KR100917214B1 - Receiving system and method of processing data in receiving system - Google Patents

Abstract

The present invention relates to a reception system and a data processing method that are resistant to errors when receiving mobile service data. To this end, the present invention performs additional encoding on the mobile service data and transmits it. By doing so, it is possible to robustly cope with fast channel changes while giving robustness to the mobile service data.

Mobile, Channel Equalization, Base Data

Description

Receiving system and method of processing data in receiving system}

The present invention relates to a digital broadcasting system and a data processing method for transmitting and receiving digital broadcasting.

In the digital broadcasting, VSB (Vestigial Sideband) transmission method adopted as a digital broadcasting standard in North America and Korea is a single carrier method, so the reception performance of the receiving system may be degraded in a poor channel environment.

In particular, in the case of a portable or mobile broadcast receiver, since the robustness against channel change and noise is further required, when the mobile service data is transmitted through the VSB transmission method, the reception performance is further deteriorated.

Accordingly, an aspect of the present invention is to provide a digital broadcasting system and a data processing method that are resistant to channel variation and noise.

The present invention provides a digital broadcasting system and a data processing method for improving the reception performance of a reception system by performing additional encoding on mobile service data and transmitting the same to a reception system.

The present invention provides a digital broadcasting system and a data processing method for improving the reception performance of a reception system by inserting and transmitting known data known by a promise of a transmission / reception side into a predetermined area of a data area.

The present invention provides an apparatus and method for equalizing a channel using field synchronization and known data in a receiving system.

In order to achieve the above object, a transmission system according to an embodiment of the present invention may include a service multiplexer and a transmitter. The service multiplexer may multiplex the mobile service data and the main service data at a preset data rate and transmit them to the transmitter. The transmitter may perform additional encoding on mobile service data transmitted from the service multiplexer, and collect a plurality of mobile service data packets on which encoding is performed to form a data group. The transmitter may multiplex a mobile service data packet including mobile service data and a main service data packet including main service data in packet units and transmit the packet to a receiving system. In this case, the transmitter may multiplex the data group and the main service data packet into a burst structure, and the burst may be divided into a burst on period including a data group and a burst off period without a data group.

The data group may be divided into a plurality of areas according to the degree of interference of the main service data. Long known data streams may be inserted periodically in an area free of interference of the main service data.

A receiving system according to an embodiment of the present invention may use the known data stream for demodulation and channel equalization.

The channel equalizer according to the present invention may perform channel equalization in different ways according to the characteristics of each region in the data group divided into a plurality of regions.

When the reception system receives only mobile service data, the reception system may power on only in the burst on period to process mobile service data.

To this end, a reception system according to an embodiment of the present invention may include a known data detector, a frequency domain converter, a CIR estimator, a CIR calculator, a coefficient calculator, and a distortion compensator. The known data detector may detect known data positions, field sync positions from a group of data received, including at least field sync, known data, and mobile service data. The frequency domain converter may convert data in the data group into a frequency domain. The CIR estimator may estimate a channel impulse response (CIR) using data received during field synchronization and known data intervals and reference data generated at the receiver according to the known data position and field sync position information. The CIR calculator may interpolate or extrapolate a channel impulse response (CIR) estimated by the CIR estimator according to characteristics of each region in the received data group. The coefficient calculator may calculate an equalization coefficient after converting a channel impulse response (CIR) output from the CIR calculator into a frequency domain. The distortion compensator may compensate for the channel distortion by multiplying the equalization coefficient of the coefficient calculator by the data converted from the frequency domain converter to the frequency domain.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

The digital broadcasting system and the data processing method according to the present invention are advantageous in that they are resistant to errors and compatible with existing receivers when transmitting mobile service data through a channel.

The present invention has the advantage that the mobile service data can be received without error even in a ghost and noisy channel.

The present invention can improve the reception performance of the reception system in an environment with a high channel change by inserting and transmitting known data in a specific position of the data area.

The present invention can reduce the power of the reception system by multiplexing the mobile service data into a burst structure when multiplexing the mobile service data with the main service data.

In the reception system of the present invention, channel equalization is performed by using known data information, so that channel equalization can be stably performed.

In particular, by performing channel equalization in a different manner according to the characteristics of each region in the data group divided into a plurality of regions, it is possible to more stably perform channel equalization in each region to further improve reception performance.

The present invention is more effective when applied to portable and mobile receivers that require severe channel changes and robustness against noise.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention that can specifically realize the above object will be described. At this time, the configuration and operation of the present invention shown in the drawings and described by it will be described as at least one embodiment, by which the technical spirit of the present invention and its core configuration and operation is not limited.

Definition of terms used in the present invention

The terms used in the present invention were selected as widely used general terms as possible in consideration of the functions in the present invention, but may vary according to the intention or custom of the person skilled in the art or the emergence of new technologies. In addition, in certain cases, there is a term arbitrarily selected by the applicant, and in this case, the meaning will be described in detail in the corresponding description of the invention. Therefore, it is intended that the terms used in the present invention should be defined based on the meanings of the terms and the general contents of the present invention rather than the names of the simple terms.

Among the terms used in the present invention, the main service data is data that can be received by the fixed receiving system and may include audio / video (A / V) data. That is, the main service data may include A / V data of a high definition (HD) or standard definition (SD) level, and may include various data for data broadcasting. Known data is data known in advance by an appointment of the transmitting / receiving side.

In addition, the mobile service data in the present invention includes at least one of the mobile (Mobile) data, the service data (Pedestrian), handheld (Handheld) service data, in the present invention for convenience of description This is called service data. In this case, the mobile service data may include not only M / P / H (Mobile / Pedestrian / Handheld) service data, but also any service data indicating movement or portability. Accordingly, the mobile service data may include the M / P / H. It will not be limited to service data.

The mobile service data defined as described above may be data having information such as a program execution file, stock information, or the like, or may be A / V data. In particular, the mobile service data may be A / V data having a smaller resolution and a smaller data rate than the main service data as service data for a portable or mobile terminal (or broadcast receiver). For example, if the A / V codec used for the existing main service is an MPEG-2 codec, the MPEG-4 codec that has better image compression efficiency as the A / V codec for mobile services. AVC (Advanced Video Coding), SVC (Scalable Video Coding), etc. may be used. In addition, any kind of data may be transmitted as the mobile service data. For example, TPEG (Transport Protocol Expert Group) data for broadcasting traffic information in real time may be serviced.

In addition, data services using the mobile service data include weather services, transportation services, securities services, viewer participation quiz program, real-time polls, interactive educational broadcasting, game services, drama plot, characters, background music, shooting location, etc. Informational services, information on past sports history, profile and performance of athletes, and information on programs by media, time, or subject that enables product information and ordering. Etc., but the present invention is not limited thereto.

The transmission system of the present invention enables multiplexing of main service data and mobile service data on the same physical channel without backward affecting the reception of main service data in an existing receiving system.

The transmission system of the present invention performs additional encoding on mobile service data and inserts and transmits data that is known in advance to both the transmitting and receiving sides, that is, known data.

When the transmission system according to the present invention is used, the reception system enables mobile reception of mobile service data, and also enables stable reception of mobile service data against various distortions and noises generated in a channel.

Schematic description of the transmission system

1 is a schematic diagram showing an embodiment of a transmission system for applying the present invention, and may include a service multiplexer 100 and a transmitter 200.

Here, the service multiplexer 100 is located in a studio of each broadcasting station, and the transmitter 200 is located in a site away from the studio. In this case, the transmitter 200 may be located in a plurality of different areas. In one embodiment, the plurality of transmitters may share the same frequency, in which case the plurality of transmitters all transmit the same signal. In the receiving system, the channel equalizer can then recover the original signal by compensating for the signal distortion caused by the reflected wave. In another embodiment, the plurality of transmitters may have different frequencies for the same channel.

Various methods may be used for data communication between the service multiplexer and each transmitter located at a remote location, and as an example, an interface standard such as Synchronous Serial Interface for transport of MPEG-2 data (SMPTE-310M) may be used. . In the SMPTE-310M interface standard, the output data rate of the service multiplexer is determined to be a constant data rate. For example, it is set at 19.39 Mbps for 8VSB, and 38.78 Mbps for 16VSB. In addition, the conventional 8VSB type transmission system can transmit a transport stream (TS) packet having a data rate of about 19.39 Mbps on one physical channel. In the transmitter according to the present invention having backward compatibility with the existing transmission system, the mobile service data is further encoded and then multiplexed in the form of the main service data and the TS packet, and the data of the multiplexed TS packet is transmitted. The rate is about 19.39 Mbps.

In this case, the service multiplexer 100 receives at least one type of mobile service data and program specific information (PSI) / program and system information protocol (PSIP) table data for each mobile service, respectively, and transports a transport stream (TS) packet. Encapsulation. In addition, the service multiplexer 100 receives at least one kind of main service data and PSI / PSIP table data for each main service and encapsulates them into TS packets. Subsequently, the TS packets are multiplexed according to a preset multiplexing rule and output to the transmitter 200.

Service multiplexer

FIG. 2 is a detailed block diagram illustrating an embodiment of the service multiplexer. The controller 110 controls overall operation of the service multiplexer, a PSI / PSIP generator 120 for a main service, and a mobile service. The PSI / PSIP generator 130 may include a null packet generator 140, a mobile service multiplexer 150, and a transport multiplexer 160.

The transport multiplexer 160 may include a main service multiplexer 161 and a transport stream (TS) packet multiplexer 162.

Referring to FIG. 2, at least one kind of compressed coded main service data and PSI / PSIP table data generated by the PSI / PSIP generator 120 for the main service are included in the main service multiplexer of the transport multiplexer 160. 161). The main service multiplexer 161 encapsulates input main service data and PSI / PSIP table data in the form of MPEG-2 TS packets, respectively, and multiplexes these TS packets to form a TS packet multiplexer 162. Will output The data packet output from the main service multiplexer 161 will be referred to as a main service data packet for convenience of description.

In addition, at least one type of compressed-coded mobile service data and PSI / PSIP table data generated by the PSI / PSIP generator 130 for the mobile service are input to the mobile service multiplexer 150.

The mobile service multiplexer 150 encapsulates input mobile service data and PSI / PSIP table data in the form of MPEG-2 TS packets, respectively, and multiplexes these TS packets to form a TS packet multiplexer 162. Will output The data packet output from the mobile service multiplexer 150 will be referred to as a mobile service data packet for convenience of description.

In this case, identification information is required for the transmitter 200 to process the main service data packet and the mobile service data packet separately. The identification information may use a predetermined value by an appointment of a transmitting / receiving side, may be configured as separate data, or may be used by modifying a value of a predetermined position in the data packet.

According to an embodiment of the present invention, different PIDs (Packet Identifiers) may be allocated to the main service data packet and the mobile service data packet.

In another embodiment, by modifying the sync byte in the header of the mobile service data packet, the sync byte value of the corresponding service data packet may be used to distinguish. For example, the sync byte of the main service data packet outputs the value defined in ISO / IEC13818-1 (for example, 0x47) without modification, and the sync byte of the mobile service data packet is modified and outputted. Data packets can be distinguished from mobile service data packets. On the contrary, by modifying the sync byte of the main service data packet and outputting the sync byte of the mobile service data packet as it is, the main service data packet and the mobile service data packet can be distinguished.

There may be various ways to modify the sync byte. For example, the sync byte may be inverted bit by bit or only some bits may be inverted.

As such, any identification information capable of distinguishing the main service data packet from the mobile service data packet may be used. Thus, the present invention will not be limited to the above-described embodiments.

Meanwhile, the transport multiplexer 160 may use the transport multiplexer used in the existing digital broadcasting system. That is, in order to transmit the mobile service data multiplexed with the main service data, the data rate of the main service is limited to a data rate of (19.39-K) Mbps, and the K Mbps corresponding to the remaining data rate is allocated to the mobile service. This allows you to use the transport multiplexer that is already in use without changing it.

The transport multiplexer 160 multiplexes the main service data packet output from the main service multiplexer 161 and the mobile service data packet output from the mobile service multiplexer 150 to transmit to the transmitter 200.

However, there may occur a case where the output data rate of the mobile service multiplexer 150 is not K Mbps. In this case, the mobile service multiplexer 150 multiplexes and outputs null data packets generated by the null packet generator 140 such that the output data rate is K Mbps. That is, the null packet generator 140 generates a null data packet and outputs it to the mobile service multiplexer 150 in order to constantly adjust the output data rate of the mobile service multiplexer 150.

For example, if the service multiplexer 100 allocates K Mbps of 19.39 Mbps to mobile service data and allocates the remaining (19.39-K) Mbps to main service data, the service multiplexer 100 is actually assigned. The data rate of the mobile service data multiplexed at < RTI ID = 0.0 > This is because, in the case of the mobile service data, the amount of data is increased by performing additional encoding in a pre-processor of the transmitter. As a result, the data rate of mobile service data that can be transmitted by the service multiplexer 100 becomes smaller than K Mbps.

For example, the preprocessor of the transmitter performs encoding at least 1/2 code rate on the mobile service data, so that the amount of output data of the preprocessor is more than twice the amount of input data. Therefore, the sum of the data rate of the main service data multiplexed in the service multiplexer 100 and the data rate of the mobile service data is always less than or equal to 19.39 Mbps.

Accordingly, in order to adjust the final output data rate output from the service multiplexer 100 to a constant data rate (for example, 19.39 Mbps), the null packet generator 140 generates a null data packet by a data rate that is short. Output to mobile service multiplexer 150.

Then, the mobile service multiplexer 150 encapsulates the input mobile service data and PSI / PSIP table data in the form of MPEG-2 TS packets, respectively, and multiplexes the TS packets and null data packets. Output to the packet multiplexer 162.

The TS packet multiplexer 162 multiplexes the main service data packet output from the main service multiplexer 161 and the mobile service data packet output from the mobile service multiplexer 150 to the transmitter 200 at a 19.39 Mbps data rate. send.

According to an embodiment of the present invention, the mobile service multiplexer 150 receives a null data packet. This is only one embodiment. In another embodiment, the TS packet multiplexer 162 receives a null data packet and adjusts the final data rate to a constant data rate. The output path and the multiplexing rule of the null data packet are controlled by the controller 110. The controller 110 controls the multiplexing and null packet generators 140 in the mobile service multiplexer 150, the main service multiplexer 161 of the transport multiplexer 160, and the TS packet multiplexer 162. Control the generation of null data packets.

At this time, the transmitter 200 discards the null data packet transmitted from the service multiplexer 100 without transmitting it to the receiving system.

In order to discard the null data packet without transmitting the transmitter 200, identification information for distinguishing the null data packet is required. The identification information for distinguishing the null data packet may use a value predetermined by an appointment of the transmitting / receiving side or may be configured as separate data. For example, the sync byte value in the header of the null data packet may be modified to be used as identification information, or a transport_error_indicator flag may be used as identification information.

According to an embodiment of the present invention, the transport_error_indicator flag of a header in a null data packet is used as identification information for distinguishing a null data packet. In this case, the transport_error_indicator flag of the null data packet is set to 1, and the transport_error_indicator flag of all data packets other than the null data packet is reset to 0 to distinguish the null data packet. That is, when the null packet generator 140 generates a null data packet, if the transport_error_indicator flag is set to '1' in the field of the header of the null data packet and transmitted, the transmitter 200 may separate the discard packet.

