. It can be done.

[Effect of the second embodiment]
According to the radio communication apparatus according to the second embodiment of the present invention, an automatic retransmission control / carrier sense request channel in which an automatic retransmission control (ARQ) request channel and a carrier sense request channel are integrated is used, and By using an automatic retransmission control / carrier sense response channel in which an automatic retransmission control (ARQ) response channel and a carrier sense response channel are integrated, automatic retransmission control (ARQ) and carrier sense are executed in a common sequence. Therefore, there is an effect that a reduction in transmission efficiency due to execution of automatic retransmission control or carrier sense can be reduced.

[Third Embodiment]
A wireless communication apparatus (third wireless communication apparatus) according to the third embodiment of the present invention will be described.
The third wireless communication apparatus further reduces the decrease in frequency utilization efficiency. When operating as a transmitting station, the error packet response from the receiving station indicates that there is an error in the received packet (that is, due to interference). Only when there is a possibility that an error has occurred), carrier sense is executed for the transmission of the next subsequent data block.
However, the carrier sense is always performed for the backup radio channel.
The configuration of the third wireless communication apparatus is the same as that of the first wireless communication apparatus shown in FIG. 1, but the automatic billing control and carrier sense control are different.

[Operation Sequence in Third Wireless Communication Device: FIG. 11]
Next, an operation sequence in the system using the third wireless communication apparatus will be described with reference to FIG. FIG. 11 is an explanatory diagram illustrating an operation sequence (an operation sequence according to the third embodiment in the figure) in a system using the third wireless communication apparatus.
The operation sequence shown in FIG. 11 shows the operation in F1, and is continued from (a), (b), (c), and (d) in FIG. 2, as in FIGS. is there.

In the sequence using the third wireless communication apparatus, the automatic retransmission control and carrier sense sequences are different from those in FIGS. Since the sequence other than the automatic retransmission control and the carrier sense sequence is the same as that in FIG.
As shown in FIG. 11, when transmission of data packets for one data block (315) is completed, the transmitting station transmits an error packet request channel to each of the receiving stations 1, 2, 3 (360).
Each receiving station transmits an error packet response channel to the transmitting station (361, 363, 365), and the transmitting station receives them (362, 364, 366). The transmission / reception timing of the error packet response is the same as in FIG.

From here, the case where the received error packet response indicates no error and the case where there is an error will be described separately.
When the error packet response indicates no error packet (367), the transmitting station transmits a data channel for the next one data block (368), and transmits an error packet request channel (369). As a feature of the third wireless communication apparatus, when there is no error packet, carrier sense is not executed, and data channel transmission, error packet solicitation channel transmission, and error packet response channel reception are repeated (362 to 366).

Also, when an error packet response is received from the receiving station (371, 373, 375) and the received error packet response indicates that there is an error packet (367), the transmitting station transmits a retransmission data channel. (377).
Since there was an error packet, there is a possibility that interference has occurred at the frequency F1, and the transmitting station performs carrier sense for each frequency. That is, the transmitting station transmits an error packet / carrier sense request channel to each receiving station by F1, F2, and F3 (378), and carrier sense execution (379) is performed by F1, F2, F3, and F4. Transmission / reception 380 to 385 of the error packet / carrier sense response channel is executed in F2 and F3.
The carrier sense instruction for F4 and its result are also indicated by the error packet / carrier sense request channel and are returned by the error packet / carrier sense response channel.

The control unit 201 of the transmitting station totals the carrier sense results from the own station and each receiving station, and determines whether there is interference for the frequencies F1, F2, F3, and F4. If it is determined that interference has occurred in the frequency F1, if there is no interference in F4 of the backup radio channel, a use frequency channel setting (setting change) for switching the use frequency from F1 to F4 is transmitted (390). ), The data transmitted in F1 is transmitted using F4.
If interference occurs at F4 and no interference occurs at F2 and F3, data to be transmitted at F1 is distributed to F2 and F3 for transmission.
In this way, a sequence using the third wireless communication apparatus is performed.

