CN100558096C - A kind of quadrature amplitude modulation demodulation method and device that is applied to communication system - Google Patents

Abstract

The invention provides a kind of quadrature amplitude modulation demodulation method that is applied to communication system, may further comprise the steps: step 1, receiving terminal adopt planisphere that the symbol that receives is shone upon, and obtain the final symbol of described symbol, and to this final symbol operated in saturation; Step 2 is determined the predetermined thresholds at different levels of the soft bit demodulation of M unit quadrature amplitude modulation, goes out each bit of this final symbol according to the final sign computation after this predetermined threshold and the described operated in saturation.Symbol preprocessing process among the present invention only comprises phase place adjustment and symbol adjustment, and calculate in the process of each bit of described final symbol and adopt plus and minus calculation mostly, therefore demodulating process is simple, demodulation performance is good, having solved the receiving terminal Block Error Rate sharply increases and causes the data transmission efficiency of network to reduce, and the defective that reduces in the data transmission efficiency that the complicated demodulation computing that receiving terminal carries out is caused.

Description

Quadrature amplitude modulation and demodulation method and device applied to communication system

Technical Field

The present invention relates to demodulation technologies in the field of communications, and in particular, to a quadrature amplitude modulation and demodulation method and apparatus applied to a communication system.

Background

With the rapid development of communication technology, the demand of people for transmitting more information on the limited communication network bandwidth is stimulated. In terms of Modulation schemes for communication, Quadrature Amplitude Modulation (QAM) can approach the limit of channel capacity more than channel resources occupied by other Modulation schemes when the bandwidth is limited, that is, QAM has higher transmission efficiency under the same bandwidth and transmission power.

For the above reasons, in high-speed data transmission, for example, in Wireless network communication such as Worldwide Interoperability for Microwave Access (WiMAX), satellite communication, optical cable communication, or in communication technologies under different standard communication protocols in the field of Mobile communication, for example, Global System for Mobile communication (GSM Global System for Mobile communication), Time Division synchronous Code Division Multiple Access (TD-S CDMA Time Division Multiple Access), Wireless Code Division Multiple Access (WCDMA Wireless CDMA), Code Division Multiple Access 2000(CDMA2000Code Division Multiple Access 2000), and various other technologies applied to high-speed data transmission, QAM methods such as 16QAM, 64QAM, even 256QAM, etc. are often used, and thus QAM is important, but the existing QAM methods or corresponding devices are due to the change of signal amplitude at the receiving end, therefore, the demodulation performance is reduced, the block error rate is increased rapidly, and the data transmission efficiency of the network is reduced; even though some prior art proposals for improving the above-mentioned drawbacks still require complex demodulation operations at the receiving end, these operations consume time, affect the demodulation capability of the receiving end, and still result in a reduction in the data transmission efficiency of the network.

Disclosure of Invention

The invention aims to provide a quadrature amplitude modulation and demodulation method and a quadrature amplitude modulation and demodulation device applied to a communication system, which solve the defects that the data transmission efficiency of a network is reduced due to the fact that the block error rate of a receiving end is increased sharply, and the data transmission efficiency is reduced due to the fact that too complex demodulation operation is carried out on the receiving end.

A quadrature amplitude modulation and demodulation method applied to a communication system, comprising the steps of: step one, the receiving end adopts a constellation diagram to map the received symbol, and adjusts the amplitude of a rotating symbol corresponding to the symbol according to a preset average power to obtain a final symbol

<math> <mrow> <msub> <mover> <mi>d</mi> <mo>^</mo> </mover> <mi>norm</mi> </msub> <mo>=</mo> <mrow> <mo>(</mo> <msqrt> <mi>K</mi> </msqrt> <mo>/</mo> <msqrt> <mrow> <mo>(</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>N</mi> </munderover> <msup> <mrow> <mo>|</mo> <mo>|</mo> <msub> <mover> <mi>d</mi> <mo>^</mo> </mover> <mi>rot</mi> </msub> <mrow> <mo>(</mo> <mi>i</mi> <mo>)</mo> </mrow> <mo>|</mo> <mo>|</mo> </mrow> <mn>2</mn> </msup> <mo>)</mo> </mrow> <mo>/</mo> <mi>N</mi> </msqrt> <mo>)</mo> </mrow> <mo>&times;</mo> <msub> <mover> <mi>d</mi> <mo>^</mo> </mover> <mi>rot</mi> </msub> <mo>,</mo> </mrow> </math> Wherein N is the magnitude of some or all of the selected rotation symbols; k is the value of the predetermined average power, and K > 0; saturating the final symbol; step two, determining each level of preset threshold of soft bit demodulation of M-element orthogonal amplitude modulation to obtain a preset average power value, wherein the value M of M in the M-element orthogonal amplitude modulation is 2^2*PP in the index is a positive integer; and determining the shortest distance a from the position of the rotation symbol to the coordinate axis, wherein the calculation formula of each level of threshold bound _ p is as follows: $\mathrm{boutd}\_p=a*2^{P-p}*\sqrt{K},$ wherein, P is 1, 2., P-1; the bits of the final symbol obtained by calculating the ith symbol according to the threshold are respectively as follows:

$b_i\left(1\right)=\mathrm{real}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(2\right)=\mathrm{imag}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

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|

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b_i(2P-1)＝bound_(P-1)p-|b_i(2P-3)|

b_i(2P)＝bound_(P-1)-|b_i(2P-2)|。

the method, wherein the mapping the received symbols in the first step further includes: step A, judging if the phase adjustment needs to be carried out on the received symbol, firstly carrying out the phase adjustment on the symbol to obtain a rotating symbol, and turning to the step B; otherwise, directly turning to the step B; and B, adjusting the amplitude of the rotating symbol or the received symbol according to the preset average power to obtain a final symbol.

The method, when the method is applied to 16-ary qam demodulation in TD-SCDMA, the phase adjusting the received symbols further comprises: clockwise rotating the constellation diagram by 45 degrees to form a rectangular diagram under a rectangular plane coordinate system; adjusting the phase of the rotation sign to obtain a rotation sign; and the rotation symbol is obtained by adopting the following method: rotateReal part of symbol: $\mathrm{real}\left({\hat{d}}_{\mathrm{rot}}\right)=\mathrm{real}\left(\hat{d}\right)+\mathrm{imag}\left(\hat{d}\right),$ imaginary part of the rotation sign: $\mathrm{imag}\left({\hat{d}}_{\mathrm{rot}}\right)=\mathrm{imag}\left(\hat{d}\right)-\mathrm{real}\left(\hat{d}\right),$ wherein,

is the symbol that was received and is,is a sign of the rotation of the rotary shaft,

is the real part of the received symbol,

is the real part of the rotated symbol,

is the imaginary part of the received symbol and,

is the rotated sign imaginary part.