The identification information for distinguishing the null data packet may be any one capable of distinguishing the null data packet, and thus the present invention will not be limited to the above-described embodiments.

In another embodiment, the present invention provides a transmission parameter in at least a portion of the null data packet, or at least one table of a PSI / PSIP table for a mobile service, or an Operations and Maintenance (OM) packet (or OMP). May be included. In this case, the transmitter 200 extracts the transmission parameter and outputs the transmission parameter to the corresponding block, and transmits the transmission parameter to the receiving system if necessary.

That is, a packet called OMP (Operations and Maintenance Packet) is defined for the purpose of operation and management of the transmission system. As an example, the OMP follows the format of an MPEG-2 TS packet and its PID has a value of 0x1FFA. The OMP consists of a header of 4 bytes and a payload of 184 bytes. The first byte of the 184 bytes indicates the type of the OM packet as the OM_type field.

In the present invention, the transmission parameter may be transmitted in an OMP format. In this case, the transmitter 200 may inform the transmitter 200 that the transmission parameter is transmitted to the OMP using a predetermined value among unused field values of the OM_type field. That is, the transmitter 200 may find the OMP by looking at the PID, and parse the OM_type field in the OMP to determine whether the transmission parameter is included after the OM_type field of the corresponding packet.

The transmission parameter is additional information necessary for processing mobile service data in a transmission / reception system. For example, the transmission parameter includes data group information, region information in a data group, RS frame information, super frame information, and burst information. , Turbo code information, RS code information, and the like. The burst information may include burst size information, burst period information, time until the next burst, and the like. The burst period means a period in which bursts transmitting the same type of mobile service are repeated, and the burst size means the number of data groups included in one burst. The data group includes a plurality of mobile service data packets, and these data groups are gathered to form a burst. The burst section means the start of the current burst to the start of the next burst, a section including a data group (also called a burst on section) and a section without a data group (or a burst off section). It may be referred to as). One burst on interval consists of a plurality of fields, one field includes one data group.

In addition, the transmission parameter includes information on how signals in a symbol region are encoded to transmit mobile service data, and multiplexing information on how to be multiplexed between main service data and mobile service data or various types of mobile service data. May be included.

The information included in the transmission parameter is only one embodiment for better understanding of the present invention, and the present invention is not limited to the above embodiment because addition and deletion of information included in the transmission parameter can be easily changed by those skilled in the art. Will not.

In addition, the transmission parameters may be provided from the service multiplexer 100 to the transmitter 200, or the transmitter 200 itself may be set by a controller (not shown) or received externally.

transmitter

3 is a block diagram illustrating a transmitter 200 according to an embodiment of the present invention, a demultiplexer 210, a packet jitter mitigator 220, and a pre-processor 230. , A packet multiplexer 240, a post-processor 250, a sync multiplexer 260, and a transmission unit 270.

When the data packet is received from the service multiplexer 100, the demultiplexer 210 must distinguish whether the received data packet is a main service data packet, a mobile service data packet, or a null data packet.

In one embodiment, the demultiplexer 210 may distinguish between the mobile service data packet and the main service data packet using a PID in the received data packet, and may distinguish a null data packet using a transport_error_indicator field.

The main service data packet separated by the demultiplexer 210 is output to the packet jitter reducer 220, the mobile service data packet is output to the preprocessor 230, and the null data packet is discarded. If the null data packet includes a transmission parameter, the null data packet is discarded after the transmission parameter is extracted and output to the corresponding block.

The preprocessor 230 may be located at any particular location according to the use of data to be further encoded and transmitted on the data frame for the mobile service data in the mobile service data packet which is demultiplexed and output from the demultiplexer 210. Perform the data group formation process to make it possible. This is to allow the mobile service data to respond quickly and strongly to noise and channel changes. The preprocessor 230 may refer to the transmission parameter in further encoding. In addition, the preprocessor 230 collects a plurality of mobile service data packets to form a data group, and allocates known data, mobile service data, RS parity data, MPEG header, and the like to a predetermined region in the data group.

Preprocessor in the transmitter

4 is a block diagram illustrating an embodiment of a preprocessor 230 according to the present invention, which includes a data randomizer 301, an RS frame encoder 302, a block processor 303, a group formatter 304, and data. A deinterleaver 305, and a packet formatter 306.

The data randomizer 301 in the preprocessor 230 configured as described above renders the mobile service data packet including the mobile service data input through the demultiplexer 210 and outputs it to the RS frame encoder 302. In this case, by performing the randomization on the mobile service data in the data randomizer 301, the data randomizer 251 of the postprocessor 250 may omit the randomizing process on the mobile service data. The data randomizer 301 may perform randomizing by discarding sync bytes in the mobile service data packet. Alternatively, rendering may be performed without discarding the sync byte, which is a designer's option. According to an embodiment of the present invention, the rendering is performed without discarding the sync byte in the corresponding mobile service data packet.

The RS frame encoder 302 configures an RS frame by collecting a plurality of randomized and input mobile service data packets and performs at least one of an error correction encoding process and an error detection encoding process in units of RS frames. . This makes it possible to cope with extremely poor and rapidly changing propagation environment by giving robustness to mobile service data and distracting clustering errors that can be caused by the propagation environment change.

In addition, the RS frame encoder 302 may collect a plurality of RS frames to form a super frame, and perform row permutation in units of super frames. The row permutation is also referred to as row interleaving, and in the present invention, it is referred to as row mixing for convenience of description.

That is, when the RS frame encoder 302 mixes each row of the super frame with a predetermined rule, the positions of the rows before and after row mixing in the super frame are changed. When the row mixing is performed in the unit of the super frame, even if a large amount of error occurs in a single RS frame to be decoded, the errors are distributed in the entire super frame, so that these errors are distributed throughout the super frame. The decryption ability is improved.

According to an embodiment of the present invention, the RS frame encoder 302 uses RS coding for error correction coding and cyclic redundancy check (CRC) coding for error detection coding. Parity data to be used for error correction is generated when the RS encoding is performed, and CRC data to be used for error detection is generated when CRC encoding is performed.

The RS coding is one of forward error correction (FEC). The FEC refers to a technique for correcting an error occurring in a transmission process. The CRC data generated by the CRC encoding may be used to indicate whether mobile service data is damaged by an error while being transmitted through a channel. The present invention may use other error detection encoding methods in addition to CRC encoding, or may increase the overall error correction capability at the receiving end by using an error correction encoding method.

In this case, the RS frame encoder 302 refers to a transmission parameter set in advance and / or a transmission parameter provided by the service multiplexer 100 in order of RS frame configuration, RS encoding, CRC encoding, super frame configuration, and super frame unit. Raw mixing and the like.

In the preprocessor RS  Frame encoder

5A to 5E illustrate an embodiment of an encoding process of an RS frame encoder 302 according to the present invention.

That is, the RS frame encoder 302 first divides the input mobile service data byte into predetermined length units. The predetermined length is a value determined by a system designer. In the present invention, 187 bytes is described as an embodiment, and for convenience of description, the 187 byte unit will be referred to as a packet.

For example, if the mobile service data input as shown in (a) of FIG. 5 is an MPEG transport stream (TS) packet configured in units of 188 bytes, the first sync byte is removed to 187 bytes as shown in FIG. Configure one packet. The reason for removing the sync byte is that all mobile service data packets have the same value. In this case, the synchronization byte removal may be performed when the data randomizer 301 at the front end is rendered. In this case, the process of removing the sync byte from the RS frame encoder 302 is omitted, and when the sync byte is added by the receiving system, the sync byte may be added by the data de-randomizer instead of the RS frame decoder.

Therefore, if there is no fixed one byte (eg, sync byte) in the mobile service data packet input to the RS frame encoder 302 or the input mobile service data is not in the form of a packet, the input mobile service data Is divided by 187 bytes, and a packet is composed of divided 187 bytes.

Subsequently, as shown in (c) of FIG. 5, N packets of 187 bytes are collected to form one RS frame. In this case, the configuration of one RS frame is achieved by sequentially inserting a packet of 187 bytes in a row direction into an RS frame having a size of N (row) * 187 (column) bytes.

In the present invention, the RS frame thus generated is referred to as a first RS frame for convenience of description. That is, only the pure mobile service data is included in the first RS frame, which is equivalent to 187 rows of N bytes.

When the mobile service data in the RS frame is divided into a predetermined size and then transmitted in the same order as the input order for composing the RS frame, if an error occurs at a specific point in time between transmission and reception, the error occurs on the RS frame. To be gathered. In this case, by using RS erasure decoding in error correction decoding in the receiving system, the error correction capability can be improved.

At this time, all N columns of the RS frame include 187 bytes as shown in FIG.

In this case, Nc-Kc (= P) parity bytes are generated by performing (Nc, Kc) -RS encoding on each column, and the generated P parity bytes are added after the last byte of the column (187). + P) You can create a column of bytes. Here, Kc is 187 as in FIG. 5C, and Nc is 187 + P. For example, if P is 48, (235,187) -RS encoding may be performed to create a column of 235 bytes.

When the RS encoding process is performed on all N columns of FIG. 5C, an RS frame having a size of N (row) * (187 + P) (column) bytes as shown in FIG. 5D is obtained. I can make it. In the present invention, for convenience of description, an RS frame to which RS parity is added is also referred to as a second RS frame. That is, the second RS frame is equivalent to 187 + P rows of N bytes.

As shown in (c) or (d) of FIG. 5, each row of the RS frame includes N bytes. However, an error may be included in the RS frame according to the channel condition between the transmission and reception. When an error occurs in this way, it is possible to use CRC data (or CRC code or CRC checksum) to check an error for each row.

The RS frame encoder 302 may perform CRC encoding on the RS coded mobile service data to generate the CRC data. The CRC data generated by the CRC encoding may be used to indicate whether mobile service data is damaged by an error while being transmitted through a channel.

The present invention may use other error detection encoding methods in addition to CRC encoding, or may increase the overall error correction capability at the receiving end by using an error correction encoding method.

5 (e) shows an example of using a 2-byte (ie 16-bit) CRC checksum as CRC data. It is adding. By doing this, each row is expanded to N + 2 bytes.

Equation 1 below shows an example of a polynomial that generates a 2-byte CRC checksum for each row of N bytes.

g (x) = x ¹⁶ + x ¹² + x ⁵ + 1

Since adding a 2-byte CRC checksum to each row is an embodiment, the present invention will not be limited to the example described above.

In the present invention, for convenience of description, an RS frame to which an RS parity and a CRC checksum are added may be referred to as a third RS frame. That is, the third RS frame is equivalent to 187 + P rows of N + 2 bytes.

After all the RS coding and CRC coding described above, an RS frame of N * 187 bytes is extended to an RS frame of (N + 2) * (187 + P) bytes.

The expanded RS frame is input to the block processor 303 as shown in FIG.

The mobile service data encoded by the RS frame encoder 302 as described above is input to the block processor 303.

The block processor 303 encodes the input mobile service data at a G / H (where G <H) code rate and outputs the encoded code to the group formatter 304.

That is, the block processor 303 divides the mobile service data input in byte units into bits, encodes the divided G bits into H bits, and converts them into byte units and outputs them. For example, if one bit of input data is encoded into two bits and outputted, G = 1 and H = 2. If one bit of input data is encoded into four bits and outputted, G = 1 and H = 4. In the present invention, for convenience of description, the former is referred to as encoding at 1/2 code rate (or sometimes referred to as 1/2 encoding), and the latter is referred to as encoding at 1/4 code rate (or referred to as 1/4 encoding). do.

In the case of using the 1/4 encoding, it is possible to have a high error correction capability because of the higher code rate than the 1/2 encoding. For this reason, the data encoded at the 1/4 code rate in the later group formatter 304 is allocated to an area where reception performance may be deteriorated, and the data encoded at 1/2 code rate may have better performance. If we assign to, we can get the effect of reducing the difference in performance.

In this case, the block processor 303 may also receive signaling information including a transmission parameter, and the signaling information also performs 1/2 encoding or 1/4 encoding as in the mobile service data processing process. The signaling information is also regarded as mobile service data and processed.

Meanwhile, the group formatter 304 inserts the mobile service data output from the block processor 303 into a corresponding region in the data group formed according to a predefined rule, and also stores various position holders or the like in relation to data deinterleaving. Known data (or known data position holders) are also inserted into the corresponding area in the data group.

In this case, the data group may be divided into at least one layered area, and the type of mobile service data inserted into each area may vary according to characteristics of each layered area. For example, each region may be classified based on reception performance in a data group. One data group also includes field synchronization.

According to an embodiment of the present invention, one data group is divided into A, B, and C regions based on the data structure after data interleaving. In this case, the group formatter 304 may allocate the mobile service data input by RS coding and block coding to the corresponding region with reference to the transmission parameter.

FIG. 6A illustrates a form in which data after data interleaving is listed separately, and FIG. 6B illustrates a form in which data before data interleaving is separately listed. At this time, the data structure as shown in FIG. 6A is finally transmitted to the receiving system. That is, one transport packet is interleaved by the data interleaver, distributed by several data segments, and transmitted to the receiving system. In this case, since a packet of 207 bytes has the same amount of data as one data segment, the packet before data interleaving may be used as a concept of a segment.

The data group formed in the structure shown in FIG. 6A is input to the data deinterleaver 305.

FIG. 6A illustrates an example in which a data group is largely divided into three regions, for example, region A, region B, and region C in the data configuration before data deinterleaving. It is showing.

In addition, according to an embodiment of the present invention, the A to C regions are divided into a plurality of sub-regions, respectively.

In FIG. 6A, the A region is divided into five subregions A1 to A5, the B region is divided into two subregions B1 and B2, and the C region is divided into three subregions C1 to C3. An example is shown.

The areas A to C are classified based on areas having similar reception performance in the data group. In this case, the type of mobile service data to be inserted may vary according to characteristics of each region.

In the present invention, dividing the A to C region based on the degree of interference of the main service data will be described as an embodiment.

Here, the reason why the data group is divided into a plurality of areas is used for different purposes. That is, an area where there is no or little interference of the main service data may exhibit stronger reception performance than an area that is not. In addition, in the case of applying a system for inserting and transmitting known data into a data group, an area where there is no interference of main service data (for example, A area) when periodically inserting long known data into a mobile service data periodically It is possible to periodically insert known data of a certain length into the. However, it is difficult to periodically insert known data into the region where the main service data interferes (for example, B and C regions) due to the interference of the main service data, and also to insert long known data continuously.

In this case, the group formatter 304 can improve the reception performance of the reception system by forming a data group including the position where the field synchronization is to be inserted. At this time, the group formatter 304 determines the position where the field sync is to be inserted, and the actual field sync is inserted at the field sync insertion position determined by the group formatter 304 by the sync multiplexer 260 at the rear stage. 6B shows an example of a data structure before data interleaving, in which 118 segments are allocated to one data group. The data group of FIG. 6B shows an embodiment of 118 segments including 38 segments forward and 80 segments backward based on the position at which the field sync is to be inserted.

