JP2005303495A - Data transfer system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a data transfer system which lessens the reduction of throughput while ensuring a communication quality. <P>SOLUTION: The system inserts an error correction code 104 into data 103 of the packet in a radio frame, increases or decreases information stored as the error correcting code 104 in the data 103 according to communication conditions, thereby reinforcing the information quantity of the error correction code 104 to form a tough packet structure against communication errors, and applies an adaptive error resistance according to communication conditions, thus suppressing the deterioration of data throughput. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a data transfer system for efficiently performing data communication in a data communication such as a wireless network system existing in a home or a small office by compensating for the influence of a disturbance on a communication path or radio wave interference by signal processing.

  In recent years, with the spread of broadband communication, it has become possible to easily construct a network at home or in the office and exchange a large amount of data. In addition, wireless communication as a communication means that can easily handle data is rapidly spreading due to the low price and small size of devices. With the development of such communication technology, an environment for easily realizing information exchange by wireless communication from information data such as a personal computer to home image and sound data is being prepared.

  However, in wireless communication, the quality of data transfer depends on the communication environment, and the lack of information or the occurrence of errors on a desired radio wave due to an obstacle such as a wall or an external radio wave such as a microwave oven is remarkable. As one of data transfer systems that reliably transfer wireless communication data under such an environment, there is a wireless playback device described in (Patent Document 1). This apparatus will be described with reference to the block diagram of FIG.

  FIG. 6 is a block diagram of a conventional wireless playback apparatus.

  In FIG. 6, 626 is an operation unit, 625 is a coding processing means, 620 is a code transmission means, 619 is a transmission filter, 614 is a headphone, 612 is a reception antenna, 611 is a code reception means, 610 is a control code discrimination means, 604 Is a main body control means, 603 is a tape drive means, 605 is a tape, 606 is an amplifier, 607 is an A / D converter, 609 is a data transmission means, 613 is a transmission antenna, 615 is a reception filter, 618 is a reception data demodulation means, 623 Is a D / A converter, and 624 is a power amplifier. Reference numeral 602 denotes a remote control device, 601 denotes a reproduction device, 608 denotes transmission data rate conversion means, 621 denotes reception sensitivity detection means, 616 denotes a narrow band filter, 617 denotes low-speed reception data demodulation means, and 622 denotes a changeover switch.

  A conventional wireless playback apparatus has a separate configuration including a remote control apparatus 602 and a playback apparatus 601 and is wireless. The main feature of this wireless reproduction apparatus is that it includes a received data demodulating means 618 that demodulates a modulation signal at a normal speed of the received signal, and a low-speed received data demodulating means 617 that demodulates low-speed received data, In accordance with the input level of the received signal obtained by the means 618, the reception sensitivity detecting means 621 generates a transmission data rate switching signal and transmits it to the reproduction device 601. The reproduction device 601 discriminates the transmission data rate switching signal. The transmission data rate conversion means 608 switches the transmission data rate.

In this wireless reproduction apparatus, a normal modulation signal from the reproduction apparatus 601 is received from the code of the headphones 614 and demodulated by the reception data demodulation means 618 via the reception filter 615. The demodulated data is converted from digital data to an analog music signal by the D / A converter 623 via the changeover switch 622. The converted music signal is amplified by the power amplifier 624 and output from the headphones 614. In addition, the reception sensitivity detection unit 621 determines whether the intensity of the radio wave is appropriate from the signal demodulated by the reception data demodulation unit 618. When it is determined that the intensity of the radio wave is low, a reception signal is increased, and a switching signal for switching the transmission data rate is generated so that the sound output can be kept good. This switching signal is encoded by the encoding processing unit 625, modulated to a high frequency by the code transmission unit 620, and transmitted to the reproduction apparatus 601 from the code of the headphones 614 via the transmission filter 619. The reproduction apparatus 601 that has received the transmission data rate switching signal outputs a low-speed data modulation signal. A low-speed modulation signal is received from the code of the headphones 614, and demodulated by the low-speed reception data demodulating means 617 having high reception sensitivity via the reception filter 615 and the narrowband filter 616. The demodulated data is converted from digital data to an analog music signal by the D / A converter 623 via the changeover switch 622. The converted music signal is amplified by the power amplifier 624 and output from the headphones 614.

Thus, the conventional data transfer system realizes continuous data transfer by switching the transmission data rate according to the reception sensitivity.
JP-A-9-16979

  However, the conventional system is a system that performs communication with data that is more resistant to errors by improving the S / N of communication data by adaptively changing the communication rate according to the transmission environment. As a result, there is a drawback in that the data rate is lowered.

