JP2002051017A - Re-transmitter for transport stream, and receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a re-transmitter that gives no adverse effect on a lower layer service side even when an error rate at a high layer service side receiving hierarchically transmitted packets gets higher in a system such as a cable television system. SOLUTION: The re-transmitter 4 receives a transport stream of a BS digital broadcast or the like, adds error information or the like for each layer to the received transport stream, retransmits high layer packets and low layer packets to each receiver 3 without distinguishing the modulation system for the packets, each receiver 3 receives the high layer packets and the low layer packets, converts the high layer packets having errors into null packets, decodes the high layer packets and the low layer packets while the high layer packets including errors give no adverse effect on the low layer packets and allows a viewer to view programs provided by high layer or low layer services.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a modulation system which is different for each layer by a retransmitting device such as a cable television system which receives a BS digital broadcast and retransmits it to a receiving device in each home. Receiving one transport stream in which the high-layer packet and the low-layer packet modulated by the above are layer-transmitted, and modulating the high-layer packet constituting the transport stream;
The present invention relates to a retransmitting device of a transport stream retransmission / reception system for retransmitting to a receiving device without distinguishing from a modulation method of a lower layer packet, and a receiving device.

[Summary of the Invention] [0002] The present invention relates to a modulation scheme that is different for each layer by a retransmitting device such as a cable television system that receives a BS digital broadcast and retransmits it to a receiving device in each home. One transport stream in which the modulation scheme of the high-layer packet and the low-layer packet modulated by the multiplexing method is transmitted hierarchically is received, and the modulation scheme of the high-layer packet and the modulation scheme of the low-layer packet forming the transport stream are received. In the retransmission device of the transport stream retransmission / reception system for retransmitting to each receiving device without distinguishing from the modulation method, and in the receiving device, the level of the hierarchy, the error, To generate information indicating the presence or absence of, and to receive and reproduce this information on the receiving device side,
In addition to determining whether or not there is an error in the layer-transmitted packets for each layer, and determining the error rate, when the lower layer is selected, the higher layer packet is invalidated so that an arbitrary layer service can be selected. Even if the high-layer packet contains many errors, the low-layer service is not adversely affected.

[0003]

2. Description of the Related Art A BS digital broadcast (Ministry of Posts and Telecommunications Ordinance Heisei 1) defined as one of systems for performing a hierarchical transmission service.
No. 102 of the 1st year), in order to secure a higher service time rate, a transmission system that requires a high C / N but enables large-capacity transmission, and a transmission system that has a small transmission capacity but can receive even a low C / N. A method using the transmission method together is adopted (ARIB STD-B20).

[0004] By providing the hierarchical transmission service, even if the high-layer service is interrupted due to a large rainfall attenuation, a low-layer service transmitted by a transmission method that can be received even in a low C / N is presented. Can be.

[0005] When a hierarchical transmission service is received, a PID (Packet Identifier) of a transport stream packet (a transport stream packet defined by ISO / IEC 13818-1) is received on the receiving device side. By specifying, it is possible to select either the high-layer service or the low-layer service.

[0006] However, if the PID of the high-layer service is erroneously matched with the PID of the low-layer service when the low-layer service is selected, the low-layer service is obstructed and the low-layer service is hardly received. turn into.

Therefore, in a receiving apparatus for directly receiving a wireless hierarchical transmission service, when a low hierarchical service is selected, the transport stream packet of the high hierarchical service is invalidated so that the low hierarchical service is not disturbed. Measures have been proposed (Japanese Patent No. 29
12323).

[0008] In a receiving apparatus compatible with BS digital broadcasting, a transmission multiplexing configuration (TMCC) is used.
uration control) signal, it is possible to identify the modulation scheme of each packet in a frame in which a plurality of transport streams are multiplexed, to receive a high-layer packet and a low-layer packet separately, and to receive the signal. The side can automatically select and switch between layers by estimating the error rate of the higher layer service using information such as the reception C / N.

[0009]

By the way, in a cable television system or the like, a transport stream provided with a hierarchical transmission service, for example, a BS digital broadcast transport stream is received, and a higher-layer packet of this transport stream is received. Retransmission is performed to each receiving apparatus without distinguishing between the modulation schemes of the packet and the lower layer packet.

