JP2009071705A - Transmission frame format and method of transmitting the same, multiplexer and separator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that in distributing broadcast signals by a conventional optical fiber, there is not yet provided a means for distributing the broadcast signals whose required band is guaranteed for channels assigned to each broadcast station, thereby assuring the required band for each channel as well as eliminating the need of a request for receiving signals from a receiving side. <P>SOLUTION: In distributing broadcast signals, predetermined numbers of subframes 1-1, 1-2, ... k-N are assigned to each broadcast station and there is provided such a frame configuration that is time multiplexed in a frame corresponding to one line for all broadcast stations. The required band is assured for each channel by changing the number of subframes assigned to each channel. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an FTTH broadcast distribution method for efficiently distributing broadcast signals at low cost by FTTH (Fiber-To-The-Home). In particular, broadcast signals from each broadcast station are multiplexed in the time domain, and the multiplexed broadcast signals are transmitted in one direction and one-to-one between the head-end station-side transmission device and the subscriber-side subscriber-side transmission device. Or it is related to the FTTH broadcast distribution system for performing one-to-many distribution.

  Conventionally, broadcast signal distribution methods using FTTH are roughly classified into a method of distributing in an optical fiber in an RF (Radio Frequency) format and a method of distributing in an IP (Internet Protocol) packet. As a method of distributing in RF format, a method of performing FM (Frequency Modulation) collective conversion of broadcast signals multiplexed by FDM (Frequency Division Multiplexing) in an electric stage and distributing them to an optical fiber (for example, see Non-Patent Document 1). There is a method of distributing broadcast signals that are FDM multiplexed at the electrical stage by IM (Intensity Modulation) modulation (see, for example, Non-Patent Document 2).

  FIG. 7 is a schematic diagram showing an example of a conventional broadcast signal, where (a) shows a frequency arrangement in terrestrial digital broadcasting, and (b) shows a band in one carrier wave. The signal band of radio broadcasting is affected by the band limitation. For example, in the case of terrestrial digital broadcasting, radio waves in the UHF (Ultra High Frequency) band are limited to 5.58 MHz per carrier. This is due to the rarity of radio waves. Further, one broadcasting station A, B, C is allowed to use only one carrier except for a special broadcasting organization such as the Japan Broadcasting Corporation.

  In the terrestrial digital broadcast distribution by radio waves, it is necessary to distribute with the bandwidth of 5.58 MHz. Therefore, the maximum information rate is 64QAM (Quadrature Amplitude Modulation) modulation and OFDM (Orthogonal Frequency Division Multiplexing) multiplexing result. 23.234 Mbps. Therefore, in a video signal having a large amount of information, it is essential to compress the information by a video encoding method such as MPEG (Motion Picture Experts Group) -2.

  For example, in order to send one channel (ch) of an HD (High Definition) TV, an uncompressed HD signal of about 1.5 Gbps must be MPEG2 compressed to about 20 Mbps. In BS (Broadcasting Satellite) digital broadcasting and CS (Communications Satellite) digital broadcasting, the allocated bandwidth is larger than terrestrial digital broadcasting. For example, in BS digital broadcasting, it is 34.5 MHz, and the maximum information rate is about 52.17 Mbps by QPSK (Quadrature Phase Shift Keying) modulation. However, the HD signal must be reduced to an information rate lower than 52.17 Mbps by MPEG-2 compression.

  In order to transmit a broadband broadcast signal exceeding these information rates, it is necessary to increase the modulation speed or perform multi-level modulation. However, an increase in modulation speed increases the bandwidth, which is difficult due to the rarity of radio waves. Further, multi-level modulation increases the complexity of the receiving circuit, and the allowable CNR (Carrier-to-Noise Ratio). ), Which is difficult. Accordingly, it has not been possible to distribute broadband broadcast signals such as higher-definition video and high-quality audio signals by radio waves.

  In addition, the broadcast distribution method using optical fiber based on the RF method is premised on the redistribution of radio broadcasts, so it can distribute broadband broadcast signals such as higher-definition video and high-quality audio signals. In this case, since it is subject to the same restrictions as broadcasting by radio waves, this has not been realized.

  On the other hand, as a method of distributing IP packets, a completely standardized distribution method has not been determined, and service providers often use an original method. The common point is that a mechanism for selecting a program by a multicast router in the network is used.

  With regard to delivery using the IP packet method, problems such as radio wave band limitation do not occur because it is not the RF method. However, fluctuations and delays occur in the packet arrival time due to switching and routing in switches and routers in the network. Or

  FIG. 8 is a schematic configuration diagram showing a distribution form by conventional IP broadcasting. In broadcast distribution using the IP multicast technology, broadcast contents are transferred from the distribution servers 11a, 11b, and 11c of each broadcast station to the network 10 for multicast distribution. For example, the broadcast server A distribution server 11a receives the packets 101-1, 101-2, and 101-4, the broadcast station B distribution server 11b receives the packets 101-3 and 101-6, and the broadcast station C distribution server 11c. Packets 101-5 and 101-7 are transferred to the network 10.