  In high-speed real-time communication of large volumes of image and audio data, visual and auditory sensory quality degradation due to a decrease in data rate is unpleasant, and a certain level of quality is maintained even in communication situations where errors occur. There is a need for a data transfer method that secures and realizes a system that minimizes a decrease in data throughput.

  SUMMARY An advantage of some aspects of the invention is that it provides a data transfer system in which a reduction in throughput is reduced while ensuring communication quality.

  In order to solve the above-mentioned problems, the present invention is characterized in that in the packet structure of a radio frame, a code for error correction is increased or decreased according to a communication state and stored in a data portion.

  According to the present invention, it is possible to generate a packet structure in which the information amount of a code for error correction that is resistant to communication errors is enhanced. As a result, the communication quality can be ensured without drastically reducing the data throughput by adding the error correction code having a small amount of information according to the communication status.

  The invention according to claim 1 of the present invention includes preamble data for synchronizing with a clock on the receiving side, a header portion indicating control information in a packet, a data portion for storing transmission data such as an image, sound, and file. A data transmission system having a packet structure of a frame composed of: a data communication system characterized in that an error correction code is stored in the data part by increasing / decreasing according to the communication state, and an error is stored in the data part By increasing and decreasing the correction code according to the communication state and storing the correction code, it is possible to generate a packet structure in which the information amount of the error correction code that is resistant to communication errors is enhanced. Thereby, error tolerance according to the communication status can be obtained, and a decrease in data throughput can be suppressed.

In the data transfer system according to claim 2 of the present invention, when data is analyzed on the receiver side, the amount of error information by error correction processing is monitored, and error monitor information on the reception status is included in the reception confirmation packet. Thus, a system for controlling the increase / decrease of the error correction code on the transmission side and flexibly strengthening the error correction code in accordance with the reception status is provided.

  In the data transfer system according to claim 3 of the present invention, the information length of the previous error correction code is inserted into the header portion in the packet, so that the error correction in the header portion is received when the packet is received on the receiving side. A system for performing error correction processing based on the information length of a code is provided.

  The data transfer system according to claim 4 of the present invention accumulates data in a packet generation buffer for a plurality of packets, and stores data and error correction information accommodated in the data portion in the packet in the horizontal direction and in the vertical direction. In addition, by arranging error correction generation information, even if packet loss or burst errors occur during reception, vertical and horizontal error correction processing is performed in the reception data buffer, so that information throughput is not reduced. A system for performing signal transmission is provided.

  In the data transfer system according to claim 5 of the present invention, an information array of a packet generation buffer for generating a packet on the transmission side is input to a random arrangement such as an M-sequence, and after error correction processing is performed on the reception side, By extracting data in the reverse order to the transmission side, a system is provided in which the strength is increased against bursty data errors such as radio interference.

  When analyzing data on the receiver side, the data transfer system according to claim 6 of the present invention monitors the reception order of packet data and the error status due to error correction processing, and the reception status signal is included in the reception confirmation packet. Is sent to the transmission side to control the increase / decrease of the error correction code on the transmission side and the amount of information in the depth direction of the packet generation buffer, and is adaptive to random errors and burst errors depending on the reception status A system that supports the enhancement of correction codes is provided.

  According to a seventh aspect of the present invention, there is provided the data transfer system according to the present invention, wherein the header information in the packet to be transmitted includes the information length of error correction information applied to the signal portion of the packet, the order information of the information string in the packet generation buffer, and M By inserting random generation algorithm coefficient information such as a sequence, a system is provided in which error correction processing is performed based on the error correction information length in the header when the packet is received on the receiving side.

  In the data transfer system according to claim 8 of the present invention, when error correction processing is performed on the receiving side, a flag indicating additional information is provided in the data detected by error detection, and information from the surrounding highly correlated information is reproduced. By interpolating, even in a system that does not frequently accept retransmission requests such as isochronous data transfer such as images and sounds, a system that suppresses quality degradation as much as possible is provided.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1A is a diagram showing a packet structure of a general radio frame, and FIG. 1B is a diagram showing a packet structure of a radio frame in the radio data transfer system according to the first embodiment of the present invention.

In FIG. 1A, reference numeral 101 denotes a signal unit that is necessary for detecting a frame signal that arrives at the preamble part and synchronizing with the clock on the receiving side. Reference numeral 102 denotes a header, which is control information in the packet, for example, the address of the transmitting station and the address of the receiving station, the sequence number of the frame
Contains information such as data length. A data portion 103 stores transmission data such as images, sounds, and files.

