JP2018029336A - OFDM transceiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an OFDM transmitter and an OFDM receiver which can increase the amount of transmission data of an A-class layer α while suppressing the decrease in the amount of transmission data of a B-class layer β.SOLUTION: In an OFDM transceiver, a power of a partial receiving part is amplified more than a power of a non-partial receiving part and is subjected to OFDM transmission. An OFDM transmitter is arranged to perform hierarchical transmission and comprises: a first carrier modifying part which carrier-modifies data of the partial receiving part; a second carrier modifying part which carrier-modifies data of the non-partial receiving part; hierarchical synthesizing part which synthesizes the carrier-modified partial receiving part data and non-partial receiving part data; a framing part which produces an OFDM frame; and an IFFT part which performs an IFFT process on the OFDM frame. The OFDM transmitter further comprises at least one of: an amplifying part which amplifies an output of the first carrier modifying part; and an attenuating part which attenuates an output of the second carrier modifying part.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an OFDM (Orthogonal Frequency Division Multiplexing) transmitter / receiver, and more particularly to an OFDM transmitter and OFDM receiver that perform hierarchical transmission.

  In current terrestrial television broadcasting in Japan, ISDB-T (Integrated Services Digital Broadcasting-Terrestrial) is used (Non-Patent Document 1). ISDB-T is a broadcasting system for terrestrial digital television broadcasting in which a frequency band (about 6 MHz) of one channel is divided into 13 bands (segments), and a transmission band is configured by these 13 OFDM segments.

  In the current terrestrial television broadcasting, hierarchical transmission is used, and a plurality of services with different image quality and noise resistance are provided in the same channel. Specifically, while providing a service (so-called one-segment broadcasting) for transmitting a strong noise-resistant video using one segment in the center of the transmission band as a partial receiving unit for a mobile receiving terminal (mobile terminal) Twelve segments are used for services (such as high-definition broadcasting) that transmit high-quality video for fixed receiving terminals (such as home televisions).

  In recent years, high-definition video called Super Hi-Vision (8K: 7680 pixels × 4320 lines) has been put into practical use, and a transmission system for next-generation terrestrial broadcasting corresponding to this has been studied.

  In next-generation terrestrial broadcasting, it is assumed that the OFDM signal having the segment structure of the current ISDB-T system will be maintained, and the transmission capacity and flexibility will be improved by expanding the signal bandwidth and the number of FFT points. ing. In addition, as a new technology, LDPC (Low Density Parity Check) code is used as an error correction code, non-uniform constellation is used as carrier modulation, SFN (single-frequency network) to which space-time coding is applied. ) Etc. are being studied.

  FIG. 7 shows main transmission parameters of provisional specifications for ISDB-T and next-generation terrestrial broadcasting. For example, the transmission bandwidth is increased by increasing the signal bandwidth from 5.57 MHz to 5.85 MHz and increasing the number of FFT points by 2 to 4 times. Further, by increasing the number of segments from 13 to 35, the bit rate of each layer can be finely adjusted, thereby improving flexibility.

  Hierarchical transmission is also planned for next-generation terrestrial broadcasting, and the number of segments for the partial reception unit for mobile reception terminals is inherited from the features of ISDB-T that can be received by a narrowband receiver. Improvement of mobile reception characteristics by adjusting the frequency and interleaving is being studied.

“Transmission system for digital terrestrial television broadcasting” standard, ARIB STD-B31, Japan Radio Industry Association

  FIG. 8 shows the structure of the frequency band of one channel assumed in next-generation terrestrial broadcasting. The entire transmission band is composed of a partial reception unit for mobile reception terminals (referred to as A layer in this specification, indicated by “α”), and a non-partial reception unit for fixed reception terminals (in this specification, B layer). It is indicated by “β”.) For example, the central 9 segments in the entire 35 segments are defined as “partial reception band (γ)”, and the A layer α is arranged in the partial reception band γ. A narrowband receiver such as a mobile reception terminal receives a signal in the partial reception band γ and demodulates only the A layer α. As shown in FIG. 8A, the maximum number of segments in layer A is 9 segments, which is the same as the partial reception band γ. If the A layer α is 3 segments, 9 segments of the partial reception band γ are configured together with 6 segments of the B layer β. As shown in FIG. 8 (B), frequency interleaving can be performed in segments within the partial reception band γ. When the A layer α is less than 9 segments, the A layers are arranged discretely across the layers. The segment α is processed.