  In the network 10 shown in FIG. 8, a plurality of multicast routers 21a and 21b corresponding to multicast are provided. The multicast router 21a and the multicast router 21b search each other for multicast rendezvous points (routers that play a central role) such as PIM-SM (Protocol Independent Multicast-Spare Mode) and PIM-DM (Protocol Independent Multicast-Dense Mode). Exchange packets related to other protocols and find the best multicast point. The broadcast viewer transmits a viewing request from the terminal device 12 to the multicast router 21b, selects a program to be viewed on the multicast router 21b, and the selected broadcast signal is sent to the viewer's terminal.

  Further, IP packets from the broadcast stations A, B, and C that are packet-multiplexed are transmitted on the network 10 in a random positional relationship. This is a random positional relationship unless an algorithm is applied to guarantee that the IP packets input to all switches and routers that store and forward IP packets in the network 10 are output in a regular order and interval. It is because it ends up. Because of this situation, a buffer having a large capacity is provided in the terminal device 12, and after rearranging the packet on the terminal device 12 side, the packet is transferred to the MPEG-2 decoding system, so that the real-time property is impaired. There are many.

  Further, in the distribution by the IP packet system, the original broadcast signal may be an uncompressed broadcast signal or a compressed broadcast signal in order to convert the broadcast signal into an IP packet. The number of IP packets increases when the compression rate is high and the encoding rate is high compared to the case where the original broadcast signal is highly compressed and the encoding rate is reduced. For this reason, many resources in the network are used for the transfer. Therefore, in the case of an encoding rate that does not compress the original broadcast signal so much, exceeding a certain threshold may cause network congestion. Also, as the number of viewers increases or the number of viewing requests increases, the processing for viewing increases each time, and this processing packet may cause network congestion as described above.

  In addition, the current broadcast distribution using IP multicast mostly distributes at a low bit rate, and absorbs fluctuations in packets due to network congestion, so that playback of video and audio on a playback device is smooth. In many cases, a large number of reception buffers are installed in the player. In this case, since a large amount of data is accumulated in the reception buffer, the real-time property is impaired. Therefore, in such a reception environment, it is not suitable for distribution of a signal with real-time characteristics such as a broadcast signal by a current radio wave.

  FIG. 9 is an example of a flow when receiving broadcast distribution using IP. The flow of signals exchanged between the multicast router 21 and the terminal device 12 is shown. In this example, multicast is used as a channel selection mechanism. The terminal device 12 transmits a participation request signal Join (ch1) for viewing the ch1 program to the multicast router 21. After receiving the participation request Join (ch1), the multicast router 21 transmits the requested broadcast signal to the terminal device 12. As a result, the terminal device 12 can view the ch1 program.

  Further, the case where the terminal device 12 switches from the ch1 broadcast signal to the ch2 broadcast signal will be described. In this case, the terminal device 12 transmits a ch1 leave request signal Leave (ch1) and a ch2 join request signal Join (ch2) to the multicast router 21. When the multicast router 21 receives the ch1 leave request signal Leave (ch1) from the terminal device 12, the multicast router 21 stops the distribution of the ch1 broadcast signal to the terminal device 12. Further, when receiving the ch2 participation request signal Join (ch2) from the terminal device 12, the multicast router 21 starts distributing the ch2 broadcast signal. Then, the selected ch2 can be viewed on the terminal device 12.

  Similarly, a case where switching is performed from the ch2 broadcast signal to the ch1 broadcast signal will be described. In this case, the terminal device 12 transmits a ch2 leave request signal Leave (ch2) and a ch1 join request signal Join (ch1) to the multicast router 21. Receiving the withdrawal request and the participation request, the multicast router 21 stops the broadcast signal of ch2 and transmits the selected broadcast signal of ch1 to the terminal device 12. Then, the selected ch1 can be viewed on the terminal device 12.

As described above, in the method of using the IP multicast technology for switching the broadcast channel, many control signals are exchanged between the multicast router 21 and the terminal device 12. Furthermore, since the multicast router 21 is usually connected to a plurality of terminal devices 12, it is considered that the load becomes very large. Therefore, there is a concern that scalability does not increase when broadcasting signals of the above-described high-encoding rate such as HDTV in a form using IP packets.
K. Kikushima, H .; Yoshinaga, H .; Nakamoto, C.I. Kishimoto, M .; Kawabe, K .; Suto, K .; Kumozaki and N.K. Shibata, “A Super Wideband Optical FM Modulation Scheme for Video Transmission Systems”, IEEE J. Selected Areas in Communication, Vol. 14, no. 6, pp. 1066-1075, 1996. C. Lin, S .; 0vadia and T.W. Anderson, “Multichannel AM / QAM video lightwave systems for hybrid-fiber-coax distribution networks, in Proc. IOOC, Hong Kong, 1995.

  As described above, in the conventional broadcast distribution using optical fibers, there is no means for distributing a broadcast signal in which a desired band is guaranteed for a channel assigned to each broadcast station. Therefore, the present invention has an object of delivering a broadcast signal that guarantees a desired band for each channel and that does not require a reception request from the receiving side.

  In order to solve the above-mentioned problems, the present invention is characterized in that in broadcasting signal distribution using an optical fiber, a predetermined number of subframes are allocated to each broadcasting station, and the subframes are multiplexed for all broadcasting stations. And By changing the number of subframes assigned to each channel used by each broadcasting station, a desired band can be guaranteed for each channel. Therefore, it is possible to distribute a broadcast signal that guarantees a desired band for each channel and that does not require a reception request from the receiving side.