[0010] In such a system, since an index for switching between the high-layer service and the low-layer service is not transmitted to each receiving device, there is a problem that the high-layer service and the low-layer service cannot be switched. there were.

In such a system, when the receiving apparatus receives a low-layer service, the transport stream packet of the high-layer service is erroneously recognized as a packet of the low-layer service, and the low-layer service is not transmitted. May be obstructed. However, there is a problem that a method for preventing such low-layer services from interfering has not been established.

[0012] In order to cope with such a problem, a method has been proposed in which, when an error contained in a high-layer packet cannot be corrected, the high-layer packet is invalidated on the retransmitting device side and retransmitted to each receiving device. Have been.

However, according to such a method, each receiving apparatus cannot receive both the high-layer packet and the low-layer packet, and cannot select the high-layer service and the low-layer service. However, when the high-layer packet is degraded and the high-layer packet is discarded on the retransmitting device side, the error concealment (Erro
r Concealmant) to eliminate the possibility of devising signal processing, such as raising the time rate of high-layer services.

In view of the above circumstances, the present invention allows a transport stream in which a hierarchical transmission service is performed to be received, and without discriminating between a modulation scheme of a high-layer packet and a modulation scheme of a low-layer packet, each reception stream is transmitted. An object of the present invention is to provide a transport stream retransmitting apparatus that can prevent a lower layer service side from being adversely affected even when an error rate of a higher layer service side becomes high when the apparatus side retransmits. And

[0015] In addition, a retransmission apparatus that receives a transport stream in which a hierarchical transmission service is performed retransmits a modulation scheme of a high-layer packet and a modulation scheme of a low-layer packet without distinction. It is an object of the present invention to provide a transport stream receiving apparatus capable of receiving a low-layer service without being affected by an error rate of a high-layer service when the error rate is high.

[0016]

In order to achieve the above object, according to the present invention, after receiving a transport stream in which a hierarchical transmission service is provided, the present invention relates to a high-speed transport stream included in the transport stream. In a transport stream retransmitting device that retransmits to each receiving device without distinguishing the modulation scheme between a hierarchical packet and a lower hierarchical packet, when retransmitting a transport stream, each packet constituting the transport stream is There is provided a means for generating information indicating whether the packet is a high-layer packet or a low-layer packet, and transmitting the generated information to each receiving device.

According to the present invention, after receiving a transport stream in which a hierarchical transmission service is performed, each received stream is distinguished without discriminating a modulation scheme between a high-layer packet and a low-layer packet included in the transport stream. In a transport stream retransmitting device for retransmission to a device, when retransmitting a transport stream, error information indicating presence or absence of an error is generated for each packet constituting the transport stream and transmitted to each receiving device. It is characterized by having means for performing.

According to the third aspect of the present invention, the modulation scheme of the high-layer packet and the low-layer packet included in the transport stream is not distinguished from the retransmitting device receiving the transport stream in which the layer transmission service is provided. Receiving a retransmitted transmission signal, a receiving device that decodes a high-layer packet or a low-layer packet, when a low-layer service is selected, based on the layer information transmitted from the retransmission device, There is provided a means for invalidating a high-layer packet of a transport stream obtained by receiving a transmission signal and decoding a low-layer packet.

According to a fourth aspect of the present invention, the modulation scheme of the high-layer packet and the low-layer packet included in the transport stream is not distinguished from the retransmitting device receiving the transport stream in which the layer transmission service is provided. A receiving device that receives the retransmitted transmission signal and decodes the high-layer packet or the low-layer packet, based on the error information for each packet transmitted from the retransmission device, It is characterized by comprising means for calculating and selecting a layer and decoding a high-layer packet or a low-layer packet.

In the above configuration, according to the first aspect, when retransmitting the transport stream, each packet constituting the transport stream is a higher layer packet,
By generating information indicating which of the low-layer packets is to be transmitted to each receiving device, even if the error rate on the high-layer service side increases, the low-layer service side on the receiving device side is adversely affected. Do not give.

According to the present invention, when the transport stream is retransmitted, error information indicating the presence or absence of an error is generated for each packet constituting the transport stream and transmitted to each receiving apparatus. Each receiving apparatus is made to calculate the error rate of the high-layer packet and the low-layer packet so that the optimum layer service can be selected, and even if the error rate of the high-layer service increases, the low-layer service Avoid adverse effects on the side.

