JP2003283511A - Transmitter-receiver and transmitting-receiving method, and network - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmitter-receiver and a transmitting-receiving method, and a network in which processing for synchronous data transmitting on a transmission side is simplified and an apparatus on a reception side is simplified. <P>SOLUTION: By newly adding a time information extracting part 12, a synchronizing packet extracting part 14, and a tag adding part 13 to a transmitter 4, time information for time setting within the network or time information added to synchronizing data on the transmitting side of a first 1394 bus 3 can be transferred to transmission on a wireless network 5 as it is, necessity for a transmitting apparatus to the wireless network to perform again processing that is performed on the transmitting side of the first 1394 bus 3 is eliminated, and processing for synchronous data transmitting on the transmitting side is simplified. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission / reception device, a transmission / reception method, and a network, and more particularly to a relay method in two networks having different transmission systems.

[0002]

2. Description of the Related Art IEEE 1394 High Performance is a standard for transmitting synchronous data, such as video and audio, which requires some time-axis synchronization between the transmitting side and the receiving side.
There is a Signal Bus standard (hereinafter referred to as "1394 bus"), i. It is mounted on the device as a LINK, FireWire, or DV (Digital Video) terminal.

On the 1394 bus, for example, MPE
In order to transmit synchronous data in the G2 Transport Stream (TS), time information is transmitted to all devices (nodes) on the 1394 bus by a special packet called a cycle start packet, and each device on the 1394 bus is transmitted. The timer (cycle timer) is synchronized. The mechanism for transmitting synchronous data on the 1394 bus is
It is defined by the IEC 61883 standard. In this standard, the time when an MPEG2-TS packet is input to the 1394 interface from the application of the device is sampled based on the cycle timer,
An offset value is added to the time information sampled in each MPEG2-TS packet and added as a source packet header, and CIP (Common I
Sochronous Packet) header and isochronous packet header (Isochronous P)
packet header) is added and transmitted as an isochronous packet.

On the receiving side, the source packet header added with the MPEG2-TS packet is extracted from the isochronous packet, and the relative interval (time axis) between the MPEG2-TS packets is restored from the time indicated by the source packet header. To do. By doing so, the MPEG2 TS packets are sent to the application on the receiving side at the same intervals as the time interval of the MPEG2-TS packet on the application on the transmitting side.
It becomes possible to output a 2-TS packet. That is, the fixed delay line is equivalent on the 1394 bus.

There is IEEE1394.1 as a standard for relaying (bridge) between the 1394 buses. This standard is a standard for relaying 1394 buses to each other. Each 1394 bus is treated independently, and when relaying from one 1394 bus to another 1394 bus, the relay device uses the information of the other party, the information of the destination, and the 1394 bus. It is a standard that performs necessary processing such as correcting the bus time axis.

[0006] For example, as a technique for synchronizing the clock signals of a transmitting terminal and a receiving terminal, Japanese Patent Laid-Open No. 2000-33
The following technology is disclosed in Japanese Patent No. 2802. That is, the transmitting terminal that transmits the real-time data adds the counter value of the synchronization counter at the time of transmitting the packet to the packet formed by the packet generation unit as a time stamp and transmits the packet. The receiving terminal receiving the real-time data extracts the added time stamp from the received packet. Based on this time stamp and the count value of the synchronization counter at the time of packet reception at the receiving terminal, the deviation between the clock signal used at the transmitting terminal and the clock signal used by the receiving terminal is detected, and the deviation is detected according to this deviation. , The clock signal is synchronized by controlling the oscillation frequency of the VCO (voltage control type variable frequency oscillator) of the receiving terminal.

On the other hand, regarding transmission of synchronous data in a wireless network, Japanese wireless 1394 (ARIB
STD-T71) standard and European ETSI BRAN (E
European Telecommunication
s Standards Institute Broa
dband Radio Access Network
It is standardized in s), and both of the standards have a mechanism that can be processed as a 1394 bus by the application of the installed device.

