KR100538077B1 - Apparatus for transmitting digital signal and method of the same - Google Patents

Abstract

Disclosed are a digital radio relay apparatus and method. The receiver receives a broadcast signal from the satellite. The broadcast data generator generates broadcast data by encoding the received broadcast signal for each channel by a code division method. The additional data generator generates additional data by encoding the additional information including the repeater identification information and the repeater status information by a code division method. The multiplexer multiplexes and outputs the broadcast data and the additional data generated by the plurality of broadcast data generators. The transmitter transmits the multiplexed data. According to the present invention, it is possible to grasp the state of a repeater remotely by using a component for relaying a broadcast signal, thereby facilitating maintenance and repair of the repeater.

Description

Apparatus for transmitting digital signal and method of the same}

The present invention relates to a digital radio relay apparatus and method, and more particularly, to a digital radio relay apparatus and method for converting and transmitting a digital multimedia broadcasting signal received from a satellite into a terrestrial signal.

Digital broadcasting standards are largely divided into European DVB (Digital Video Broadcasting) method and American VSB (Vestigial Sideband Broadcasting) method. Among them, Korea adopts VSB as a standard for digital TV. However, in the case of DAB (Digital Audio Broadcasting), the DVB method is adopted as a standard, and DAB was initially limited to radio broadcasting using satellites, but gradually evolved into DMB (Digital Multimedia Broadcasting) capable of providing video services.

The DVB method improves the commonality of various media such as cable TV, satellite, terrestrial antenna, and public antenna (SMATV). The encoding and compression of signals is based on MPEG2. In addition, the subscriber management function (Conditional Access) is prescribed to be based on a common scrambling algorithm. The DVB system has substandards such as satellite digital TV broadcasting DVB-S (Satellite), digital cable TV broadcasting DVB-C (Cable), and terrestrial digital broadcasting DVB-T.

Digital system E specified in ITU-R BO.1130-4 RECOMMENDATION among the systems for DMB service converts satellite signals transmitted by DVB-S method into CDM (Code Division Multiplexing) signals that the terminal can receive and transmits them. Use a repeater. Repeaters that play this role are commonly referred to as gap fillers. The gap filler is a low power retransmission station that receives and retransmits radio waves emitted from a transmission station so that broadcasts can be received in an area where radio waves are shielded, such as a high density building and a tunnel.

However, the current gap filler simply performs the function of converting the signal received from the satellite into a CDM signal and transmitting the CDM signal. Thus, the state of the repeater (for example, the strength of the signal transmitted from the repeater, the failure of the repeater, In order to grasp the reception status), the repeater operator has to check the status of the repeater directly.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a digital wireless relay apparatus and method capable of transmitting status information of a repeater using a broadcast signal transmission method.

In order to achieve the above technical problem, the digital wireless relay device according to the present invention comprises: a receiver for receiving a broadcast signal from a satellite; A plurality of broadcast data generation units encoding a plurality of broadcast data by encoding the received broadcast signal by a code division method for each channel; An additional data generation unit encoding additional information including repeater identification information and repeater status information by a code division method to generate additional data; A multiplexer for multiplexing and outputting the plurality of broadcast data and the additional data; And a transmitter for transmitting the multiplexed data.

The additional data generator may include an information generator configured to generate a predetermined data packet based on the additional information; A modulator for QPSK modulating the data packet; A first spreader configured to spread the modulated data packet using a first PN code; And a second spreader configured to spread the spread data packet using a second PN code.

The data packet includes an identification information field in which the repeater identification information is recorded; And a message field in which the repeater state information is recorded, wherein the predetermined number of lower bits constituting the identification information field coincides with an offset value of the second PN code.

The broadcast data is transmitted in a unit of a superframe composed of a predetermined number of subframes, and the start point of the additional data is transmitted in accordance with the start point of the superframe.

According to another aspect of the present invention, there is provided a digital wireless relay method comprising: receiving a broadcast signal from a satellite; Generating a plurality of broadcast data by encoding the received broadcast signal for each channel by a code division method; Generating additional data by encoding the additional information including the repeater identification information and the repeater status information by a code division method; Multiplexing the plurality of broadcast data and the additional data; And transmitting the multiplexed data.