  In terrestrial television broadcasting, it is required to improve reception characteristics of the partial receiver (A layer) as well as the non-partial receiver (B layer). In order to improve reception characteristics, it is desirable to increase the amount of transmission data.

  Assuming the channel configuration as shown in FIG. 8, as a means for increasing the transmission data amount of the A layer α, it is conceivable to increase the number of segments of the A layer α. However, since the total number of segments in the channel is fixed at 35, if the number of segments in layer A is increased, the number of segments in layer B is decreased and the amount of transmission data in layer B is decreased. Accordingly, there is a demand for means for increasing the transmission data amount of the A layer α and improving the reception characteristics of the A layer while suppressing the decrease in the transmission data amount of the B layer β.

  Accordingly, an object of the present invention made in view of the above problems is an OFDM transmitter capable of increasing the transmission data amount of the A layer α while suppressing the decrease of the transmission data amount of the B layer β. And providing an OFDM receiver.

  In order to solve the above problems, an OFDM transmission apparatus according to the present invention includes a first carrier modulation unit that performs carrier modulation on data of a partial reception unit, and a second carrier modulation unit that performs carrier modulation on data of a non-partial reception unit. A layer synthesizing unit that synthesizes carrier-modulated partial reception unit data and non-partial reception unit data, a framing unit that generates an OFDM frame, and an IFFT unit that performs IFFT processing on the OFDM frame, and performs hierarchical transmission. In the OFDM transmitter to perform, further comprising at least one of an amplifying unit for amplifying the output of the first carrier modulation unit and an attenuating unit for attenuating the output of the second carrier modulation unit, the power of the partial receiving unit Is characterized by transmitting an OFDM modulated signal larger than the power of the non-partial receiver.

  In addition, it is preferable that the OFDM transmitter adjusts the amplifying unit and the attenuating unit so that the total total power amount of the partial receiving unit and the non-partial receiving unit is constant.

  The OFDM transmission apparatus preferably includes an adjustment unit that amplifies the power of the pilot signal of the partial reception unit more than the power of the pilot signal of the non-partial reception unit.

  In the OFDM transmission apparatus, it is preferable that the OFDM modulation signal includes a TMCC signal describing an amount of power amplification of the partial reception unit or an amount of power attenuation of the non-partial reception unit.

  In the OFDM transmitter, it is preferable that the amplifying unit amplifies the partial receiver based on the TMCC up to 8 dB at a maximum as compared with a case where the entire frequency band is a uniform power.

  In the OFDM transmission apparatus, it is preferable that the adjustment unit amplifies the pilot signal power of the partial reception unit based on the TMCC up to 8 dB at a maximum compared to when the entire frequency band is a uniform power. .

  In addition, it is preferable that the OFDM transmitter transmits an OFDM modulated signal in which the power of the partial receiver is larger than the power of the non-partial receiver from a plurality of antennas.

  In order to solve the above problems, an OFDM receiving apparatus according to the present invention includes an FFT unit that performs an FFT process on a received signal in an OFDM receiving apparatus that receives an OFDM modulated signal in which the power of a partial receiving unit is greater than the power of a non-partial receiving unit. A deframe unit that extracts a data signal from the FFT-processed signal, a layer separation unit that separates the extracted data signal into a partial reception unit and a non-partial reception unit, and a carrier demodulation of data in the partial reception unit It includes at least one of a first carrier demodulator and a second carrier demodulator that performs carrier demodulation on the data of the non-partial receiver.

  The OFDM receiver includes an extraction unit that extracts a pilot signal, a transmission path estimation unit that estimates a transmission path using a pilot signal of a partial reception unit and an amplified pilot signal of a non-partial reception unit, It is desirable to further include an equalization unit that corrects the signal based on the channel coefficient estimated by the transmission path estimation unit.