The method, wherein, in the step B, the final symbol is obtained by adjusting the amplitude of the rotation symbol according to the predetermined average power

According to the following method: <math> <mrow> <msub> <mover> <mi>d</mi> <mo>^</mo> </mover> <mi>norm</mi> </msub> <mo>=</mo> <mrow> <mo>(</mo> <msqrt> <mi>K</mi> </msqrt> <mo>/</mo> <msqrt> <mrow> <mo>(</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>N</mi> </munderover> <msup> <mrow> <mo>|</mo> <mo>|</mo> <msub> <mover> <mi>d</mi> <mo>^</mo> </mover> <mi>rot</mi> </msub> <mrow> <mo>(</mo> <mi>i</mi> <mo>)</mo> </mrow> <mo>|</mo> <mo>|</mo> </mrow> <mn>2</mn> </msup> <mo>)</mo> </mrow> <mo>/</mo> <mi>N</mi> </msqrt> <mo>)</mo> </mrow> <mo>&times;</mo> <msub> <mover> <mi>d</mi> <mo>^</mo> </mover> <mi>rot</mi> </msub> </mrow> </math> wherein N is the magnitude of some or all of the selected rotation symbols; said K is the number of said predetermined average powerAnd K > 0.

The method, wherein the obtaining of the final symbolThen, the final symbol is further processed

A saturation operation comprising: if the final symbol

Is greater than real or imaginary partThen the saturation is

If the final symbol

Is less than the real or imaginary part

Then the saturation is

The method, wherein if the value K of the predetermined average power is 1, the final symbol is determined to be the last symbolIf the real part or the imaginary part of (b) is greater than 1, the saturation is 1; if the final symbol

Is less than-1, the saturation is-1.

The above-mentioned process, wherein,in the second step, the predetermined threshold is obtained according to the following method: obtaining a predetermined average power value, wherein M in M-ary quadrature amplitude modulation is 2^2*PP in the index is a positive integer; determining the shortest distance a from the position of the rotating symbol on the constellation diagram to the coordinate axis, wherein the calculation formula of each level of threshold bound _ p is as follows: $\mathrm{bound}\_p=a*2^{P-p}*\sqrt{K},$ wherein, P is 1, 2., P-1; the bits obtained by calculating the ith symbol according to the threshold are respectively:

$b_i\left(1\right)=\mathrm{real}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(2\right)=\mathrm{imag}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

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b_i(2P-1)＝bound_(P-1)p-|b_i(2P-3)|

b_i(2P)＝bound_(P-1)-|b_i(2P-2)|。

in the above method, after calculating each bit of the final symbol in the second step, the method further includes: adopting hard bit demodulation to directly judge the obtained value, and carrying out judgment on the b_i(1) To b_i(2P) if the value is not less than 0, the value is judged to be 0, and if the value is less than 0, the value is judged to be 1; or b is the same as_i(1) To b_iThe value of (2P) is 1 when it is 0 or more and 0 when it is less than 0.

The above method, wherein when M is 16, P is 2, then P is 1; $a=1/\sqrt{10},$ according to the calculation formula $\mathrm{bound}\_p=a*2^{P-p}*\sqrt{K},$ To obtain $\mathrm{bound}\_1=\sqrt{2K/5};$ Soft bit demodulation for 16-ary quadrature amplitude modulation is as follows:

$b_i\left(1\right)=\mathrm{real}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(2\right)=\mathrm{imag}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(3\right)=\mathrm{bound}\_1-\left|b_i\left(1\right)\right|=\sqrt{2K/5}-\left|b_i\left(1\right)\right|$

$b_i\left(4\right)=\mathrm{bound}\_1-\left|b_i\left(2\right)\right|=\sqrt{2K/5}-\left|b_i\left(2\right)\right|;$

when M is 64, P is 3, then P is 1 or 2; $a=1/\sqrt{42}$ according to the calculation formula $\mathrm{bound}\_p=a*2^{P-p}*\sqrt{K},$ To obtain $\mathrm{bound}\_1=\sqrt{8K/21},$ $\mathrm{bound}\_2=\sqrt{2K/21};$ For 64-ary quadrature amplitude modulationThe soft bit demodulation of (a) is as follows:

$b_i\left(1\right)=\mathrm{real}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(2\right)=\mathrm{imag}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(3\right)=\mathrm{bound}\_1-\left|b_i\left(1\right)\right|=\sqrt{8K/21}-\left|b_i\left(1\right)\right|$

$b_i\left(4\right)=\mathrm{bound}\_1-\left|b_i\left(2\right)\right|=\sqrt{8K/21}-\left|b_i\left(2\right)\right|$

$b_i\left(5\right)=\mathrm{bound}\_2-\left|b_i\left(3\right)\right|=\sqrt{2K/21}-\left|b_i\left(3\right)\right|$

$b_i\left(6\right)=\mathrm{bound}\_2-\left|b_i\left(4\right)\right|=\sqrt{2K/21}-\left|b_i\left(4\right)\right|;$

when M is 256, P is 4, then P is 1, 2 or 3; $a=1/\sqrt{170}$ according to the calculation formula $\mathrm{bound}\_p=a*2^{P-p}*\sqrt{K},$ To obtain $\mathrm{bound}\_1=\sqrt{32K/85},$ $\mathrm{bound}\_2=\sqrt{8K/85},$ $\mathrm{bound}\_3=\sqrt{2K/85};$ The soft bit demodulation for 256-ary quadrature amplitude modulation is as follows:

$b_i\left(1\right)=\mathrm{real}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(2\right)=\mathrm{imag}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(3\right)=\mathrm{bound}\_1-\left|b_i\left(1\right)\right|=\sqrt{32K/85}-\left|b_i\left(1\right)\right|$

$b_i\left(4\right)=\mathrm{bound}\_1-\left|b_i\left(2\right)\right|=\sqrt{32K/85}-\left|b_i\left(2\right)\right|$

$b_i\left(5\right)=\mathrm{bound}\_2-\left|b_i\left(3\right)\right|=\sqrt{8K/85}-\left|b_i\left(3\right)\right|$

$b_i\left(6\right)=\mathrm{bound}\_2-\left|b_i\left(4\right)\right|=\sqrt{8K/85}-\left|b_i\left(4\right)\right|$

$b_i\left(7\right)=\mathrm{bound}\_3-\left|b_i\left(5\right)\right|=\sqrt{2K/85}-\left|b_i\left(5\right)\right|$

$b_i\left(8\right)=\mathrm{bound}\_3-\left|b_i\left(6\right)\right|=\sqrt{2K/85}-\left|b_i\left(6\right)\right|.$

the above method, wherein the calculation formula $\mathrm{bound}\_p=a*2^{P-p}*\sqrt{K}$ When the value K of the predetermined average power is 1: for soft bit demodulation of 16-ary quadrature amplitude modulation, $\mathrm{bound}\_1=\sqrt{2/5},$ then:

$b_i\left(1\right)=\mathrm{real}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(2\right)=\mathrm{imag}\left({\hat{d}}_{\mathrm{nrom}}\left(i\right)\right)$

$b_i\left(3\right)=\sqrt{2/5}-\left|b_i\left(1\right)\right|$

$b_i\left(4\right)=\sqrt{2/5}-\left|b_i\left(2\right)\right|;$

for soft bit demodulation of 64-ary quadrature amplitude modulation, $\mathrm{bound}\_1=\sqrt{8/21},$ $\mathrm{bound}\_2=\sqrt{2/21},$ then:

$b_i\left(1\right)=\mathrm{real}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(2\right)=\mathrm{imag}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(3\right)=\sqrt{8/21}-\left|b_i\left(1\right)\right|$