  On the other hand, the packet of the radio frame in Embodiment 1 of the present invention shown in FIG. 1B has an error correction code (hereinafter referred to as “below”) in the data portion 103 of the packet structure shown in FIG. The information amount 104 is increased or decreased according to the communication state to store the information amount corresponding to the correction capability, and the information amount of the error correction code 104 and the information amount of the data portion 103 are stored in the header portion. 102 is stored as a code length 105.

  Error correction code (Reed-Solomon code is mainly used as an error correction code in byte units.) When a 2-byte error correction code is inserted into information in the data section 103, a 1-byte correction capability Have Basically, 1 byte is corrected with 2 bytes (position and size). In the case of detection, 2 bytes can be detected with 2 bytes. However, since there is a limit of 255 in one byte, there is a case where erroneous detection is performed, so it is not preferable to use all the capabilities.

  Accordingly, since the error correction code 104 increases the correction capability with a small amount of information (1 correction or 2 detection with 2 bytes) as compared with the information amount of the data portion 103, the throughput load for improving the correction capability is considerably low.

  Also, the configuration can be made by generating the wireless packet in anticipation of the reduction of the packet gap and the amount of preamble information and the addition of padding information in anticipation of the maximum error correction amount.

  In response to the packet information on the transmitting side, the receiving side transmits an ACK packet notifying the transmitting side that the packet has been received. In this ACK packet, the number of error data calculated using an error correction code upon reception is transmitted to the embedded transmission side.

  On the sending side, the number of communication error data on the receiving side of the transmitted packet is accumulated as statistical data, and the amount of error correction code information (number of bytes: correction capability) of the packet to be sent is increased or decreased from the tendency of reception. Become.

  Hereinafter, the operations on the transmission side and the reception side will be described in detail with reference to FIG.

  FIG. 2 is an explanatory diagram showing a communication method using the wireless data transfer system according to Embodiment 1 of the present invention. In FIG. 2, 201 is a wireless data transmitter, and 202 is a wireless data receiver.

  As shown in FIG. 2, in the wireless data transfer system according to Embodiment 1 of the present invention, transmission data 203 is received by a receiver 202, and information in a packet header, specifically, an error correction code 104 such as Reed-Solomon. An error correction process is performed on the data in the packet based on the amount of information. At this time, the number of errors within the error correction range is counted, and the number of errors is accumulated. Then, the error number information is periodically inserted into a reception confirmation signal (ACK signal) 204 transmitted to the transmitter 201. As a result, the transmitter 201 receives the information on the number of errors and can check the error status, that is, the radio wave environment. The transmitter 201 controls the increase / decrease of the error correction capability, that is, the error correction code 104, based on the error number information.

In this way, since the wireless communication state on the receiver 202 side can be confirmed in real time on the transmitter 201 side, it corresponds to the error state using Reed-Solomon encoding processing that can perform error correction processing with a small amount of information. Error correction processing can be realized, and communication can be performed without reducing the data rate even in an unstable communication state that is a drawback of wireless communication. In addition, the increase or decrease in the information amount of the error correction code 104 can be suppressed to the information amount of the time interval that can be sufficiently absorbed in the gap period of the communication interval between the wireless packets. Further, the error correction code 104 on the transmission side can be controlled based on the reception sensitivity on the receiver 202 side, while strengthening the error occurrence state on the receiver 202 side as a parameter. It is also possible to enhance error tolerance by controlling the data transmission power on the transmitter 201 side together with the information amount of the error correction code 104.

(Embodiment 2)
FIG. 3A is a diagram showing a packet information array of the wireless data transfer system according to the second embodiment of the present invention.

  For the generation of radio packets on the transmission side, time-series data is randomly input in a random address system such as an M series, for example, in the X and Y directions as shown in FIG. Here, in the temporary buffer of FIG. 3A, the horizontal direction corresponds to the data portion of the wireless packet, and the vertical direction corresponds to the number of wireless packets. Further, the error correction code 104 has a configuration in which code data is allocated in the horizontal direction and the vertical direction in FIG. 3, respectively, and the resistance on the demodulation side with respect to random errors and burst errors is enhanced.

  FIG.3 (b) is a figure which shows the packet information arrangement | sequence (transmission side) of the radio | wireless data transfer system in Embodiment 2 of this invention.

  Information data sent in time series to the information storage unit of the error correction encoding temporary buffer is arranged in a random order, and error correction codes are inserted vertically and horizontally. Each row data of the temporary buffer is stored in the data portion 103 of the radio frame packet and the error correction code 104 and transmitted.

