CN113411279A

CN113411279A - Reusable Q power demapping method and system based on DVB-S2 system

Info

Publication number: CN113411279A
Application number: CN202110550435.3A
Authority: CN
Inventors: 胡婉如; 王竹刚; 梅如如; 陈轩
Original assignee: National Space Science Center of CAS
Current assignee: National Space Science Center of CAS
Priority date: 2021-05-20
Filing date: 2021-05-20
Publication date: 2021-09-17
Anticipated expiration: 2041-05-20
Also published as: CN113411279B

Abstract

The invention discloses a method and a system for de-mapping a reusable Q power based on a DVB-S2 system, wherein the method comprises the following steps: receiving a signal and a modulation mode signal of a DVB-S2 system, determining the modulation type of the received signal according to the modulation mode signal, performing corresponding Q power operation on the received signal after QPD algorithm phase offset compensation, then performing power detection, and judging a ring where a symbol is located according to the relation between a power detection value and a power judgment threshold; and performing demapping on the received signal according to the received signal, the signal after Q power operation and the ring where the decision symbol is located to obtain a corresponding constellation point bit. Under different modulation modes, the error code performance of the algorithm is superior to that of a demapping algorithm based on amplitude and phase and a demapping algorithm based on amplitude; the resource consumption is lower than that of other geometric algorithms; and the method has reusability, can reduce DSP resource consumption after multiplexing, and can be better applied to a DVB-S2 system.

Description

Reusable Q power demapping method and system based on DVB-S2 system

Technical Field

The invention relates to the technical field of digital signal processing, in particular to a method and a system for de-mapping a reusable Q power based on a DVB-S2 system.

Background

With the further increase of information transmission demand, the data transmission rate is further improved, the spatial channel spectrum resources are increasingly strained, and the problems of bandwidth increase and low transmission efficiency caused by using QPSK (Quadrature Phase Shift Keying, QPSK is the most common satellite digital signal modulation method) are increasingly prominent. Therefore, in the inter-satellite link design, saving the space channel spectrum resource is the primary problem. In the whole working process of the data transmission link, along with the increase of the elevation angle of the antenna, the communication distance is shortened, the transmission loss of a channel is reduced, and the adoption of a Constant Coding and Modulation (CCM) technology can cause great waste of link gain. Therefore, in order to fully utilize the inter-satellite link resources, a new generation of digital satellite broadcasting standard, DVB-S2, is proposed. In the DVB-S2 standard, two working modes, namely Variable Coding and Modulation (VCM) and Adaptive Coding and Modulation (ACM), are proposed, wherein a VCM (Variable Coding and Modulation) technology can switch between multiple Modulation modes according to inter-satellite link gain conditions, so as to fully utilize link resources and greatly improve data transmission capacity. The modulation modes that can be supported by the DVB-S2 standard VCM mode are QPSK, 8PSK (8 Phase Shift Keying), 16APSK (16 Amplitude Phase Shift Keying), and 32APSK (32 Amplitude Phase Shift Keying).

In the DVB-S2 receiver, after the signal is synchronized, demapping judgment is needed, and demapping algorithms are divided into hard judgment and soft judgment according to different processing modes of received code elements. In the prior art, the traditional logarithmic representation method has higher complexity and is difficult to realize when the M-APSK is high; the soft demapping algorithm based on the hard decision threshold is high in calculation complexity and lacks hardware platform verification; the gray mark PSK modulation soft demapping algorithm is only suitable for M-PSK modulation; the high-order QAM modulation soft demapping algorithm is simplified, the calculation complexity is reduced, and the decoding convergence speed is reduced. In order to reduce the computational complexity of the communication system, a hard decision demapping algorithm is generally adopted. The DF-PSP demapping algorithm is suitable for a high-order modulated Pair PCMA (Carrier Multiple Access) communication system. The de-mapping algorithm based on the amplitude and the phase has relatively long simulation time and high calculation complexity; the proposed amplitude-based demapping algorithm is not suitable for 32APSK modulation and the error performance is degraded.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a method and a system for de-mapping a reusable Q power based on a DVB-S2 system.

In order to achieve the above object, the present invention provides a method for demultiplexing Q-power reusable based on DVB-S2 system, the method comprising:

receiving a signal and a modulation mode signal of a DVB-S2 system, determining the modulation type of the received signal according to the modulation mode signal, performing corresponding Q power operation on the received signal after QPD algorithm phase offset compensation, then performing power detection, and judging a ring where a symbol is located according to the relation between a power detection value and a power judgment threshold; and performing demapping on the received signal according to the received signal, the signal subjected to Q power operation and a ring where the decision symbol is located to obtain a corresponding constellation point bit, wherein Q is an integer greater than or equal to 0, and the Q power operation is Q power operation and corresponding phase rotation.

As an improvement of the above method, the determining a modulation type of the received signal according to the modulation mode signal specifically includes:

and determining the modulation type of the received signal according to the modulation mode signal mode:

when mode is 0, the received signal is QPSK modulated;

when the mode is 1, the received signal is 8PSK modulation;

when mode is 2, the received signal is 16APSK modulation;

when mode is 3, the received signal is 32APSK modulated.

