JP2006254266A - Data transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a data transmission system which transmits an image data having high bit rate, by dividing it through a plurality of radio transmission lines (channel) and transmits and restores the divided data normally, by monitoring a communication state each channel. <P>SOLUTION: The data transmission system for transmitting digital data via the plural radio transmission lines is provided with a communication state monitoring means to monitor the communication state in the plural radio transmission lines, and transmits the divided data to be transmitted by its specific radio transmission line by other radio transmission line, when it is decided that the divided data are not transmitted normally by the communication state monitoring means in the specific radio transmission line. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a data transmission system capable of transmitting high bit rate video information and the like via a wireless transmission line, and more particularly, a home for transmitting packetized data in the MPEG2-transport stream format using a wireless LAN. Related to network system.

  In recent years, DVD / HDD recorders and personal computers equipped with a PVR (Personal Video Recorder) function have been widely used, and video assets that individuals can view at home have also increased. In addition, it is required to enjoy contents such as video information stored on a DVD / HDD recorder or a personal computer at a place where the user wants to view the content, and a client such as a television or a personal computer using a home network. Technologies that enable output to equipment have been proposed. As a technique for transmitting a large amount of data such as video data and audio data at high speed and in real time, for example, IEEE 1394 is adopted as a connection interface for digital television, digital video, and the like.

  Recently, in order to simplify the connection between devices, a DVD / HDD recorder, a personal computer, a liquid crystal monitor, and the like can be connected using a wireless LAN. As a typical technique of this wireless LAN, there is IEEE 802.11 standardized by IEEE, and the one using the 2.4 GHz band is the mainstream. The 2.4 GHz band is called an ISM (Industrial, Scientific and Medical) band, and is a frequency band used for industrial, medical, and household microwave ovens. In Japan, 2.400-2.497 GHz is a wireless LAN. Assigned to.

  By the way, in order to use a wireless LAN as a transmission medium for AV data including video data and audio data, a technology for transmitting high-definition video information at a high bit rate with high quality is required. For example, video data requires a transmission rate of 2 to 30 Mbps per channel, and audio data requires a transmission rate of 64 kbps to 1.5 Mbps per channel. On the other hand, a few Mbps is sufficient for the Internet only for Web access, but a transmission speed of several tens of Mbps is required for content distribution or the like.

As described above, when transmitting high bit rate video data or the like using a single wireless transmission path (channel), an occupied frequency bandwidth capable of transmitting the bit rate is required. There is a problem that video data having a bit rate exceeding the transmission capacity of the transmission path cannot be transmitted. Therefore, by dividing the high bit rate video data and transmitting it through multiple transmission channels (channels), it is possible to transmit and receive high bit rate video data even if the frequency bandwidth of the transmission channel is narrow. Transmission systems have been proposed (for example, Patent Documents 1 and 2).
JP 2002-344965 A JP2002-77088

  However, in the techniques disclosed in Patent Documents 1 and 2 described above, high bit rate video data is divided and transmitted through a plurality of transmission lines. This causes a problem that the original high bit rate video data cannot be restored. For example, the transmission speed may be different for each of the plurality of transmission paths, or the transmission channel may not be usable in wireless communication. In this case, the divided data can be restored in order on the receiving device side. Disappear.

  The present invention is a data transmission system that divides high bit rate video data and transmits it through a plurality of wireless transmission paths (channels), and normally transmits the divided data by monitoring the communication state of each channel. It is an object of the present invention to provide a data transmission system that can be restored.

  The present invention has been made to solve the above-mentioned problems, and is a data supply means for supplying digital data including video data or audio data, and a data dividing means for dividing the digital data supplied by the data supply means. And a data transmitting means for transmitting the divided data through a plurality of transmission paths, a data receiving means for receiving the divided data transmitted via each transmission path, and the received divided data. In the data transmission system configured to transmit digital data via the plurality of wireless transmission paths, the transmitting device includes the plurality of data combining means for restoring the original data. A communication state monitoring unit for monitoring a communication state in a wireless transmission path, wherein the data transmission unit is connected to the communication state monitoring unit; If the transmission of the successfully divided data in the constant of the wireless transmission path is determined not performed, and transmits the divided data to be transmitted by another wireless transmission path by the particular radio channel.

