Device and method for demodulation in communication system, using hexadecimal quadrature amplitude modulation

FIELD: radio engineering.

SUBSTANCE: first calculator calculates soft value Λ of third demodulated symbol of 4 demodulated symbols by subtraction of distance 2a between two demodulated symbols of same axis of indication table from level , quadrature component Yk. Second calculator determines soft value Λ of fourth demodulated symbol by calculating using first variable α. Third calculator calculates soft value Λ of first demodulated signal by subtraction of distance 2a from level of common-mode component Xk. Fourth calculator determines soft value Λ of second demodulated symbol by calculating using second variable β.

EFFECT: higher efficiency.

5 cl, 14 dwg, 12 tbl

 

The present invention relates to a device and method of demodulation in a digital communication system using multi-level modulation, in particular to a device and method for the demodulation, to calculate a soft decision channel decoder to the demodulator for a digital communication system using a 16-hexadecimal quadrature amplitude modulation (QAM).

Prior art

In a digital communication system, when a signal encoded in a channel encoder, is modulated using 16-hexadecimal QAM, which represents a typical multi-level modulation to increase spectral efficiency, the demodulator in the receiver requires the use of the algorithm of the display to generate the values of the soft decision (soft values), the corresponding output bits of the channel encoder, from a two-dimensional signal comprising in-phase signal component and a quadrature signal component to a channel decoder in the receiver was decoding the modulated signal by decoding the soft decision.

The algorithms display classified on the procedure simple metric, proposed by Nokia and the metric dual of the minimum proposed by Motorola. Both algorithms compute the logarithmic likelihood ratio (LLP) for the output bits, and use the calculated LLP is the quality of the input values of the soft decision channel decoder.

The procedure is simple metric that represents the algorithm of the display specified by modifying the formula of the complex calculations LLP, a simple approximate formula is a simple formula to calculate the LLP, but the distortion LLP, caused by the use of the approximate formula, leads to performance deterioration. The procedure is the metric dual of the minimum that represents the algorithm of the display to calculate LLP with a more accurate approximate formula using the calculated LLP as the input values of the soft decision channel decoder, may to some extent compensate for the deterioration of the operating characteristics inherent in the procedure simple metric. However, compared with the procedure simple metric this procedure requires more computation, which leads to a significant increase in the complexity of the hardware.

The invention

Therefore, the present invention is a device and method for facilitating the acquisition of input values of the soft decision channel decoder, calculated by the procedure of the metric dual of the minimum, without using a table display or complex processing required to retrieve the value of the minimum distance to the received signal, a demodulator for a digital communication system that uses 16-R is know CAM.

To achieve these and other findings, the authors proposed a method of demodulating a received signal in a data transmission system that uses a modulation technique for separating the output sequence of the channel encoder 4 bits and the mapping of bits in a particular one of the 16 signal points having a common mode component of Xkand the quadrature component Yk. The method includes the steps of calculating soft values of Zkthe third demodulated symbol by subtracting the distance 2A between two demodulated symbols on the same axis in the grid display of the level |Yk| quadrature signal component Yk; set the first variable α "0"if the soft value of Zkhas a negative value, setting the first variable α ″ 1″ , if Zkhas a positive value and the quadrature component Ykhas a negative value, and set the first variable α 1 if Zkhas a positive value and the quadrature component Ykhas a positive value; determining a soft value of the fourth demodulated symbol by calculating Yk+α *Zkusing quadrature component Yksoft values of Zkand the first variable α ; calculating soft values of Z'k the first demodulated symbol by subtracting the distance 2A between two demodulated symbols on the same axis in the grid display of the level |Xk| in-phase signal component of Xk; set the second variable β "0"if the soft decision Z'khas a negative value, setting the second variable β -1, if Z'khas a positive value and the in-phase component Xkhas a negative value, and set the second variable β on ″ 1 if Z'khas a positive value and the in-phase component Xkhas a positive value; and determining a soft value of the second demodulated symbol by calculating Xk+β *Z’kusing the in-phase component Xksoft Z'kand the second variable β .