Next, a specific example in which the areas A (A1 to A5), B (B1 and B2), and C (C1 to C3) are allocated in the data group will be described with reference to FIG. 6A. The size of the data group of FIG. 6A, the number of layered areas and the size of each area in the data group, the number of bytes of mobile service data that can be inserted into each layered area, and the like are one embodiment for describing the present invention.

That is, the area A includes areas A2 to A5 in which long known data sequences in the data group can be periodically inserted and main service data are not mixed. The area A also includes an area A1 between the field synchronization area to be inserted into the data group and the area to which the first known data string is to be inserted.

As an example, in FIG. 6A, mobile service data of 2428 bytes in an A1 area, 2580 bytes in an A2 area, 2772 bytes in an A3 area, 2472 bytes in an A4 area, and 2772 bytes in an A5 area may be inserted. The trellis initialization, known data, MPEG header, RS parity, etc. are excluded from the mobile service data.

In the case of the area A including the field synchronization and the known data sequence as described above, the receiving system can perform equalization using the channel information obtained from the known data and the field synchronization, thereby achieving robust equalization performance.

The B area is a B1 area located in front of the first 8 segments of the field sync area in the data group (temporally located in front of the A1 area), and B2 located within 8 segments after the last known data column inserted into the data group. Region (temporally located behind region A). For example, 930 bytes can be inserted into the B1 region and 1350 bytes of mobile service data can be inserted into the B2 region. Similarly, trellis initialization, known data, MPEG header, RS parity, etc. are excluded from the mobile service data.

In the case of the B region, the receiving system can perform equalization using the channel information obtained in the field synchronization section, and can also perform equalization using the channel information obtained from the last known data sequence. Can respond to changes.

The C area includes the first ninth segment of the field sync area, and includes a C1 area (temporally located in front of the A area) located within 30 segments in front of it, and a ninth segment after the last known data column in the data group. C2 region located within 12 segments (it is located behind A region in time), and C3 region located within 32 segments following said C2 region.

For example, 1272 bytes in the C1 region, 1560 bytes in the C2 region, and 1312 bytes in the C3 region may be inserted. Similarly, trellis initialization, known data, MPEG header, RS parity, etc. are excluded from the mobile service data.

In this case, since the C1 region located in front of the A region in time is far from the field synchronization, which is the closest known data, the receiving system may use channel information obtained from the field synchronization at the time of channel equalization in the receiving system, or the most recent data group. Recent channel information can also be used. In the C2 and C3 regions located behind the A region in time, the equalization may not be perfect when the channel is rapidly changed even if the receiving system uses the channel information obtained from the last known data stream when the channel is equalized. . Therefore, the C region may have lower equalization performance than the B region.

Assuming that a data group is allocated to a plurality of layered areas as described above, the above-described block processor 303 may encode mobile service data to be inserted into each area at different code rates according to the characteristics of the layered area.

For example, the mobile service data to be inserted into areas A1 to A5 in the area A is encoded by the block processor 303 at a 1/2 code rate, and the encoded mobile service data is encoded into the group formatter 304. In the A1 ~ A5 region can be inserted.

The mobile service data to be inserted into the B1 and B2 areas in the B area is encoded by the block processor 303 at a 1/4 code rate with higher error correction capability than the 1/2 code rate. May be inserted into the B1 and B2 regions by the group formatter 304.

The mobile service data to be inserted in the C1 to C3 areas of the C region is encoded by the block processor 303 at a code rate having a 1/4 code rate or a stronger error correction capability than the 1/4 code rate. The coded data may be inserted into the C1 to C3 areas by the group formatter 304, or may be left as a reserved area for later use.

In addition, the group formatter 304 also inserts additional information data, such as signaling, which informs overall transmission information separately from the mobile service data.

In addition to the encoded mobile service data output from the block processor 303, the group formatter 304 may include an MPEG header position holder, an unstructured RS parity position holder, and a main in relation to data deinterleaving at a later stage as shown in FIG. 6A. Insert the service data location holder. The reason for inserting the main service data location holder is that the mobile service data and the main service data are mixed between B and C regions based on the input of the data deinterleaver as shown in FIG. 6A. For example, the position holder for the MPEG header may be assigned to the front of each packet based on the output data after the data deinterleaving.

In addition, the group formatter 304 may insert the known data generated by a predetermined method or insert a known data position holder for inserting the known data later. In addition, an initialization data position holder for initializing the Trellis Encoding Module 256 is inserted into a corresponding region (ie, a red region). In one embodiment, the initialization data location holder may be inserted before the known data stream.

For example, in the data structure as shown in FIG. 6A, five known data areas (ie, blue areas) are allocated to area A in the data group in order to insert known data or known data position holders.

For convenience of description, five known data areas will be referred to as first to fifth known data areas.

The first known data area is allocated at a position about 16 segments away from the position where the field sync is to be inserted, and the second known data area is allocated at a position about 16 segments away from the first known data area. The third known data area is also allocated at a position about 16 segments away from the second known data area, and the fourth known data area is allocated at a position about 16 segments away from the third known data area. Similarly, the fifth known data area is allocated at a position about 16 segments away from the fourth known data area. In this case, the lengths of the first to fifth known data areas may be the same or may be different from each other. According to the present invention, at least one of the first to fifth known data areas is different from one another in length.

In the present invention, inserting known data into the first to fifth known data areas in the group formatter 304 will be described as an embodiment.

In this case, at least one area of the first to fifth known data areas, for example, the first known data area includes the same pattern repeated two or more times in the known data. For convenience of description, the repeated known data pattern will be referred to as a first known data pattern. The first known data pattern may be used for initial carrier frequency synchronization acquisition in a receiving system, or may be used for estimating the field synchronization position or the position of another known data region.

Each of the first to fifth known data areas includes a known data column having the same pattern, and will be referred to as a second known data pattern to distinguish it from the first known data pattern. According to an embodiment of the present invention, the lengths of the first known data pattern and the second known data pattern are different from each other.

The length of the known data string of the second known data pattern and the total known data string of the corresponding known data area may be the same or different. In other cases, the entire known data column is longer than the known data column of the second known data pattern, and the second known data pattern is included in the entire known data column.

In the present invention, 1424 symbols (that is, 356 bytes) are inserted into the first through fifth known data areas in the second known data pattern, respectively. The second known data pattern inserted into the first to fifth known data areas may be used as a training sequence in a receiving system or may be used to estimate a channel impulse response (CIR).

In this case, the mobile service data size that can be inserted into one data group is determined by the size of the trellis initialization position holder, known data (or known data position holder), MPEG header position holder, RS parity position holder, etc. inserted into the data group. Can vary.

The output of the group formatter 304 is input to the data deinterleaver 305, and the data deinterleaver 305 uses the data and position holders in the data group output from the group formatter 304 as a reverse process of data interleaving. The data is deinterleaved and output to the packet formatter 306. That is, when the data and position holder in the data group configured as shown in FIG. 6A are deinterleaved by the data deinterleaver 305, the data group output to the packet formatter 306 has a structure as shown in FIG. 6B.

The packet formatter 306 removes the main service data location holder and the RS parity location holder which have been allocated for deinterleaving among the deinterleaved input data, collects the remaining parts, and then collects null packets in the 4-byte MPEG header location holder. Insert and replace the MPEG header with the PID (or PID not used in the main service data packet).

The packet formatter 306 may also insert the actual known data into the known data position holder when the group formatter 304 inserts the known data position holder, or later inserts the known data position holder for replacement. You can also output without adjustment.

The packet formatter 306 then divides the data in the packet-formatted data group into mobile service data packets (ie, MPEG TS packets) in units of 188 bytes and provides them to the packet multiplexer 240.

The packet multiplexer 240 multiplexes the mobile service data packet output from the preprocessor 230 and the main service data packet output from the packet jitter reducer 220 according to a predefined multiplexing method. Output to the data renderer 251 of the processor 250. The multiplexing method can be adjusted by various variables of the system design.

As one of multiplexing methods of the packet multiplexer 240, a burst section is provided on a time axis, and a plurality of data groups are transmitted in a burst on section within a burst section, and only main service data is transmitted in a burst off section. Can be. The burst period here means from the start of the current burst to the start of the next burst.

In this case, the main service data may be transmitted in the burst on period. The packet multiplexer 240 may know the number, period, etc. of data groups included in one burst with reference to the transmission parameter, for example, a burst size or a burst period.

In this case, the mobile service data and the main service data may be mixed in the burst on section, and only the main service data exists in the burst off section. Accordingly, the main service data section for transmitting the main service data may exist in both the burst on section and the burst off section. In this case, the number of main service data packets included in the main service data section and the burst off section in the burst on section may be different or the same.

As described above, when the mobile service data is transmitted in a burst structure, the receiving system receiving only the mobile service data turns on power only in the burst section to receive the data, and turns off the power in the section where only the main service data is transmitted. By not receiving, the power consumption of the receiving system can be reduced.

RS  Specific to frame composition and packet multiplexing Example

Next, specific embodiments of the preprocessor 230 and the packet multiplexer 240 will be described.

In an embodiment of the present invention, an N value, which is the length of one row of the RS frame configured in the RS frame encoder 302, is set to 538.

Then, the RS frame encoder 302 may receive 538 transport stream (TS) packets to configure a first RS frame having a size of 538 * 187 bytes. Then, as described above, a second RS frame having a size of 538 * 235 bytes is formed through (235,187) -RS encoding, and a third RS frame having a size of 540 * 235 bytes is formed again through a 16-bit CRC checksum generation process. do.

Meanwhile, as shown in FIG. 6A, when the number of bytes of the area A1-A5 in the area A, into which the 1 / 2-encoded mobile service data is to be inserted, is 13024 bytes (= 2428 + 2580 + 2772 + 2472). +2772 bytes). In this case, the number of bytes before 1/2 encoding is 6512 (= 13024/2) bytes.

The number of bytes in the B1 and B2 areas in the B area into which the 1 / 4-coded mobile service data is to be inserted is 2280 (= 930 + 1350) bytes. In this case, the number of bytes before 1/4 encoding is 570 (= 2280/4) bytes.

In summary, when 7082 bytes of mobile service data are input to the block processor 303, 6512 bytes of which are extended to 13024 bytes through 1/2 encoding, and 570 bytes to 2280 bytes through 1/4 encoding. To be. The group formatter 304 inserts the mobile service data extended to 13024 bytes into the areas A1 to A5 in the area A, and the mobile service data extended to 2280 bytes is inserted into the areas B1 and B2 in the B area.

In this case, the 7082 bytes of mobile service data input to the block processor 303 may be classified into an output of the RS frame encoder 302 and signaling information. According to the embodiment of the present invention, 7050 bytes of the 7082 bytes are received at the output of the RS frame encoder 302, and the remaining 32 bytes are inputted with signaling information data to perform 1/2 encoding or 1/4 encoding.

On the other hand, one RS frame that has undergone RS coding and CRC coding in the RS frame encoder 302 is composed of 540 * 235 bytes, that is, 126900 bytes. Dividing this by 7050 bytes for the time base divides it into 18 7050 bytes.

The 7050-byte mobile service data output from the RS frame encoder 302 is combined with 32-byte signaling information data and then half-coded or quarter-coded by the block processor 303 to be group-formatter 304. Is output. The group formatter 304 inserts half-coded data into the A region and inserts 1 / 4-coded data into the B region.

Next, a process of determining an N value required to form an RS frame in the RS frame encoder 302 will be described.

That is, (N + 2) * 235 bytes, which is the size of the last RS frame (that is, the third RS frame) RS-coded and CRC-coded in the RS frame encoder 302, must be allocated to an integer number of groups. At this time, since 7050 bytes are allocated to a single data group before encoding, if (N + 2) * 235 bytes are divided into 7050 (= 30 * 235), the output data of the RS frame encoder 302 is divided. It can be efficiently assigned to a data group. In an embodiment of the present invention, the value of N is determined such that N + 2 is a multiple of 30. In the present invention, 538 is determined by the N value, and N + 2 (= 540) divided by 30 gives 18. This means that mobile service data in one RS frame is divided into 18 data groups through 1/2 encoding or 1/4 encoding.

7 illustrates a process of dividing an RS frame according to the present invention. That is, an RS frame having a size of (N + 2) * 235 is divided into 30 * 235 byte blocks. Each divided block is mapped to one group. That is, data of one block having a size of 30 * 235 bytes is inserted into one data group through 1/2 encoding or 1/4 encoding.

As described above, the data group in which the corresponding data and the position holder are inserted in each layered area in the group formatter 304 is input to the packet multiplexer 240 through the data deinterleaver 305 and the packet formatter 306.

8 illustrates an operation of the packet multiplexer 240 according to a specific embodiment of the present invention. That is, the packet multiplexer 240 multiplexes a field including a data group in which mobile service data and main service data are mixed and a field containing only main service data and outputs the data to the data randomizer 251.

In this case, in order to transmit one RS frame having a size of 540 * 235 bytes, 18 data groups must be transmitted. Here, each data group includes field synchronization as shown in FIG. 6A. Therefore, 18 data groups are transmitted during 18 field periods, and the period in which the 18 data groups are transmitted is a burst on period.

In each field in the burst-on period, one data group including field synchronization and main service data are multiplexed and output. In an embodiment, each field within the burst on period is multiplexed with a data group of 118 segments and main service data of 194 segments.

Referring to FIG. 8, a field including 18 data groups is transmitted during a burst on period, that is, an 18 field period, and then a field including only main service data during a burst off period, that is, a 12 field period. Will be sent. After that, 18 fields including 18 data groups are transmitted in the burst on period, and 12 fields including only main service data are transmitted in the next burst off period.

In addition, the present invention may provide the same type of data service or may transmit different data services in the burst on period including the first 18 data groups and the burst on period including the second 18 data groups.

For example, suppose that the first burst on period and the second burst on period of FIG. 8 transmit different data services, and the receiving system wants to receive only one data service. In this case, the receiving system can reduce the power consumption of the receiving system by turning on the power only in the corresponding burst on period including the desired data service and receiving 18 fields, and turning off the power for the remaining 42 field periods. Will be. In addition, the receiving system can configure one RS frame from 18 data groups received in one burst-on period, so that decoding is easy.

In the present invention, the number of data groups included in one burst on interval depends on the size of the RS frame, and the size of the RS frame depends on the value of N. That is, the number of data groups in the burst can be adjusted by adjusting the N value. In this case, the (235,187) -RS encoding adjusts the N value in a fixed state.

In addition, the size of the mobile service data that can be inserted in the data group may vary depending on the size of trellis initialization, known data, MPEG header, RS parity, etc., inserted into the data group.

Meanwhile, since the data group including the mobile service data is multiplexed between the main service data in the packet multiplexing process, the temporal position of the main service data packet is relatively moved. The system target decoder (i.e., MPEG decoder) for main service data processing of the receiving system receives and decodes only main service data and recognizes the mobile service data packet as a null data packet.

Therefore, when the system target decoder of the receiving system receives the main service data packet multiplexed with the data group, packet jitter occurs.

