JP7299792B2 - transmitter and receiver - Google Patents

Description

The present invention relates to the technical fields of satellite broadcasting, terrestrial broadcasting, fixed communication and mobile communication, and more particularly to digital data transmitting and receiving devices.

In the digital transmission system, a multilevel modulation system is often used so that more information can be transmitted in the frequency bandwidth available for each service. In order to increase the frequency utilization efficiency, it is effective to increase the number of bits (modulation order) assigned to one symbol of the modulated signal. Limited by the Shannon limit. Satellite digital broadcasting is an example of a form of information transmission using a satellite broadcasting transmission path.

In satellite digital broadcasting currently in use, information correction is performed in a receiver using an error correction code. By adding a redundant signal called a parity bit to the information to be sent, it is possible to control the signal redundancy (encoding rate) and improve resistance to noise.

Error correction codes and modulation schemes are closely related, and the theoretical upper limit of frequency utilization efficiency with respect to the signal-to-noise ratio is called the Shannon limit. LDPC (Low Density Parity Check) code was proposed by Gallagher in 1962 as one of the powerful error correction codes having performance approaching the Shannon limit (see, for example, Non-Patent Document 1).

An LDPC code is a linear code defined by a very sparse parity check matrix H (parity check matrix elements consist of 0s and 1s and the number of 1s is very small).

The LDPC code is a powerful error-correcting code that can obtain transmission characteristics approaching the Shannon limit by increasing the code length and using an appropriate parity check matrix. LDPC codes are also adopted in ARIB STD-B44 (hereinafter referred to as an advanced satellite broadcasting system; see, for example, Non-Patent Document 2), which defines the transmission system of . Combining multilevel modulation with powerful error correction codes such as LDPC codes has enabled transmission with higher frequency utilization efficiency.

Taking the advanced satellite broadcasting system as an example, the code length of the LDPC code in this system is composed of Forward Error Correction (FEC) frames and is 44880 bits. It has been shown that the performance is within about 1 dB from the theoretical upper limit of the frequency utilization efficiency with respect to the signal-to-noise ratio when .

In the advanced satellite broadcasting system, the LDPC coding rate is 41/120 (≈ 1/3), 49/120 (≈ 2/5), 61/120 (≈ 1/2), 73/120 (≈ 3/5), 81/120 (≈ 2/3), 89/120 (≈ 3/4), 93/120 (≈ 7/9), 97/120 (≈ 4/5), 101/120 (≈ 5/6), 105/120 (≈7/8), and 109/120 (≈9/10).

By the way, focusing on the 12 GHz band used for satellite broadcasting, the available frequencies are tight, and there is not enough frequency bandwidth for the transmission of next-generation content that exceeds the transmission capacity of 4K/8K high-definition services. It is difficult to secure Under such circumstances, the 21 GHz band distributed to Japan as a frequency band for satellite broadcasting (BSS) by ITU-R attracts attention. Since this frequency band has a wide band of 600 MHz, AR (Augmented Reality) can be considered as a next-generation content transmission service that exceeds the transmission capacity of 4K/8K high-definition services, as well as 2K or 4K/8K Super Hi-Vision. ), VR (Virtual Reality), stereoscopic television, and other large-capacity transmission applications.

However, in digital satellite broadcasting, the transmission conditions deteriorate due to rainfall, and in digital terrestrial broadcasting, fading. In particular, in the case of transmission in the 21 GHz band, it is assumed that the effect of rainfall attenuation will be about three times as large as the dB value in the 12 GHz band.

On the other hand, recently, it has become possible to provide a service that links broadcasting and communication, such as transmitting a broadcast program from a transmitting side to a receiving device via an IP (Internet Protocol) network.