Brief description of drawings

The above and other objectives, features and advantages of the present invention are explained in the following detailed description with reference to the drawings, which represent the following:

Figure 1 - diagram of the set of signals for a 16-hexadecimal QAM;

Figure 2 - calculation of the values of the soft decision 4 demodulated symbols at the input of the channel decoder in a digital communication system using a 16-hexadecimal QAM in accordance with zmeinym of the embodiment of the present invention;

Figure 3 - functional block diagram of the transmitter to perform the procedure to determine the values of the soft decision for the demodulated symbols in accordance with a possible embodiment of the present invention;

Figure 4 - demodulator characters to determine the values of the soft decision channel decoder in a digital communication system using a 16-hexadecimal QAM, in accordance with a possible embodiment of the present invention.

A detailed description of the preferred option of carrying out the invention

The preferred implementation of the present invention is described below with reference to illustrative drawings. In the following description, well-known functions or constructions are not described in detail so as not to clutter the invention with unnecessary detail.

The present invention provides a method of obtaining the input soft values of the channel decoder using the procedures of the metric dual of the minimum without the use of a table display or complex calculations in a demodulator for a data transmission system using 16-hexadecimal QAM.

The following describes the algorithm for generating multidimensional soft values from a two-dimensional received signal. The output sequence of a binary channel encoder is divided into m bits, and appears to correspond to the s signal point of M (=2 m) signal points according to the encoding rule code gray. This can be represented as follows:

Equation (1)

In equation (1) Sk,i(i=0,1,... ,m-1) denotes the i-th bit in the output sequence of a binary channel encoder, shown on the k-th symbol, a Ikand Qkdenote in-phase and quadrature signal components of the k-th symbol, respectively. For 16-hexadecimal QAM m=4 and the corresponding set of signals presented in figure 1. As shown in the drawing, a set of signals contains 16 signal points, each quadrant contains 4 signal points.

Each signal point is expressed by 4 characters. For example, in figure 1 the first quadrant is divided into 4 areas; the upper-right pane is displayed on the character stream "0000", the lower right region is displayed on a character stream "0100", left top area appears in the character stream "0001" and the lower left region is displayed on a character stream "0101".

The integrated output signal of the demodulator of characters in the receiver, containing the in-phase signal component Ikand quadrature signal component Qk, is defined as follows:

Equation (2)

In equation (2) Xkand Ykdenote the phase signaline the component and the quadrature signal component of the output signal of the demodulator characters, respectively. In addition, gkis a complex coefficient representing the coefficients of transmission of the transmitter, transmission medium and receiver. In addition, ηIkand ηQk- Gaussian noises with zero mean value and divergence σ2nand these noises are statistically independent from each other.

The value of the LLP, the corresponding sequence sk,i(i=0,1,...,m-1), can be calculated using equation (3), and the calculated value of the LLP can be used as the value of soft decisions supplied to the channel decoder.

Equation (3)

In equation (3) Λ (sk,i) is the value of the soft decision, K - constant, Pr{A|B} is the conditional probability defined as the probability that event a will occur when the condition that caused the condition C. However, because equation (3) is nonlinear and requires a relatively large computing needs an algorithm for approximation of equation (3) for the actual implementation. In the case of channels with Gaussian noise, with gk=1 in equation (2), equation (3) can be written as follows:

Equation (4)

In equation (4) K'=(1/σn2) And zk(s ,i=0) and Zk(sk,i=1) denote the actual values of Ik+jQkfor sk,i=0 and sk,i=1, respectively. To calculate equation (4), you must define zk(sk,i=0) and zk(sk,i=1) by minimizing |Rk-zk(sk,i=0)|2and |Rk-zk(sk,i=1)|2for two-dimensional received signal R2.

Equation (4), approximated by means of the procedure of the metric dual of the minimum can be rewritten in the following form:

Equation (5)

In equation (5) nk,iindicates the value of the i-th bit of the sequence for the signal point closest to Rkandindicates the negation of nk,i. The nearest signal point is determined by the ranges of values of the inphase signal component and the values of the quadrature signal component of Rk. The first term in brackets in equation (5) can be written as follows:

Equation (6)

In equation (6) Ukand Vkdenote the in-phase signal component and a quadrature signal component of the signal point shown by nk={nk,m-1...,nk,i,... ,nk,1nk,0} respectively.

