JP2014233033A - Device and method for transmission path coding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and a method for transmission path coding to enable a receiver to correctly perform reception/presentation processing of one-segment area broadcasting.SOLUTION: The transmission path coding device includes: a synchronous signal generator unit for generating and outputting a synchronous signal to be a criterion for OFDM symbol generation timing; a signal level converter unit for alternately converting the signal levels of a transmission control signal group in a segment, other than one segment at the center in one frequency channel, into two different signal levels; and an OFDM frame configuration unit for configuring an OFDM frame from the transmission control signal group, output from the signal level converter unit, and a signal for one segment at the center. The signal level converter unit determines the two different signal levels in such a manner that one signal level out of the two different signal levels comes to be a first predetermined level or higher, and a time average of the two different signal levels comes to be a second predetermined level or lower.

Description

  The present invention relates to a transmission technique, and more particularly, to a transmission path encoding apparatus and a transmission path encoding method used in a transmission apparatus that transmits a predetermined signal.

  One-segment broadcasting, which is one of terrestrial digital television broadcasting, is 13 segments included in one frequency channel (6 MHz band) in accordance with “Radio Terrestrial Television Broadcasting Operation Regulations” (ARIB TR-B14) of the Japan Radio Industry Association. Of these, only one central segment on the frequency axis (hereinafter referred to as the central segment) is used. The remaining 12 segments (hereinafter referred to as peripheral segments) are used for HD (High Definition) television broadcasting and the like.

  Furthermore, only the central segment is used in accordance with the “Area Broadcasting Operational Regulations” (ARIB TR-B35) of the Japan Radio Industry Association established in 2012, and the peripheral segments are not used for other HD TV broadcasts ( 1Seg area broadcasting has started.

“Area Broadcasting Operation Regulations ARIB TR-B35 1.1 Version”, Japan Radio Industry Association, September 25, 2012, “Part 2 One-Seg Area Broadcasting”

  However, among conventional one-seg broadcasting-compatible receivers, there are models that perform reception / presentation processing on the assumption that all 13-segment radio waves in the frequency channel are received (hereinafter referred to as a 13-segment receiver). Accordingly, there is a problem that such a 13-segment assumed receiver cannot normally perform the reception / presentation processing of the one-segment area broadcasting.

  In view of the above circumstances, the present invention provides a transmission path encoding apparatus and transmission path code that allow a 13-segment assumed receiver to receive and present a one-segment area broadcast more normally. The purpose is to provide a conversion method.

In order to solve the above problems, the present invention provides the following apparatus and method.
(1) A transmission path encoding device (10) used for a one-segment broadcasting transmission device using only one central segment on the frequency axis among 13 segments included in one frequency channel,
A synchronization signal generator (11) that generates and outputs a synchronization signal that is a reference for generating the OFDM symbol;
Based on the synchronization signal, a transmission control signal group of a peripheral segment that is a segment other than the central one segment in the 13 segments to be broadcast is received as an input, and the signal level of the transmission control signal group is set to two different signals. A signal level converter (12) for alternately converting to a level and outputting;
Based on the synchronization signal, an OFDM frame configuration unit (14) that configures and outputs an OFDM frame from the transmission control signal group output from the signal level conversion unit and the signal for the central one segment, and
The signal level conversion unit (12) has one signal level of the two different signal levels equal to or higher than a first predetermined level, and a time average of the two different signal levels is equal to or lower than a second predetermined level. The transmission path coding apparatus is characterized in that the two different signal levels are determined.
(2) The first predetermined level is:
In a 13-segment assumed receiver that performs reception / presentation processing on the assumption that all 13-segment radio waves included in one frequency channel are received, reception / presentation processing of one-segment area broadcasting can be performed normally. A lower limit value of the signal level of the peripheral segment,
The second predetermined level is:
2. The transmission encoding apparatus according to claim 1, wherein the transmission encoding apparatus is an upper limit value of signal levels of peripheral segments, which is defined not to adversely affect another broadcast using a frequency band of a segment other than the central one segment. .
(3) A transmission path encoding method executed by a one-segment broadcasting transmission apparatus that uses only one central segment on the frequency axis among 13 segments included in one frequency channel,
A synchronization signal generation step of generating and outputting a synchronization signal that is a reference for the generation timing of the OFDM symbol;
Based on the synchronization signal, a transmission control signal group of a peripheral segment that is a segment other than the central one segment in the 13 segments to be broadcast is received as an input, and the signal level of the transmission control signal group is set to two different signals. A signal level conversion step for alternately converting to a level and outputting;
An OFDM frame configuration step of configuring and outputting an OFDM frame from the transmission control signal group output from the signal level conversion unit and the signal for the central one segment based on the synchronization signal;
In the signal level conversion step, one of the two different signal levels has a signal level equal to or higher than a first predetermined level, and a time average of the two different signal levels is equal to or lower than a second predetermined level. And determining the two different signal levels.

