JP7045254B2 - In-building transmission system, optical receiver, encapsulation device, and decapsulation device - Google Patents

Description

The present invention relates to an in-building transmission system, an optical receiver, an encapsulation device, and a decapsulation device, and in particular, an in-building transmission system in a cable television using an IP (Internet Protocol) signal and an optical receiver constituting the same. , Encapsulation device, and decapsulation device.

Currently, cable television provides broadcasting services such as terrestrial / satellite broadcast retransmission, community channel broadcasting, and multi-channel broadcasting, as well as various communication services such as Internet connection, telephone, and VOD (Video On Demand).

When the cable TV station to the subscriber is an HFC (Hybrid Fiber Coaxial) transmission line, the transmission method of the broadcasting service is 64QAM (Quadrature Amplitude Modulation) or transmodulation method that remodulates with 256QAM, frequency conversion pass-through method, The pass-through method is used. In the case of communication services, the DOCSIS3.0 (Data Over Cable Service Interface Specifications 3.0) standard for transmitting an IP signal as an RF (Radio Frequency) signal is in operation (Non-Patent Documents 1 and 2). These broadcast and communication signals have a bandwidth of 6 MHz per wave and are frequency-multiplexed in the frequency band of 90-770 MHz. Then, the optical fiber is transmitted by the SCM (Sub Carrier Multiplexing) transmission method in which the light is analog-intensity modulated by the voltage of the RF signal whose frequency is multiplexed, converted into an electric signal on the way, and the distribution system is transmitted by the coaxial cable. .. However, the total transmission capacity of this transmission method is about 3-4 Gbps, and it is said that the band is tight.

On the other hand, some cable TV operators may use an FTTH (Fiber to the Home) system. In this case, not only the 90-770 MHz band but also the BS-IF (Intermediate Frequency) band can be frequency-multiplexed and transmitted by the SCM transmission method, so that a total transmission capacity of about 4-6 Gbps can be used for broadcasting services. Is. The communication service is not multiplexed with SCM, but is transmitted as a signal of another wavelength by a transmission method such as G-EPON (Gigabit Ethernet Passive Optical Network) as an IP signal with digital light intensity modulation.

As mentioned above, it has already been said that the bandwidth of cable TV that uses a coaxial cable for the distribution system is tight, and in the case of FTTH, it is thought that there is still room for the broadcasting service band, but in the future, 4K. At the stage when 8K (Super Hi-Vision) services become widespread, it is considered necessary to further increase the capacity even in the case of FTTH transmission lines.

As a method to realize large-capacity transmission in FTTH, instead of transmitting by analog intensity modulation of light with the RF signal used in the current cable TV, light is digitally intensity-modulated with a baseband signal as in the communication system. (Patent Document 1) has been studied. As a baseband optical transmission technology for communication, 10G-EPON (Non-Patent Document 3) capable of large-capacity transmission of 10 Gbps was standardized in 2009, and compatible products have also been commercialized. Broadcasting systems also utilize 10G-EPON downlink transmission line coding, and by time-dividing and multiplexing video signals and transmitting them in the baseband as IP signals, there is a possibility that large-capacity signals can be transmitted optically at low cost. There is.

By the way, when a cable TV operator makes a transmission line optical (optical fiber), it is relatively easy to make each subscriber optical in the case of a detached house, and a baseband transmission method can be introduced. .. However, the transmission lines in the building of apartments such as condominiums are not under the jurisdiction of cable TV operators, and it is difficult to make each subscriber optical. Many of the transmission lines in the building have only transmission lines such as coaxial cables or telephone lines, and there is no space to lay new cables, and the procedure for lightening work is complicated, so it takes time and money to make lighting. Requires.

In the case of the SCM transmission method using conventional analog optical intensity modulation, the optical signal is converted to an RF signal by O / E (optical / electrical) conversion with a V-ONU (Video Optical Network Unit) in front of the coaxial cable, and inside the building. Is transmitted by an electric signal. However, in the case of the baseband transmission method in which digital light intensity modulation is performed, it is difficult to transmit the O / E converted baseband signal as it is because the high frequency component is greatly attenuated. Therefore, a means for transmitting a large-capacity baseband signal in the transmission line in the building is required.

As a means for realizing this, a cable television operator is studying IP broadcasting using a transmitter / receiver compatible with the DOCSIS 3.0 standard for communication (Non-Patent Document 4). This installs a CMTS (Cable Modem Termination System) or CMC (Coax Media Converter), which is a transmission device, at a point in the middle of the transmission path where an optical fiber changes to a coaxial cable, and multicasts the IP signal to the CM (Cable Modem) in the house. It is transmitted by. Using the channel bonding technology in the DOCSIS 3.0 standard, it is possible to bond 256QAM signals to 8 channels and transmit a large capacity of about 300 Mbps. Further, the CM can dynamically change the bonding group to be received by DBC (Dynamic Bonding Change), and can also receive a channel in another bonding group.

