JP6909015B2 - Transmitter and receiver - Google Patents

Description

The present invention relates to a transmitting device and a receiving device that transmit a signal of 64APSK (Amplitude and Phase Shift Keying) coding modulation via a non-linear transmission line.

In recent years, there has been an increasing demand for transmission of high bit rates such as 4K / 8K ultra-high-definition video, and there is a demand for expansion of transmission capacity. One of the approaches to increase the transmission capacity is to expand the multi-value number of the multi-value modulation method, but in a modulation method with a high multi-value number such as 64APSK, it is easily affected by noise and a high required C / N is required. It becomes. In particular, in a nonlinear transmission line, a modulated signal having a higher number of values is more susceptible to nonlinear distortion, which causes deterioration of transmission performance.

Multiplex transmission of transmission signal point arrangement signals (hereinafter, also referred to as "pilot signals") adopted in the transmission method (ISDB-S3) of advanced broadband satellite digital broadcasting as a conventional technique for improving the influence of nonlinear distortion in a satellite transmission line. Techniques are known (see, for example, Non-Patent Document 1).

"Transmission method for advanced wideband satellite digital broadcasting (ISDB-S3) Standard ARIB STD-B44 2.1 version", Association of Radio Industries and Businesses (ARIB), revised on March 25, 2016

As described above, a technique for multiplex transmission of pilot signals adopted in the transmission method (ISDB-S3) for high-wideband satellite digital broadcasting is known.

However, in ISDB-S3, the maximum number of modulation multi-values applicable as coded modulation is 32, and therefore, a pilot signal is input to each modulation slot constituting the frame of the modulation wave multiplex-transmitted in ISDB-S3. As the transmission area of, only 32 symbols defined as the maximum number of modulation multi-values are secured.

Therefore, even if the ISDB-S3 tries to transmit the 64APSK coded modulation data from the transmitting device to the receiving device, the 64APSK pilot signal is not transmitted, so that the non-linear distortion in the satellite transmission line is generated. As a result, there arises a problem that sufficient transmission performance cannot be obtained.

In view of the above problems, the present invention is desired to adapt the 64APSK coded modulation data to ISDB-S3 when transmitted via the satellite transmission line, and to improve the influence of nonlinear distortion in the satellite transmission line. It is an object of the present invention to provide a transmitting device and a receiving device capable of ensuring the transmission performance of the above.

The transmission device of the present invention is a transmission device that transmits a coded modulation signal via a non-linear transmission path, and generates a transmission main signal obtained by subjecting the data of the main signal to be transmitted to 64 APSK coded modulation processing. The transmission main signal generation means and the pilot signal indicating the signal point arrangement information of 64APSK are divided into the first half 32 symbols and the second half 32 symbols in a known order between transmission and reception in ascending or descending order of symbols, and energy diffusion processing is performed respectively. For the modulation slot that can store the transmission pilot signal of up to 32 symbols for each transmission pilot signal of the first half 32 symbols and the second half 32 symbols , the first half 32 symbols are assigned to the odd modulation slot, and the second half 32 symbols are assigned to the odd modulation slot. Pilot signal multiplexing means for time-dividing multiplexing of the odd-modulated slot and the even-modulated slot to which the transmission main signal is assigned by allocating to the even-modulated slot located next to the slot, and advanced broadband satellite digital broadcasting. A pilot having a transmission means for transmitting the transmission main signal and a pilot signal indicating the signal point arrangement information of the 64APSK with a modulated wave having a multiple frame structure defined by the transmission method, and showing the signal point arrangement information of the 64APSK. In the signal, the 6-bit first bit constituting the 64APSK symbol is "a1", the second bit is "a2", the third bit is "a3", the fourth bit is "a4", and the fifth bit is "a4". "A5", the 6th bit is "a6", the 6 bits are expressed in octal notation as "octane notation", the signal point indicating the first half 32 symbols is expressed as "first half", and the latter half 32 symbols. The signal points indicating the above are represented as "second half", and for each signal point in the pilot signal, the coordinate points on the orthogonal coordinates representing the in-phase component and the orthogonal component are designated as "I" and "Q", respectively, and the phase on the orthogonal coordinates. When the amount of rotation is "phase (deg)", it is characterized by having Table 1 shown below.

Further, the receiving device of the present invention receives the transmission pilot signal of 64APSK divided into two into the first half 32 symbols and the second half 32 symbols transmitted from the transmitting device of the present invention, performs energy reverse diffusion processing, and performs the energy back diffusion processing. It is characterized in that the signal point arrangement of the pilot signal is restored and averaged according to the known order, and the phase error table used as the reference coordinate at the time of carrier reproduction is updated by using the averaged symbol. ..

Further, the receiving device of the present invention receives the transmission pilot signal of 64APSK divided into two into the first half 32 symbols and the second half 32 symbols transmitted from the transmitting device of the present invention, performs energy reverse diffusion processing, and performs the energy back diffusion process. It is characterized in that the signal point arrangement of the pilot signal is restored and averaged according to a known order, and the likelihood table at the time of LDPC decoding is updated by using the averaged symbol.