  In addition, the data transmission unit is configured to determine whether or not the communication state has been recovered when the communication state monitoring unit determines that the divided data is not normally transmitted on the specific wireless transmission path. The test data is transmitted through the specific wireless transmission path, and after the test data can be received by the data receiving means corresponding to the specific wireless transmission path, the transmission of the divided data is resumed.

  At this time, even if the low bit rate test data can be transmitted, it is not always possible to transmit the high bit rate divided data to be transmitted. Therefore, the test data is the bit of the divided data originally transmitted. The bit rate should be equal to or higher than the rate.

  In the data transmission system capable of transmitting digital data via two wireless transmission paths, the communication state monitoring means continuously receives a reception confirmation response signal for the divided data transmitted from one of the wireless transmission paths for a predetermined number or more. When received, it is determined that the divided data is not normally transmitted in the other wireless transmission path.

  Further, when the digital data is in the MPEG transport stream format, the data dividing means divides the MPEG transport stream supplied by the data supplying means in units of packets, and the data combining means receives the received division. The original MPEG transport stream is restored by combining the packets.

  According to the present invention, communication state monitoring means for monitoring communication states in a plurality of wireless transmission paths is provided on the transmitting device side, and the data transmission means is configured to normally divide data in a specific wireless transmission path by the communication state monitoring means. Since it is determined that the divided data to be transmitted by the specific wireless transmission path is transmitted by another wireless transmission path when it is determined that the transmission of the high-bit-rate digital data (for example, MPEG transport) Stream) can be distributed and transmitted to a plurality of wireless transmission lines with narrow frequency bandwidths, and it is possible to avoid the fact that the divided data cannot be partially received and the original digital data cannot be restored. . Thus, the viewer can efficiently transmit high bit rate video data using the wireless LAN, and can enjoy high quality video without interruption even at a distant place.

  The data transmission means is test data for determining whether or not the communication state has been recovered when it is determined by the communication state monitoring means that the divided data is not normally transmitted on the specific wireless transmission path. Is transmitted through the specific wireless transmission path, and after the test data can be received by the data receiving means corresponding to the specific wireless transmission path, the transmission of the divided data is resumed. Possible wireless transmission paths can be used effectively.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a home network system according to the present embodiment. In the following description, an example in which digital data (for example, an MPEG transport stream) is wirelessly transmitted using two channels will be described. However, the present invention is not limited to this, and three or more channels are used. Also good.

  A home network system 100 according to the present embodiment includes a content providing device 10 that provides content (analog data or digital data) including video data and audio data, a transmission device 20, a reception device 30, a liquid crystal monitor, a speaker, and the like. Output device 40. Here, the content providing apparatus 10 corresponds to, for example, a DVD / HDD recorder, a video tape recorder, a receiver for analog television broadcasting or digital television broadcasting, and is usually a display device such as a liquid crystal monitor or a sound such as a speaker. AV equipment that can be connected directly to an output device to output video and audio.

  In the home network system 100, for example, the content providing device 10 and the transmission device 20, and the reception device 30 and the output device 40 are connected by a cable conforming to IEEE 1394, and the transmission device 20 and the reception device 30 are wireless based on IEEE 802.11b. Data transmission is performed using a LAN.

  The content providing apparatus 10 has an AV data generation unit (not shown), reads content (video data, audio data) from a recording medium such as a DVD, a video cassette tape, and a hard disk, or performs digital television broadcasting or analog television broadcasting. , And the content or television broadcast is converted into a predetermined format and output as AV data. The AV data output from the content providing apparatus 10 is analog data or digital data depending on the type of media and the function of the content providing apparatus.

  FIG. 2 is a schematic configuration diagram of the transmission device 20. As shown in FIG. 2, the transmission apparatus 20 includes an A / D conversion unit 21, an MPEG encoder 22, an MPEG division unit 23, buffer circuits 24a and 24b, MAC / PHY units 25a and 25b, and a high frequency amplification unit. 26a and 26b, antennas 27a and 27b, and a control unit 28, and receives AV data supplied from the content providing apparatus 10 in the MPEG2-compliant transport stream (hereinafter abbreviated as MPEG2-TS) format. To device 30.