The transmission frame format according to the present invention is:
A transmission frame format for distributing broadcast signals of a plurality of channels over an asynchronous packet network,
A transmission frame of a predetermined capacity is periodically repeated,
The transmission frame comprises more subframes than the number of channels;
The number of subframes assigned to a channel is variable.
By assigning a desired number of broadcast signals of each channel to one transmission frame, a desired band can be guaranteed for each channel of each broadcast station. Furthermore, since a broadcast signal for each channel is stored in one transmission frame, a reception request from the reception side is not necessary. Further, since the transmission frame storing the broadcast signal of each channel is periodically repeated, the buffer on the terminal device side that receives the broadcast signal can be reduced.

  In the transmission frame format according to the present invention, it is preferable that the transmission frame is composed of a plurality of fixed-length subframes. Since the subframe has a fixed length, the position of the subframe can be changed without changing the guaranteed bandwidth. This makes it possible to easily increase or decrease the bandwidth guaranteed for each channel.

In the transmission frame format according to the present invention,
The broadcast signal is preferably stored in a predetermined subframe in the transmission frame. Since the transmission frame is periodically repeated, the broadcast signal is stored in a predetermined subframe, thereby facilitating reconstruction of the broadcast signal in real time.

The transmission method according to the present invention includes:
A transmission method for distributing broadcast signals of a plurality of channels over an asynchronous packet network,
Periodically repeat a transmission frame of a predetermined capacity,
The transmission frame comprises more subframes than the number of channels;
The number of subframes allocated to a channel is variable.
By assigning a desired number of broadcast signals of each channel to one transmission frame, a desired band can be guaranteed for each channel of each broadcast station. Furthermore, since a broadcast signal for each channel is stored in one transmission frame, a reception request from the reception side is not necessary. Further, since the transmission frame storing the broadcast signal of each channel is periodically repeated, the buffer on the terminal device side that receives the broadcast signal can be reduced.

  In the transmission method according to the present invention, it is preferable that the transmission frame is composed of a plurality of fixed-length subframes. Since the subframe has a fixed length, the position of the subframe can be changed without changing the guaranteed bandwidth. This makes it possible to easily increase or decrease the bandwidth guaranteed for each channel.

  In the transmission method according to the present invention, the broadcast signal is preferably stored in a predetermined subframe in the transmission frame. Since the transmission frame is periodically repeated, the broadcast signal is stored in a predetermined subframe, thereby facilitating reconstruction of the broadcast signal in real time.

The multiplexing device according to the present invention is
A subframe generating unit for generating a subframe of a predetermined capacity;
A broadcast signal input section for inputting broadcast signals of a plurality of channels;
A table storage unit for storing a channel information table for assigning a predetermined number of subframes for each channel in a predetermined order;
And a subframe multiplexing unit that stores the broadcast signal input to the broadcast signal input unit in the subframe generated by the subframe generation unit according to the channel information table.
By assigning a desired number of broadcast signals of each channel to one transmission frame, a desired band can be guaranteed for each channel of each broadcast station. Furthermore, since a broadcast signal for each channel is stored in one transmission frame, a reception request from the reception side is not necessary. Further, since the transmission frame storing the broadcast signal of each channel is periodically repeated, the buffer on the terminal device side that receives the broadcast signal can be reduced.

The separation device according to the present invention is:
A separation device for separating a transmission frame in which broadcast signals of a plurality of channels are time-multiplexed,
The transmission frame is
A plurality of subframes having a predetermined capacity are time-multiplexed,
A predetermined number of the subframes for each channel are allocated in a predetermined order;
A table storage unit that stores a channel information table that allocates a predetermined number of subframes for each channel in a predetermined order;
A control signal input unit to which a control signal designating a specific channel is input;
A transmission frame input unit to which the transmission frame is input;
A frame analysis unit for analyzing a frame format of the transmission frame input to the transmission frame input unit;
A subframe read control unit that reads out a broadcast signal stored in a subframe of a channel specified by the control signal input to the control signal input unit according to an analysis result of the frame analysis unit; To do.
By assigning a desired number of broadcast signals of each channel to one transmission frame, a desired band can be guaranteed for each channel of each broadcast station. Further, since the broadcast signal of each channel is stored in one transmission frame, a reception request from the reception side is not necessary. Furthermore, since the transmission frame storing the broadcast signal of each channel is periodically repeated, the number of buffers on the terminal device side that receives the broadcast signal can be reduced.

In the separation device according to the present invention,
The broadcast signal includes time slot information indicating a time slot interval,
It is preferable to further include a time slot reconfiguration unit that reconfigures the broadcast signal read by the subframe read control unit according to the time slot information. Since the time slot reconstruction unit reconstructs the broadcast signal at the correct timing, a time lag when generating the broadcast signal can be prevented.

  According to the present invention, a desired band can be guaranteed for each channel of each broadcasting station. Furthermore, a reception request from the receiving side is not necessary. Furthermore, the buffer on the terminal device side that receives the broadcast signal can be reduced. According to the present invention, it is possible to realize data broadcasting having higher definition video, higher sound quality sound, and more information in real time.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiment described below is an example of the configuration of the present invention, and the present invention is not limited to the following embodiment.