In addition, the second term in the brackets in equation (5) can be written in the following form:

Equation (7)

In equation (7) Uk,iand Vk,idenote the in-phase signal component and a quadrature signal component of the signal point shown by the sequence {mk,m-1,... ,mk,i,... mk,1,mk,0} for zkminimize |Rk-Zk(sk,i=)|2respectively. Equation (5) is rewritten as equation (8) using equations (6) and (7).

Equation (8)

Below is described a method of calculating the input values of the soft decision for the channel decoder to the demodulator communication system using a 16-hexadecimal QAM. First, use table 1 and table 2 to calculate {nk,3nk,2nk,1nk,0}, UkVkof the two signal components Xkand Ykmodulated 16-hexadecimal QAM received signal Rk. Table 1 illustrates {nk,3nk,2and Vkfor the case where the quadrature signal component of Ykthe received signal Rkoccurs in each of the 4 areas parallel to the horizontal axis in figure 1. For convenience, in Table 1 omitted 3 boundary values, i.e. the resulting values for Yk=-2a, Yk=0 and Yk=2a. Table 2 illustrare the {n k,1nk,0and Ukfor the case where the in-phase signal component of Xkthe received signal Rkoccurs in each of the 4 areas parallel to the vertical axis in figure 1. For convenience, in Table 2 omitted 3 boundary values, i.e. the resulting values for Xk=-2a, Xk=0 and Xk=2a.

Table 1
The condition for Yk(nk,3nk,2)Vk
Yk>2a(0,0)3A
0<Yk<2a(0,1)and
-2a<Yk<0(1,1)-and
Yk<-2a(1,0)-3A

Table 2
The condition for Xk(nk,1nk,0)Uk
Xk>2a(0,0)3A
0<Xk<2a(0,1)and
-2a<Xk<0(1,1)-and
Xk<-2a(1,0)-3A

Table 3 illustrates the sequence {mk,3, mk,2, mk,1, mk,0}, min is Misirlou |R k-zk(Sk,i=)|2calculated for i (where i∈ {0,1,2,3}, in terms of functions {nk,3nk,2nk,1nk,0}and also illustrates in-phase and quadrature signal components Uk,iAnd Vk,ithe corresponding zk.

Table 3
i{mk,3, mk,2, mk,1, mk,0}Vk,iUk,i
3{, 1, nk,1nk,0}Vk,3Uk
2{nk,3,nk,1nk,0}Vk,2Uk
1{nk,3nk,2,nk,0}VkUk,i
0{nk,3nk,2nk,1}VkUk,0

Table 4 and table 5 show the Vk,iand Uk,ithe corresponding (mk,3, mk,2) and (mk,1,mk,0calculated in Table 3 for all combinations (nk,3nk,2) and (nk,1nk,0).

Table 4
(nk,3nk,2)Vk,3Vk,2
(0,0)-anda
(0,1)-and3A
(1,1)and-3A
(1,0)and-and

Table 5
(nk,1nk,0)Uk,iUk,0
(0,0)-aa
(0,1)-and3A
(1,1)and-3A
(1,0)and-and

Table 6 and table 7 illustrate the results obtained by scaling with the decrease in the ratio K ha for soft values of the solutions obtained by substituting Vk,iand Uk,ifrom Table 4 and Table 5 in equation (8). I.e. when applied signal Rkit can be defined LLR satisfying the corresponding condition as the value of the soft decision according to Table 6 and Table 7. If the channel decoder used in the system, is not a logarithmic decoder maximum aposterior the second probability, it should be added to the process of scaling with increasing LLR Table 6 and Table 7 in reverse relation to the scale to decrease.

Table 6
The condition for YkΛ(sk,3)Λ(sk,2)
Yk>2a2Yk-2aYk-2a
0<Yk<2aYkYk-2a
-2a<Yk<0Yk-Yk-2a
Yk<-2a2Yk+2a-Yk-2a

Table 7
The condition for XkΛ(sk,1)Λ(sk,0)
Xk>2a2Xk-2aXk-2a
0<Xk<2aXkXk-2a
-2a<Xk<0Xk-Xk-2a
Xk<-2a2Xk+2a-Xk-2a

However, when the input soft values of the channel decoder using Tables 6 and 7 display demodulate is, unfortunately, I have to first perform the operation of determining the conditions for the received signal and requires memory for storing the output of the content according to the corresponding condition. Such shortcomings can be overcome by calculating the values of the soft decision channel decoder using a formula expressing a simple operation condition determination instead of table display.