Preferably, the additional data generation step, generating a predetermined data packet based on the additional information; QPSK modulating the data packet; Spreading the modulated data packet using a first PN code; And spreading the spread data packet using a second PN code.

The data packet includes an identification information field in which the repeater identification information is recorded; And a message field in which the repeater state information is recorded, wherein the predetermined number of lower bits constituting the identification information field coincides with an offset value of the second PN code.

The broadcast data is transmitted in a unit of a superframe composed of a predetermined number of subframes, and the start point of the additional data is transmitted in accordance with the start point of the superframe.

As a result, the repeater state can be grasped remotely by using a component for relaying a broadcast signal, thereby facilitating maintenance and repair of the repeater.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the digital radio relay apparatus and method according to the present invention.

1 is a block diagram showing the configuration of an embodiment of a digital wireless relay device according to the present invention.

Referring to FIG. 1, the digital wireless relay apparatus 100 includes a receiver 110, a broadcast data generator 120, 130, and 140, an additional data generator 150, a multiplexer 160, and a transmitter 170. It is provided.

The receiver 110 receives a signal to be relayed. In the case of a gap filler for digital system E of ITU-R BO.1130-4 RECOMMENDATION, the receiver 110 receives a DVB-S broadcast signal from a satellite. The signal received by the receiver 110 includes clock information such as a frame and a symbol. The receiver 110 includes a digital baseband receiver, and the digital baseband receiver extracts a clock by performing frame, symbol synchronization acquisition, and tracking.

The broadcast data generation unit 120, 130, 140 encodes the signal received from the satellite by code division method for each channel to generate broadcast data. Each broadcast data generating unit 120, 130, 140 includes a modulator 122, 132, 142, an orthogonal diffusion unit 124, 134, 144, and a diffusion unit 126, 136, 146.

The modulators 122, 132, and 142 modulate the broadcast signal received for each broadcast channel through the receiver 110 in a QPSK modulation scheme. Since the QPSK modulation method is easily understood by those skilled in the art, detailed description thereof will be omitted.

The orthogonal spreading units 124, 134, and 144 spread the modulated broadcast signal using Walsh codes having orthogonality. Walsh codes are multiplied by different codes (Exclusive OR), resulting in a mixture of 0 (or -1) and 1, all averaged to 0, and multiplying by the same code results in all 1s resulting in data hidden in the spread signal. This is a recoverable code. At present, 32 channels exist in DMB system. For this purpose, orthogonal diffusion process is performed on data existing in each channel by 64-bit Walsh code.

The spreaders 126, 136, and 146 spread the orthogonally spread broadcast signal using the same PN code for the I / Q path. Walsh code is characterized as orthogonality, but it is vulnerable to multipath interference, so PN code is used to compensate for it. The broadcast signal spread from the spreaders 126, 136, and 146 is input to the multiplexer 160.

The additional data generator 150 generates additional data by encoding the additional information including the repeater ID and the repeater state information by a code division method. The additional data generator 150 includes an information generator 152, a modulator 154, a first spreader 156, and a second spreader 158.

The information generating unit 152 generates a data packet based on additional information including the status information of the repeater including the strength of the signal transmitted from the repeater, whether the repeater is broken, the reception status of the satellite signal, and the ID of the repeater. do. 2 shows a format of a data packet generated by the information generator 152. Referring to FIG. 2, a data packet includes an 8-bit flag and a payload of 1 to 296 bits.

The flag consists of 8 bits, all of which have a value of zero. The flag is used to promptly confirm the search result for the additional data channel transmitted from the relay apparatus 100. The payload consists of a header field, a message field, and a CRC field. The header and the CRC are always sent and the message can be omitted. The header consists of a type field, a repeater ID field, a flag termination field, and a length field. The type field is a field in which type information of a message recorded in a message field is recorded. The type field is composed of one bit indicating whether the data packet is divided or transmitted from the most significant bit and three bits indicating the type of the message. When the partition information bit is 0, one message is transmitted independently, and when 1, the partition information bit is divided in order. When the split information bit is 1, the split information bit may be divided into 8 packets and transmitted. In the transmission of the divided packets, no other packets can be transmitted before the last packet is transmitted.