Example 1
FIG. 1 is a schematic configuration of a system for distributing a transmission format according to the present embodiment. This shows a case where a broadcast signal of high-definition video is distributed from the multiplexing device 13 using FTTH broadcasting, and the separating device 14 at the viewer's house receives the broadcast signal. The multiplexing device 13 includes a broadcast signal 100-1 of the first broadcast station ch1, a broadcast signal 100-2 of the second broadcast station ch2, and a broadcast station chM of the Mth (M is a positive integer). Broadcast signal 100-M is input. Here, the broadcast signal from each broadcast station is, for example, a normally used TS (Transport Stream) packet. Then, the multiplexing apparatus 13 multiplexes all broadcast signals 100-1, 100-2,... 100-M transmitted from the respective broadcasting stations ch1, ch2,. The transmission frames 110-1, 110-2,... 110-k having a predetermined transmission frame format are distributed on the asynchronous packet network. Here, k is the number of transmission frames distributed by the multiplexing device per second, and is a positive integer. The separation device 14 separates the subframe assigned to ch2 designated by the viewer from the transmission frame distributed by the multiplexing device. Hereinafter, although an example in which each broadcast station distributes one channel will be described in the present embodiment, one broadcast station may distribute broadcast signals of a plurality of channels.

  In the transmission method according to the present embodiment, transmission frames 110-1, 110-2,... 110-k having a predetermined capacity are periodically repeated. For example, overhead, ch1, ch2, ch3,... ChM are multiplexed in the transmission frame 110-2. Further, broadcast signals from all broadcast stations are multiplexed in time in the transmission frames 110-1, 110-2,... 110-k. The transmission frames 110-1, 110-2,... 110-k each have a number of subframes larger than the number M of channels, and the number of subframes assigned to each of ch2,. Is variable for each channel. For example, one subframe is allocated to ch1, four subframes are allocated to ch2, one subframe is allocated to ch3, and two subframes are allocated to chM. The number of subframes assigned to each channel can be variable depending on the transmission frame. Even if the necessary bandwidth changes for each broadcasting station, the necessary bandwidth can be guaranteed by increasing or decreasing the number of subframes allocated to the channel of the broadcasting station.

  In FIG. 1, the viewer has selected the broadcast signal of ch2. For ch2, four subframes are allocated on the time axis in the transmission frame. This represents, for example, that the band is four times that of the broadcasting station 1. Now, assume that the number of transmission frames delivered per second is 2500 rows, and the number of subframes per transmission frame is 328 columns. Assume that the subframe is a MAC frame having a fixed length of 1522 bytes. In this case, the number of transmission frames k per second is 2500, and if it is repeated for 400 μsec, a bandwidth of about 30 Mbps is allocated to one subframe. Therefore, since the broadcasting station 2 occupies four subframes, a bandwidth of about 120 Mbps is periodically allocated. It is assumed that such bandwidth allocation is determined at the time of line contract. Although 120 Mbps is larger than the transmission band of terrestrial digital broadcasting and BS / CS digital broadcasting described so far, when 328 columns of subframes are repeated at 400 μsec intervals assumed here, the transmission capacity per second is 10 Gbits. is there. This transmission capacity is a realizable transmission capacity, and 10 Gbps is taken into account in this embodiment.

  In this way, by assigning subframes determined for each channel on the time axis, it is possible to distribute a broadcast signal with a guaranteed bandwidth to the separation device 14. Also, by assigning multiple subframes to one channel, broadcast signals with wider bandwidth than conventional ones can be distributed, such as radio broadcasts, and when the total transmission capacity is 10 Gbps, the minimum guarantee per broadcasting station If the transmission band is 30 Mbps, channels for 328 broadcast stations can be realized. This means that the bandwidth and the number of channels more than three times can be obtained as compared with the total information rate of the existing RF broadcast redistribution by the FM batch conversion method of about 3 Gbps.

  In the transmission frame transmission method according to the present embodiment, it is preferable that each of the transmission frames 110-1, 110-2,... 110-k is composed of a plurality of fixed-length subframes. For example, it is preferable that the capacity of one subframe to which ch1,... ChM is assigned is constant. If each subframe has a fixed length, the time slot of the subframe can be moved without changing the guaranteed bandwidth. For this reason, the increase / decrease of the sub-frame allocated to a channel becomes easy. By making the subframes of one channel continuous, the number of processing steps for reconstructing the broadcast signal performed at the distribution destination viewer's home can be reduced.

  In the transmission frame transmission method according to this embodiment, it is preferable that the broadcast signal of each channel is stored in a predetermined subframe in the transmission frame. For example, it is preferable that the time slot of each subframe of ch1, ch2, ch3,... ChM is predetermined. For example, in any of the transmission frames 110-1, 110-2,... 110-k, the ch1 broadcast signal is the first subframe, the ch2 broadcast signal is the second to fifth subframes, and chM. The broadcast signal is stored in the (N−1) th to Nth subframes. Since the transmission frames 110-1, 110-2,... 110-k are periodically repeated, the broadcast signal is stored in a predetermined subframe, so that it is easy to reconstruct the broadcast signal in real time. become.