  The A / D converter 21 converts analog AV data transmitted from the content providing apparatus 10 into digital data. The MPEG encoder 22 compresses and encodes the digital AV data supplied from the A / D converter 21 according to the MPEG2 system, and multiplexes these compressed data to generate MPEG2 TS.

  Here, MPEG2-TS is composed of a series of 188-byte fixed-length transport stream packets (hereinafter abbreviated as TS packets) as shown in FIG. One TS packet is composed of a 4-byte packet header and a 184-byte payload. The packet header includes a synchronization byte and a packet ID for identifying the head of the packet. Describes video, audio, data, and the like.

  If the AV data supplied from the content providing apparatus 10 is already in the MPEG2-TS format, the A / D conversion unit 21 and the MPEG encoder 22 are not used.

  The control unit 28 includes a CPU (not shown), a RAM, and a ROM. Various control programs are stored in the ROM, and the CPU operates according to the control programs in the ROM while using the RAM as a work area. For example, the control unit 28 detects the synchronization byte in the MPEG2-TS packet header supplied from the MPEG encoder 22 and generates a packet synchronization signal synchronized with the transmission packet, and also divides the generated packet synchronization signal into MPEG The signal is supplied to the unit 23 and the operation of the MPEG dividing unit 23 is controlled.

  Based on the packet synchronization signal supplied from the control unit 28, the MPEG dividing unit 23 divides one MPEG2-TS at the boundary of the transmission packet, and sequentially distributes it to the subsequent buffer circuits 24a and 24b in units of packets. Specifically, the supplied MPEG2-TS is divided for each packet (PACK # 1, PACK # 2,...), And PACK # 1, # 3, # 5,. , And PACKs # 2, # 4, # 6,... Are output to the buffer circuit 24b.

  The buffer circuits 24a and 24b sequentially store the divided packets supplied from the MPEG dividing unit 23. The MAC / PHY units 25a and 25b perform modulation / demodulation processing on the divided packets output from the buffer circuits 24a and 24b according to protocol processing and a predetermined modulation method (for example, DSSS modulation method).

  The high frequency amplifiers 26a and 26b amplify the RF signal by high frequency and transmit the amplified RF signal to the receiving device 30 via the transmitting antennas 27a and 27b. For example, the RF signal is transmitted through wireless transmission paths of different frequency bands (for example, center frequencies 2.412 GHz and 2.484 GHz).

  In the transmission apparatus 20 of the present embodiment, the MPEG2-TS is divided in units of packets, and in principle, PACK # 1, PACK # 3, PACK # are transmitted by the first transmission path (RF_ # 1) transmitted from the transmission antenna 26a. .., And PACK # 2, PACK # 4, PACK # 6,... Are transmitted through the second transmission path (RF_ # 2) transmitted from the transmission antenna 26b. However, if the communication state deteriorates due to a decrease in the bandwidth that can be transmitted on one of the first transmission path or the second transmission path and the divided packet cannot be transmitted normally, the other transmission that can be normally transmitted Transmission / reception is performed via a transmission line.

  FIG. 3 is a schematic configuration diagram of the receiving device 30. As shown in FIG. 3, the receiving device 30 includes receiving antennas 31a and 31b, high-frequency amplifiers (RF) 32a and 32b, MAC / PHY units 33a and 33b, buffer circuits 34a and 34b, and an MPEG coupling unit 35. An MPEG decoder 36, a D / A conversion unit 37, and a control unit 38, and receives the divided packet transmitted from the transmission device 20.

  The receiving antennas 31a and 31b receive RF signals transmitted from the transmitting device 20 via wireless transmission paths of different frequency bands, and supply the received RF signals to the corresponding high frequency amplifying units 32a and 32b.

  The high frequency amplifying units 32a and 32b amplify the RF signal received by the receiving antennas 31a and 31b at a high frequency and supply the amplified RF signals to the MAC / PHY units 33a and 33b.