This DOCSIS 3.0 standard compliant CMTS is installed in the apartment, and CM is installed in each receiver (subscriber)'s house to transmit 4K / 8K signals by IP multicast. A system (delivery method) is being considered.

One is a method of dynamically switching transmission programs using channel bonding and performing IP multicast transmission of the programs. Based on FIG. 9, a first in-building transmission system and a distribution method thereof, which have been conventionally studied, will be described. FIG. 9 shows a program that arrives at an apartment house (apartment or the like) via an optical fiber until it is delivered to each receiver's house. The in-building transmission system includes an optical receiver 91, CMTS92, and CM931 to 942. The optical receiver 91 to CM931 to 942 are connected by a coaxial cable.

The optical receiver 91 receives program data (for example, a baseband signal) of all programs delivered via an optical fiber (not shown), converts it into an electric signal, and converts the requested program into an IP signal. Is output to CMTS92.

The CMTS 92 associates a channel receivable by a receiver with the requested program data, and further combines the channels to form a bonding group consisting of a plurality of channels (a group of bonded channels; hereinafter, simply referred to as "bonding". )make. In the figure, one black trapezoid indicates one channel, for example, it is composed of a signal of 256QAM having a predetermined carrier frequency, and is frequency-multiplexed and transmitted. When there is a request for an 8K ₁ program via CM931 of group 1, the data of the 8K ₁ program is associated with the channel of bonding 1.

The CM931 to 942 are installed in each receiver's house, receive a predetermined bond, demodulate and decode the channel signal, and generate a video stream of the program. In this case, since the number of bonds that can be received is limited by the number of CM tuners, a plurality of service groups 93 and 94 consisting of a small number of households (recipients' homes) are created, and multicast is performed within each group. CMs within each service group receive a fixed bonding channel. For example, CM931,932 of group 1 receives bonding (channel) 1, and CM941,942 of group 2 receives bonding 2. When there is a program viewing request from CM931 to 942 to CMTS92, CMTS92 dynamically changes the program transmitted by each bonding. Assuming that the number of CM tuners is 8 and all 8 channels are 256QAM transmission, the transmission capacity is about 300 Mbps, and this band is shared by households in the service group.

Another method using the DOCSIS3.0 standard is a method of performing IP multicast transmission while changing the bonding (channel) received by using DBC. Based on FIG. 10, a second in-building transmission system and a distribution method thereof, which have been conventionally studied, will be described. The in-building transmission system of FIG. 10 includes an optical receiver 91, a CMTS92, and CM95 to 98. The optical receiver 91 to CM95 to 98 are connected by a coaxial cable.

The optical receiver 91 receives program data (for example, a baseband signal) of all programs delivered via an optical fiber (not shown), converts it into an electric signal, and converts the requested program into an IP signal. Is output to CMTS92.

The CMTS 92 associates a channel with program data to be transmitted, and further combines the channels to form a bond composed of a plurality of channels. In this case, the correspondence between the program and the channel for transmitting the program is preset.

The CMs 95 to 98 are installed in each receiver's home, receive desired bonding (channels), demodulate and decode channel signals, and generate a video stream of a program. Each CM changes the bonding received according to the viewing request, not the fixed bonding. For example, when CM 1 (95) watches program 1 (8K ₁ ), it receives bonding 1, and when it watches program 2 (8K ₂ ), it receives bonding 2. The same applies to other commercials. Therefore, when the same program is viewed at a plurality of subscribers' homes, it can be efficiently transmitted by multicast.

Japanese Unexamined Patent Publication No. 2016-152539

CableLabs DOCSIS 3.0 specifications JCTEA STD-024-1.0 "CATV high-speed data transmission device DOCSIS 3.0" IEEE edition, "IEEE Std 802.3av-2009" Ministry of Internal Affairs and Communications Press Material 4 Study Group on the Ideal Way of Cable TV Video Distribution for the 4K / 8K Era Material 1-4 "Current Situation of the Cable Industry and Concept of IP Broadcasting", (2017)

By using CMTS and CM compatible with the DOCSIS3.0 standard, 4K / 8K signals can be transmitted by IP multicast, but the two in-building transmission systems that have been studied so far have the following problems. be.

In the case of the first in-building transmission system shown in FIG. 9, when receivers (subscribers) of different service groups request viewing of the same program, the same signal is transmitted by a plurality of bonds (for example,). Program 8K ₁ is transmitted simultaneously by bonding 1 and bonding 2), and the band cannot be used effectively. Since the transmission capacity of 8K is about 100 Mbps, for example, if the same 8K program is transmitted by bonding at about 300 Mbps, 1/3 of the band is wasted.