According to the present invention, 64APSK coded modulation data is adapted to ISDB-S3 when transmitted via a satellite transmission line, and the influence of nonlinear distortion in the satellite transmission line is improved to ensure desired transmission performance. can do.

It is a block diagram which shows the schematic structure of the transmission device of one Embodiment by this invention. It is a block diagram which shows the schematic structure of the receiving device of one Embodiment by this invention. It is a block diagram which shows the schematic structure of the orthogonal detection part in the receiving device of one Embodiment by this invention. It is a block diagram which shows the schematic structure of the LDPC decoding unit in the receiving apparatus of one Embodiment by this invention. It is a figure which shows the signal point arrangement and bit allocation of 64APSK coding modulation of one Example which concerns on the transmitting device and the receiving device of one Embodiment by this invention. It is a figure which shows the frame structure of the 64APSK coded modulation of one Example which concerns on the transmitting device and the receiving device of one Embodiment by this invention. (A) is a simulation of a transmission signal point when 64APSK coded modulation data is transmitted in the absence of a pilot signal according to the transmission device and the reception device of one embodiment according to the present invention and a reception signal point after passing through a non-linear transmission line. The constellation showing the result, (b) is the average after passing through the non-linear transmission line when the data of 64APSK coded modulation is transmitted in the presence of the pilot signal related to the transmitting device and the receiving device of one embodiment according to the present invention. This is a constellation showing the simulation results of the pilot signal point after the conversion and the received signal point after passing through the non-linear transmission line. Transmission performance when 64APSK coded modulation data is transmitted for a state without a pilot signal (pilot signal OFF) and a state with a pilot signal (pilot signal ON) related to the transmitting device and the receiving device of one embodiment according to the present invention. It is a figure which shows the comparison.

Hereinafter, the transmitting device 10 and the receiving device 20 according to the embodiment of the present invention will be described with reference to the drawings.

[Transmission device]
FIG. 1 is a block diagram showing a schematic configuration of a transmission device 10 according to an embodiment of the present invention. The transmission device 10 is configured in the same manner as the transmission method (ISDB-S3) for advanced broadband satellite digital broadcasting as a schematic configuration thereof, but performs 64APSK data transmission according to a predetermined signal point arrangement and bit allocation. The difference is that the pilot signal corresponding to the signal point arrangement of the 64APSK is configured to be capable of multiplex transmission. More specifically, the transmission device 10 of the embodiment according to the present invention shown in FIG. 1 is further provided with a pilot signal distribution unit 17 in order to multiplex transmit the pilot signal corresponding to the signal point arrangement of 64APSK. In that respect, it differs from the transmitter specified in ISDB-S3.

That is, in ISDB-S3, as the modulation method, π / 2 shift BPSK (1 bit / symbol), QPSK (2 bits / symbol), 8PSK (3 bits / symbol), 16APSK (or 16QAM, 4 bits / symbol), And 32APSK (or 32QAM, 5 bits / symbol) are specified, but in the transmission device 10 according to the present invention, in addition to this, 64APSK (or 64QAM, 6 bits / symbol) data transmission as a modulation method and its addition are performed. The pilot signal is configured to be multiplex transmitted in conformity with the frame configuration of ISDB-S3.

The transmission device 10 includes a frame generation unit 11, a BCH coding unit 12, an energy diffusion unit 13, an LDPC coding unit 14, a bit interleaver 15, an orthogonal modulation / time division multiplexing unit 16, a TMCC signal generation unit 11a, and a BCH coding. A unit 12a, an energy diffusion unit 13a, an LDPC coding unit 14a, an energy diffusion unit 13b, and a pilot signal distribution unit 17 are provided.

The frame generation unit 11 includes control information, external code parity in which control information and data (main signal) are encoded by BCH coding unit 12, staff bits, and control information, data, and outside by LDPC coding unit 14. A frame consisting of slots # 1 to # 120 for configuring the code parity and the staff bit with the LDPC-encoded internal code parity is generated. The slot length is 44,880 bits.

The BCH coding unit 12 performs external code coding processing on the control information and data (main signal) in each slot in one frame by BCH code according to the modulation method / coding rate information to generate external code parity. Then, it is added to the control information and data (main signal).

The energy diffusion unit 13 performs energy diffusion processing (bit randomization) on the control information, data, external code parity, and stuff bits in each slot in one frame. This is realized by generating pseudo-random "1" and "0" patterns using the M sequence, and adding MOD2 to this and the data in the slot.

The LDPC coding unit 14 performs internal code coding processing on the control information, data, external code parity and stuff bits after energy diffusion processing in each slot by LDPC code to generate internal code parity, and after energy diffusion processing. It is added to the control information, data, external code parity and stuff bit.