R. G. Gallager, “Low-Density Parity-Check Codes,” in Research Monograph series Cambridge, MIT Press, December 1963. "Transmission system for advanced wideband satellite digital broadcasting (ISDB-S3) standard ARIB STD-B44 Version 2.1", [online], revised on March 25, 2016, ARIB, [searched on July 2, 2001] , Internet <URL: https://www.arib.or.jp/kikaku/kikaku_hoso/std-b44.html> Suzuki et al., “Design of LDPC Code for Advanced BS Digital Broadcasting”, Journal of The Institute of Image Information and Television Engineers, Institute of Image Information and Television Engineers, Image Information Media vol.62, No.12, December 1, 2008, pp.1997 -2004

As described above, recently, in addition to the current 2K service by satellite/terrestrial broadcasting and 4K/8K Super Hi-Vision by satellite broadcasting, the provision of 4K/8K Super Hi-Vision by terrestrial broadcasting is newly expected. However, focusing on the 12 GHz band used for satellite broadcasting, available frequencies are tight, and it is difficult to secure sufficient frequency bandwidth for transmission of next-generation content beyond 4K/8K services. situation.

Therefore, another band available for satellite broadcasting is the 21 GHz band. The 21 GHz band has a bandwidth of 600 MHz allocated for satellite broadcasting, and is a promising transmission band for realizing large-capacity transmission.

However, compared to the 12 GHz band, the 21 GHz band is more affected by rain attenuation. , the modulation order must be lowered below the maximum modulation order (32APSK) specified in the advanced wideband digital satellite broadcasting transmission system (ISDB-S3).

In addition, recently, with the convergence of broadcasting and communication, the diversification of transmission forms beyond the boundaries of radio waves is progressing, and in particular, the sharing of IP-based transmission means is progressing. Next-generation communication networks such as 5G are also being considered for integration with satellite broadcasting transmission lines, and it is expected that the sharing of IP-based transmission means will further accelerate in the future.

For this reason, a transmission system for 21GHz-band satellite broadcasting that takes into account the convergence of broadcasting and communications is required. There is a demand for a transmission means that has a high affinity with IP while improving transmission performance by adopting a coded modulation system that considers the influence and enabling commonality with the signal form of IP-based transmission means.

Therefore, in view of the above-mentioned problems, an object of the present invention is to provide a transmission device that enables transmission with high compatibility with IP while improving transmission performance as a transmission system for 21 GHz band satellite broadcasting that takes into account the convergence of broadcasting and communication. and to provide a receiver.

A transmission device according to the present invention is a transmission device for transmitting IP-based program data as a modulated wave signal through a 21 GHz band satellite broadcasting transmission path, wherein the IP-based program data is stored in variable-length IP packets. A signal is input, the data area of the IP signal is extracted, and an identification signal of a fixed pattern indicating that the IP-based program data is stored and an additional header describing data length information are added to the IP packet. 188 bytes of 188 bytes by inserting and concatenating in packet length units and dividing in 187 byte units while adding 1 byte MPEG-2 TS TS synchronization signals so as to form fixed length TS packet strings of MPEG-2 TS. IP-TS converting means for converting a signal into a TS packet sequence of MPEG-2 TS in TS packet units; transmission line coding means for deleting and concatenating signals to generate a modulation symbol frame subjected to predetermined coding modulation processing; and orthogonal modulation corresponding to a modulation scheme in the modulation symbol frame obtained from the transmission line coding means and quadrature modulation means for performing processing and waveform shaping to generate a modulated wave signal.

Further, in the transmitting apparatus of the present invention, the transmission line coding means uses, as the predetermined coding modulation processing, the inner code based on the transmission system of advanced wideband satellite digital broadcasting as an LDPC code and the outer code as a BCH code. means for performing error correction coding processing on a main signal composed of an integer multiple of 187 bytes with the code length of the LDPC code set to 44880 bits regardless of the LDPC coding rate by the concatenated code, As the LDPC coding rate, all LDPC coding rates used in the transmission system of advanced wideband satellite digital broadcasting can be used, and the modulation symbol frame is generated by a modulation system with a modulation order of 8PSK or less. do.

Further, in the transmitting apparatus of the present invention, the IP-TS conversion means configures the additional header with 10 bytes, describes the identification signal in the leading 8 bytes of the additional header, and stores the packet length of the IP packet as data. The length is described in the lower 2 bytes in the additional header.