$b_i\left(4\right)=\sqrt{8/21}-\left|b_i\left(2\right)\right|$

$b_i\left(5\right)=\sqrt{2/21}-\left|b_i\left(3\right)\right|$

$b_i\left(6\right)=\sqrt{2/21}-\left|b_i\left(4\right)\right|;$

for soft bit demodulation of 256-ary quadrature amplitude modulation, $\mathrm{bound}\_1=\sqrt{32/85},$ $\mathrm{bound}\_2=\sqrt{8/85},$ $\mathrm{bound}\_3=\sqrt{2/85},$ then:

$b_i\left(1\right)=\mathrm{real}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(2\right)=\mathrm{imag}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(3\right)=\sqrt{32/85}-\left|b_i\left(1\right)\right|$

$b_i\left(4\right)=\sqrt{32/85}-\left|b_i\left(2\right)\right|$

$b_i\left(5\right)=\sqrt{8/85}-\left|b_i\left(3\right)\right|$

$b_i\left(6\right)=\sqrt{8/85}-\left|b_i\left(4\right)\right|$

$b_i\left(7\right)=\sqrt{2/85}-\left|b_i\left(5\right)\right|$

$b_i\left(8\right)=\sqrt{2/85}-\left|b_i\left(6\right)\right|.$

a quadrature amplitude modulation and demodulation device applied to a communication system comprises a symbol preprocessing module and a quadrature amplitude modulation and demodulation module; the symbol preprocessing module comprises a phase adjusting unit, an amplitude adjusting unit and a saturation correcting unit, and the three units are electrically connected in sequence; the phase adjusting unit is used for adjusting the constellation diagram into a rectangular diagram under a plane rectangular coordinate system; adjusting the received symbols to the corresponding positions of rectangular diagrams of which the constellation diagrams are positioned under a plane rectangular coordinate system; the amplitude adjusting unit adjusts the amplitude of the rotation symbol corresponding to the symbol according to the preset average power to obtain the final symbol

<math> <mrow> <msub> <mover> <mi>d</mi> <mo>^</mo> </mover> <mi>norm</mi> </msub> <mo>=</mo> <mrow> <mo>(</mo> <msqrt> <mi>K</mi> </msqrt> <mo>/</mo> <msqrt> <mrow> <mo>(</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>N</mi> </munderover> <msup> <mrow> <mo>|</mo> <mo>|</mo> <msub> <mover> <mi>d</mi> <mo>^</mo> </mover> <mi>rot</mi> </msub> <mrow> <mo>(</mo> <mi>i</mi> <mo>)</mo> </mrow> <mo>|</mo> <mo>|</mo> </mrow> <mn>2</mn> </msup> <mo>)</mo> </mrow> <mo>/</mo> <mi>N</mi> </msqrt> <mo>)</mo> </mrow> <mo>&times;</mo> <msub> <mover> <mi>d</mi> <mo>^</mo> </mover> <mi>rot</mi> </msub> <mo>,</mo> </mrow> </math> Wherein N is the magnitude of some or all of the selected rotation symbols; k is the value of the predetermined average power, and K > 0; the saturation correction unit performs saturation operation on the final symbol; the quadrature amplitude modulation and demodulation module is used for determining each level of preset threshold of the soft bit demodulation method of M-ary quadrature amplitude modulation and obtaining a preset average power value, wherein the value M of M in the M-ary quadrature amplitude modulation is 2^2*PP in the index is a positive integer; and determining the shortest distance a from the position of the rotation symbol to the coordinate axis, wherein the calculation formula of each level of threshold bound _ p is as follows: $\mathrm{bound}\_p=a*2^{P-p}*\sqrt{K},$ wherein, P is 1, 2., P-1; the bits of the final symbol obtained by calculating the ith symbol according to the threshold are respectively as follows:

$b_i\left(1\right)=\mathrm{real}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(2\right)=\mathrm{imag}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

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|

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b_i(2P-1)＝bound_(P-1)p-|b_i(2P-3)|

b_i(2P)＝bound_(P-1)-|b_i(2P-2)|。

the above device, wherein when the device is applied to 16-ary quadrature amplitude modulation and demodulation in TD-SCDMA, the phase adjusting unit rotates the constellation diagram clockwise by 45 degrees into a rectangular diagram under a rectangular plane coordinate system; adjusting the phase of the received symbol to a corresponding position in a rectangular graph under the rectangular coordinate system after the symbol rotates clockwise by 45 degrees; the phase adjustment unit of the symbol preprocessing module calculates the rotation symbol according to the following formula

Real part of

Imaginary part

$\mathrm{real}\left({\hat{d}}_{\mathrm{rot}}\right)=\mathrm{real}\left(\hat{d}\right)+\mathrm{imag}\left(\hat{d}\right)$

$\mathrm{imag}\left({\hat{d}}_{\mathrm{rot}}\right)=\mathrm{imag}\left(\hat{d}\right)-\mathrm{real}\left(\hat{d}\right);$

And rotating the symbol

And real part

Imaginary part

And sending the data to an amplitude adjusting unit.

The apparatus above, wherein the qam/qam module obtains a predetermined average power value K, and the value M of M in M-ary qam is 2^2*PCalculating a positive integer P; determining the shortest distance a from the position of the rotating symbol on the constellation diagram to the coordinate axis; according to the formula $\mathrm{bound}\_p=a*2^{P-p}*\sqrt{K}$ The values of the fixed thresholds bound _1, bound _2.. round _ (P-1) of each stage are determined, where P1, 2.., P-1.

The above apparatus, wherein the obtaining of each bit from the final symbol output by the saturation correction unit further includes: adopting a hard bit demodulation method to directly judge the acquired value, and carrying out the judgment on the b_i(1) To b_i(2P) if the value is not less than 0, the value is judged to be 0, and if the value is less than 0, the value is judged to be 1; or b is the same as_i(1) To b_iThe value of (2P) is 1 when it is 0 or more and 0 when it is less than 0.

The apparatus above, wherein the qam/qam module demodulates qam with gray code characteristics according to a preset setting, and supports at least 16-ary qam/qam, 64-ary qam/qam, or 256-ary qam/qam.

The quadrature amplitude modulation and demodulation method and device applied to the communication system provided by the invention have the following steps that firstly, a receiving end adopts a constellation diagram to map a received symbol to obtain a final symbol of the symbol, and the final symbol is subjected to saturation operation; and step two, determining each level of preset threshold of soft bit demodulation of M-element quadrature amplitude modulation, and calculating each bit of the final symbol according to the preset threshold and the final symbol after saturation operation. The block error rate of the receiving end is greatly reduced, the data transmission efficiency of the network is improved, and meanwhile, the data transmission efficiency is improved because the demodulation operation is simpler.