In ISDB-3, the bit interleaver 15 has a modulation method of 8PSK and 16APSK.
In the case of 32APSK and 32APSK, bit interleaving is performed within the one frame, and the same bit interleaving is performed for 64APSK according to the present invention.
As a result, the transmission main signal of each modulation method is formed via the LDPC coding unit 14 or the bit interleaver 15.

The TMCC signal generation unit 11a generates a TMCC signal for storing transmission control information (TMCC information) that describes the modulation method / coding rate information related to the data transmission of the main signal, and outputs the TMCC signal to the BCH coding unit 12a.

The BCH coding unit 12a performs an external code coding process on the TMCC signal with a BCH code to generate and add an external code parity.

The energy diffusion unit 13a performs energy diffusion processing (bit randomization) on the TMCC signal and the external code parity.

The LDPC coding unit 14a performs an internal code coding process on the TMCC signal and the external code parity after the energy diffusion process by the LDPC code to generate and add the internal code parity.
As a result, the transmission TMCC signal is formed via the LDPC coding unit 14a.

The energy diffusion unit 13b performs energy diffusion processing on a pilot signal indicating signal point arrangement information according to the modulation method of each slot to generate a transmission pilot signal.

Although details will be described later, in ISDB-S3, the pilot signals of π / 2 shift BPSK, QPSK, 8PSK, 16APSK, and 32APSK have the number of symbols (32 symbols) that can be accommodated in one slot. The 64APSK pilot signal according to the above does not fit in one slot.

Therefore, the transmission device 10 according to the present invention is provided with a pilot signal distribution unit 17 for multiplex transmission of the pilot signal of 64APSK. The transmission device 10 according to the present invention is configured to transmit the pilot signal of 64APSK in two divisions, and in order to improve the processing efficiency on the receiving side, the ascending order of the symbols constituting the signal point arrangement of 64APSK. It is configured to transmit (or in descending order).
More specifically, first, the energy diffusion unit 13b performs energy diffusion processing on the first half 32 symbols in the ascending order (or descending order) of the symbols in the pilot signal of 64APSK, and inputs the energy diffusion unit 17 to the pilot signal distribution unit 17. The pilot signal distribution unit 17 quadraturely modulates the energy diffusion processed first half 32 symbols 64APSK pilot signal so as to allocate it to an odd modulation slot (modulation slots # 1, # 3, ... # 119) as a transmission pilot signal. / Output to the time division multiplexing unit 16.

Similarly, the energy diffusion unit 13b performs energy diffusion processing on the latter 32 symbols in the ascending order (or descending order) of the symbols in the pilot signal of 64APSK, and inputs the energy diffusion unit to the pilot signal distribution unit 17. The pilot signal distribution unit 17 quadraturely modulates the energy diffusion processed 64APSK pilot signal of the latter 32 symbols so as to be assigned to even modulation slots (modulation slots # 2, # 4, ... # 120) as transmission pilot signals. / Output to the time division multiplexing unit 16.
Therefore, for the 64APSK pilot signal, the first 32 symbols are periodically assigned to the odd modulation slots and the second 32 symbols are periodically assigned to the even modulation slots in ascending (or descending) order of the symbols.

As a result, the processing itself for the 64APSK pilot signal in the energy diffusion unit 13b can be performed in the same manner as other modulation methods, so that the processing load on the receiving side does not deteriorate.

The orthogonal modulation / time division multiplexing unit 16 uses π / 2 shift BPSK modulation, QPSK modulation, 8PSK modulation, 16APSK modulation, 32APSK modulation, or 64APSK modulation for the transmission main signal and transmission pilot signal, and sets the transmission TMCC signal and frame synchronization signal. And the slot synchronization signal is time-divided and multiplexed as π / 2 shift BPSK modulation, and a modulated wave of 120 modulation slots is generated per multiplex frame and output to the outside. Since this modulated wave is transmitted to the receiving side via the satellite transmission line, it is affected by its non-linear distortion.

[Receiver]
FIG. 2 is a block diagram showing a schematic configuration of a receiving device 20 according to an embodiment of the present invention. Further, FIG. 3 is a block diagram showing a schematic configuration of the orthogonal detection unit 22 in the receiving device 20, and FIG. 4 is a block diagram showing a schematic configuration of the LDPC decoding unit 24 in the receiving device 20.

The receiving device 20 is configured in the same manner as the transmission method (ISDB-S3) for advanced broadband satellite digital broadcasting as a schematic configuration thereof, but has 64 APSK signal points transmitted according to a predetermined signal point arrangement and bit allocation. The difference is that the pilot signal corresponding to the arrangement is received, and the 64APSK data transmitted from the transmission device 10 is demodulated / decoded based on the signal point of the received pilot signal so that the data can be received. is doing.

