JP2003069472A - Reception terminal device and communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wireless data communication system for conducting data communication using a wireless communication channel, that can carry out desired data communication even when the communication quality is deteriorated due to a situation that arrival of a radio wave is difficult or the effect of an obstacle or the like. SOLUTION: A wireless communication channel between a transmitter terminal and a reception terminal adopts a plurality of transmission protocols (a high-speed protocol with low quality and a low speed protocol with high quality or the like) and the reception terminal transmits control data corresponding to the communication quality to the transmission terminal. The transmission terminal selects a proper protocol depending on the wireless environmental state on the basis of the control data and carries out communication.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a receiving terminal device and a communication system.

[0002]

2. Description of the Related Art In recent years, communication systems for performing communication between communication information terminal devices such as personal computers, information communication terminal devices, and mobile phones have become widespread in the market. In particular, wireless data communication systems using wireless communication lines that do not require wiring and are easy to move devices have begun to spread not only in the industrial field but also in the home (for example, Bluetooth standard). Conventionally,
In such a communication system, communication is performed using only a certain protocol. The protocol is
In the present specification, it means a rule that defines the procedure and mechanism of data communication.

Two typical protocols used in the wireless data communication system will be described with reference to FIGS. 5 and 6. FIG. 5 shows UDP (User Datagram Protoco).
The communication method according to l) is illustrated. In the UDP communication method, the transmitting terminal device assembles data into packets conforming to UDP and transmits the packets to the receiving terminal device. The information transmission direction is limited to one direction (packet transmission direction) from the transmission terminal device to the reception terminal device. The receiving terminal device sends a retransmission request to the transmitting terminal device (for example, if the received data has an error, requests that the same data be retransmitted), and in response, the transmitting terminal retransmits the same data to the receiving terminal. There is no.

FIG. 6 shows a TCP (Transmission Control Pr).
otocol) communication method is illustrated. In the communication method using TCP, every time data is transmitted from the transmitting terminal device to the receiving terminal device, the receiving terminal device transmits control data (ACK or NAK, etc.) for the communication quality of the received data from the receiving terminal device to the transmitting terminal device. Give feedback to If the communication quality of the received data is good, the receiving terminal device returns control data ACK to the transmitting terminal device. The sending terminal device sends the following data to the receiving terminal device. If the communication quality of the received data is poor, the receiving terminal device controls the control data N.
AK is returned to the transmitting terminal device. The transmitting terminal device retransmits the same data to the receiving terminal device.

Therefore, UDP is a protocol which has a higher communication speed than TCP but a lower reliability in communication. That is, in UDP, data is lost when a communication error occurs, and retransmission control is not performed even in the case of loss, so that reliable data transmission cannot be guaranteed. On the other hand, in TCP, since retransmission control is performed when a communication error occurs, data can be sent reliably, but a process for confirming whether data has been transmitted correctly each time data is transmitted (error correction (Retransmission control function for) is executed. Therefore, the data overhead between the transmitting and receiving terminal devices becomes large, the net data portion that can be actually transmitted becomes smaller than that of UDP, and the transmission speed becomes low.

In the conventional communication system, data encoded by a certain encoding method is assembled into a packet of a certain frame format and transmitted. The frame format is the order and amount of information that each of a plurality of pieces of information included in a packet occupy in a packet, or the order that each of a plurality of pieces of information included in a data stream composed of a plurality of packets occupies in a data stream. And means the amount of information.

[0007]

The present invention adaptively changes the communication method when the communication quality (which means the degree to which information is correctly transmitted) deteriorates due to deterioration of the communication environment. It is an object of the present invention to provide a communication system and a receiving terminal device that minimize the unpleasant feeling given to the user.

For example, when performing wireless data communication using UDP, it is assumed that the radio wave environment is bad in the wireless communication section, many transmission errors occur, and data loss occurs. In this case, even if the user wants to reliably send data because the transmission speed may be reduced, the conventional wireless data communication system cannot switch to highly reliable TCP during communication because the protocol is constant. was there. The present invention, in data transmission using a high-speed protocol with low communication quality, when the communication quality deteriorates due to deterioration of the communication environment, etc., switches to a low-speed, high communication quality protocol to reliably transmit desired data. It is an object of the present invention to provide a communication system and a receiving terminal device that operate.

For example, when wireless data communication is performed, it is assumed that the radio wave environment deteriorates in the wireless communication section, many transmission errors occur, and data loss occurs. Even if it is desired to maintain the real-time property of specific data (eg, audio signal) at the expense of communication quality of other data (eg, video signal), the conventional wireless data communication system
The frame format of the transmitted packet was constant. Therefore, there is a problem that the frame format of the packet cannot be switched during communication to maintain the real-time property of the specific data. Maintaining the real-time property means that, for example, the sound output from the speaker of the receiving terminal device is transmitted without interruption.

According to the present invention, when the communication quality is deteriorated due to the deterioration of the communication environment or the like, the frame format of the packet is changed to allocate a larger amount of information to the information (for example, a voice signal) that strongly requires the real-time property. (For example, the number of packets including the frame of the information is increased.) An object is to provide a communication system and a receiving terminal device. By increasing the amount of that information,
The real-time property of the information can be maintained.

It is an object of the present invention to provide a communication system and a receiving terminal device that prevent the deterioration of the communication quality by changing the frame format of the packet when the communication quality deteriorates due to the deterioration of the communication environment. .