In the case of the second in-building transmission system shown in FIG. 10, in order to perform DBC by a program viewing request (IP multicast join signal) from CM, which program is transmitted to which bonding (channel) in advance. It is necessary to know, and it is necessary to fix each bonding and the IP address of the program to be transmitted and transmit by multicast. That is, it is necessary to set in advance that a certain bonding transmits a packet of this IP address, and this setting cannot be dynamically changed by the existing DOCSIS standard. In this case, in order for the receiver (subscriber) to be able to select all the programs, the CMTS needs a transmission capacity that can always transmit all the programs regardless of the number of households. Alternatively, the number of programs that can be viewed is limited by the upper limit of the transmission capacity.

In the in-building transmission system that has been conventionally studied in this way, the bandwidth is wasted and the number of programs is limited, so that a more efficient distribution method is required. Specifically, there is a demand for a means for efficiently distributing a program on a coaxial cable whose band is limited as compared with an optical fiber.

Therefore, the present invention has been made in view of such a situation, and an object of the present invention is to use a coaxial cable and a transmission / reception device for communication, which are widely used as transmission lines in buildings of apartment houses (apartments, etc.). We provide an in-building transmission system that can be utilized and enables more efficient transmission of 4K / 8K multi-channel signals, and an optical receiver, encapsulation device, and deencapsulation device that compose the transmission system. There is something in it.

In order to solve the above problems, the in-building transmission system according to the present invention is an in-building transmission system that transmits a broadcast signal in a cable television transmitted by an optical signal as an electric signal in the building, and transmits an IP packet of a program. An optical receiver that receives an optical signal including it, converts it into an electric signal, encapsulates the IP packet of the program requested for viewing by an IP address for distribution, and outputs the encapsulated IP packet for distribution. It is equipped with CMTS (Cable Modem Termination System) that is transmitted in the channel of RF (Radio Frequency) signal that is orthogonal phase amplitude modulated based on the IP address, and each receiver has the channel in CM (Cable Modem). Is received, demolished, and then unencapsulated and returned to the IP packet of the original program.

Further, in order to solve the above problems, the in-building transmission system according to the present invention is an in-building transmission system that transmits a broadcast signal in a cable television transmitted by an optical signal as an electric signal in the building, and is an IP of a program. An optical receiver that receives an optical signal including a packet, converts it into an electric signal, and then outputs an IP packet of the program requested to be viewed, and the IP packet of the program requested to be viewed are encapsulated by a distribution IP address. An encapsulation device and a CMTS (Cable Modem Termination System) that transmits the encapsulated IP packet on a channel of an RF (Radio Frequency) signal that has been quadrature phase amplitude modulated based on the distribution IP address. A common feature is that each receiver receives the channel in a CM (Cable Modem), demolishes it, and then decapsulates it and returns it to the IP packet of the original program.

Further, in the in-building transmission system, it is desirable that the CMTS bonds the channels and performs multicast transmission.

Further, in the in-building transmission system, it is desirable that the CMTS and the CM comply with the DOCSIS (Data Over Cable Service Interface Specifications) standard.

Further, in the transmission system in the building, the encapsulation is performed based on the encapsulation table in which the correspondence between the program IP address and the distribution IP address is set, and the encapsulation table is updated based on the program viewing request. It is desirable to do.

In order to solve the above problems, the optical receiver according to the present invention receives an optical signal including an IP packet of a cable TV program, and outputs an IP packet of the program requested to be viewed to a CMTS (Cable Modem Termination System). An O / E conversion unit that converts the optical signal into an electric signal, a transmission path coding / decoding unit that decodes the electric signal to generate an IP packet of a program, and a decoding unit. A capsule in which a multiplexing separator that separates and outputs the IP packet of the program requested to be viewed from the IP packet of the program, a distribution IP address corresponding to the CMTS channel, and a program IP address are set. It is characterized by including an encapsulation unit that encapsulates an IP packet of a program output from the multiplexing separation unit with an IP header of the distribution IP address based on the conversion table.

Further, it is desirable that the optical receiver updates the encapsulation table based on the program viewing request.

In order to solve the above problems, the encapsulation device according to the present invention is an encapsulation device that encapsulates and outputs an IP packet of a cable TV program, and is for distribution corresponding to a channel of CMTS (Cable Modem Termination System). An encapsulation table in which the correspondence between the IP address and the program IP address is set, and a capsule that encapsulates the input program IP packet with the IP header of the distribution IP address based on the encapsulation table. It is characterized by having a chemical unit.

Further, it is desirable that the encapsulation device updates the encapsulation table based on the program viewing request.

In order to solve the above problems, the deencapsulation device according to the present invention is a deencapsulation device that receives an IP packet of an encapsulated cable TV program, and is an IP address for distribution in a CMTS (Cable Modem Termination System). Refer to the encapsulation table in which the correspondence with the program IP address is set, the multicast protocol conversion unit that converts the multicast join signal into a predetermined format compatible with the CMTS, and the encapsulation table. It is characterized by including a decapsulation unit that decapsulates the IP packet of the encapsulated program.