  According to the present invention, it is possible to cause a 13-segment assumed receiver to perform reception / presentation processing of a one-segment area broadcast more normally.

It is a block diagram of the transmission-line coding apparatus based on the Example of this invention. It is a schematic diagram (the 1) of a radio spectrum. It is a schematic diagram (the 2) of a radio spectrum. It is a schematic diagram (the 3) of a radio wave spectrum. It is a figure which shows the flow of a process of the signal level conversion part based on the Example of this invention.

[Example]
FIG. 1 is a diagram illustrating a configuration of a transmission path encoding apparatus 10 according to an embodiment of the present invention. The transmission path encoding apparatus 10 includes a synchronization signal generation unit 11, a signal level conversion unit 12, a transmission path encoding unit A13, an OFDM frame configuration unit 14, and a transmission path encoding unit B15.

  The synchronization signal generation unit 11 generates a synchronization signal that serves as a reference for OFDM symbol generation timing, and outputs the synchronization signal to the signal level conversion unit 12 and the OFDM frame configuration unit 14.

  The signal level conversion unit 12 stores two predetermined signal level conversion coefficients A and B, and based on the synchronization signal output from the synchronization signal generation unit 11, the stored signal level conversion coefficients A and B are stored. Read alternately. The signal level conversion unit 12 receives a transmission control signal for a peripheral segment, a pilot signal, and an additional signal (hereinafter referred to as a transmission control signal group) as inputs. Then, the signal level of the input transmission control signal group is converted based on the read signal level conversion coefficient A or B, and the converted transmission control signal group is output to the OFDM frame configuration unit 14.

  The transmission path encoding unit A13 receives as input the data for one-segment broadcasting transmitted in the central segment. The input data is subjected to various transmission path encoding processes (energy spreading, delay correction, convolutional encoding, subcarrier modulation, time interleaving, frequency interleaving, etc.), and the signals subjected to the various transmission path encoding processes are converted into OFDM frames. Output to the configuration unit 14. Here, the data for one-segment broadcasting is specifically a TS (Transport Stream) in which video and audio are multiplexed.

  The OFDM frame configuration unit 14 receives as input the signal output from the transmission path encoding unit A13, the transmission control signal group for the central segment, and the signal output from the signal level conversion unit 12. Then, each input signal is assigned to each subcarrier to form a block called an OFDM frame, which is output to the transmission path encoding unit B15. Note that signals other than the transmission control signal group for peripheral segments are not assigned to subcarriers (the signal level of the subcarriers is set to 0). The input signals are assigned to the subcarriers based on the synchronization signal from the synchronization signal generator 11.

  The transmission path encoding unit B15 receives the OFDM frame output from the OFDM frame configuration unit 14 as an input. Then, various transmission path encoding processes (fast inverse Fourier transform, guard interval addition, frequency conversion, etc.) are performed on the input OFDM frame, and an OFDM transmission signal is generated and output.

  Next, with reference to FIGS. 2 to 4, the spectrum of the radio wave broadcast by the one-seg type area broadcasting transmission device using the transmission path encoding device 10 will be described.

  Since one-segment area broadcasting uses only the central segment, it is ideal that no radio waves other than the central segment are transmitted. However, it is difficult with the current transmission technology. Therefore, it is important to suppress the signal level of radio waves other than the central segment to a signal level that does not adversely affect another broadcast using a frequency band other than the central segment. FIG. 2 is a diagram showing the upper limit value (EP1) of the signal level of the peripheral segment, which is defined not to adversely affect another broadcast using a frequency band other than the central segment. FIG. 2 shows only the frequency band of the central segment and its peripheral segments, which are necessary for the description of the present invention.

  On the other hand, in the 13-segment assumed receiver, the lower limit value (EP2) of the signal level of the peripheral segment that enables normal reception / presentation processing of the one-segment area broadcasting is higher than that of EP1 as shown in FIG. It is assumed that it is large. In this case, the 13-segment assumed receiver cannot normally perform the reception / presentation processing of the one-segment area broadcasting with respect to the radio wave of the one frequency channel shown in FIG.

  As described above, the signal level conversion unit 12 converts the signal level of the peripheral segment based on the conversion coefficient A or B. FIG. 4 is a diagram showing converted signal levels EPA and EPB. As shown in FIG. 4, the signal level conversion unit 12 converts the EPA so that it becomes EP2 or more and the time average (EPave) of EPA and EPB becomes EP1 or less.

  It is assumed that the 13-segment assumed receiver can perform reception / presentation processing normally even if the signal level of the peripheral segment does not exceed EP2 in time average, as long as the signal exceeds EP2 within a certain period. . In the transmission path encoding apparatus 10, for example, EP2 is exceeded within a certain period by changing the signal level of the radio wave every time one OFDM symbol is generated.

  Also, even if the radio wave temporarily exceeds EP1, if it does not exceed the time average of the signal level in a certain unit time or less, it may adversely affect another broadcast using a frequency band other than the central segment. It is assumed that there is no. In the transmission path encoding apparatus 10, the signal level of the radio wave is changed every time one OFDM symbol is generated as described above, so that the time average of the signal level within a certain unit time does not exceed EP1.