(Embodiment 2)
FIG. 2 is a schematic configuration of a system for distributing a transmission format according to the present embodiment. A schematic diagram when a broadcast signal is distributed by a transmission frame of the present embodiment in a PON (Passive Optical Network) that is normally applied as an access network is shown. Broadcast signals from the respective broadcasting stations ch1, ch2,... ChM are multiplexed in the multiplexing device 13 of the head end 23. The multiplexing device 13 distributes the transmission frames 110-1, 110-2,... 110-k of the present embodiment in which the broadcast signals of the broadcasting stations ch1, ch2,. The multiplexed broadcast signal is distributed to the accommodation station 24a and the accommodation station 24b via the relay network. At this time, the transmission frames 110-1, 110-2,... 110-k are transmitted to all the accommodating stations 24a, 24b as in the normal broadcast distribution form without the information being replaced in the network. The In the access section from the accommodating stations 24a and 24b to the terminal device 26 at the subscriber's house, all broadcast signals are equivalently distributed to each terminal device 26 because it is a passive branch by an optical splitter. For example, each terminating device 26 receives a transmission frame 110-2 in which broadcast signals from ch1 to chM of each broadcasting station are multiplexed. The separation device 14 is installed at the subsequent stage of the termination device 26. When a control signal for channel selection is input to the separation device 14, the separation device 14 separates the input channel. Unlike the above-described distribution by the IP packet method, the present embodiment also has a feature of scalability because it is not channel selection by a multicast router.

  FIG. 3 schematically shows a transmission frame format according to the present embodiment. In the transmission frame format according to the present embodiment, a transmission frame having a predetermined capacity is periodically repeated. For example, k transmission frames 110-1 to 110-k from 1 to k (k is a positive integer) shown in FIG. 1 are repeated within a certain time. In FIG. 3, for convenience of explanation, it is shown as k rows. The transmission frame in each row has a predetermined capacity. For example, when the broadcast signal is a TS packet, the broadcast signal is transmitted as a DVB-ASI (Digital Video Broadcasting-Asynchronous Serial Interface) signal having a physical speed of 270 Mbps. In this case, a transmission frame having a capacity obtained by equally dividing the physical speed 270 Mbps into k is periodically repeated. For example, a transmission frame in the first row, a transmission frame in the second row, a transmission frame in the third row,.

  Each transmission frame from 1 to k rows is composed of smaller subframes. These subframes are multiplexed in time, and N subframes gather to form one transmission frame. For example, N subframes 1-1, 1-2, 1-3... 1-N in the first row are time-multiplexed to form a transmission frame in the first row. Similarly, N subframes k-1, k-2, k-3,..., KN in the kth row are time-multiplexed to form a transmission frame in the kth row.

  In the example of the present embodiment, a fixed-length MAC (Media Access Control) frame used in Ethernet (registered trademark) is assumed as a subframe. However, the subframe is not necessarily limited to a MAC frame. It can be realized if there is. Furthermore, the transmission frame of this embodiment can be constructed on a normal layer 2 (L2) packet network. In particular, in the case of constructing a subframe with a MAC frame, it is possible to transmit transparently through a network configured by ordinary Ethernet (registered trademark).

  In the transmission frame format according to the present embodiment, the transmission frame per row includes more subframes than the number of channels. For example, different subframes are assigned to the subframes 1-1 to kN for each broadcasting station. Therefore, the broadcast signal from the broadcast station is assigned to the determined time slot. Thereby, the band guarantee of the broadcast signal of the broadcasting station is realized on the time axis.

  In the transmission frame format according to the present embodiment, the number of subframes assigned to a channel is variable. For example, the number of assigned ch1 subframes in the first transmission frame may be one, and the number of ch1 subframes assigned in the first transmission frame may be two. By changing the number of assigned subframes for each channel, a desired band corresponding to the number of subframes can be guaranteed.

  In the transmission frame format according to the present embodiment, it is preferable that the transmission frame per row is composed of a plurality of fixed-length subframes. For example, it is preferable that the capacities of N subframes from 1-1 to 1-N are equal. Further, it is preferable that each subframe has a fixed length between transmission frames. Since the subframe has a fixed length, the time slot can be easily moved and the guaranteed bandwidth of each channel can be easily increased or decreased.

  In the transmission frame format according to the present embodiment, it is preferable that the broadcast signal of each channel is stored in a determined subframe in the transmission frame per line. For example, in each transmission frame from the first row to the k-th row, the ch1 broadcast signal is stored in the second column subframe, and the ch2 broadcast signal is stored in the third and fourth column subframes. It is preferable. Since it is stored in the time slot determined for each channel, the broadcast signal separation processing for each channel is simplified.

  In the transmission frame format according to the present embodiment, it is preferable that there is a frame synchronization signal in each transmission frame from 1 to k rows. For example, the frame synchronization signal is preferably stored in subframes 1-1, 2-1,... K-1 in the first column of the transmission frame. In this case, for example, the subframe 1-1 has an overhead (OH) storing a table indicating which channel's signal is stored in which subframe of the subframes 1-2 to 1-N in the first row and monitoring information. ) Is preferable.

