WO2017208648A1

WO2017208648A1 - Communication device, communication method, and program

Info

Publication number: WO2017208648A1
Application number: PCT/JP2017/015488
Authority: WO
Inventors: 沢子桐山; 佐藤　雅典
Original assignee: ソニー株式会社
Priority date: 2016-06-01
Filing date: 2017-04-17
Publication date: 2017-12-07
Also published as: JP2017216615A; JP6896377B2

Abstract

[Problem] to improve the success rate of demodulation without being impacted by noise. [Solution] This communication device comprises: a position estimating unit that estimates the position of a communication counterpart device; and a demodulation unit that demodulates a reception signal received from the communication counterpart device on the basis of the propagation delay time according to the position of the communication counterpart device. As a result of this configuration, it is possible to perform demodulation with timing according to the propagation delay time, which in turn makes it possible to increase the success rate of demodulation without being impacted by noise.

Description

COMMUNICATION DEVICE, COMMUNICATION METHOD, AND PROGRAM

The present disclosure relates to a communication device, a communication method, and a program.

Conventionally, for example, the following Patent Document 1 describes a technique that is supposed to provide a base station of a CDMA system that can reduce the failure of initial synchronization acquisition and stably estimate the position.

JP 2002-152802 A

For example, in a CDMA system, in addition to a comparison using a fixed pattern for detecting the start timing of a frame, a TFCI (transport format combination indicator) of the control channel is received, re-encoded and compared, and the start timing of the frame May be detected.

However, even if the comparison is made by re-encoding the TFCI of the control channel in addition to the comparison by the fixed pattern, the synchronization cannot be correctly detected if the noise is large. When the noise is large, it is difficult to determine the frame start timing. If the frame start timing is erroneously recognized, there is a problem that the demodulation success rate decreases.

The technique described in Patent Document 1 describes that position estimation is performed in accordance with propagation characteristics, but does not assume any correct synchronization detection when noise is large.

Therefore, it was desired to increase the success rate of demodulation without being affected by noise.

According to the present disclosure, a position estimation unit that estimates a position of a communication partner device, a demodulation unit that demodulates a received signal received from the communication partner device based on a propagation delay time according to the position of the communication partner device, A communication device is provided.

Further, according to the present disclosure, estimating the position of the communication partner device, demodulating the received signal received from the communication partner device based on the propagation delay time according to the position of the communication partner device; A communication method is provided.

Further, according to the present disclosure, the computer as means for estimating the position of the communication counterpart device, and means for demodulating the received signal received from the communication counterpart device based on the propagation delay time corresponding to the position of the communication counterpart device A program for functioning the program is provided.

Further, according to the present disclosure, a receiving unit that receives a reception signal from a communication counterpart device, a holding unit that holds data based on a reception signal received in the past, and a reception signal newly received from the communication counterpart device, There is provided a communication device comprising: a demodulator that demodulates the received signal newly received from the communication partner device using a portion common to the data by the received signal received in the past.

In addition, according to the present disclosure, receiving a reception signal from a communication partner device, holding data based on a reception signal received in the past, and among the reception signals newly received from the communication partner device, the past And demodulating the received signal newly received from the communication counterpart device using a portion common to the data by the received signal received in the communication method. Is provided.

In addition, according to the present disclosure, among the means for receiving a reception signal from a communication partner apparatus, the means for holding data based on a reception signal received in the past, and the reception signal newly received from the communication partner apparatus, the past A program for causing a computer to function as means for demodulating the reception signal newly received from the communication counterpart device using a portion common to the data by the reception signal received at the same time is provided.

As described above, according to the present disclosure, it is possible to increase the success rate of demodulation without being affected by noise.
Note that the above effects are not necessarily limited, and any of the effects shown in the present specification, or other effects that can be grasped from the present specification, together with or in place of the above effects. May be played.