[0012]

In order to solve the above problems, the present invention has the following constitution. A first invention is a first data receiving section for receiving encoded data assembled into a packet output from a transmitting terminal device, and a first data extraction section for extracting the encoded data from a packet according to a first protocol.
And a second data extraction unit that extracts the encoded data from a packet according to a second protocol that is slower than the first protocol and has higher communication reliability than the first protocol, the first data extraction unit, or A decoding unit that decodes the encoded data extracted by the second data extraction unit, a data output unit that outputs the decoded data, and a communication quality measurement unit that measures the communication quality of the encoded data. And control data for notifying the communication quality, or control data generation for generating control data for notifying the selected protocol by selecting either the first protocol or the second protocol based on the communication quality And a first data transmission unit that transmits the control data to the transmission terminal device.

A second invention further comprises a condition setting unit for inputting a condition, wherein the control data generation unit is either the first protocol or the second protocol based on the condition and the communication quality. The receiving terminal device according to the first aspect of the invention is characterized in that the receiving terminal device selects whether or not to generate control data for notifying the selected protocol.

In a third aspect of the invention, the data includes a video signal and an audio signal, and in the second protocol, the protocol of the video signal is the same as that of the first protocol, and the data of the audio signal is the same. The receiving terminal device according to the first invention or the second invention is characterized in that the protocols are different.

According to a fourth aspect of the present invention, the first data receiving section receives the encoded data assembled into the packet output from the transmitting terminal device, and the encoded data is extracted from the packet having the first frame format. A first data extraction unit; a second data extraction unit that extracts the encoded data from a packet having a second frame format different from the first frame format;
Data decoding unit that decodes the encoded data output by the data extraction unit or the second data extraction unit, a data output unit that outputs the data decoded by the data decoding unit, and the encoded data A communication quality measuring unit for measuring the communication quality of the device, control data for notifying the communication quality, or one of the first frame format and the second frame format is selected based on the communication quality and selected. A receiving terminal device, comprising: a control data generating unit that generates control data for notifying a frame format; and a first data transmitting unit that transmits the control data to the transmitting terminal device.

A fifth aspect of the present invention further comprises a condition setting unit for inputting a condition, wherein the control data generation unit is based on the condition and the communication quality, and the first frame format or the second frame format. The receiving terminal device according to the fourth invention is characterized in that any one of the above is selected and control data for notifying the selected frame format is generated.

A sixth invention is the reception according to the fourth invention or the fifth invention, wherein in the second frame format, error correction data is added to the first frame format. It is a terminal device.

In a seventh invention, the data includes a video signal and an audio signal, and the second frame format is
The receiving terminal device according to the fourth invention or the fifth invention is characterized in that the ratio of the information amount of the audio signal to the total amount of information is larger than that of the first frame format.

An eighth invention is the invention according to any one of the first to seventh inventions, characterized in that the first data receiving section and the first data transmitting section are wireless communication sections. It is a receiving terminal device.

A ninth invention is a transmitting terminal device, and the receiving terminal device is any one of the first invention to the third invention.
And a second data receiving unit that receives the control data, a data input unit that inputs the data, and a data encoding unit that encodes the data to generate encoded data. A first packet assembling unit for assembling the encoded data into packets according to the first protocol, a second packet assembling unit for assembling the encoded data into packets according to the second protocol, and based on the control data Second data for selecting the first protocol or the second protocol as the protocol of the packet to be transmitted, and transmitting the encoded data assembled into a packet according to the selected protocol to the receiving terminal device. A communication system, comprising: a transmitter.

A tenth invention comprises a transmitting terminal device and a receiving terminal device according to any one of the fourth to seventh inventions, wherein the transmitting terminal device receives the control data. A second data receiving unit, a data input unit for inputting data, a data encoding unit for encoding the data to generate encoded data, and a first unit for assembling the data into packets in the first frame format. Packet assembling unit, a second packet assembling unit for assembling the data into packets in the second frame format, and the first frame format or the frame format of the data to be transmitted based on the control data. A second frame format is selected and the encoded data assembled into packets in the selected frame format Second to be transmitted to the receiving terminal device
And a data transmission unit of the above.

An eleventh invention is characterized in that the first data receiving section, the first data transmitting section, the second data receiving section and the second data transmitting section are wireless communication sections. 9 is a communication system according to the ninth invention or the tenth invention.

In the communication system according to the ninth aspect of the invention, the transmitting terminal device and the receiving terminal device are equipped with functional units capable of transmitting and receiving data using a plurality of protocols having different characteristics, and the protocol is changed as necessary. You can switch. For example, in wireless data communication using a high-speed protocol with low communication quality, when a communication error exceeding a preset error condition occurs in a wireless communication section, the receiving terminal device sends control data to the transmitting terminal device.
Based on the control data, the transmitting terminal device can switch a high-speed protocol with low communication quality to a low-speed protocol with high communication quality to realize reliable data communication. Using the receiving terminal device according to the first aspect of the invention,
The communication system of the invention can be realized.

In the communication system of the ninth invention having the receiving terminal device of the second invention, the receiving terminal device selects an appropriate protocol based on the condition input from the condition setting unit and the measurement result of the communication quality of the received data. Then, the sending terminal device is instructed to send the data according to the appropriate protocol. The transmitting terminal device can transmit the encoded data using an appropriate protocol.

In the communication system of the ninth invention having the receiving terminal device of the third invention, when the communication quality deteriorates due to the deterioration of the communication environment or the like, the amount of information is large and the demand for the real-time property is relatively small. A protocol (for example, UDP) suitable for the characteristic is applied to the video signal, and a protocol (for example, TCP) suitable for the characteristic is applied to the audio signal having a small amount of information and a strong demand for real-time property. By applying an appropriate protocol for each signal, these signals can be transmitted with a certain communication quality or higher.