  FIG. 4 is an example of subframes multiplexed in a transmission frame. 1 shows a method in which broadcast signals from the respective broadcasting stations ch1, ch2, ch3,... ChM described in FIG. 1 are multiplexed into a transmission frame according to the present embodiment. Overhead is stored in the first subframe of each transmission frame. That is, overhead is assigned to the first time slot 102 of each transmission frame. The broadcast signal of each channel is stored for each channel in a time slot which is a predetermined location of the transmission frame. For example, the ch1 broadcast signal is stored in the time slot 103-1 to which the second subframe of each transmission frame is assigned. The channel 2 broadcast signal is stored in the time slot 103-2 to which the third and fourth subframes of each transmission frame are assigned. A ch3 broadcast signal is stored in the time slot 103-3 to which the fifth subframe of each transmission frame is assigned. It is preferable that signals of other broadcasting stations are not arranged at the assigned time slot positions. Further, even if there is no broadcast station signal to be stored in the time slot, the time slot is preferably not replaced by another broadcast station signal.

  The transmission frames from the first line to the kth line are periodically repeated. Thereby, it can be considered that the sub-frames 1-1, 2-1, 3-1,. The same applies to other time slots. Here, subframes 1-2, 2-2, 3-2,..., K-2 are assigned a plurality of subframes in the same transmission frame. Since two fixed-length subframes are used, a band twice that of ch1 and ch3 can be guaranteed. By assigning a plurality of subframes, a broadcast signal with a larger encoding rate can be distributed. In other words, when the information rate that can be realized by one time slot allocation is 30 Mbps, two subframes are allocated in ch2 of FIG. 4, so that delivery at a fixed information rate of 60 Mbps is guaranteed. It becomes. Therefore, when it is desired to distribute a higher quality broadcast signal, it can be realized by acquiring a plurality of subframes corresponding to the rate of the signal to which the allocated time slot is desired to be distributed.

  FIG. 5 is a configuration diagram illustrating an example of a multiplexing device according to the present embodiment. The multiplexing device 13 according to the present embodiment performs a multiplexing process on a transmission frame for broadcast distribution. A plurality of broadcast signal input units 31, a subframe generation unit 34, a table storage unit 36, and a subframe multiplexing unit 38 are provided. In the present embodiment, the multiplexer 13 further includes a plurality of time slot (TS) storage processing units 32, a plurality of L2 processing units 33, a subframe extraction unit 35, a scheduler 37, and an overhead (OH) insertion unit 39. An example including the L2 processing unit 40 and the signal output unit 41 will be described. In this embodiment, the subframe multiplexing unit 38, the subframe extracting unit 35, the scheduler 37, and the OH inserting unit 39 constitute a multiplexing unit 27. In the present embodiment, an example in which the same number of broadcast signal input units 31 to 31-M, TS storage processing unit 32, and L2 processing unit 33 as the number of channels will be described. Also,

  Broadcast signal input units 31-1 to 31-M input broadcast signals of a plurality of channels. For example, when distributing broadcast signals of M channels, transmission signals transmitted from broadcast stations are respectively input to the M broadcast signal input units 31-1 to 31-M. For example, a broadcast signal from the broadcast station ch1 is input to the broadcast signal input unit 31-1, and a broadcast signal from the broadcast station ch2 is input to the broadcast signal input unit 31-2 as needed. Broadcast signals input to the broadcast signal input units 31-1 to 31-M are multiplexed in time to form a transmission frame.

  The TS storage processing unit 32 stores the broadcast signal input to the broadcast signal input unit 31 in the MAC packet. When the broadcast signal is a TS (Transport Stream Packet) packet, the TS storage processing unit 32 performs a storage process from the TS packet to the MAC packet. The storage process is performed with reference to the clock 30 of the multiplexing device according to the present embodiment. The process of storing the TS packet in the MAC packet may be inside or outside the multiplexing device as long as the clock of the multiplexing device according to the present embodiment can be referred to. In the case of outside the multiplexing device, the broadcast signal input unit 31 is arranged in the preceding stage of the L2 processing unit 33.

  The L2 processing unit 33 determines the destination of the packet based on the data in the data link layer and transfers the packet. If the TS storage processing unit 32 performs storage processing on the MAC packet, the L2 processing unit 33 performs MAC processing. The L2 processing unit 33 outputs the MAC packet subjected to the MAC processing to the subframe multiplexing unit 38. At this time, the L2 processing unit 33 also describes the broadcast station ID number corresponding to the channel number.

  The subframe generation unit 34 generates a subframe having a predetermined capacity. The predetermined capacity may be a fixed capacity, that is, a fixed length, or may be different for each subframe. Moreover, it may differ between transmission frames. It is preferable to generate a train of subframes in which the intervals between the subframes constituting the transmission frame of the present embodiment are almost equal. When the subframe is a MAC, a fixed-length MAC packet is generated. Moreover, it is preferable that a sequence number is given to the subframe. When the transmission capacity is 10 Gbps, the subframe generation unit 34 generates a subframe train having a speed of 10 Gbps.

  The subframe extraction unit 35 extracts individual subframes from the plurality of subframes generated by the subframe generation unit 34. Here, the subframes constituting the transmission frame are given a sequence number, and based on this, it is determined which subframe of the subframe train, for example, the broadcast signal from which broadcast station is stored in the time slot position. Is done.