The receiving device 20 includes a channel selection unit 21, an orthogonal detection unit 22, a TMCC decoding unit 23, an LDPC decoding unit 24, an energy reverse diffusion unit 25, and a BCH decoding unit 26.

The channel selection unit 21 receives a modulated wave transmitted from the transmission device 10 via the satellite transmission path via a predetermined satellite broadcasting antenna, and receives a frequency conversion unit built in the satellite broadcasting antenna (FIG. 6). A BS-IF signal (first intermediate frequency signal) is input via (not shown), a channel is selected, and the signal of that channel is the second intermediate frequency signal of each of the in-phase component (I) and the orthogonal component (Q). Is converted to and output to the orthogonal detection unit 22.

The orthogonal detection unit 22 synchronously detects the second intermediate frequency signal (baseband signal) of the signal point (I signal and Q signal) detected in a state where complete synchronous detection is not performed, and the signal point (I signal and I signal). It is converted into a synchronous baseband signal of (Q signal) and output to the LDPC decoding unit 24.

The TMCC decoding unit 23 inputs a synchronous baseband signal obtained from the orthogonal detection unit 22, first detects a synchronous byte of the TMCC signal from the synchronous baseband signal, and periodically multiplexes the BPSK with reference to the synchronous byte. The position of the phase reference burst signal, which is a modulated wave, is also detected and demodulated. Subsequently, the TMCC decoding unit 23 performs a predetermined likelihood determination, decodes the LDPC-encoded TMCC signal by the LDPC coding unit 14a on the transmitting side, and reverse-spreads the energy corresponding to the energy spreading unit 13a on the transmitting side. The processing is performed, and the BCH code decoding processing corresponding to the BCH coding unit 12a on the transmitting side is performed to extract the TMCC information.

The TMCC decoding unit 23 generates a modulation method / coding rate selection signal to be described later based on the extracted TMCC information, detects a transmission pilot signal from the orthogonal detection output of the orthogonal detection unit 22, and detects the transmission pilot signal of the transmission pilot signal. A timing pulse is generated and output to the orthogonal detection unit 22 and the LDPC decoding unit 24. Further, based on the extracted TMCC information, the TMCC decoding unit 23 converts each diffusion code corresponding to the energy diffusion unit 13 and the energy diffusion unit 13b on the transmission side into the energy reverse diffusion unit 25, the orthogonal detection unit 22, and the LDPC decoding unit, respectively. Output to 24.

The LDPC decoding unit 24 performs a predetermined likelihood determination described later, decodes the data related to the LDPC-encoded main signal by the LDPC coding unit 14 on the transmitting side, and outputs the data to the energy reverse diffusion unit 25. When the modulation method related to the main signal is 8PSK, 16APSK, 32APSK, and 64APSK according to the present invention, bit deinterleaving corresponding to the bit interleaver 15 on the transmitting side is performed at the input stage of the LDPC decoding unit 24. ..

The energy reverse diffusion unit 25 performs energy reverse diffusion processing corresponding to the energy diffusion unit 13 on the transmitting side on the data related to the main signal output from the LDPC decoding unit 24, and outputs the data to the BCH decoding unit 26.

The BCH decoding unit 26 performs BCH code decoding processing corresponding to the BCH coding unit 12 on the transmitting side on the data related to the main signal subjected to the energy back diffusion processing, restores the data of the main signal, and outputs the data to the outside. ..

The pilot signal corresponding to the signal point arrangement of 64APSK transmitted according to the signal point arrangement and the bit allocation specified in advance is used by the orthogonal detection unit 22 and the LDPC decoding unit 24 as described below.

(Orthogonal detector)
As shown in FIG. 3, the orthogonal detection unit 22 includes a complex multiplication unit 221, a root roll-off filter (RRF) 222-1,222-2, a transmission pilot signal extraction unit 223, an energy back diffusion unit 224, and a pilot signal averaging. It includes a unit 225, a phase error table generation unit 226, a phase error table storage unit 227, a loop filter (LF) 228, and a numerically controlled oscillator (NCO) 229.

The complex multiplication unit 221 sets the second intermediate frequency signal of the detected signal point (I signal and Q signal) in a state where the perfect synchronous detection is not performed, so that the I signal and the Q signal become a stationary signal point. A numerically controlled oscillator (NCO) 229 inputs a signal whose phase error has been corrected based on the pilot signal described later, performs complex multiplication, and routes the I signal and Q signal, which are stationary signal points, to the root roll-off filter (RRF), respectively. Output to 222-1,222-2.

The root roll-off filter (RRF) 222-1,222-2 frequency-limits the I signal and the Q signal obtained from the complex multiplication unit 221 and uses the I signal and the Q signal obtained thereby as the orthogonal detection output as a phase error table. Output to the storage unit 227 and the LDPC decoding unit 24.