  According to the OFDM transmitting apparatus and OFDM receiving apparatus of the present invention, it is possible to increase the transmission data amount of the A layer α while suppressing the decrease of the transmission data amount of the B layer β.

It is a figure explaining the relationship between the segment of a transmission system utilized by this invention, and electric power. It is an example of the block diagram of the OFDM transmitter of embodiment. It is an example of the block diagram of the OFDM receiver of embodiment. It is a graph which shows the relationship of the attenuation amount of B layer with respect to the amplification amount of A layer. It is a graph which shows the relationship between required C / N of A hierarchy (3 segments), and a transmission rate. It is a graph which shows the relationship between required C / N of B hierarchy, and a transmission rate. It is a figure which shows the comparison of the main transmission parameters of the provisional specification of ISDB-T and next generation terrestrial broadcasting. It is a figure which shows the structure of the frequency band of 1 channel assumed by next-generation terrestrial broadcasting.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment)
FIG. 1 is a diagram for explaining the relationship between power transmission segments and power used in the present invention. In the present invention, in order to improve the reception characteristics of A layer α, which is a partial receiver, and to increase the transmission capacity, the power of the segment of A layer α is amplified, and the power of the partial receiver (A layer α) is non-partial received. An OFDM modulated signal larger than the power of the part (B layer β) is used. FIG. 1A is an example of a spectrum (no frequency interleaving process) when the three segments of the A layer α are amplified, and is compared with a case where the amplification is not performed (FIG. 1B).

In this example, the transmission power within the 6 MHz band is considered to be kept constant, and the case where all segments are transmitted with uniform power (FIG. 1B) is used as a reference for the three segments of the A layer α. The power is amplified by P _{1, and} the power of 32 segments in the B layer β is attenuated by P ₂ . Therefore, (number of segments in layer A) × P ₁ is approximately equal to (number of segments in layer B) × P ₂ .

  When there is no condition for keeping the transmission power in the 6 MHz band constant, the power of the three segments of the A layer α can be amplified as much as necessary without performing the power attenuation of the B layer β.

  As will be described later, by amplifying the power of the segment of the A layer α, the required C / N (Carrier to Noise ratio) of the A layer α is improved and the transmission rate can be increased. Further, as the transmission power increases, the area in which the signal of the layer A can be transmitted is expanded.

FIG. 1C is a diagram illustrating an example of a pilot signal when a segment of layer A is amplified more than layer B β. At this time, the pilot signal SP ₁ of the A layer α has a higher power than the pilot signal SP ₂ of the B layer β. The power of the pilot signal SP ₁ of the A layer α is changed to the power of the B layer β at the same ratio (for example, [1 + k] times) that the power of the data signal of the A layer α is larger than the power of the data signal of the B layer β. it is desirable to amplification than the power of the pilot signal SP _2. Note that it is desirable that the power of the partial receiver (A layer α signal and pilot signal SP ₁ ) is amplified to 8 dB at the maximum as compared with the case where the entire frequency band is uniform power. This is because the amount of power attenuation of the non-partial reception unit (B layer β signal and pilot signal SP ₂ ) is suppressed to 3 dB at the maximum by boosting the partial reception unit up to 8 dB. is there. At this time, the amplification degree [k] of the power of the partial receiver with respect to the power of the non-partial receiver is 11 dB at the maximum. As will be described later, when the required C / N of the A layer is improved by the power boost, and the number of segments used in the A layer is increased, the modulation multi-level number and the coding rate of the A layer are made highly resistant, and the required C / N When the power boost of the A layer is up to 8 dB, the improvement of the required C / N of the A layer by the power boost reduces the amount of C / N degradation of the B layer and the power boost. The benefits of boosting are great.