  The table storage unit 36 stores a channel information table that allocates a predetermined number of subframes for each channel in a predetermined order. For example, a sequence number is assigned to a subframe constituting a transmission frame, and which broadcast signal input units 31-1 to 31-M are assigned to which subframe of the subframe train, for example, a time slot position, based on the sequence number. Information on whether to store broadcast signals from is stored in the channel information table.

  The scheduler 37 manages the schedule when the broadcast signals are multiplexed. For example, the scheduler 37 refers to the channel information table stored in the table storage unit 36, and determines whether the broadcast signal of the channel corresponding to the sequence number assigned to the subframe is stored in the subframe to the subframe multiplexing unit 38. Instruct.

  The subframe multiplexing unit 38 stores the broadcast signal input to the broadcast signal input unit 31 in the subframe generated by the subframe generation unit 34 according to the channel information table stored in the table storage unit 36. In this embodiment, since the multiplexing device 13 includes the L2 processing unit 33 and the scheduler 37, the subframe multiplexing unit 38 receives the broadcast signal input from the L2 processing unit 33 of each channel according to the instructions of the scheduler 37. Are stored in the time slot. By changing the number of allocated subframes for each channel, a bandwidth corresponding to the number of subframes can be guaranteed.

  The OH insertion unit 39 adds overhead information for each transmission frame. Overhead information is, for example, information about subframes in which broadcast signals are stored. Thus, the transmission frame described with reference to FIG. 4 is configured.

  The L2 processing unit 40 determines the destination of the packet based on the data in the data link layer and transfers the packet. For example, MAC processing is performed. The L2 processing unit 40 outputs the transmission frame according to the present embodiment to the signal output unit 41. The signal output unit 41 distributes the transmission frame according to the present embodiment to the viewer over an asynchronous packet network. Here, in this embodiment, as described with reference to FIGS. 3 and 4, a plurality of transmission frames are time-multiplexed and distributed.

  FIG. 6 is a configuration diagram illustrating an example of the separation device according to the present embodiment. The separation device 14 according to the present embodiment separates a transmission frame in which broadcast signals of a plurality of channels are time-multiplexed. The separation device 14 includes a control signal input unit 42, a transmission frame input unit 51, a frame analysis unit 44, and a subframe read control unit 47. The separation apparatus 14 further includes an L2 processing unit 52, an authentication processing unit 43, a subframe accumulation control unit 45, a subframe buffer 48, a counter 46, a TS reconstruction unit 49, a timing processing unit 50, An example including the signal output unit 53 will be described.

  The transmission frame input unit 51 receives the transmission frame according to the present embodiment. A plurality of time-multiplexed transmission frames input to the transmission frame input unit 51 are determined by the L2 processing unit 52 based on data link layer data. When the transmission frame is composed of MAC frames, the L2 processing unit 52 performs MAC processing. After performing the L2 processing, the separation unit 28 analyzes the frame, that is, analyzes which broadcast station signal is multiplexed in which subframe.

  The frame analysis unit 44 analyzes the frame format of the transmission frame input to the transmission frame input unit 51. For example, the channel information table stored in the table storage unit 36 is referenced to analyze which subframe is stored for each channel. Then, the subframe or time slot in which the channel input to the control signal input unit 42 is stored is specified. A control signal for channel selection from the viewer is sent to the frame analysis unit 44 after the authentication process, and is given as information for separating the broadcast signal.

  The table storage unit 36 stores a channel information table that allocates a predetermined number of subframes for each channel in a predetermined order. By referring to the channel information table, the column number of the subframe shown in FIG. 4 and the channel number assigned to the column number are acquired. For example, the fact that ch2 is assigned to the subframes in the third and fourth columns is acquired.

  Here, the channel information table may be an information table in which the selected channel is associated with the broadcast station ID. In this case, the channel selection information specified by the control signal input to the control signal input unit 42 is converted as a broadcasting station ID. Therefore, in this case, the frame analysis unit 44 analyzes which subframe is the broadcasting station ID.

  The control signal input unit 42 receives a control signal designating a specific channel. The control signal is a signal for channel selection from the viewer. The separation device 14 according to the present embodiment preferably further includes an authentication processing unit 43 that performs authentication of the control signal. In this case, it is authenticated whether the control signal input from the control signal input unit 42 is from a registered regular viewer. In authentication, a password, an IC card, or biometric information can be used.

  The subframe readout control 28 reads out the broadcast signal stored in the subframe of the channel designated by the control signal input to the control signal input unit 42 according to the analysis result of the frame analysis unit 44. For example, when ch2 is designated by the control signal, the broadcast information stored in the subframes in the third and fourth columns shown in FIG. 4 is read with reference to the channel information table.

  The subframe accumulation control unit 45 separates the subframe in which the broadcast signal of the selected channel is stored based on the analysis processing result of the frame analysis unit 44. Then, the subframe accumulation control unit 45 writes the broadcast signal stored in the read subframe to the subframe buffer 48. The subframe buffer 48 accumulates broadcast signals stored in subframes separated by the subframe accumulation control unit 45. At this time, since the subframe arrives at the cycle of the transmission frame, for example, at the interval of 400 μsec described in FIG. 1, the cycle of the transmission frame is counted by the counter 46. Then, the subframe read control unit 47 reads the broadcast signal stored in the subframe from the subframe buffer 48 based on the count of the counter 46.