Since the phase error table storage unit 227 controls the frequency in the complex multiplication unit 221, the orthogonal detection output from the root roll-off filter (RRF) 222-1,222-2 is input, and the received signal point and the ideal signal point. Refer to the held phase error table for obtaining the phase difference from the reference signal point corrected according to the pilot signal from the signal point, and the phase of the signal point of the orthogonal detection output and the reference signal point according to the pilot signal. A comparison is performed, and a value proportional to the amount of the phase error is output to the loop filter (LF) 228.

The phase error table is updated and generated by signal point arrangement information (pilot signal) affected by transmission path distortion obtained based on a transmission pilot signal described later.

The loop filter (LF) 228 performs a smoothing process on a value proportional to the amount of phase error obtained from the phase error table storage unit 227 and outputs the value to the numerically controlled oscillator (NCO) 229.

The Numerically Controlled Oscillator (NCO) 229 sets a value proportional to the amount of phase error smoothed by the loop filter (LF) 228, and generates a phase error-corrected signal based on the pilot signal to generate a complex. Output to the multiplication unit 221.

The transmission pilot signal extraction unit 223 extracts a part of the transmission pilot signal from the output of the route roll-off filter 222-1,222-2 by using the timing pulse of the pilot signal obtained from the TMCC decoding unit 23, and reverses the energy. Output to the diffuser 224.

The energy reverse diffusion unit 224 performs energy reverse diffusion processing corresponding to the energy diffusion unit 13b on the transmission side on the transmission pilot signal extracted by the transmission pilot signal extraction unit 223, and outputs the transmission pilot signal to the pilot signal averaging unit 225. The diffusion code of this energy reverse diffusion process is obtained from the TMCC No. decoding unit 23 (not shown).

The pilot signal averaging unit 225 accumulates the signal points of the pilot signals that are periodically transmitted for each symbol of the pilot signal obtained by performing the energy back diffusion processing, and the signal point positions on the IQ plane thereof. The average value of is obtained, and the value is output to the phase error table generation unit 226. In the case of the 64APSK pilot signal according to the present invention, the first 32 symbols are in the odd modulation slot in the order of "000000", "000001", "0000010" ... "011111", and the latter 32 symbols are "1000000" "100001". Since the signals are transmitted in the even modulation slots in the order of "100010" ... "111111", the pilot signal averaging unit 225 integrates the signal points of the pilot signals transmitted periodically for each symbol. Find the average value.

The phase error table generation unit 226 generates a phase error table using the average value of the signal point positions on the IQ plane of the pilot signal obtained from the pilot signal averaging unit 225, and outputs the phase error table to the phase error table storage unit 227. To update and retain. That is, the signal points whose average value of the signal point positions of each symbol is on the same circumference are extracted, summarized for each circumference radius, and the phase error table is generated in that.

In this way, the phase error table generation unit 226 updates the phase error table held by the phase error table storage unit 227 based on the pilot signal, so that the phase error table is transmitted due to aging of the satellite repeater or change of the backoff amount. Even if the path characteristics change, the receiving device 2 follows the changes and can always perform optimum phase error detection, enabling stable synchronous detection in which cycle slip is unlikely to occur.

(LDPC decoding unit)
On the other hand, as shown in FIG. 4, the LDPC decoding unit 24 includes an LDPC code decoding unit 241, a transmission pilot signal extraction unit 242, an energy reverse diffusion unit 243, a pilot signal averaging unit 244, a likelihood table generation unit 245, and a likelihood. A degree table storage unit 246 is provided.

The LDPC code decoder 241 refers to the likelihood table specified by the modulation method / code rate selection signal input from the TMCC decoding unit 23 among the likelihood tables held in the likelihood table storage unit 246. The LDPC code is decoded and output to the energy reverse diffusion unit 25.

The likelihood table further includes a log-likelihood ratio (1) from the posterior probability that 0 was transmitted and the posterior probability that 1 was transmitted to a certain received signal point of each modulation method according to the LDPC coding rate. LLR: Log-Lilelihood Ratio) is shown.

Then, each likelihood table held in the likelihood table storage unit 246 is updated by the likelihood table generation unit 245, which will be described later, based on the pilot signal, and the satellite repeater changes over time and backs up. Even if the transmission line characteristics change due to a change in the off amount or the like, the receiving device 20 follows the changes and can always perform optimum code decoding, and the required C / N can be reduced.

The transmission pilot signal extraction unit 242 uses the timing pulse of the pilot signal obtained from the TMCC decoding unit 23 to extract the transmission pilot signal portion from the output of the route roll-off filter 222-1,222-2 in the orthogonal detection unit 22. It is extracted and output to the energy reverse diffusion unit 243.

The energy reverse diffusion unit 243 performs energy reverse diffusion processing corresponding to the energy diffusion unit 13b on the transmission side on the transmission pilot signal extracted by the transmission pilot signal extraction unit 242, and outputs the transmission pilot signal to the pilot signal averaging unit 244. The diffusion code of this energy reverse diffusion process is obtained from the TMCC No. decoding unit 23 (not shown).