Further, a receiving apparatus of the present invention is a receiving apparatus for receiving a modulated wave signal transmitted from the transmitting apparatus of the present invention, and after applying waveform shaping and adaptive equalization processing to the received modulated wave signal, Orthogonal demodulation means for performing orthogonal demodulation processing and forming a transmission frame used for error correction decoding processing, and error correction decoding processing for the transmission frame obtained from the orthogonal demodulation means, and main signal data after error correction decoding. Transmission channel decoding means for generating a TS packet string of MPEG-2 TS in 188-byte TS packet units in which a 1-byte MPEG-2 TS TS synchronization signal is added to 187 bytes, and obtained from the transmission channel decoding means Remove the TS synchronization signal from each TS packet of MPEG-2 TS, concatenate the data of the main signal of the TS packet string, and refer to the additional header for the concatenated data string to determine the packet length unit of the IP packet. TS-IP conversion means for extracting the IP packet transmitted from the transmitting device by performing signal division and then removing the additional header, and generating an IP signal using the extracted IP packet. characterized by

According to the present invention, it is possible to construct a transmission system for 21 GHz band satellite broadcasting that considers the fusion of broadcasting and communication, and enables transmission that is highly compatible with IP while improving transmission performance.

1 is a block diagram showing a schematic configuration of a transmission system including a transmitting device and a receiving device according to one embodiment of the present invention; FIG. 1 is a block diagram showing a schematic configuration of a transmitter of one embodiment according to the present invention; FIG. FIG. 4 is a diagram showing signal conversion processing of an IP-TS converter in the transmission device of one embodiment according to the present invention; 4(a) and 4(b) are diagrams respectively showing a transmission frame configured by a channel coding section in the transmission apparatus of the embodiment according to the present invention and transmission frame configuration bits for each LDPC coding rate; FIG. FIG. 4 is a diagram showing a modulation symbol frame configured by a transmission line coding section in the transmitting apparatus of one embodiment according to the present invention; 1 is a block diagram showing a schematic configuration of a receiving device of one embodiment according to the present invention; FIG. FIG. 4 is a diagram showing signal conversion processing of the TS-IP converter in the receiving device of one embodiment according to the present invention;

(transmission system)
First, a configuration example of a transmission system 1 including a transmitting device 2 and a receiving device 5 according to one embodiment of the present invention will be described.

FIG. 1 is a block diagram showing a schematic configuration of a transmission system 1 including a transmitter 2 and a receiver 5 according to one embodiment of the present invention. In the transmission system 1 shown in FIG. 1, the signal source device 3 stores IP-based program data and outputs an IP signal of certain program data to the transmission device 2 via the IP network 6 . The transmission device 2 inputs the IP signal of the program data from the signal source device 3 via the IP network 6 in consideration of the fusion of broadcasting and communication, and converts the IP signal of the program data into an identifiable MPEG-2. 2 Generate TS. Then, from this MPEG-2 TS, the transmission device 2 generates a modulated wave signal based on the advanced wideband satellite digital broadcasting transmission system (ISDB-S3), which takes into consideration the effects of rain attenuation, and The signal is transmitted to the receiving device 5 through the transmission antenna 2a and the satellite broadcasting transmission line of the broadcasting satellite 4 for 21 GHz band satellite broadcasting. On the other hand, the receiving device 5 receives the modulated wave signal through the receiving antenna 5a, demodulates and decodes it, restores the MPEG-2 TS, extracts the IP signal, and outputs it to the outside.

Although it is not directly related to the gist of the present invention, in consideration of the integration of broadcasting and communication, both the transmitting device 2 and the receiving device 5 have a transmission mode in addition to the transmission mode shown in FIG. The device 2 and the receiving device 5 may be connected by an IP network and have a function of two-way communication of IP signals. For example, in addition to the transmission mode shown in FIG. 1, the transmitting device 2 has a function of transmitting the IP signal of the program data input from the signal source device 3 via the IP network 6 to the receiving device 5 via the IP network. and the receiving device 5 may have a function of receiving the IP signal via the IP network.