With this purpose, the formula to determine the conditions shown in Tables 6 and 7, can be expressed as shown in Tables 8 and 9. In Table 8 Zk=|Yk|-2a and in Table 9 Z'k=|Xk|-2a. In Tables 8 and 9 taken into account even soft value 3 limit values, which were omitted in Tables 6 and 7 for convenience.

Table 8
The condition for YkThe condition for ZkΛ (sk,3)Λ (sk,2)
Yk>0Zk>0Yk+(Yk-2a)Yk-2a
Zk<0YkYk-2a
Yk<0Zk>0Yk-(-Yk-2a)-Yk-2a
Zk<0Yk-Y k-2a

Table 9
The condition for XkThe condition for Z'kΛ (sk,1)Λ (sk,0)
XkoZ'k0Xk+(Xk-2a)Xk-2a
Z'k<0XkXk-2a
Xk<0Z'k0Xk-(-Xk-2a)-Xk-2a
Z'k<0Xk-Xk-2a

In the implementation of a hardware-based Tables 8 and 9 can be simplified in the form of Tables 10 and 11, provided that Xk, Yk, Zkand Z'kcan be expressed through significant bits. In Tables 10 and 11 MSB(x) denotes the most significant bit (MSB) of the given values of X.

Table 10
MSB(Yk)MSB(Zk)Λ (sk,3)Λ (sk,2)
00Yk+ZkZk
1YkZk
1aboutYk-ZkZk
1YkZk

Table 11
MSB(Xk)MSB (Z'k)Λ (sk,i)Λ (sk,o)
00Xk+Z'kZ'k
1XkZ'k
10Xk-Z'kZ'k
1XkZ'k

From Table 10 the values of the soft decision Λ (sk,3and Λ (sk,2for i=3 and i=2 are expressed as follows:

Equation (9)

From Table 11, the values of the soft decision Λ (sk,1and Λ (sk,0for i=1 and 1=0 can be expressed as follows:

Equation (10)

I.e. in a digital communication system, and the use of 16-hexadecimal QAM, it is indeed possible to calculate the values of the soft decisions, which are output signals of the demodulator for a single received signal or the input signal of the channel decoder, using the procedures of the metric dual of the minimum in equation (4)by simple computational formulas according to equations (9) and (10). This process is illustrated in figure 2.

Figure 2 shows the procedure to calculate the values of the soft decision in a digital communication system using a 16-hexadecimal QAM according to a possible variant of implementation of the present invention. According to figure 2 the process of determining the soft decision through the procedures of the metric dual of the minimum can be subdivided into the first stage of the definition of α by analyzing the quadrature signal component and the values "a" and the definition of β by analyzing the in-phase signal component and the values "a" and the second stage of issuing soft values defined by the values α and β obtained at the first stage. The operation, described below, may be performed, for example, the demodulator of the characters in the receiver.

According to figure 2 on the phase demodulator 201 characters computes Zk=|Yk|-2a using a two-dimensional received signal Rkconsisting of in-phase component Xkand quadrature component Ykand the distance 2A between the two demodulated symbols on the same axis in the grid display. Here Zk,YkXkand "a" are real numbers. The demodulator of the characters on the stage 203 determines whether the resulting value calculated by the above formulas, a positive value. For example, Zk, YkXkand "a" is expressed by a numerical value, including the sign bit. Therefore, at step 203 demodulator symbol determines whether the MSB (or sign bit) of the result value is equal to "0". If the MSB is equal to "0", the demodulator of the characters goes to step 205. Otherwise, the demodulator of the characters goes to step 209, where he sets the parameter α to "0". At step 205 demodulator symbol determines whether the quadrature component Yka positive value, i.e. determines whether the MSB in Yka value of "0". If Ykhas a positive value, the demodulator of the characters on stage 208 sets the variable α to "1". Otherwise, the demodulator characters sets the variable α "-1" at step 207. Then at step 210 the demodulator symbol defines a fourth demodulated symbol sk,3of the demodulated symbols corresponding to the accepted signal Rkusing Yk+α *Zkand determines the third demodulated symbol sk,2using Zk, thereby defining the input soft value for Kahn is a high decoder.