A synchronous data transmission method in a wireless network capable of synchronous data is the same as that of the 1394 bus, but the isochronous cycle (I
Instead of sochronous Cycle (125μs), 4ms (Wireless 1394) or 2ms (ET
The time information is synchronized between the devices in a relatively long time period called “frame” such as SI BRAN). During this frame period, a plurality of packets are stored with the structure of the isochronous packet on the 1394 bus as it is and transmitted on the wireless network.

[0009]

However, in the above-mentioned prior art, when the synchronous data is relayed and transmitted from the 1394 bus to the wireless network capable of synchronous transmission, the synchronous transmission is performed on both the 1394 bus and the wireless network. Therefore, there is a problem that a timer having a relatively large number of bits and a circuit for adding time information to the synchronization data are doubly required.

Further, in the wireless network, the frame period is as large as 2 ms or 4 ms as compared with the 1394 bus, and therefore the transmission jitter is also large, and therefore a buffer having a large capacity is required on the receiving side to absorb the transmission jitter. There was a problem.

Therefore, an object of the present invention is to provide a transmission / reception device, a transmission / reception method, and a network which can simplify the process for transmitting synchronous data on the transmission side and simplify the device on the reception side.

[0012]

In order to achieve the above object, a transmitting apparatus of the invention according to claim 1 is a first network between two networks which perform synchronous transmission of data and have different transmission systems. In a transmitting device that transmits data received from a terminal connected via a network to a second network, synchronization transmitted on the first network for time synchronization between the terminals on the first network The synchronization time information extraction means for extracting the time information, the synchronization packet extraction means for extracting the synchronization packet transmitted on the first network, and the synchronization time information extracted by the time information extraction means are the synchronization time information. Identification information adding means for adding identification information for identifying that, the synchronization time information and the synchronization packet to which the identification information is added by the identification information adding means, respectively. Characterized in that a separate packet or a packet generating means for generating a single packet.

According to a second aspect of the present invention, there is provided a transmitting device according to the first aspect, wherein the first network is a wired network and the second network is a wireless network.

According to a third aspect of the present invention, there is provided a receiving device, which performs synchronous transmission of data, receives data to be transmitted on a second network between two networks having different transmission systems, and sets the first network to the first network. In the receiving device for transmitting to the terminal connected via the other network time information extracting means for extracting the synchronization time information transmitted via the second network, and the synchronization extracted by the other network time information extracting means. Timer means driven in synchronization with time information, other network time information extraction means for extracting time information added to the synchronization data from the synchronization packet transmitted via the second network, and the timer And the synchronization time information extracted from the other network time information extraction means, is transmitted via the second network. It is characterized by comprising a time-base recovery means for restoring the time axis of synchronous data in synchronization packet has.

[0015] According to a fourth aspect of the present invention, in the receiving apparatus according to the third aspect, the first network is a wired network and the second network is a wireless network.

According to a fifth aspect of the present invention, in a network for synchronously transmitting data, data transmitted from a terminal connected via a first network is transmitted between two networks having different transmission systems from each other. In a network including a transmitting device for transmitting to a network and a receiving device for receiving data transmitted on a second network and transmitting the data to a terminal connected via a third network, Synchronous time information extracting means for extracting synchronous time information transmitted on the first network to synchronize time between terminals on the network, and synchronous packets transmitted on the first network. Sync packet extraction means and identification information for identifying that the sync time information extracted by the time information extraction means is sync time information The receiving device further comprises: identification information adding means for adding the synchronization time information and the synchronization packet, to which the identification information is added by the identification information adding means, respectively, as separate packets or as one packet. Other network time information extraction means for extracting the synchronization time information transmitted through the second network, and timer means driven in synchronization with the synchronization time information extracted by the other network time information extraction means. , Other network time information extraction means for extracting time information added to the synchronization data from the synchronization packet transmitted through the second network, and the timer and the other network time information extraction means. The synchronization time information allows the same packet in the synchronization packet transmitted via the second network. Characterized in that a time-base recovery means for restoring the time axis of data.

According to a sixth aspect of the present invention, in the fifth aspect, the first network and the third network are wired networks, and the second network is a wireless network. .