According to the third aspect, when the low-layer service is selected, the high-layer packet of the transport stream obtained by receiving the transmission signal is invalidated based on the layer information transmitted from the retransmission device. By decoding the low-layer packet, even if the error rate on the high-layer service side becomes high, the low-layer service can be received without being affected by the error rate.

According to a fourth aspect of the present invention, the error rate of each packet is calculated based on the error information of each packet transmitted from the retransmitting device, and the layer is selected automatically or manually, and the higher layer packet or the lower layer is selected. By decoding the hierarchical packet, the error rate of the high-layer packet and the low-layer packet is calculated, so that the optimum hierarchical service can be selected. To receive low-tier services without being affected by

[0024]

FIG. 1 is a block diagram showing an embodiment of a transport stream retransmission apparatus according to the present invention. FIG. 2 is a block diagram showing an embodiment of a transport stream retransmission / reception system using a transport stream retransmission device and a reception device according to the present invention. In the following description, as an example,
With the retransmission device of the cable television system,
Receives a transport stream signal of BS digital broadcasting in which hierarchical transmission is performed, and without discriminating between a high-layer packet, a low-layer packet modulation method, and a low-layer packet modulation method, It is assumed that a low-layer packet is transmitted over a cable, and each of the receiving devices connected to the cable selects either the high-layer service or the low-layer service for viewing.

First, the transport stream retransmission / reception system shown in FIG. 1 will be described. The transport stream retransmission / reception system 1 receives a high-layer packet, a low-layer packet, and the like that constitute a transport stream via a cable 2 and receives a plurality of receiving devices 3 that receive a high-layer service or a low-layer service.
And a transport stream in which a hierarchical transmission service is performed, for example, a transport stream of a BS digital broadcast is received, and without discriminating between the modulation schemes of the high-layer packets and the low-layer packets constituting the transport stream, And a retransmitting device 4 which sends out the data on the cable 2 with layer error information and the like to be received by each receiving device 3.
A digital broadcast transport stream is received, and error information of each layer is added thereto without discrimination between modulation schemes of high-layer packets and low-layer packets constituting the transport stream, and transmitted on the cable 2. Then, each receiving device 3 receives the high-layer packet, the low-layer packet, the error information of each layer, and the like transmitted on the cable 2, and allows the user to view the program provided by the high-layer service or the low-layer service.

As shown in FIG. 1, the retransmitting device 4 performs a receiving process of receiving a modulated wave of a signal (a signal such as a BS digital broadcast) for which a hierarchical transmission service is performed, and a receiving process obtained by the receiving process. A demodulation process of demodulating the signal and reproducing a transport stream before performing error correction by the Reed-Solomon code, and in parallel with the demodulation process, a transmission multiplexing conflict (TMCC) included in the received signal.
Hierarchical transmission that processes signals and extracts information (hierarchical information) indicating whether each packet of the transport stream included in the frame belongs to a higher-layer packet or a lower-layer packet. A decoding process for decoding the Reed-Solomon code of the transport stream output from the reception demodulation unit 5 and the hierarchical transmission reception demodulation unit 5 is included in the transport stream using the Reed-Solomon code obtained in the decoding process. Error correction processing to correct the error of the high-layer packet and the low-layer packet to be corrected, and when there is a high-layer packet and a low-layer packet for which the error cannot be corrected by this error correction processing, the high-layer packet and the low-layer packet for which the error could not be corrected Reed-Solomon decoding unit that performs error information generation processing for generating information (error information) It is equipped with a door.

Further, the retransmitting device 4 outputs the transport stream output from the Reed-Solomon decoding unit 6 after error correction using the Reed-Solomon code, error information, and the hierarchical transmission reception demodulation unit 6. For example, as shown in FIG. 3, transmission information in a format suitable for cable television, such as hierarchical information for each packet, is contained in a frame header provided for a first slot to an M-th slot constituting a frame. TS placement information (transport stream placement information) is placed after the synchronization word, and after this TS placement information, layer information indicating whether each packet belongs to a higher layer packet or a lower layer packet, and each packet has an error. Transmission line encoding section 7 for generating a transmission signal in which error information indicating whether or not the transmission path code is included, and the transmission path code Modulates the transmission signal output from the unit 7, and sent onto the cable 2, and a modulation unit 8 for receiving the respective receiving devices 3.

