JP6917682B2 - Communication device and communication control method - Google Patents

Description

The present disclosure relates to communication devices and communication control methods.

In recent years, a wireless sensor network for collecting information by wireless communication from a terminal having a sensor function has attracted attention. The wireless sensor network has a wide range of uses, such as confirming the position of the target of interest and managing the behavior of the target of interest.

In existing cellular systems and wireless communication systems such as wireless LAN (Local Area Network), a master station such as a base station or an access point manages communication resources. For example, the master station periodically transmits a reference signal, determines the communication resource for the communication terminal on the slave station side, notifies the determined communication resource to the communication terminal according to a predetermined control protocol, and the communication terminal receives the determined communication resource. Communication is performed using the reception result of the reference signal and the notified communication resource. With this management, it is possible to avoid or suppress interference between communications performed by a plurality of communication terminals. Regarding the above wireless communication system, Patent Document 1 discloses a technique for controlling whether or not to continue reception processing based on the frequency offset of the received preamble.

Japanese Unexamined Patent Publication No. 2000-4177

In the wireless communication system described above, it is possible to reduce the cost of the terminal by designing the hardware of the communication terminal so that the maximum available transmission power is limited. However, when the transmission power is limited, the communicable distance is also limited. In this regard, as a technique for performing long-distance transmission by a communication terminal with low transmission power, for example, there is H-ARQ (Hybrid-ARQ) adopted in cellular communication. H-ARQ is a technique for improving reception sensitivity by repeatedly transmitting the same frame on the transmitting side and synthesizing a plurality of frames by signal processing on the receiving side.

When applying H-ARQ to a multi-access environment where multiple communication terminals can exist, it is possible to synthesize reception signals from the same communication terminal by identifying the transmission terminal of each reception signal before synthesis. Become. As described above, if communication for managing communication resources is performed in advance, it is easy to identify the transmitting terminal of each received signal.

However, communication for managing communication resources, that is, reception of the above-mentioned reference signal and communication according to a predetermined control protocol, consumes the power of the communication terminal.

Therefore, the present disclosure proposes a new and improved communication device and communication control method capable of reducing power consumption for managing communication resources in a system in which a plurality of received signals are synthesized.

According to the present disclosure, an evaluation unit that evaluates the carrier frequency of a received signal received from another communication device, and two or more received signals are extracted from a plurality of received signals based on the evaluation results by the evaluation unit. A communication device is provided that includes a synthesis processing unit that performs synthesis processing of the two or more received signals.

Further, according to the present disclosure, the processor evaluates the carrier frequency of the received signal received from another communication device, and two or more received signals are extracted from the plurality of received signals based on the evaluation result. , The communication control method including the synthesis processing of the two or more received signals is provided.

As described above, according to the present disclosure, it is possible to reduce the power consumption for managing communication resources in a system in which a plurality of received signals are synthesized.

It should be noted that the above effects are not necessarily limited, and either in combination with or in place of the above effects, any of the effects shown herein, or any other effect that can be grasped from this specification. May be played.

It is explanatory drawing which shows the structure of the wireless communication system by embodiment of this disclosure. It is explanatory drawing which shows an example of the division of the communication resource on the time axis. It is explanatory drawing which shows the structural example of the frame transmitted by the sensor terminal. It is explanatory drawing which shows the structure of the sensor terminal by embodiment of this disclosure. It is explanatory drawing which shows the structure of the base station by embodiment of this disclosure. It is explanatory drawing which shows the structure of the evaluation part. It is a flowchart which shows the operation of the sensor terminal by embodiment of this disclosure. It is a flowchart which shows the operation of the base station by embodiment of this disclosure. It is explanatory drawing which shows the generation of a GOLD sequence. It is explanatory drawing which shows the structure of the evaluation part by 1st application example. It is a flowchart which shows the operation of the sensor terminal by 1st application example. It is a flowchart which shows the operation of the base station by 1st application example. It is a flowchart which shows the operation of the sensor terminal by the 2nd application example. It is explanatory drawing which shows the specific example of a hopping pattern. It is explanatory drawing which shows the specific example of a hopping pattern. It is explanatory drawing which shows the specific example of a hopping pattern. It is explanatory drawing which shows an example of the reception result by a base station. It is explanatory drawing which shows another example of the reception result by a base station. It is a flowchart which shows the operation of the sensor terminal by the 3rd application example. It is a flowchart which shows the operation of the base station by the 3rd application example. It is explanatory drawing which showed the hardware configuration of a sensor terminal.

Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. In the present specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals, so that duplicate description will be omitted.

Further, in the present specification and the drawings, a plurality of components having substantially the same functional configuration may be distinguished by adding different alphabets after the same reference numerals. For example, a plurality of configurations having substantially the same functional configuration or logical significance are distinguished as necessary, such as sensor terminals 20A, 20B, and 20C. However, if it is not necessary to distinguish each of the plurality of components having substantially the same functional configuration, only the same reference numerals are given. For example, when it is not necessary to distinguish between the sensor terminals 20A, 20B and 20C, the sensor terminals 20A, 20B and 20C are simply referred to as the sensor terminals 20.

In addition, the present disclosure will be described according to the order of items shown below.
1. 1. Overview of wireless communication system 2. Configuration of sensor terminal 3. Base station configuration 4. Operation 5. Application example 5-1. First application example 5-2. Second application example 5-3. Third application example 6. Hardware configuration 7. Conclusion

<< 1. Overview of wireless communication system >>
Embodiments of the present disclosure relate to wireless communication systems that form wireless sensor networks. First, the outline of the wireless communication system according to the embodiment of the present disclosure will be described with reference to FIG.

(1-1. Configuration of wireless communication system)
FIG. 1 is an explanatory diagram showing a configuration of a wireless communication system according to the embodiment of the present disclosure. As shown in FIG. 1, the wireless communication system according to the embodiment of the present disclosure includes a plurality of base stations 10, a plurality of sensor terminals 20, and an application server 30.

The base station 10 is a communication device having a function of performing wireless communication with the sensor terminal 20 and a function of performing wired communication with the application server 30. For example, the base station 10 wirelessly communicates with the sensor terminal 20 located in the cell. In the example shown in FIG. 1, the base station 10A wirelessly communicates with the sensor terminals 20A, 20B and 20C located in the cell of the base station 10A, and the base station 10B is a sensor located in the cell of the base station 10B. Wireless communication is performed with terminals 20D, 20E, 20F and 20G. In particular, the base station 10 according to the present embodiment receives the sensor data from the sensor terminal 20 and transmits the sensor data to the application server 30.