So far we described the procedure for determining the soft values for the third and fourth demodulated symbols using quadrature component. Then is described the procedure for determining the soft values for the second and the first demodulated symbols using in-phase component.

At step 211, the demodulator characters computes Z'k=|Xk|-2A using a two-dimensional received signal Rkconsisting of in-phase component Xkand quadrature component Ykand the distance 2 between two demodulated symbols on the same axis in the grid display. The demodulator of the characters on the stage 213 determines whether the resulting value calculated by the above formulas, a positive value, i.e. determines whether the MSB (or sign bit) of the result value is equal to "0". If the resulting value is positive, the demodulator of the characters goes to step 215. Otherwise, the demodulator of the characters goes to step 219, where he sets the parameter β to "0". At step 215 demodulator symbol determines whether the in-phase component Xka positive value, i.e. determines whether the MSB in Xka value of "0". If Xkhas a positive value, the demodulator of the characters on stage 218 set is assigned the variable β to "1". Otherwise, the demodulator characters sets the variable β "1" at step 217. Then at step 220 the demodulator symbol defines a second demodulated symbol sk,1of the demodulated symbols corresponding to the accepted signal Rkusing Xk+β *Zkand defines a first demodulated symbol sko using Zk, thereby defining the input soft value for the channel decoder. The procedure for determining the third and fourth demodulated symbol and the procedure of determination of the second and first demodulated symbols can be executed either sequentially or simultaneously. The received soft values of demodulated symbols are served in the channel decoder.

Figure 3 shows the functional block diagram for the procedure of determining the values of the soft decision demodulated symbols, respectively, a possible variant of implementation of the present invention. According to figure 3, the analyzer 301 quadrature signal component calculates the variable α using quadrature signal component Ykthe received signal Rkand the distance 2A between two demodulated symbols on the same axis table display according to the predetermined rule. As stated above, the variable ; computed based on the sign of Zk(=|Yk|-2A) and the sign of the quadrature signal component of Yk. The first block 302 issuance soft values solves the equation (9) using the variable α analyzer 301 quadrature signal component of the quadrature signal component of Ykand distance 2A and generates soft values of the third and fourth demodulated symbols.

The analyzer 303 in-phase signal component calculates the variable β using in-phase signal component of Xkthe received signal Rkand the distance 2A between two demodulated symbols on the same axis table display according to the predetermined rule. As stated above, the variable β calculated on the basis of the sign of the Z'k(=|Xk|-2a) and the sign of the inphase signal component Xk. The second block 304 issuing soft values solves the equation (10) using the variable β analyzer 303 in-phase signal component, the in-phase signal component of Xkand distance 2a and generates soft values of the second and first demodulated symbols.

Figure 4 shows the demodulator symbol to calculate a soft decision channel decoder in the data transmission system using 16-hexadecimal QAM, according to a possible variant of the implementation of this is th invention, moreover, the demodulator symbols implemented by the hardware based on equations (9) and equation (10). Here a two-dimensional received signal Rk, the in-phase signal component of Xkand quadrature signal component Ykthe variable Zkthe variable Z'kparameter α and β all are real numbers with a numeric value, including the sign bit.

In accordance with figure 4, the first calculator 401 calculates Zk=|Yk|-2a using a quadrature signal component of Ykthe received signal Rkand the distance 2a between two demodulated symbols on the same axis table display and displays the value of Zk. The multiplier 402 multiplies Zkfrom the first transmitter 401 to -1 to invert the sign of Zk. The first block 403 selection MSB selects the MSB of the quadrature signal component of Ykand submits it to the first selector 405, and the second block 404 selection MSB selects MSB Zkfrom the first transmitter 401 and supplies it to the second selector 406. The first selector 405 accepts Zkfrom the first transmitter 401 and "-Zk" from the first multiplier 402 and selects one of two inputs respectively to the select signal from the first block 403 selection MSB. The second selector 406 receives the output signal from the first selector 405 and "0" and selects the od is about from two inputs respectively to the select signal from the second unit 404 selection MSB. The first adder 407 adds the output signal of the second selector 406 and a quadrature signal component of Ykand gives a soft value of the fourth demodulated symbol. In addition, the value of Zkcalculated by the first calculator 401, issued as a soft value of the third demodulated symbol.