In this case, since there are various buffers for the video data in the system target decoder and the size thereof is quite large, the packet jitter generated by the packet multiplexer 240 is not a big problem in the case of video data. However, the size of the buffer for audio data, which the system target decoder has, can be problematic.

That is, the packet jitter may cause overflow or underflow in a buffer for main service data of the receiving system, for example, a buffer for audio data.

Accordingly, the packet jitter reducer 220 readjusts the relative position of the main service data packet so that no overflow or underflow occurs in the buffer of the system target decoder.

The present invention describes embodiments of relocating the audio data packet of the main service data in order to minimize the influence on the operation of the audio buffer. The packet jitter reducer 220 rearranges the audio data packets in the main service data section so that the audio data packets of the main service are as uniform as possible.

The criterion for relocating the audio data packet of the main service in the packet jitter reducer 220 is as follows. In this case, it is assumed that the packet jitter reducer 220 knows the multiplexing information of the packet multiplexer 240 at a later stage.

First, if there is one audio data packet in the main service data section in the burst on section, for example, the main service data section between two data groups, the audio data packet is placed in front of the main service data section. If two are present, they are placed at the front and the rear. If there are three or more, they are placed at the front and the rear and the rest are evenly spaced between them.

Second, in the main service data section before the start of the burst on section, that is, the burst off section, the audio data packet is arranged at the last position.

Third, the audio data packet is placed first in the main service data section of the burst off section after the burst on section ends.

Packets other than audio data are arranged in a space excluding the location of audio data packets in the order of input.

On the other hand, when the position of the main service data packet is relatively readjusted as described above, the PCR value must be corrected accordingly. The PCR value is a time reference value to match the time of the MPEG decoder and is inserted into a specific area of the TS packet and transmitted. In an embodiment, the packet jitter reducer 220 performs a function of PCR value correction.

The output of the packet jitter reducer 220 is input to the packet multiplexer 240. The packet multiplexer 240 multiplexes the main service data packet output from the packet jitter reducer 220 and the mobile service data packet output from the preprocessor 230 into a burst structure according to a preset multiplexing rule. And outputs the data to the data renderer 251 of the post processor 250.

If the input data is a main service data packet, the data randomizer 251 performs rendering in the same way as the existing renderer. That is, the sync byte in the main service data packet is discarded and the remaining 187 bytes are randomly generated using pseudo random bytes generated therein, and then output to the RS encoder / unstructured RS encoder 252.

However, if the input data is a mobile service data packet, only a part of the packet may be rendered. For example, assuming that the preprocessor 230 has previously performed rendering on mobile service data, the data renderer 251 may select a sync byte of a 4-byte MPEG header included in the mobile service data packet. Discard it and perform rendering for only the remaining 3 bytes to output to the RS encoder / unstructured RS encoder 252. That is, the rest of the mobile service data except the MPEG header is output to the RS encoder / non-systematic RS encoder 252 without performing rendering. The data randomizer 251 may or may not perform the randomization of the known data (or known data location holder) and the initialization data location holder included in the mobile service data packet.

The RS encoder / unstructured RS encoder 252 adds 20 bytes of RS parity by performing RS encoding on the data to be rendered or bypassed by the data randomizer 251, and then the data interleaver 253. Will output In this case, the RS encoder / unstructured RS encoder 252 adds 20 bytes of RS parity to 187 bytes of data after performing systematic RS encoding in the same manner as the existing broadcasting system when the input data is a main service data packet. In case of a mobile service data packet, unsystematic RS coding is performed, and the 20-byte RS parity obtained at this time is inserted at a predetermined parity byte position in the packet.

The data interleaver 253 is a convolutional interleaver in bytes.

The output of the data interleaver 253 is input to a parity substituent 254 and an unstructured RS encoder 255.

On the other hand, in order to make the output data of the trellis encoder 256 located at the rear end of the parity substituter 254 into known data defined by appointment on the transmitting / receiving side, the memory in the trellis encoder 256 is first initialized. Is needed. That is, before the input known data string is trellis encoded, the memory of the trellis encoder 256 must be initialized.

At this time, the start of the known data stream is not the actual known data but the initialization data position holder inserted by the group formatter in the preprocessor 230. Therefore, a process of generating initialization data immediately before the input known data string is trellis encoded and replacing the corresponding trellis memory initialization data position holder is required.

The trellis memory initialization data is generated by determining a value thereof according to the memory state of the trellis encoder 256. In addition, a process of recalculating RS parity under the influence of the replaced initialization data and replacing the RS parity with the RS parity output from the data interleaver 253 is necessary. Since the trellis encoder 256 includes a 12-way trellis encoder, 12 bytes of initialization data for memory initialization of the trellis encoder 256 are required. In this case, when the 12 bytes are converted into 48 symbols, only the first 24 symbols are used to initialize the trellis memory, and after the trellis memory is initialized, the remaining 24 symbols may be used as known data.

Accordingly, the unstructured RS encoder 255 receives a mobile service data packet including an initialization data position holder to be replaced with initialization data from the data interleaver 253 and inputs initialization data from the trellis encoder 256. Receive. The initialization data position holder of the input mobile service data packet is replaced with the initialization data, and the RS parity data added to the mobile service data packet is removed, and then unstructured RS encoding is performed. The RS parity obtained by the unsystematic RS coding is output to the parity substituent 255. Then, the parity substituter 255 selects the output of the data interleaver 253 for data in the mobile service data packet, and selects the output of the unstructured RS encoder 255 for the RS parity. Will output

Meanwhile, when the main service data packet is input or the mobile service data packet including the initialization data location holder to be replaced is input, the parity substituter 254 selects data and RS parity output from the data interleaver 253 as it is. The trellis encoder 256 outputs the trellis encoder.

The trellis encoder 256 converts the data of the byte unit into the symbol unit, performs 12-way interleaving, trellis-encodes, and provides the symbol to the synchronous multiplexer 260 in the symbol unit.

The synchronous multiplexer 260 inserts four segment sync symbols for every 828 symbols that are trellis coded and output by the trellis encoder 256, and composes a data frame by inserting field sync segments for every 312 segments. . The data frame configured in the synchronous multiplexer 260 is output to the pilot inserter 271 of the transmitter 270.

Data in the data frame into which the pilot is inserted in the pilot inserter 271 is modulated by a modulator 272, for example, a VSB method, and then transmitted to each receiving system through the RF up converter 273. .

One data frame is composed of an odd field and an even field. At this time, each field is composed of one field sync segment and 312 data segments, and each segment is composed of 832 symbols. In the first four symbols of the field sync segment, there is a segment sync pattern, followed by PN 511, PN 63, PN 63, and PN 63, which are pseudo random sequences, and in the next 24 symbols, VSB mode. There is relevant information. Herein, the second PN 63 of the three PN 63 intervals is alternately changed in sign (or polarity) in every field. Therefore, one frame may be divided into an odd field and an even field according to the sign of the second PN 63. The remaining 104 symbols after the 24 symbols in which the VSB mode related information exists are reserved. The last 12 symbols of the previous segment are copied to the last 12 symbols of the unused region. Then, 92 symbols in the field sync segment become actual unused areas.

In the present invention, a PN sequence, that is, a known data string, may be inserted and transmitted in a part or the entirety of the unused region. In this case, the receiving system can increase the accuracy of the CIR estimation. For example, the known data sequence may use any 92 symbols in the PN127 sequence. This is an embodiment, and any known data string inserted into the field sync segment may be any pattern promised to each other in a transmission / reception system. For example, the known data pattern inserted into the field sync segment may be a symbol string having two levels.

Such known data insertion may be performed by the synchronous multiplexer 260, or may be input to the synchronous multiplexer 260 after allocating predetermined known data to a corresponding unused area when generating field synchronization.

In addition, the present invention, when inserting the known data in the unused (reserved) area of the field sync interval, in order to more accurately distinguish the even / odd field in the receiving system, the sign of the known data is alternately inserted in every field It may be. In this way, in the receiving system, in addition to the information for distinguishing even-or-field fields (for example, the sign of the second PN 63), the information for distinguishing even-or-field fields inserted in the unused area (for example, By separating the even / or odd field using the sign of data), it is possible to further improve the accuracy of distinguishing the even and odd fields.

Block handler

9 is a detailed block diagram of a block processor according to an embodiment of the present invention, which may include a byte-bit converter 401, a symbol encoder 402, a symbol interleaver 403, and a symbol-byte converter 404. Can be.

The byte-bit converter 401 divides the mobile service data byte input from the RS frame encoder 112 into bits and outputs the bits to the symbol encoder 402.

The byte-symbol converter 401 may also receive signaling information including a transmission parameter and the like, and the signaling information bytes are also divided into bits and output to the symbol encoder 402. In this case, the signaling information including the transmission parameter may be input to the block processor 303 via the data renderer 301 and the RS frame encoder 302 in the same manner as the mobile service data processing process, or the data renderer ( It may be input directly to the block processor 303 without passing through the 301 and the RS frame encoder 302.

The symbol encoder 402 is a G / H encoder that encodes and outputs the input data G bits into H bits.

In one embodiment of the present invention, the symbol encoder 402 may be encoded at a half code rate (or sometimes referred to as half encoding) or at a quarter code rate (also referred to as quarter encoding). Suppose we do The symbol encoder 402 performs 1/2 encoding or 1/4 encoding on the received mobile service data and signaling information. The signaling information is also regarded as mobile service data and processed.

The symbol encoder 402 receives 1 bit in the case of 1/2 encoding, encodes it into 2 bits (that is, one symbol), and outputs it. Two symbols).

FIG. 10 is a detailed block diagram showing an embodiment of the symbol encoder 402, which is composed of two delayers 501 and 503 and three adders 502, 504 and 505. output to u3). At this time, the data bit U is output as it is as the most significant bit u0 and encoded and output as the lower bit u1u2u3.

That is, the input data bits U are output as they are as most significant bits u0 and output to the first and third adders 502 and 505. The first adder 502 adds the input data bit U and the output of the first delayer 501 to output to the second delayer 503, and for a predetermined time (for example, in the second delayer 502). The delayed data is output to the lower bit u1 and fed back to the first delay unit 501. The first delayer 501 delays the data fed back from the second delayer 502 by a predetermined time (for example, one clock) and outputs the delayed data to the first adder 502 and the second adder 504. . The second adder 504 adds the outputs of the first and second delayers 501 and 503 to output the lower bit u2. The third adder 505 adds the input data bit U and the output of the second adder 504 to output the lower bit u3.

In this case, if the input data bit U is data to be encoded at a 1/2 code rate, the symbol encoder 402 may configure and output one symbol of u0u1 bits among the four output bits u0u1u2u3. In addition, for data to be encoded at a 1/4 code rate, a symbol consisting of u0u1 bits may be output, followed by another symbol consisting of u2u3 bits. In another embodiment, if the data is to be encoded at a 1/4 code rate, a symbol composed of u0u1 bits may be repeatedly output.

In another embodiment, the symbol encoder 402 outputs all four output bits u0u1u2u3, and when the symbol interleaver 403 at the next stage has a 1/2 code rate, only a symbol consisting of u0u1 bits among the four output bits u0u1u2u3 is used. If the code rate is 1/4, the symbol may be designed to select both a symbol composed of u0u1 bits and another symbol composed of u2u3 bits. In another embodiment, when the code rate is 1/4, a symbol composed of u0u1 bits may be repeatedly selected.

The output of the symbol encoder 402 is input to the symbol interleaver 403, and the symbol interleaver 403 performs block interleaving on a symbol unit basis for the output data of the symbol encoder 402.

The symbol interleaver 403 may be applied to any interleaver as long as it is an interleaver structurally performing any order rearrangement. However, according to an embodiment of the present invention, a variable length symbol interleaver applicable even when the length of symbols to be rearranged is varied will be described as an embodiment.

FIG. 11 is a diagram illustrating an embodiment of a symbol interleaver according to the present invention, and is a variable length symbol interleaver applicable even when a length of symbols to be rearranged is varied.

In particular, FIG. 11 shows an example of a symbol interleaver when K = 6 and L = 8. K is the number of symbols output for symbol interleaving in the symbol encoder 402, and L is the number of symbols actually interleaved in the symbol interleaver 403.

The symbol interleaver 403 of the present invention must satisfy the condition L ≥ K while L = 2 ⁿ (where n is a natural number). If the values of K and L are different, an interleaving pattern is created by adding null or dummy symbols by the number of differences (= LK).

Therefore, K is a block size of actual symbols input to the symbol interleaver 403 for interleaving, and L is an interleaving unit in which interleaving is performed by an interleaving pattern generated by the symbol interleaver 403.

FIG. 11 shows an example, and the number of symbols (= K) output from the symbol encoder 402 for interleaving is 6 symbols, and the actual interleaving unit L is 8 symbols. Therefore, as shown in FIG. 11A, two symbols are added as null symbols to form an interleaving pattern.

Equation 2 below receives the K symbols to be rearranged in sequence in the symbol interleaver 403 in order, finds L = 2 ⁿ and satisfies the condition L ≥ K and creates an interleaving pattern and rearranges them. Is a mathematical expression of the process.

For all positions 0 ≤ i ≤ L-1,

P (i) = {S x i x (i + 1) / 2} mod L

Where L ≧ K and L = 2 ⁿ , where n and S are natural numbers. In FIG. 11, S is 89 and L is 8.

After rearranging the order of the K input symbols and the (LK) null symbols in units of L symbols as shown in Equation 2 and FIG. 11 (b), the null symbols are shown in Equation 3 below and FIG. 11 (c). The interleaved symbols are output to the symbol-byte converter 404 in the sorted order.

if P (i)> K-1, then P (i) position removed and aligned

The symbol-byte converter 404 converts the mobile service data symbols outputted after the sequence rearrangement is completed in the symbol interleaver 403 into bytes and outputs them to the group formatter 304.

12A is a detailed block diagram of a block processor according to another embodiment of the present invention, and may include an interleaving nit 610 and a block formatter 620.

The interleaving unit 610 may include a byte-symbol converter 611, a symbol-byte converter 612, a symbol interleaver 613, and a symbol-byte converter 614. The symbol interleaver is also called a block interleaver.

Bytes of the interleaving unit 610 The symbol converter 611 converts the mobile service data X output in the unit of byte from the RS frame encoder 302 in the unit of symbol and outputs it to the symbol-byte converter 612 and the symbol interleaver 613. That is, the byte- The symbol converter 611 outputs two bits of the input mobile service data byte (= 8 bits) as one symbol. This is because the input of the trellis encoder 256 is a symbol unit of 2 bits. The relationship between the block processor 303 and the trellis encoder 256 will be described later.

In this case, the byte-symbol converter 611 may also receive signaling information including a transmission parameter and the like. The signaling information bytes may also be divided in symbol units so that the symbol-byte converter 612 and the symbol interleaver 613 are received. )

The symbol-byte converter 612 collects four symbols output from the byte-symbol converter 611 to form a byte, and outputs the byte to the block formatter 620. In this case, since the symbol-byte converter 612 and the byte-symbol converter 611 are inverse processes, the results of the two blocks are canceled so that the input data X is bypassed to the block formatter 620 as shown in FIG. 12B. It is effective. That is, since the interleaving unit 610 of FIG. 12B has an equivalent structure to that of the interleaving unit 610 of FIG. 12A, the same reference numerals are used.

