CN116016088A - Demapping method for satellite communication signal 16APSK - Google Patents
Demapping method for satellite communication signal 16APSK Download PDFInfo
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Abstract
The invention discloses a demapping method of satellite communication signal 16APSK, comprising the following steps: normalizing the constellation diagram of the modulated signal; judging whether the constellation points are positioned on the outer circle or the inner circle of the constellation diagram; calculating b according to the inner circle mapping rule and the outer circle mapping rule respectively 3 b 2 b 1 b 0 ，b 3 b 2 b 1 b 0 Four binary coded mapping for 16APSK, where b 3 Is in the high position, b 0 Is in a low position; b obtained 3 b 2 b 1 b 0 Merging to obtain bit data corresponding to one symbol; receiving the next constellation point, repeating the steps 2-4 until the bit mapping of the last symbol is completed, and finally merging the output bit data into bit stream data to complete the mapping from the constellation point to the bit stream, thereby completing the demapping of 16 APSK; the invention can effectively eliminate the situation of internal and external circle judgment errors caused by different gamma values.
Description
Technical Field
The invention relates to the technical field of demodulation and decoding of a communication system, in particular to a method for demapping a satellite communication signal 16 APSK.
Background
When designing a modulation signal constellation for a satellite channel, in order to improve the utilization rate of a channel frequency band, high-order modulation should be adopted, and fluctuation of the amplitude of a modulation signal should be reduced as much as possible to adapt to a nonlinear power amplifier, so that an APSK signal with a round constellation diagram and a small number of circumferences becomes one of the future development trends of modulation technologies in satellite communication.
The second generation of the global satellite digital video broadcasting standard DVB-S2 standard was proposed by the international digital video broadcasting organization in 2003. The DVB-S2 can select four different modulation modes according to different practical application systems, wherein 16APSK is one of the selectable modulation modes.
In order to make satellite communication technology play a greater role in modern construction of future countries, research on key modem technology in satellite communication should be focused, while demapping is a ring in demodulation technology, and it is self-evident that the correct mapping of signals is key for the next step, and if mapping is wrong, the information recovered later is completely ineffective.
Disclosure of Invention
In order to solve the problems in the prior art, the invention aims to provide a method for demapping the satellite communication signal 16APSK, which can effectively eliminate the situation of internal and external circle judgment errors caused by different gamma values.
In order to achieve the above purpose, the invention adopts the following technical scheme: a method of demapping a satellite communications signal 16APSK, comprising the steps of:
step 2, judging whether the constellation points are positioned on the outer circle or the inner circle of the constellation diagram;
step 3, calculating b according to the inner circle mapping rule and the outer circle mapping rule respectively 3 b 2 b 1 b 0 ，b 3 b 2 b 1 b 0 Four binary coded mapping for 16APSK, where b 3 Is in the high position, b 0 Is in a low position;
step 4, obtaining b 3 b 2 b 1 b 0 Merging to obtain bit data corresponding to one symbol;
and 5, receiving the next constellation point, repeating the steps 2-4 until the bit mapping of the last symbol is completed, and finally merging the output bit data into bit stream data to complete the mapping from the constellation point to the bit stream, thereby completing the demapping of the 16 APSK.
As a further improvement of the present invention, the step 1 is specifically as follows:
(1) Calculating the maximum amplitude of constellation points, and setting the amplitude of receiving constellation points as r i The maximum amplitude is max (|r) i I), the constellation point amplitude value is roughly normalized to obtain a result r i _norm＝r i /max(|r i I), wherein max (·) represents the maximum value in the data sequence;
(2) Find r i Satisfying |r in_norm i Points of _norm > (1+γ)/(2×γ), the set of all points is set to Ω, where γ is the ratio of the outer radius to the inner radius of the constellation;
(3) Taking an average value of the modes of points in omega, wherein the average value is alpha;
(4) Constellation normalization correction: r is (r) i ＝r i /(max(|r i |)*α)。
As a further improvement of the present invention, in step 2, if the modulus of the constellation point is greater than (1+γ)/(2 γ), then the constellation point is determined to be located on the outer circle, otherwise, the constellation point is determined to be located on the inner circle.