According to a seventh aspect of the transmission method of the present invention, the data transmitted from the terminal connected via the first network is transmitted between the two networks which perform the synchronous transmission of data and have different transmission methods. In the transmission method of transmitting to the second network, the synchronization time information transmitted on the first network is extracted in order to synchronize the time between the terminals on the first network and transmitted on the first network. The synchronization packet is extracted, the identification information for identifying the synchronization time information is added to the extracted synchronization time information, and the synchronization time information and the synchronization packet to which the identification information is added are different packets, or It is characterized in that it is generated as one packet and is transmitted to the second network in synchronization with the synchronization cycle in the second network.

The transmission method of the invention according to claim 8 is the transmission method according to claim 7, characterized in that the first network is a wired network and the second network is a wireless network.

According to a ninth aspect of the present invention, there is provided a receiving method, in which data to be transmitted on a second network is received between two networks having different transmission systems by performing synchronous transmission of the data and transmitting the data to the first network. In the receiving method of transmitting to the terminal connected via the second network, the synchronization time information transmitted on the second network is extracted, the timer is synchronized with the extracted synchronization time information, and the transmission is performed via the second network. The time information added to the synchronization data is extracted from the received synchronization packet, and the time axis of the synchronization data in the synchronization packet transmitted via the second network is restored.

The receiving method of the invention according to claim 10 is the receiving method according to claim 9, wherein the first network is a wired network and the second network is a wireless network.

With such a configuration, the present invention can provide a transmission / reception device, a transmission / reception method, and a network that can simplify the process for transmitting synchronous data on the transmission side and simplify the device on the reception side. Become.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a network system using a transmission / reception apparatus according to an embodiment of the present invention. In this network system, the first network conforms to the IEEE 1394 standard, and the second network conforms to a wireless network having a mechanism for guaranteeing transmission of a synchronous packet for each frame period such as wireless 1394, and is adapted to both networks. The operation will be described when the IEC61883 standard is applied as the synchronous data transmission standard. Also, the synchronization data to be transmitted is
This will be described using MPEG2-TS packets. This network system is i. This is an example in which devices (for example, a digital television and a digital recorder) having 1394 bus terminals such as LINK terminals are connected by a wireless network instead of being connected by a wired 1394 bus.

In the network system shown in FIG. 1, the digital television (DTV) 1 is the transmission source, and the MPEG2-T
Digital recorder (D-VHS) that receives S packets
Send to 2. The DTV 1 is connected to the transmitting device 4 via the first 1394 bus 3. This transmitter 4 is the first
1394 bus interface for connecting to the 1394 bus 3 and a wireless network interface for connecting to the wireless network 5. Details of the transmitter 4 will be described later.

On the other hand, the receiving D-VHS2 is the second 13
It is connected to the receiving device 7 via the 94 bus 6. This receiving device 7 also has a 139 for connecting to the second 1394 bus 6.
A four-bus interface and a wireless network interface for connecting to the wireless network 5 are provided.
Details of the receiving device 7 will be described later.

The first 1394 bus 3 and the second 1394 bus 6 are the above-mentioned first network and are networks defined by the 1394 bus standard. Further, the wireless network is a transmission method different from that of the first network, is the above-mentioned second network, and is a wireless network having a mechanism of synchronous transmission.

The synchronization of transmission in this network is as follows. The time information in the cycle start packet transmitted by the DTV 1 to the first 1394 bus 3 and the time information in the source packet header added to the MPEG2-TS are "synchronization of the first 1394 bus 3" in FIG. The same value is used up to the internal processing of the receiving device 7 as shown in "System", while the same value is used on the second 1394 bus 6 as shown in "Synchronous system of second 1394 bus 6". The MPEG2-TS packet is transmitted by using time information and time information different from those of the 1394 bus 3 of No. 1. The details will be described later in the description of the transmission device 4 and the reception device 7.

Next, details of the transmitter 4 will be described with reference to FIG. The transmission device 4 includes a first 1394 bus interface unit (first 1394 bus I / F unit) 11 connected to the first 1394 bus 3. The first 1394 bus I / F unit 11 is a first 1394 bus I / F unit.
It is connected to a time information extraction unit 12 that extracts time information from a start packet that transmits time information on the 1394 bus received by the F unit 11. This time information extraction unit 12
It is connected to a tag adding unit 13 that adds a tag that identifies that the extracted time information is time information.