The pilot signal averaging unit 244 accumulates the signal points of the pilot signals that are periodically transmitted for each symbol of the pilot signal obtained by performing the energy back diffusion processing, and the signal point positions on the IQ plane thereof. The average value of is obtained, and the value is output to the phase error table generation unit 245. In the case of the 64APSK pilot signal according to the present invention, the first 32 symbols are in the odd modulation slot in the order of "000000", "000001", "0000010" ... "011111", and the latter 32 symbols are "1000000" "100001". Since the signals are transmitted in the even modulation slots in the order of "100010" ... "111111", the pilot signal averaging unit 225 integrates the signal points of the pilot signals transmitted periodically for each symbol. Find the average value.

The likelihood table generation unit 245 generates a likelihood table using the average value of the signal point positions on the IQ plane of the pilot signal obtained from the pilot signal averaging unit 244, and outputs the likelihood table to the likelihood table storage unit 246. To update and retain.

The likelihood table storage unit 246 holds a likelihood table according to the LDPC coding rate of each modulation method in the modulation method / coding rate selection signal generated by the likelihood table generation unit 245.

Hereinafter, more specifically, the transmitting device 10 and the receiving device 20 according to the present invention will be described in detail, focusing on the 64APSK signal point arrangement and bit allocation according to the present invention and the pilot signal corresponding to the 64APSK signal point arrangement. explain.

First, the transmitting device 10 and the receiving device 20 according to the present invention are configured to improve the transmission performance of 64APSK coded modulation affected by non-linear distortion in the satellite transmission line.

Non-linear transmission lines of satellite repeaters cause non-linear distortion in the amplitude and phase directions. In particular, in a multi-valued APSK such as 64APSK, the signal points on the outer circumference are subject to amplitude suppression and phase rotation. Therefore, on the receiving device 20 side, the carrier reproduction and LDPC decoding are affected by the non-linear distortion, and the transmission performance is deteriorated. Therefore, on the receiving device 20 side, deterioration due to non-linear distortion is suppressed and transmission performance is improved by using a pilot signal in each process of carrier reproduction and LDPC decoding.

(Career regeneration)
Carrier regeneration is performed by the orthogonal detection unit 22 shown in FIG. As described above, the orthogonal detection unit 22 outputs a synchronous baseband signal by orthogonally detecting the received signal using the same carrier as the transmitting side generated by the baseband IQ signal and the phase error table.

At this time, if the phase error table used for carrier reproduction is set to the ideal signal point arrangement at the time of transmission of the transmission device 10, the detection accuracy of the phase error decreases, and the transmission performance deteriorates due to an increase in the cycle slip probability and a decrease in the synchronization accuracy. .. This is because while the received signal has amplitude suppression and phase rotation due to nonlinear distortion, a phase error table is generated based on the ideal signal point arrangement at the time of transmission that is not affected by nonlinear distortion, and carrier reproduction is performed. Because it is.

(LDPC decoding)
The LDPC decoding is performed by the LDPC decoding unit 24 shown in FIG. As described above, the LDPC decoding unit 24 performs LDPC decoding using the likelihood table.

At this time, since the signal for LDPC decoding is a signal affected by non-linear distortion, LDPC decoding is performed using the likelihood table obtained by using the ideal signal point arrangement at the time of transmission of the transmission device 10 as the reference coordinates. Good transmission performance cannot be obtained. This is because the received signal is subjected to non-linear distortion in the amplitude and phase directions due to the influence of the non-linear characteristics, whereas the generation of the likelihood table applied to LDPC decoding is not affected by the non-linear distortion, which is an ideal signal at the time of transmission. This is because the point arrangement is used as the reference coordinate.

Therefore, the transmitting device 10 and the receiving device 20 according to the present invention are configured to transmit a pilot signal of 64APSK coding modulation in order to improve the performance against these non-linear distortions.

In the case of the 64APSK pilot signal according to the present invention, the transmission device 10 is placed in the odd modulation slot in the ascending order in this example, with the first 32 symbols in the order of "000000", "000001", "0000010" ... "011111". The latter 32 symbols are transmitted in the even modulation slots in the order of "100,000", "100001", "100010" ... "111111".

The receiving device 20 receives the pilot signal affected by the non-linear distortion, but since the transmission order of the symbols at the time of transmission is defined as described above, even the pilot signal affected by the non-linear distortion is known. The signal point arrangement and bit allocation can be correctly obtained according to the mapping order. When the ideal signal point arrangement at the time of transmission of the transmission device 10 is used as the reference coordinates by obtaining the phase error table at the time of carrier reproduction and the likelihood table at the time of LDPC decoding with the pilot signal subjected to this non-linear distortion as the reference coordinates. It is possible to perform carrier regeneration and likelihood calculation with higher accuracy.