The symbol interleaver 613 performs block interleaving on a symbol-by-symbol basis for the data output from the byte-symbol converter 611 and outputs the result to the symbol-byte converter 614.

The symbol interleaver 613 may be applied to any interleaver as long as the interleaver is structurally rearranged. According to an embodiment of the present invention, a variable length interleaver may be used even when the length of a symbol to be rearranged is various. For example, the symbol interleaver of FIG. 11 may also be applied to FIGS. 12A and 12B.

The symbol-byte converter 614 collects the mobile service data symbols outputted after the sequence rearrangement is completed in the symbol interleaver 613, forms a byte, and outputs the byte to the block formatter 620. That is, the symbol-byte converter 614 forms four bytes by collecting four symbols output from the symbol interleaver 613.

The block formatter 620 arranges outputs of the symbol-byte converters 612 and 614 according to a predetermined criterion in the block as shown in FIG. In this case, the block formatter 620 operates in relation to the trellis encoder 256.

That is, the block formatter 620 determines the position (or order) of the remaining data except for mobile service data such as main service data, known data, RS parity data, and MPEG header data input to the trellis encoder 256. Consider the mobile service data output order of each symbol-byte converter 612,614.

The trellis encoder 256 has twelve trellis encoders as an example.

14 is a detailed block diagram of a trellis encoder 256 according to an embodiment of the present invention, in which 12 identical trellis encoders are combined into an interleaver for noise dispersion. Each trellis encoder may include a pre coder.

FIG. 15A illustrates a state in which the block processor 303 and the trellis encoder 256 are concatenated. In practice, in the transmission system, as shown in FIG. 3, a plurality of blocks exist between the preprocessor 230 including the block processor 303 and the trellis encoder 256, but in the receiving system, the two blocks are considered to be concatenated. Decoding will be performed.

However, the data except for mobile service data such as main service data, known data, RS parity data, and MPEG header data inputted to the trellis encoder 256 are the block processor 303 and the trellis encoder 256. Data added in blocks existing in between. 15B illustrates an example in which the data processor 650 is disposed between the block processor 303 and the trellis encoder 256 in consideration of such a situation.

Here, when the interleaving unit 610 of the block processor 303 performs encoding at a 1/2 code rate, the interleaving unit 610 may be configured as shown in FIG. 12A (or FIG. 12B). 3, the data processor 650 includes a group formatter 304, a data deinterleaver 305, a packet formatter 306, a packet multiplexer 240, and a data randomizer of the post processor 250. 251, an RS encoder / unstructured RS encoder 252, a data interleaver 253, a parity substituent 254, and an unstructured RS encoder 255.

At this time, the trellis encoder 256 symbolizes the input data and sends the trellis encoder to each trellis encoder according to a predefined method. At this time, one byte is converted into four symbols consisting of two bits, and symbols made from one byte are all transmitted to the same trellis encoder. Then, each trellis encoder precodes the upper bits of the input symbols and outputs them to the highest output bit C2, and outputs the lower bits to two output bits C1 and C0 by trellis coding.

The block formatter 620 controls the output bytes of each symbol-byte converter to be transmitted to different trellis encoders.

Next, detailed operations of the block formatter 620 will be described with reference to FIGS. 9 through 12.

12A, the output byte of the symbol-byte converter 612 and the output byte of the symbol-byte converter 614 are different from each other of the trellis encoder 256 under the control of the block formatter 620. It is input to the trellis encoder.

In the present invention, for convenience of explanation, the output byte of the symbol-byte converter 612 is referred to as X, and the output byte of the symbol-byte converter 614 is referred to as Y. In FIG. 13A, each number 0 to 11 indicates a trellis encoder of the first to twelfth bits of the trellis encoder 256.

The block formatter 620 inputs output bytes of the symbol-byte converter 612 to trellis encoders 0 to 5 of the trellis encoder 256. In one embodiment, the output order of each symbol-byte converter 612, 614 is arranged such that the output bytes of the symbol-byte converter 614 are inputted to the trellis encoders 6-11 of numbers 6-11. do. Here, the trellis encoders to which the output bytes of the symbol-byte converter 612 are allocated and the trellis encoders to which the output bytes of the symbol-byte converter 614 are assigned are one embodiment for understanding the present invention. It is only.

In addition, assuming that the input of the block processor 303 is a block composed of 12 bytes, the symbol-byte converter 612 outputs 12 bytes from X0 to X11, and the symbol-byte converter 614 also outputs Y0 to According to an embodiment, 12 bytes are output to Y11.

FIG. 13B illustrates an embodiment of data input to the trellis encoder 256, in which main service data and RS parity data as well as mobile service data are input to the trellis encoder 256. The example is distributed to each trellis encoder. That is, while the mobile service data output from the block processor 303 passes through the group formatter 304, the mobile service data is output in a form in which main service data and RS parity data are mixed with the mobile service data as shown in FIG. Each byte is input to 12 trellis encoders according to their position in the data group after data interleaving.

If the output bytes (X, Y) of the symbol-byte converter 612, 614 are allocated to the corresponding trellis encoder according to the aforementioned principle, the input of each trellis encoder is as shown in FIG. 13 (b). It can be in form.

That is, referring to FIG. 13B, six mobile service data bytes X0 to X5 output from the symbol-byte converter 612 are the first to sixth tracks of the trellis encoder 256. The two mobile service data bytes (Y0, Y1) sequentially allocated (or distributed) to the release encoders 0 to 5 and output from the symbol-byte converter 614 are the seventh and eighth trellis encoders. Sequentially assigned to (6,7). Four main service data bytes of the five main service data bytes are sequentially allocated to the ninth to twelfth trellis encoders 8 to 11, and the next one main service data byte is again the first trellis encoder. An example is assigned to (0).

Suppose that mobile service data, main service data, RS parity data, etc. are allocated to each trellis encoder as shown in FIG. 13 (b). As described above, the input of the block processor 303 is a block composed of 12 bytes. The symbol-byte converter 612 outputs 12 bytes from X0 to X11, and the symbol-byte converter 614 also outputs Y0. Suppose that 12 bytes are output until ~ Y11. In this case, the block formatter 620 outputs the symbol-byte converters 612 and 614 in the order X0 to X5, Y0, Y1, X6 to X10, Y2 to Y7, X11, Y8 to Y11 as shown in FIG. Outputs an array.

That is, it is determined in which trellis coder each data byte is encoded according to which position in the data frame. In this case, not only the mobile service data but also main service data, MPEG header data, and RS parity data are input to the trellis encoder 256, so that the block formatter 620 performs a data group format after data interleaving. Suppose you know information about.

FIG. 16 is a block diagram showing an embodiment of a block processor for encoding at a 1 / N code rate according to the present invention, and includes (N-1) symbol interleavers 741 to 74N-1 configured in parallel. do. That is, a block processor having a 1 / N code rate has a total of N branches, including branches or paths in which original input data is passed to the block formatter 730 as it is. Each of the symbol interleavers 741 to 74N-1 may be configured with different symbol interleavers. Corresponding (N-1) symbol-byte converters 751 to 75N-1 may be configured at the output terminals of the (N-1) symbol interleavers 741 to 74N-1. Outputs of the (N-1) symbol-byte converters 751 to 75N-1 are also input to the block formatter 730.

In the present invention, N is one embodiment less than or equal to 12.

If N is 12, the block formatter 730 may arrange the output data such that the output byte of the twelfth symbol-byte converter 75N-1 is input to the twelfth trellis encoder. If N is 3, the block formatter 730 inputs the output bytes of the symbol-byte converter 720 to the first to fourth trellis encoders of the trellis encoder 256, and the symbol-byte converter ( The output bytes of 751) may be input to the fifth to eighth trellis encoders, and the output bytes of the symbol-byte converter 752 may be input to the ninth to twelfth trellis encoders.

At this time, the output data order of each symbol-byte converter may vary depending on the location in the data group of data other than the mobile service data mixed with the mobile service data output from each symbol-byte converter.

17 shows a detailed block diagram of a block processor in another embodiment of the present invention, in which a block formatter is removed and a role of the block formatter is performed in a group formatter. That is, the block processor of FIG. 17 may include a byte-symbol converter 810, a symbol-byte converter 820, 840, and a symbol interleaver 830. In this case, the output of each symbol-byte converter 820, 840 is input to the group formatter 850.

In addition, the block processor may add a symbol interleaver and a symbol-byte converter to obtain a desired code rate. If encoding is desired at 1 / N code rate, the original input data is composed of N branches and N-1 branches in parallel, including branches or paths that are passed to the group formatter 850 as it is. N-1) symbol interleavers and symbol-byte converters may be provided. At this time, the group formatter 850 inserts a position holder for securing the position for the MPEG header, the unstructured RS parity, and the main service data, and places the bytes output from each branch of the block processor at a predetermined position.

The number of trellis encoders, the number of symbol-byte converters, and the number of symbol interleavers presented in the present invention are preferred embodiments or simple examples, and thus the scope of the present invention is not limited to the above numerical values. In addition, it is apparent to those skilled in the art that the byte type and position allocated to each trellis encoder of the trellis encoder 256 may vary according to the data group format. will be. Therefore, it is to be understood that the present invention is not limited to the above described embodiments.

As described above, the mobile service data encoded and output at the 1 / N code rate by the block processor 303 is input to the group formatter 304. In this embodiment, the output data order in the block formatter of the block processor 303 is arranged and output according to the byte position in the data group.

Signaling  Information processing

In the transmitter 200 according to the present invention, transmission parameters may be inserted in various methods and positions and transmitted to the receiving system.

 To facilitate understanding of the present invention, transmission parameters to be transmitted from a transmitter to a reception system will be defined. The transmission parameter includes data group information, area information in the data group, the number of RS frames constituting a super frame (Super frame size: SFS), the number of RS parities (P) per column in the RS frame, and the row direction of the RS frame. Use of checksum added to determine whether there is an error, type and size (if present, add 2 bytes as CRC) if used, number of data groups constituting one RS frame-RS frame is one burst period Is equal to the number of data groups (Burst size (BS)) in a burst-and so on, and there are a turbo code mode and an RS code mode. In addition, the transmission parameters required for burst reception are Burst Period (BP)-one burst period is a count of the number of fields from the start of one burst to the start of the next burst. The order occupied in one super frame (Permuted Frame Index (PFI)), the order in which a group is currently transmitted in one RS frame (burst) (Group Index (GI), burst size, etc.). According to the burst operation method, there is the number of fields remaining until the start of the next burst (TNB), and by transmitting this information as a transmission parameter, the relative until the start of the next burst for each data group transmitted to the receiving system. You can also tell the distance (number of fields).

The information included in the transmission parameter is only one embodiment for better understanding of the present invention, and the present invention is not limited to the above embodiment because addition and deletion of information included in the transmission parameter can be easily changed by those skilled in the art. Will not.

As a first embodiment, the transmission parameter may allocate and insert a certain area of the mobile service data packet or data group. In this case, in the receiving system, once synchronization and equalization of the received signal are performed and symbol-based decoding is performed, the packet deformatter can separate and detect the mobile service data and the transmission parameter. In the case of the first embodiment, the transmission parameter may be inserted and transmitted in the group formatter 304.

As a second embodiment, a transmission parameter may be inserted by multiplexing with other data. For example, when multiplexing the known data with the mobile service data, the transmission parameter may be inserted instead of the known data at a position where the known data may be inserted, or may be mixed with the known data. In the case of the second embodiment, the transmission parameter may be inserted and transmitted in the group formatter 304 or the packet formatter 306.

As a third embodiment, the transport parameter may be inserted and transmitted at a higher layer than a transport stream packet. In this case, the receiving system should be able to receive the signal and make it beyond the TS packet layer, and the purpose of the transmission parameter is to verify the transmission parameter of the currently received signal and to give the transmission parameter of the signal to be received later. Can be performed.

In the present invention, various transmission parameters related to a transmission signal are inserted and transmitted through the method of the above-described embodiments, wherein the transmission parameters may be inserted and transmitted only through one embodiment or may be inserted through some embodiments. It may be transmitted or may be inserted and transmitted through all embodiments. In addition, the information in the transmission parameter may be inserted in duplicate in each embodiment, or only necessary information may be inserted and transmitted in the corresponding position of the embodiment.

In addition, the transmission parameter may be inserted into a corresponding region after performing block coding of a short period to ensure robustness. Examples of the short-term block coding method include Kerdock coding, BCH coding, RS coding, repetitive coding of transmission parameters, and the like. In addition, a combination of several block encodings is also possible.

The transmission parameters may be collected to form a small block code and inserted into a byte allocated for signaling in a data group for transmission. However, in this case, since the transmission parameter value is obtained by passing through the block decoder in terms of reception, transmission parameters such as the turbo code mode and the RS code mode necessary for block decoding must be obtained first. For this reason, the transmission parameter related to the mode may insert the transmission parameter into a part of the known data region, and in this case, symbol correlation may be used for fast decoding.

On the other hand, when the transmission parameter is inserted into the known data area and transmitted, since the reliability of the transmission parameter passes through the transmission channel, the reliability thereof may be lowered. Therefore, one of the predefined patterns may be inserted according to the transmission parameter. In this case, the reception system may recognize a transmission parameter by performing a correlation operation between the received signal and predefined patterns.

For example, suppose that the number of groups in the burst is 5, which is determined in advance by an appointment of the transmitting / receiving side in a K pattern. Then, when the number of groups in the burst is five, the transmitter inserts and transmits a K pattern. The receiving side performs a correlation operation between the received data and various reference patterns including the pre-generated K pattern. At this time, if the correlation value between the received data and the K pattern is the largest, the received data indicates a transmission parameter, in particular, the number of groups in the burst, and the number is recognized as five.

Next, a process of inserting and transmitting a transmission parameter will be described by dividing the first and second embodiments.

First Example

18 is a schematic diagram of the present invention for receiving a transmission parameter from the group formatter 304 and inserting the transmission parameter into the A region in the data group.

In this case, the group formatter 304 receives mobile service data from the block processor 303. In contrast, the transmission parameter may be input to the group formatter 304 after at least one of data rendering, RS frame encoding, and block processing, or input to the group formatter 304 without going through all three processes. May be In addition, the transmission parameter may be provided by the service multiplexer 100 or may be generated and provided within the transmitter 200.

The transmission parameter may include information necessary for receiving and processing data included in the data group in a receiving system. For example, the transmission parameter may include data group information, multiplexing information, and the like.

The group formatter 304 inserts mobile service data and transmission parameters input to a corresponding area in the data group according to a rule for forming a data group.

According to an embodiment, the transmission parameter may be inserted in an area A of the data group after a short period of block encoding. In particular, the transmission parameter may be inserted at any position promised in the A area.

 If it is assumed that the transmission parameter has been processed by the block processor 303, the block processor 303 may also encode 1/2 or 1 / signaling information including the transmission parameter in the same manner as the mobile service data processing. 4 is encoded and then output to the group formatter 304. The signaling information is also regarded as mobile service data and processed.