This transmitting device 4 is the first 1394 bus I.
The sync packet extraction unit 14 extracts the isochronous packet received by the / F unit 11. The synchronization packet extracted by the synchronization packet extraction unit 14 and the tag addition unit 1
A packet generation unit 15 for packetizing the time information tagged in 3 is provided. Furthermore, the packet generator 1
5 is connected to a first wireless network interface unit (first wireless network I / F unit) 16 for connecting to the wireless network 5. The first wireless network I / F unit 16 has a function of synchronous transmission.

The operation of the transmitter 4 will be described with reference to FIG. FIG. 3A schematically shows a signal transmitted on the first 1394 bus 3 which is an input of the transmission device 4. As shown in FIG. 3A, the cycle start packet 21 and the isochronous packet (synchronization packet) 22 transmitted on the 1394 bus 3 are transferred to the first 13
The signal is received by the 94 bus I / F unit 11.

This isochronous packet 22 is shown in FIG.
As shown in (c), an MPEG2-TS packet 25 including contents such as video information, a source packet header 26, a CIP (Common Isochronous).
Packet header 27, isochronous packet header (Isochronous Packet Head)
er) 28. Source packet header 26
Uses the cycle timer as a reference to sample the time when the MPEG2-TS packet is input from the application of DTV1 to the 1394 interface provided in the signal output unit of DTV1, and each MPE is sampled.
The offset value is added to the time information sampled in the G2-TS packet.

The format of the CIP header 27 is defined by the IEC61883 standard.
According to the standard, the header is always used when transmitting an MPEG2-TS packet in a BS digital tuner or DV format data of a DV camera, and its structure is partially changed depending on the type of data to be transmitted. The CIP header 27 is located at the head of the data area of the isochronous packet in IEEE 1394, and its size is 2 quadlet.
(64 bits).

The isochronous packet header 28 contains the I
It is a header whose format is defined by the EEE1394 standard, is always located at the beginning of an isochronous packet, and its size is 1 quadlet (32 bits).

The time information extraction unit 12 extracts the cycle start packet 21 as it is or extracts only the time information in the cycle start packet 21. The tag adding unit 13 adds a tag to the extracted time information so that the receiving device 7 can identify the time information. Here, it is possible to add a value indicating a period (125 μs in the IEEE 1394 standard) in which the cycle start packet 21 is transmitted together with the tag.

On the other hand, the isochronous packet 22 is extracted by the sync packet extraction unit 14. Here, it may be possible to extract only the isochronous packet 22 that needs to be transmitted to the wireless network 5. In the packet generation unit 15, the extracted cycle start packet 21
And the isochronous packet 22 are packetized so that the order is not exchanged. Here, if there is no isochronous packet 22 between the cycle start packet 21 and the next cycle start packet 21, the packet is composed of only the cycle start packet 21.
In addition, the isochronous packet 22 is MPEG2-TS.
Even in the case of not including a packet (empty packet in the IEEE 1394 standard), packetization is similarly performed.

In the first wireless network I / F unit 16, the output of the packet generation unit 15 is packetized in a format conforming to the protocol of the wireless network 5, and as shown in FIG. Frame period 2
It is added to the head of 4 and transmitted to the wireless network 5.
Further, using the frame sync 23, the wireless network 5
Processing is also performed so that the above can be synchronized. The cycle of the frame sync 23 and the cycle start packet 21 need not be synchronized.

As described above, by adding the time information extraction unit 12, the synchronization packet extraction unit 14, and the tag addition unit 13 to the transmission device 4, the transmission is performed on the transmission side of the first 1394 bus 3. The time information in the network for time adjustment and the time information added to the synchronization data are stored in the wireless network 5
It becomes possible to directly shift to the above transmission, and the first 1394
The processing performed on the transmission side of the bus 3 can be eliminated again by the transmission device to the wireless network, and the processing for synchronous data transmission on the transmission side can be simplified.