  FIG.3 (c) is a figure which shows the packet information arrangement | sequence (reception side) of the radio | wireless data transfer system in Embodiment 2 of this invention.

  On the receiving side, the data portion 103 of the wireless frame packet and the error correction code 104 are stored in an error correction temporary buffer similar to that on the transmitting side, and error correction is performed vertically and horizontally. By sequentially rearranging the data in the reverse order of the array arranged at random on the receiving side, the data in a burst form is scattered and arranged as random data, which concentrates errors as data passing to the application side. There is an effect to avoid.

  FIG. 4 is a flowchart showing control of error correction code 104 in transmission / reception of the wireless data transfer system according to the second embodiment of the present invention.

  First, data encoded on the transmission side and transmitted as a packet of a radio frame is received and demodulated on the reception side (STEP 1).

  On the receiving side, the error correction range (byte information amount) is read from the code length 105 of the packet data portion 103 written in the header portion 102 of the packet of the radio frame, and error correction processing of the packet of this radio frame is performed ( (Step 2).

  Subsequently, the number of errors in the error correction process is counted (STEP 3) and stored for each wireless packet (STEP 4).

  When a data reception confirmation signal is transmitted from the reception side to the transmission side, error number information is attached to the reception confirmation data (STPE 5) and transmitted. On the data transmission side, the information on the number of errors on the reception side is counted (STEP 6), and the radio wave communication status is grasped from the histogram distribution, and the information of the error correction code 104 comparable to the error correction capability in the next temporary buffer. The amount is determined and error correction coding is performed (STEP 7).

  In this way, by strengthening the error correction capability according to the communication status and the nature of the error by communicating the time-varying radio wave status by communicating the status of the number of errors on the receiving side with the reception confirmation information (ACK signal) Error correction code arrangement corresponding to (random, burst) can be performed.

(Embodiment 3)
FIG. 5 is a diagram showing a packet information array of the wireless data transfer system according to the third embodiment of the present invention.

  In FIG. 5, after the packet data received on the receiving side is arranged in an error correction buffer and subjected to error correction processing, there is an error in the data corresponding to the error position with respect to the data that could not be error corrected. Is inserted into the information arranged in time series. Here, with respect to data for which an error flag is set, in the case of voice or image data, data interpolation processing is performed based on peripheral data having high correlation, and the data is replaced with data that is not conspicuous for human senses.

  In this way, even for data that could not be corrected even if the vertical and horizontal double error correction processing was performed, normal data in the surrounding area was obtained using random array of burst data by random array and error data flag. Therefore, even in real-time communication with limited retransmission requests such as images and sounds, data quality can be easily handled by interpolation processing without losing human sense.

  Regarding the error correction processing and interpolation processing shown in the first, second, and third embodiments of the present invention, interpolation processing is performed for data that cannot be corrected in real-time communication such as images and sounds that are restricted in communication time. It is easy to replace data that is not conspicuous in human sense. Also, in data communication and video / audio, the amount of error correction code information on the receiving side is monitored for two types of data with different properties that affect information errors such as compressed data. Therefore, it is possible to grasp the addition of the error resistance code on the transmission side.

  As described above, the data transfer system of the present invention is a drawback of a convenient data communication method that is rich in the portability of wireless communication, based on error information on the receiving side, against a radio wave environment that changes from moment to moment, By periodically inserting error monitor information into the reception confirmation information (ACK signal), it is possible to enhance the error correction capability according to the error occurrence status on the transmission side in real time, so build a home network On the other hand, with respect to real-time communication of images and sounds, while maintaining a reduction in data throughput, quality degradation due to errors can be minimized and stable communication can be ensured. In addition, regarding a file that is fatal to the occurrence of an error, such as a PC file, a reduction in data throughput due to retransmission can be eliminated as much as possible, and stable data communication can be performed.

Furthermore, the present invention relates to a wireless data transfer system. However, the present invention is not limited to package media (such as CDs) such as images and sounds in the home, but is interactive for real-time communication such as digital broadcasting and telephones. Real-time communication may be used. Also, error correction is not limited to correction-only processing, and it may be mixed with error detection, or detection by vertical and horizontal error correction, mixed correction or correction in one direction, and mixed detection. Needless to say, it does not prescribe the number of correction and detection information.

  The data transfer system of the present invention is useful not only for mobile phones, wireless LAN electronic devices, and home data distribution devices (STB), but also for systems that wirelessly distribute images, voice, data, telephones, and the like.