As a result, it is possible to improve the deterioration of transmission performance due to the non-linear characteristics of the 64APSK signal transmission. Further, even when the receiving device 10 receives the 64APSK pilot signal whose symbol is divided into two, it can be restored by a simple bit increment (or bit decrement), so that the processing efficiency can be improved.

(Example)
In the example described below, the transmission performance is evaluated by computer simulation using a nonlinear transmission line model that simulates the characteristics of a 12 GHz band satellite repeater as its nonlinear characteristics. The effect of distortion due to non-linear characteristics changes depending on the backoff value of the satellite repeater, but here the backoff value was set to 5.0 dB for evaluation.

FIG. 5 is a diagram showing signal point arrangement and bit allocation of 64APSK-coded modulation of one embodiment according to the transmitting device 10 and the receiving device 20 of the embodiment according to the present invention. Further, the transmission symbol order of the pilot signals transmitted corresponding to the signal point arrangement of the 64APSK coding modulation shown in FIG. 5 is as shown in Table 1 described above. Regarding FIG. 5, as shown in association with Table 1, the 6 bits assigned to the signal points are the first bit (a1), the second bit (a2), ..., The sixth bit (a6) from the left. In octal notation (example: 26 = 010: 110).

Regarding Table 1, the transmission performance affects not only the presence / absence of transmission of the pilot signal but also the signal point arrangement and bit allocation of 64APSK coding modulation, but here, the evaluation mainly based on the presence / absence of transmission of the pilot signal will be described.

By the way, in ISDB-S3, the maximum number of modulation multi-values applicable as coded modulation is 32, and therefore, a pilot signal is input to each modulation slot constituting the frame of the modulation wave multiplex transmitted by ISDB-S3. As the transmission area of, only 32 symbols defined as the maximum number of modulation multi-values are secured.

Therefore, even if the ISDB-S3 tries to transmit the 64APSK coded modulation data from the transmitting device to the receiving device, the 64APSK pilot signal is not transmitted, so that the non-linear distortion in the satellite transmission line is generated. As a result, there arises a problem that sufficient transmission performance cannot be obtained.

Therefore, as shown in FIG. 6, the structure of the multiple frames in the transmission device 10 and the reception device 20 according to the present invention is the structure of the multiple frames composed of 120 modulation slots in order to correspond to ISDB-S3, and 64 APSK. In order to enable transmission of the pilot signal, the first 32 symbols of the 64APSK pilot signal are transmitted in ascending order to the odd modulation slot, and the latter 32 symbols are transmitted in ascending order to the even modulation slot. In addition, instead of ascending order, descending order may be used.

As described above, the receiving device 20 receives the pilot signal during carrier reproduction and LDPC decoding, averages the received pilot signal, and removes noise after being affected by the non-linear characteristics of the transmission line. You can know the signal point arrangement of.

Then, the receiving device 20 suppresses the cycle slip probability, improves the carrier synchronization accuracy, and improves the deterioration of the transmission performance due to the non-linear distortion by using this signal point arrangement as the reference coordinate for generating the phase error table at the time of carrier reproduction. It becomes possible to do.

Further, the receiving device 20 can generate a likelihood table in consideration of the influence of non-linear distortion by using this signal point arrangement also for generating the likelihood table at the time of LDPC decoding.

As a result, it is possible to improve the deterioration of the transmission performance due to the non-linear characteristics at the time of 64APSK coding modulation while complying with the configuration defined in the current ISDB-S3.

FIG. 7A shows the transmission signal point when the 64APSK coded modulation data is transmitted in the absence of the pilot signal according to the transmission device 10 and the reception device 20 of the embodiment according to the present invention, and after passing through the non-linear transmission path. This is a constellation showing the simulation result of the received signal point. Further, FIG. 7B shows averaging after passing through the non-linear transmission line when the 64APSK coded modulation data is transmitted in the presence of the pilot signal according to the transmitting device 10 and the receiving device 20 of the embodiment according to the present invention. This is a constellation showing the simulation results of the later pilot signal point and the received signal point after passing through the non-linear transmission line.

With reference to FIG. 7A, it can be seen that the received signal after passing through the non-linear transmission line is affected by the non-linear distortion, and the signal points are suppressed inward by the outer peripheral circle, and the signal points are phase-rotated. Therefore, the center of each received signal is deviated from the signal point arrangement of the transmitted signal shown in the figure. Therefore, even if the ideal signal point arrangement at the time of transmission is used as the reference coordinate as it is and the likelihood table for LDPC decoding is obtained, good decoding characteristics cannot be obtained.

On the other hand, referring to FIG. 7B, it can be seen that the averaged pilot signal is arranged substantially in the center of the received signal. By updating the likelihood table with the pilot signal subjected to the non-linear distortion as the reference coordinates, it is possible to obtain good LDPC decoding characteristics in consideration of the non-linear distortion.