The second calculator 411 calculates Z'k=|Xk|-2a using the in-phase signal component of Xkthe received signal Rkand the distance 2A between two demodulated symbols on the same axis table display and outputs the value Z'k. The multiplier 412 multiplies Z'kwith the second transmitter 411 -1 to invert the sign of the Z'k. The third block 413 selection MSB selects the MSB of the in-phase signal component of Xkand supplies it to the third selector 415, and the fourth block 414 selection MSB selects MSB Z'kwith the second transmitter 411 and supplies it to the fourth selector 416. A third selector 415 accepts Z'kwith the second transmitter 411 and ' - Z'k" with the second multiplier 412 and selects one of two inputs respectively to the select signal from the third block 413 selection MSB. The fourth selector 416 receives the output signal of the third selector 415 and "0" and selects one of two inputs respectively to the select signal from the fourth block 414 selection MSB. The second sums the tor 417 adds the output signal of the fourth selector 416 and the in-phase signal component of X kand gives a soft value of the second demodulated symbol. In addition, the value of Z'kcalculated by the second calculator 411, issued as a soft value of the third demodulated symbol.

Below is a comparison between a known procedure to obtain soft values and a new procedure to obtain soft values in the sense of achievable efficiency.

In the case of a calculator, the values of the soft decision using the procedure metric double minimum, sold by the equation (5), such a conventional method of determining a soft decision requires dozens of operations of squaring and comparison, while new demodulator symbols in figure 4 contains 4 adders, 2 multipliers and 4 multiplexer, which contributes to considerable reduction in time and complexity of the transmitter. Table 12 illustrates the comparison between equation (4) and equations (9)-(10) in terms of the type and number of operations i∈ {0,1,2,3}.

Table 12
Equation (4)Equations (9) and (10)
OperationNumber of operationsOperationNumber of operations
Summation3× 16+4=52Summation4
Squaring2× 16=32Multiplication2
Comparison7× 2× 4=56Multiplexing4

In the end, the present invention displays a Table 6-11 from equations (6)-(8) the process according to Tables 1-5, in order to reduce the delay time and the complexity that can occur when equation (4) is known procedures metric double minimum, or equation (5)obtained by the simplified metric double minimum, are implemented using a 16-hexadecimal quadrature amplitude modulation (QAM). In addition, the present invention provides the equations (9) and (10)representing the new formulas that are used to implement procedures for the metric dual of a minimum of 16 hexadecimal QAM. In addition, the present invention provides a device implemented by the hardware based on equations (9) and equation (10).

As described above, when obtaining the values of the soft decision required as input to the channel decoder in the procedure metric double minimum, new demodulator for a digital communication system using a modulation by 16 hexadecimal QAM, provides a simple and fast computations for obtaining the same result as in the case of using the known formulas. The transmitter Myagkov the values implemented in hardware, greatly reduces the working time and the complexity of the demodulator.

Although the invention is shown and described with reference to its preferred variant implementation, it should be borne in mind that specialists in this field of technology can be made various changes in form and details without deviating from the essence and scope of the invention as presented in the claims.

1. The device demodulation of 16 hexadecimal quadrature amplitude modulation (QAM) for receiving the input signal Rk(Xk,Yk)containing the k-th quadrature component Ykand k-th in-phase component Xkand to generate the soft values Λ(Sk,0), Λ(Sk,1), Λ(Sk,2and Λ(Sk,3for input signal Rk(Xk,Ykby using the soft decision containing the first block definition soft values for determining the soft values Λ(Sk,0and Λ(Sk,1the first and second demodulated symbols from 4 demodulated symbols according to the following equations:

where Λ(Sk,0) denotes the soft value of the first demodulated symbol, Λ(Sk,1) train ACHAT soft value of the second demodulated symbol, MSB means most significant bit or sign bit, |Xk| denotes the absolute value of the inphase component of Xkand 2A denotes the distance between two demodulated symbols on the same axis table display;

and the second block for determining the soft values for determining the soft values Λ(Sk,2and Λ(Sk,3) the third and fourth demodulated symbols from 4 demodulated symbols according to the following equations:

where Λ(Sk,2) denotes the soft value of the third demodulated symbol, Λ(Sk,3) denotes the soft value of the fourth demodulated symbol, |Yk| denotes the absolute value of the quadrature component Ykand 2A denotes the distance between two demodulated symbols on the same axis in the grid display.