Hereinafter, specific configurations and operations of the transmitting device 2 and the receiving device 5 will be described in order with reference to the drawings.

(Transmitter)
FIG. 2 is a block diagram showing a schematic configuration of the transmitter 2 of one embodiment according to the present invention. The transmission device 2 receives an IP signal of program data as an input source, and includes an IP-TS converter 21 , a channel encoder 22 , and an orthogonal modulator 23 .

The IP-TS conversion unit 21 receives an IP signal in which IP-based program data is stored in variable-length IP packets from the signal source device 3 via the IP network 6, extracts the data area of the IP signal, An identification signal of a fixed pattern indicating that IP-based program data is stored and an additional header describing data length information are inserted and concatenated in units of the packet length of the IP packet, and the fixed length of MPEG-2 TS is generated. (188 bytes) TS packet string of MPEG-2 TS is divided into 187-byte units while adding a 1-byte MPEG-2 TS TS sync signal to form a TS packet string of 188 bytes. , and output to the transmission line coding unit 22 .

FIG. 3 shows a processing method for signal conversion from an IP signal to a TS packet sequence of MPEG-2 TS as signal conversion processing in the IP-TS conversion unit 21 . As shown in FIG. 3, the IP-TS conversion unit 21 extracts only the data area of the input IP signal (upper part of the figure) and inserts an additional header (middle part of the figure) as procedure 1. ), and as procedure 2, a TS synchronization signal (1 byte; 0x47) of MPEG-2 TS is added, and TS packetization of fixed-length MPEG-2 TS of 188 bytes is performed (lower stage in the figure).

First, an IP signal input to the IP-TS conversion unit 21 is mainly composed of a preamble, an Ethernet (registered trademark) frame header (hereinafter also referred to as "E frame header"), data, and FCS (Frame Check Sequence). be done. The preamble, E-frame header, and FCS are used for communication processing in the transmitting device 2 for receiving IP signals from the signal source device 3 via the IP network 6 . Program data such as video to be sent via the satellite broadcasting transmission path is contained in IP packets configured as variable-length "data" shown in FIG. )include.

Therefore, in procedure 1, the additional header is composed of 10 bytes, and the IP-TS converter 21 inserts a fixed pattern identification signal indicating that IP-based program data is stored in the leading 8 bytes of the additional header. is described, the packet length of the IP packet is determined as the data length, and the data length is described as data length information (16 bits) in the lower 2 bytes of the additional header. That is, the 9th byte of the additional header describes the upper 8 bits of the data length information, and the 10th byte describes the lower 8 bits of the data length information. This identification signal is a fixed pattern unique to the selected channel (broadcast channel of 21 GHz band) in the receiver 5 and is known between the transmitter 2 and the receiver 5 .

For example, the additional header in this example is:
1st byte: 0x55,
2nd byte: 0xC4,
3rd byte: 0x50,
4th byte: 0xF4,
5th byte: 0x6F,
6th byte: 0xD3,
7th byte: 0x44,
8th byte: 0xC9,
9th byte: data length information (upper 8 bits), and
10th byte: data length information (lower 8 bits),
consists of

By defining the 10-byte additional header as described above, the receiving device 5 can identify that the IP-based program data is stored for each selected channel (broadcast channel in the 21 GHz band), and On the transmission device 2 side, it is possible to perform efficient TS packetization while determining the data length of the IP signal (variable length IP packet) of the program data to be transmitted, thereby improving the transmission efficiency. Since the additional header has a fixed pattern in the leading 8 bytes, even if the additional header is divided, the TS packet string can be easily concatenated on the receiving device 5 side, and the IP-based program data can be identified. becomes. As described above, in procedure 1, efficient segmentation is realized by inserting an additional header containing data length information of a variable-length packet for each packet length of the IP packet.

Subsequently, in procedure 2, the IP-TS conversion unit 21 adds a TS synchronization signal (1 byte) of MPEG-2 TS to the various information (additional header and data) obtained in procedure 1. constitutes the same signal format as MPEG-2 TS.