  Next, the outline of the processing flow of the transmission path encoding method will be described using the flowchart shown in FIG. First, the synchronization signal generator 11 generates a synchronization signal (step S1). Next, the signal level conversion unit 12 receives a transmission control signal group for peripheral segments as an input (step S2), selects one of the stored conversion coefficients A and B (step S3), and step The signal level of the transmission control signal group input in S2 is converted based on the conversion coefficient selected in Step S3 (Step S4). Next, the OFDM frame configuration unit 14 receives the transmission control signal group whose signal level has been converted in step S4, the data for the central segment, and the transmission control signal group for the central segment as inputs (step S5), and configures an OFDM frame. (Step S6). Steps S1 to S6 are repeated for each OFDM symbol generation timing. Each time steps S1 to S6 are repeated 204 times, one OFDM frame is completed.

  As described above, according to the one-segment area broadcasting transmission apparatus using the transmission path coding apparatus 10, the reception / presentation process of the one-segment area broadcasting is more normally performed even for the 13-segment assumed receiver. Therefore, it is possible to provide a transmission path encoding device and a transmission path encoding method.

  Some 13-segment receivers may not be able to perform reception / presentation processing normally if there is a large difference between EPA and EPB. In preparation for such a case, a condition that the difference between EPA and EPB is made as small as possible may be added to the signal level converter 12.

  In addition, some 13-segment receivers may not be able to perform reception / presentation processing normally when the signal level of the entire 13 segments changes. In preparation for such a case, for example, in the current OFDM symbol, the peripheral segment having an odd segment number is converted to an EPA signal level and has an even segment number in the current OFDM symbol. The peripheral segment converts the signal level of the EPB. In the next OFDM symbol, a peripheral segment having an odd segment number among peripheral segments is converted to an EPB signal level, and a signal level of EPA is converted to a peripheral segment having an even segment number. The two processes described above may be alternately switched based on the synchronization signal from the synchronization signal generator so that the total signal level in the entire 13 segments is always equal.

 In the description of the present embodiment, an example in which the signal level is converted into two signal levels is shown. However, the signal level can be converted into three or more signal levels.

  The present invention includes a program for causing a computer to realize the functions of the apparatus described above. These programs may be read from a recording medium and loaded into a computer, or may be transmitted via a communication network and loaded into a computer.

10: Transmission path encoder 11: Synchronization signal generator 12: Signal level converter 13: Transmission path encoder A
14: OFDM frame construction unit 15: Transmission path coding unit B

Claims (3)

A transmission path encoding apparatus used for a one-segment broadcasting transmission apparatus that uses only one central segment on the frequency axis among 13 segments included in one frequency channel,
A synchronization signal generation unit that generates and outputs a synchronization signal that is a reference for the generation timing of the OFDM symbol;
Based on the synchronization signal, a transmission control signal group of a peripheral segment that is a segment other than the central one segment in the 13 segments to be broadcast is received as an input, and the signal level of the transmission control signal group is set to two different signals. A signal level converter for alternately converting to a level and outputting,
An OFDM frame configuration unit configured to configure and output an OFDM frame from the transmission control signal group output from the signal level conversion unit and the central one-segment signal based on the synchronization signal;
The signal level conversion unit is configured so that one of the two different signal levels is equal to or higher than a first predetermined level, and a time average of the two different signal levels is equal to or lower than a second predetermined level. The transmission path coding apparatus, wherein the two different signal levels are determined. The first predetermined level is:
In a 13-segment assumed receiver that performs reception / presentation processing on the assumption that all 13-segment radio waves included in one frequency channel are received, reception / presentation processing of one-segment area broadcasting can be performed normally. A lower limit value of the signal level of the peripheral segment,
The second predetermined level is:
2. The transmission encoding apparatus according to claim 1, wherein the transmission encoding apparatus is an upper limit value of signal levels of peripheral segments, which is defined not to adversely affect another broadcast using a frequency band of a segment other than the central one segment. . A transmission path encoding method executed by a one-segment broadcasting transmission apparatus that uses only one central segment on the frequency axis among 13 segments included in one frequency channel,
A synchronization signal generation step of generating and outputting a synchronization signal that is a reference for the generation timing of the OFDM symbol;
Based on the synchronization signal, a transmission control signal group of a peripheral segment that is a segment other than the central one segment in the 13 segments to be broadcast is received as an input, and the signal level of the transmission control signal group is set to two different signals. A signal level conversion step for alternately converting to a level and outputting;
An OFDM frame configuration step of configuring and outputting an OFDM frame from the transmission control signal group output from the signal level conversion unit and the signal for the central one segment based on the synchronization signal;
The signal level converting step is such that one of the two different signal levels is equal to or higher than a first predetermined level, and a time average of the two different signal levels is equal to or lower than a second predetermined level. , And determining the two different signal levels.