  This pilot signal amplification can be applied to both an SP (Scattered Pilot) signal and a CP (Continual Pilot) signal. Although not shown in the figure, it is desirable that the power of the TMCC signal of the A layer α is amplified more than the power of the TMCC signal of the B layer β similarly for a TMCC (Transmission and Multiplexing Configuration and Control) signal. In the figure, one pilot signal is illustrated for each segment. However, a necessary number of pilot signals and TMCC signals may be inserted in a predetermined arrangement in a frame as in the case of a normal OFDM signal.

  In addition, although it demonstrated based on the spectrum of 35 segments which is the provisional specification of next-generation terrestrial broadcasting here, increasing the electric power of the segment of a partial receiver part more than the electric power of the segment of a non-partial receiver part is the present. A 13-segment transmission method is also applicable. That is, it is possible to amplify the power of one segment (partial reception unit) in the center of the transmission band more than the other 12 segments and improve the reception characteristics of the one-segment service.

  Here, the transmission apparatus will be described. FIG. 2 is an example of a block diagram of an OFDM transmitter that performs power amplification of layer A data.

  An OFDM transmission apparatus 10 according to an embodiment of the present invention includes a carrier modulation unit 11, an amplification unit 12, an attenuation unit 13, a layer synthesis unit 14, a framing unit 15, an adjustment unit 16, and an IFFT (Inverse Fast Fourier Transform) unit 17. A transmission unit 18 and an antenna 19. The OFDM transmitter 10 can transmit the data “a” of the A layer and the data “b” of the B layer with different power amounts of the respective segments.

  The carrier modulation unit 11 outputs a carrier symbol by performing mapping processing of input data according to a preset parameter and modulation scheme. Here, the description of processing such as energy spreading, interleaving, and error correction coding performed in normal OFDM modulation is omitted, but can be performed as necessary. The carrier modulation unit (first carrier modulation unit) 11 a is a carrier modulation unit that modulates data of the A layer, and outputs the modulated signal to the amplification unit 12. Further, the carrier modulation unit (second carrier modulation unit) 11 b is a carrier modulation unit that modulates data of the B layer, and outputs the modulated signal to the attenuation unit 13. In general, the modulation method for the data of the B layer used for fixed reception is a modulation method having a larger modulation multi-value number and a larger data transmission amount than that of the A layer.

  The amplification unit 12 receives the modulation signal from the carrier modulation unit 11a and amplifies the power of the modulated signal of the A layer data a based on a preset amplification amount. Then, the amplifying unit 12 outputs the amplified modulation signal of the A layer to the layer synthesizing unit 14.

  The attenuator 13 receives the modulation signal from the carrier modulator 11b, and attenuates the power of the modulated signal of the B layer data b based on a preset attenuation amount. Then, the attenuating unit 13 outputs the attenuated B-layer modulation signal to the layer synthesizing unit 14.

  As described above, when there is no condition for keeping the transmission power in the 6 MHz band constant, it is not necessary to provide the attenuation unit 13. If the output power of the carrier modulation units 11a and 11b is set to one output power (power attenuated or amplified more than usual) in advance, only one of the amplification unit 12 and the attenuation unit 13 can be provided. That's fine. It is desirable that the amplifying unit 12 be configured to amplify the power of the A layer data a (partial receiving unit) up to 8 dB as compared with the case where the entire frequency band is set to a uniform power. Further, it is desirable that the attenuating unit 13 is configured to be able to suppress the attenuation amount of the power of the B layer data b (non-partial receiving unit) to 3 dB at the maximum as compared with the case where the power attenuation is uniform in all frequency bands. .

  The layer synthesizing unit 14 receives the amplified A layer modulated data (carrier symbol) after amplification from the amplifying unit 12 and the attenuated B layer modulated data (carrier symbol) from the attenuating unit 12, and has completed the A layer modulation. The data and B-layer modulated data are hierarchically combined. Then, the data signals of the A layer and the B layer after the layer synthesis are output to the framing unit 15.

  The framing unit 15 receives the layer A and B layer data signals after the layer synthesis from the layer synthesis unit 14, the input layer A and B layer data signals, and the pilot signal input from the adjustment unit 16. An OFDM frame is generated by arranging TMCC signals and the like (not shown) at predetermined carriers and symbol positions. The framing unit 15 outputs the modulated signal converted into an OFDM frame to the IFFT unit 17.