As an improvement of the above method, the received signals are each represented by the following formula:

q_k＝(Re_k+j*Im_k)

wherein, Re_k，Im_kRespectively representing the received signal q at time k_kReal and imaginary parts of (c).

As an improvement of the above method, when the received signal is a QPSK modulated signal, the method specifically includes:

when the received signal is a QPSK modulation signal, Q is 0, and the angle β of phase rotation is 0;

demapping the received signal after QPD algorithm phase offset compensation to obtain the bit b of the corresponding constellation point from high to low₁b₀Satisfies the following formula:

when Re_kWhen b is greater than or equal to 0, b ₁0, otherwise, b₁＝1；

When Im is_kWhen b is greater than or equal to 0, b ₀0, otherwise, b₀＝1。

As an improvement of the above method, when the received signal is an 8PSK modulated signal, the method specifically includes:

when the received signal is 8PSK modulated signal, Q is 2, the phase is rotated by an angle

Performing power of 2 operation on the signal q (k) after QPD algorithm phase deviation compensation and

obtaining a signal z (k);

carrying out power detection on the signal z (k) to obtain a signal power detection value P (k), and judging that the symbols are on the circle;

based on the received signal q (k), a power of 2 operation and

the phase-rotated signal z (k) of (a) is demapped to obtain the bits b from high to low of the corresponding constellation point₂b₁b₀Satisfies the following formula:

(Re_k ²≥0)&(Im_k ²≥0)&(Re_k≥0)

b₂b₁b₀＝001；

(Re_k ²≥0)&(Im_k ²≥0)&(Re_k<0)

b₂b₁b₀＝010；

(Re_k ²<0)&(Im_k ²≥0)&(Re_k≥0)

b₂b₁b₀＝000；

(Re_k ²<0)&(Im_k ²≥0)&(Re_k<0)

b₂b₁b₀＝011；

(Re_k ²<0)&(Im_k ²<0)&(Im_k≥0)

b₂b₁b₀＝100；

(Re_k ²<0)&(Im_k ²<0)&(Im_k<0)

b₂b₁b₀＝111；

(Re_k ²≥0)&(Im_k ²<0)&(Im_k≥0)

b₂b₁b₀＝110；

(Re_k ²≥0)&(Im_k ²<0)&(Im_k<0)

b₂b₁b₀＝101

wherein, Re_k ²,Im_k ²Representing the real and imaginary parts of the signal z (k), respectively; "&"means the logical operator" AND ", i.e., satisfied simultaneously.

As an improvement of the above method, when the received signal is a 16APSK modulated signal, the method specifically includes:

when the received signal is a 16APSK modulated signal, Q is 3, and the angle β of phase rotation is 0;

performing power operation of 3 and phase rotation of 0 on the signal q (k) after the QPD algorithm phase offset compensation to obtain a signal z (k);

carrying out power detection on a signal z (k) to obtain a signal power detection value P (k), wherein a power judgment threshold value is T, and when P (k) is more than or equal to T, a ring where a judgment symbol is located is an excircle; when P (k) < T, the ring where the decision symbol is located is an inner circle;

de-mapping the received signal according to the received signal, the signal after 3 power operation and 0 phase rotation and the ring where the decision symbol is located to obtain the bit b of the corresponding constellation point from high to low₃b₂b₁b₀Satisfies the following formula:

when Im is_kWhen b is greater than or equal to 0, b ₀0, otherwise, b₀＝1；

When Re_kWhen b is greater than or equal to 0, b₁0, otherwise, b₁＝1；

When P (k) < T, b₂When P (k) is not less than T, b₂＝(Re_k<0)&(Re_k ³<0)|(Re_k>＝0)&(Re_k ³>＝0)；

When P (k) < T, b₃When P (k) is not less than T, b₃＝(Im_k<0)&(Im_k ³>＝0)|(Im_k>＝0)&(Im_k ³<0) Wherein "&"represents the logical operator" and ", i.e., satisfied simultaneously," | "represents the logical operator" or ".

As an improvement of the above method, when the received signal is a 32APSK modulated signal, the method specifically includes:

when the received signal is a 32APSK modulation signal, Q is 4, and the phase is rotated by an angle

Performing 4 power of exponentiation on the signal q (k) after QPD algorithm phase deviation compensation

Rotating the phase to obtain a signal z (k);

performing power detection on the signal z (k) to obtain a signal power detection value P (k), wherein the first power decision threshold is T₁The second power decision threshold is T₂，

When P (k) > ═ T₂When the judgment symbol is positioned in the outer circle, the sum of the 4 th power operation is obtained

The phase-rotated signal is subjected to demapping of the received signal to obtain bit b of the corresponding constellation point from high to low₄b₃b₂b₁b₀Satisfies the following formula:

(Re_k ⁴＞＝0&Im_k ⁴＞＝0)&(Re_k＞＝T₂)

b₄b₃b₂b₁b₀＝11000；

(Re_k ⁴＞＝0&Im_k ⁴＞＝0)&(Re_k＜-T₂)

b₄b₃b₂b₁b₀＝11110；

(Re_k ⁴＞＝0&Im_k ⁴＞＝0)&(Im_k＞＝T₂)&(Re_k＜T₂)&(Re_k＞＝-T₂)

b₄b₃b₂b₁b₀＝01101；

(Re_k ⁴＞＝0&Im_k ⁴＞＝0)&(Im_k＜-T₂)&(Re_k＜T₂)&(Re_k＞＝-T₂)

b₄b₃b₂b₁b₀＝01011；

(Re_k ⁴＜0&Im_k ⁴＞＝0)&(Re_k＞＝0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝01000；

(Re_k ⁴＜0&Im_k ⁴＞＝0)&(Re_k＞＝0&Im_k＜0)

b₄b₃b₂b₁b₀＝11011；

(Re_k ⁴＜0&Im_k ⁴＞＝0)&(Re_k＜0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝11101；

(Re_k ⁴＜0&Im_k ⁴＞＝0)&(Re_k＜0&Im_k＜0)

b₄b₃b₂b₁b₀＝01110；

(Re_k ⁴＜0&Im_k ⁴＜0)&(Re_k＞＝0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝11001；

(Re_k ⁴＜0&Im_k ⁴＜0)&(Re_k＞＝0&Im_k＜0)

b₄b₃b₂b₁b₀＝01010；

(Re_k ⁴＜0&Im_k ⁴＜0)&(Re_k＜0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝01100；

(Re_k ⁴＜0&Im_k ⁴＜0)&(Re_k＜0&Im_k＜0)

b₄b₃b₂b₁b₀＝11111；

(Re_k ⁴＞＝0&Im_k ⁴＜0)&(Re_k＞＝0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝01001；

(Re_k ⁴＞＝0&Im_k ⁴＜0)&(Re_k＞＝0&Im_k＜0)

b₄b₃b₂b₁b₀＝11010；

(Re_k ⁴＞＝0&Im_k ⁴＜0)&(Re_k＜0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝11100；

(Re_k ⁴＞＝0&Im_k ⁴＜0)&(Re_k＜0&Im_k＜0)

b₄b₃b₂b₁b₀＝01111；

wherein, Re_k ⁴，Im_k ⁴Respectively representing the real and imaginary parts of the signal z (k)'&"denotes the logical operator" AND ", i.e., satisfied simultaneously;

when (P (k) < T₂)&(P(k)＞＝T₁) When the constellation point is located in the space, the ring where the decision symbol is located is a central circle, and the demapping of the received signal is carried out according to the power of 3 and the signal z (k) after 0 phase rotation to obtain the bit b of the corresponding constellation point from high to low₄b₃b₂b₁b₀Satisfies the following formula:

(Re_k ³＞＝0&Im_k ³＞＝0)&(Re_k＞＝0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝10000；

(Re_k ³＞＝0&Im_k ³＞＝0)&(Re_k＜0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝00100；

(Re_k ³＞＝0&Im_k ³＞＝0)&(Re_k＜0&Im_k＜0)

b₄b₃b₂b₁b₀＝00111；

(Re_k ³＜0&Im_k ³＞＝0)&(Re_k＞＝0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝0；

(Re_k ³＜0&Im_k ³＞＝0)&(Re_k＜0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝10100；

(Re_k ³＜0&Im_k ³＞＝0)&(Re_k＞＝0&Im_k＜0)

b₄b₃b₂b₁b₀＝00011；

(Re_k ³＜0&Im_k ³＜0)&(Re_k＞＝0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝00001；

(Re_k ³＜0&Im_k ³＜0)&(Re_k＜0&Im_k＜0)

b₄b₃b₂b₁b₀＝10110；

(Re_k ³＜0&Im_k ³＜0)&(Re_k＞＝0&Im_k＜0)

b₄b₃b₂b₁b₀＝00010；

(Re_k ³＞＝0&Im_k ³＜0)&(Re_k＜0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝00101；

(Re_k ³＞＝0&Im_k ³＜0)&(Re_k＜0&Im_k＜0)

b₄b₃b₂b₁b₀＝00110；

(Re_k ³＞＝0&Im_k ³＜0)&(Re_k＞＝0&Im_k＜0)

b₄b₃b₂b₁b₀＝10010；

wherein, Re_k ³，Im_k ³Respectively representing the real part and the imaginary part of a signal z (k) after a power of 3 operation and a phase rotation of 0;

when P (k) < T₁Then, the ring where the decision symbol is located is an inner circle, and the received signal is demapped to obtain the bit b of the corresponding constellation point from high to low₄b₃b₂b₁b₀Satisfies the following formula:

a multiplexing Q-power demapping system based on a DVB-S2 system, characterized in that the system comprises: the QPD algorithm phase offset compensation module, the Q power operation module, the power detection module and the symbol decision module; the Q power operation module and the power detection module are reusable modules;

the QPD algorithm phase deviation compensation module is used for carrying out QPD algorithm phase deviation compensation on the received signals of the DVB-S2 system;

the Q power operation module is used for receiving signals and modulation mode signals of a DVB-S2 system, determining the modulation type of the received signals according to the modulation mode signals, and performing corresponding Q power operation on the received signals after QPD algorithm phase offset compensation, wherein Q is an integer greater than or equal to 0, and the Q power operation is Q power operation and corresponding phase rotation;

the power detection module is used for carrying out power detection on the signal subjected to Q power operation;

the symbol decision module is used for deciding a ring where a symbol is located according to the relation between the power detection value and the power decision threshold value; and performing demapping on the received signal according to the received signal, the signal after Q power operation and the ring where the decision symbol is located to obtain a corresponding constellation point bit.