In the communication system of the tenth aspect of the invention, the transmitting terminal device and the receiving terminal device are equipped with a functional unit capable of transmitting and receiving data using a plurality of types of packets having different frame formats, and if necessary, You can switch the frame format of the packet. For example, in wireless data communication using a packet having a standard frame format, when a communication error exceeding a preset error condition occurs in a wireless communication section, the receiving terminal device sends control data to the transmitting terminal device. Based on the control data, the transmitting terminal device switches the standard frame format to a frame format that allocates a large amount of information to a frame of a signal that causes a great discomfort to the user when a transmission error is large (changes the frame format). .). As a result, the signal can be transmitted with a certain communication quality or higher. For example, the real-time property of the signal can be maintained. The communication system of the tenth invention can be realized by using the receiving terminal device of the fourth invention.

A tenth aspect including the receiving terminal device of the fifth invention
In the communication system of the invention, the receiving terminal device determines an appropriate frame format based on the condition input from the condition setting unit and the measurement result of the communication quality of the received data, and the data is transmitted in a packet having the appropriate frame format. To the transmitting terminal device.
The transmitting terminal device can transmit the encoded data in a packet having an appropriate frame format.

A tenth aspect including the receiving terminal device of the sixth invention
In the communication system of the present invention, when the communication quality deteriorates due to deterioration of the communication environment or the like, the frame format is changed to the one to which error correction data is added. As a result, the signal can be transmitted with a certain communication quality or higher.

A tenth aspect including the receiving terminal device of the seventh invention
In the communication system of the invention of claim 1, when the communication quality deteriorates due to deterioration of the communication environment or the like, a larger amount of information is assigned to the voice signal which strongly requires the real-time property. Thereby, the real-time property of the signal can be secured. Assigning a larger amount of information to an audio signal means allocating a larger proportion to the audio signal within a frame, increasing the size of the audio signal frame, or increasing the frequency of transmission of the audio signal frame, etc. Realized by.

The wireless communication system generally has a limited transmission capacity, and the communication environment is likely to change due to various factors (the communication environment is likely to deteriorate). Therefore, the present invention is particularly suitable for a wireless communication system and its receiving terminal device.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments specifically showing the best mode for carrying out the present invention will be described with reference to the drawings.

<< First Embodiment >> A wireless data communication system according to a first embodiment will be described with reference to FIG. 1 is a block diagram showing the configuration of a wireless data communication system according to a first embodiment of the present invention. In FIG. 1, 100 is a transmitting terminal device, and 10
1 is a receiving terminal device. The transmitting terminal device 100 includes a data input unit 11, a data encoding unit 12, a first protocol packet assembling unit 13, a second protocol packet assembling unit 14, a data transmitting unit 15, and a protocol switching unit 16,
It has a data receiving unit 17 and an antenna 18. The receiving terminal device 101 includes an antenna 21, a data receiving unit 22, a first protocol data extracting unit 23, a second protocol data extracting unit 24, a data decoding unit 25, and a data output unit 2.
6, a communication quality measuring unit 27, a control data generating unit 28, and a data transmitting unit 29.

In the transmission system of the first embodiment, the first protocol (UDP in the embodiment) for unilaterally transmitting information from the transmitting terminal device to the receiving terminal device, and transmitting information from the transmitting terminal device to the receiving terminal device. Secondly, a response such as ACK or NAK is returned from the receiving terminal device to the transmitting terminal device each time
And the protocol (TCP in the embodiment) are selectively used as the communication protocol.

The transmitting terminal device 100 takes in the data to be transmitted from the data input section 11. Data encoding unit 12
Performs compression coding and error correction coding on the captured data and outputs the coded data. The encoded data has a smaller amount of information as compared with the captured data, and even if a transmission error occurs due to a disturbance during transmission, the transmission error can be detected / corrected.

First protocol packet assembling unit 13
Assembles the encoded data into packets according to a fixed frame format and a first protocol. In the first embodiment, the first protocol is UDP with high speed and low communication reliability. The second protocol packet assembling unit 14 assembles the encoded data into packets according to a fixed frame format and the second protocol. In the first embodiment, the second protocol is TCP, which has low communication speed and high communication reliability. The packet assembled according to any one of the protocols is transmitted from the data transmitting unit 15 through the antenna 18, and is received by the receiving terminal device 101 via the wireless communication line.

The control data transmitted from the receiving terminal device 101 through the wireless communication line and received through the antenna 18 is received by the data receiving section 17. The received control data includes protocol selection information. The control data is sent to the protocol switching unit 16. The protocol switching unit 16 sends a control signal to the first protocol packet assembling unit 13 and the second protocol packet assembling unit 14 based on the protocol selection information to operate either of the two packet assembling units. Protocol selection information is
It is information instructing which of the first protocol and the second protocol is used for communication.

The receiving terminal device 101 is the transmitting terminal device 10
Data transmitted from 0 through the wireless communication line is received by the data receiving unit 22 through the antenna 21. The data receiving unit 22 sends the received data packet to the first protocol data extracting unit 23 and the second protocol data extracting unit 24. The first protocol data extraction unit 23 or the second protocol data extraction unit 24 selectively operates according to the control signal output from the control data generation unit 28. Either of the data extraction units 23 or 24 extracts the encoded data from the received packet and transmits the encoded data to the data decoding unit 25. Data decoding unit 25
Decodes the encoded data (including error detection / correction and decompression), and transmits the decoded data to the data output unit 26. The data decoding unit 26 outputs the decoded data.