Further, it is desirable that the decapsulation device updates the encapsulation table based on the program viewing request.

The present invention utilizes an existing coaxial cable and a transmission / reception device for communication in a transmission line in an apartment building where only a coaxial cable is laid, and transmits a multi-channel 4K / 8K signal more efficiently than before. Make it possible.

It is an overall view of the FTTH transmission system including the in-building transmission system of this invention. It is a figure explaining the in-building transmission system of this invention and the delivery method thereof. It is a block diagram which shows the structural example of the optical receiving apparatus of this invention. It is a block diagram which shows the structural example of the decapsulation apparatus of this invention. This is an example of setting CMTS multicast used in the present invention. This is a configuration example of the encapsulation table used in the present invention. This is an example of the configuration of the encapsulation table when the address allocation is changed by the viewing request. It is a comparison diagram of the calculated value of the number of households of an apartment house and the required transmission capacity. It is a figure explaining the 1st in-building transmission system and its distribution system examined conventionally. It is a figure explaining the 2nd in-building transmission system and the delivery system which were examined conventionally.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an overall view of an FTTH transmission system in a cable television including the in-building transmission system of the present invention. In the following, a case where a baseband transmission method is introduced in the FTTH transmission line will be described as an example, but the method is not limited to the baseband transmission method and can transmit program data (IP signals) of all programs using an optical transmission line. If so, any transmission method may be used for signal transmission on the FTTH transmission line.

The FTTH transmission system shown in FIG. 1 includes one cable television station 1, an arbitrary number of detached houses 2 and apartment houses 3, and an optical transmission line 4 composed of optical fibers connecting them. The cable television station 1 includes an optical transmission device 5, converts a video signal into an optical signal, and outputs the video signal to the optical transmission line 4 by, for example, baseband transmission. The optical signal is branched (amplified and distributed) and transmitted to the receiver (subscriber)'s house or the apartment house where the receiver is located.

The detached house 2 includes an optical receiver 10, an IP-STB (Set Top Box) 50, and a TV (television) 60.

The optical receiver 10 receives program signals (for example, baseband signals) of all programs delivered via the optical transmission line 4, and performs O / E (optical / electric) conversion, decoding, channel selection, and the like. , Only the video stream (IP packet of the program) to be viewed is output to the IP-STB50. As will be described later, the optical receiving device 10 can be shared with the optical receiving device 10 used in the apartment house 3.

The IP-STB 50 requests the optical receiving device 10 for a program to be viewed, receives a video stream (IP packet of the program) from the optical receiving device 10, converts it into a signal that can be viewed on a general television, and converts it into a signal that can be viewed on a general television. Output to TV60.

Then, the receiver (viewer) can watch the desired program on the TV 60.

The apartment complex (apartment, etc.) 3 is provided with an in-building transmission system for transmitting a broadcast signal in a cable television transmitted by an optical signal as an electric signal in the building. The apartment house 3 includes an optical receiver 10 and CMTS 20 used jointly (commonly), a CM 30 (301 to 30 _n ) installed in each receiver's house, and _a decapsulation device 40 ( _{401 to 40 n )} . , IP-STB50 (501 to _{50 n} ), and TV60 (601 to 60 _{n )} .

Hereinafter, the in-building transmission system of the present invention and its distribution method will be described with reference to FIG.

The optical receiving device 10 receives a program signal (for example, a baseband signal) of all programs delivered via the optical transmission path 4, and performs O / E (optical / electric) conversion, decoding, channel selection, and the like. As will be described later, the optical receiver 10 includes an IP encapsulation processing unit 12 inside, and adds a distribution IP address (in this example, an IPv4 address) to a video stream (IP packet of a program) requested for viewing. IP encapsulation is performed, and the encapsulated signal is output to CMTS20. In the case of an apartment house, the optical receiver 10 and the CMTS 20 can be installed in a common space such as an MDF (Main Distributing Frame) room in the condominium.

The CMTS 20 associates the program data input from the optical receiver 10 with the bonding (channel) based on the distribution IP address. That is, the channel or bonding to transmit the signal of each distribution IP address is set in advance, and the program data input from the optical receiver 10 is distributed to the viewing household (CM30 at each receiver's home) by multicast. do. In the figure, one black trapezoid indicates one channel, for example, it is composed of a 256QAM signal having a predetermined carrier frequency and is transmitted as a frequency-multiplexed RF signal. Program data encapsulated by a distribution IP address is associated with each channel or bonding. The CMTS 20 outputs a multicast join signal, which is a viewing request from the receiver, to the optical receiver 10, and the optical receiver 10 controls the encapsulated IP address (IP address for distribution) to watch the program. Only transmit. As the CMTS 20, an off-the-shelf DOCSIS 3.0 standard compliant transmitter can be used.