  The MAC / PHY units 33a and 33b perform protocol processing and modulation / demodulation processing on the divided packets supplied from the high frequency amplification units 32 and 32b according to a protocol processing and a predetermined modulation method. The buffer circuits 34a and 34b sequentially store the divided packets supplied from the MAC / PHY units 33a and 33b.

  The control unit 38 includes a CPU, a RAM, and a ROM (not shown). Various control programs are stored in the ROM, and the CPU operates according to the control programs in the ROM while using the RAM as a work area. For example, the control unit 38 detects the synchronization byte in the packet header included in the divided packet supplied from the MAC / PHY units 33a and 33b, generates a packet synchronization signal synchronized with the transmission packet, and generates the generated packet. The synchronization signal is supplied to the MPEG coupling unit 35 and the operation of the MPEG coupling unit 35 is controlled.

  Based on the packet synchronization signal supplied from the control unit 28, the MPEG combining unit 35 reads the divided packets from the buffer circuits 34a and 34b, combines the plurality of divided packets, and restores and outputs the original MPEG2-TS.

  The MPEG decoder 36 decompresses and decodes the MPEG2-TS supplied from the MPEG combining unit 35 to generate digital AV data. The D / A converter 37 converts the digital AV data supplied from the MPEG decoder 36 into analog AV data and outputs the analog AV data to the output device 40.

  If the output device 40 can reproduce AV data in the MPEG2-TS format, the MPEG decoder 36 and the D / A converter 37 are not used.

  In the receiving device 30 of the present embodiment, PACK # 1, PACK # 3, PACK # 5,... Transmitted by the first transmission path (RF_ # 1), and transmission by the second transmission path (RF_ # 2). The received PACK # 2, PACK # 4, PACK # 6,... Are received by corresponding receiving means, and these are combined to restore the original MPEG2-TS.

  Next, data transmission control processing in the transmission device 20 will be described in detail with reference to the flowchart of FIG. In this data transmission control process, a control program is executed by the control unit 28 of the transmission device 20, and each circuit is controlled according to this.

  In the present embodiment, when MPEG2-TS cannot be normally transmitted due to a decrease in bandwidth that can be transmitted in one of the first transmission line and the second transmission line, the other transmission line that can be normally transmitted. The transmission / reception is performed by Specifically, for the transmission path on the side that cannot normally transmit data, the side that can normally transmit data until the communication mode is changed from the normal mode to the return mode and then recovered from the return mode to the normal mode The data is transmitted from the transmission line.

  It is assumed that the transmission path on the side that can normally transmit data is RF_OK, and the transmission path on the side that cannot transmit data normally is RF_NG.

  First, the MPEG dividing unit 23 divides one MPEG2-TS at a transmission packet boundary. Then, the PACKs # 1, # 3, # 5,... Of the divided packets are output to the buffer circuit 24a to the subsequent buffer circuits 24a, 24b, and the PACKs # 2, # 4, # 6,. Output (step S101). Next, PACK # 1 is transmitted from the first transmission path (RF_ # 1), and PACK # 2 is transmitted from the second transmission path (RF_ # 2) (step S102).

  Next, it is determined whether or not an ACK (response confirmation) is returned when the transmitted data can be normally received by the receiving device 30 (step S103). Here, data can be normally transmitted and received on the transmission path that has received ACK (RF_OK).

  Next, when it is determined in step S103 that ACK has been received, it is determined whether the communication mode of the transmission path (RF_OK) on the ACK reception side is the normal mode or the return mode (step S104). Here, in the initial state, the communication mode of any transmission path is the normal mode. However, in step S109 described later, the communication mode may be shifted to the return mode. Since the normal mode and the return mode may occur, control is performed according to the communication mode of the transmission path (RF_OK) on the ACK reception side.

  If it is determined in step S104 that the RF_OK is in the normal mode, it is determined whether or not ACK has been continuously received over a predetermined number of times on the same transmission path (step S105). That is, when data transmission / reception is not normally performed on one transmission path, ACK is continuously received only on the other transmission path, so that the communication state on each transmission path is monitored. (Communication state monitoring means).