As shown in FIG. 3, in Procedure 2, as a case of MPEG-2 TS TS synchronization signal addition,
・TS synchronization signal 1 byte + additional header 10 bytes + data 177 bytes (Case 1),
・TS synchronization signal 1 byte + data 187 bytes (Case 2),
・TS synchronization signal 1 byte + data 177 bytes + additional header 10 bytes (Case 3),
An example is shown. In addition to the above case, there may be cases where the additional header is divided into a plurality of pieces, but since the additional header has a fixed pattern in the leading 8 bytes, it can be easily concatenated on the receiving device 5 side.

By having this format, for example, an existing interface circuit for MPEG-2-TS using a TS synchronization signal can be used between the IP-TS converter 21 and the channel encoder 22 in FIG. It becomes possible.

The channel coding unit 22 removes the 1-byte TS synchronization signal from the beginning of the 188-byte MPEG-2 TS TS packet string obtained from the IP-TS conversion unit 21 to improve information efficiency. Concatenate and store the information of the concatenated TS packet string in bit string units according to the LDPC coding rate of the error correction coding process in a transmission frame based on the advanced wideband satellite digital broadcasting transmission system (ISDB-S3), Transmission frame information is generated by performing error correction coding processing (BCH code and LDPC code) on the bit string, and a modulation symbol frame is generated by further performing modulation symbol mapping processing, and is output to the orthogonal modulation section 23 .

FIGS. 4(a) and 4(b) are diagrams respectively showing a transmission frame configured by the transmission line encoder 22 in the transmission device 2 of the embodiment according to the present invention and transmission frame configuration bits for each LDPC coding rate. . As shown in FIG. 4( a ), the transmission line coding unit 22 performs error correction coding processing such that the inner code is an LDPC code and the outer code is is the concatenated code configuration of the BCH code, and the code length of the LDPC code is 44880 bits.

That is, the transmission line coding unit 22 uses a BCH code generator polynomial similar to the transmission system of advanced wideband satellite digital broadcasting (ISDB-S3) to generate the BCH code of the outer code for the frame header and the bit string of the main signal. It is possible to correct any 12 bits in one transmission frame because of the conversion processing. Then, the transmission path coding unit 22 flattens the modulation spectrum by performing 17th-order energy spreading on the BCH-encoded bit string (frame header, main signal, BCH code parity, stuff bits). LDPC code parity is added by LDPC encoding processing according to the encoding rate to form one transmission frame. In addition, in the advanced wideband digital satellite broadcasting transmission system (ISDB-S3), it is stipulated that the 25th order energy diffusion processing is performed on the bit string (frame header, main signal, BCH code parity, stuff bit) after BCH encoding. However, in this embodiment, as will be described later, the modulation order of 8PSK or less is used, so that the 17th-order energy diffusion processing is sufficiently flattened to reduce the processing load.

Therefore, as shown in FIG. 4(a), a transmission frame consists of a frame header (176 bits), main signal, BCH code parity (192 bits), stuff bits (6 bits), and LDPC code parity. Then, as shown in FIG. 4(b), the transmission line coding unit 22 makes it possible to use all LDPC coding rates that can be used in the advanced wideband satellite digital broadcasting transmission system (ISDB-S3), and one transmission The frame code length is always 44880 bits. By selecting and setting the LDPC coding rate (external instruction), the strength of the error correction code can be changed according to circumstances, and the transmission quality between the transmitting device 2 and the receiving device 5 can be easily maintained. The LDPC coding rate and modulation scheme setting information are described in a TMCC signal (transmission control signal) that is time-division multiplexed and transmitted in a modulation symbol frame related to transmission of the main signal. It should be noted that the TMCC signal (transmission control signal) can be multiplexed with a signal subjected to 11th-order energy diffusion processing, which will be described later, and transmitted by .pi./2 shift BPSK.