FIG. 19 is a block diagram illustrating an example of a block processor that receives a transmission parameter and processes the same as mobile service data, and further includes a signaling information provider 411 and a multiplexer 412 to the component of FIG. 9. An example is shown.

That is, the signaling information provider 411 outputs the signaling information including the transmission parameter to the multiplexer 412. The multiplexer 412 multiplexes the signaling information and the output of the RS frame encoder 302 and outputs them to the byte-bit converter 401.

The byte-bit converter 401 divides the mobile service data byte or signaling information byte output from the multiplexer 412 into bits and outputs the result to the symbol encoder 402.

Since the subsequent operation may refer to FIG. 9 described above, a detailed description thereof will be omitted.

If the detailed configuration of the block processor 303 applies at least one of FIGS. 12 and 15 to 17, the signaling information providing unit 411 and the multiplexer 412 may be provided in front of the bind-symbol converter. have.

In addition, if the transmission parameter provided from the signaling information providing unit 411 is a symbol unit, the signaling information providing unit 411 and the multiplexer 412 may be provided after the byte-symbol converter.

2nd Example

On the other hand, when the group formatter 304 inserts the known data generated by a predetermined method into a corresponding region in the data group, a transmission parameter may be inserted in place of the known data in at least a portion of the region where the known data can be inserted. .

For example, if a long known data string is inserted at the beginning of the A region in a data group, some of these may insert transmission parameters instead of known data. At this time, some of the known data strings inserted in the remaining region except for the region in which the transmission parameter is inserted may be used to capture the starting point of the data group in the receiving system, and others may be used for channel equalization in the receiving system.

When the transmission parameter is inserted in the known data area instead of the known data, the transmission parameter may be inserted by block coding in a short period or a predetermined pattern may be inserted according to the transmission parameter as described above.

If the group formatter 304 inserts the known data position holder instead of the known data into an area in which the known data in the data group can be inserted, the transmission parameter may be inserted in the packet formatter 306.

That is, the packet formatter 306 may insert and replace the known data in the known data position holder when the known data position holder is inserted in the group formatter 304 or insert the known data in the group formatter 304. If inserted, it can be output as is.

FIG. 20 is a block diagram illustrating an example in which the packet formatter is extended to insert a transmission parameter in the packet formatter 306. The known data generator 351 and the signaling multiplexer 352 may be arranged in the packet formatter 306. FIG. ) Is further included. The transmission parameter input to the signaling multiplexer 352 includes information on the length of the current burst, information indicating the time of the next burst, the location and length of the groups in the burst, the current group to the next group in the burst. It may include time, information about known data, and the like.

The signaling multiplexer 352 selects one of a transmission parameter and known data generated from the known data generator 351 and outputs it to the packet formatter 306. The packet formatter 306 inserts and outputs known data or transmission parameters output from the signaling multiplexer 352 into a known data position holder output from the data deinterleaver 305. That is, the packet formatter 306 inserts and outputs transmission parameters instead of known data in at least a portion of the known data area.

For example, when the known data position holder is inserted at the beginning of the area A in the data group, a transmission parameter may be inserted in some of the known data position holders instead of the known data.

When the transmission parameter is inserted in the known data position holder instead of the known data, the transmission parameter may be inserted by block encoding in a short period or a predetermined pattern may be inserted according to the transmission parameter.

That is, the signaling multiplexer 352 multiplexes the known data and the transmission parameters (or patterns defined according to the transmission parameters) to form a new known data string and outputs the new known data string to the packet formatter 306. The packet formatter 306 removes the main service data location holder, the RS parity location holder from the output of the data deinterleaver 305, and sends 188 bytes of mobile to the output of the mobile service data, the MPEG header, and the signaling multiplexer 352. The service data packet is generated and output to the packet multiplexer 240.

In this case, the A region in each data group has a different known data pattern. Therefore, the reception system recognizes only the symbol of the promised interval in the known data sequence as a transmission parameter.

In this case, since the known data may be inserted at another location such as the packet formatter 306, the group formatter 304, or the block processor 303 according to the design method of the transmission system, the known data is transmitted instead of the known data in the block in which the known data is inserted. You can insert a parameter.

In the second embodiment, a transmission parameter including a processing method of the block processor 303 may be inserted into a part of the known data area and transmitted. In this case, a symbol processing method and its position for the transmission parameter symbol itself are determined and should be located so as to transmit and receive in time before other data symbols to be decoded. Then, the transmission parameter symbol may be detected before data symbol decoding by the receiving system and used for decoding for the data symbol.

Receiving system

21 is a block diagram showing an embodiment of a digital broadcast receiving system according to the present invention. In the digital broadcasting reception system of FIG. 21, the reception performance may be improved by performing carrier synchronization recovery, frame synchronization recovery, channel equalization, and the like using known data information inserted and transmitted in a mobile service data section by a transmission system.

The reception system according to the present invention for this purpose is a tuner 901, a demodulator 902, an equalizer 903, a known data detector 904, a block decoder 905, a data formatter 906, an RS frame decoder 907 ), And a data derandomizer 908. The receiving system may further include a data deinterleaver 909, an RS decoder 910, and a data derandomizer 911. For convenience of description, the data deformatter 906, the RS frame decoder 907, and the data derandomizer 908 are referred to as mobile service data processing units, and the data deinterleaver 909, the RS decoder 910, and data. The derandomizer 911 will be referred to as a main service data processing unit.

That is, the tuner 901 tunes the frequency of a specific channel, down-converts the intermediate frequency (IF) signal, and outputs the demodulator 902 and the known data detector 904.

The demodulator 902 performs automatic gain control, carrier recovery, and timing recovery on the input IF signal to generate a baseband signal and outputs the same to the equalizer 903 and the known data detector 904.

The equalizer 903 compensates for the distortion on the channel included in the demodulated signal and outputs it to the block decoder 905.

At this time, the known data detector 904 detects the known data position inserted by the transmitting side from the input / output data of the demodulator 902, that is, data before demodulation or data after demodulation is performed, and the detected known data. The known data generated at the position together with the known data position information is output to the demodulator 902 and the equalizer 903.

 In addition, the known data detector 904 is the block decoder 905 information for distinguishing the mobile service data with additional encoding and the main service data without additional encoding at the transmitting side by the block decoder 905. You can also output Although the connection state is not illustrated in the diagram of FIG. 21, the information detected by the known data detector 904 may be generally used in the reception system, and may be used in the data deformatter 906 and the RS frame decoder 907. have.

The demodulator 902 can improve demodulation performance by using the known data position information and known data at the time of timing restoration or carrier recovery, and the equalizer 903 uses the known data position information and known data as well. It is possible to improve the equalization performance. In addition, the equalization performance may be improved by feeding back the decoding result of the block decoder 905 to the equalizer 903.

In this case, the transmitting side may periodically insert and transmit known data into the data frame as shown in FIG. 6A.

FIG. 22 shows a part of the A area in the data group in the data frame having the data structure as shown in FIG. 6A. In particular, FIG. 22 is an enlarged view from the field sync segment to the third known data area. The data frame of FIG. 22 represents data inserted and transmitted in each area in symbol units. Here, one byte consists of four symbols and one symbol consists of two bits.

In the data frame shown in FIG. 23, the field sync segment consists of 832 symbols. Some of the 832 symbols may include a known data string.

Each known data area includes an initialization data area (ie, a red area) for transmitting trellis memory initialization data. For example, 48 symbols may be allocated to the initialization data area. In this case, the initialization data required to initialize one trellis encoder among the 12 trellis encoders is 2 symbols. Therefore, 24 symbols are needed to initialize the 12 trellis encoders. Therefore, the remaining 24 symbols in the initialization data area of each known data area can be used as known data.

At least one of the first to fifth known data areas (eg, the first known data area) includes a first known data pattern, and the first to fifth known data areas each include a second known data pattern. Include.

The second known data pattern may be included immediately after the trellis memory initialization data in the corresponding known data area, or may be included after another pattern of known data sequences. This is because the start positions of the first to fifth known data areas and the lengths of the first to fifth known data areas are different, so that the second known data pattern is maintained at a constant interval.

The first known data area located approximately 16 segments after the field sync segment includes a trellis memory initialization data area (red area), a third known data pattern area (blue hatched area), and a second known data pattern area ( CIR TS area), a fourth known data pattern area (reserved TS area), a first known data pattern area (ACQ TS area), and a fifth known data pattern area (black area).

The trellis memory initialization data area (red area) is, for example, an area in which 24 symbols are allocated and the trellis memory initialization is performed at the transmitting side. The third known data pattern region (blue shaded region) is a region which is preliminarily allocated so that the second known data pattern maintains the same interval as the second known data pattern of the other known data region. The third known data pattern included in the data pattern region may be used in the receiving system or may be preliminarily placed.

For example, 1424 symbols are allocated to the second known data pattern region (CIR TS region), and a second known data pattern that can be used for channel equalization is inserted. The starting position in the segment of the second known data pattern area is the same in all known data areas.

For example, 252 symbols are allocated to the fourth known data pattern region (reserved TS region). According to the embodiment of the present invention, the transmission parameter is inserted into the fourth known data pattern region and transmitted. For example, mode information indicating a code rate of each region in the data group may be inserted. For convenience of explanation, a mode indicating the code rate of each region will be referred to as a serial concatenated convolution code (SCCC) mode. Table 1 below shows an example of the SCCC mode.

For example, if the SCCC mode value extracted from the fourth known data pattern region is 3, the A and C regions in the data group are encoded at 1/2 code rate, and the B region is encoded at 1/4 code rate. Indicates that the In the transmitting side of the present invention, six patterns corresponding to the respective mode values in Table 1 may be generated by an appointment of the transmitting / receiving side, and the corresponding patterns may be inserted into the fourth known data pattern area for each data group.

In this case, the SCCC mode information can be obtained from the fourth known data pattern region before the block decoder 905 of the receiving system performs decoding according to the SCCC mode.

In the meantime, a plurality of first known data patterns are inserted in the first known data pattern area (ACQ TS area) in order to obtain initial carrier frequency synchronization. For example, one first known data pattern is allocated to 576 symbols. Therefore, in Fig. 22, the first known data pattern of 576 symbols is inserted continuously in the first known data pattern area.

A fifth known data pattern region (black region) is positioned next to the first known data pattern region among the first known data regions, and the fifth known data pattern included in the fifth known data pattern region is received by the receiving system. It may be used or may be left as a spare.

On the other hand, the second known data area located about 16 segments after the first known data area includes a trellis memory initialization data area (red area), a third known data pattern area (blue hatched area), and a second A known data pattern region (CIR TS region).

In the trellis memory initialization data area (red area) of the second known data area, 24 symbols are allocated, for example, and data used for trellis memory initialization is inserted. The third known data pattern region (blue shaded region) is a region which is preliminarily allocated so that the second known data pattern maintains the same interval as the second known data pattern of the other known data region. The third known data pattern included in the data pattern region may be used in the receiving system or may be preliminarily placed.

For example, 1424 symbols are allocated to the second known data pattern region (CIR TS region), and a second known data pattern that can be used for channel equalization is inserted. The starting position in the segment of the second known data pattern area is the same in all known data areas.

The third known data area located about 16 segments after the second known data area includes a trellis memory initialization data area (red area) and a second known data pattern area (CIR TS area) used for channel equalization. Include.

The initialization data area (red area) in the third known data area includes 12 bytes, in which only two symbols are used to initialize the trellis memory for each byte. Therefore, the remaining two symbols in each byte, that is, the remaining 24 symbols of the initialization data region, can be used for channel equalization.

In this data structure, there are 11892 symbols of general data between the field sync area and the first known data area, 10480 symbols of general data between the first known data area and the second known data area, and the second known data area and the third known data area. 11888 symbols of general data may be inserted and transmitted between the known data areas. The general data corresponds to the remaining data except for the field sync and the known data area, for example, main service data, mobile service data, RS parity data, MPEG header data, and the like.

23 is a flowchart showing an embodiment of a known data position detection method according to the present invention. The known data detector 904 first detects the position of the first known data area using a plurality of first known data patterns of the first known data area (step 921).

In this case, since the known data detector 904 knows the structure of the data frame, when the location of the first known data area is detected, the symbol is known based on the location of the first known data area. It is possible to estimate the field synchronizing position in the data group that is temporally ahead of the data area (step 922). In addition, a symbol or segment may be counted based on the location of the first known data area to estimate positions of second to fifth known data areas within the corresponding data group located later in time than the first known data area (step 923). .

The estimated field sync position and known data position information are provided to the demodulator 902 and the channel equalizer 903. For example, the field sync position and position information of the second known data pattern region to which 1424 symbols in each known data region are allocated may be provided to the channel equalizer 903. In this case, the channel equalizer 903 has a field synchronization data and a second known data pattern region inserted in a field synchronization region for the estimation of a channel impulse response in the field synchronization period and a known data interval into which the second known data pattern is inserted. Assume that the second known data pattern inserted into the terminal is stored in advance.

In addition, the known data detector 904 may estimate an initial frequency offset from the first known data pattern in the process of detecting the first known data region position. In this case, the demodulator 902 may more accurately estimate and compensate carrier frequency offset from the known data position information and the initial frequency offset estimate.

24 is a block diagram illustrating an example for estimating a known data position and an initial frequency offset in a known data detector according to the present invention.

FIG. 24 illustrates a case in which an input signal is oversampled by N times. In other words, N represents a sampling rate of the received signal.

Referring to FIG. 24, the known data detection and initial frequency offset estimator include N partial correlation units 1011 to 101N configured in parallel, a known data position detection and frequency offset determiner 1020, a known data extractor 1030, and a buffer. 1040, multiplier 1050, NCO 1060, frequency offset estimator 1070, and adder 1080.

The first partial correlator 1011 consists of a 1 / N decimator and a partial correlator.

The second partial correlator 1012 consists of a one sample delay, a 1 / N decimator, and a partial correlator.

The Nth partial correlator 101N is composed of an N-1 sample delay unit, a 1 / N decimator, and a partial correlator.

This is to match the phase of each sample in the oversampled symbol with the phase of the original symbol, decimate the samples in the remaining phases, and then perform partial correlation respectively. That is, the input signal is decimated at a ratio of 1 / N for each sampling phase and passes through each partial correlator.

For example, if the input signal is oversampled twice, that is, N = 2, this means that two symbols are included in one symbol. In this case, two partial correlation units (for example, 1011 and 1012) Required, 1 / N decimator is 1/2 decimator.

At this time, the 1 / N decimator of the first partial correlator 1011 decimates (removes) a sample between the symbol position and the symbol position among the input samples and outputs the partial correlator.

The 1-sample delay of the second partial correlation unit 1012 delays the input sample by 1 sample and outputs the 1 / N decimator. Subsequently, the 1 / N decimator decimates (removes) a sample between the symbol position and the symbol position among the samples input from the 1 sample delay unit and outputs the partial correlator.

Each of the partial correlators outputs a correlation value and an approximate frequency offset estimation value at a predetermined period of the VSB symbol to the known data position detection and frequency offset determination unit 1020.