It is a mimetic diagram showing a communications system concerning each embodiment of this indication. It is a schematic diagram which shows the structure of a terminal. It is a schematic diagram which shows the frame format of the signal which a terminal transmits. It is a schematic diagram which shows the structure of a base station. It is a flowchart which shows the process performed in a base station. It is a schematic diagram which shows the format of position information and propagation delay data. It is a flowchart which shows the process of the demodulation process in a base station. It is a schematic diagram which shows the structure of the base station in 2nd Embodiment. It is a schematic diagram which shows the positional information (GPS data) which a terminal transmits. It is a schematic diagram which shows the trellis diagram of Viterbi decoding in case the number of shift registers is 2 and the coding rate is 1/2. It is a schematic diagram which shows a trellis diagram when the upper 3 bits are known. It is a schematic diagram which shows the database which hold | maintained the reception time of the data which the terminal transmitted, and the decoding result.

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

The description will be made in the following order.
1. 1. First embodiment 1.1. Configuration example of communication system 1.2. Configuration example of base station and terminal 1.3. 1. Processing performed at the base station Second Embodiment 2.1. Configuration of base station in second embodiment 2. Third embodiment

1. 1. First embodiment 1.1. Configuration Example of Communication System FIG. 1 is a schematic diagram illustrating a communication system 1000 according to each embodiment of the present disclosure. In the communication system 1000 according to the present embodiment, the terminal 100 and the base station 300 are configured to be capable of wireless communication. In each of the following embodiments, when the base station 300 demodulates a signal received from the terminal 100, demodulation success is improved by performing demodulation using known information recognized on the base station 300 side. Let In the first embodiment, a method will be described in which a propagation delay based on position information is used for demodulation as known information when base station 300 receives and demodulates data from terminal 100. In the first embodiment, it is assumed that terminal 100 transmits data in a predetermined time slot and does not perform carrier sense.

1.2. Configuration Example of Terminal and Base Station FIG. 2 is a schematic diagram illustrating a configuration of the terminal 100. As illustrated in FIG. 2, the terminal 100 includes a wireless communication unit 101, a control unit 102, and a GPS receiving unit 103.

The wireless communication unit 101 transmits and receives wireless signals according to a predetermined frame format. More specifically, the wireless communication unit 101 performs reception processing of a radio signal transmitted from the base station 300 and transmission processing of a radio signal to the base station 300. More specifically, the radio communication unit 101 converts a radio signal (for example, a 920 MHz band radio signal) transmitted from the base station 300 into an electric signal by an antenna, and performs analog processing and down conversion on the electric signal. As a result, a baseband received signal is output. Also, the wireless communication unit 101 up-converts the baseband transmission signal supplied from the control unit 102, converts the electrical signal obtained by the up-conversion into a wireless signal using an antenna, and transmits the signal.

The control unit 102 controls overall communication in the terminal 100. The control unit 102 controls the wireless communication unit 101 to transmit data, acquire position information from the GPS receiving unit 103, and generate a transmission frame including the position information. The GPS receiving unit 103 acquires position information and time information of the terminal 100 by processing satellite signals transmitted from GPS satellites. Note that the terminal 100 may include other sensors such as an acceleration sensor, a gyro sensor, a temperature sensor, an atmospheric pressure sensor, a sound pressure sensor, and a pulse sensor in addition to the GPS receiving unit 103.

The control unit 102 acquires time information from the GPS receiving unit 103 and controls the timing at which the wireless communication unit 101 can transmit. Since terminal 100 transmits data in a predetermined time slot, based on the time information, terminal 100 transmits data within the time slot having a predetermined time. As a result, the location information of the terminal 100 is transmitted to the base station 300. As described above, the GPS receiving unit 103 receives the GPS signal and acquires the position information and time information of the terminal 100.

FIG. 3 is a schematic diagram showing a frame format of a signal transmitted by the terminal 100. In FIG. 3, a preamble / sync (Preamble / Sync) is a predetermined fixed pattern. On the receiving side, the preamble / sync is used for signal detection and frame synchronization.

The PHY header (PHY Header) is a part in which information related to the physical frame is described. Examples of information on physical frames include the length of PHY Header and subsequent parts (MAC Header, Payload, CRC) and modulation scheme. On the receiving side, the subsequent part can be received according to the information of the PHY header.

The MAC header (MAC Header) is a part that describes address information of the sender and the receiver. The MAC header describes the type of information described in the payload.

Payload is transmission data. For example, when the terminal 100 is a wireless sensor terminal, information (for example, position information, temperature information, etc.) acquired by the sensor is stored. CRC (Cyclic Redundancy Check) enables frame error detection.