The adjustment unit 16 adjusts the power of the pilot signal. That is, as shown in FIG. 1C, the pilot signal (SP signal, CP signal) arranged in the segment of layer A α is amplified, and the power of the pilot signal arranged in the segment of layer B β is changed to B. Adjust according to the data symbol of layer β. And outputs a (pilot signal SP ₂ of the pilot signal SP _1, B hierarchy β of A hierarchical alpha) pilot signal to adjust the power to the framing unit 15. Although not shown, the adjustment unit 16 may adjust the power of the TMCC signal in the same manner as the pilot signal. The TMCC signal generally describes transmission parameters such as the modulation scheme, the number of segments, and the coding rate. In the present invention, in addition to these parameters, the amplification amount of the amplifier 12 (the power of the partial receiver) And the attenuation amount of the attenuating unit 13 (attenuation amount of power of the non-partial receiving unit) are desirably described in the TMCC signal. The adjustment unit 16 can amplify the power of the pilot signal (partial reception unit) arranged in the segment of the A layer α based on the TMCC signal to 8 dB at the maximum as compared with the case where the entire frequency band is a uniform power. Further, the power attenuation amount of the pilot signal (non-partial receiver) arranged in the segment of the B layer β is configured to be suppressed to 3 dB at the maximum as compared with the case where the entire frequency band is set to be uniform power. It is desirable.

  The IFFT unit 17 receives the modulated signal converted into an OFDM frame from the framing unit 15 and performs IFFT processing on the modulated signal to convert the frequency domain signal into a time domain signal. Then, IFFT unit 17 outputs the modulated signal converted into the time domain signal to transmitting unit 18.

  The transmitter 18 receives the modulated signal converted into the time domain signal from the IFFT unit 17 and performs processing necessary to transmit the modulated signal. For example, a guard interval is added to the OFDM signal, orthogonal modulation is performed, frequency conversion is performed to a radio frequency signal, power amplification is performed, and a transmission signal is output from the antenna 19.

  Thereby, the transmission apparatus 10 transmits the OFDM modulation signal from which the power of the segment of the A layer shown in FIGS. 1A and 1C is amplified from the antenna 19.

  Next, the receiving apparatus will be described. FIG. 3 is an example of a block diagram of an OFDM transmission apparatus that receives a signal obtained by power-amplifying layer A data.

  An OFDM receiver 20 according to an embodiment of the present invention includes an antenna 21, a receiving unit 22, an FFT (Fast Fourier Transform) unit 23, an SP extraction unit 24, a transmission path estimation unit 25, an equalization unit 26, and a deframe unit. 27, a layer division unit 28, and a carrier demodulation unit 29.

  The OFDM signal received by the antenna 21 and having the power amplified from the A layer data is input to the receiving unit 22. The receiving unit 21 converts the radio frequency received signal into an intermediate frequency signal, performs quadrature demodulation, performs signal processing necessary for subsequent FFT processing, such as removal of guard intervals, and the like to the FFT unit 23. Output.

  The FFT unit 23 performs FFT processing on the signal processed by the receiving unit 22 and converts the time domain signal into a frequency domain signal. Then, the FFT unit 23 outputs the signal converted into the frequency domain to the SP extraction unit 24 and the equalization unit 26.

The SP extraction unit 24 extracts a pilot signal (particularly, an SP signal) from the signal converted into the frequency domain from the FFT unit 23 and outputs the extracted pilot signal to the transmission path estimation unit 25. Even if this SP extraction unit 24 is a receiving device that acquires data of the A layer, the non-partial reception unit (B) in the vicinity of the partial reception unit together with the pilot signal (SP ₁ ) of the partial reception unit (A layer α). A part of the pilot signal (SP ₂ ) of the layer β) is also extracted. As will be described later, the accuracy of channel estimation can be improved by using the pilot signal of the non-partial receiver. Since it is obvious that a TMCC signal is extracted from the signal subjected to the FFT processing by the FFT unit 23 and information necessary for demodulation is obtained, it is not shown here.