Drawings

Fig. 1 is a 16-ary qam constellation according to an embodiment of the present invention;

fig. 2 is a process diagram of a 16-ary qam demodulation method according to an embodiment of the present invention;

fig. 3 is a schematic diagram of 16-ary qam-demod constellation conversion according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a 16-ary QAM/QAM apparatus according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of mapping 64-ary QAM constellation in the present invention;

fig. 6 is a schematic diagram of the qam demodulation method applied to a communication system according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and implementation effects of the present invention clearer, the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The invention provides a method and a device for quadrature amplitude modulation and demodulation in a communication system, which can be widely applied to different communication technologies in the communication field, and the specific technical scheme of the invention is described below by taking 16QAM adopted in TD-SCDMA standard in the mobile communication field as an embodiment. Table 1 is a 16QAM constellation mapping relationship defined in the 3GPP R525.223 protocol, where each 4 bits corresponds to a symbol, where a symbol is a complex symbol, and the real part of the symbol is also referred to as I-path and the imaginary part is also referred to as Q-path; by representing the bit-symbol mapping relationship reflected in table 1 in a rectangular plane coordinate system, as shown in fig. 1, the constellation diagram of 16QAM is in the shape of a diamond, and the internal angle of the diamond is 90 °. The value ranges of the I path and the Q path of the 16QAM symbol are all

Table 116 QAM constellation mapping table

Fig. 2 shows a 16QAM process in TD-SCDMA, which comprises the following specific steps:

step 201, firstly, the transmitting terminal encodes the bit stream, the encoded bit stream is sequentially divided into a plurality of groups, and each 4 continuous bits form one group.

Step 202, each group is mapped to a symbol according to the constellation diagram shown in fig. 1, for example, 1101 may be mapped to

I.e. way I is

Q path is

And 203, forming data of the physical code channel at the transmitting end by the symbol, and transmitting the data to an antenna end through a radio frequency circuit to form a transmitting signal.

Step 204, the transmitting signal reaches a receiving end antenna through an air wireless channel, such as a 3GPP channel; as shown in fig. 6, the signal is received at the rf front end of the receiving end, and the signal is subjected to rf down-conversion and baseband processing, and then data demodulation to obtain a digital signal.

Step 205, the digital signal is demodulated by the symbol demodulator as shown in fig. 6 to obtain the required symbolThe symbol demodulator may be a joint detector or other symbol demodulator.

Step 206. Data Communication Channel (DCC) passes the Data symbols through the QAM demodulator, each symbol

Demodulating into four bits, connecting the demodulated bits in sequence to form a bit stream, and sending the bit stream to a bit decoder through a quantizer as shown in fig. 6, so as to obtain bit information required by a user; the demodulator of the QAM adopts the method or the device provided by the invention.

As can be seen from fig. 6, after the rf front end of the receiving end receives the signal of the transmitting end, the signal is processed by rf down-conversion and baseband, and then is demodulated by data to obtain a digital signal, the digital signal is demodulated by the QAM demodulator, all demodulated bits are connected in sequence to form a bit stream, and the bit stream is sent to the bit decoder by the quantizer, so that the required user information bit can be obtained finally. The demodulator demodulation process of QAM of the embodiment of the present invention comprises the following two main steps, wherein, the symbol

The symbol before the clockwise rotation is indicated,

the symbol rotation after clockwise rotation is shown, and without loss of generality, 16QAM is taken as an example for description.

Step one, preprocessing data;

as shown in FIG. 3, (1) first, phase adjustment is performed to obtain a symbol

In which the constellation diagram is rotated by 45 degrees clockwise, i.e. for symbols

Rotated 45 degrees clockwise, i.e. to the symbolMultiplication by e^-jπ/4Due to said <math> <mrow> <msup> <mi>e</mi> <mrow> <mo>-</mo> <mi>j&pi;</mi> <mo>/</mo> <mn>4</mn> </mrow> </msup> <mo>=</mo> <mi>cos</mi> <mrow> <mo>(</mo> <mi>&pi;</mi> <mo>/</mo> <mn>4</mn> <mo>)</mo> </mrow> <mo>-</mo> <mi>j</mi> <mi>sin</mi> <mrow> <mo>(</mo> <mi>&pi;</mi> <mo>/</mo> <mn>4</mn> <mo>)</mo> </mrow> <mo>=</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>-</mo> <mi>j</mi> <mo>)</mo> </mrow> <mo>/</mo> <msqrt> <mn>2</mn> </msqrt> <mo>,</mo> </mrow> </math> So symbol

And e^-jπ/4Product of (2)

Is still a symbol of complex form

The

Hereinafter referred to as a rotation symbol, of

Real part of

Imaginary part

The method can be obtained by the addition and subtraction operation in the following way:

$\mathrm{real}\left({\hat{d}}_{\mathrm{rot}}\right)=\mathrm{real}\left(\hat{d}\right)+\mathrm{imag}\left(\hat{d}\right)$

$\mathrm{imag}\left({\hat{d}}_{\mathrm{rot}}\right)=\mathrm{imag}\left(\hat{d}\right)-\mathrm{real}\left(\hat{d}\right)$

(2) secondly, the rotating symbol

Carrying out amplitude adjustment, namely carrying out power normalization on the symbol after phase adjustment to obtain a final symbol

If normalized to a certain real value K, the real value K describes a specific value of the power.

First, all or part of the rotation symbol is calculatedAverage power ofWherein i is the subscript or serial number corresponding to the ith symbol, and then the reciprocal is obtained

Finally multiplied by the rotation sign

To obtainWhere N represents the number of said full or partial rotation symbols. In the embodiment of the invention, because the amplitude adjustment processing is carried out on the symbol after the phase rotation, namely the symbol is normalized to a real power adjustment value K, the obtained final symbol

The method comprises the following steps: <math> <mrow> <msub> <mover> <mi>d</mi> <mo>^</mo> </mover> <mi>norm</mi> </msub> <mo>=</mo> <mrow> <mo>(</mo> <msqrt> <mi>K</mi> </msqrt> <mo>/</mo> <msqrt> <mrow> <mo>(</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>N</mi> </munderover> <msup> <mrow> <mo>|</mo> <mo>|</mo> <msub> <mover> <mi>d</mi> <mo>^</mo> </mover> <mi>rot</mi> </msub> <mrow> <mo>(</mo> <mi>i</mi> <mo>)</mo> </mrow> <mo>|</mo> <mo>|</mo> </mrow> <mn>2</mn> </msup> <mo>)</mo> </mrow> <mo>/</mo> <mi>N</mi> </msqrt> <mo>)</mo> </mrow> <mo>&times;</mo> <msub> <mover> <mi>d</mi> <mo>^</mo> </mover> <mi>rot</mi> </msub> <mo>,</mo> </mrow> </math> wherein,

representing the final sign after the phase rotation and amplitude adjustment processing, wherein N used for calculating the average power of the rotation sign satisfies, <math> <mrow> <mn>1</mn> <mo>&le;</mo> <mi>N</mi> <mo>&le;</mo> <mi>length</mi> <mrow> <mo>(</mo> <mover> <mi>d</mi> <mo>^</mo> </mover> <mo>)</mo> </mrow> <mo>,</mo> </mrow> </math> wherein,

representing all symbols to be processed

And N adopts an integer power of 2 as much as possible, so that the receiving end reduces the complexity of calculation.

After the power normalization process, some final symbols may appear

Real part of

Or imaginary part

Is greater than

Or less than

And performing saturation processing on the real parts or the imaginary parts. The saturation process will be whatever the real part of the final symbol

Or imaginary part

Is greater than

Is uniformly saturated by

All is the real part

Or imaginary part

Is less thanIs uniformly saturated by

For example, when K is 1, $\sqrt{K}=1$ and is $-\sqrt{K}=-1,$ The 1.23 saturation treatment is 1 and the-1.05 saturation treatment is-1.