The sensor terminal 20 has a sensor function and a function of performing wireless communication with the base station 10. For example, the sensor function can be realized by various sensors such as an acceleration sensor, a gyro sensor, a temperature sensor, a pressure sensor, a sound pressure sensor, a pulse sensor or a GPS (Global Positioning System). The sensor terminal 20 transmits the sensor data acquired by the sensor function to the base station 10.

The application server 30 receives the sensor data obtained by the sensor terminal 20 from the base station 10 and provides a service using the received sensor data. There are a wide variety of services that use sensor data, such as a service that confirms the position of an object of interest and a service that manages the behavior of the object of interest. Regarding the service for confirming the position of the object of interest, for example, an elderly person or a child wears a sensor terminal 20 having a GPS function, and an application server 30 acquires position information from the sensor terminal 20 via a base station 10. This makes it possible to provide the family and government with the location of the elderly and children. Regarding the service for managing the behavior of the object of interest, for example, a sensor terminal 20 having an acceleration sensor is attached to livestock such as cows and pigs, and an application server 30 provides information on the movement of livestock from the sensor terminal 20 via the base station 10. It is possible to manage the behavior of livestock in the pasture by acquiring.

In this embodiment, the sensor terminal 20 having a sensor function will be described as an example of the communication device, but the present embodiment can also be applied to a communication device having no sensor function. For example, the communication device may be supplied with data from an external device and transmit the supplied data to the base station 10. When the external device is a vending machine, the communication device may be supplied with sales data from the vending machine and transmit the sales data to the base station 10.

(1-2. Overview of wireless communication)
The configuration of the wireless communication system according to the embodiment of the present disclosure has been described above. Subsequently, an outline of wireless communication between the base station 10 and the sensor terminal 20 in the wireless communication system will be described.

-Communication resource The base station 10 and the sensor terminal 20 share the start timing of each communication resource divided on the time axis. The sharing can be realized, for example, by the base station 10 transmitting a reference signal for time synchronization and the sensor terminal 20 receiving the reference signal. However, if the sensor terminal 20 continuously receives the reference signal, a corresponding amount of power is consumed. Therefore, the base station 10 and the sensor terminal 20 may share the start timing of each communication resource based on the absolute time managed by each. The sensor terminal 20 can acquire the absolute time, for example, by GPS reception processing. Hereinafter, an example of communication resources on the time axis whose timing is shared by the base station 10 and the sensor terminal 20 will be described with reference to FIG.

FIG. 2 is an explanatory diagram showing an example of division of communication resources on the time axis. In the present embodiment, the communication resource on the time axis is divided into resource units called superframes. In the example shown in FIG. 2, 10 superframes including superframes # 0 to # 9 are repeated. The time width of each super frame is not particularly limited, and may be, for example, 6 seconds. If the time width of each superframe is 6 seconds, the cycle of repeating the superframe is 1 minute. The sensor terminal 20 uses one of the super frames to transmit a frame including sensor data.

-Frame configuration FIG. 3 is an explanatory diagram showing a configuration example of a frame transmitted by the sensor terminal 20. As shown in FIG. 3, the frames transmitted by the sensor terminal 20 include a preamble 51, an SFD (Sync Frame Detector) 52, a terminal ID 53, data 54, a CRC (Cyclic Redundancy Check) 55, and a parity bit 56. And, including.

The preamble 51 is a signal pattern used in the base station 10 for detecting a frame. The SFD 52 is a signal pattern indicating the start position of the payload (terminal ID 53 to parity bit 56) in the frame. By detecting the SFD 52 from the frame in which the preamble 51 is detected, the base station 10 recognizes that the subsequent parts are the payload.

The terminal ID 53 is an ID of the sensor terminal 20 that transmits a frame. The terminal ID 53 may be, for example, a unique number of the sensor terminal 20. The data 54 is data for use in the application server 30, and sensor data such as acceleration information and position information may be included in the data 54. The CRC55 is used to determine whether or not the frame has been successfully received. The parity bit 56 is a redundant bit generated according to the terminal ID 53, the data 54, and the CRC 55, and the use of the parity bit improves the reception success rate of the frame at the base station 10.

-Long-distance transmission In order to realize a wireless communication system at a lower cost, it is effective to widen the cell area covered by one base station 10, that is, long-distance transmission. In long-distance transmission, it is possible to reduce the number of base stations 10 constituting the wireless communication system.

It is also possible to reduce the cost of the sensor terminal 20 by designing the hardware of the sensor terminal 20 so that the maximum available transmission power is limited. However, when the transmission power is limited, the communicable distance is also limited. In this regard, as a technique for the sensor terminal 20 to perform long-distance transmission with low transmission power, for example, there is H-ARQ (Hybrid-ARQ) adopted in cellular communication. H-ARQ is a technique for improving reception sensitivity by repeatedly transmitting the same frame on the transmitting side and synthesizing a plurality of frames by signal processing on the receiving side.

Specifically, the sensor terminal 20 according to the H-ARQ receives the frame described with reference to FIG. 3 until the reception confirmation (ACK) is received from the base station 10 or until the number of transmissions reaches the upper limit. Send repeatedly. The base station 10 synthesizes frames each time a new frame is received, and transmits ACK to the sensor terminal 20 when demodulation is successful.

(1-3. Background)
When applying the above-mentioned H-ARQ to a multi-access environment in which multiple communication terminals can exist, it is possible to synthesize frames from the same communication terminal by identifying the transmitting terminal of each frame before synthesizing. Become. In wireless communication systems such as cellular systems and wireless LANs, a master station such as a base station or an access point communicates with a communication terminal for management of communication resources. If communication for managing such communication resources is performed in advance, it is easy to identify the transmitting terminal of each frame.

However, since the communication for managing the communication resource includes, for example, the reception of a reference signal at the communication terminal and the communication according to a predetermined control protocol, the power of the communication terminal is consumed. In particular, it is assumed that the data transmitted by the sensor terminal belonging to the sensor network is a small amount of data of about several bytes, and in this case, the power consumed for managing communication resources is consumed for data transmission. The ratio to the electric power will increase.