The transmission path estimation unit 25 estimates a transmission path based on the pilot signal from the SP extraction unit 24. During channel estimation utilizes both pilot signals (SP ₂₎ of the pilot signals (SP ₁₎ and the non-partial reception portion of the partial reception portion (A hierarchy alpha) (B hierarchy beta). Here, as shown in FIG. 1C, the pilot signals of the partial receiving unit α and the non-partial receiving unit β are extracted at a ratio corresponding to the power ratio at the time of transmission because the power at the time of transmission is different. The pilot signal of the received non-partial receiver (B layer β) is amplified (for example, the SP ₂ signal is corrected by [1 + k] times), and then calculation processing is performed to calculate the channel coefficient H of each transmission path . Even reception device for obtaining data for the A-layer, the partial reception portion with pilot signals (A hierarchy α) (SP _1), a part of the pilot signal of the non-partial reception portion (B hierarchy β) (SP ₂₎ By amplifying and using (the pilot signal of the non-partial reception unit in the vicinity of the partial reception unit), it becomes possible to estimate the transmission path with higher accuracy. Thereafter, the transmission path estimation unit 25 outputs the channel coefficient H of each transmission path to the equalization unit 26. The reception apparatus to obtain data for B hierarchy utilize all partial reception portion of the pilot signals (SP ₁₎ and the non-partial reception portion of (A hierarchy alpha) pilot signal (B hierarchy β) (SP ₂₎ be able to.

  The equalization unit 26 performs equalization processing based on the signal y input from the FFT unit 23 and the channel coefficient H input from the transmission path estimation unit 25. That is, each signal y is corrected (y / H) by the respective channel coefficient H, a corrected OFDM frame is calculated, and output to the deframing unit 27.

  The deframe unit 27 extracts a necessary data signal (data symbol) from the signal of the OFDM frame from the equalization unit 26. The deframing unit 27 outputs the extracted data signal to the hierarchy dividing unit 28.

  The layer division unit 28 receives the data signal (data symbol) from the deframe unit 27, divides it into data of each layer (here, data of layer A and data of layer B), and carrier demodulation To the unit 29.

  The carrier demodulator (first carrier demodulator) 29a is a carrier demodulator that demodulates A layer data, and the carrier demodulator (second carrier demodulator) 29b is a carrier demodulator that demodulates B layer data. Part. Here, both carrier demodulation units 29a and 29b are described. However, when the data processed by the receiving apparatus is one of the A layer and the B layer, the demodulation unit selects one according to the data to be processed. It only has to have. The carrier demodulator 29 demaps the data symbols, further performs deinterleaving processing and error correction decoding (not shown), and outputs data a or b of each layer.

  Thereby, the receiving apparatus 20 receives the OFDM modulation signal in which the power of the segment of the A layer shown in FIG. 1A is amplified, and outputs the data a or b for each layer.

  So far, both the transmission apparatus and the reception apparatus have been described with respect to a single antenna SISO (single input and single output) transmission method. However, the OFDM modulated signal amplified by the partial reception unit of the present invention is transmitted between the transmission apparatus and the reception apparatus. Both MIMO (multiple-input and multiple-output) using a plurality of antennas, and MISO (multiple-input and single-output) transmission method using a plurality of antennas for the transmitting device and one antenna for the receiving device. Available.

  At this time, the transmission apparatus transmits an OFDM modulated signal in which the power of the partial receiver shown in FIGS. 1A and 1C is larger than the power of the non-partial receiver from the plurality of antennas. In addition, the reception apparatus receives the OFDM modulated signal amplified by the partial reception unit transmitted from the plurality of antennas, using a plurality of antennas or one antenna. As a result, the reception characteristics of the partial reception unit (A layer) are further improved.

(Verification of effect)
The effects of the present invention will be verified below. Here, a comparison was made between the case where the power of the segment transmitting the data of the A layer is amplified and the case where the number of segments transmitting the data of the A layer is increased.