The repeater identification information field consists of 20 bits and the lower 7 bits must match the offset of the long code. That is, the offset of the long code is given by the value of the lower 7 bits of the repeater identification information field x 20483. The receiving apparatus determines that the repeater ID is confirmed when the offset information included in the repeater identification information field and the offset value of the long code match.

The split end field has meaning only when the split information bit of the type field is one. A total of 8 divided packets can be transmitted in order. If a packet is divided into fewer than 8 packets and is transmitted, the receiving terminal knows that the packet is the final packet by setting the split end field of the last packet to 1.

The length field is a field in which length information of a message is recorded. The unit is bytes. The message is 31 bytes maximum. The actual bits used are 5 bits and the range is 0-31. If the length is 0, there is no message field, and the CRC field immediately follows the header field.

The message field includes network management system (NMS) information, status information of the repeater, and the length of the message field varies depending on the content of the information. NMS is software that system administrators use to control the network. The NMS may consist of one program or a series of programs. The receiving device can know the length of the message field by the length value recorded in the length field in the header. If the length is zero, there is no message field. On the other hand, when the length of the message field is long, the message may be transmitted in the form of a single packet or a divided packet using the type field of the header.

In the CRC field, an error correction code for checking the accuracy of the header and the message information received from the receiving apparatus is recorded. The CRC field is 16 bits, and the CRC is generated by the 16-bit CRC-CCITT generator polynomial. The CRC-CCITT constructor polynomial is

The initial value of the generator polynomial uses the lower 16 bits of the repeater ID. Generation of CRC Parity starts from the beginning of the payload. 3 shows an example of a circuit for generating a CRC value.

The modulator 154 modulates the additional information generated by the information generator 152 by the QPSK modulation method. The first spreader 156 spreads the additional information modulated by the PN code used by the spreaders 126, 136, and 146 of the broadcast data generator 120, 130, and 140. The PN code may perform a data spreading process using different codes for each repeater. However, if a different PN code is used for each repeater, there is a problem in that the receiving apparatus must reproduce or memorize all the PN codes of the repeater. Therefore, it is preferable to use the same PN code in all repeaters, but to shift the phases of the PN codes at regular intervals for each repeater to distinguish the repeaters. The second spreader 158 respreads the additional information spread by the first spreader 156 by the long PN code. The long PN code is generated by the long code generating device shown in FIG. 4 and input to the second spreading unit 158. Alternatively, the long code raw growth value may be provided in the second diffusion unit 158. Referring to FIG. 4, the long code raw growth value generates a long code of Truncated M-sequence having a frame length of one frame length (208896 chips per frame). Uses a feedback transition register sequence (period 262143). The initial value of the long code generator is preferably set to 400000 (octal).

The long code is transmitted with a time delay corresponding to the offset within the frame. Since there are 208896 chips in one frame, 102 offsets can be constructed by giving a time delay of 2048 chips. The reason for giving the time delay to the value corresponding to 2048 chips is to prevent reception errors due to multipath. This long code determines the lower 7 bits of the repeater identification field.

The multiplexer 160 multiplexes the broadcast data input from the broadcast data generators 120, 130, and 140 and the additional data input from the additional data generator 150. The transmitter 170 transmits the multiplexed data.

The additional channel described above has a data rate of 4Kbps, and the data is modulated by the BPSK modulation method because QPSK modulation is performed by repeating the data 128 times without performing a separate channel coding process. In addition, the modulated data is continuously spread by the short code and the long code. On the other hand, the additional channel is divided by the long code offset for the superframe of the broadcast channel, the gain of the additional channel is 1/16, 24dB lower than the broadcast channel. Furthermore, the start of the message packet transmitted by the additional channel coincides with the start of the superframe. 5 shows the transmission time of the superframe and the message packet.

6 is a flowchart illustrating a process of performing an embodiment of a digital wireless relay method according to the present invention.