Therefore, the inventor of the present invention has come to create the embodiment of the present disclosure by paying attention to the above circumstances. According to the embodiment of the present disclosure, it is possible to reduce the power consumption for managing communication resources in a system in which a plurality of frames are synthesized. Hereinafter, the configuration and operation of such an embodiment of the present disclosure will be sequentially described in detail.

<< 2. Sensor terminal configuration >>
FIG. 4 is an explanatory diagram showing the configuration of the sensor terminal 20 according to the embodiment of the present disclosure. As shown in FIG. 4, the sensor terminal 20 according to the embodiment of the present disclosure includes a wireless communication unit 220, a sensor unit 230, a carrier wave generation unit 240, and a control unit 250.

(Wireless communication unit)
The radio communication unit 220 performs reception processing of the radio signal transmitted from the base station 10 and transmission processing of the radio signal to the base station 10. More specifically, the wireless communication unit 220 converts a wireless signal transmitted from the base station 10 (for example, a wireless signal in the 920 MHz band) into a high-frequency reception signal by an antenna, and analog-processes and downloads the high-frequency reception signal. By performing conversion, the base band reception signal is output. Further, the wireless communication unit 220 up-converts the baseband transmission signal supplied from the control unit 250 into a high-frequency transmission signal in the carrier frequency band, and converts the high-frequency transmission signal obtained by the up-conversion into a wireless signal by an antenna. Send. The up-conversion to the high-frequency transmission signal and the down-conversion to the baseband reception signal are performed using the carrier wave generated by the carrier wave generation unit 240.

(Sensor part)
The sensor unit 230 includes one or more sensors. In FIG. 4, the GPS processing unit 232 is shown as an example of the sensor. The GPS processing unit 232 acquires the position information and the time information of the sensor terminal 20 by processing the satellite signal transmitted from the GPS satellite. The sensor unit 230 may have other sensors such as an accelerometer, a gyro sensor, a temperature sensor, a barometric pressure sensor, a sound pressure sensor and a pulse sensor in addition to or in place of the GPS processing unit 232. good.

(Carrier generator)
The carrier wave generation unit 240 generates a carrier wave used for up-conversion from a baseband transmission signal to a high-frequency transmission signal and down-conversion from a high-frequency reception signal to a baseband reception signal. The carrier wave generation unit 240 generates a carrier wave by adjusting the frequency of a reference signal generated by an oscillator such as a crystal oscillator.

(Control unit)
The control unit 250 controls the overall communication in the sensor terminal 20. For example, the control unit 250 generates a frame including the sensor data obtained by the sensor unit 230, and causes the wireless communication unit 220 to repeatedly transmit the frame. The control unit 250 stops the transmission of the frame when the ACK is received from the base station 10 or when the number of repeated transmissions reaches the upper limit.

<< 3. Base station configuration >>
The configuration of the sensor terminal 20 according to the embodiment of the present disclosure has been described above. Subsequently, the configuration of the base station 10 according to the embodiment of the present disclosure will be described with reference to FIG.

FIG. 5 is an explanatory diagram showing the configuration of the base station 10 according to the embodiment of the present disclosure. As shown in FIG. 5, the base station 10 according to the embodiment of the present disclosure includes a periodic signal generation unit 110, a wireless communication unit 120, an evaluation unit 130, a demodulation unit 140, a control unit 150, and a wired communication unit. 160 and.

(Periodic signal generator)
The periodic signal generation unit 110 generates a periodic signal used for up-conversion from the baseband transmission signal to the high-frequency transmission signal and down-conversion from the high-frequency reception signal to the baseband reception signal in the wireless communication unit 120. The periodic signal generation unit 110 generates the periodic signal by adjusting the frequency of the reference signal generated by an oscillator such as a crystal oscillator.

(Wireless communication unit)
The wireless communication unit 120 performs reception processing of the wireless signal transmitted from the sensor terminal 20 and transmission processing of the wireless signal to the sensor terminal 20. More specifically, the wireless communication unit 120 converts the wireless signal transmitted from the sensor terminal 20 into a high-frequency reception signal by an antenna, and performs analog processing and down-conversion on the high-frequency reception signal to receive baseband. Output a signal. Further, the wireless communication unit 120 up-converts the baseband transmission signal supplied from the control unit 150 into a high-frequency transmission signal in the carrier frequency band, and converts the high-frequency transmission signal obtained by the up-conversion into a wireless signal by an antenna. Send. The up-conversion to the high-frequency transmission signal and the down-conversion to the baseband reception signal are performed using the periodic signal generated by the periodic signal generation unit 110.

(Evaluation department)
The evaluation unit 130 evaluates the carrier wave of the received signal received from the sensor terminal 20. Specifically, the evaluation unit 130 detects a frequency error between the carrier wave of the received signal received from the sensor terminal 20 and the periodic signal generated by the periodic signal generation unit 110. Hereinafter, the configuration of the evaluation unit 130 will be described in more detail with reference to FIG.

FIG. 6 is an explanatory diagram showing the configuration of the evaluation unit 130. As shown in FIG. 6, the evaluation unit 130 has a plurality of correlation detection units 132 and a comparison unit 138.

Baseband reception signals are input from the wireless communication unit 120 to the plurality of correlation detection units 132. Each correlation detection unit 132 makes different adjustments regarding the frequency of the input baseband reception signal, and detects the correlation between the preamble included in the adjusted baseband reception signal and a predetermined comparison pattern.

Specifically, each correlation detection unit 132 has a plurality of phase adjusters r, a plurality of delay devices d, a plurality of multipliers m, an addition unit 134, and a correlation output unit 136. As shown in FIG. 6, the phase adjuster r and the delay device d are alternately arranged in series, and the multiplier m is arranged between the phase adjuster r and the delay device d.

The phase adjuster r has a function of rotating the phase of the signal. Here, the amount by which each phase adjuster r rotates the phase differs depending on which correlation detection unit 132 includes the phase adjuster r. That is, each correlation detection unit 132 has a function of shifting the frequency of the baseband reception signal, and the amount of the frequency shifted by each correlation detection unit 132 is different.

The output from each phase adjuster r and the element signal of the comparison pattern corresponding to the preamble used by the sensor terminal 20 are input to each multiplier m, and each multiplier m is input from each phase adjuster r. Multiply the output by the conjugate of the element signal of the comparison pattern.

The addition unit 134 adds the result of multiplication input from each multiplier m. The correlation output unit 136 converts the complex signal obtained by the addition unit 134 into a power signal, and outputs the power signal as a correlation value.