2. The device according to claim 1, characterized in that the first unit determining the soft values includes a first calculator to calculate Z'k=|Xk|-2A using the in-phase component Xkand the distance 2A between two demodulated symbols on the same axis table display and issuing Z'kas the soft value of the first demo is Ulyanova symbol; the first selector to obtain Z'kfrom the first transmitter and the inverted signal Z'kand select one of these two input signals respectively significant bit in-phase component Xk; a second selector for receiving the output signal of the first selector and the signal "0" and select one of these two input signals respectively significant bit Z'kand the first adder for summing the output signal of the second selector and the in-phase component Xkand issuance of the soft value of the second demodulated symbol.

3. The device according to claim 1, characterized in that the first unit determining the soft values includes a second calculator for calculating Zk=|Yk|-2A using quadrature component Ykand the distance 2A between two demodulated symbols on the same axis table display and issuance of Zkas the soft values of the third demodulated symbol; a third selector for receiving Zkfrom the second transmitter and the inverted signal Zkand select one of these two input signals respectively sign bit of the quadrature component Yk; a fourth selector for receiving the output signal of the third selector and the signal "0" and select one of these two input signals respectively significant bit of Zkand the Torah adder for summing the output signal of the fourth selector and the quadrature component Y kand issuing soft values of the fourth demodulated symbol.

4. The demodulation device 16 hex quadrature amplitude modulation (QAM) for receiving the input signal Rk(Xk,Yk)containing the k-th quadrature component Ykand k-th in-phase component Xkand to generate the soft values Λ(Sk,0), Λ(Sk,1), Λ(Sk,2and Λ(Sk,3for input signal Rk(Xk,Ykby using the soft decision containing a first calculator for determining a soft value Λ(Sk,2) of the third demodulated symbol from 4 demodulated symbols by subtracting the distance 2A between two demodulated symbols on the same axis in the grid display of the absolute value |Yk| quadrature component Yk; a second calculator for determining a soft value Λ(Sk,2fourth demodulated symbol by calculating Yk+α·Zkusing the first variable αdefined soft value of the third demodulated symbol and the sign bit of the quadrature component Ykwhere Zk- soft value of the third demodulated symbol; a third calculator for determining a soft value Λ(Sk,0the first demodulated symbol by the subtraction distance 2A from the absolute values |X k| in-phase component Xk; a fourth calculator for determining a soft value Λ(Sk,1the second demodulated symbol by calculating Xk+α·Zkusing the second variable βdefined soft value of the first demodulated symbol and the sign bit in-phase component Xkwhere Z'k- soft value of the first demodulated symbol.

5. The device according to claim 4, characterized in that the second computer sets the first variable α "0"if the soft value of Zkthe third demodulated symbol has a negative value, sets the first variable α -1, if Zkhas a positive value and the quadrature component Ykhas a negative value, and sets the first variable α 1 if Zkhas a positive value and the quadrature component Ykhas a positive value.

6. The device of claim 4, wherein the fourth computer sets a second variable β "0"if the soft value Z'kthe first demodulated symbol has a negative value, sets a second variable β -1, if Z'khas a positive value and the in-phase component Xkhas a negative value, and ustanavli is no second variable β on 1 if Z'khas a positive value and the in-phase component Xkhas a positive value.