FIG. 5 shows an example of CMTS multicast setting (that is, correspondence between bonding and distribution IP address). In this example, the CMTS 20 has a transmission capacity of 300 Mbps by bonding a 256QAM channel for 8 channels (frequency 93 to 135 MHz) as bonding 1. Using this bonding 1, it is set to transmit the program of the distribution IP address (multicast IPv4 address) from 225.0.01 to 225.0.0.6 by multicast.

Here, in order to perform large-capacity transmission, channel bonding is premised, but if the correspondence between the distribution IP address and the channel is set, the program data (encapsulated IP packet) is used independently. Channel (QAM signal) may be transmitted. Further, the transmission method is not limited to multicast, and unicast transmission may be used.

CM1 to CMn (301 to 30 _n ) are installed in each receiver's house, receive a bonding (channel) through which the program for which viewing request is transmitted is transmitted, demodulate and decode the channel signal, and perform a video stream of the program (30 ₁ to 30 n). Here, the IP packet of the encapsulated program) is generated. For example, when CM ₁ (301) watches program 8K ₁ , it receives bonding 1, and when CM ₂ (302) watches program 8K ₂ , it receives bonding 2. The IP packet of the encapsulated program obtained by demodulation / decoding is output to the decapsulation device 40. As the CM1 to CMn _{(301 to 30 n )} , an off-the-shelf DOCSIS 3.0 standard compliant receiving device can be used.

In addition to the CMTS and CM compliant with the DOCSIS 3.0 standard, those compliant with the DOCSIS 3.1 standard may be used.

The decapsulation device 40 ( _{401 to 40 n )} decapsulates the IP packet of the encapsulated program input from the CM 30. That is, the distribution IP address (IP header) is deleted from the encapsulated IP packet, returned to the original program data (program IP packet), and output to the IP-STB50. Details will be described later. The functions and operations of the IP-STB50 (501 to _{50 n} ) and the TV60 (601 to 60 _{n )} after this are the same as those of the detached house.

FIG. 3 shows a block diagram showing a configuration example of the optical receiver 10 of the present invention.

The optical receiver 10 includes a transmission line decoding / multiplex separation unit 11 and an encapsulation processing unit 12. Further, in order to enable the optical receiver 10 to be shared between the detached house and the apartment house, the flow of the video stream is changed between the time of transmission in the detached house and the time of transmission in the building in the apartment house. The distribution route control units 13 and 14 to be controlled can be provided. When the optical receiving device 10 is dedicated to the transmission system in the building, the distribution route at the time of detached transmission is unnecessary, and the distribution route control units 13 and 14 may be omitted. The transmission line decoding / multiplex separation unit 11 has an O / E conversion unit 111, a transmission line coding / decoding unit 112, and a multiplexing separation unit 113, and the encapsulation processing unit 12 is a capsule. It has a conversion table 100 and an IPv4 / IPv6 encapsulation unit 121. The functions of each block will be described below.

The O / E (optical / electric) conversion unit 111 converts an optical signal transmitted from the optical transmission device 5 (for example, program data transmitted in the base band) into an electric signal, and the transmission line coding / decoding unit 112 converts it into an electric signal. Output.

The transmission line coding / decoding unit 112 decodes the transmission line coding performed on the transmission side for the transmission data that has become an electric signal. The processing here includes, for example, performing deinterleaving processing on the interleaving performed on the transmitting side, performing error correction processing, and the like. All the decoded program data (program IP packets) are output to the multiplexing / separation unit 113.

The multiplexing separation unit 113 separates and outputs the video stream selected based on the program viewing request from the IP-STB of the receiver (subscriber) to the video stream of all the decoded program data. Here, at the time of detached transmission, the distribution route control units 13 and 14 directly output the signal (IPv6 video stream) output from the multiplexing / separation unit 113 as the output of the optical receiver 10. On the other hand, at the time of transmission in the building, the video stream separated by channel selection is output to the encapsulation processing unit 12.

The encapsulation processing unit 12 encapsulates the separated video stream (IP data of the program) in the IPv4 / IPv6 encapsulation unit 121 and then outputs it. Specifically, the IP packet of the program (video signal) for which viewing request is requested is IP-encapsulated and output by the IP header of the distribution IP address set so that it can be transmitted by the CMTS in the subsequent stage. The IP address for distribution to be encapsulated is determined with reference to the encapsulation table 100. When a program that has not been viewed or a program that is newly viewed is requested, the encapsulation table 100 is updated to control the program to be distributed.

FIG. 6 shows a configuration example of the encapsulation table 100. Since programs 1 (8K) to program 6 (4K) are being viewed, the original IP address of these programs (sometimes referred to as the program IP address. In this example, the IPv6 address) is used as the distribution IP address (this). In the example, it is encapsulated by IPv4 address). The distribution IP address corresponds to the channel or bonding transmitted by CMTS. If the receiver stops watching program 6 and starts watching program 8 (4K), the encapsulation table is updated as shown in Fig. 7 (Distribution IP address 225.0.0.6, the original IP address of program 8). By updating to correspond to FF02 :: 08), it is possible to change the program to be transmitted without changing the CMTS setting.