When the data decoding unit 25 decodes encoded data (especially at the time of error detection / correction), the communication quality measuring unit 2
7 detects the error rate of encoded data. What is the error rate?
For example, the number of erroneous information with respect to a certain amount of information, the number of error information detected within a certain period of time, or the frequency of occurrence of a certain amount of errors or more within a certain period of time. Communication quality measuring unit 27
Transmits the detected error rate information to the control data generation unit 28. The control data generation unit 28 determines which protocol should be used for wireless communication based on the error rate information. The control data generation unit 28 generates control data and control signals including protocol selection information instructing a protocol to be used. The control data generator 28
The control data is transmitted to the data transmitting unit 29, and the control signal is transmitted to the first protocol data extracting unit 23 and the second protocol data extracting unit 24. Data transmitter 29
Transmits the control data to the transmitting terminal device 100 through the antenna 21 and the wireless communication line.

The control data generation unit 28 determines to use the first protocol (UDP) having low communication reliability but high speed, for example, when the error rate of the transmission data is lower than the constant threshold A. For example, if the error rate of transmission data is higher than a certain threshold B, the control data generation unit 28 determines to use the second protocol (TCP) that is slow but has high communication reliability. The threshold A and the threshold B may be the same, or hysteresis may be provided (the threshold A may be lower than the threshold B).

When the transmission error occurring in the wireless communication line is sufficiently low and the first protocol (UDP) is selected, communication is performed at a high transmission rate. In the case where the transmission error occurring in the wireless communication line is high and the data decoding unit 25 cannot correct the error due to the large loss of the received encoded data and the second protocol (TCP) is selected, A packet retransmission request (for example, a NAK signal) is transmitted to the transmitting terminal device 100 through the data transmitting unit 29. The transmitting terminal device 100 retransmits the packet. For example, since the packet number is added to the header of the TCP packet, specify the packet that could not be received,
The packet can be requested to be retransmitted. As a result, the encoded data can be reliably transmitted even in a bad wireless communication environment.

According to the control data and the like, the transmitting terminal device 100
The protocol used for the packet assembled by the receiver and the protocol of the packet extracted by the receiving terminal device 101 are
Always match. According to the wireless communication system of the first embodiment, in the wireless communication line between the transmission terminal device and the reception terminal device, a plurality of transmission protocols (low communication reliability and high speed protocol, high communication reliability and low speed protocol, etc. ), The protocol can be switched and used depending on the wireless environment condition.

In the wireless communication system of the first embodiment,
The control data generation unit 28 of the receiving terminal device 101 determines which protocol should be used for wireless communication.
In another embodiment, the control data generation unit of the receiving terminal device only generates control data including error rate information and does not determine which protocol should be used.
The protocol switching unit of the transmitting terminal device determines which protocol should be used for wireless communication based on the error rate information included in the control data sent from the receiving terminal device.

The first protocol packet assembling unit 13 or the second protocol packet assembling unit 14 selectively operates according to the control signal from the protocol switching unit. First
The packet assembled by the protocol packet assembling unit 13 or the second protocol packet assembling unit 14 includes information about which protocol the packet uses. The first protocol data extraction unit 23 and the second protocol data extraction unit 24 of the receiving terminal device are configured to detect which protocol is included in the received packet and which protocol the packet uses.
Operates selectively.

<< Second Embodiment >> A wireless data communication system according to a second embodiment will be described with reference to FIG. Second Embodiment FIG. 2 is a block diagram of a wireless data communication system according to a second embodiment of the present invention.
The receiving terminal device 201 according to the second embodiment includes a condition setting unit 202. Otherwise, the wireless data communication system of the second embodiment is the same as the wireless data communication system of the first embodiment.

The operator of the receiving terminal device 201 uses a condition setting unit 202 (including a keyboard, for example) to set a threshold value for switching from UDP to TCP and a threshold value for switching from TCP to UDP in order to ensure the reliability of transmission data. It can be set arbitrarily. The control data generation unit 28 uses the set condition (threshold value) and communication quality measurement unit 2
The first protocol or the second protocol is selected as the communication protocol based on the error rate measured by 7.
For example, when a communication error frequently occurs due to the influence of disturbance on the wireless communication line, a large amount of data is lost, and the data error rate exceeds the threshold set by the condition setting unit 202, the control data generation unit 28 It is determined to switch the protocol from UDP to TCP, and control data including an instruction to switch the protocol to TCP is transmitted to the transmitting terminal device 100 via the data transmitting unit 29.

After switching to the TCP protocol, the error rate of the data measured by the communication quality measuring unit 27 is the condition setting unit 202.
If the frequency is lower than the threshold set in step 1, that is, if the frequency of occurrence of transmission error is low and the frequency of the reception terminal device 201 sending a retransmission request to the transmission terminal device 100 is sufficiently low, the control data generation unit 28 sends TCP. Determines to switch the protocol from the UDP to the UDP, and transmits control data including an instruction to switch the protocol to the UDP to the transmitting terminal device 100 via the data transmitting unit 29. As described above, according to the wireless communication system of the second embodiment, data communication can be performed by switching to an appropriate protocol each time, based on the error occurrence status of the wireless communication line.

<< Third Embodiment >> A wireless data communication system according to a third embodiment will be described with reference to FIGS. 3 and 7. Third Embodiment FIG. 3 is a block diagram showing the configuration of a wireless data communication system according to a third embodiment of the present invention. In FIG. 3, 300 is a transmitting terminal device and 301 is a receiving terminal device. Transmission terminal device 300
Is a data input unit 11, a data encoding unit 12, a packet assembly unit 313 in the first frame format, a packet assembly unit 314 in the second frame format, a data transmission unit 15, a frame format switching unit 316, and data reception. It has a section 17 and an antenna 18. The receiving terminal device 101 includes an antenna 21, a data receiving unit 22, a first frame format data extracting unit 323, a second frame format data extracting unit 324, a data decoding unit 25, a data output unit 26, and communication quality measurement. It has a unit 27, a control data generation unit 28, and a data transmission unit 29.