FIG. 4 is a schematic diagram showing the configuration of the base station 300. As illustrated in FIG. 4, the base station 300 includes a wireless communication unit 301, a control unit 302, a demodulation unit 303, propagation delay data 304, a storage unit 305, and a terminal location estimation unit 306. Each component shown in FIG. 4 can be constituted by hardware or a central processing unit such as a CPU and a program (software) for causing it to function. When each component is composed of a central processing unit such as a CPU and a program for causing it to function, the program can be stored in a recording medium such as a memory provided in the base station 300.

In FIG. 4, a wireless communication unit 301 transmits and receives wireless signals according to a predetermined frame format. The control unit 302 controls the wireless communication unit 301 to perform transmission and reception. More specifically, the wireless communication unit 301 performs reception processing of a wireless signal transmitted from the terminal 100 and transmission processing of a wireless signal to the terminal 100. More specifically, the wireless communication unit 301 converts a wireless signal (for example, a 920 MHz band wireless signal) transmitted from the terminal 100 into an electrical signal by an antenna, and performs analog processing and down conversion on the electrical signal. As a result, a baseband received signal is output. Also, the wireless communication unit 301 up-converts the baseband transmission signal supplied from the control unit 302, converts the electrical signal obtained by the up-conversion into a wireless signal using an antenna, and transmits the signal.

The demodulator 303 cuts out the payload in the frame shown in FIG. 3 from the received signal based on the synchronization acquired based on the propagation delay data 304 described later. Then, the demodulator 303 tries to demodulate the payload. Whether the demodulation is successful or not is confirmed using the CRC shown in FIG. The demodulator 303 estimates and corrects the propagation path characteristics, and then performs error correction code decoding processing.

The propagation delay data 304 is a database in which a combination of position information such as longitude / latitude and a propagation delay is stored. The propagation delay data 304 will be described in detail later with reference to FIG.

The position information sent from the terminal 100 is demodulated by the demodulator 303. The storage unit 305 holds the position information sent from the terminal 100 obtained by the demodulation process. The terminal position estimation unit 306 acquires the position information of the terminal 100 from the storage unit 305, and estimates the position where the terminal 100 currently exists.

The control unit 302 controls overall communication of the base station 300. The control unit 302 controls the wireless communication unit 301 to perform transmission and reception, and also generates a transmission frame and performs determination based on the received information. When the demodulation unit 303 succeeds in demodulating the payload, the control unit 302 controls the wireless communication unit 301 so that an ACK (reception confirmation signal) is transmitted to the terminal 100 that is the transmission source of the payload.

1.3. Processing Performed at Base Station FIG. 5 is a flowchart showing processing performed at the base station 300. The terminal position estimation unit 306 acquires the position information of the terminal 100 from the storage unit 305, and estimates the position where the terminal 100 currently exists from the history of the position information (step S401). Next, the demodulation unit 303 acquires the location information of the terminal 100 estimated by the terminal location estimation unit 306, compares the location information of the terminal 100 and the location information of the propagation delay data 304, and corresponds to the location information of the terminal 100. A propagation delay time is acquired (step S402).

FIG. 6 is a schematic diagram showing the format of the propagation delay data 304. As shown in FIG. 6, the propagation delay data 304 includes position information represented by latitude (A1, A2) and longitude (B1, B2), and a propagation delay time (Delay 1,) of a point corresponding to the position information. Delay 2, Delay 3, Delay 4) are stored. The propagation delay data 304 is transmitted when there is a change in the relative positional relationship between the terminal 100 and the base station 300, the presence of an object that hinders communication, for example, when a new building is built. It can be updated if there is a change that affects the delay time.

In communication between the terminal 100 and the base station 300, a propagation delay occurs during communication according to the positional relationship between the terminal 100 and the base station 300. Basically, the propagation delay time increases as the distance between the terminal 100 and the base station 300 increases. Further, depending on the positional relationship between the terminal 100 and the base station 300, when there is a building or the like that hinders communication, the propagation delay time increases. Since the position of base station 300 is fixed, propagation delay data 304 as shown in FIG. 6 can be acquired in advance according to the position information of terminal 100. In step S402 in FIG. 5, the propagation delay time (Delay 1, Delay 2, Delay 3, Delay 4) corresponding to the position of the terminal 100 is obtained by applying the position information of the terminal 100 to the propagation delay data 304 in FIG. 6. . If the position information estimated in step S401 and the latitude (A1, A2) and longitude (B1, B2) of the propagation delay data 304 do not completely match, a propagation delay time that matches the position information is calculated by interpolation processing. To do.