[Operation at Each Frequency in Third Wireless Communication Device: FIG. 12]
Next, the operation state for each wireless channel in the system using the third wireless communication apparatus will be described with reference to FIG. FIG. 12 is a schematic explanatory diagram illustrating an operation state for each wireless channel in the third wireless communication apparatus.
As shown in FIG. 12, in the third wireless communication apparatus, when data transmission is performed using the usage frequencies F1, F2, and F3 in the section t1, only ARQ is performed immediately after that, and carrier sense is not performed.

  If there is no error packet at all frequencies as a result of ARQ in section t1, carrier sense is not performed in section t2. That is, when the next data packet is transmitted, only ARQ is performed and carrier sense is not performed.

If there is an error packet at any frequency, not only ARQ but also carrier sense is performed in the next section.
In the example of FIG. 12, an error packet is detected at the frequency F1 in the ARQ in the interval t2, and in the interval t3, ARQ / carrier sense is performed at all the used frequencies after the next data packet transmission.
In the example of FIG. 12, the use frequency is switched from F1 to F4 where interference has occurred, and data in which an error packet has occurred is retransmitted using the frequency F4 in a section t4.

As described above, in the third wireless communication apparatus, if there is no error packet in the received data, it is possible to further reduce the overhead time due to carrier sense by not transmitting / receiving the control channel associated with carrier sense. Is.
Here, once there is an erroneous packet, carrier sense is performed in addition to ARQ thereafter. However, when “no error” is detected for a predetermined number of times after detecting “packet present”. May perform ARQ only again. Thereby, the overhead time can be further reduced.

[Effect of the third embodiment]
According to the wireless communication apparatus of the third embodiment of the present invention, after transmitting the data block, the carrier sense request is not transmitted, only the error packet request is transmitted, and the error packet response from the receiving station is “error”. When there is a packet, the carrier sense request is transmitted after the next data block transmission. Therefore, when there is no error packet in the received data at the receiving station and there is no interference in the used radio channel. Does not perform carrier sense, and if there is an error packet, carrier sense is performed to confirm the presence of interference, and if there is interference, the frequency used is changed, thus ensuring communication reliability. On the other hand, there is an effect that the overhead time due to carrier sense can be shortened and the decrease in frequency utilization efficiency can be reduced.

  The present invention is suitable for a wireless communication apparatus that can maintain communication while avoiding interference with other communication systems, and improve communication reliability.

  DESCRIPTION OF SYMBOLS 100 ... Transmitting station 101, 102, 103 ... Receiving station 104 ... Spectrum management server 105 ... Communication group 106 ... Other radio | wireless communications system 200 ... Transmission / reception processing part 201 ... Control part 202 ... Dividing / assembling means, 203 ... Frame processing means, 204 ... Data transmission means, 205 ... Error correction means, 206 ... Modulation / demodulation means, 207 ... Radio unit, 208 ... Error detection means, 209 ... Automatic retransmission control means

Claims (1)

A wireless communication device that divides transmission data and transmits to a plurality of receiving stations in parallel using a plurality of frequencies,
A carrier sense unit for performing carrier sense to detect the power level of the received signal;
Each time data of a predetermined transmission unit is transmitted, the carrier sense unit outputs an instruction to perform carrier sense for a plurality of use frequencies used for transmission and reception and a spare frequency set as a spare, and An instruction to perform carrier sense on the plurality of used frequencies and the backup frequency is transmitted to the receiving station,
Based on the result of carrier sense in the carrier sense unit and the result of carrier sense received from the receiving station, determine the presence or absence of interference for the plurality of used frequencies and the backup frequency,
As a result of the determination, if there is interference in any of the plurality of used frequencies and there is no interference in the backup frequency, use of the used frequency in which the interference has occurred is stopped, and transmission is performed at the stopped frequency. Data transmitted at the spare frequency,
As a result of the determination, when there is interference between any of the plurality of used frequencies and the backup frequency, the use of the used frequency in which the interference has occurred is stopped, and the data transmitted at the stopped frequency is And a control unit that distributes and transmits to a use frequency other than the stopped frequency.

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