In the wireless data communication system of the third embodiment, the optimum frame format is selected from the two types of frame formats, and the data packet of that frame format is transmitted from the transmitting terminal device 300 to the receiving terminal device 301. 7A and 7B are diagrams schematically showing packet configurations (data stream configurations) of two types of frame formats in the wireless communication system of the third embodiment. In the wireless data communication system of the third embodiment, the data stream of the image data with audio is transmitted according to the TCP protocol.
The data stream includes video packets including frames of video signals and audio packets including frames of audio signals. A video packet including a frame of a video signal and an audio packet including a frame of an audio signal may have the same information amount, and different information amounts (for example, the information amount of a video packet is greater than the information amount of an audio packet). Is also large.)

FIG. 7A shows the structure of the data stream in the normal state. Since the information amount of the video signal is larger than the information amount of the audio signal, the number of video packets including the frame of the video signal is larger than the number of audio packets including the frame of the audio signal. FIG. 7B shows the structure of the data stream when the reception state of the wireless communication line deteriorates. When the reception condition of the wireless communication line deteriorates, the state shown in FIG.
As shown in (b), an audio packet is incorporated into a data stream where a video packet should be inserted (see FIG. 7A).

When the reception of the video signal is interrupted, the receiving terminal device repeatedly outputs, for example, the video signal of the immediately preceding frame which has been correctly received. As a result, the screen displayed on the display does not distort for a certain amount (for example, the screen may seem to freeze for a moment, but the entire screen does not turn into noise). Can be prevented from receiving. However, since the audio signal cannot be subjected to data interpolation using the temporal and spatial correlation as compared with the video signal, the interruption of the audio signal directly gives the user an unpleasant feeling. The interruption of the audio signal sometimes causes a large amount of noise, which may damage the speaker or the user's ear.

When the reception condition of the wireless communication line deteriorates,
In accordance with the TCP protocol, the receiving terminal device 301 frequently sends data retransmission requests to the transmitting terminal device 300. When the transmitting terminal device 300 repeatedly transmits the same data,
Since the data transmission is delayed, it becomes difficult to maintain the real-time property of the video signal and the audio signal. Therefore, in the wireless data communication system of the third embodiment, when the reception state of the wireless communication line deteriorates, the transmission rate of audio packets is increased. This ensures the real-time property of the audio signal which is difficult to interpolate temporally and spatially. Although shown schematically in FIG. 7, since the information amount of the audio signal is generally much smaller than that of the video signal, it is possible to significantly increase the transmission rate of the audio signal by replacing a few video packets with audio packets. Can be up.

The transmitting terminal device 300 takes in the data to be transmitted from the data input section 11. Data encoding unit 12
Performs compression coding and error correction coding on the captured data and outputs the coded data. The encoded data has a smaller amount of information as compared with the captured data, and even if a transmission error occurs due to a disturbance during transmission, the transmission error can be detected / corrected.

The packet assembling unit 313 in the first frame format converts the encoded data into the first frame format (frame format in FIG. 7A) and TC.
Assemble into packets according to P's protocol. The packet assembling unit 314 in the second frame format converts the encoded data into the second frame format (FIG. 7B).
Frame format) and TCP protocol. The packet assembled in either frame format is sent to the data transmission unit 15
The signal is transmitted through the antenna 18 and received by the receiving terminal device 301 through the wireless communication line.

The control data transmitted from the receiving terminal device 301 via the wireless communication line and received via the antenna 18 is received by the data receiving unit 17. The received control data includes frame format selection information.
The control data is sent to the frame format switching unit 316. The frame format switching unit 316 sends a control signal to the packet assembling unit 313 in the first frame format and the packet assembling unit 314 in the second frame format based on the frame format selection information. Operate either.
The frame format selection information is information indicating which of the first frame format and the second frame format is used for communication.

The receiving terminal device 301 is the transmitting terminal device 30.
Data transmitted from 0 through the wireless communication line is received by the data receiving unit 22 through the antenna 21. The data receiving unit 22 sends the received data packet to the data extracting unit 323 having the first frame format and the data extracting unit 324 having the second frame format. The data extraction unit 323 of the first frame format or the data extraction unit 324 of the second frame format selectively operates according to the control signal output from the control data generation unit 28. One of the data extraction units 323 or 324 extracts the encoded data from the received packet and transmits the encoded data to the data decoding unit 25. Data decoding unit 25
Decodes the encoded data (including error detection / correction and decompression), and transmits the decoded data to the data output unit 26. The data decoding unit 26 outputs the decoded data.

When the data decoding unit 25 decodes encoded data (especially at the time of error detection / correction), the communication quality measuring unit 2
7 detects the error rate of encoded data. The communication quality measuring unit 27 uses the information on the detected error rate as the control data generating unit 2
8 is transmitted. The control data generation unit 28 determines which frame format should be used for wireless communication based on the error rate information. Control data generator 2
8 generates control data and control signals including frame format selection information indicating a frame format to be used. The control data generation unit 28 transmits the control data to the data transmission unit 29, and transmits the control signal to the data extraction unit 323 having the first frame format and the data extraction unit 324 having the second frame format. The data transmission unit 29 transmits the control data to the transmission terminal device 300 through the antenna 21 and the wireless communication line.