Next, the start timing of the received frame is determined from the start time of the time slot and the acquired propagation delay time (step S403). As described above, since terminal 100 performs transmission in a time slot having a predetermined start time, the time delayed by the propagation delay time from the start time of the time slot is the start of the frame received on base station 300 side. Corresponds to timing. As described above, since the base station 300 can determine the frame start timing from the start time of the time slot and the propagation delay time, the normal process of detecting the frame start timing by frame synchronization is not necessary.

When the base station 300 can determine the start timing of the frame, the base station 300 performs demodulation processing on the next received frame (step S404). FIG. 7 is a flowchart showing in detail the demodulation processing in step S404 performed in the base station 300. The demodulator 303 cuts out the received signal based on the start timing of the acquired frame, that is, the time delayed by the propagation delay time from the start time of the time slot, and extracts the preamble portion of the cut-out received signal and the known preamble signal. The propagation path characteristic is estimated by using (Step S601).

Next, in step S602, the payload portion is cut out from the received signal based on the acquired frame start timing. Next, in step S603, the frequency / phase error due to the estimated propagation path characteristic is corrected for the cut payload. Next, in step S604, an error correction code decoding process is performed. At this time, in this embodiment, since the frame start timing can be detected using a known propagation delay signal, the success rate of decoding can be significantly increased. The error correction code is included in the payload shown in FIG. Next, in step S606, frame error detection is performed based on the CRC.

By using the propagation delay time at the corresponding position, which is known information, based on the position information by the above method, the start timing of the received frame can be determined without error. Therefore, the decoding success rate can be greatly improved.

As described above, according to the first embodiment, since the received frame is synchronized based on the propagation delay time obtained from the location information of the terminal 100, the start timing of the received frame can be obtained with high accuracy. It becomes possible. Therefore, the success rate of the demodulation process can be greatly increased.

2. Second Embodiment In the second embodiment, a part of data transmitted by the terminal 100 is used as known information. The configuration of the terminal 100 and the frame format of the signal transmitted by the terminal 100 are the same as those in the first embodiment.

2.1. Configuration of Base Station in Second Embodiment FIG. 8 is a schematic diagram showing a configuration of a base station 300 in the second embodiment. FIG. 8 illustrates a configuration in which the propagation delay data 304 and the terminal location estimation unit 306 are excluded from the configuration of the base station 300 in the first embodiment illustrated in FIG. 4.

In the second embodiment, a part of data already transmitted from the terminal 100 is used as known information. Data that has already been transmitted from the terminal 100 is held in the storage unit 305.

Hereinafter, the decoding process of the error correction code in the base station 300 will be described. For demodulation processing other than error correction code decoding processing, the processing described in the first embodiment may be used, or general demodulation processing may be used.

First, the corrected received signal is demodulated in accordance with the modulation method to obtain a received bit string of 1 and 0. The received bit string acquired here may be either a hard decision or a soft decision.

Next, decoding is performed using the bit information of the known part. Here, it is assumed that terminal 100 sends position information to base station 300. FIG. 9 is a schematic diagram showing position information (GPS data) transmitted by the terminal 100. The position information shown in FIG. 9 corresponds to the payload portion of FIG. In the example shown in FIG. 9, 4 bits are allocated for each digit of position information. For example, for latitude “035 degrees”, 4 bits are assigned to the first digit “0”, 4 bits are assigned to the next 1 digit “3”, and 4 bits are assigned to each digit.

In this case, “035 degrees” represented by the upper 12 bits of latitude does not change unless the terminal 100 moves about 111 kilometers from north to south. Further, “139 degrees” represented by the upper 12 bits of longitude varies depending on the latitude at which the terminal 100 is located, but does not change unless the terminal 100 moves about 20 to 111 kilometers from east to west. Therefore, when the terminal 100 transmits position information at a frequency of once every few minutes, it is considered that the upper 12 bits of latitude and longitude do not change from the information received immediately before, and can be used as known information. . By demodulating the upper 12 bits of latitude / longitude as known information, the success rate of demodulation can be significantly increased.