Then, while receiving and demodulating the modulated wave of the BS digital broadcast and reproducing the transport stream before performing error correction by Reed-Solomon code, each packet of the transport stream is composed of a high-layer packet,
Information (hierarchical information) indicating which of the lower hierarchical packets belongs is extracted.

In parallel with this operation, after decoding the Reed-Solomon code of the transport stream, the errors of the high-layer packet and the low-layer packet included in the transport stream are corrected using the Reed-Solomon code. At the same time, when there is a high-layer packet or a low-layer packet whose error cannot be corrected by this error correction processing, information (error information) of the high-layer packet or the low-layer packet whose error could not be corrected is generated.

Next, the transport stream after error correction using the Reed-Solomon code obtained in the Reed-Solomon decoding process, error information for each packet, hierarchical information for each packet, and the like are used. In addition, a transmission signal in a format suitable for cable television is generated, and the transmission signal is modulated and transmitted over the cable 2 to be received by each of the receiving devices 3.

Each receiving device 3 demodulates the transmission signal received via the cable 2 as shown in FIG. 4, and as shown in FIG. A reception demodulation unit 9 for reproducing a frame header and a transmission signal in which the first to Mth slots are arranged);
A transmission line decoding unit 10 for decoding a transmission signal output from the transmission line to reproduce a transport stream, error information, layer information for each packet, and the like, and a transmission line decoding unit 1
Based on the error information for each packet output from 0, the layer information for each packet, and the like, determine the packet error rate of a higher-layer packet, and check whether the packet error rate exceeds a preset threshold. Judge whether
An error rate estimating unit 11 that generates high-layer packet pass / fail judgment information based on the judgment result, high-layer packet pass / fail judgment information output from the error rate estimating unit 11, service specification information (high A control unit 12 for generating an invalidation instruction for invalidating a high-layer packet, a high-layer service selection instruction, a low-layer service selection instruction, and the like, based on, for example, a layer service or a low-layer service. ing.

Further, each receiving device 3 captures the high-layer packet and the low-layer packet output from the transmission path decoding unit 10 and, when an invalidation instruction is output from the control unit 12, performs the transmission path decoding. Based on the layer information for each packet output from the unit 10, the position of the high-layer packet is specified, all the high-layer packets are replaced with null packets, and no invalidation instruction is output from the control unit 12. At this time, based on the error information for each packet output from the transmission path decoding unit 10, the layer information for each packet, etc., the position of the high-layer packet with a high error rate is specified, and On the other hand, a high-layer packet invalidation processing unit that performs a pre-designated compensation process, for example, a process of replacing with a null packet, and the high-layer packet invalidation processing unit 13 High layer packets force, fetches a low layer packet, when the control unit 12 low hierarchical service selection instruction is output, discard the high layer packets has become a null packet, MPEG (the Moving
Picture Experts Group: Color Video Coding Method 1
1) In the decoding method, only the lower layer packet is decoded to reproduce a video signal, an audio signal, and the like.
When the high-layer service selection instruction is output from the, an MPEG decoder unit 14 that discards the low-layer packet, decodes only the high-layer packet by the MPEG decoding method, and reproduces a video signal, an audio signal, and the like. It has.

When the viewer selects a low-layer service and outputs an invalidation instruction and a low-layer service selection instruction from the control unit 12, the transmission signal supplied through the cable 2 is received. While demodulating and reproducing the transmission signal in which the frame header and the first to M-th slots are arranged, the transmission signal is decoded to reproduce the transport stream, error information, layer information for each packet, and the like, Furthermore, based on the layer information for each packet obtained in this reproduction processing, the positions of the high-layer packets and low-layer packets included in the transport stream are specified, and only the high-layer packets are replaced with null packets.
In the MPEG decoding method, only low-level packets are decoded to reproduce video signals, audio signals, and the like.

Thus, when the low-layer service is selected by the viewer, the probability that the high-layer packet for the high-layer service is erroneously recognized as the low-layer packet is reduced, and the low-layer service is not adversely affected. And quality deterioration can be reduced.