As a further improvement of the present invention, in step 3, b is calculated according to the inner circle mapping rule 3 b 2 b 1 b 0 The method specifically comprises the following steps:
inner circle and outer circle b 0 The output of (2) is judged according to the formula (1):
wherein imag (·) represents the complex signal taking its imaginary part;
inner circle and outer circle b 1 The output of (2) is judged according to the formula:
wherein, real (·) represents the complex signal taking its real part;
b of the inner circle 2 ＝b 3 ＝1；
Outer circle b 2 The output of (2) is judged according to the formula (3):
outer circle b 3 The output of (2) is judged according to the formula (4):
wherein A is i ＝mod(angle(r i ) 2 pi), mod represents the remainder, angle (·) represents the calculated complex sequence phase angle, range [ -pi, pi),&&the logical and operation is represented by a sequence of logical and operations, the expression "logical or" operation.
The beneficial effects of the invention are as follows:
the received signal is influenced by various gains in a transmission channel, so that the radius of a received constellation is different from that of a transmitted constellation, and the demapping result is wrong; by utilizing the demapping method provided by the invention, the constellation is normalized before mapping, so that the problem that the received constellation and the transmitted constellation have different radiuses is effectively solved; in addition, the judgment threshold of the inner circle and the outer circle of the constellation point is hooked with the value of gamma, so that the situation of error judgment of the inner circle and the outer circle caused by different gamma values can be effectively eliminated.
Drawings
FIG. 1 is a flow chart of an embodiment of the present invention;
FIG. 2 is a constellation diagram of a 16APSK signal according to an embodiment of the invention;
FIG. 3 is a diagram of an excircle b of 16APSK in an embodiment of the invention 2 A binary coded representation of (2);
FIG. 4 is a diagram of an excircle b of 16APSK in an embodiment of the invention 3 Is a binary coded representation of (c).
Detailed Description
Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
Examples
16APSK modulationThe constellation diagram of the signal is shown in FIG. 2, the 16APSK constellation has 2 concentric circles with radii R 1 And R is 2 The inner circle is 4 points, the outer circle is 12 points, and the signal set expression is:
ratio γ=r of outer radius to inner radius 2 /R 1 The gamma values corresponding to different code rates are shown in table 1:
table 1 gamma values corresponding to different code rates of 16APSK
| Code rate | Modulation/coding spectral efficiency | γ |
| 2/3 | 2.67 | 3.15 |
| 3/4 | 3.00 | 2.85 |
| 4/5 | 3.20 | 2.75 |
| 5/6 | 3.33 | 2.70 |
| 8/9 | 3.56 | 2.60 |
| 9/10 | 3.60 | 2.57 |
The transmission symbol x of 16APSK represents four binary coded maps b 3 b 2 b 1 b 0 Wherein b 3 Is in the high position, b 0 Is low.
As shown in fig. 1, the present embodiment provides a method for demapping a satellite communication signal 16APSK, which includes the following steps:
(1) Calculating the maximum amplitude of constellation points, and setting the amplitude of receiving constellation points as r i The maximum amplitude is max (|r) i I), the constellation point amplitude value is roughly normalized to obtain a result r i _norm＝r i /max(|r i I), wherein max (·) represents the maximum value in the data sequence;
(2) Find r i Satisfying |r in_norm i Points of _norm > (1+γ)/(2×γ), the set of points is Ω;
(3) Taking an average value of the modes of points in omega, wherein the average value is alpha;
(4) Constellation normalization correction: r is (r) i ＝r i /(max(|r i |)*α)。
And 2, judging whether the constellation points are positioned in the inner circle or the outer circle. If the modulus of the constellation point > (1+gamma)/(2. Gamma.) then the constellation point is judged to be located on the outer circle, otherwise the constellation point is judged to be located on the inner circle.
Step 3, if the constellation point is located in the inner circle, as can be seen from fig. 2, b 0 The positions 0 are all above the Q axis, so the inner circle b 0 The output of (2) can be judged according to the formula (1); b 1 The positions 0 are all on the right side of the I axis, so the inner circle b 1 The output of (b) can be judged according to the formula (2) 2 ＝b 3 ＝1；
Wherein imag (·) represents the complex signal taking its imaginary part, real (·) represents the complex signal taking its real part;
step 4, if the constellation point is located at the outer circle, as can be seen from fig. 2, b 0 The position 0 is all above the Q axis, so the outer circle b 0 The output of (2) can be judged according to the formula (1); b 1 The position 0 is all positioned on the right side of the I axis, so the outer circle b 1 The output of (2) can be judged according to the formula; as can be seen from FIG. 3, b 2 The outer circle b is because =1 is located in the left and right two areas of the area sandwiched by the straight lines i=tan (pi/6) Q and i=tan (5 pi/6) Q 2 The output of (2) can be judged according to the formula (3); similarly, as can be seen from FIG. 4, b 3 =1 are located in the upper and lower two areas of the straight lines i=tan (pi/3) Q and i=tan (2pi/3) Q, so the outer circle b 3 The output of (2) can be judged according to the formula (4):
wherein A is i ＝mod(angle(r i ) 2 pi), mod represents the remainder, angle (·) represents the calculated complex sequence phase angle, range [ -pi, pi),&&the logical and operation is represented by a sequence of logical and operations, the expression "logical or" operation.