Also, as shown in FIG. 4(b), the main signal in the transmission frame is in units of bit strings corresponding to the LDPC coding rate of the LDPC code, and all consist of integral multiples of 187 bytes. For this reason, the transmission path coding unit 22 can configure a transmission frame that is consistent with the IP-TS conversion unit 21 and has no excess or deficiency.

Subsequently, the transmission path coding unit 22 generates a modulation symbol frame by applying modulation symbol mapping processing to the information of the transmission frame subjected to the error correction coding processing. Here, in the transmission device 2 according to the present invention, the modulation method used for constructing the modulation symbol frame in the transmission path coding unit 22 is the maximum modulation specified in the transmission method for advanced wideband satellite digital broadcasting (ISDB-S3). A modulation system with a modulation order of 8PSK or less, which is lower than the modulation order (32APSK), is used, and more specifically, there are two types, QPSK and 8PSK. As a result, even when the influence of rain attenuation is large for 21 GHz band satellite broadcasting, a sufficient required C/N margin can be ensured in combination with the error correction coding processing using the LDPC code and BCH code.

FIG. 5 is a diagram showing a modulation symbol frame formed by the transmission line coding section 22 in the transmission device 2 of one embodiment according to the present invention. The modulation symbol frame shown in FIG. 5 is composed of π/2 shift BPSK with a unique word (18D2E82 (hexadecimal notation)) as the leading 26 symbols, followed by 187 symbols of main signal modulation symbols, and 4 symbols of phase reference. BPSK is repeated 120 times for QPSK and 80 times for 8PSK to modulate the information of the transmission frame shown in FIG. 4(a). Also, an eleventh-order energy spreading circuit is applied as an input source of π/2 shift BPSK for phase reference. In addition, in the advanced wideband satellite digital broadcasting transmission system (ISDB-S3), it is specified that 15th order energy diffusion processing is performed as an input source of π/2 shift BPSK for phase reference, but in this embodiment, Since it is used as a phase reference for a modulation system with a modulation order of 8PSK or less, it is sufficiently flattened by the 11th-order energy diffusion processing, thereby reducing the processing load.

In this way, the modulation symbol frame configured by the transmission line coding unit 22 has two types of modulation schemes, QPSK and 8PSK, and the transmission frame and the modulation symbol frame are determined by which of the main signal modulation schemes is QPSK or 8PSK. However, it is possible to maintain a one-to-one relationship. When the modulation method of the main signal is 8PSK, the transmission path coding unit 22 performs orthogonal modulation in the same manner as the transmission method of advanced wideband digital satellite broadcasting (ISDB-S3) for the purpose of improving the decoding performance of the LDPC code. Just before modulation symbol mapping by section 23 , bit interleaving is applied only to the main signal and output to quadrature modulation section 23 .

The quadrature modulation section 23 performs quadrature modulation processing corresponding to the modulation scheme in the modulation symbol frame obtained from the channel coding section 22, performs waveform shaping by a roll-off filter, and generates and outputs a modulated wave signal.

(receiving device)
FIG. 6 is a block diagram showing a schematic configuration of the receiver 5 of one embodiment according to the present invention. The receiving device 5 receives as an input source a modulated wave signal obtained from the receiving antenna 5a in FIG.

The quadrature demodulator 51 subjects the received modulated wave signal to waveform shaping by the same roll-off filter as that of the transmission device 2, and adaptive equalization processing for correcting waveform distortion occurring in the satellite broadcasting transmission path. After that, based on the TMCC signal (transmission control signal) that has been demodulated and decoded in advance, orthogonal demodulation processing is performed using the same modulation method as that of the transmission device 2, and demapping is performed on the signal after orthogonal demodulation. A transmission frame shown in FIG.