  Here, the predetermined number of times is set within a range in which AV data can be reproduced without interruption by the receiving device 30. That is, it is desirable to set within the range in which the next MPEG2-TS combination, MPEG decoding, and D / A conversion can be completed before there is no AV data to be transmitted from the receiving device 30 to the output device 40. Is determined based on the buffer capacity and the like. In this embodiment, in order to simplify the explanation, when ACK is received twice or more continuously on the same transmission path, it is determined that data cannot be normally transmitted on the other transmission path. To do.

  If it is determined in step S105 that ACK has not been received continuously twice or more on the same transmission path, that is, ACK has been received alternately on the first transmission path and the second transmission path, the buffer 24a 24b, the next PACK (PACK # 3 if ACK is received on the first transmission path, PACK # 4 if ACK is received on the second transmission path) is read and transmitted (step S106).

  On the other hand, if it is determined in step S105 that ACK has been received continuously twice or more on the same transmission path, the process proceeds to step S108. For example, when ACKs for the transmission of PACK # 1 and PACK # 3 are continuously received on the first transmission path, transmission to PACK # 2 is not normally performed on the second transmission path (the second transmission path). The transmission path is determined to be RF_NG), and the process proceeds to step S108. In step S108, it is determined whether the communication mode of the transmission line (RF_NG) on the side where data cannot be normally transmitted / received is the normal mode or the return mode.

  If it is determined in step S108 that the RF_NG communication mode is the normal mode, the communication mode is changed from the normal mode to the return mode (step S109), and test data is transmitted from the RF_NG (step S110). Here, the test data may be data for determining whether or not the RF_NG communication state has been recovered, and the data format is not particularly limited. However, it is desirable that the bit rate is equal to or higher than that of the actually transmitted divided packet in order to use as a guideline whether or not the MPEG2-TS divided packet can be normally transmitted.

  On the other hand, from RF_OK, the PACK # that has been transmitted on the first transmission path is compared with the PACK # that has been transmitted on the second transmission path, and a PACK with a lower order is transmitted (step S111). For example, when ACKs for PACK # 1 and PACK # 3 transmitted from the first transmission path are continuously received and it is determined that transmission to PACK # 2 is not normally performed on the second transmission path, PACK # 2 is read from the buffer circuit 24b and transmitted from RF_OK (RF_ # 1).

  If it is determined in step S108 that the RF_NG communication mode is the return mode, the RF_NG communication state is not recovered, and the test data is transmitted from the RF_NG without changing the communication mode (step S108). S112).

  On the other hand, the PACK with the youngest order is transmitted from RF_OK (step S113). For example, after receiving ACK for PACK # 1 and PACK # 3 transmitted from the first transmission path, PACK # 2 is transmitted from the first transmission path (step S111), and ACK for PACK # 2 is received. In this case, since it can be determined that the test data has not been normally transmitted on the second transmission line, PACK # 4 is read from the buffer circuit 24b and transmitted from RF_OK (RF_ # 1).

  Also, when test data is transmitted from RF_NG and ACK is received, it is determined that the communication mode of the transmission path (RF_OK) that has received ACK is the return mode (step S104). While shifting to the normal mode (step S107), the next PACK is read from the buffers 24a and 24b and transmitted (step S106). For example, if the first transmission path is transmitted from the first transmission path to PACK # 4 before the second transmission path recovers from the return mode, the next PACK # 6 is transmitted from the second transmission path in step S106. It becomes.

  As described above, in the present embodiment, the transmission device 20 monitors the communication state in the two wireless transmission paths, and the divided packet is normally transmitted in the specific wireless transmission path (for example, the second transmission path). If it is determined that the divided packet to be transmitted by the specific wireless transmission path is transmitted by another wireless transmission path (first transmission path), the high bit rate MPEG2-TS is transmitted. In addition to being able to distribute and transmit to a plurality of wireless transmission paths having a narrow frequency bandwidth, it is possible to avoid that the receiving device 30 cannot partially receive the divided data and cannot restore the original digital data. Accordingly, the viewer can efficiently transmit video data and the like using a wireless LAN, and can enjoy high-quality content without interruption even at a distant place.