The known data position detection and frequency offset determiner 1020 stores the output of the partial correlator for each sampling phase for a data group period or a predetermined period, and determines a position where the correlation value is maximum among the values as the reception position of the known data. The frequency offset estimation value of the instant is finally determined as an approximate frequency offset value of the receiving system.

The known data position information is position information of a first known data region into which a first known data pattern is inserted. From this known data position information, the field synchronizing position and the positions of the second to fifth known data regions can be estimated. In addition, the position of the second known data pattern region allocated with 1424 symbols in each known data region may be estimated.

The known sequence position indicator is provided to the known data extractor 1030, the demodulator 902, and the equalizer 903, and an approximate frequency offset is provided to the adder 1080 and the NCO 1060. do.

Meanwhile, the buffer 1040 temporarily stores the received data and outputs the received data to the known data extractor 1030 while the N partial correlation units 1011 to 101N estimate the known data position detection and the approximate frequency offset.

The known data extractor 1030 extracts the known data from the output of the buffer 1040 by using the known data position information output from the known data position detection and frequency offset determiner 1020 and then multiplies the multiplier 1050. Output

The NCO 1060 generates a complex signal corresponding to the approximate frequency offset output from the known data position detection and frequency offset determiner 1020 and outputs the complex signal to the multiplier 1050.

The multiplier 1050 multiplies the complex data of the NCO 1060 by the known data output from the known data extractor 1030 and outputs the known data whose frequency offset is compensated to the frequency offset estimator 1070.

The frequency offset estimator 1070 estimates the fine frequency offset from the known data with the approximate frequency offset compensated and outputs the fine frequency offset to the adder 1080.

The adder 1080 adds an approximate frequency offset and a fine frequency offset and outputs the result to the demodulator 902 as an initial frequency offset. That is, the present invention can improve the estimation performance of the initial frequency offset by estimating and using the fine frequency offset as well as the coarse frequency offset when initial synchronization is acquired.

If the received data frame is the same as that of FIG. 22, the known data detection 904 may estimate the initial frequency offset using the correlation of the plurality of first known data patterns in the first known data area.

The field sync position estimated by the known data detector 904 and the known data position information of the second known data pattern region periodically inserted into each known data region are the demodulator 902 and the equalizer 903. Is entered.

The equalizer 903 may perform channel equalization in various ways, and the present invention will describe the channel equalization process through various embodiments.

In this case, as shown in the data structure of FIG. 6A, sufficiently long known data is periodically transmitted in the region A, but not sufficiently long known data cannot be transmitted periodically in the B and C regions.

At this time, one data group inputted for equalization is divided into areas A to C, as shown in FIG. 6A, and areas A to A1 to A5, areas B to B1 and B2, and areas C1 to C3. In one embodiment, those separated by.

Therefore, in the present invention, the estimation and application of the channel impulse response (CIR) according to the areas A (A1-A5), B (B1, B2), and C (C1-C3) in the data group will be described as an embodiment. . In addition, the present invention can more stably perform channel equalization by estimating the CIR using known data and field synchronization that know the location and content of the transmission / reception side.

Let CIR estimated from field synchronization in the data structure as shown in FIG. 6A be called CIR_FS, and CIRs estimated from five known data sequences in the A region are called CIR_N0, CIR_N1, CIR_N2, CIR_N3, and CIR_N4 in this order.

According to the present invention, channel equalization is performed on data in a data group using the field synchronization and the CIR estimated from the known data stream. In this case, one of the estimated CIRs may be used as it is according to the characteristics of each region of the data group. In addition, CIR generated by interpolating or extrapolating at least a plurality of CIRs may be used.

Here, interpolation is a function value at some point between Q and S when the function value F (Q) at point Q and the function value F (S) at point S are known for a function F (x). It is meant to estimate, and the simplest example of the interpolation is linear interpolation. The linear interpolation technique is the simplest of many interpolation techniques, and various other interpolation techniques may be used in addition to the above-described methods, and thus the present invention will not be limited to the examples described above.

Also, extrapolation can be used to determine the function value F (Q) at time Q and the function value F (S) at time S for a function F (x). It means to estimate the function value at the time point. The simplest example of such extrapolation is linear extrapolation. The linear extrapolation technique is the simplest of many extrapolation techniques, and various other extrapolation techniques can be used in addition to the above-described methods.

25 is a flowchart showing an embodiment of a channel equalization method according to the present invention. After temporarily storing a received data group (step 931), the CIR is estimated using field synchronization and known data in the data group ( Step 932). In this case, the step 931 may store all data in the data group or only some data. This means that the data of the B1, C1, A1 area is received before the known data of the first known data area in the corresponding data group. This is done by using

For example, in the case of the C1 region, CIR_FS estimated in the field sync interval of the current data group and CIR_N0 estimated in the first known data region may be extrapolated, and channel equalization may be performed using the extrapolated CIR (step S). 933). Alternatively, channel equalization may be performed using one of CIR_N4 estimated in the previous data group and CIR_FS estimated in the current data group to perform channel equalization. If the extrapolated CIR is used to equalize the data of the C1 region, the data of the C1 region is data that is input before the first known data region in the current data group and should be stored until the CIR_N0 is estimated. In this case, the data storage of the C1 region may be allocated by storing a partial region of an external memory (eg, RAM) in the receiving system, or may be provided with a separate memory.

In the case of the B1 region, various methods are applicable as in the C1 region. In one embodiment, channel equalization may be performed using CIR generated by linear extrapolation of CIR_FS and CIR_N0 estimated in the current data group (step 933). Alternatively, channel equalization may be performed using the CIR_FS estimated from the current data group. Similarly, since the data of the B1 region is the data inputted earlier than the first known data region in the current data group, it should be stored until the CIR_N0 (or CIR_FS) is estimated. The data storage of the B1 region may be allocated and stored as a partial region of an external memory (eg, RAM) in the receiving system, or may be provided with a separate memory.

In the case of the A1 region, channel equalization may be performed using a CIR generated by interpolating CIR_FS and CIR_N0 estimated in the current data group (step 934). Alternatively, channel equalization may be performed using any one of CIR_FS and CIR_N0 estimated by the current data group. If the data of the area A1 is equalized using the interpolated CIR, the data of the area A1 is also inputted before the first known data area in the current data group, and thus should be stored until the CIR_N0 is estimated. In this case, the data storage of the A1 region may be allocated and stored as a partial region of an external memory (eg, RAM) in the receiving system, or may be provided with a separate memory.

In the areas A2 to A5, channel equalization may be performed using CIR generated by interpolating CIR_N (i-1) and CIR_N (i) estimated in the current data group (step 935). Alternatively, channel equalization may be performed using any one of CIR_N (i-1) and CIR_N (i) estimated in the current data group.

In the B2, C2, and C3 regions, channel equalization may be performed using CIR generated by extrapolating CIR_N3 and CIR_N4 estimated by the current data group (step 936). Alternatively, channel equalization may be performed using CIR_N4 estimated from the current data group.

In this way, optimum performance can be obtained at the time of channel equalization for the data inserted in the data group.

Figure 26 is a block diagram showing an embodiment of a channel equalizer to which the present invention is applied.

Referring to FIG. 26, a memory 1500, an overlap unit 1501, a first FFT unit 1502, a distortion compensator 1503, a CIR estimator 1504, and a CIR calculator 1505 are illustrated. , A zero-padding unit 1506, a second FFT unit 1507, a coefficient calculator 1508, an IFFT unit 1509, and a save unit 1510.

The distortion compensation unit 1503 may be any element that performs a complex multiplication role.

In FIG. 26 configured as described above, the received data is temporarily stored in the storage unit 1500 and then output to the overlapping unit 1501. For example, the storage unit 1500 estimates equalization of data of at least one of the regions C1, B1, and A1 of the data group using field synchronization and known data received later than the data of the region A1. Required when extrapolating or interpolating CIR_FS and CIR_N0. That is, the storage unit 1500 stores data of the regions C1, B1, and A1 until at least CIR_FS and CIR_N0 are estimated.

The overlapping unit 1501 overlaps the data output from the storage unit 1500 at a preset overlapping rate and outputs the data to the first FFT unit 1502. The first FFT unit 1502 converts overlapping data in the time domain into overlapping data in the frequency domain through an FFT, and outputs the overlapped data in the distortion compensator 1503.

The distortion compensator 1503 complexes the equalization coefficient calculated by the coefficient operator 1508 to the overlapping data of the frequency domain output from the first FFT unit 1502, and outputs the overlapping output from the first FFT unit 1502. The channel distortion of the data is compensated for and then output to the IFFT unit 1509. The IFFT unit 1509 IFFTs the overlapped data whose distortion of the channel is compensated, converts the data into a time domain, and outputs the converted data to the save unit 1510. The save unit 1510 extracts and outputs only valid data from overlapping data of the channel equalized time domain.

Meanwhile, the CIR estimator 1504 generates an impulse response (CIR_N0 to CIR_N4) of a channel by using the data received during the known data interval and the known data of the known data interval known to the receiving side by the appointment of the transmitting / receiving side. Estimate. To this end, the CIR estimator 1504 is provided with known data position information from which the second known data pattern is transmitted from the known data detector 904. In addition, since the second known data pattern of the known data section is data already known by an appointment of a transmitting / receiving side, the second known data pattern may be stored in the CIR estimator 1504 in advance, and the second generated data may be stored in the known data detector 904. It is also possible to receive a known data pattern.

In addition, the CIR estimator 1504 estimates the impulse response (CIR_FS) of the channel using the data received during the field sync interval and the field sync data of the field sync interval known to the receiver by an appointment of the transmitter / receiver side. do. To this end, the CIR estimator 1504 is provided with field sync position information from the known data detector 904. In addition, since the field synchronization data of the field synchronization section is already known by the appointment of the transmitting / receiving side, the field synchronization data may be stored in the CIR estimator 1504 in advance, and the field synchronization data generated by the known data detector 904 may be stored. You can also receive input.

The CIR estimator 1504 may estimate a channel impulse response (CIR) in a least square (LS) manner.

The CIR estimated by the CIR estimator 1504 is input to the CIR calculator 1505. The CIR calculator 1505 bypasses the estimated CIR according to the area information of the data to be compensated to the zero padding unit 1506 or interpolates or extrapolates the estimated CIR to the zero padding unit 1506. . In this case, it is assumed that the CIR calculator 1505 knows which region of the data frame and / or data group is data to compensate for the channel distortion. For example, if the data to be compensated by the distortion compensator 1503 is data of the B1 region, the CIR calculator 1505 extrapolates CIR_FS and CIR_NO estimated from the current data group to the zero padding unit 1506. . As another example, if the data to be compensated by the distortion compensator 1503 is data of the area A1, the CIR calculator 1505 interpolates CIR_FS and CIR_NO estimated by the current data group and outputs the interpolated data to the zero padding unit 1506.

In this case, a first CIR cleaner which operates only when extrapolation is performed by the CIR calculator 1505 may be further provided at the front end of the CIR calculator 1505, and the CIR calculator 1505 may be provided at an output of the CIR calculator 1505. The second CIR cleaner which operates only when performing interpolation may be further provided.

That is, the CIR estimated from the known data includes not only the channel component to be obtained but also the jitter component due to noise. This jitter component is a factor that degrades the equalizer performance, so it is better to remove it before using the CIR in the coefficient calculator 1508. Accordingly, in the first and second CIR cleaners, an embodiment in which the portion of the CIR input power whose power is equal to or less than a predetermined threshold is removed (that is, made into '0'). This removal process is called CIR cleaning.

CIR interpolation in the CIR calculator 1505 is performed by multiplying and adding a coefficient to two CIRs estimated by the CIR estimator 1504, respectively. At this time, some of the noise components of the CIR are added to each other to cancel. Therefore, when CIR interpolation is performed in the CIR calculator 1505, the original CIR in which the noise component remains is used. For example, when CIR interpolation is performed by the CIR calculator 1505, the first CIR cleaner does not operate, and the CIR interpolated by the CIR calculator 1505 may be cleaned by the second CIR cleaner.

On the other hand, the CIR extrapolation in the CIR calculator 1505 is performed by estimating the CIR located outside the two CIRs by using the difference between the two CIRs estimated by the CIR estimator 1504. Therefore, the noise component of the CIR is amplified at this time. Accordingly, when the CIR extrapolation is performed by the CIR calculator 1505, the first CIR cleaner may be operated to clean the estimated CIR and then input the CIR calculator 1505. At this time, the second CIR cleaner does not operate, and the CIR extrapolated by the CIR calculator 1505 is directly input to the zero padding unit 1506.

Meanwhile, when the CIR of the time domain input from the second FFT unit 1507 is converted into the frequency domain, the length of the input CIR and the FFT size may not match. That is, a case where the length of the CIR is smaller than the FFT size may occur. In this case, the zero padding unit 1506 adds '0' to the CIR by the difference between the FFT size and the input CIR length and outputs the same to the second FFT unit 1507. The zero-padded CIR may be one of interpolated CIRs, extrapolated CIRs, and CIRs estimated from known data intervals.

The second FFT unit 1507 converts the input CIR of the time domain into a CIR of the frequency domain, and outputs the CIR to the coefficient calculator 1508. The coefficient calculator 1508 calculates an equalization coefficient by using the converted CIR of the frequency domain and outputs the equalization coefficient to the distortion compensator 1503. In this example, the coefficient calculator 1508 may obtain an equalization coefficient for minimizing the mean square error (MMSE) from the CIR of the frequency domain and output the equalization coefficient to the distortion compensator 1503.

Meanwhile, as described above, the channel equalized data in the equalizer 903 is input to the block decoder 905. The block decoder 905 performs trellis decoding and additional decoding on the reverse side of the transmitting side if the input data is mobile service data in which both additional encoding and trellis encoding are performed at the transmitting side, and additional encoding is not performed. If trellis encoding is the main service data, only trellis decoding is performed.

The data group decoded by the block decoder 905 is input to the data deformatter 906, and the main service data is input to the data deinterleaver 909. In another embodiment, the main data may be bypassed in the block decoder 905 and input to the data deinterleaver 909. In this case, a trellis decoder for main service data must be provided in front of the data deinterleaver 909.

When the block decoder 905 outputs the data group to the data deformatter 906, the known data, trellis initialization data, the MPEG header, and the RS encoder / unstructured RS encoder of the transmission system have been inserted into the data group. Alternatively, the RS parity added by the unstructured RS encoder is removed and output to the data deformatter 906. Here, data removal may be performed before block decoding, or may be performed during or after block decoding. If the transmitting side includes signaling information in the data group and transmits the signaling information, the signaling information is output to the data deformatter 906.

That is, if the input data is main service data, the block decoder 905 may perform Viterbi decoding on the input data to output a hard decision value, or hard decision the soft decision value and output the result.

If the input data is mobile service data, the block decoder 905 outputs a hard decision value or a soft decision value with respect to the input mobile service data.

That is, if the input data is mobile service data, the block decoder 905 decodes the data encoded by the block processor and the trellis encoder of the transmission system. At this time, the RS frame coder of the preprocessor on the transmitting side becomes an external code, and the block processor and trellis coder can be regarded as one internal code.

In order to maximize the performance of the outer code at the time of decoding the concatenated code, the soft decision value should be output from the decoder of the inner code.