Here, the frequency of the carrier wave generated by the carrier wave generation unit 240 of the sensor terminal 20 and the frequency of the periodic signal generated by the periodic signal generation unit 110 of the base station 10 are different in quantity due to individual differences of the oscillator ( Hereinafter referred to as frequency error) may occur. Then, among the plurality of correlation detection units 132, the correlation detection unit 132 in which the frequency shift amount is the same as the frequency error outputs the maximum correlation value.

Therefore, the comparison unit 138 compares the correlation value output from each correlation detection unit 132 with the threshold value, and detects the amount of frequency shift by the correlation detection unit 132 that outputs the correlation value exceeding the threshold value as a frequency error. Since the frequency error may differ depending on the sensor terminal 20 of the transmission source, it is possible to identify the sensor terminal 20 of the transmission source of each received signal based on the frequency error.

(Demodulation unit)
The demodulation unit 140 extracts two or more received signals that are presumed to have the same source sensor terminal 20 based on the evaluation result by the evaluation unit 130, and performs a synthesis process of the extracted two or more received signals. It has the function of a synthesis processing unit to perform. Specifically, the demodulation unit 140 sequentially extracts the received signals in which the same frequency error is detected by the evaluation unit 130, and cumulatively synthesizes the payload of the extracted received signals. Then, the demodulation unit 140 attempts to demodulate the payload after synthesis. Whether or not the demodulation is successful is confirmed by using the CRC55 included in the payload described with reference to FIG.

The control unit 150 controls the overall communication of the base station 10. For example, the control unit 150 controls the wireless communication unit 120 so that when the demodulation unit 140 succeeds in demodulating the payload, ACK is transmitted as reception confirmation to the sensor terminal 20 that is the source of the payload.

The wired communication unit 160 is an interface with the application server 30. The wired communication unit 160 transmits the terminal ID and data included in the payload demodulated by the demodulation unit 140 to the application server 30.

<< 4. Operation >>
The configuration of the base station 10 and the sensor terminal 20 according to the embodiment of the present disclosure has been described above. Subsequently, with reference to FIGS. 7 and 8, the operations of the base station 10 and the sensor terminal 20 according to the embodiment of the present disclosure will be arranged.

(Operation of sensor terminal)
FIG. 7 is a flowchart showing the operation of the sensor terminal 20 according to the embodiment of the present disclosure. As shown in FIG. 7, first, the control unit 250 of the sensor terminal 20 generates the frame described with reference to FIG. 3 (S410), and the wireless communication unit 220 transmits the frame as a wireless signal (S420). .. After that, the control unit 250 waits for the reception of the ACK (S430 / NO, S450 / NO) until a timeout, that is, until a predetermined waiting time elapses, and ends the transmission operation when the ACK is received (S450 / NO). YES).

On the other hand, when a predetermined waiting time elapses without receiving ACK (S430 / YES), the control unit 250 determines whether or not the number of times of frame transmission has reached the upper limit (S440). When the number of times of frame transmission has not reached the upper limit (S440 / NO), the process from S410 is repeated, and when the number of times of frame transmission has reached the upper limit (S440 / YES), the transmission operation ends.

(Operation of base station)
FIG. 8 is a flowchart showing the operation of the base station 10 according to the embodiment of the present disclosure. When the radio communication unit 120 of the base station 10 receives the radio signal and outputs the baseband reception signal to the evaluation unit 130, the evaluation unit 130 calculates a frequency error based on the correlation detection process using the plurality of correlation detection units 132. Detect (S504).

Then, the demodulation unit 140 stores the payload cut out from the baseband reception signal when there is a payload stored in association with the frequency error detected by the evaluation unit 130 (S508 / YES). The payload is synthesized (S512). Then, the demodulation unit 140 performs demodulation processing of the synthesized payload (S516). On the other hand, when there is no payload stored in association with the frequency error detected by the evaluation unit 130 (S508 / NO), the demodulation unit 140 demodulates the payload cut out from the baseband reception signal. (S516).

When demodulation fails in S516 (S520 / NO), the demodulation unit 140 stores the payload targeted for demodulation processing in association with the frequency error detected in S504 (S524). On the other hand, when demodulation is successful in S516 (S520 / YES), the control unit 150 confirms the terminal ID included in the payload, and causes the wireless communication unit 120 to transmit ACK to the sensor terminal 20 that is the source of the wireless signal. (S528), the demodulation unit 140 deletes the payload stored in association with the frequency error detected in S504 (S532).

It is also possible that a plurality of frequency errors are detected in S504. When a plurality of frequency errors are detected in S504, the processes of S508 to S532 are executed for each frequency error.

As described above, according to the embodiment of the present disclosure, the base station 10 is based on the frequency error of the carrier wave of each received signal without prior communication with the sensor terminal 20 for managing communication resources. It is possible to identify the sensor terminal 20 that is the source of each received signal. Therefore, it is possible to reduce the power consumption for managing communication resources.

<< 5. Application example >>
As described above, the frequency error of the carrier wave of the received signal received from the plurality of sensor terminals 20 may differ due to the individual difference of the oscillators of each sensor terminal 20. However, there may be cases where the carrier frequency errors of the received signals received from different sensor terminals 20 are the same. In this case, it is difficult to identify the sensor terminal 20 that is the source of the received signal only from the frequency error. Therefore, some application examples capable of further improving the discriminating power of the transmission source will be described below. In addition, each application example described below may be applied individually to the above-described embodiment, or may be applied in combination.

<5-1. First application example>
First, as a first application example, a mechanism for identifying the source sensor terminal 20 from the preamble pattern in addition to the frequency error will be described.

(Constitution)
The control unit 250 of the sensor terminal 20 according to the first application example determines a preamble pattern used for frame transmission. Specifically, the control unit 250 determines the preamble pattern using the terminal ID of the sensor terminal 20. For example, in the GOLD sequence generation method for obtaining an output by combining different M sequences shown in FIG. 9, the control unit 250 uses at least a part of the terminal ID as one M sequence and preambles the obtained GOLD sequence. May be determined as.

If the control unit 250 determines the preamble pattern using the entire terminal ID, the sensor terminal 20 can be uniquely identified from the preamble pattern. However, it is assumed that the terminal ID is represented by 24 bits or 32 bits. In this case, the length of the preamble determined by using the entire terminal ID becomes 2 to the 24th power or 2 to the 32nd power. A long preamble is not preferable from the viewpoint of low power consumption.