The control data generation unit 28 determines to use the normal first frame format if the error rate of the transmission data is lower than the constant threshold A, for example. The control data generation unit 28 determines to use the second frame format if the error rate of the transmission data is higher than a certain threshold B, for example. The threshold A and the threshold B may be the same, or hysteresis may be provided (the threshold A may be lower than the threshold B).

When the transmission error occurring in the wireless communication line is sufficiently low and the first frame format is selected, the video signal and the audio signal are transmitted in real time. The transmission error that occurs in the wireless communication line is high,
When the frame format is selected, even if the video signal occasionally freezes on the display, the real-time property of the audio signal is maintained, so that the discomfort experienced by the user can be kept below a certain level. I can. As a result, even in a bad wireless communication environment, it is possible to prevent the discomfort experienced by the user from deteriorating beyond a certain level.

Based on the control data and the like, the transmitting terminal device 300
The frame format used for the packet assembled by the receiver and the frame format of the packet extracted by the receiving terminal device 101 always match. According to the wireless communication system of the first embodiment, the wireless communication line between the transmitting terminal device and the receiving terminal device is provided with a plurality of frame formats, and the frame formats can be switched and used depending on the wireless environment condition.

In the wireless communication system of the third embodiment,
The control data generation unit 28 of the receiving terminal device 301 determines which frame format should be used for wireless communication. In another embodiment, the control data generator of the receiving terminal device only generates the control data including the error rate information and does not determine which frame format should be used. The frame format switching unit of the transmission terminal device determines which frame format should be used for wireless communication based on the error rate information included in the control data sent from the reception terminal device.

The packet assembling unit 313 in the first frame format or the packet assembling unit 314 in the second frame format selectively operates according to the control signal of the frame format switching unit. The packet assembled by the packet assembling unit 313 in the first frame format or the packet assembling unit 314 in the second frame format includes information about which frame format the packet uses. The data extraction unit 323 of the first frame format and the data extraction unit 324 of the second frame format of the receiving terminal device follow the information contained in the received packet as to which frame format the packet uses. , Works selectively.

In the wireless data communication system of the third embodiment, the configurations of a plurality of data streams (including a plurality of packets) are switched and used. In another embodiment, each packet includes a video signal and an audio signal. Usually, the order and amount of information that each of a plurality of pieces of information (video signal and audio signal) included in the packet occupy in the packet are constant (determined by the amount of information of the video signal and the amount of information of the audio signal). However, when the communication environment deteriorates and the data error rate increases, the amount of information assigned to the video signal in the packet is reduced and the amount of information of the audio signal is increased. This ensures the real-time property of the audio signal.

A wireless communication system according to the first embodiment and a third embodiment.
You may combine with the wireless communication system of. If the communication environment is good, the transmitting terminal device uses the UDP protocol and FIG.
Assemble packets in the frame format of (a),
The packet is transmitted to the receiving terminal device. If the communication environment deteriorates and the error rate of the transmission data exceeds the first threshold value, the transmitting terminal device assembles a packet with the TCP protocol and the frame format of FIG. 7A, and transmits the packet to the receiving terminal device. To do. If the communication environment further deteriorates and the error rate of the transmission data exceeds the second threshold, the transmitting terminal device assembles a packet with the TCP protocol and the frame format of FIG. 7B, and the packet is transmitted to the receiving terminal device. To transmit.

<< Fourth Embodiment >> A wireless data communication system according to a fourth embodiment will be described with reference to FIGS. The wireless data communication system according to the fourth embodiment of the present invention has the same configuration as the wireless data communication system according to the third embodiment (FIG. 3). In the wireless data communication system according to the fourth embodiment, the optimum frame format is selected from two types of frame formats, and the data packet of the frame format is transmitted from the transmission terminal device 300 to the reception terminal device 301. The wireless data communication system according to the fourth embodiment is the same as the third embodiment.
This wireless communication system has two different frame formats.

FIGS. 8A and 8B are diagrams schematically showing packet configurations (data stream configurations) of two types of frame formats in the wireless communication system of the fourth embodiment, respectively. In the wireless data communication system according to the fourth embodiment, a data stream of image data with audio is transmitted according to the TCP protocol. The data stream is a video packet containing frames of a video signal,
An audio packet containing a frame of an audio signal. A video packet including a frame of a video signal and an audio packet including a frame of an audio signal may have the same information amount, and different information amounts (for example, the information amount of a video packet is greater than the information amount of an audio packet). Is also large.)

FIG. 8A shows the structure of the data stream in the normal state (the same as FIG. 7A). The data stream has only video packets containing video signals and audio packets containing audio signals. FIG. 8B shows the structure of the data stream when the reception state of the wireless communication line deteriorates. When the reception state of the wireless communication line deteriorates, as illustrated in FIG. 8B, the error check packet is included in addition to the video packet and the audio packet. The error check packet has, for example, a CRC code (Cyclic Redundancy Check Code). Generally, the data encoding unit 12 generates a CRC code. Second
The packet assembling unit 314 in the frame format of
An RC code may be generated.

In the wireless communication system of the fourth embodiment, when the wireless communication line is in a bad environment and communication errors occur frequently, an error check packet having a stronger error correction function is added to the data stream. This makes it possible to more strongly correct the erroneous data caused by the communication error.

<< Fifth Embodiment >> A wireless data communication system according to a fifth embodiment will be described with reference to FIG. Fourth Embodiment FIG. 4 is a block diagram of a wireless data communication system according to a fifth embodiment of the present invention.
The receiving terminal device 401 according to the fifth embodiment includes a condition setting unit 202. Otherwise, the wireless data communication system of the fifth embodiment is the same as the wireless data communication system of the third embodiment (FIG. 3).