Compared with the prior art, the invention has the advantages that:

1. under different modulation modes, the error code performance of the algorithm is superior to that of an amplitude and phase-based demapping algorithm and an amplitude-based demapping algorithm, and is the same as that of an improved amplitude-based demapping algorithm and a QPDemapping algorithm;

2. the algorithm resource consumption of the invention is lower than that of other comparatives;

3. the algorithm of the invention has reusability, can reduce DSP resource consumption after multiplexing Q power operation and power detection, and can be better applied to a DVB-S2 system.

Drawings

Fig. 1 is a 16APSK modulation constellation;

FIG. 2 is a prior art amplitude-based demapping algorithm vs 16APSK modulation b₂Processing of bit binary coding;

FIG. 3 is a prior art amplitude-based demapping algorithm vs 16APSK modulation b₃Processing of bit binary coding;

FIG. 4 demapping decision threshold analysis;

FIG. 5 is a diagram of a prior art improved 16APSK modulation b based on an amplitude demapping algorithm₂Processing of bit binary coding;

FIG. 6 is a diagram of a prior art improved 16APSK modulation b based on an amplitude demapping algorithm₃Processing of bit binary coding;

fig. 7 is a comparison of signal constellations before and after Q-power arithmetic processing according to the present invention, where fig. 7(a) is QPSK, fig. 7(b) is 8PSK, fig. 7(c) is 16APSK, and fig. 7(d) is 32 APSK;

FIG. 8 is a schematic diagram of the QPdemapping algorithm of the present invention;

FIG. 9 is a schematic diagram of the RQPDemapping algorithm of the present invention;

fig. 10 is a simulation of improved hard decision demapping algorithm for QPSK, 8PSK, 16APSK, and 32APSK under different signal-to-noise ratios.

Detailed Description

The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and examples.

Based on the distribution characteristics of the constellation diagrams of the four modulation modes of DVB-S2, the invention provides a low-complexity high-reliability reusable Q-power demapping algorithm (RQdemapping algorithm), which carries out symbol judgment on original constellation points and constellation points subjected to Q-power operation processing, thereby reducing the complexity of algorithm realization. In order to verify the performance of the algorithm, the method is realized on an FPGA xcku040-ffva1156-2-e hardware platform.

In the VCM link design of the DVB-S2 system, the modulation mode can be selected in a self-adaptive mode according to the channel condition, the low-order modulation mode is selected when the link margin is low, the high-order modulation mode is selected when the link margin is high, and the inter-satellite link resources are fully utilized. The modulation modes that can be supported by the VCM mode of the DVB-S2 system are QPSK, 8PSK, 16APSK and 32APSK, and the demapping algorithms of the four modulation modes of QPSK, 8PSK, 16APSK and 32APSK are mainly studied herein. Firstly, performing performance analysis on a demapping algorithm based on amplitude and phase, a demapping algorithm based on amplitude and an improved demapping algorithm based on amplitude; then, in order to improve the error code performance of the demapping algorithm and simplify the algorithm implementation structure, a Q-power demapping algorithm is provided; and then, in order to further optimize the structure of the QPDemapping algorithm and improve reusability, a reusable Q-power demapping algorithm (RQPPDemamapping algorithm) is provided by combining a Q-power Polarity Decision (QPD) carrier phase recovery algorithm in the DVB-S2 standard.

Assuming that QPSK, 8PSK, 16APSK and 32APSK modulated signals pass through an AWGN channel and timing synchronization and carrier recovery have been completed, the received signal can be represented as

r_k＝A*C_k+N_k＝Re_k+j*Im_k (1)

In the formula: a is channel gain, C_kFor modulated transmission signals, N_kTo be normally distributed, white Gaussian noise, Re_kAnd Im_kRespectively the real and imaginary parts of the received signal.

1 analysis of conventional demapping algorithms

1.1 amplitude and phase based demapping Algorithm

The amplitude R and phase θ of the received signal can be expressed as

And (3) calculating the amplitude R and the phase theta by using the formula (1) and the formula (2), judging the ring where the symbol is located according to the amplitude R value, and judging the area where the symbol is located according to the phase theta value, thereby judging the signal mapping symbol.

For the constellation diagram of 16APSK modulation, as shown in FIG. 1, each constellation point is represented by 4 binary codes, and the bits of the constellation point are sequentially represented as b from high to low₃b₂b₁b₀. The constellation diagram of the 16APSK modulation of the DVB-S2 standard is shown in fig. 1, where R1 and R2 are the inner and outer circle radii, respectively.