Referring to FIG. 6, the receiver 110 receives a broadcast signal from a satellite (S600). The broadcast data generation unit 120, 130, 140 modulates the received broadcast signal by the CDM method (S610). The information generation unit 152 generates a data packet based on the additional information including the repeater identification information and the status information (S620). The modulator 154 modulates the generated data packet by the QPSK method (S630). The first spreader 156 spreads the modulated data packet by the PN code used to spread the broadcast signal by the broadcast data generator 120, 130, and 140 (S640). The second spreader 158 respreads the spread data packet with a long PN code having a different offset for each repeater (S650). The multiplexer 160 multiplexes the broadcast signal and the additional information converted by the CDM method (S660). The transmitter 170 transmits the multiplexed signal (S680).

Although the preferred embodiments of the present invention have been shown and described above, the present invention is not limited to the specific preferred embodiments described above, and the present invention belongs to the present invention without departing from the gist of the present invention as claimed in the claims. Various modifications can be made by those skilled in the art, and such changes are within the scope of the claims.

According to the digital wireless relay apparatus and method according to the present invention, the identification information and the status information of the repeater is modulated in the same manner as the modulation method used to convert the broadcast signal received from the satellite into a terrestrial signal and then multiplexed with the broadcast signal. By transmitting the information, it is possible to transmit the status information of the repeater using the components of the existing repeater, it is possible to grasp the status of the repeater by the repeater status information received from the remote can facilitate the maintenance and repair of the repeater .

1 is a block diagram showing the configuration of an embodiment of a digital wireless relay device according to the present invention;

2 is a diagram showing a format of a data packet generated by the information generating unit 152;

3 is a diagram illustrating an example of a circuit for generating a CRC value;

4 is a diagram showing the configuration of a long code generation device that generates a second spreading code;

5 is a diagram illustrating a transmission time point of a superframe and a message packet, and

6 is a flowchart illustrating a process of performing an embodiment of a digital wireless relay method according to the present invention.

Claims (8)

delete A receiver which receives a broadcast signal from a satellite; A plurality of broadcast data generation units for encoding the received broadcast signal for each channel by a code division method to generate broadcast data; An additional data generation unit encoding additional information including repeater identification information and repeater status information by a code division method to generate additional data; A multiplexer for multiplexing and outputting the plurality of broadcast data and the additional data; And A transmission unit for transmitting the multiplexed data; The additional data generation unit, An information generation unit generating a predetermined data packet based on the additional information; A modulator for QPSK modulating the data packet; A first spreader configured to spread the modulated data packet using a first PN code; And And a second spreader configured to spread the spread data packet by using a second PN code. The method of claim 2, The data packet is, An identification information field in which the repeater identification information is recorded; And And a message field in which the repeater state information is recorded. And a predetermined number of lower bits constituting the identification information field coincides with an offset value of the second PN code. A receiver which receives a broadcast signal from a satellite; A plurality of broadcast data generation units for encoding the received broadcast signal for each channel by a code division method to generate broadcast data; An additional data generation unit encoding additional information including repeater identification information and repeater status information by a code division method to generate additional data; A multiplexer for multiplexing and outputting the plurality of broadcast data and the additional data; And A transmission unit for transmitting the multiplexed data; The broadcast data is transmitted in units of a superframe consisting of a predetermined number of subframes, and the start point of the additional data is transmitted in synchronization with the start point of the superframe. delete Receiving a broadcast signal from a satellite; Generating a plurality of broadcast data by encoding the received broadcast signal for each channel by a code division method; Generating additional data by encoding the additional information including the repeater identification information and the repeater status information by a code division method; Multiplexing the plurality of broadcast data and the additional data; And Transmitting the multiplexed data; The additional data generation step, Generating a predetermined data packet based on the additional information; QPSK modulating the data packet; Spreading the modulated data packet using a first PN code; And And spreading the spread data packet using a second PN code. The method of claim 6, The data packet is, An identification information field in which the repeater identification information is recorded; And And a message field in which the repeater state information is recorded. And a predetermined number of lower bits constituting the identification information field coincides with an offset value of the second PN code. Receiving a broadcast signal from a satellite; Generating a plurality of broadcast data by encoding the received broadcast signal for each channel by a code division method; Generating additional data by encoding the additional information including the repeater identification information and the repeater status information by a code division method; Multiplexing the plurality of broadcast data and the additional data; And Transmitting the multiplexed data; The broadcast data is transmitted in units of a superframe consisting of a predetermined number of subframes, and the start point of the additional data is transmitted in synchronization with the start point of the superframe.