Next, the configuration of the receiving device 7 will be described with reference to FIG. The receiving device 7 includes a second wireless network interface unit (second wireless network I / F unit) 31 for connecting to the wireless network 5. Further, the receiving device 7 extracts the time information transmitted from the transmitting device 4, the other network time information extracting unit 32, and the timer unit 33 synchronized with the time on the first 1394 bus 3 using the extracted time information. (The timer 33 indicates the reference time in the time axis restoration unit 36 in the receiving device 7), the transmitting device 4
Another network time information extraction unit 34 for extracting the cycle start packet 21 added to the MPEG2-TS from the isochronous packet 22 re-packetized and transmitted by the isochronous packet re-packetized and transmitted by the transmitter 4. 22 to MPEG2-TS
A synchronous data extraction unit 35 that extracts packets, and a time axis restoration unit 36 that restores a relative time interval between MPEG2-TS packets inside the DTV 1, that is, a time axis restoration unit 36 are provided.

Further, the receiving device 7 is provided with a second 1394
A second 1394 bus interface unit (second 1394 bus I / F unit) 37 for connecting to the bus 6 is also provided.

Next, the operation of the receiving device 7 will be described. The second wireless network I / F unit 31 receives the packet transmitted on the wireless network 5. The other network time information extraction unit 32 extracts time information from the tag added by the tag addition unit 13. At this time, if the information about the cycle is added at the same time, the timer unit 33
Output to. The timer unit 33 loads time information every 125 μs to synchronize with the time of the cycle timer on the first 1394 bus 3.

On the other hand, the other network time information extraction unit 34
Then, from the isochronous packet 22 stored in the frame period 24 (FIG. 3B) to the MPEG2-T.
The source packet header added to each S packet is extracted. In the synchronous data extraction unit 35, the frame period 2
4 only the MPEG2-TS packet is extracted from the isochronous packet 22 stored in 4.

Further, in the time axis restoration unit 36, each MPEG2-TS packet to which time information has been added is divided at the timing indicated by the other network time information extraction unit 34 with reference to the time indicated by the timer unit 33. Two
Is output to the 1394 bus I / F unit 37. Second one
In the 394 bus I / F unit 37, the input MPEG
2-TS packet based on IEC61883 standard and IEEE1
Performs processing in accordance with the 394 standard, and the second 1394 bus 6
Output to.

As described above, the receiving apparatus 7 is newly provided with the other network time information extracting unit 32, the timer unit 33, the other network time information extracting unit 34, and the time axis restoring unit 36, and thus the first device is provided. For the synchronous data relayed from the 1394 bus 3 and transmitted on the wireless network 5, the capacity of the buffer for absorbing the jitter can be reduced, and the receiving device 7 can be simplified.

The present invention is not limited to the above embodiments as long as it does not depart from the spirit of the invention.

[0045]

According to the invention described in detail above, it is possible to provide a transmission / reception device, a transmission / reception method, and a network in which the processing for transmitting synchronous data on the transmission side can be simplified and the device on the reception side can be simplified. Becomes

[Brief description of drawings]

FIG. 1 is a block diagram showing a network according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of the transmission device of FIG.

FIG. 3 is a schematic diagram showing an operation of the transmission device of FIG.

FIG. 4 is a block diagram showing the configuration of the receiving apparatus shown in FIG.

[Explanation of symbols]

1 ... Digital TV (DTV), 2 ... Digital recorder (D-VHS), 3 ... the first 1394 bus, 4 ... transmitter, 5 ... wireless network, 6 ... the second 1394 bus, 7 ... Receiving device, 11 ... First 1394 bus interface section, 12 ... Time information extraction unit, 13 ... tag addition section, 14 ... Sync packet extraction unit, 15 ... Packet generator 16 ... A first wireless network interface unit, 21 ... Cycle start packet, 22 ... Isochronous packet, 23 ... Frame sync, 24 ... frame period, 25 ... MPEG2-TS packet, 26 ... Source packet header, 27 ... CIP header, 28 ... Isochronous packet header, 31 ... A second wireless network interface unit, 32 ... Other network time information extraction unit, 33 ... Timer part, 34 ... Other network time information extraction unit, 35 ... Synchronous data extraction unit, 36 ... Time axis restoration unit, 37 ... Second 1394 bus interface section.