As shown in fig. 2, the amplitude and phase based demapping algorithm decision b₀、b₁、b₂、b₃The method comprises the following steps:

(1) if Im_kIf > 0, then b ₀0, otherwise b₀＝1。

(2) If Re_kIf > 0, then b ₁0, otherwise b₁＝1。

(3) If it is

Then b is₂＝1,b₃＝1。

(4) If it is

And theta satisfies

Or

Or

Or

Then b is₂＝0,b ₃0; if it is

And theta satisfies

Or

Or

Then b is₂＝1,b ₃0; if it is

And theta satisfies

Or

Then b is₂＝0,b₃＝1。

The algorithm needs to perform inverse trigonometric operation on the demapping of the modulation signal, and the calculation complexity is high.

1.2 amplitude-based demapping Algorithm

Amplitude and phase based demapping algorithms are improved to reduce algorithm computation complexityA low complexity amplitude-based demapping algorithm is presented. The algorithm is used for 16APSK modulation mode b₀、b₁The decision method of (a) is consistent with a demapping algorithm based on amplitude and phase; the algorithm adopts a 16APSK modulation mode b₂、b₃The corresponding constellation diagram is processed as shown in fig. 2 and fig. 3.

R1 and R2 are respectively the inner and outer circle radiuses, K1, K2, K3 and K4 are respectively expressed as

Amplitude-based demapping algorithm decision b₂、b₃The method comprises the following steps:

(1) if K2 is not more than Im_kK is less than or equal to K1, then b ₂1, otherwise b₂＝0。

(2) If K4 is not more than Re_kK is less than or equal to K3, then b ₃1, otherwise b₃＝0。

The algorithm does not need to calculate the phase, simplifies the calculation complexity of the algorithm, can obtain a judgment result in a shorter time, is not easy to cause time delay, is beneficial to the synchronization of a sending end and a receiving end, but loses certain precision, and is not suitable for 32APSK modulation.

1.3 improved amplitude-based demapping Algorithm

As shown in fig. 4, when the signal distortion is high, the constellation points are relatively scattered, and the decision of the amplitude-based demapping algorithm with the thresholds K1 and K3 will cause b₂、b₃Misjudgment results in larger error rate, and if judgment is carried out by using thresholds L1 and L3, b can be accurately judged₂、b₃. Improved 16APSK modulation mode b based on amplitude demapping algorithm₀、b₁The decision method of (a) is consistent with a demapping algorithm based on amplitude and phase; the algorithm adopts a 16APSK modulation mode b₂、b₃The corresponding constellation diagram is processed as shown in fig. 5 and fig. 6. R1 and R2 are respectively the inner and outer circle radiuses; l1, L2, L3 and L4 are respectively represented as

The algorithm decides 16APSK modulation b₂、b₃The method comprises the following steps:

(1) if it is

Then b is₂＝1,b₃＝1。

(2) If it is

And satisfy L1 < 0, L2 > 0 or L1 > 0, L2 < 0, then b ₂1, otherwise b₂＝0。

(3) If it is

And satisfy L3 > 0, L4 > 0 or L3 < 0, L4 < 0, then b ₃1, otherwise b₃＝0。

The demapping algorithm is high in precision, and the calculation complexity is slightly increased compared with the amplitude-based demapping algorithm.

Embodiment 1 of the present invention provides a reusable Q-th power demapping algorithm based on a DVB-S2 system, including:

example 1

1 QPdemapping algorithm

In order to improve the error code performance of the demapping algorithm and simplify the algorithm implementation structure, a Q-power demapping algorithm is provided. The algorithm specifies the values of the power operation order Q and the phase rotation angle beta of different modulation signals as shown in Table 1. As shown in fig. 7(a), (b), (c), and (d), after different modulation schemes are subjected to Q power operation, the constellation maps all have a certain degree of convergence, and are converted into QPSK-like modulation constellation maps.

TABLE 1 values of the power operation order Q and the phase rotation angle beta of different modulation signals

Suppose that a 16PSK modulated signal can be represented as

r_k＝(Re_k+j*Im_k) (8)

The signal after the power of 3 operation can be expressed as

(r_k)³＝(Re_k+j*Im_k)³＝Re_k ³+j*Im_k ³ (9)

The comparison between the phase of the 16APSK modulated constellation point after the 3-th power operation and the phase of the original constellation point is shown in table 2.

Table 216 comparison of phase of APSK original constellation point and phase of constellation point processed to power 3

As can be seen from table 2, after the 16APSK modulated signal is processed to the power of 3, the 12 constellation points on the outer circle are fixedly distributed at 4 corresponding points in the four quadrants, and the phases are pi/4, 3 pi/4, 5 pi/4 and 7 pi/4, respectively. Thus, the QPdemapping algorithm decides b₀、b₁、b₂、b₃The steps are as follows:

(1) if Im_kB is not less than 0₀0, otherwise, b₀＝1。

(2) If Re_kB is not less than 0₁0, otherwise, b₁＝1。

(3) If it is

Then b is₂＝1,b₃＝1。

(4) If it is

And satisfy Re_k＜0,Re_k ³< 0 or Re_k≥,Re_k ³B is not less than 0₂1, otherwise, b ₂0; if it is

And satisfy Im_k＜0,Im_k ³Not less than 0 or Im_k≥0,Im_k ³< 0, then b ₃1, otherwise, b₃＝0。

The algorithm utilizes the constellation diagram after Q-power operation processing and the original constellation diagram to carry out symbol judgment without precision loss, and the schematic diagram is shown in FIG. 8.