  FIG. 4 shows the power attenuation amount of the B layer when the power of the A layer is amplified under the condition that the total number of segments is 35 and the total transmission power is constant. In FIG. 4, the numbers in the parentheses after the graph numbers 41 to 45 describe the number of segments in the A layer and the number of segments in the B layer in a ratio format. For example, the graph 41 shows the relationship between the power amplification amount of the A layer and the power attenuation amount of the B layer in the case where the A layer is 1 segment and the B layer is 34 segments, and the graph 45 is a case where the A layer is 9 segments. The relationship between the power amplification amount of the A layer and the power attenuation amount of the B layer when the B layer is 26 segments is shown.

  Here, when the A layer is 3 segments and the B layer is 32 segments, the graph 42 corresponds, and it can be seen that if the A layer is amplified by 5 dB, the B layer attenuates by 1 dB. Although it is theoretically possible to increase the amplification amount of the A layer to 10 dB, in order to secure the number of segments of the A layer (for example, 3 segments) and to suppress the attenuation amount of the B layer to 3 dB at the maximum, It is desirable that the power of the A layer is amplified to a maximum of 8 dB than when the entire frequency band is uniform power.

  Next, consider the case where the A layer is amplified by 5 dB. FIG. 5 shows the relationship between the required C / N of layer A and the transmission rate of 3 segments by combining carrier modulation (QPSK, 16QAM, 64QAM) and error correction coding rate (5/15 to 13/15) in layer A. It is shown. Assuming a QPSK (Quadrature Phase Shift Keying) / coding rate of 12/15 as a normal carrier modulation and coding rate, the required C / N is 5.2 dB, and the transmission rate is 0.67 Mbps. When the power of the A layer is amplified by 5 dB, reception at the same reception point is possible with a combination of carrier modulation and coding rate with a required C / N of 10.2 dB. Therefore, 16QAM (Quadrature Amplitude Modulation) / coding rate 11 / Fifteen transmission schemes are available. At this time, the transmission rate is 1.24 Mbps, which increases 1.9 times. This is a transmission rate obtained by increasing the number of segments of layer A from 3 segments to 5.7 (= 3 × 1.9) segments (about 6 segments) when carrier modulation QPSK and coding rate 12/15 are not used for power amplification. Is the same.

  Here, in order to increase the transmission rate of the A layer, the case where the A layer 3 segment is amplified by 5 dB (the B layer is 32 segments) and the case where the A layer is increased from 3 segments to 6 segments without power amplification (B Consider the effect of 29 segments) on the B layer. FIG. 6 shows the relationship between the required C / N and the transmission rate of 32 segments and 29 segments in the B layer. Focusing on 256QAM / coding rate 12/15, in the graph of B layer 32 segments (A layer 3 segments), the required C / N is 22 dB, and the transmission rate is 28.7 Mbps. When the A layer is amplified by 5 dB, the B layer is attenuated by 1 dB from FIG. 4 (graph 42), and the C / N at the same reception point is 21 dB. Therefore, the transmission rate of the B layer is 27.2 Mbps, which is about 95% before the attenuation. Decrease. On the other hand, if the A layer is increased from 3 segments to 6 segments, the B layer has no power attenuation but decreases from 32 segments to 29 segments. Therefore, as shown in the graph of the B layer 29 segments, the required C / N is 22 dB. The transmission rate is 26.0 Mbps and is reduced to about 91%. Therefore, in order to expand the transmission capacity of the A layer, the influence on the B layer is less when the power of the A layer is amplified than by increasing the number of segments of the A layer.

  As described above, from the result of comparing the transmission rates of the B layer when the power of the A layer is amplified and the number of segments is increased without power amplification of the A layer, the power of the A layer is amplified according to the present invention. It has been confirmed by an example that the reduction in the transmission rate of the B layer can be reduced in the case of the above. Note that, by amplifying the power of the A layer of the present invention, the effect of reducing the decrease in the transmission rate of the B layer can be reduced as compared with the case where the number of segments is increased without amplifying the power of the A layer. A higher effect is produced in the range up to 8 dB than when (amplification) is set to uniform power in the entire frequency band.