When a high-layer service is selected by the viewer and a high-layer service selection instruction is output from the control unit 12, the transmission signal supplied via the cable 2 is received and demodulated to obtain a frame header. , While reproducing the transmission signal in which the first to M-th slots are arranged, the transmission signal is decoded to reproduce the transport stream, the error information, the layer information for each packet, and the like. Based on the hierarchical information for each packet
Higher-layer packets included in the transport stream,
After specifying the position of the low-layer packet, all the low-layer packets are discarded, and only the error-free high-layer packet is decoded by the MPEG decoding method to reproduce a video signal, an audio signal, and the like.

At this time, if the error rate of the high-layer packet is high, processing such as error concealment is performed to increase the time rate of the high-layer service and suppress the quality degradation to a small level.

As described above, in this embodiment, the retransmitting device 4 receives a transport stream such as a BS digital broadcast and discriminates the modulation scheme of the high-layer packet and the low-layer packet constituting the transport stream. Without adding error information of each layer,
At the same time, the high-layer packet, the low-layer packet, and the error information of each layer transmitted on the cable 2 are received by each receiving device 3 and the error information of each layer is used. A high-layer packet can be null-packeted so that even if the high-layer packet is wrong, this does not adversely affect the low-layer packet, while decoding the high-layer packet or the low-layer packet, Alternatively, since the program provided by the low-layer service is viewed, the retransmission device 4 receives the transport stream on which the layer transmission service is performed, and modulates the high-layer packet modulation method and the low-layer packet. When retransmitting to each receiving device 3 side without distinguishing from the modulation method of the packet, Even when scan side error rate is high, it is possible to not adversely affect the low hierarchical service side.

Also, in this embodiment, when the retransmitting device 4 retransmits the high-layer packet and the low-layer packet to each receiving device 3 side, the high-layer packet and the low-layer packet whose error cannot be corrected by the Reed-Solomon code. Each receiver 3 adds error information indicating the position of the hierarchical packet and the like.
And the receiving device 3 calculates the error rate of the high-layer packet and the low-layer packet. When the error rate of the high-layer packet is small, either the high-layer service or the low-layer service is performed. When the error rate of the high-layer packet is large, the low-layer service is selected, so that the optimum layer service can be selected according to the error rate of the high-layer packet. Even if the error rate on the service side is increased, it is possible to prevent the lower layer service side from being adversely affected.

Further, in the above-described embodiment, the format shown in FIG. 3 is used as the format of the transmission signal transmitted and received between the retransmitting device 4 and each of the receiving devices 3, but a format other than such a format is used. For example, as shown in FIG. 5, in order to indicate a lower layer packet, "transport_
priority ”(information indicating the priority of each packet)
To write “1” and indicate a higher layer packet, “tr”
“0” is written to “ansport_priority”, and when Reed-Solomon decoding cannot be performed, “transport_error_indi
"1" is written to "cator", and when Reed-Solomon decoding is completed, "transport_error_indicator" is written to
A transmission signal in which “0” is written may be used.

Even when such a transmission signal is used, similarly to the above-described embodiment, the retransmission device 4 causes the transport stream in which the hierarchical transmission service is performed to be received, and the modulation scheme of the high-layer packet is changed. When retransmission is performed by each receiving apparatus 3 without distinguishing the modulation scheme of the low-layer packet, even if the error rate of the high-layer service increases, the low-layer service is not adversely affected. Can be made.

In the above-described embodiment, a single transport stream may be transmitted by one carrier, or a plurality of transport streams may be transmitted by one carrier.

[0042]

As described above, according to the present invention, the transport stream retransmitting apparatus according to claim 1 receives a transport stream in which a hierarchical transmission service is performed, and modulates a high-layer packet modulation scheme. When each receiving apparatus is retransmitted without making a distinction from the modulation scheme of the low-layer packet, each receiving apparatus can identify whether the packet is a high-layer packet or a low-layer packet.

In the transport stream retransmitting apparatus according to the second aspect, the transport stream in which the hierarchical transmission service is performed is received, and the modulation scheme of the high-layer packet and the modulation scheme of the low-layer packet are not distinguished. When each receiving apparatus is retransmitted, each receiving apparatus can identify the presence or absence of an error for each packet.

According to a third aspect of the present invention, a retransmission apparatus that receives a transport stream in which a hierarchical transmission service is provided transmits a modulation scheme for a high-layer packet and a modulation scheme for a low-layer packet. Is retransmitted without distinction, even if the error rate on the high-layer service side is high, by performing the invalidation processing of the high-layer packet, without being affected by the error rate on the high-layer service side , Can receive low-tier services.