2 RQPDemapping algorithm

In order to further optimize the structure of the QPDemapping algorithm and improve reusability, a reusable Q-power demapping algorithm (RQPDemapping algorithm) is proposed in combination with a Q-th power Polarity Decision (QPD) carrier phase recovery algorithm in the DVB-S2 standard, and a schematic diagram thereof is shown in fig. 8. As can be seen from fig. 8 and fig. 9, the RQPDemapping algorithm and the QPDemapping algorithm have the same implementation principle, but the RQPDemapping algorithm may use the Q power operation and the power detection of the QPD carrier phase recovery module. And accompanying the input signal is also a mode indicating the current modulation mode, where 0 denotes QPSK modulation, 1 denotes 8PSK modulation, 2 denotes 16APSK modulation, and 3 denotes 32APSK modulation. Judging whether the mode determines to carry out Q power operation and power detection, if the mode is 0, the Q power operation and the power detection are not needed; the power detection is not needed when the Q power operation is needed for 1; the power of Q operation and power detection are required for 2 or 3. Performing Q power operation and phase rotation on the signal Q (k) after QPD algorithm phase offset compensation to obtain a signal z (k) of

z(k)＝[q(k)]^Q e^jβ (10)

Where Q is the order of the power operation and β is the angle of phase rotation, the rules can be found in table 1. Supposing that the power decision threshold is T, the signal power detection value is P (k), and when P (k) is more than or equal to T, the ring where the power detection judgment symbol is located is an excircle; when P (k) < T, the circle where the power detection judgment symbol is located is an inner circle.

According to table 1, the demapping process is as follows for different modulated signals:

1)QPSK

when the received signal is a QPSK modulation signal, Q is 0, and the angle β of phase rotation is 0, Q-power rotation is not required;

namely: when Re_kWhen b is greater than or equal to 0, b ₁0, otherwise, b ₁1 is ═ 1; when Im is_kWhen b is greater than or equal to 0, b ₀0, otherwise, b₀＝1。

2)8PSK

obtaining a signal z (k);

based on the received signal q (k), a power of 2 operation and

the phase-rotated signal z (k) after Q power operation is subjected to demapping of the received signal to obtain the bits b of the corresponding constellation point from high to low₂b₁b₀Satisfies the following formula:

wherein, Re_k ²And Im_k ²Shows the result of the Q-th power operation on the 8PSK signal (8PSK signal to the power of 2 and rotation)

Latter result), Re_kRepresenting the real part, Im, of an 8PSK signal_kRepresenting the imaginary part of the 8PSK signal.

3)16APSK

performing power operation of 3 and phase rotation of 0 on the signal Q (k) subjected to phase offset compensation by the QPD algorithm to obtain a signal z (k) subjected to power operation of Q;

as can be seen from the formula (13), after Q power operation and power detection are multiplexed, the RQPDemapping algorithm does not need multiplication, the structure is simple, resource consumption can be greatly reduced, and the error code performance is not changed compared with the QPDemapping algorithm.

4)32APSK

Rotating the phase to obtain a signal z (k) after Q power operation;

when (P (k) < T₂)&(P(k)＞＝T₁) When the received signal is demapped, the bit b of the constellation point from high to low is obtained₄b₃b₂b₁b₀Satisfies the following formula:

3, improving the simulation and hardware implementation of the demapping algorithm:

3.1 demapping Algorithm simulation and analysis

By integrating the demapping algorithm based on the amplitude and the phase, the demapping algorithm based on the amplitude, and the improved error code performance and calculation complexity consideration based on the demapping algorithm based on the amplitude, the improved simulation based on the demapping algorithm based on the amplitude and the QPDemapping algorithm is performed on the four kinds of modulations of QPSK, 8PSK, 16APSK, and 32APSK under different signal-to-noise ratios, and the error rate result shown in fig. 10 is obtained.

As can be seen from fig. 10, compared with the amplitude and phase based demapping algorithm and the amplitude based demapping algorithm, the improved error rate performance based on the amplitude demapping algorithm and the QPDemapping algorithm is the same and optimal in the QPSK, 8PSK, 16APSK, and 32APSK four modulation modes. Under four modulation modes of QPSK, 8PSK, 16APSK and 32APSK, the error rate is reduced to 0 and is respectively about 16dB, 22dB, 24dB and 28dB, and the performance is good.

3.2 Demapping Module implementation

The RQPDemapping algorithm is tested on the basis of an FPGA xcku040-ffva1156-2-e hardware platform, and the hardware description language is Verilog HDL.

Under QPSK, 8PSK, 16APSK and 32APSK modulations, the resource consumption of the QPDemapping algorithm, the RQPDemapping algorithm and the improved amplitude-based demapping algorithm are shown in table 3. As can be seen from table 3, compared with the improved amplitude-based demapping algorithm, the resource consumption of the QPDemapping algorithm is reduced under three modulations of 8PSK, 16APSK and 32APSK, and as the modulation order increases, the advantages of the QPDemapping algorithm are gradually highlighted; the RQPPDemapping algorithm greatly reduces the resource consumption under three types of modulation of 8PSK, 16APSK and 32APSK, and is obviously lower than the improved amplitude-based demapping algorithm. The QPDemapping algorithm does not need to carry out Q power operation on QPSK modulation, so the resource consumption of the QPDemapping algorithm and the resource consumption of the RQPPDemamapping algorithm are the same under the QPSK modulation. Therefore, the RQPPDemapping algorithm has the characteristics of high performance, low complexity, easiness in implementation and the like.