FIG. 8 shows 64APSK coding modulation according to FIG. 5 with respect to a state without a pilot signal (pilot signal OFF) and a state with a pilot signal (pilot signal ON) according to the transmission device 10 and the reception device 20 according to the present invention. It is a figure which shows the comparison of the transmission performance at the time of transmitting the data of. In FIG. 8, the LDPC coding rate of the 64APSK coded modulation signal is set to 4/5.

From FIG. 8, it can be seen that the transmission performance can be improved by about 0.53 dB by generating the likelihood table of LDPC decoding in consideration of the non-linear distortion from the pilot signal.

The present invention is not limited to the examples of the above-described embodiments, but is limited only by the description of the scope of claims. For example, in the example of the above-described embodiment, only the evaluation result of the transmission performance for a specific LDPC coding rate 4/5 has been described, but the performance of other LDPC coding rates 4/5 should be improved in the same manner. Is possible.

According to the present invention, 64APSK coded modulation data is adapted to ISDB-S3 when transmitted via a satellite transmission line, and the influence of nonlinear distortion in the satellite transmission line is improved to ensure desired transmission performance. Therefore, it is useful for applications of a transmitting device and a receiving device that transmit a signal of 64APSK coding modulation via a non-linear transmission line.

10 Transmitter 11 Frame generator 12 BCH coding section 13 Energy diffusion section 14 LDPC coding section 15-bit interleaver 16 Orthogonal modulation / time division multiplexing section 17 Pilot signal distribution section 11a TMCC signal generation section 12a BCH coding section 13a Energy Diffusing part 14a LDPC coding part 13b Energy spreading part 20 Receiver 21 Channel selection part 22 Orthogonal detection part 23 TMCC decoding part 24 LDPC decoding part 25 Energy despreading part 26 BCH decoding part 221 Complex multiplication part 222-1,222-2 Root roll-off filter (RRF)
223 Transmission pilot signal extraction unit 224 Energy reverse diffusion unit 225 Pilot signal averaging unit 226 Phase error table generation unit 227 Phase error table storage unit 228 Loop filter (LF)
229 Numerically Controlled Oscillator (NCO)
241 LDPC code decoder 242 Transmission pilot signal extraction unit 243 Energy reverse diffusion unit 244 Pilot signal averaging unit 245 Likelihood table generation unit 246 Likelihood table storage unit

Claims (3)

A transmitter that transmits a coded modulation signal via a non-linear transmission line.
A transmission main signal generation means for generating a transmission main signal obtained by subjecting the data of the main signal to be transmitted to 64 APSK coding modulation processing, and
The pilot signal indicating the signal point arrangement information of 64APSK is divided into the first half 32 symbols and the second half 32 symbols in a known order between transmission and reception in ascending or descending order of symbols, and the first half 32 symbols and energy diffusion processing are applied respectively. For the modulation slot that can store the transmission pilot signal of up to 32 symbols for each transmission pilot signal of the latter 32 symbols , the first half 32 symbols are assigned to the odd modulation slot, and the latter 32 symbols are assigned to the even number located next to the odd modulation slot. Pilot signal multiplexing means for time-dividing and multiplexing the odd modulation slot and the even modulation slot to which the transmission main signal is assigned periodically so as to be assigned to the modulation slot.
It is a modulated wave having a multiple frame structure defined by a transmission method for advanced broadband satellite digital broadcasting, and includes a transmission means for transmitting the transmission main signal and a pilot signal indicating signal point arrangement information of the 64APSK.
The pilot signal indicating the signal point arrangement information of 64APSK is
The 6-bit first bit constituting the 64APSK symbol is "a1", the second bit is "a2", the third bit is "a3", the fourth bit is "a4", and the fifth bit is "a5". The 6th bit is "a6", the 6 bits are expressed in octal notation as "octal notation", the signal point indicating the first half 32 symbols is expressed as "first half", and the signal indicating the second half 32 symbols. The points are represented as "second half", and for each signal point in the pilot signal, the coordinate points on the orthogonal coordinates representing the in-phase component and the orthogonal component are designated as "I" and "Q", respectively, and the phase rotation amount on the orthogonal coordinates is defined as "I" and "Q", respectively. When it is set to "phase (deg)"

A transmitter characterized by consisting of. The transmission pilot signal of 64APSK divided into the first half 32 symbols and the second half 32 symbols transmitted from the transmission device according to claim 1 is received, energy reverse diffusion processing is performed, and the transmission and reception are performed according to a known order. A receiving device comprising a means for restoring a signal point arrangement of a pilot signal, averaging it, and updating a phase error table as a reference coordinate at the time of carrier reproduction using the averaged symbol. The transmission pilot signal of 64APSK divided into two into the first half 32 symbols and the second half 32 symbols transmitted from the transmission device according to claim 1 is received, energy reverse diffusion processing is performed, and the transmission and reception are performed according to a known order. A receiving device comprising a means for restoring and averaging the signal point arrangement of a pilot signal and updating the likelihood table at the time of LDPC decoding using the averaged symbol.

Images