Step 5, b is obtained according to the steps 3 b 2 b 1 b 0 And combining to obtain bit data corresponding to one symbol.
And 6, receiving the next constellation point, repeating the steps 2 to 5 until the bit mapping of the last symbol is completed, and finally merging the output bit data into bit stream data to complete the mapping from the constellation point to the bit stream, thereby completing the demapping of the 16 APSK.
The foregoing examples merely illustrate specific embodiments of the invention, which are described in greater detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention.
Claims (4)
1. A method for demapping a satellite communications signal 16APSK, comprising the steps of:
step 1, normalizing a constellation diagram of a modulation signal;
step 2, judging whether the constellation points are positioned on the outer circle or the inner circle of the constellation diagram;
step 3, calculating b according to the inner circle mapping rule and the outer circle mapping rule respectively 3 b 2 b 1 b 0 ，b 3 b 2 b 1 b 0 Four binary coded mapping for 16APSK, where b 3 Is in the high position, b 0 Is in a low position;
step 4, obtaining b 3 b 2 b 1 b 0 Merging to obtain bit data corresponding to one symbol;
and 5, receiving the next constellation point, repeating the steps 2-4 until the bit mapping of the last symbol is completed, and finally merging the output bit data into bit stream data to complete the mapping from the constellation point to the bit stream, thereby completing the demapping of the 16 APSK.
2. The method for demapping a satellite communication signal according to claim 1, wherein step 1 is specifically as follows:
(1) Calculating the maximum amplitude of constellation points, and setting the amplitude of receiving constellation points as r i The maximum amplitude is max (|r) i I), the constellation point amplitude value is roughly normalized to obtain a result r i _norm＝r i /max(|r i I), wherein max (·) represents the maximum value in the data sequence;
(2) Find r i Satisfying |r in_norm i Points of _norm > (1+γ)/(2×γ), the set of all points is set to Ω, where γ is the ratio of the outer radius to the inner radius of the constellation;
(3) Taking an average value of the modes of points in omega, wherein the average value is alpha;
(4) Constellation normalization correction: r is (r) i ＝r i /(max(|r i |)*α)。
3. The method according to claim 2, wherein in step 2, if the modulus of the constellation point is greater than (1+γ)/(2×γ), then determining that the constellation point is located at the outer circle, and otherwise determining that the constellation point is located at the inner circle.
4. A method for demapping a satellite communications signal as in claim 3 wherein in step 3 b is calculated according to an inner circle mapping rule 3 b 2 b 1 b 0 The method specifically comprises the following steps:
inner circle and outer circle b 0 The output of (2) is judged according to the formula (1):
wherein imag (·) represents the complex signal taking its imaginary part;
inner circle and outer circle b 1 The output of (2) is judged according to the formula:
wherein, real (·) represents the complex signal taking its real part;
b of the inner circle 2 ＝b 3 ＝1；
Outer circle b 2 The output of (2) is judged according to the formula (3):
outer circle b 3 The output of (2) is judged according to the formula (4):
wherein A is i ＝mod(angle(r i ) 2 pi), mod represents the remainder, angle (·) represents the calculated complex sequence phase angle, range [ -pi, pi),&&the logical and operation is represented by a sequence of logical and operations, the expression "logical or" operation.
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| CN116527120A (en) * | 2023-06-30 | 2023-08-01 | 北京融为科技有限公司 | Signal mapping method and device based on satellite communication |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116527120A (en) * | 2023-06-30 | 2023-08-01 | 北京融为科技有限公司 | Signal mapping method and device based on satellite communication |
| CN116527120B (en) * | 2023-06-30 | 2023-11-14 | 北京融为科技有限公司 | Signal mapping method and device based on satellite communication |
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