In the process of the orthogonal demodulation process, the orthogonal demodulation section 51 performs phase synchronization using π/2 shift BPSK for the phase reference after the energy despreading process and detection of the unique word composed of 26 symbols shown in FIG. By doing so, the main signal in FIG. 5 can be obtained. In the case of QPSK, the main signal 187 symbols concatenated from the unique word are concatenated 120 times, and in the case of 8PSK, the main signal 187 symbols are concatenated 80 times, and demapping is performed to obtain one transmission frame of 44880 bits shown in FIG. can be reconstructed. Further, in the case of 8PSK, since bit interleaving is performed in the transmitting device 2, the corresponding deinterleaving is also performed in the receiving device 5 to maintain bit consistency. In the demapping, for the LDPC decoding processing in the transmission path decoding unit 52, the likelihood determination processing is normally performed to increase the probability value based on the likelihood indicating the likelihood that the information bit is 0 or 1, and then transmitted. Since the frame is reconstructed, it is desirable that the likelihood determination process should correspond to the C/N of the received signal.

Subsequently, the transmission path decoding unit 52 performs error correction decoding processing (LDPC decoding, energy despreading and BCH decoding) corresponding to the error correction encoding processing by the transmission device 2 for the transmission frame obtained from the orthogonal demodulation unit 51. to generate a TS packet string of MPEG-2 TS in units of 188-byte TS packets in which a 1-byte TS synchronization signal of MPEG-2 TS is added to 187 bytes of data of the main signal after error correction decoding, and TS - output to the IP conversion unit 53;

On the receiving device 5 side as well, an existing interface circuit for MPEG-2-TS using the TS synchronization signal is used between the transmission path decoder 52 and the TS-IP converter 53 .

The TS-IP conversion unit 53 deletes the leading 1-byte TS synchronization signal from each TS packet of the MPEG-2 TS obtained from the transmission line decoding unit 52, concatenates the data of the main signal of the TS packet sequence, and concatenates the concatenation With respect to the subsequent data string, the additional header is referred to, and the signal is divided by the packet length unit of the IP packet, and then the additional header is removed, thereby extracting the IP packet transmitted from the transmitting device 2. A preamble, an E frame header, and an FCS are added to each IP packet for local area network transmission, and an IP signal is generated using the extracted IP packet and output to the outside.

FIG. 7 shows a processing method for signal conversion from a TS packet sequence of MPEG-2 TS to an IP signal as signal conversion processing in the TS-IP conversion unit 53 . As shown in FIG. 7, the TS-IP conversion unit 53 deletes the TS synchronization signal at the beginning of the input TS packet string of MPEG-2 TS (upper part of the figure) and concatenates the TS packet string. After this TS concatenation, the additional header is referred to and the signal is divided, and then the additional header is removed (the middle part of the figure). As described above, since the data length information is described in the 9th and 10th bytes of the additional header, it is possible to perform signal division by referring to the additional header based on this information. Subsequently, the TS-IP converter 53 extracts the IP packet, adds a preamble, an E-frame header, and an FCS for local area network transmission if necessary, and generates an IP signal (lower part in the figure).

By the above processing, the receiving device 5 can efficiently acquire the variable-length IP signal transmitted from the transmitting device 2 via the satellite broadcasting transmission line.

Therefore, the transmitting device 2 and the receiving device 5 according to the present invention can perform transmission with high compatibility with IP while improving transmission performance as a transmission system of 21 GHz band satellite broadcasting considering the convergence of broadcasting and communication.

With respect to the above-described embodiment, a program for configuring a computer functioning as each of the transmitting device 2 and the receiving device 5 and causing each means of the transmitting device 2 and the receiving device 5 to function can be preferably used. Specifically, a control unit for controlling each means can be configured by a central processing unit (CPU) in a computer, and at least a storage unit for appropriately storing programs required to operate each means It can be configured with one memory. That is, by causing the CPU of such a computer to execute the program, the functions of the above-described means can be realized. Further, a program for realizing the function of each means can be stored in a predetermined area of the aforementioned storage section (memory). Such a storage unit can be configured with a RAM or ROM inside the device, or can be configured with an external storage device (eg, hard disk). Also, such a program can be made up of a part of software (stored in a ROM or an external storage device) on an OS used in a computer. Furthermore, a program for causing such a computer to function as each means can be recorded on a computer-readable recording medium. Moreover, each of the means described above can be configured as a part of hardware or software, and can be realized by combining them.