  In addition, when it is determined that the divided packet is not normally transmitted in the specific wireless transmission path, test data for determining whether or not the communication state is recovered is transmitted through the specific wireless transmission path. At the same time, after the test data can be received by the data receiving means corresponding to the specific wireless transmission path, the transmission of the divided packet is resumed, so that the wireless transmission path that can be transmitted is used effectively. Can do.

  As mentioned above, although the invention made by this inventor was concretely demonstrated based on embodiment, this invention is not limited to the said embodiment, It can change in the range which does not deviate from the summary.

  For example, in the above embodiment, MPEG2-TS is divided and transmitted in packet units, but the original data is not limited to MPEG2-TS, and can be applied to transmission of other digital data.

  Moreover, although the said embodiment demonstrated the wireless LAN using the 2.4 GHz band prescribed | regulated by IEEE802.11b, the other wireless transmission technique can also be utilized. For example, there is a 5.2 GHz band wireless LAN defined by IEEE802.11a, a 2.4 GHz band wireless LAN defined by IEEE802.11g, an optical wireless LAN, and the like. Note that Bluetooth is not suitable for data transmission at a high bit rate such as video data because the transmission speed is lower than that of the wireless LAN (about 1 Mbps).

  In the above-described embodiment, the transmission device 20 and the content providing device 10 may be integrally configured as data transmission means, or the reception device 30 and the output device 40 may be integrally configured as data reception means. . For example, a DVD / HDD recorder having a wireless communication function can be used as data transmission means, and a television receiver having a wireless communication function can be used as data reception means.

It is a schematic block diagram of the home network system of this embodiment. 2 is a schematic configuration diagram of a transmission device 20. FIG. 2 is a schematic configuration diagram of a receiving device 30. FIG. It is a flowchart which shows a data transmission control process. It is explanatory drawing which shows the structure of MPEG2-TS.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Content provision apparatus 20 Transmission apparatus 21 A / D conversion part 22 MPEG encoder 23 MPEG division | segmentation part 24a, b Buffer (transmission apparatus side)
25a, b MAC / PHY section 26a, b High frequency amplification section 27a, b Transmitting antenna 28 Control section (transmitting device side, communication state monitoring means)
30 receiving device 31a, b receiving antenna 32a, b high frequency amplifying unit 33a, b MAC / PHY unit 34a, b buffer (receiving device side)
35 MPEG Coupling Unit 36 MPEG Decoder 37 D / A Conversion Unit 40 Output Device 100 Home Network System

Claims (16)