(A) The figure which shows the packet structure of a general radio | wireless frame, (b) The figure which shows the packet structure of the radio | wireless frame of the radio | wireless data transfer system in Embodiment 1 of this invention. Explanatory drawing which shows the communication method by the wireless data transfer system in Embodiment 1 of this invention (A) The figure which shows the packet information arrangement | sequence of the radio | wireless data transfer system in Embodiment 2 of this invention, (b) The figure which shows the packet information arrangement | sequence (transmission side) of the radio | wireless data transfer system in Embodiment 2 of this invention, (C) The figure which shows the packet information arrangement | sequence (reception side) of the radio | wireless data transfer system in Embodiment 2 of this invention. Control flowchart of error correction code 104 in transmission / reception of the wireless data transfer system according to the second embodiment of the present invention. The figure which shows the packet information arrangement | sequence of the radio | wireless data transfer system in Embodiment 3 of this invention. Block diagram of a conventional wireless playback device

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Preamble part 102 Header part 103 Data part 104 Error correction code 105 Code length 201 Transmitter 202 Receiver 203 Transmission data 204 Reception confirmation signal 601 Reproducing apparatus 602 Remote control apparatus 603 Tape drive means 604 Main body control means 605 Tape 606 Amplifier 607 A / D converter 608 Transmission data rate conversion means 609 Data transmission means 610 Control code discrimination means 611 Code reception means 612 Reception antenna 613 Transmission antenna 614 Headphone 615 Reception filter 616 Narrow band filter 617 Low-speed reception data demodulation means 618 Reception data demodulation means 619 Transmission Filter 620 Code transmission means 621 Reception sensitivity detection means 622 Changeover switch 623 D / A converter 624 Power amplifier 6 5 coding processing unit 626 operation unit

Claims (8)

It has a packet structure of a frame composed of a preamble part for synchronizing with the clock on the receiving side, a header part indicating control information in the packet, a data part for storing transmission data such as an image, sound, and file. A data transfer system, wherein an error correction code is increased or decreased according to a communication state and stored in the data portion. 2. The data transfer system according to claim 1, wherein when analyzing data on the receiver side, the error information amount by error correction processing is monitored, and error monitor information on the reception status is sent to the transmission side in the reception confirmation packet. A data transfer system characterized by controlling increase / decrease of error correction code information on the transmission side and flexibly responding to the enhancement of error correction code according to the reception status. 3. The data transfer system according to claim 1, wherein the packet is received on the receiving side by inserting an information length of an error correction code applied to a data portion of the packet into a header portion in the packet. In this case, an error correction process is performed based on the information length of the error correction code in the header. In the process of generating a signal packet to be transmitted, data is accumulated in a packet generation buffer for a plurality of packets, the data and error correction information accommodated in the data portion in the packet in the horizontal direction, and error correction information in the vertical direction as well. By arranging the generated information, even if packet loss or burst errors occur during reception, vertical and horizontal error correction processing is performed in the reception data buffer, realizing signal transmission that does not reduce information throughput A data transfer system. 5. The data transfer system according to claim 4, wherein an information array of a packet generation buffer for generating a packet on a transmission side is input to a random position by an algorithm for generating a random value such as an M series, and received. After performing error correction processing on the side, the data is rearranged in the reverse process of the transmission side to convert burst data errors such as radio interference into a random array, and interpolation processing with surrounding data during data reproduction A data transfer system characterized by increasing the accuracy of data restoration. 6. The data transfer system according to claim 4, wherein when the data is analyzed on the receiver side, the reception order of the packet data and the error status by the error correction process are monitored, and the reception status signal is displayed in the reception confirmation packet. By sending to the transmitting side, the error correction code increase / decrease on the transmitting side and the amount of information in the depth direction of the packet generation buffer are controlled, and adaptive to random errors and burst-like errors according to the reception status A data transfer system characterized in that the correction code is strengthened flexibly on the transmission side. The data transfer system according to any one of claims 4 to 6, wherein the header information in the packet to be transmitted includes the information length of an error correction code applied to the signal portion of the packet and the order of the information string in the packet generation buffer. By inserting information and random generation algorithm coefficient information such as an M-sequence, when the packet is received on the receiving side, an error correction process is performed based on the information length of the error correction code in the header Data transfer system. The data transfer system according to any one of claims 1 to 7, wherein when performing error correction processing on the receiving side, a flag indicating additional information is provided in data detected by error detection, and peripheral correlation is high during reproduction. A data transfer system characterized by minimizing quality deterioration of isochronous data transfer such as images and sounds by interpolating from information.

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