Although the above embodiments have been described as representative examples, it will be apparent to those skilled in the art that many modifications and substitutions may be made within the spirit and scope of the invention. Accordingly, the present invention should not be construed as limited by the above-described embodiments, but only by the appended claims.

The transmitting device and the receiving device according to the present invention have a strong error correction function against rain attenuation that may occur in the 21 GHz band, and have IP signal conversion processing based on the additional header. Since it is possible to improve compatibility with IP signals while maintaining inter-phase synchronization, it is useful for applications of 21 GHz band satellite broadcasting.

1 transmission system 2 transmitter 2a transmitter antenna 3 signal source device 4 broadcasting satellite 5 receiver 5a receiver antenna 6 IP network 21 IP-TS converter 22 channel encoder 23 quadrature modulator 51 quadrature demodulator 52 channel decoder 53 TS-IP converter

Claims (4)

A transmission device for transmitting IP-based program data as a modulated wave signal via a 21 GHz band satellite broadcasting transmission line,
Inputting an IP signal in which the IP-based program data is stored in a variable-length IP packet, extracting a data area of the IP signal, and identifying a fixed pattern indicating that the IP-based program data is stored. TS synchronization of 1-byte MPEG-2 TS is performed so as to form fixed-length TS packet strings of MPEG-2 TS by inserting additional headers describing signal and data length information in packet length units of the relevant IP packets and concatenating them. IP-TS conversion means for converting signals into TS packet trains of MPEG-2 TS in units of 188-byte TS packets by dividing into 187-byte units while adding signals;
Transmission of deleting the TS synchronization signal from the 188-byte unit MPEG-2 TS packet sequence obtained from the IP-TS conversion unit, concatenating it, and generating a modulation symbol frame subjected to a predetermined coding modulation process. a road encoding means;
Quadrature modulation means for performing quadrature modulation processing corresponding to the modulation scheme in the modulation symbol frame obtained from the transmission line coding means and performing waveform shaping to generate a modulated wave signal;
A transmitting device comprising: The transmission line coding means, as the predetermined coding modulation processing, converts the LDPC code into a concatenated code in which the inner code is an LDPC code and the outer code is a BCH code based on the transmission system of advanced wideband satellite digital broadcasting. It has means for performing error correction coding processing for encoding a main signal composed of an integer multiple of 187 bytes with a code length of 44880 bits regardless of the LDPC coding rate, and the LDPC coding rate is an advanced wideband The transmission according to claim 1, characterized in that all LDPC coding rates used in the transmission system of satellite digital broadcasting can be used, and the modulation symbol frame is generated by a modulation system with a modulation order of 8PSK or less. Device. The IP-TS conversion means configures the additional header with 10 bytes, describes the identification signal in the leading 8 bytes of the additional header, and sets the packet length of the IP packet as the data length to the lower 2 bytes of the additional header. 3. A transmitting device according to claim 1 or 2, characterized in that: A receiving device for receiving a modulated wave signal transmitted from the transmitting device according to any one of claims 1 to 3,
quadrature demodulation means for performing waveform shaping and adaptive equalization processing on the received modulated wave signal and then performing quadrature demodulation processing to form a transmission frame used for error correction decoding processing;
Error correction decoding processing is performed on the transmission frame obtained from the orthogonal demodulation means, and a 188-byte TS packet obtained by adding a 1-byte MPEG-2 TS TS synchronization signal to the 187-byte data of the main signal after error correction decoding. Transmission path decoding means for generating a TS packet sequence of MPEG-2 TS as a unit;
The TS synchronization signal is deleted from each TS packet of MPEG-2 TS obtained from the transmission line decoding means, the data of the main signal of the TS packet string is concatenated, and the additional header is referred to for the concatenated data string. The TS- extracts the IP packet transmitted from the transmitting device by dividing the IP packet by packet length unit and then removing the additional header, and generates an IP signal using the extracted IP packet. IP conversion means;
A receiving device comprising:

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