In this regard, in the first application example, since the frequency error is also used for identifying the sensor terminal 20, the sensor terminal 20 can also be determined by using a part of the terminal ID as described above to determine the preamble pattern. It is possible to improve the discriminating power of. For example, the control unit 250 may generate a GOLD sequence using the lower 12 bits of the terminal ID and determine the GOLD sequence as a preamble pattern.

As described above, in the first application example, various patterns of preambles can be transmitted from the sensor terminal 20, so that the base station 10 performs correlation detection processing for each pattern of preambles that may be transmitted from the sensor terminal 20. conduct. This point will be described more specifically with reference to FIG.

FIG. 10 is an explanatory diagram showing the configuration of the evaluation unit 130 according to the first application example. As shown in FIG. 10, the evaluation unit 130 according to the first application example has a plurality of sets S1 and S2 of the correlation detection unit 132, and each set S has a plurality of correlation detection units 132. The same comparison pattern C is applied to the correlation detection unit 132 included in the same set S, and the comparison pattern C applied to each set S is different. For example, the comparison pattern C1 is applied to the set S1 shown in FIG. 10, and the comparison pattern C2 is applied to the set S2. Further, as described with reference to FIG. 6, the amount of frequency of the baseband received signal shifted by each correlation detection unit 132 included in the same set S is different. Although FIG. 10 shows two sets S1 and S2, the evaluation unit 130 may have more sets S.

In the above configuration, the maximum correlation value is output by the correlation detection unit 132 in which the frequency shift amount is the same as the frequency error and the comparison pattern corresponding to the preamble transmitted from the sensor terminal 20 is applied. ..

Therefore, the comparison unit 138 compares the correlation value output from each correlation detection unit 132 with the threshold value, detects the frequency shift amount by the correlation detection unit 132 that outputs the correlation value exceeding the threshold value as a frequency error, and also , The comparison pattern applied to the correlation detection unit 132 is detected as a transmitted preamble. The detected frequency error and preamble are used to identify the sensor terminal 20.

The demodulation unit 140 sequentially extracts the received signals in which the same frequency error and preamble are detected by the evaluation unit 130, and cumulatively synthesizes the payload of the extracted received signals. Then, the demodulation unit 140 attempts to demodulate the payload after synthesis.

(motion)
The configuration of the first application example has been described above. Subsequently, the operation of the first application example will be organized with reference to FIGS. 11 and 12.

FIG. 11 is a flowchart showing the operation of the sensor terminal 20 according to the first application example. As shown in FIG. 11, first, the control unit 250 of the sensor terminal 20 determines the preamble pattern using a part of the terminal ID (S402). Then, the control unit 250 generates a frame having a preamble of the determined pattern (S412), and the radio communication unit 220 transmits the frame as a radio signal (S422). Since the subsequent operations are as described with reference to FIG. 7, detailed description thereof will be omitted.

FIG. 12 is a flowchart showing the operation of the base station 10 according to the first application example. When the radio communication unit 120 of the base station 10 receives the radio signal and outputs the baseband reception signal to the evaluation unit 130, the evaluation unit 130 is based on the correlation detection process using the plurality of sets S of the correlation detection unit 132. Detect frequency errors and preambles (S506).

Then, the demodulation unit 140 stores the payload cut out from the baseband reception signal when there is a payload stored in association with the frequency error and the preamble detected by the evaluation unit 130 (S510 / YES). The payload is synthesized (S514). Then, the demodulation unit 140 performs demodulation processing of the synthesized payload (S518). On the other hand, when there is no payload stored in association with the frequency error detected by the evaluation unit 130 and the preamble (S510 / NO), the demodulation unit 140 demodulates the payload cut out from the baseband reception signal. (S518).

When demodulation fails in S518 (S522 / NO), the demodulation unit 140 stores the payload targeted for demodulation processing in association with the frequency error and preamble detected in S506 (S526). On the other hand, when the demodulation is successful in S518 (S522 / YES), the control unit 150 confirms the terminal ID included in the payload, and causes the wireless communication unit 120 to transmit the ACK to the sensor terminal 20 that is the source of the wireless signal. (S530), the demodulator 140 deletes the payload stored in association with the frequency error and preamble detected in S506 (S534).

As described above, according to the first application example, the received signal from the same sensor terminal 20 can be identified by using the preamble pattern in addition to the frequency error. Therefore, it is possible to identify the received signal from the same sensor terminal 20 with higher accuracy than when only the frequency error is used for identification.

<5-2. Second application example>
Next, as a second application example, a mechanism for identifying the source sensor terminal 20 from the super frame to which the frame is transmitted will be described in addition to the frequency error.

(Constitution)
The control unit 250 of the sensor terminal 20 according to the second application example determines a super frame for transmitting the frame. For example, the control unit 250 divides the terminal ID by the number of super frames for one cycle (10 in the example shown in FIG. 2), and determines the super frame having the remaining number obtained as the super frame for transmission. You may. Then, the control unit 250 causes the wireless communication unit 220 to repeatedly transmit the frame in the determined super frame.

The evaluation unit 130 of the base station 10 detects the frequency error of the received signal as described in the embodiment of the present disclosure. The demodulation unit 140 sequentially extracts and extracts the received signals received in the same superframe, which is the received signal in which the same frequency error is detected by the evaluation unit 130 and is the same time resource division. Cumulatively synthesize the payload of the received signal. Then, the demodulation unit 140 attempts to demodulate the payload after synthesis.

(motion)
FIG. 13 is a flowchart showing the operation of the sensor terminal 20 according to the second application example. As shown in FIG. 13, first, the control unit 250 of the sensor terminal 20 determines a super frame for transmission using a part of the terminal ID (S404). Then, the control unit 250 generates a frame (S414), and the wireless communication unit 220 transmits the frame as a wireless signal in the determined super frame (S424). Since the subsequent operations are as described with reference to FIG. 7, detailed description thereof will be omitted.

As described above, the demodulation unit 140 of the base station 10 sequentially extracts the received signals received in the same super frame, which are the received signals in which the same frequency error is detected, and extracts the extracted received signals. Cumulatively synthesize the payload.