The flow of demodulation processing is the same as that in FIG. 7 described in the first embodiment. For example, in step S604 of FIG. 7, Viterbi decoding can be performed as decoding of the error correction code. FIG. 10 is a schematic diagram showing a trellis diagram of Viterbi decoding when the number of shift registers is 2 and the coding rate is 1/2 when decoding 7-bit data. In Viterbi decoding, the probability of each path on the trellis diagram is calculated based on the received bit string, and decoding that enables error correction is realized by following the most probable path.

As shown in FIG. 10, when the combination of “0” and “1” has 7 bits, there are a large number of paths as shown in FIG. 10, and decoding may not succeed even with the most probable path.

FIG. 11 is a schematic diagram showing a trellis diagram when the upper 3 bits are known in FIG. In the example of FIG. 11, the upper 3 bits are “1”, “1”, and “0”. In this case, the number of paths to be determined is reduced and there are only four paths, so that the decoding success rate is improved. In this way, by applying the bit string of the known part to the trellis diagram, the paths that need to be determined with certainty are reduced, and then the probability of each path is calculated and the most likely path is selected.

By the above method, according to the second embodiment, the data that has not changed from the data received immediately before that is known information is used for the decoding process, so that the decoding judgment error is reduced and the decoding succeeds. The rate can be improved.

In the above-described example, the data periodically transmitted by the terminal 100 is the position information. However, any information with little temporal change can be applied to various information other than the position information. It can also be applied to humidity information.

3. Third Embodiment In the first embodiment and the second embodiment, the method of decoding received signals in real time using known information has been described. In the third embodiment, received signals are buffered. In addition, decoding using known information is performed on a signal received at an arbitrary time at an arbitrary timing.

FIG. 12 is a schematic diagram showing history data of decoding results. FIG. 12 shows a database holding the reception time of data transmitted by the terminal 100 and the decoding result. The received signal can be stored in the storage unit 305. In the example of FIG. 12, since decoding of the data received at time T2 has failed, decoding is performed again using known information.

When the propagation delay time based on the position information described in the first embodiment is used, the position information where the terminal 100 was present at the time T2 is estimated from the data at the time T1 and the time T3 when the decoding is successful. The propagation delay time data is acquired from the propagation delay data 304 and used for decoding.

In addition, when using the part of the data that does not change as described in the second embodiment, there is no change from the data transmitted by the terminal 100 at time T2 from the data at time T1 and time T3 that have been successfully decoded. The part is used for decoding.

As described above, according to the third embodiment, by performing decoding again using the known information described in the first and second embodiments, the decoding of data that has failed in the past can be performed afterwards. It will be possible to succeed.

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

In addition, the effects described in this specification are merely illustrative or illustrative, and are not limited. That is, the technology according to the present disclosure can exhibit other effects that are apparent to those skilled in the art from the description of the present specification in addition to or instead of the above effects.