In the examples of FIGS. 2 and 3, the encapsulation is performed by the IPv4 header because it is assumed that the CMTS in the subsequent stage supports only IPv4. In this case, the IPv4 header is used. Encapsulate. If the CMTS in the subsequent stage supports IPv6 multicast, it is encapsulated in the IPv6 header. If only unicast can be transmitted, it is encapsulated in IPv4 / IPv6 unicast. All transmission of program IP packets follow the CMTS settings and encapsulation table settings.

Further, the optical receiving device 10 may be used integrally with the CMTS 20. Further, the optical receiver has been described as a baseband optical receiver (data downlink dedicated device), but this is referred to as another IP signal receiver, for example, a 10G-EPON receiver (data downlink and uplink compatible device). The encapsulation processing unit 12 may be installed in the 10G-EPON receiving device and connected to the CMTS of the in-building transmission system.

Further, the optical receiving device of FIG. 3 may be separately configured as an optical receiving device including a transmission line decoding / multiplex separation unit 11 and an encapsulation device including an encapsulation processing unit 12 (not shown). ). At this time, the optical receiving device receives the optical signal including the IP packet of the program, converts it into an electric signal, and then outputs the IP packet of the program requested for viewing (IPv6 video stream in FIG. 3) to the encapsulation device. The encapsulation device encapsulates the IP packet of the program requested for viewing with the distribution IP address based on the encapsulation table, and outputs it to the CMTS in the subsequent stage.

FIG. 4 shows a block diagram showing a configuration example of the deencapsulation device 40 of the present invention.

The decapsulation device 40 includes a multicast protocol conversion unit 41, an IPv4 / IPv6 decapsulation unit 42, and an encapsulation table 100. The encapsulation table 100 is the same as the encapsulation table 100 of the optical receiver 10, and is updated in synchronization with the optical receiver 10.

The procedure of the operation of the multicast protocol conversion unit 41 and the synchronous update of the encapsulation table 100 is as follows. When the multicast join signal, which is a program viewing request, comes from the IP-STB 50, the multicast protocol conversion unit 41 unicasts and transmits the information of the program viewing request and the IP address of the viewing request program to the optical receiver 10. Based on the information from the decapsulation device 40, the optical receiver 10 updates its own encapsulation table 100 so as to transmit the bonding QAM signal having a free band. Then, the update information of the encapsulation table is transmitted to each decapsulation device 40 ( _{401 to 40 n )} , and the encapsulation table 100 of all the decapsulation devices 40 is updated. The decapsulation device (multicast protocol conversion unit 41) transmits a program viewing request (multicast join signal) in which the original IP address of the program is changed to the distribution IP address to the optical receiver 10 based on the updated encapsulation table 100. do. At this time, if CMTS is IPv4 compatible, it is converted to IGMP (Internet Group Management Protocol), and if it is IPv6 compatible, it is converted to MLD (Multicast Listener Discovery) and output. At this time, IGMPv2 or MLDv1 that does not need to specify the source address is used.

Then, the IPv4 / IPv6 decapsulation unit 42 identifies the IPv6 / IPv4 encapsulated video packet input from the CM with reference to the encapsulation table 100, deencapsulates the packet, and releases the original video signal (original IP address). It returns to the IP packet of the program it has) and outputs it to the IP-STB50 and TV60. The deencapsulation device 40 may be incorporated as a deencapsulation unit in the CM 30 or the IP-STB 50. In this example, it is assumed that the data encapsulated in the IPv4 header is input, but if the CMTS20 supports IPv6, the data encapsulated in the IPv6 header is input, and this IPv6 header is deleted and the original. You can return to the program data of.

The transmission procedure in the in-building transmission system of the present invention will be briefly described with reference to FIG. 2 and the like.

(1) In CMTS20, the correspondence between the distribution IP address and the transmission channel or bonding is preset.

(2) A viewing request for a program (for example, program 1: 8K ₁ ) from the IP-STB at the receiver's home is transmitted to the optical receiver 10 via the deencapsulation device ₁ (401).

(3) The correspondence between the distribution IP address and the original IP address (program IP address) of the program requested to be viewed is set in the encapsulation table. For example, the original IP address of the program 1 is set to correspond to the distribution IP address of the bonding 1. This setting is reflected in all of the encapsulation tables of the IP encapsulation processing unit 12 and the decapsulation devices ₁ to n (401 to 40 _n ).

(4) In the optical receiving device 10, the requested IP packet of the program 1 is encapsulated in the IP header of the distribution IP address of the bonding 1 and output according to the setting of the encapsulation table.