The operator of the receiving terminal device 401 changes the threshold value from the first frame format to the second frame format and the second frame format to the first frame format in order to secure the reliability of the transmission data. The condition setting unit 202 sets the threshold to be switched.
It can be arbitrarily set through (including a keyboard, for example). The control data generation unit 28 selects the first frame format or the second frame format as the communication frame format based on the set condition (threshold value) and the error rate measured by the communication quality measurement unit 27.

<< Sixth Embodiment >> A wireless data communication system according to a sixth embodiment will be described with reference to FIG. The wireless data communication system of the sixth embodiment has the same configuration as the wireless data communication system of the second embodiment (FIG. 2). The wireless communication system according to the sixth embodiment transmits image data and audio data by different protocols suitable for each data. When receiving the image data with sound in a state where the real-time property is ensured, it is necessary to receive the sound data completely prior to the image data. Therefore, in an environment of a wireless communication line where a communication error is likely to occur, a method of transmitting image data and audio data by different protocols suitable for each characteristic is more suitable than transmitting by the same protocol.

For example, an audio signal that has a small amount of information but is not allowed to have data loss is sent by TCP, and image data that has a large amount of information and is allowed to have data loss is faster than the audio signal even if the reliability is low. It is suitable to send by the UDP protocol. In the wireless data communication system according to the sixth embodiment, if the error rate of the transmission data measured by the communication quality measuring unit 27 is sufficiently low, both the video signal and the audio signal are transmitted according to the UDP protocol (referred to as a first protocol). .). When the error rate of the transmission data measured by the communication quality measuring unit 27 exceeds a certain threshold, the video signal is UDP
And a voice signal according to the TCP protocol (referred to as a second protocol).

The operator of the receiving terminal device 201 operates from the first protocol to the second protocol in order to secure the reliability of the transmission data.
The threshold for switching to the protocol and the threshold for switching from the second protocol to the first protocol can be arbitrarily set through the condition setting unit 202 (including a keyboard, for example). The control data generation unit 28 selects the first protocol or the second protocol as the communication protocol based on the set condition (threshold value) and the error rate measured by the communication quality measurement unit 27. For example, a communication error frequently occurs due to the influence of disturbance on the wireless communication line, a large amount of data is lost, and the error rate of the data is determined by the condition setting unit 20.
When the threshold value set in 2 is exceeded, the control data generation unit 2
Reference numeral 8 determines that the transmission protocol of the video signal remains UDP, and the transmission protocol of the audio signal is switched from UDP to TCP (switch from the first protocol to the second protocol), and is transmitted via the data transmission unit 29. Control data including an instruction to switch the protocol to the second protocol is transmitted to the terminal device 100.

After switching to the second protocol, the error rate of the data measured by the communication quality measuring unit 27 is the condition setting unit 202.
If the frequency is lower than the threshold set in step 1, that is, if the frequency of occurrence of transmission error is low and the frequency of the reception terminal device 201 sending a retransmission request to the transmission terminal device 100 is sufficiently low, the control data generation unit 28 causes the video The signal transmission protocol remains UDP, and the audio signal transmission protocol is switched from TCP to UDP (from the second protocol to the first protocol).
(Switching to the first protocol), and the first protocol is set to the transmitting terminal device 100 via the data transmitting unit 29.
Control data including an instruction to switch to the protocol is transmitted. As described above, according to the wireless communication system of the sixth embodiment, data communication can be performed by switching to an appropriate protocol suitable for the characteristics of the signal each time, based on the error occurrence status of the wireless communication line.

The above embodiments have illustrated wireless data communication systems. A wireless data communication system that is easily affected by disturbance and has a small transmission capacity is suitable for application of the present invention. However, the present invention can also be applied to a wired data communication system.

In the communication system of the above embodiment,
Two types of protocols or two types of frame formats were switched. The embodiment is an exemplification, and more kinds of protocols or frame formats can be adaptively switched.

[0076]

As described above in detail in the embodiments, the communication system of the present invention has the following effects. First, a data communication system for performing communication between a transmitting terminal device and a receiving terminal device is provided with a plurality of transmission protocols (low communication quality and high speed protocol, high communication quality and low speed protocol, etc.) Select and use a protocol that is suitable for your environment. As a result, even if the environment of the communication line deteriorates, it is possible to secure communication quality of a certain level or higher for the transmission data.

Secondly, based on the priorities of a plurality of signals (for example, the priority of information requiring real-time property (for example, voice signal) is increased), a transmission packet is transmitted when the environment of the communication line deteriorates. The frame format configuration of is changed, and signals with higher priority are transmitted with priority.
As a result, even when the environment of the communication line is deteriorated, it is possible to secure communication quality of the transmission data above a certain level (for example, real-time property of information can be secured). Thirdly, if the communication quality is poor, the frame format is changed to add data for error correction,
Apply more robust error correction. This makes it possible to prevent deterioration of communication quality. Fourth, when the data includes a video signal and an audio signal, a protocol suitable for the characteristics of the signal is applied to each signal. The receiving terminal device receives a packet according to a different protocol for each signal. As a result, even when the environment of the communication line is deteriorated, it is possible to ensure communication quality of a certain level or higher for each signal according to the characteristics of the signal.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a wireless communication system according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a wireless communication system according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a wireless communication system according to a third embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a wireless communication system according to a fifth embodiment of the present invention.

FIG. 5 is a diagram showing a packet transmission procedure by UDP.

FIG. 6 is a diagram showing a packet transmission procedure by TCP.