  In the separation device 14, the broadcast signal preferably includes time slot information indicating a time slot interval in the broadcast signal. For example, time slot information is stored in the header of a subframe. In this case, it is preferable that the separation device 14 includes a time slot reconstruction unit 49. The time slot reconstruction unit 49 assigns the broadcast signal read by the subframe read control unit 47 to each time slot according to the time slot information. As a result, it can be reconstructed into a TS packet sequence transmitted from the broadcasting station. At that time, the timing processing unit 50 adjusts the timing of the interval between TS packets and generates the timing at that timing. Finally, it is sent to the signal output unit 53. The signal output unit 53 outputs the transmitted TS packet signal.

  As described above, the packet network, which is an asynchronous network according to the present embodiment, has a flexible frame format and uses a transmission frame that is periodically repeated. It becomes possible to broadcast a fine video signal.

  FTTH (Fiber-To-The-Home) can be used in the broadcast industry that distributes broadcast signals.

1 is a schematic configuration of a system for distributing a transmission format according to a first embodiment. It is a schematic structure of the system which delivers the transmission format which concerns on Embodiment 2. FIG. 2 schematically shows a transmission frame format according to the present embodiment. It is an example of the sub-frame multiplexed on the transmission frame. It is a block diagram which shows an example of the multiplexing apparatus which concerns on this embodiment. It is a block diagram which shows an example of the separation apparatus which concerns on this embodiment. It is a schematic diagram which shows an example of the conventional broadcast signal, (a) shows arrangement | positioning of the frequency in terrestrial digital broadcasting, (b) shows the band wave in a general transmission. It is a schematic block diagram which shows the delivery form by the conventional IP broadcast. It is an example of the flow when receiving broadcast distribution using IP.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Network 11a, 11b, 11c Distribution server 12 Terminal device 13 Multiplexer 14 Separation device 21, 21a, 21b Multicast router 22 Receiver 23 Head end 24a, 24b Accommodating station 25a, 25b Transmission device 26 Termination device 27 Multiplexer 28 Separation unit 30 clocks 31-1, 31-2, 31-3 broadcast signal input unit 32 TS storage processing unit 33 L2 processing unit 34 subframe generation unit 35 subframe extraction unit 36 station information table 37 schedule 38 subframe multiplexing unit 39 OH information Insertion unit 40 L2 processing unit 41 Signal output unit 42 Control signal input unit 43 Authentication processing unit 44 Frame analysis unit 45 Subframe accumulation control unit 46 Counter 47 Subframe read control unit 48 Subframe buffer 49 TS reconstruction unit 50 Timemin Processing unit 51 transmission frame input unit 52 L2 processing unit 53 signal output unit 100-1, 100-2, 100-m broadcast signal 101-1, 101-2, 101-3, 101-4, 101-5, 101 -6, 101-7 Packet 102, 103-1, 103-2, 103-3, 101-N Time slot 110-1, 110-2, 110-k Transmission frame

Claims (9)

A transmission frame format for distributing broadcast signals of a plurality of channels over an asynchronous packet network,
A transmission frame of a predetermined capacity is periodically repeated,
The transmission frame comprises more subframes than the number of channels;
A transmission frame format characterized in that the number of subframes allocated to a channel is variable.   The transmission frame format according to claim 1, wherein the transmission frame includes a plurality of fixed-length subframes.   The transmission frame format according to claim 1 or 2, wherein the broadcast signal is stored in a predetermined subframe in the transmission frame. A transmission method for distributing broadcast signals of a plurality of channels over an asynchronous packet network,
Periodically repeat a transmission frame of a predetermined capacity,
The transmission frame comprises more subframes than the number of channels;
A transmission method characterized in that the number of subframes assigned to a channel is variable.   The transmission method according to claim 4, wherein the transmission frame includes a plurality of fixed-length subframes.   The transmission method according to claim 4 or 5, wherein the broadcast signal is stored in a predetermined subframe in the transmission frame. A subframe generating unit for generating a subframe of a predetermined capacity;
A broadcast signal input section for inputting broadcast signals of a plurality of channels;
A table storage unit for storing a channel information table for assigning a predetermined number of subframes for each channel in a predetermined order;
A subframe multiplexing unit that stores the broadcast signal input to the broadcast signal input unit in the subframe generated by the subframe generation unit according to the channel information table;
A multiplexing apparatus comprising: A separation device for separating a transmission frame in which broadcast signals of a plurality of channels are time-multiplexed,
The transmission frame is
A plurality of subframes having a predetermined capacity are time-multiplexed,
A predetermined number of the subframes for each channel are allocated in a predetermined order;
A table storage unit for storing a channel information table for assigning a predetermined number of subframes for each channel in a predetermined order;
A control signal input unit to which a control signal designating a specific channel is input;
A transmission frame input unit to which the transmission frame is input;
A frame analysis unit for analyzing a frame format of the transmission frame input to the transmission frame input unit;
A subframe reading control unit that reads a broadcast signal stored in a subframe of a channel specified by the control signal input to the control signal input unit, according to an analysis result of the frame analysis unit;
A separation apparatus comprising: The broadcast signal includes time slot information indicating a time slot interval,
9. The separation apparatus according to claim 8, further comprising a time slot reconfiguration unit that reconfigures the broadcast signal read by the subframe read control unit according to the time slot information.

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