Claims (10)

[Claims] 1. A transmitting device for transmitting data received from a terminal connected via a first network between two networks different in transmission method from each other by performing synchronous transmission of data, to a second network. Synchronous time information extracting means for extracting synchronous time information transmitted on the first network to synchronize time between terminals on the first network, and a synchronous packet transmitted on the first network. Synchronization packet extraction means for extracting the identification information, identification information addition means for adding identification information for identifying the synchronization time information to the synchronization time information extracted by the time information extraction means, and identification information for the identification information addition means. And a packet generation means for generating the synchronization time information added with and the synchronization packet as separate packets or one packet. Transmission and wherein the a. 2. The transmission device according to claim 1, wherein the first network is a wired network and the second network is a wireless network. 3. Synchronous transmission of data, reception of data transmitted on a second network between two networks having different transmission methods, and transmission to a terminal connected via the first network. In the receiving device, the second
Second network time information extraction means for extracting the synchronization time information transmitted through the network of the second network, timer means driven in synchronization with the synchronization time information extracted by the other network time information extraction means, and Other network time information extracting means for extracting the time information added to the synchronization data from the synchronization packet transmitted via the network of the above, and the synchronization time information extracted from the timer and the other network time information extracting means. According to the above, the receiving device is provided with a time axis restoring means for restoring the time axis of the synchronization data in the synchronization packet transmitted via the second network. 4. The receiving apparatus according to claim 3, wherein the first network is a wired network and the second network is a wireless network. 5. A transmission device for transmitting data transmitted from a terminal connected via a first network between two networks having different transmission systems, which performs synchronous transmission of data, to a second network. In a network including a receiving device that receives data transmitted on a second network and transmits the data to a terminal connected via a third network, the transmitting device transmits time between each terminal on the first network. Synchronization time information extracting means for extracting synchronization time information transmitted on the first network to perform synchronization of the packets, synchronization packet extracting means for extracting synchronization packets transmitted on the first network, and the time. Identification information adding means for adding identification information for identifying the synchronization time information to the synchronization time information extracted by the information extracting means; The receiving device is transmitted via the second network, comprising: the synchronization time information to which the identification information is added by the information adding means and the packet generating means for generating the synchronization packet as separate packets or one packet. Other network time information extracting means for extracting the synchronized time information, the timer means driven in synchronization with the synchronized time information extracted by the other network time information extracting means, and transmitted via the second network. The other network time information extraction means for extracting the time information added to the synchronization data from the received synchronization packet, and the synchronization time information extracted from the timer and the other network time information extraction means, to establish the second network. Axis restoration to restore the time axis of the synchronization data in the synchronization packet transmitted via Network, characterized in that a stage. 6. The network according to claim 5, wherein the first network and the third network are wired networks, and the second network is a wireless network. 7. A transmission method for transmitting data transmitted from a terminal connected via a first network between two networks having different transmission methods by performing synchronous transmission of data to a second network. , Extracting synchronization time information transmitted on the first network for time synchronization between the terminals on the first network, extracting a synchronization packet transmitted on the first network, and extracting The identification information for identifying the synchronization time information is added to the synchronization time information, and the synchronization time information and the synchronization packet to which the identification information is added are different packets,
Alternatively, it is generated as one packet, and is transmitted to the second network in synchronization with the synchronization cycle of the second network. 8. The transmission method according to claim 7, wherein the first network is a wired network, and the second network is a wireless network. 9. Synchronous transmission of data is performed, and between two networks having different transmission systems, data transmitted on the second network is received and transmitted to a terminal connected via the first network. In the receiving method, the second
The synchronization time information transmitted over the second network is extracted, the timer is synchronized with the extracted synchronization time information, and the time added to the synchronization data from the synchronization packet transmitted over the second network. Extract the information,
A receiving method characterized by restoring the time axis of the synchronization data in the synchronization packet transmitted via the second network. 10. The receiving method according to claim 9, wherein the first network is a wired network and the second network is a wireless network.