As described above, according to the second application example, in addition to the frequency error, the received signal from the same sensor terminal 20 can be identified by using the super frame in which the frame is transmitted. Therefore, it is possible to identify the received signal from the same sensor terminal 20 with higher accuracy than when only the frequency error is used for identification.

<5-3. Third application example>
Further, as a third application example, in addition to the frequency error, a mechanism for identifying the source sensor terminal 20 from the hopping pattern of the frequency used is proposed.

(Constitution)
The control unit 250 of the sensor terminal 20 according to the third application example determines a frequency hopping pattern, and causes the wireless communication unit 220 to repeatedly transmit frames according to the determined hopping pattern. Here, specific examples of some hopping patterns will be described with reference to FIGS. 14 to 16.

FIG. 14 is an explanatory diagram showing the hopping pattern 1. As shown in FIG. 14, the hopping pattern 1 is a pattern in which the four frequencies F0 to F4 are switched in the order of F0 → F2 → F1 → F3 → F0. When the control unit 250 determines as a hopping pattern that uses the hopping pattern 1, the first frame is transmitted at the frequency F0, the second frame is transmitted at the frequency F2, and the third frame is transmitted. Is performed at frequency F1, and the fourth frame is transmitted at F3.

FIG. 15 is an explanatory diagram showing the hopping pattern 2. As shown in FIG. 15, the hopping pattern 2 is a pattern in which the four frequencies F0 to F4 are switched in the order of F2 → F3 → F0 → F1 → F2. When the control unit 250 determines as a hopping pattern that uses the hopping pattern 2, the first frame is transmitted at the frequency F2, the second frame is transmitted at the frequency F3, and the third frame is transmitted. Is performed at frequency F0, and the fourth frame is transmitted at F1.

FIG. 16 is an explanatory diagram showing the hopping pattern 3. As shown in FIG. 16, the hopping pattern 3 is a pattern in which the four frequencies F0 to F4 are switched in the order of F0 → F3 → F1 → F2 → F0. When the control unit 250 determines as a hopping pattern that uses the hopping pattern 3, the first frame is transmitted at the frequency F0, the second frame is transmitted at the frequency F3, and the third frame is transmitted. Is performed at frequency F1, and the fourth frame is transmitted at F2.

The control unit 250 may determine the hopping pattern to be used from such a plurality of hopping patterns based on the terminal ID. For example, the control unit 250 can divide the terminal ID by the number of hopping patterns determined according to the number of available frequencies, and determine the hopping pattern according to the obtained remainder value as the hopping pattern to be used. ..

The evaluation unit 130 of the base station 10 evaluates the frequency error of the received signal and the frequency of the carrier wave of the received signal. The demodulation unit 140 extracts two or more received signals whose carrier frequency is switched according to any hopping pattern from among the received signals having the same frequency error evaluated by the evaluation unit 130. The demodulation unit 140 cumulatively synthesizes the payload of the extracted received signal, and attempts to demodulate the combined payload.

Here, the extraction and identification of the received signal using the hopping pattern in addition to the frequency error will be described with reference to a specific example.

FIG. 17 is an explanatory diagram showing an example of a reception result by the base station 10. FIG. 17 shows an example in which a frame is received at frequencies F0 and F2 at time t1 and a frame is received at frequencies F2 and F3 at time t2.

Here, if the frequency error of the received frame is different at each time, the frame transmitted from the same sensor terminal 20 can be identified based on the frequency error. However, if the frequencies of the frames received at each time are the same, it is difficult to identify the frames transmitted from the same sensor terminal 20 only from the frequency error.

Therefore, the demodulation unit 140 identifies the frame transmitted from the same sensor terminal 20 in consideration of the hopping pattern in addition to the frequency error. In the example shown in FIG. 17, the frame (D3) is received at the frequency F2 at the time t2. In the hopping pattern 1, the frequency in the time before the frequency F2 is the frequency F0, and in the hopping pattern 2 or 3, the frequency in the time before the frequency F2 is the frequency F1. However, at the time t1 which is the previous time, the frame is not received at the frequency F1. Therefore, in the demodulation unit 140, the frame (D3) is transmitted according to the hopping pattern 1, and the frame (D1) transmitted at the frequency F0 at the time t1 is transmitted from the same sensor terminal 20 as the frame (D3). It is possible to identify that it is a frame. Along with this, the demodulation unit 140 can also recognize that the other frame (D2) and the frame (D4) are frames transmitted from the same sensor terminal 20.

FIG. 18 is an explanatory diagram showing another example of the reception result by the base station 10. FIG. 18 shows an example in which frames are received at frequencies F0 and F2 at time t3 and frames are received at frequencies F1 and F3 at time t4.

In this example, it is difficult to identify the sensor terminal 20 that is the source of each received signal only from the hopping pattern. Regarding the frame (D7) transmitted at the frequency F1 at the time t4, in the hopping pattern 1, the frequency in the time before the frequency F1 is the frequency F2, and in the hopping pattern 2, the frequency in the time before the frequency F1 is The frequency is F0. Here, at the time t3, which is the previous time, frames are received at both frequencies F0 and F2. Therefore, it is difficult to uniquely identify the frame transmitted from the same sensor terminal 20 as the frame (D7) at time t3. Similarly, for the frame (D8) transmitted at the frequency F3 at the time t4, in the hopping pattern 2, the frequency in the time before the frequency F3 is the frequency F2, and in the hopping pattern 3, the frequency is in the time before the frequency F3. The frequency of is frequency F0. Here, at the time t3, which is the previous time, frames are received at both frequencies F0 and F2. Therefore, it is also difficult to uniquely identify the frame transmitted from the same sensor terminal 20 as the frame (D8) at time t3.

However, the demodulation unit 140 according to the third application example identifies the received signal transmitted from the same sensor terminal 20 based on both the frequency error and the hopping pattern. Therefore, as shown in FIG. 18, even when a reception result that is difficult to identify from the hopping pattern alone is obtained, if the frequency error of the received frame is different at each time, the same sensor terminal is used. The received signal transmitted from 20 can be identified.

(motion)
The configuration of the third application example has been described above. Subsequently, the operation of the third application example will be organized with reference to FIGS. 19 and 20.

FIG. 19 is a flowchart showing the operation of the sensor terminal 20 according to the third application example. As shown in FIG. 19, first, the control unit 250 of the sensor terminal 20 determines a hopping pattern for transmission using the terminal ID (S406). Then, the control unit 250 generates a frame (S416), and the wireless communication unit 220 repeatedly transmits the frame according to the determined hopping pattern (S426). Since the subsequent operations are as described with reference to FIG. 7, detailed description thereof will be omitted.