FIG. 7 (a) shows a data stream configuration in a normal state in a wireless communication system according to a third embodiment of the present invention. FIG. 7 (b) shows a wireless communication system according to a third embodiment of the present invention. The figure which shows the data stream structure when the state of the wireless communication line is bad

FIG. 8 (a) shows a data stream configuration in a normal state in a wireless communication system according to a fourth embodiment of the present invention. FIG. 8 (b) shows a wireless communication system according to a fourth embodiment of the present invention. The figure which shows the data stream structure when the state of the wireless communication line is bad

[Explanation of symbols]

100, 300 transmitting terminal device 101, 201, 301, 401 receiving terminal device 11 data input unit 12 data encoding unit 13 first protocol packet assembling unit 14 second protocol packet assembling unit 15 data transmitting unit 16 protocol switching Unit 17 data receiving unit 18, 21 antenna 22 data receiving unit 23 first protocol data extracting unit 24 second protocol data extracting unit 25 data decoding unit 26 data output unit 27 communication quality measuring unit 28 control data generating unit 29 data transmission unit 202 condition setting unit 313 packet assembly unit 314 in first frame format packet assembly unit 316 in second frame format frame format switching unit 323 data extraction unit 324 in first frame format second frame Format data Out section

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazuaki Takamune             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 5K033 AA07 BA15 CB01 CC01 DA02                       DA17 DB10 EA02                 5K034 AA06 EE03 HH63 NN22 TT01                 5K067 AA23 BB21 CC08 DD45 FF02                       HH23 HH26 HH28 KK15

Claims (11)

[Claims] 1. A first data receiving section for receiving encoded data assembled into a packet output by a transmitting terminal device, and a first data extracting section for extracting the encoded data from a packet according to a first protocol. A second data extraction unit that extracts the encoded data from a packet that follows a second protocol that is slower than the first protocol and has higher communication reliability, and the first data extraction unit or the second data extraction unit. A decoding unit that decodes the encoded data extracted by a data extraction unit, a data output unit that outputs the decoded data, a communication quality measurement unit that measures the communication quality of the encoded data, and the communication Either the first protocol or the second protocol is selected based on the control data for notifying the quality or the communication quality, and the selected protocol is passed. A reception terminal device, comprising: a control data generation unit that generates control data to be known; and a first data transmission unit that transmits the control data to the transmission terminal device. 2. A condition setting unit for inputting a condition is further provided, and the control data generation unit selects either the first protocol or the second protocol based on the condition and the communication quality. The receiving terminal device according to claim 1, wherein control data for notifying the selected protocol is generated. 3. The data includes a video signal and an audio signal, and in the second protocol, the protocol of the video signal is the same as that of the first protocol, but the protocol of the audio signal is different. Claim 1 characterized by the above.
Alternatively, the receiving terminal device according to claim 2. 4. A first data receiving section for receiving encoded data assembled into a packet output from a transmitting terminal device, and first data for extracting the encoded data from a packet having a first frame format. An extraction unit, a second data extraction unit that extracts the encoded data from a packet having a second frame format different from the first frame format, the first data extraction unit, or the second data extraction A data decoding unit for decoding the encoded data output by the unit, a data output unit for outputting the data decoded by the data decoding unit, and a communication quality measuring unit for measuring the communication quality of the encoded data. Control data for notifying the communication quality, or the first frame format or the second frame format based on the communication quality. A control data generation unit that selects one of the formats and generates control data that notifies the selected frame format; and a first data transmission unit that transmits the control data to the transmission terminal device. Receiving terminal device. 5. A condition setting unit for inputting a condition is further provided, and the control data generation unit sets either the first frame format or the second frame format based on the condition and the communication quality. The receiving terminal device according to claim 4, wherein control data for selecting and notifying the selected frame format is generated. 6. The receiving terminal device according to claim 4, wherein in the second frame format, error correction data is added to the first frame format. 7. The data includes a video signal and an audio signal, and the second frame format is occupied by the information amount of the audio signal in the entire information amount as compared with the first frame format. The receiving terminal device according to claim 4 or 5, wherein the ratio is large. 8. The receiving terminal device according to claim 1, wherein the first data receiving unit and the first data transmitting unit are wireless communication units. . 9. A transmission terminal device and claims 1 to 3.
The receiving terminal device according to claim 1, wherein the transmitting terminal device includes a second data receiving unit that receives the control data, a data input unit that inputs data, and the data. A data encoding unit that encodes to generate encoded data; a first packet assembling unit that assembles the encoded data into a packet that complies with the first protocol; and an encoded data that composes a packet that complies with the second protocol. A second packet assembling unit for assembling, and the code assembled into a packet according to the selected protocol by selecting the first protocol or the second protocol as a protocol of a packet to be transmitted based on the control data A second data transmission unit for transmitting the encoded data to the receiving terminal device, and a communication system. 10. A transmission terminal device, and the reception terminal device according to claim 4; wherein the transmission terminal device is a second device that receives the control data. A data receiving unit, a data input unit for inputting data, a data encoding unit for encoding the data to generate encoded data, and a first packet assembling unit for assembling the data into packets in the first frame format. A second packet assembly unit that assembles the data into packets in the second frame format, and a frame format of data to be transmitted based on the control data, which is the first frame format or the second frame format. Select a frame format and pre-code the encoded data assembled into packets in the selected frame format. Communication system receiver comprises a second data transmission unit, the to be transmitted to the terminal device, and wherein the. 11. The first data receiving section, the first data transmitting section, the second data receiving section and the second data transmitting section are wireless communication sections. Alternatively, the communication system according to claim 10.