MPEG data supply means for supplying an MPEG transport stream including video data or audio data; data division means for dividing the MPEG transport stream supplied by the data supply means in units of packets; A data transmission means for transmitting via a wireless transmission path;
A receiving device having data receiving means for receiving divided packets transmitted via each transmission path and data combining means for restoring the original MPEG transport stream by combining the received divided packets In a data transmission system capable of transmitting digital data in the MPEG transport stream format via the two wireless transmission paths,
The transmitter is
Comprising communication state monitoring means for monitoring communication states in two wireless transmission paths;
When the communication status monitoring means continuously receives a reception confirmation response signal for a divided packet transmitted from one wireless transmission path for a predetermined number or more, the divided packet is not normally transmitted on the other wireless transmission path. And
When the communication state monitoring unit determines that the divided packet is not normally transmitted on the specific wireless transmission path, the data transmission unit transmits the divided packet to be transmitted on the specific wireless transmission path to another A data transmission system characterized by transmitting test data having a bit rate equal to or higher than the bit rate of the originally transmitted divided packet through the specific wireless transmission path. Data supply means for supplying digital data including video data or audio data, data division means for dividing the digital data supplied by the data supply means, and data transmission means for transmitting the divided data through a plurality of wireless transmission paths A transmitter having
A data receiving means for receiving the divided data transmitted via each transmission path, and a data combining means for combining the received divided data and restoring the original data, and a receiving device comprising the above, In a data transmission system capable of transmitting digital data via a plurality of wireless transmission paths,
The transmitter is
Comprising communication state monitoring means for monitoring communication states in the plurality of wireless transmission paths,
When the communication state monitoring unit determines that the divided data is not normally transmitted on the specific wireless transmission line, the data transmission unit transmits the divided data to be transmitted on the specific wireless transmission line to another data transmission unit. A data transmission system, wherein transmission is performed through a wireless transmission path. The data transmitting means is test data for determining whether or not the communication state has been recovered when it is determined by the communication state monitoring means that the divided data is not normally transmitted on a specific wireless transmission line. Is transmitted by the specific wireless transmission path,
3. The data transmission system according to claim 2, wherein after the test data can be received by the data receiving unit corresponding to the specific wireless transmission path, transmission of the divided data is resumed.   4. The data transmission system according to claim 2, wherein the test data has a bit rate equal to or higher than a bit rate of divided data originally transmitted. In a data transmission system capable of transmitting digital data via two wireless transmission paths,
When the communication status monitoring means continuously receives a reception confirmation response signal for the divided data transmitted from one of the wireless transmission paths, the divided data is not normally transmitted on the other wireless transmission path. The data transmission system according to claim 2, wherein the data transmission system is determined. The digital data is in the MPEG transport stream format,
The data dividing means divides the MPEG transport stream supplied by the data supply means in units of packets,
6. The data transmission system according to claim 2, wherein the data combining means combines the received divided packets to restore the original MPEG transport stream. On the data transmission side, digital data including video data or audio data is input, and the input data is divided and transmitted through a plurality of wireless transmission paths,
On the data receiving side, in the data transmission system that receives the divided data transmitted via each transmission path and combines the received divided data to restore the original data,
Monitor the communication status in the plurality of wireless transmission paths,
As a result of the above monitoring, when it is determined that the divided data is not normally transmitted on the specific wireless transmission path, the divided data to be transmitted on the specific wireless transmission path is transmitted on the other wireless transmission path. A data transmission method characterized by the above. As a result of the monitoring, when it is determined that the divided data is not normally transmitted in the specific wireless transmission path, test data for determining whether or not the communication state has been restored is the specific wireless transmission path. And send by
8. The data transmission method according to claim 7, wherein transmission of the divided data is resumed after the test data can be transmitted on the specific wireless transmission path.   9. The data transmission method according to claim 7, wherein the test data has a bit rate equal to or higher than a bit rate of divided data originally transmitted. In a data transmission method capable of transmitting digital data via two wireless transmission paths,
When reception confirmation response signals for divided data transmitted from one wireless transmission path are continuously received by a predetermined number or more, it is determined that the divided data is not normally transmitted in the other wireless transmission path. A data transmission method according to any one of claims 7 to 9. The digital data is in the MPEG transport stream format,
On the data transmission side, the input MPEG transport stream is divided into packets,
11. The data transmission method according to claim 7, wherein the original MPEG transport stream is restored on the data receiving side by combining the received divided packets. Data supply means for supplying digital data including video data or audio data; data division means for dividing the digital data supplied by the data supply means; data transmission means for transmitting the divided data through a plurality of transmission paths; A transmission device comprising:
Comprising communication state monitoring means for monitoring communication states in the plurality of wireless transmission paths,
When the communication state monitoring unit determines that the divided data is not normally transmitted on the specific wireless transmission line, the data transmission unit transmits the divided data to be transmitted on the specific wireless transmission line to another data transmission unit. A transmission apparatus characterized by transmitting via a wireless transmission path. The data transmitting means is test data for determining whether or not the communication state has been recovered when it is determined by the communication state monitoring means that the divided data is not normally transmitted on a specific wireless transmission line. Is transmitted by the specific wireless transmission path,
13. The transmission apparatus according to claim 12, wherein transmission of the divided data is resumed after the test data can be transmitted through the specific wireless transmission path.   The transmission device according to claim 12 or 13, wherein the test data has a bit rate equal to or higher than a bit rate of divided data originally transmitted. The data transmitting means can transmit digital data via two wireless transmission paths,
When the communication status monitoring means continuously receives a reception confirmation response signal for the divided data transmitted from one of the wireless transmission paths, the divided data is not normally transmitted on the other wireless transmission path. The transmitter according to claim 12, wherein the transmitter is determined. The digital data is in the MPEG transport stream format,
16. The transmission apparatus according to claim 12, wherein the data dividing unit divides the MPEG transport stream supplied from the data supply unit in units of packets.

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