Therefore, the block decoder 905 may output a hard decision value for the mobile service data, but it may be better to output a soft decision value if necessary.

Meanwhile, the data deinterleaver 909, the RS decoder 910, and the derandomizer 911 are blocks necessary for receiving main service data, and may not be necessary in a reception system structure for receiving only mobile service data. have.

The data deinterleaver 909 deinterleaves the main service data output from the block decoder 905 in the reverse process of the data interleaver of the transmitting side, and outputs the main service data to the RS decoder 910.

The RS decoder 910 performs systematic RS decoding on the deinterleaved data and outputs the deserializer 911.

The derandomizer 911 receives the output of the RS decoder 910 to generate the same pseudo random bytes as the transmitter's renderer, bitwise XORs the MPEG sync bytes to each packet. Insert before and output in 188 byte main service data packet unit.

The data output from the block decoder 905 to the data formatter 906 is a data group type. In this case, the data deformatter 906 knows the configuration of the input data group and distinguishes the signaling information having the system information from the mobile service data in the data group. The divided signaling information is transmitted to a block (not shown) that processes the signaling information, and the mobile service data is output to the RS frame decoder 907.

That is, the RS frame decoder 907 receives only RS coded and CRC coded mobile service data from the data deformatter 906.

The RS frame decoder 907 performs an inverse process in the RS frame encoder of the transmission system to correct errors in the RS frame, and then removes one byte of MPEG synchronization from the RS frame encoding process in the error corrected mobile service data packet. The bytes are added and output to the derandomizer 908. The detailed operation of the RS frame decoder 907 will be described later.

The de-randomizer 908 performs de-randomization corresponding to the reverse process of the renderer of the transmission system and outputs the received mobile service data, thereby obtaining mobile service data transmitted from the transmission system.

The following is a detailed operation of the RS frame decoder 907.

27 is a diagram illustrating an embodiment of an error correction decoding process of the RS frame decoder 907 in sequence.

That is, the RS frame decoder 907 collects mobile service data received from the data formatter 906 to form an RS frame. The mobile service data is RS coded and CRC coded data in a transmission system.

27 (a) shows an example of configuring an RS frame. That is, assuming that the transmission system divides (N + 2) * 235 RS frames into 30 * 235 byte blocks, and inserts and transmits the mobile service data of each divided block into each data group, The mobile service data of the 30 * 235 byte block inserted in the data group is collected to form an (N + 2) * 235 RS frame. For example, assuming that an RS frame is divided into 18 30 * 235 byte blocks and transmitted in one burst period, the receiving system configures an RS frame by collecting mobile service data of 18 data groups in the burst period. In addition, assuming that N is 538, the RS frame decoder 907 may collect mobile service data in 18 data groups in one burst to configure an RS frame having a size of 540 * 235 bytes.

In this case, assuming that the block decoder 905 outputs a decoding result as a soft decision value, the RS frame decoder 907 may determine 0 and 1 of the corresponding bit as a sign of the soft decision value. The eight are gathered together to form one byte. Performing this process on all of the soft decision values of 18 groups of data in one burst makes it possible to construct an RS frame of size 540 * 235 bytes.

In addition, the present invention not only uses the soft decision value to construct an RS frame, but also to construct a reliability map.

The credit map indicates whether or not the corresponding byte formed by collecting eight bits determined by the sign of the soft decision value is reliable.

In an embodiment, when the absolute value of the soft determination value exceeds a preset threshold, the corresponding bit value determined by the sign of the soft determination value is determined to be reliable, and when it is not exceeded, it is determined to be unreliable. Then, in the case where it is determined that even one bit in one byte composed of eight bits determined by the sign of the soft decision value is unreliable, the credit map indicates that the byte is unreliable. Here, one bit is an embodiment, and when a plurality of, for example, four or more bits are determined to be unreliable, it may indicate that the corresponding byte is not reliable in the credit map.

On the contrary, when all bits in one byte are determined to be reliable, that is, when the absolute value of the soft decision value of all bits of one byte exceeds a preset threshold, the corresponding map is marked as reliable. Similarly, if a plurality of bits in one byte, for example, four or more bits are determined to be reliable, the credit map indicates that the bytes are reliable.

The above-described numerical values are merely examples, and the scope of the present invention is not limited to the numerical values.

The configuration of the RS frame and the configuration of the credit map using the soft decision value can be performed simultaneously. At this time, the credit information in the credit map corresponds 1: 1 to each byte in the RS frame. For example, if one RS frame is 540 * 235 bytes in size, the credit map is 540 * 235 bits in size. Figure 27 (a ') shows a process of forming a credit map according to the present invention.

On the other hand, the RS frame decoder 907 checks whether an error occurs in each row by performing a CRC syndrome check on the RS frame having a size of (N + 2) * 235 bytes. Subsequently, as shown in FIG. 27 (b), an RS frame having a size of N * 235 bytes is formed by removing a 2-byte CRC checksum, and an error flag is indicated on an error flag corresponding to each row. Similarly, since the portion of the credit map corresponding to the CRC checksum is not utilized, this portion is removed to leave only N * 235 credit information as shown in FIG. 27 (b ').

After the CRC syndrome check is performed, the RS frame decoder 907 performs RS decoding in the column direction. In this case, RS erasure correction may be performed according to the number of CRC error flags. That is, as shown in (c) of FIG. 27, the CRC error flag corresponding to each row in the RS frame is examined, and the maximum number of RS erasure corrections can be performed when the number of rows with an error is performed in the column direction RS decoding. Determine if it is less than or equal to the number of errors. The maximum number of errors is the number of parities inserted during RS encoding. In the present invention, it is assumed that 48 parity bytes are added to each column.

If the number of rows having a CRC error is less than or equal to the maximum number of errors that can be corrected by RS erasure decoding (48 according to the embodiment), RS having 235 N byte rows as shown in FIG. (235, 187) -RS erasure decoding is performed on the frame and 48-byte parity data added to the end of each column is removed as shown in FIG. 27 (f).

However, if the number of rows having a CRC error is larger than the maximum number of errors that can be corrected by RS erasure decoding (that is, 48), RS erasure decoding cannot be performed.

In this case, error correction may be performed through general RS decoding. In addition, the present invention can further improve error correction capability by using a credit map generated when constructing an RS frame from the soft decision value.

That is, the RS frame decoder 907 compares the absolute value of the soft decision value of the block decoder 905 with a preset threshold value and determines the credit of the bit value determined by the sign of the soft decision value. Credit information for the corresponding byte formed by collecting eight bits determined by the sign of the soft decision value was displayed on the credit map.

Therefore, the present invention does not assume that all bytes of a row have an error even if it is determined that there is a CRC error as a result of the CRC syndrome check of a specific row as shown in FIG. Set the error to only those bytes that are considered unreliable. That is, only the bytes determined to be unreliable in the credit information of the credit map regardless of the CRC error of the corresponding row are set as erasure points.

Alternatively, the CRC syndrome check determines that there is a CRC error in the row, and sets an error only for bytes determined that the credit information of the credit map is unreliable. That is, only a byte having a CRC error in a corresponding row and determined to be unreliable in credit information of a credit map is set as an erasure point.

Then, if the number of error points for each column is less than or equal to the maximum error number that can be corrected by RS erasure decoding (that is, 48), RS erasure decoding is performed on the column. On the contrary, if the number of error points is larger than the maximum number that can be modified by RS erasure decoding (that is, 48), general RS decoding is performed on the column.

That is, if the number of rows with CRC errors is greater than the maximum number of errors that can be corrected by RS erasure decoding (for example, 48), then the corresponding columns are determined according to the number of erasure points in the corresponding column determined by the credit information of the credit map. RS erasure decoding is performed or general RS decoding is performed.

For example, the number of rows having a CRC error in the RS frame is greater than 48, and the number of erasure points determined by the credit information of the credit map is 40 in the first column and 50 in the second column. Suppose Then, (235,187) -RS erasure decoding is performed on the first column, and (235,187) -RS decoding is performed on the second column.

When error correction decoding is performed in all column directions in the RS frame by performing the above process, as shown in FIG. 27 (f), 48-byte parity data added to the end of each column is removed.

As described above, in the present invention, even if the total number of CRC errors corresponding to each row in the RS frame is larger than the maximum number of errors that can be corrected by RS erasure decoding, the credit information of the corresponding column in the credit map of the corresponding column is corrected. As a result, if the number of bytes with low credit is equal to or smaller than the maximum error number correctable by RS erasure decoding, RS erasure decoding may be performed on the column.

Here, the difference between general RS decoding and RS erasure decoding is the number of correctable errors. That is, by performing normal RS decoding, errors can be corrected by the number corresponding to (number of parity) / 2 (eg, 24) inserted in the RS encoding process, and when RS erasure decoding is performed, RS encoding process is performed. An error may be corrected by the number of parities inserted (e.g., 48).

After the error correction decoding is performed as described above, an RS frame having 187 N-byte rows (that is, a packet) can be obtained as shown in FIG. 27 (f). RS frames of size N * 187 bytes are output in the order of N 187 bytes in size. In this case, as shown in (g) of FIG. In addition, the mobile service data packet in units of 188 bytes is output.

The present invention described so far is not limited to the above-described embodiments, and can be modified by those skilled in the art as can be seen from the appended claims, and such modifications are the scope of the present invention. Belongs to.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

1 is a schematic structural block diagram of a digital broadcasting system according to an embodiment of the present invention;

2 is a block diagram showing an embodiment of the service multiplexer of FIG.

3 is a block diagram illustrating an embodiment of the transmitter of FIG.

4 is a block diagram illustrating an embodiment of the preprocessor of FIG. 3.

5A to 5E illustrate error correction encoding and error detection encoding processes according to an embodiment of the present invention.

6A and 6B illustrate examples of data configurations before and after the data deinterleaver in the transmission system according to the present invention.

7 illustrates an embodiment of a process of dividing an RS frame to form a data group according to the present invention.

8 illustrates an example of an operation of a packet multiplexer for transmitting a data group according to the present invention.

9 is a block diagram illustrating an embodiment of a block processor according to the present invention.

10 is a detailed block diagram illustrating an embodiment of the symbol encoder of FIG. 9.

11 (a) to (c) illustrate an embodiment of a variable length interleaving process of the symbol interleaver of FIG.

12A and 12B are block diagrams illustrating another embodiment of a block processor according to the present invention.

13A to 13C illustrate examples of a block encoding and trellis encoding process according to the present invention.

14 is a block diagram showing an embodiment of a trellis encoder according to the present invention.

15A and 15B are diagrams illustrating a state in which a block processor and a trellis encoder are connected according to the present invention.

16 illustrates another embodiment of a block processor according to the present invention.

17 shows another embodiment of a block processor in accordance with the present invention.

18 illustrates an embodiment for inserting and transmitting a transmission parameter in a group formatter according to the present invention.

19 illustrates an embodiment for inserting and transmitting a transmission parameter in a block processor according to the present invention.

20 illustrates an embodiment for inserting and transmitting a transmission parameter in a packet formatter according to the present invention.

21 is a block diagram showing an embodiment of a receiving system according to the present invention;

22 illustrates a portion of a data frame transmitted in accordance with the present invention.

23 is a flowchart showing an embodiment of a known data detection process according to the present invention.

24 is a block diagram illustrating an embodiment of the known data detector of FIG. 21.

25 is a flowchart illustrating an embodiment of a channel equalization process according to the present invention.

FIG. 26 is a block diagram illustrating an embodiment of the channel equalizer of FIG. 21.

27 shows an example of an error correction decoding process according to the present invention.

* Description of the symbols for the main parts of the drawings *

901 tuner 902 demodulator

903: Equalizer 904: Known Data Detector

905: block decoder 906: data formatter

907 RS frame decoder 908,911 data derandomizer

909: data deinterleaver 910: RS decoder

1500: storage unit 1501: overlapping unit

1502: first FFT unit 1503: distortion compensation unit

1504: CIR estimator 1505: CIR calculator

1506: zero padding portion 1507: second FFT portion

1508: coefficient calculator 1509: IFFT unit

1510: save part

Claims (20)

Mobile service data, one first known data string forming a first pattern mutually known in a transmission / reception system, and a plurality of second known data strings forming a second pattern different from the first pattern. A signal receiver configured to receive a broadcast signal including a data group, wherein the second patterns of the plurality of second known data columns are located at intervals of 16 segments in the data group; A known data detector for detecting first and second known data streams from the broadcast signal; An estimator estimating a channel impulse response (CIR) using a second pattern of the detected second known data stream; And And a distortion compensator for compensating for channel distortions generated in the mobile service data using the estimated CIR. The method of claim 1, And an operation unit for generating a CIR by interpolating or extrapolating a plurality of channel impulse responses (CIR) estimated by the estimator, and outputting the generated CIR to the distortion compensation unit. Receiving system. The method of claim 1, wherein the distortion compensation unit And calculating an equalization coefficient based on the estimated CIR and compensating for channel distortion generated in the mobile service data using the calculated equalization coefficient. The method of claim 1, And the first pattern of the first known data stream is configured by repeating the same pattern at least twice. The method of claim 1, And a first pattern of the first known data stream is used for synchronous recovery of the mobile service data. The method of claim 1, The lengths of the plurality of second known data columns are different from each other, and a second pattern is positioned from an end symbol to a preceding N symbol for each of the second known data columns. delete The method of claim 1, And a transmission parameter is received between the first known data string and the second known data string. The method of claim 1, And a block decoder for performing block decoding on the mobile service data whose channel distortion is compensated for. The method of claim 9, And an error correction unit configured to correct an error generated in the mobile service data by performing error correction decoding on the block decoded mobile service data. Mobile service data, one first known data string forming a first pattern mutually known in a transmission / reception system, and a plurality of second known data strings forming a second pattern different from the first pattern. Receiving a broadcast signal including a data group, wherein the second patterns of the plurality of second known data columns are positioned at 16 segment intervals within the data group; Detecting first and second known data streams from the broadcast signal; Estimating a channel impulse response (CIR) using a second pattern of the detected second known data streams; And Compensating for channel distortion generated in the mobile service data using the estimated CIR. The method of claim 11, And interpolating or extrapolating the estimated plurality of channel impulse responses (CIRs) to further generate CIRs, and outputting the generated CIRs to the channel distortion compensation step. Method of processing data in the receiving system. The method of claim 11, wherein the distortion compensation step Calculating an equalization coefficient based on the estimated CIR, and compensating for channel distortion generated in the mobile service data using the calculated equalization coefficient. The method of claim 11, And the first pattern of the first known data stream is configured by repeating the same pattern at least twice. The method of claim 11, And a first pattern of the first known data stream is used for restoring synchronization of the mobile service data. The method of claim 11, The lengths of the plurality of second known data columns are different from each other, and a second pattern is located from an end symbol to a preceding N symbol for each of the second known data columns. delete The method of claim 11, And a transmission parameter is received between the first known data string and the second known data string. The method of claim 11, And performing block decoding on the mobile service data whose channel distortion is compensated for. The method of claim 19, And performing error correction decoding on the block decoded mobile service data to correct an error generated in the mobile service data.

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