Step two, for the final symbol

Performing 16QAM, or 64QAM, or 256 QAM; the methods of demodulation generally include two types: soft Bit (Bit) demodulation, hard Bit (Bit) demodulation.

Soft bit demodulationThe method is as follows, wherein b_i(1) To b_i(2P) then respectively represent the first bit to the 2P bit of the ith final symbol:

firstly, determining values of fixed thresholds bound _1 and bound _2.. round.. bound _ (P-1) of each level, wherein the values of the fixed thresholds of each level are only related to a specific QAM constellation diagram and a preset amplitude adjustment value K, and on the constellation diagram with the amplitude adjustment value K being 1, the shortest distance from a standard position of a symbol to a coordinate axis is a, then the fixed thresholds bound _ P of each level are calculated as follows: $\mathrm{bound}\_p=a*2^{P-p}*\sqrt{K},$ wherein P is 1, 2, 1, and P is a lower case letter and P is an upper case letter.

For M-16 quadrature amplitude modulation, $a=1/\sqrt{10},$ according to the formula M-2^2*PTo obtain P ═ 2, then $\mathrm{bound}\_1=\sqrt{2K/5};$ In the 16QAM method in TD-SCDMA according to the embodiment of the present invention, since the amplitude adjustment value K is 1, it is obvious that $\mathrm{bound}\_1=\sqrt{2/5}.$

When the embodiment of the invention is applied to a non-TD-SCDMA communication system, ifIf 64-ary quadrature amplitude modulation is required, then for M-64-ary quadrature amplitude modulation, the value is taken $a=1/\sqrt{42},$ According to the formula M-2^2*PGet P to 3, as shown in fig. 5, there are two fixed thresholds, then $\mathrm{bound}\_1=\sqrt{8K/21},$ $\mathrm{bound}+2=\sqrt{2K/21},$ The fixed threshold identified in the figure is the value when K is 1, and the value of b1b2 is consistent in each quadrant, so only the value of b3b4 b5b6 is identified in fig. 5.

When the embodiment of the invention is applied to a non-TD-SCDMA communication system, if 64-element quadrature amplitude modulation is required, for M-256-element quadrature amplitude modulation, the M-256-element quadrature amplitude modulation is selected $a=1/\sqrt{170},$ According to the formula M-2^2*PTo get P to 4, there are three fixed thresholds:

then $\mathrm{bound}\_1=\sqrt{32K/85},$

$\mathrm{bound}\_2=\sqrt{8K/85},$

$\mathrm{bound}\_3=\sqrt{2K/85}.$

After determining the respective fixed threshold, for soft bit demodulation using gray coded M-ary quadrature amplitude modulation, the respective bit of each final symbol is calculated using the following method:

the value of M in the M-element quadrature amplitude modulation is as follows: m2^2*PWherein P in the index is a positive integer, and in the formula, P1, 2

$b_i\left(1\right)=\mathrm{real}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(2\right)=\mathrm{imag}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

|

|

|

b_i(2P-1)＝bound_(P-1)p-|b_i(2P-3)|

b_i(2P)＝bound_(P-1)-|b_i(2P-2)|

The value obtained by the above formula is not usually an integer of 0 or 1, but is a decimal value, wherein | b in the formula_i(2P-2)|、|b_i(2P-3) | denotes the operation of taking the absolute value of a real number.

When M is 16, P is 2, then P is 1; soft bit demodulation for 16-ary quadrature amplitude modulation is as follows:

$b_i\left(1\right)=\mathrm{real}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(2\right)=\mathrm{imag}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(3\right)=\mathrm{bound}\_1-\left|b_i\left(1\right)\right|=\sqrt{2K/5}-\left|b_i\left(1\right)\right|$

$b_i\left(4\right)=\mathrm{bound}\_1-\left|b_i\left(2\right)\right|=\sqrt{2K/5}-\left|b_i\left(2\right)\right|$

when M is 64, P is 3, then P is 1, 2; the soft bit demodulation for 64-ary quadrature amplitude modulation is as follows:

$b_i\left(1\right)=\mathrm{real}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(2\right)=\mathrm{imag}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(3\right)=\mathrm{bound}\_1-\left|b_i\left(1\right)\right|=\sqrt{8K/21}-\left|b_i\left(1\right)\right|$

$b_i\left(4\right)=\mathrm{bound}\_1-\left|b_i\left(2\right)\right|=\sqrt{8K/21}-\left|b_i\left(2\right)\right|$

$b_i\left(5\right)=\mathrm{bound}\_2-\left|b_i\left(3\right)\right|=\sqrt{2K/21}-\left|b_i\left(3\right)\right|$

$b_i\left(6\right)=\mathrm{bound}\_2-\left|b_i\left(4\right)\right|=\sqrt{2K/21}-\left|b_i\left(4\right)\right|$

when M is 256, P is 4, then P is 1, 2, 3; the soft bit demodulation for 256-ary quadrature amplitude modulation is as follows:

$b_i\left(1\right)=\mathrm{real}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(2\right)=\mathrm{imag}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(3\right)=\mathrm{bound}\_1-\left|b_i\left(1\right)\right|=\sqrt{32K/85}-\left|b_i\left(1\right)\right|$

$b_i\left(4\right)=\mathrm{bound}\_1-\left|b_i\left(2\right)\right|=\sqrt{32K/85}-\left|b_i\left(2\right)\right|$

$b_i\left(5\right)=\mathrm{bond}\_2-\left|b_i\left(3\right)\right|=\sqrt{8K/85}-\left|b_i\left(3\right)\right|$

$b_i\left(6\right)=\mathrm{bound}\_2-\left|b_i\left(4\right)\right|=\sqrt{8K/85}-\left|b_i\left(4\right)\right|$

$b_i\left(7\right)=\mathrm{bound}\_3-\left|b_i\left(5\right)\right|=\sqrt{2K/85}-\left|b_i\left(5\right)\right|$

$b_i\left(8\right)=\mathrm{bound}\_3-\left|b_i\left(6\right)\right|=\sqrt{2K/85}-\left|b_i\left(6\right)\right|$

the above describes the method using soft bit demodulation, and if the receiving end also uses the hard bit demodulation method, the value obtained by the soft bit demodulation method can be directly determined, taking fig. 5 as an example, for the b_i(1) To b_i(2P) taking an integer whenever the value falls within a predetermined certain range; for example, if the numerical value is 0 or more, it is determined as 0, and if it is less than 0, it is determined as 1; or if the numerical value is more than or equal to 0, the result is judged to be 1, and if the numerical value is less than 0, the result is judged to be 0; specifically, for example, the soft bit is 0.32, which can be judged as +1, and-0.04 can be judged as 0.

The hard bit demodulation method may be employed after the soft bit demodulation method, or only the hard bit demodulation method or only the soft bit demodulation method may be employed.