  Although the above embodiment has been described as a representative example, it will be apparent to those skilled in the art that many changes and substitutions can be made within the spirit and scope of the invention. Therefore, the present invention should not be construed as being limited by the above-described embodiments, and various modifications and changes can be made without departing from the scope of the claims. For example, a plurality of constituent blocks described in the embodiments can be combined into one, or one constituent block can be divided.

DESCRIPTION OF SYMBOLS 10 OFDM transmission apparatus 11 Carrier modulation part 12 Amplification part 13 Attenuation part 14 Hierarchy synthesis part 15 Framing part 16 Adjustment part 17 IFFT part 18 Transmission part 19 Antenna 20 OFDM receiver 21 Antenna 22 Reception part 23 FFT part 24 SP extraction part 25 Transmission path estimation unit 26 Equalization unit 27 Deframement unit 28 Hierarchy separation unit 29 Carrier demodulation units 41 to 45 Graph

Claims (9)

A first carrier modulation unit for carrier modulating the data of the partial reception unit;
A second carrier modulation unit for carrier modulating the data of the non-partial reception unit;
A layer synthesizing unit that synthesizes the data of the carrier-modulated partial receiving unit and the data of the non-partial receiving unit;
A framing unit for generating an OFDM frame;
In an OFDM transmission apparatus that includes an IFFT unit that performs an IFFT process on an OFDM frame and performs hierarchical transmission,
Furthermore, it comprises at least one of an amplifying unit for amplifying the output of the first carrier modulating unit and an attenuating unit for attenuating the output of the second carrier modulating unit, and the power of the partial receiving unit is that of the non-partial receiving unit. An OFDM transmitter that transmits an OFDM-modulated signal larger than power.   2. The OFDM transmitter according to claim 1, wherein the amplifying unit and the attenuating unit are adjusted so that a total total power amount of the partial receiving unit and the non-partial receiving unit is constant. .   3. The OFDM transmission apparatus according to claim 1, further comprising: an adjustment unit that amplifies the pilot signal power of the partial reception unit more than the pilot signal power of the non-partial reception unit.   4. The OFDM transmission apparatus according to claim 1, wherein the OFDM modulation signal is a TMCC signal describing a power amplification amount of the partial reception unit or a power attenuation amount of the non-partial reception unit. 5. An OFDM transmitter characterized by comprising.   5. The OFDM transmitter according to claim 4, wherein the amplifying unit amplifies the power of the partial receiver based on the TMCC up to 8 dB as compared with a case where the entire frequency band is a uniform power. .   5. The OFDM transmitter according to claim 4, wherein the adjustment unit amplifies the pilot signal power of the partial reception unit up to 8 dB based on the TMCC as compared with a case where the entire frequency band is a uniform power. OFDM transmitter.   The OFDM transmission apparatus according to any one of claims 1 to 6, wherein the OFDM transmission apparatus transmits, from a plurality of antennas, an OFDM modulated signal in which power of a partial reception unit is larger than that of a non-partial reception unit. In an OFDM receiver that receives an OFDM modulated signal in which the power of the partial receiver is larger than the power of the non-partial receiver,
An FFT unit for FFT processing the received signal;
A deframe unit for extracting a data signal from the FFT-processed signal;
A layer separation unit that separates the extracted data signal into a partial reception unit and a non-partial reception unit;
An OFDM receiving apparatus comprising at least one of a first carrier demodulating unit for carrier demodulating data of a partial receiving unit and a second carrier demodulating unit for carrier demodulating data of a non-partial receiving unit.   9. The OFDM receiver according to claim 8, wherein an extraction unit that extracts a pilot signal, and a transmission path estimation unit that estimates a transmission path using a pilot signal of a partial reception unit and an amplified pilot signal of a non-partial reception unit And an equalizer for correcting a signal based on the channel coefficient estimated by the transmission path estimation unit.

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