Table 3 shows QPDemapping algorithm, RQPPDemamapping algorithm and improved resource consumption based on amplitude demapping algorithm under different modulation modes (B: BRAM; D: DSP; L: LUT; R: Register)

TABLE 3 comparison of resource consumption by different algorithms

In order to solve the limitations of low precision, high complexity, more resource consumption and the like of the traditional hard decision demapping algorithm, a reusable Q-power demapping algorithm is provided. By combining the characteristics of the DVB-S2 system phase recovery algorithm, a QPDemapping algorithm or an RQPPDemamapping algorithm can be flexibly selected. Comparing error rate curves of different hard decision algorithms under four modulation modes of QPSK, 8PSK, 16APSK and 32APSK, and optimizing the performance of RQPPDemapping algorithm, QPDemapping algorithm and improved amplitude-based demapping algorithm; the resource consumption of the RQPDemapping algorithm, the QPDemapping algorithm and the improved amplitude-based demapping algorithm under the four modulation modes of QPSK, 8PSK, 16APSK and 32APSK is analyzed, the resource consumption of the RQPDemapping algorithm is minimum, and the RQPDemapping algorithm can be better applied to a DVB-S2 system.

Example 2

Embodiment 2 of the present invention provides a reusable Q-power demapping system based on a DVB-S2 system, where the system includes: the QPD algorithm phase offset compensation module, the Q power operation module, the power detection module and the symbol decision module; the Q power operation module and the power detection module are reusable modules;

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and are not limited. Although the present invention has been described in detail with reference to the embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for de-mapping a reusable power Q based on a DVB-S2 system, the method comprising:

2. The multiplexing Q-power demapping method based on DVB-S2 system of claim 1, wherein the determining the modulation type of the received signal according to the modulation mode signal specifically comprises:

when mode is 0, the received signal is QPSK modulated;

when the mode is 1, the received signal is 8PSK modulation;

when mode is 2, the received signal is 16APSK modulation;

when mode is 3, the received signal is 32APSK modulated.

3. The method of claim 2, wherein the received signals are represented by the following equation:

q_k＝(Re_k+j*Im_k)

4. The multiplexing Q-power demapping method based on the DVB-S2 system according to claim 3, wherein when the received signal is a QPSK modulated signal, the method specifically includes:

when Re_kWhen b is greater than or equal to 0, b₁0, otherwise, b₁＝1；

When Im is_kWhen b is greater than or equal to 0, b₀0, otherwise, b₀＝1。

5. The multiplexing Q-power demapping method based on DVB-S2 system of claim 3, wherein when the received signal is 8PSK modulated signal, the method specifically comprises:

obtaining a signal z (k);

carrying out power detection on z (k) to obtain a signal power detection value P (k), and judging that symbols are on a circle;

based on the received signal q (k), a power of 2 operation and

(Re_k ²≥0)&(Im_k ²≥0)&(Re_k≥0)

b₂b₁b₀＝001；

(Re_k ²≥0)&(Im_k ²≥0)&(Re_k<0)

b₂b₁b₀＝010；

(Re_k ²<0)&(Im_k ²≥0)&(Re_k≥0)

b₂b₁b₀＝000；

(Re_k ²<0)&(Im_k ²≥0)&(Re_k<0)

b₂b₁b₀＝011；

(Re_k ²<0)&(Im_k ²<0)&(Im_k≥0)

b₂b₁b₀＝100；

(Re_k ²<0)&(Im_k ²<0)&(Im_k<0)

b₂b₁b₀＝111；

(Re_k ²≥0)&(Im_k ²<0)&(Im_k≥0)

b₂b₁b₀＝110；

(Re_k ²≥0)&(Im_k ²<0)&(Im_k<0)

b₂b₁b₀＝101

6. The multiplexing Q-power demapping method based on the DVB-S2 system according to claim 3, wherein when the received signal is a 16APSK modulated signal, the method specifically includes:

based on the received signal q (k), the power of 3 and the phase-rotated signal of 0The ring where the number and the decision symbol are located is used for demapping the received signal to obtain the bit b of the corresponding constellation point from high to low₃b₂b₁b₀Satisfies the following formula:

when Im is_kWhen b is greater than or equal to 0, b₀0, otherwise, b₀＝1；

When Re_kWhen b is greater than or equal to 0, b₁0, otherwise, b₁＝1；

7. The multiplexing Q-power demapping method based on DVB-S2 system of claim 3, wherein when the received signal is a 32APSK modulated signal, the method specifically comprises:

Rotating the phase to obtain a signal z (k);

When P (k) > ═ T₂When the symbol is judged, the ring is the excircle, and the judgment is carried out according to the number of times of 4Sum of square exponentiation