FIG. 20 is a flowchart showing the operation of the base station 10 according to the third application example. When the radio communication unit 120 of the base station 10 receives the radio signal and outputs the baseband reception signal to the evaluation unit 130, the evaluation unit 130 detects the frequency error and the frequency of the carrier wave (S604). Then, the demodulation unit 140 identifies the frequency that would have been used in the previous section based on the default hopping pattern and the frequency detected by the evaluation unit 130 (S608).

Subsequently, the demodulator 140 stores the payload cut out from the baseband reception signal when there is a payload stored in association with the detected frequency error and the specified frequency (S612 / YES). The payload is synthesized (S616). Then, the demodulation unit 140 performs demodulation processing of the synthesized payload (S620). On the other hand, when there is no payload stored in association with the detected frequency error and the specified frequency (S612 / NO), the demodulation unit 140 demodulates the payload cut out from the baseband received signal. Do (S620).

When demodulation fails in S620 (S624 / NO), the demodulation unit 140 stores the payload targeted for demodulation processing in association with the detected frequency error and the specified frequency (S628). On the other hand, when the demodulation is successful in S620 (S624 / YES), the control unit 150 confirms the terminal ID included in the payload, and causes the wireless communication unit 120 to transmit the ACK to the sensor terminal 20 that is the source of the wireless signal. (S632), the demodulator 140 deletes the payload stored in association with the detected frequency error and the identified frequency (S636).

As described above, according to the third application example, the received signal from the same sensor terminal 20 can be identified by using the hopping pattern in addition to the frequency error. Therefore, it is possible to identify the received signal from the same sensor terminal 20 with higher accuracy than when only the frequency error is used for identification.

In the above, an example of specifying the hopping pattern by referring to the reception result of one section before has been described, but by referring to the reception results of two or more sections, the same sensor terminal 20 can be used in more cases. It becomes possible to identify the received signal.

<< 6. Hardware configuration >>
The embodiments and application examples of the present disclosure have been described above. Each of the above-mentioned information processing for communication is realized by the cooperation between the software and the hardware of the sensor terminal 20 described below. The hardware configuration described below can also be applied to the base station 10.

FIG. 21 is an explanatory diagram showing the hardware configuration of the sensor terminal 20. As shown in FIG. 21, the sensor terminal 20 includes a CPU (Central Processing Unit) 201, a ROM (Read Only Memory) 202, a RAM (Random Access Memory) 203, an input device 208, an output device 210, and the like. It includes a storage device 211 and a communication device 215.

The CPU 201 functions as an arithmetic processing device and a control device, and controls the overall operation in the sensor terminal 20 according to various programs. Further, the CPU 201 may be a microprocessor. The ROM 202 stores programs, calculation parameters, and the like used by the CPU 201. The RAM 203 temporarily stores a program used in the execution of the CPU 201, parameters that change appropriately in the execution, and the like. These are connected to each other by a host bus composed of a CPU bus or the like. The functions of the control unit 250 (in the base station 10, the functions of the evaluation unit 130, the demodulation unit 140, and the control unit 150) are realized by the collaboration between the CPU 201, ROM 202, and RAM 203 and the software.

The input device 208 is an input means for the user to input information such as a mouse, a keyboard, a touch panel, a button, a microphone, a switch, and a lever, and an input control circuit that generates an input signal based on the input by the user and outputs the input signal to the CPU 201. It is composed of such as. By operating the input device 208, the user of the sensor terminal 20 can input various data to the sensor terminal 20 and instruct the processing operation.

The output device 210 includes, for example, a liquid crystal display (LCD) device, an OLED (Organic Light Emitting Diode) device, and a display device such as a lamp. Further, the output device 210 includes an audio output device such as a speaker and headphones. For example, the display device displays an captured image, a generated image, or the like. On the other hand, the voice output device converts voice data and the like into voice and outputs the data.

The storage device 211 is a data storage device configured as an example of the storage unit of the sensor terminal 20 according to the present embodiment. The storage device 211 may include a storage medium, a recording device that records data on the storage medium, a reading device that reads data from the storage medium, a deleting device that deletes the data recorded on the storage medium, and the like. The storage device 211 stores programs and various data executed by the CPU 201.

The communication device 215 is, for example, a communication interface composed of a communication device or the like for connecting to the base station 10.

<< 7. Conclusion >>
As described above, according to the embodiment of the present disclosure, the base station 10 is based on the frequency error of the carrier wave of each received signal without prior communication with the sensor terminal 20 for managing communication resources. It is possible to identify the sensor terminal 20 that is the source of each received signal. Therefore, it is possible to reduce the power consumption for managing communication resources.

Further, by adding the preamble, the super frame, or the hopping pattern in addition to the frequency error, it is possible to further improve the discriminating power of the sensor terminal 20 of the transmission source.

Although the preferred embodiments of the present disclosure have been described in detail with reference to the accompanying drawings, the technical scope of the present disclosure is not limited to such examples. It is clear that a person having ordinary knowledge in the technical field of the present disclosure can come up with various modifications or modifications within the scope of the technical ideas described in the claims. Of course, it is understood that the above also belongs to the technical scope of the present disclosure.

For example, each step in the processing of the base station 10 and the sensor terminal 20 of the present specification does not necessarily have to be processed in chronological order in the order described as a flowchart. For example, each step in the processing of the base station 10 and the sensor terminal 20 may be processed in an order different from the order described in the flowchart, or may be processed in parallel.

Further, it is possible to create a computer program for causing the hardware such as the CPU 201, ROM 202, and RAM 203 built in the base station 10 and the sensor terminal 20 to exhibit the same functions as the configurations of the base station 10 and the sensor terminal 20 described above. Is. A storage medium for storing the computer program is also provided.

In addition, the effects described herein are merely explanatory or exemplary and are not limited. That is, the techniques according to the present disclosure may exhibit other effects apparent to those skilled in the art from the description herein, in addition to or in place of the above effects.