The invention also provides a device corresponding to the method, as shown in fig. 4, the device comprises: a symbol preprocessing module 401, a QAM demodulation module 405;

the preprocessing module is used for processing symbols

Carrying out pretreatment; in the TD-SCDMA communication system, the module rotates the constellation diagram of the received symbol clockwise by 45 degrees into a rectangular diagram under a rectangular plane coordinate system to obtain a rotating symbol; and adjusting the amplitude of the rotation symbol to a predetermined value according to the average power of the constellation to obtain a final symbol

And then performing saturation treatment. The preprocessing module comprises a phase adjusting unit 402, an amplitude adjusting unit 403 and a saturation correcting unit 404, which are electrically connected in sequence. Wherein the phase adjustment unit 404 aligns the symbols

Rotated 45 degrees clockwise, i.e. to the symbol

Multiplication by e^-jπ/4Due to said <math> <mrow> <msup> <mi>e</mi> <mrow> <mo>-</mo> <mi>j&pi;</mi> <mo>/</mo> <mn>4</mn> </mrow> </msup> <mo>=</mo> <mi>cos</mi> <mrow> <mo>(</mo> <mi>&pi;</mi> <mo>/</mo> <mn>4</mn> <mo>)</mo> </mrow> <mo>-</mo> <mi>j</mi> <mi>sin</mi> <mrow> <mo>(</mo> <mi>&pi;</mi> <mo>/</mo> <mn>4</mn> <mo>)</mo> </mrow> <mo>=</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>-</mo> <mi>j</mi> <mo>)</mo> </mrow> <mo>/</mo> <msqrt> <mn>2</mn> </msqrt> <mo>,</mo> </mrow> </math> So symbol

And e^-jπ/4Product of (2)

Is still a symbol of complex form

The symbol may be referred to as a rotated symbol, the real part of which

Imaginary part

The phase adjustment unit 404 obtains the following addition and subtraction operations:

$\mathrm{real}\left({\hat{d}}_{\mathrm{rot}}\right)=\mathrm{real}\left(\hat{d}\right)+\mathrm{imag}\left(\hat{d}\right)$

$\mathrm{imag}\left({\hat{d}}_{\mathrm{rot}}\right)=\mathrm{imag}\left(\hat{d}\right)-\mathrm{real}\left(\hat{d}\right)$

the phase adjustment unit 404 obtains the rotation symbol

And real part

Imaginary partSent to an amplitude adjustment unit 403, the amplitude adjustment unit 403 is used to adjust the symbol

Amplitude adjustment, i.e. calculating the average power of the rotated sequenceThen, the reciprocal of the value is obtained

Finally multiplying by the rotated symbol sequence to obtainIn the invention, the data after phase rotation is normalized to a real value K representing power by carrying out power normalization processing, so that the obtained final symbolThe method comprises the following steps: <math> <mrow> <msub> <mover> <mi>d</mi> <mo>^</mo> </mover> <mi>norm</mi> </msub> <mo>=</mo> <mrow> <mo>(</mo> <msqrt> <mi>K</mi> </msqrt> <mo>/</mo> <msqrt> <mrow> <mo>(</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>N</mi> </munderover> <msup> <mrow> <mo>|</mo> <mo>|</mo> <msub> <mover> <mi>d</mi> <mo>^</mo> </mover> <mi>rot</mi> </msub> <mrow> <mo>(</mo> <mi>i</mi> <mo>)</mo> </mrow> <mo>|</mo> <mo>|</mo> </mrow> <mn>2</mn> </msup> <mo>)</mo> </mrow> <mo>/</mo> <mi>N</mi> </msqrt> <mo>)</mo> </mrow> <mo>&times;</mo> <msub> <mover> <mi>d</mi> <mo>^</mo> </mover> <mi>rot</mi> </msub> <mo>,</mo> </mrow> </math> wherein,

which represents the sign after phase rotation and normalization of the power, where N is satisfied for calculating the average power of the sequence, <math> <mrow> <mn>1</mn> <mo>&le;</mo> <mi>N</mi> <mo>&le;</mo> <mi>length</mi> <mrow> <mo>(</mo> <mover> <mi>d</mi> <mo>^</mo> </mover> <mo>)</mo> </mrow> <mo>.</mo> </mrow> </math> here, N is an integer power of 2 as much as possible, so as to facilitate calculation and reduce implementation complexity. Symbol after power normalization processingThe phase adjustment unit 404 sends the phase adjustment unit 404 to the saturation correction unit 404.

The saturation correction unit 404 after normalization for saturation correction

For those real parts

Or imaginary part

Is greater thanOr less than

Is saturated, i.e. the real part

Or imaginary part

Is greater thanIs uniformly saturated and corrected to

Will partOr imaginary partIs less than

Is uniformly saturated and corrected to

The saturation correction unit 404 is connected to the QAM demodulation module 405.

The QAM demodulation module 405 is configured to demodulate and support at least 16QAM, 64QAM, 256 QAM; the methods of demodulation generally include two types: soft bit demodulation method, hard bit demodulation method.

In the soft bit demodulation method, the value of each fixed threshold bound _ p is determined first, the value of the threshold is only related to a specific QAM constellation diagram and a predetermined amplitude adjustment value K, as shown in fig. 5, the shortest distance from the constellation diagram with the amplitude adjustment value K of 1 to the coordinate axis is a, and then each fixed threshold is determined $\mathrm{bound}\_p=a*2^{P-p}*\sqrt{K},$ Wherein P is 1, 2. In the embodiment of the present invention, for the 16QAM method in TD-SCDMA, if K is 1, it is obvious that $\mathrm{bound}\_1=\sqrt{2/5}.$ The specific implementation of M-16 quadrature amplitude modulation, M-64 quadrature amplitude modulation, and M-256 quadrature amplitude modulation is then the same as described in the method, and will not be described here in a repeated manner.

The QAM demodulation module 405 may select a module or a unit that supports M-16 quadrature amplitude modulation, M-64 quadrature amplitude modulation, and M-256 quadrature amplitude modulation. Meanwhile, the QAM demodulation module 405 provides a function of hard bit demodulation, and may directly determine the value obtained by the soft bit demodulation method, where b is_i(1) To b_i(2P) when the value falls within a certain range, e.g. for values greater than or equal toJudging the sample to be 0 if the sample is 0, and judging the sample to be 1 if the sample is less than 0; or if the numerical value is more than or equal to 0, the result is judged to be 1, and if the numerical value is less than 0, the result is judged to be 0; specifically, for example, the soft bit is 0.32, which can be judged as +1, and-0.04 can be judged as 0.

The hard bit demodulation method may be employed after the soft bit demodulation method, or only the hard bit demodulation method or the soft bit demodulation method may be employed.

The technical scheme described in the embodiment of the invention has simple demodulation process, wherein the symbol preprocessing process only comprises phase adjustment and amplitude adjustment, most of the symbol preprocessing process is addition operation, and the demodulation performance is good, thereby overcoming the defects of reduced network data transmission efficiency caused by the rapid increase of the block error rate of the receiving end and reduced data transmission efficiency caused by complex demodulation operation at the receiving end. And the technical problems solved by the technical scheme of the invention generally exist in the communication field, so the technical scheme of the invention can be applied in various communication fields.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting, and all the values of the parameters can be adjusted according to the actual situation and are within the scope of the claims. It will be understood by those skilled in the art that various modifications and equivalent arrangements may be made without departing from the spirit and scope of the present invention and shall be covered by the appended claims.