In the transport stream receiving apparatus according to the fourth aspect, the retransmission apparatus receiving the transport stream in which the hierarchical transmission service is performed receives the modulation scheme of the high-layer packet and the modulation scheme of the low-layer packet. Are retransmitted indiscriminately, higher layer packets,
By calculating the error rate of the lower layer packet, the optimum layer service can be selected automatically or manually, and even if the error rate of the higher layer service increases, the lower layer packet is not affected. Service is available.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an embodiment of a retransmission device according to the present invention.

FIG. 2 is a block diagram illustrating an example of a transport stream retransmission / reception system using a transport stream retransmission device and a reception device according to the present invention.

FIG. 3 is an explanatory diagram illustrating a format example of a transmission signal used between a retransmission device and each reception device.

FIG. 4 is a block diagram showing an embodiment of a receiving device according to the present invention.

FIG. 5 is an explanatory diagram showing another format example of a transmission signal used between a retransmission device and each reception device.

[Explanation of symbols]

 1: Transport stream retransmission / reception system 2: Cable 3: Reception device 4: Retransmission device 5: Hierarchical transmission reception demodulation unit 6: Reed-Solomon decoding unit 7: Transmission line coding unit 8: Modulation unit 9: Reception demodulation unit 10 : Transmission path decoding unit 11: Error rate estimation unit 12: Control unit 13: Higher layer packet invalidation processing unit 14: MPEG decoder unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 7/08 H04N 7/10 7/081 7/08 Z 7/10 7/13 A 7/24 (72 Inventor Kimiyuki Koyamada 1-10-11 Kinuta, Setagaya-ku, Tokyo Japan Broadcasting Research Institute (72) Inventor Kiyoshi Murakami 1-10-11 Kinuta, Setagaya-ku, Tokyo Japan Broadcasting Technology Research In-house F-term (reference) 5C025 AA06 AA30 BA22 BA25 BA28 5C059 KK00 KK01 MA00 MA31 RB02 RB17 RC11 RF04 SS02 TA39 TB17 TC22 TD12 UA01 UA05 5C063 AA01 AB03 AB07 AB09 AC01 CA23 CA27 CA36 DA07 DA13 AC13BA13 BC BD08 BD09 BD14 5K028 BB05 BB06 CC02 CC05 KK01 KK03 KK05 KK12 KK32 LL12 MM05 MM08 MM12 PP12 RR02

Claims (4)

[Claims] After receiving a transport stream in which a hierarchical transmission service is performed, each receiving apparatus retransmits the transport stream without distinguishing a modulation scheme between a high-layer packet and a low-layer packet included in the transport stream. In a transport stream retransmitting apparatus for transmitting, when retransmitting a transport stream, information indicating whether each packet constituting the transport stream is a high-layer packet or a low-layer packet is generated and received. Means for transmitting to a device, a transport stream retransmitting device. 2. After receiving a transport stream in which a hierarchical transmission service is performed, each receiving apparatus retransmits the transport stream without distinguishing a modulation scheme between a high-layer packet and a low-layer packet included in the transport stream. In the transport stream retransmitting device for transmitting, when retransmitting the transport stream, for each packet constituting the transport stream, means for generating error information indicating the presence or absence of an error and transmitting the error information to each receiving device; A transport stream retransmitting device comprising: 3. A retransmission apparatus that receives a transport stream in which a layer transmission service is provided, retransmits the data without recognizing a modulation scheme between a high-layer packet and a low-layer packet included in the transport stream. A receiving device that receives the transmitted transmission signal and decodes a high-layer packet or a low-layer packet, when a low-layer service is selected, based on the layer information transmitted from the retransmission device, Means for invalidating the high-layer packets of the transport stream obtained by receiving and decoding the low-layer packets, the transport stream receiving apparatus comprising: 4. A retransmission apparatus that receives a transport stream in which a layer transmission service is provided, retransmits the data without recognizing a modulation scheme between a high-layer packet and a low-layer packet included in the transport stream. A receiving device that receives the transmitted signal and decodes a high-layer packet or a low-layer packet, based on error information for each packet transmitted from the retransmission device, calculates an error ratio for each packet. Means for selecting a layer and decoding a high-layer packet or a low-layer packet.