(5) The CMTS 20 transmits the encapsulated IP packet of the program 1 by the bonding 1, and instructs the CM ₁ (301) to receive the bonding 1.

(6) CM1 (301) receives program ₁ (8K ₁ ) by bonding 1.

(7) The decapsulation device ₁ (401) restores the encapsulated packet and outputs the video data (8K ₁ ) of the program 1.

In this way, encapsulation can be used to transmit all programs on a small number of channels.

(Verification of effect)
In order to confirm the effect of the transmission system in the building explained above, we will verify using specific numerical values.

First, as condition settings, 30 households are assumed to be the number of condominiums, 100 programs are 2K (10 Mbps), 18 programs are 4K (40 Mbps), and 1 program is 8K (100 Mbps) as a program to transmit FTTH. It is assumed to be 8.8 Gbps. Each household can watch up to two programs at the same time. The CMTS used is a 256QAM signal (38 Mbps), which is transmitted by maximum 8-channel bonding and outputs a QAM signal of 32 channels per card. The transmission capacity per bonding group is about 300 Mbps at 38 Mbps x 8 channels. The transmission capacity per card is 38 Mbps x 32 = 1216 Mbps. The CM receives signals bonded by eight multi-tuners. When performing DBC, the video is transmitted on the secondary channel 7ch other than the primary channel 1ch, and the secondary channel is switched by the DBC.

The case where the first conventional transmission system (FIG. 9) is used is verified. When transmitting 1 program of 8K and 5 programs of 4K, a transmission capacity of 300 Mbps is required. Considering that 3 households can watch 6 programs at the same time, 3 households are accommodated per 1 bonding group (300 Mbps). Since multicast cannot be performed between different service groups, 10 bonding groups are required for 30 households. Therefore, an 80ch 256QAM signal (3 Gbps) is required.

The case where the second conventional transmission system (FIG. 10) is used is verified. The only way to make it possible for each household to select all programs is to transmit all programs. Dividing all programs (1.8 Gbps) by 38 Mbps / channel gives 48 channels. If 2ch is the primary channel and the remaining 48ch is the secondary channel, a 256QAM signal (about 1.9 Gbps) of 50 channels is required. However, it is an approximate value and is calculated on the assumption that the total transmission capacity of a plurality of programs fits in the bonding group accurately.

The case where the in-building transmission system (FIG. 2) of the present invention is used will be verified. In this case, since multicast transmission is possible, it is sufficient to design with the maximum transmission capacity at the time of simultaneous viewing. There are 30 households, and considering simultaneous viewing of up to 2 programs in each household (60 programs in total), 8K1 program (100 Mbps) + 4K18 program (40 Mbps x 18) + 2K41 program (10 Mbps x 41) = 1230 Mbps. If the maximum transmission capacity (1230 Mbps) at the time of simultaneous viewing is divided by 38 Mbps / channel, it becomes 33 channels. If 2ch is the primary channel and the remaining 33ch is the secondary channel, a 256QAM signal (about 1.3 Gbps) of 35ch is required.

As described above, it can be seen that the in-building transmission system of the present invention can transmit with a smaller transmission capacity than the conventional transmission system. In this example, each household can select up to two programs at the same time. Further, in the case of the present invention, when each household watches the same program, it can be efficiently transmitted by multicast, and the free band can be effectively used for data communication or the like.

FIG. 8 shows a comparison between the number of households in an apartment house and the calculated value of the required transmission capacity. The horizontal axis is the number of recipient households, and the vertical axis is the transmission capacity required for the transmission line in the building.

Since the first conventional transmission system (conventional system 1) requires a transmission capacity of 300 Mbps for every three households, it can be seen that the required transmission capacity increases linearly according to the number of households. Further, it can be seen that in the second conventional transmission system (conventional system 2), the transmission capacity for all programs is always required regardless of the number of households. In the case of the present invention, since the transmission capacity of the number of households × the band of the viewing program × 2 is required, the required transmission capacity gradually increases according to the number of households. Since a band for transmitting all programs is required in about 50 households, the graph is the same as that in the conventional system 2 in the case of 50 households or more. Therefore, in the case of 50 households or less in this example of the number of programs, the in-building transmission system of the present invention can efficiently transmit programs to each household with a smaller transmission capacity than the conventional system, and all programs can be selected. It turns out that it can be.

As described above, when the base band transmission method is introduced into the FTTH system of the cable television, the present invention solves the problem of establishing an efficient transmission means of 4K / 8K multi-channel signals in the transmission line in the building such as an apartment. Is a method that can solve this problem.

In the above embodiment, the configuration of the transmission system in the building has been described, but the present invention is not limited to this, and is configured as a transmission method for transmitting program data using a coaxial cable in an apartment house. May be good. That is, it may be configured as a transmission method for transmitting program data (IP packet of a program) to a plurality of receivers by using IP multicast transmission according to the data flow of FIG.