Claims (12)

1. A qam demodulation method applied to a communication system, comprising the steps of:

step one, the receiving end adopts the constellation diagram to map the received symbols,

adjusting the amplitude of the rotation symbol corresponding to the symbol according to the preset average power to obtain the final symbol

<math> <mrow> <msub> <mover> <mi>d</mi> <mo>^</mo> </mover> <mi>norm</mi> </msub> <mo>=</mo> <mrow> <mo>(</mo> <msqrt> <mi>K</mi> </msqrt> <mo>/</mo> <msqrt> <mrow> <mo>(</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>N</mi> </munderover> <msup> <mrow> <mo>|</mo> <mo>|</mo> <msub> <mover> <mi>d</mi> <mo>^</mo> </mover> <mi>rot</mi> </msub> <mrow> <mo>(</mo> <mi>i</mi> <mo>)</mo> </mrow> <mo>|</mo> <mo>|</mo> </mrow> <mn>2</mn> </msup> <mo>)</mo> </mrow> <mo>/</mo> <mi>N</mi> </msqrt> <mo>)</mo> </mrow> <mo>&times;</mo> <msub> <mover> <mi>d</mi> <mo>^</mo> </mover> <mi>rot</mi> </msub> <mo>,</mo> </mrow> </math> Wherein N is the magnitude of some or all of the selected rotation symbols; k is the value of the predetermined average power, and K > 0; saturating the final symbol;

step two, determining each level of preset threshold of soft bit demodulation of M-element orthogonal amplitude modulation to obtain a preset average power value, wherein the value M of M in the M-element orthogonal amplitude modulation is 2^2*PP in the index is a positive integer; and determining the shortest distance a from the position of the rotation symbol to the coordinate axis, wherein the calculation formula of each level of threshold bound _ p is as follows: $\mathrm{bound}\_p=a*2^{P-p}*\sqrt{K},$ wherein, P is 1, 2., P-1;

the bits of the final symbol obtained by calculating the ith symbol according to the threshold are respectively as follows:

$b_i\left(1\right)=\mathrm{real}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(2\right)=\mathrm{imag}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

|

|

|

b_i(2P-1)＝bound_(P-1)p-|b_i(2P-3)|

b_i(2P)＝bound_(P-1)-|b_i(2P-2)|。

2. the method of claim 1, wherein said mapping the received symbols in step one further comprises:

if it is determined that phase adjustment is required for the received symbol, the symbol is first phase adjusted to obtain a rotated symbol.

3. The method of claim 2, wherein when the method is applied to 16-ary quadrature amplitude modulation and demodulation in TD-SCDMA, the phase adjusting the received symbols further comprises:

clockwise rotating the constellation diagram by 45 degrees to form a rectangular diagram under a rectangular plane coordinate system; adjusting the phase of the rotation sign to obtain a rotation sign; and the rotation symbol is obtained by adopting the following method:

real part of the rotation sign: $\mathrm{real}\left({\hat{d}}_{\mathrm{rot}}\right)=\mathrm{real}\left(\hat{d}\right)+\mathrm{imag}\left(\hat{d}\right),$

imaginary part of the rotation sign: $\mathrm{imag}\left({\hat{d}}_{\mathrm{rot}}\right)=\mathrm{imag}\left(\hat{d}\right)-\mathrm{real}\left(\hat{d}\right),$ wherein,is the symbol that was received and is,is a sign of the rotation of the rotary shaft,is the real part of the received symbol,

is the real part of the rotated symbol,

is the imaginary part of the received symbol and,

is the rotated sign imaginary part.

4. The method of claim 1, wherein the obtaining the final symbol

Then, the final symbol is further processed

A saturation operation comprising:

if the final symbol

Is greater than real or imaginary part

Then the saturation is

If the final characterNumber (C)Is less than the real or imaginary part

Then the saturation is

5. The method of claim 4, wherein if the value of the predetermined average power K is 1, then the final symbol is selected

If the real part or the imaginary part of (b) is greater than 1, the saturation is 1;

if the final symbol

Is less than-1, the saturation is-1.

6. The method of claim 1, wherein the step two, after calculating the bits of the final symbol, further comprises:

adopting hard bit demodulation to directly judge the obtained value, and carrying out judgment on the b_i(1) To b_i(2P) if the value is not less than 0, the value is judged to be 0, and if the value is less than 0, the value is judged to be 1; or b is the same as_i(1) To b_iThe value of (2P) is 1 when it is 0 or more and 0 when it is less than 0.

7. The method of claim 1, wherein when M is 16, P is 2, then P is 1; $a=1/\sqrt{10},$ according to the calculation formula $\mathrm{bound}\_p=a*2^{P-p}*\sqrt{K},$ To obtain $\mathrm{bound}\_1=\sqrt{2K/5};$ Soft bit demodulation for 16-ary quadrature amplitude modulation is as follows:

$b_i\left(1\right)=\mathrm{real}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(2\right)=\mathrm{imag}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(3\right)=\mathrm{bound}\_1-\left|b_i\left(1\right)\right|=\sqrt{2K/5}-\left|b_i\left(1\right)\right|$

$b_i\left(4\right)=\mathrm{bound}\_1-\left|b_i\left(2\right)\right|=\sqrt{2K/5}-\left|b_i\left(2\right)\right|;$

when M is 64, P is 3, then P is 1 or 2; $a=1/\sqrt{42}$ according to the calculation formula $\mathrm{bound}\_p=a*2^{P-p}*\sqrt{K},$ To obtain $\mathrm{bound}\_1=\sqrt{8K/21},$ $\mathrm{bound}\_2=\sqrt{2K/21};$ The soft bit demodulation for 64-ary quadrature amplitude modulation is as follows:

$b_i\left(1\right)=\mathrm{real}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(2\right)=\mathrm{imag}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(3\right)=\mathrm{bound}\_1-\left|b_i\left(1\right)\right|=\sqrt{8K/21}-\left|b_i\left(1\right)\right|$

$b_i\left(4\right)=\mathrm{bound}\_1-\left|b_i\left(2\right)\right|=\sqrt{8K/21}-\left|b_i\left(2\right)\right|$

$b_i\left(5\right)=\mathrm{bound}\_2-\left|b_i\left(3\right)\right|=\sqrt{2K/21}-\left|b_i\left(3\right)\right|$

$b_i\left(6\right)=\mathrm{bound}\_2-\left|b_i\left(4\right)\right|=\sqrt{2K/21}-\left|b_i\left(4\right)\right|;$

when M is 256, P is 4, then P is 1, 2 or 3; $a=1/\sqrt{170}$ according to the calculation formula $\mathrm{bound}\_p=a*2^{P-p}*\sqrt{K},$ To obtain $\mathrm{bound}\_1=\sqrt{32K/85},$ $\mathrm{bound}\_2=\sqrt{8K/85},$ $\mathrm{bound}\_3=\sqrt{2K/85};$ The soft bit demodulation for 256-ary quadrature amplitude modulation is as follows:

$b_i\left(1\right)=\mathrm{real}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(2\right)=\mathrm{imag}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(3\right)=\mathrm{bound}\_1-\left|b_i\left(1\right)\right|=\sqrt{32K/85}-\left|b_i\left(1\right)\right|$

$b_i\left(4\right)=\mathrm{bound}\_1-\left|b_i\left(2\right)\right|=\sqrt{32K/85}-\left|b_i\left(2\right)\right|$

$b_i\left(5\right)=\mathrm{bound}\_2-\left|b_i\left(3\right)\right|=\sqrt{8K/85}-\left|b_i\left(3\right)\right|$

$b_i\left(6\right)=\mathrm{bound}\_2-\left|b_i\left(4\right)\right|=\sqrt{8K/85}-\left|b_i\left(4\right)\right|$