The following configurations also belong to the technical scope of the present disclosure.
(1) a position estimation unit that estimates the position of the communication partner apparatus;
A demodulator that demodulates a received signal received from the communication counterpart device, based on a propagation delay time corresponding to a position of the communication counterpart device;
A communication device comprising:
(2) The communication device according to (1), wherein the demodulation unit demodulates the reception signal transmitted from the communication partner device based on a predetermined time slot.
(3) a holding unit that holds a relationship between the position of the communication partner device and the propagation delay time;
The demodulator acquires the propagation delay time according to the position of the communication counterpart device based on the relationship between the position of the communication counterpart device and the propagation delay time, according to (1) or (2). Communication equipment.
(4) The relationship between the position of the communication partner device and the propagation delay time is updated according to a relative positional relationship with the communication partner device or a change in a situation that inhibits communication. 3. The communication device according to 3.
(5) comprising a storage unit for storing the received signal;
The communication device according to any one of (1) to (4), wherein the demodulator demodulates the received signal that has failed in demodulation based on received signals received before and after the received signal.
(6) estimating the position of the communication partner device;
Demodulating a received signal received from the communication counterpart device based on a propagation delay time corresponding to the position of the communication counterpart device;
A communication method comprising:
(7) means for estimating the position of the communication partner device;
Means for demodulating the received signal received from the communication counterpart device based on a propagation delay time corresponding to the position of the communication counterpart device;
As a program to make the computer function as.
(8) a receiving unit that receives a reception signal from the communication partner device;
A holding unit for holding data based on received signals received in the past;
A demodulator that demodulates the reception signal newly received from the communication counterpart device by using a portion of the reception signal newly received from the communication counterpart device that is common to data of the reception signal received in the past. When,
A communication device comprising:
(9) The demodulator receives the received signal newly received from the communication counterpart device by using a part common to the data received by the received signal in the past and having no temporal change. The communication device according to (8), wherein the communication device is demodulated.
(10) A storage unit for storing the received signal is provided,
The communication device according to (8), wherein the demodulator demodulates the received signal that has failed in demodulation based on received signals received before and after the received signal.
(11) receiving a reception signal from the communication partner device;
Holding data from received signals received in the past;
Demodulating the reception signal newly received from the communication counterpart device using a portion of the reception signal newly received from the communication counterpart device that is common to the data of the reception signal received in the past; ,
A communication method comprising:
(12) means for receiving a received signal from the communication partner device;
Means for holding data from received signals received in the past;
Means for demodulating the reception signal newly received from the communication counterpart device by utilizing a portion of the reception signal newly received from the communication counterpart device that is common to the data of the reception signal received in the past; ,
As a program to make the computer function as.

300 base station 301 wireless communication unit 303 demodulation unit 304 propagation delay data 305 storage unit 306 terminal position estimation unit

Claims

A position estimation unit for estimating the position of the communication partner device;
A demodulator that demodulates a received signal received from the communication counterpart device, based on a propagation delay time corresponding to a position of the communication counterpart device;
A communication device comprising:
The communication device according to claim 1, wherein the demodulation unit demodulates the received signal transmitted from the communication partner device based on a predetermined time slot.
A holding unit for holding the relationship between the position of the communication counterpart device and the propagation delay time;
The communication device according to claim 1, wherein the demodulation unit acquires the propagation delay time corresponding to the position of the communication counterpart device based on a relationship between the position of the communication counterpart device and the propagation delay time.
The relationship between the position of the communication partner device and the propagation delay time is updated according to a relative positional relationship with the communication partner device or a change in a situation that inhibits communication. Communication equipment.
A storage unit for storing the received signal;
The communication apparatus according to claim 1, wherein the demodulator demodulates the received signal that has failed in demodulation based on received signals received before and after the received signal.
Estimating the position of the communication partner device;
Demodulating a received signal received from the communication counterpart device based on a propagation delay time corresponding to the position of the communication counterpart device;
A communication method comprising:
Means for estimating the position of the communication partner device;
Means for demodulating the received signal received from the communication counterpart device based on a propagation delay time corresponding to the position of the communication counterpart device;
As a program to make the computer function as.
A receiving unit for receiving a received signal from a communication partner device;
A holding unit for holding data based on received signals received in the past;
A demodulator that demodulates the reception signal newly received from the communication counterpart device by using a portion of the reception signal newly received from the communication counterpart device that is common to data of the reception signal received in the past. When,
A communication device comprising:
The demodulating unit demodulates the received signal newly received from the communication counterpart device using a portion in common with the data received by the received signal received in the past and having no temporal change. The communication apparatus according to claim 8.
A storage unit for storing the received signal;
The communication apparatus according to claim 8, wherein the demodulator demodulates the received signal that has failed in demodulation based on received signals received before and after the received signal.
Receiving a received signal from a communication partner device;
Holding data from received signals received in the past;
Demodulating the reception signal newly received from the communication counterpart device using a portion of the reception signal newly received from the communication counterpart device that is common to the data of the reception signal received in the past; ,
A communication method comprising:
Means for receiving a received signal from a communication partner device;
Means for holding data from received signals received in the past;
Means for demodulating the reception signal newly received from the communication counterpart device by utilizing a portion of the reception signal newly received from the communication counterpart device that is common to the data of the reception signal received in the past; ,
As a program to make the computer function as.