Although the above embodiments have been described as typical examples, it will be apparent to those skilled in the art that many modifications and substitutions can be made within the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited by the above-described embodiments, and various modifications and modifications can be made without departing from the scope of claims. For example, it is possible to combine the plurality of constituent blocks described in the embodiment into one, or to divide one constituent block into one.

1 Cable TV station 2 Detached house 3 Apartment house 4 Optical transmission line 5 Optical transmission device 10 Optical receiver 11 Transmission line decoding / multiplex separation unit 12 Encapsulation processing unit 13, 14 Distribution route control unit 20 CMTS
30 CM
40 Decapsulation device 41 Multicast protocol conversion unit 42 IPv4 / IPv6 decapsulation unit 50 IP-STB
60 TV
91 Optical receiver 92 CMTS
93,94 Service Group 95-98 CM
100 Encapsulation table 111 O / E conversion unit 112 Transmission path coding / decoding unit 113 Multiplexing separation unit 121 IPv4 / IPv6 encapsulation unit

Claims (11)

It is an in-building transmission system that transmits the broadcast signal of cable TV transmitted by optical signal as an electric signal in the building.
An optical receiver that receives an optical signal including an IP packet of a program, converts it into an electrical signal, and then encapsulates the IP packet of the program requested for viewing with a distribution IP address and outputs it.
A CMTS (Cable Modem Termination System) that transmits the encapsulated IP packet on a channel of an RF (Radio Frequency) signal that has been quadrature phase amplitude modulated based on the distribution IP address.
In common,
An in-building transmission system characterized in that each receiver receives the channel in a CM (Cable Modem), demodulates it, and then decapsulates it and returns it to the IP packet of the original program. It is an in-building transmission system that transmits the broadcast signal of cable TV transmitted by optical signal as an electric signal in the building.
An optical receiver that receives an optical signal including an IP packet of a program, converts it into an electrical signal, and then outputs an IP packet of the program requested for viewing.
An encapsulation device that encapsulates the IP packet of the program requested for viewing with the IP address for distribution, and
A CMTS (Cable Modem Termination System) that transmits the encapsulated IP packet on a channel of an RF (Radio Frequency) signal that has been quadrature phase amplitude modulated based on the distribution IP address.
In common,
An in-building transmission system characterized in that each receiver receives the channel in a CM (Cable Modem), demodulates it, and then decapsulates it and returns it to the IP packet of the original program. In the in-building transmission system according to claim 1 or 2.
The CMTS is an in-building transmission system characterized by bonding the channels and performing multicast transmission. In the in-building transmission system according to any one of claims 1 to 3.
The CMTS and the CM are transmission systems in a building, characterized in that they comply with the DOCSIS (Data Over Cable Service Interface Specifications) standard. In the in-building transmission system according to any one of claims 1 to 4.
The encapsulation is performed based on an encapsulation table in which a correspondence relationship between a program IP address and a distribution IP address is set, and the encapsulation table is updated based on a program viewing request. Transmission system. An optical receiver that receives an optical signal including an IP packet of a cable TV program and outputs the IP packet of the program requested for viewing to a CMTS (Cable Modem Termination System).
An O / E conversion unit that converts the optical signal into an electrical signal,
A transmission line coding / decoding unit that decodes the electric signal and generates an IP packet of the program.
A multiplexing separator that separates and outputs the IP packet of the program requested for viewing from the IP packet of the decoded program, and
Based on the encapsulation table in which the correspondence between the distribution IP address corresponding to the CMTS channel and the program IP address is set, the IP packet of the program output from the multiplexing / separation unit is used as the distribution IP. The encapsulation part that encapsulates with the IP header of the address,
Equipped with an optical receiver. In the optical receiving device according to claim 6,
An optical receiver, characterized in that the encapsulation table is updated based on a program viewing request. An encapsulation device that encapsulates and outputs IP packets for cable TV programs.
An encapsulation table in which the correspondence between the distribution IP address corresponding to the CMTS (Cable Modem Termination System) channel and the program IP address is set.
An encapsulation unit that encapsulates the IP packet of the input program with the IP header of the distribution IP address based on the encapsulation table.
Equipped with an encapsulation device. In the encapsulation apparatus according to claim 8,
An encapsulation device, characterized in that the encapsulation table is updated based on a program viewing request. An encapsulated decapsulation device that receives IP packets for cable TV programs.
An encapsulation table in which the correspondence between the distribution IP address and the program IP address in the CMTS (Cable Modem Termination System) is set.
A multicast protocol converter that converts a multicast join signal into a predetermined format supported by the CMTS and transmits it.
With reference to the encapsulation table, a decapsulation unit that decapsulates the IP packet of the encapsulated program,
Equipped with a deencapsulation device. In the deencapsulation apparatus according to claim 10,
A decapsulation device, characterized in that the encapsulation table is updated based on a program viewing request.

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