The phase-rotated signal z (k) is subjected to demapping of the received signal to obtain bits b of the corresponding constellation point from high to low₄b₃b₂b₁b₀Satisfies the following formula:

(Re_k ⁴＞＝0&Im_k ⁴＞＝0)&(Re_k＞＝T₂)

b₄b₃b₂b₁b₀＝11000；

(Re_k ⁴＞＝0&Im_k ⁴＞＝0)&(Re_k＜-T₂)

b₄b₃b₂b₁b₀＝11110；

b₄b₃b₂b₁b₀＝01101；

b₄b₃b₂b₁b₀＝01011；

(Re_k ⁴＜0&Im_k ⁴＞＝0)&(Re_k＞＝0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝01000；

(Re_k ⁴＜0&Im_k ⁴＞＝0)&(Re_k＞＝0&Im_k＜0)

b₄b₃b₂b₁b₀＝11011；

(Re_k ⁴＜0&Im_k ⁴＞＝0)&(Re_k＜0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝11101；

(Re_k ⁴＜0&Im_k ⁴＞＝0)&(Re_k＜0&Im_k＜0)

b₄b₃b₂b₁b₀＝01110；

(Re_k ⁴＜0&Im_k ⁴＜0)&(Re_k＞＝0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝11001；

(Re_k ⁴＜0&Im_k ⁴＜0)&(Re_k＞＝0&Im_k＜0)

b₄b₃b₂b₁b₀＝01010；

(Re_k ⁴＜0&Im_k ⁴＜0)&(Re_k＜0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝01100；

(Re_k ⁴＜0&Im_k ⁴＜0)&(Re_k＜0&Im_k＜0)

b₄b₃b₂b₁b₀＝11111；

(Re_k ⁴＞＝0&Im_k ⁴＜0)&(Re_k＞＝0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝01001；

(Re_k ⁴＞＝0&Im_k ⁴＜0)&(Re_k＞＝0&Im_k＜0)

b₄b₃b₂b₁b₀＝11010；

(Re_k ⁴＞＝0&Im_k ⁴＜0)&(Re_k＜0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝11100；

(Re_k ⁴＞＝0&Im_k ⁴＜0)&(Re_k＜0&Im_k＜0)

b₄b₃b₂b₁b₀＝01111；

when (P (k) < T₂)&(P(k)＞＝T₁) When the judgment symbol is positioned in the circle, the circle in which the judgment symbol is positioned is a central circle; performing demapping on the received signal according to a 3-power operation and a 0-phase rotated signal z (k) to obtain bits b of a corresponding constellation point from high to low₄b₃b₂b₁b₀Satisfies the following formula:

(Re_k ³＞＝0&Im_k ³＞＝0)&(Re_k＞＝0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝10000；

(Re_k ³＞＝0&Im_k ³＞＝0)&(Re_k＜0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝00100；

(Re_k ³＞＝0&Im_k ³＞＝0)&(Re_k＜0&Im_k＜0)

b₄b₃b₂b₁b₀＝00111；

(Re_k ³＜0&Im_k ³＞＝0)&(Re_k＞＝0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝0；

(Re_k ³＜0&Im_k ³＞＝0)&(Re_k＜0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝10100；

(Re_k ³＜0&Im_k ³＞＝0)&(Re_k＞＝0&Im_k＜0)

b₄b₃b₂b₁b₀＝00011；

(Re_k ³＜0&Im_k ³＜0)&(Re_k＞＝0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝00001；

(Re_k ³＜0&Im_k ³＜0)&(Re_k＜0&Im_k＜0)

b₄b₃b₂b₁b₀＝10110；

(Re_k ³＜0&Im_k ³＜0)&(Re_k＞＝0&Im_k＜0)

b₄b₃b₂b₁b₀＝00010；

(Re_k ³＞＝0&Im_k ³＜0)&(Re_k＜0&Im_k＞＝0)

b₄b₃b₂b₁b₀＝00101；

(Re_k ³＞＝0&Im_k ³＜0)&(Re_k＜0&Im_k＜0)

b₄b₃b₂b₁b₀＝00110；

(Re_k ³＞＝0&Im_k ³＜0)&(Re_k＞＝0&Im_k＜0)

b₄b₃b₂b₁b₀＝10010；

when P (k) < T₁When the judgment symbol is positioned in the ring, the judgment symbol is positioned in the ring; de-mapping the received signal to obtain the bit b from high to low of the corresponding constellation point₄b₃b₂b₁b₀Satisfies the following formula:

(Re_k>＝0)&(Im_k>＝0)

b₄b₃b₂b₁b₀＝10001；

(Re_k>＝0)&(Im_k<0)

b₄b₃b₂b₁b₀＝10011；

(Re_k<0)&(Im_k>＝0)°

b₄b₃b₂b₁b₀＝10101；

(Re_k<0)&(Im_k<0)

b₄b₃b₂b₁b₀＝10111 。

8. a multiplexing Q-power demapping system based on a DVB-S2 system, characterized in that the system comprises: the QPD algorithm phase offset compensation module, the Q power operation module, the power detection module and the symbol decision module; the Q power operation module and the power detection module are reusable modules;