$b_i\left(7\right)=\mathrm{bound}\_3-\left|b_i\left(5\right)\right|=\sqrt{2K/85}-\left|b_i\left(5\right)\right|$

$b_i\left(8\right)=\mathrm{bound}\_3-\left|b_i\left(6\right)\right|=\sqrt{2K/85}-\left|b_i\left(6\right)\right|.$

8. the method of claim 7, wherein the computational formula $\mathrm{bound}\_p=a*2^{P-p}*\sqrt{K}$ When the value K of the predetermined average power is 1:

for soft bit demodulation of 16-ary quadrature amplitude modulation, $\mathrm{bound}\_1=\sqrt{2/5},$ then:

$b_i\left(1\right)=\mathrm{real}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(2\right)=\mathrm{imag}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(3\right)=\sqrt{2/5}-\left|b_i\left(1\right)\right|$

$b_i\left(4\right)=\sqrt{2/5}-\left|b_i\left(2\right)\right|;$

for soft bit demodulation of 64-ary quadrature amplitude modulation, $\mathrm{bound}\_1=\sqrt{8/21},$ $\mathrm{bound}\_2=\sqrt{2/21},$ then:

$b_i\left(1\right)=\mathrm{real}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(2\right)=\mathrm{imag}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(3\right)=\sqrt{8/21}-\left|b_i\left(1\right)\right|$

$b_i\left(4\right)=\sqrt{8/21}-\left|b_i\left(2\right)\right|$

$b_i\left(5\right)=\sqrt{2/21}-\left|b_i\left(3\right)\right|$

$b_i\left(6\right)=\sqrt{2/21}-\left|b_i\left(4\right)\right|;$

for soft bit demodulation of 256-ary quadrature amplitude modulation, $\mathrm{bound}\_1=\sqrt{32/85},$ $\mathrm{bound}\_2=\sqrt{8/85},$ $\mathrm{bound}\_3=\sqrt{2/85},$ then:

$b_i\left(1\right)=\mathrm{real}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(2\right)=\mathrm{imag}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(3\right)=\sqrt{32/85}-\left|b_i\left(1\right)\right|$

$b_i\left(4\right)=\sqrt{32/85}-\left|b_i\left(2\right)\right|$

$b_i\left(5\right)=\sqrt{8/85}-\left|b_i\left(3\right)\right|$

$b_i\left(6\right)=\sqrt{8/85}-\left|b_i\left(4\right)\right|$

$b_i\left(7\right)=\sqrt{2/85}-\left|b_i\left(5\right)\right|$

$b_i\left(8\right)=\sqrt{2/85}-\left|b_i\left(6\right)\right|.$

9. a quadrature amplitude modulation and demodulation device applied to a communication system is characterized by comprising a symbol preprocessing module and a quadrature amplitude modulation and demodulation module;

the symbol preprocessing module comprises a phase adjusting unit, an amplitude adjusting unit and a saturation correcting unit, and the three units are electrically connected in sequence;

the phase adjusting unit is used for adjusting the constellation diagram into a rectangular diagram under a plane rectangular coordinate system; adjusting the received symbols to the corresponding positions of rectangular diagrams of which the constellation diagrams are positioned under a plane rectangular coordinate system;

the amplitude adjusting unit adjusts the amplitude of the rotation symbol corresponding to the symbol according to the preset average power to obtain the final symbol

<math> <mrow> <msub> <mover> <mi>d</mi> <mo>^</mo> </mover> <mi>norm</mi> </msub> <mo>=</mo> <mrow> <mo>(</mo> <msqrt> <mi>K</mi> </msqrt> <mo>/</mo> <msqrt> <mrow> <mo>(</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>N</mi> </munderover> <msup> <mrow> <mo>|</mo> <mo>|</mo> <msub> <mover> <mi>d</mi> <mo>^</mo> </mover> <mi>rot</mi> </msub> <mrow> <mo>(</mo> <mi>i</mi> <mo>)</mo> </mrow> <mo>|</mo> <mo>|</mo> </mrow> <mn>2</mn> </msup> <mo>)</mo> </mrow> <mo>/</mo> <mi>N</mi> </msqrt> <mo>)</mo> </mrow> <mo>&times;</mo> <msub> <mover> <mi>d</mi> <mo>^</mo> </mover> <mi>rot</mi> </msub> <mo>,</mo> </mrow> </math> Wherein N is the magnitude of some or all of the selected rotation symbols; k is the value of the predetermined average power, and K > 0;

the saturation correction unit performs saturation operation on the final symbol;

the quadrature amplitude modulation and demodulation module is used for determining each level of preset threshold of the soft bit demodulation method of M-ary quadrature amplitude modulation and obtaining a preset average power value, wherein the value M of M in the M-ary quadrature amplitude modulation is 2^2*PP in the index is a positive integer; and determining the shortest distance a from the position of the rotation symbol to the coordinate axis, wherein the calculation formula of each level of threshold bound _ p is as follows: $\mathrm{bound}\_p=a*2^{P-p}*\sqrt{K},$ wherein, P is 1, 2., P-1;

the bits of the final symbol obtained by calculating the ith symbol according to the threshold are respectively as follows:

$b_i\left(1\right)=\mathrm{real}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

$b_i\left(2\right)=\mathrm{imag}\left({\hat{d}}_{\mathrm{norm}}\left(i\right)\right)$

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b_i(2P-1)＝bound_(P-1)p-|b_i(2P-3)|

b_i(2P)＝bound_(P-1)-|b_i(2P-2)|。

10. the apparatus of claim 9, wherein when the apparatus is applied to 16-ary quadrature amplitude modulation and demodulation in TD-SCDMA, the phase adjustment unit rotates the constellation diagram clockwise by 45 degrees into a rectangular diagram under a rectangular plane coordinate system; adjusting the phase of the received symbol to a corresponding position in a rectangular graph under the rectangular coordinate system after the symbol rotates clockwise by 45 degrees;

the phase adjustment unit of the symbol preprocessing module calculates the rotation symbol according to the following formula

Real part of

Imaginary part

$\mathrm{real}\left({\hat{d}}_{\mathrm{rot}}\right)=\mathrm{real}\left(\hat{d}\right)+\mathrm{imag}\left(\hat{d}\right)$

$\mathrm{imag}\left({\hat{d}}_{\mathrm{rot}}\right)=\mathrm{imag}\left(\hat{d}\right)-\mathrm{real}\left(\hat{d}\right);$

And rotating the symbol

And real part

Imaginary part

And sending the data to an amplitude adjusting unit.

11. The apparatus as claimed in claim 9, wherein the final symbol output by the saturation correction unit further comprises after obtaining each bit: adopting a hard bit demodulation method to directly judge the acquired value, and carrying out the judgment on the b_i(1) To b_i(2P) if the value is not less than 0, the value is judged to be 0, and if the value is less than 0, the value is judged to be 1; or b is the same as_i(1) To b_iThe value of (2P) is 1 when it is 0 or more and 0 when it is less than 0.

12. The apparatus of claim 9, wherein the qam demodulation block demodulates qam having gray code characteristics according to a preset setting, and supports at least 16-ary qam demodulation, 64-ary qam demodulation, or 256-ary qam demodulation.

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