The following configurations also belong to the technical scope of the present disclosure.
(1)
An evaluation unit that evaluates the carrier frequency of the received signal received from other communication devices,
A synthesis processing unit that extracts two or more received signals from a plurality of received signals based on the result of evaluation by the evaluation unit and performs a synthesis process of the two or more received signals.
A communication device.
(2)
The communication device is
Further equipped with an oscillator that generates a periodic signal,
The communication device according to (1) above, wherein the evaluation unit evaluates a difference between the frequency of the carrier wave of the received signal and the frequency of the periodic signal generated by the oscillator.
(3)
The evaluation unit has a plurality of correlation detection units that execute the correlation detection processing of the preamble included in the received signal in parallel.
The plurality of correlation detection units make different adjustments regarding the frequency of the preamble, detect the correlation between the adjusted preamble and the comparison pattern, and detect the correlation between the preamble and the comparison pattern.
The evaluation unit evaluates the amount of adjustment performed by the correlation detection unit that detects the correlation satisfying a predetermined condition as the difference between the frequency of the carrier wave of the received signal and the frequency of the periodic signal generated by the oscillator. The communication device according to (2) above.
(4)
The evaluation unit has two or more sets of the plurality of correlation detection units.
A different comparison pattern is applied to each set of the plurality of correlation detectors.
The evaluation unit evaluates a comparison pattern applied to a correlation detection unit that detects a correlation satisfying a predetermined condition among two or more sets of the plurality of correlation detection units as a preamble included in the received signal. The communication device according to (3).
(5)
The communication device according to (4) above, wherein the comparison pattern is a pattern generated by using a part of identification information that the other communication device may have.
(6)
The item according to any one of (1) to (5) above, wherein the synthesis processing unit extracts the two or more received signals for which the same evaluation result is obtained by the evaluation unit from the plurality of received signals. Communication device.
(7)
The evaluation unit evaluates the division of the time resource in which the received signal is received, and evaluates the division of the time resource.
The synthesis processing unit extracts two or more received signals from the received signals evaluated by the evaluation unit as being received in the same time resource category, any one of the above (1) to (6). The communication device described in.
(8)
The other communication device transmits a signal while regularly switching the frequency of the carrier wave.
The synthesis processing unit detects two or more received signals whose carriers are switched according to a predetermined rule among the received signals having the same amount of adjustment performed by the correlation detection unit that detects the correlation satisfying a predetermined condition. The communication device according to (3) above, which is extracted.
(9)
The communication device is
A demodulation unit that demodulates the composite signal obtained by synthesizing the synthesis processing unit, and
Based on the fact that the demodulation unit succeeds in demodulating the combined signal, a communication unit that transmits a reception confirmation to a communication device having identification information included in the demodulation result, and a communication unit.
The communication device according to any one of (1) to (8) above.
(10)
The processor evaluates the carrier frequency of the received signal received from other communication devices, and
Two or more received signals are extracted from a plurality of received signals based on the evaluation result, and the two or more received signals are combined.
Communication control methods, including.

10 Base station 20 Sensor terminal 30 Application server 110 Periodic signal generation unit 120 Wireless communication unit 130 Evaluation unit 132 Correlation detection unit 134 Addition unit 136 Correlation output unit 138 Comparison unit 140 Demodulation unit 150 Control unit 160 Wired communication unit 220 Wireless communication unit 230 Sensor unit 232 GPS processing unit 240 Carrier wave generation unit 250 Control unit 260 Control unit

Claims (9)

An evaluation unit that evaluates the carrier frequency of the received signal received from another communication device before identification, but does not identify the source terminal.
From the plurality of received signals received from the other communication device before the identification, two or more received signals are extracted based on the evaluation result by the evaluation unit, which does not include the identification result of the source terminal, and the above 2 A synthesis processing unit that performs the above synthesis processing of received signals,
A demodulation unit that demodulates the composite signal obtained by synthesizing the synthesis processing unit, and
Is a communication device equipped with
The communication device is
Further equipped with an oscillator that generates a periodic signal,
The evaluation unit includes a frequency of the carrier wave of the received signal, assessing the difference between the frequency of the periodic signal generated by the oscillator, communication device. The evaluation unit has a plurality of correlation detection units that execute the correlation detection processing of the preamble included in the received signal in parallel.
The plurality of correlation detection units make different adjustments regarding the frequency of the preamble, detect the correlation between the adjusted preamble and the comparison pattern, and detect the correlation between the preamble and the comparison pattern.
The evaluation unit evaluates the amount of adjustment performed by the correlation detection unit that detects the correlation satisfying a predetermined condition as the difference between the frequency of the carrier wave of the received signal and the frequency of the periodic signal generated by the oscillator. The communication device according to claim 1. The evaluation unit has two or more sets of the plurality of correlation detection units.
A different comparison pattern is applied to each set of the plurality of correlation detectors.
The evaluation unit evaluates a comparison pattern applied to a correlation detection unit that has detected a correlation satisfying a predetermined condition among two or more sets of the plurality of correlation detection units as a preamble included in the received signal. Item 2. The communication device according to item 2. The communication device according to claim 3 , wherein the comparison pattern is a pattern generated by using a part of identification information that the other communication device may have. The communication device according to claim 1, wherein the synthesis processing unit extracts the two or more received signals for which the same evaluation result is obtained by the evaluation unit from the plurality of received signals. The evaluation unit evaluates the division of the time resource in which the received signal is received, and evaluates the division of the time resource.
The communication device according to claim 1, wherein the synthesis processing unit extracts the two or more received signals from the received signals evaluated by the evaluation unit as being received in the same time resource category. The other communication device transmits a signal while regularly switching the frequency of the carrier wave.
The synthesis processing unit detects two or more received signals whose carriers are switched according to a predetermined rule among the received signals having the same amount of adjustment performed by the correlation detection unit that detects the correlation satisfying a predetermined condition. The communication device according to claim 2, which is extracted. The communication device according to claim 1, further comprising a communication unit that transmits a reception confirmation to a communication device having identification information included in the demodulation result based on the success of the demodulation unit in demodulating the combined signal. The processor evaluates the carrier frequency of the received signal received from another communication device before identification, but the processor does not identify the source terminal.
Two or more received signals are extracted from a plurality of received signals received from the other communication device before the identification based on the evaluation result that does not include the identification result of the source terminal, and the two or more received signals are extracted. And the synthesis process of
Demodulating the composite signal obtained by the synthesis process and
The including a communication control method,
A communication control method in which the processor evaluates a difference between the frequency of a carrier wave of the received signal and the frequency of a periodic signal generated by an oscillator .

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