7. The way demodulation of 16 hexadecimal quadrature amplitude modulation (QAM) for receiving the input signal Rk(Xk,Yk)containing the k-th quadrature component Ykand k-th in-phase component Xkand to generate the soft values Λ(Sk,0), Λ(Sk,1), Λ(Sk,2and Λ(Sk,3for input signal Rk(Xk,Ykby using the soft decisions, including the steps

calculating soft values Λ(Sk,0and Λ(Sk,1the first and second demodulated symbols from 4 demodulated symbols according to the following equations:

where Λ(Sk,0) denotes the soft value of the first demodulated symbol, Λ(Sk,1) denotes the soft value of the second demodulated symbol MSB means most significant bit or sign bit, |Xk| denotes the absolute value of the inphase component of Xk, 2a denotes the distance between two demodulated symbols on the same axis table display; and

calculating soft values Λ(Sk and Λ(Sk,3) the third and fourth demodulated symbols from 4 demodulated symbols according to the following equations:

where Λ(Sk,2)denotes the soft value of the third demodulated symbol, Λ(Sk,3) denotes the soft value of the fourth demodulated symbol, |Yk| denotes the absolute value of the quadrature component Yk, 2a denotes the distance between two demodulated symbols on the same axis in the grid display.

8. The method according to claim 1, characterized in that the first step of calculating soft values includes the steps of calculating Z'k=|Xk|-2a using the in-phase component Xkand the distance 2A between two demodulated symbols on the same axis table display and outputting the calculated Z'kas the soft value of the first demodulated symbol;

selecting as the first selected signal soft Z'kthe first demodulated symbol or the inverted signal of the soft values of Z'kthe first demodulated symbol, respectively significant bit in-phase component Xk;

selecting as the second selected signal is and the first selected signal or signal "0", respectively significant bit soft values Z' kthe first demodulated symbol and

summation of the second selected signal and the common mode component of Xkand issuance of the soft value of the second demodulated symbol.

9. The method according to claim 7, characterized in that the second step of calculating soft values includes the steps

Zk=|Yk|-2a using quadrature component Ykand the distance 2A between two demodulated symbols on the same axis table display and issuance of Zkas the soft values of the third demodulated symbol;

selecting as the third selected signal soft values of Zkthe third demodulated symbol or the inverted signal of the soft values of Zkthe first demodulated symbol respectively sign bit of the quadrature component Yk;

selection as the fourth selected signal of the third selected signal or signal "0", respectively significant bit of Zkand

summation of the fourth selected signal and the quadrature component Ykand issuing soft values of the fourth demodulated symbol.

10. The way demodulation signal 16 hex quadrature amplitude modulation (QAM) for receiving the input signal Rk(Xk,Yk)containing the k-th quadrature stood the Commissioner, Y kand k-th in-phase component Xkand to generate the soft values Λ(Sk,0), Λ(Sk,1), Λ(Sk,2and Λ(Sk,3for input signal Rk(Xk,Ykby using the soft decisions, including the steps

(a) calculating soft values Λ(Sk,2) of the third demodulated symbol from 4 demodulated symbols by subtracting the distance 2A between two demodulated symbols on the same axis in the grid display of the absolute value |Yk| quadrature component Yk,

(b) determining a soft value Λ(Sk,3fourth demodulated symbol by calculating Yk+α·Zkusing the first variable αdefined soft value of the third demodulated symbol and the sign bit of the quadrature component Ykwhere Zk- soft value of the third demodulated symbol;

(c) calculating soft values of A(Sk,0the first demodulated symbol by subtracting a distance 2A from the absolute values |Xk| in-phase component Xkand

(d) determining a soft value Λ(Sk,1the second demodulated symbol by calculating Xk+β·Z'kusing the second variable βdefined me is Kim the value of the first demodulated symbol and the sign bit in-phase component X kwhere Z'k- soft value of the first demodulated symbol.

11. The method according to claim 10, wherein step (b) involves the installation of the first variable α "0"if the soft value of Zkthe third demodulated symbol has a negative value, setting the first variable α -1, if Zkhas a positive value and the quadrature component Ykhas a negative value, and set the first variable α 1 if Zkhas a positive value and the quadrature component Ykhas a positive value.

12. The method according to claim 10, wherein step (d) involves the installation of the second variable β "0"if the soft value Z'kthe first demodulated symbol has a negative value, setting the second variable β -1, if Z'khas a positive value and the in-phase component Xkhas a negative value, and

install the second variable β 1 if Z'khas a positive value and the in-phase component Xkhas a positive value.

13. The method of demodulating a received signal in a data transmission system that uses a modulation technique for separating the output sequence of the channel encoder 4 bits and the mapping of bits in a particular one of the 16 SIG is real points, having in-phase component Xkand the quadrature component Ykincluding milestones

calculating soft values of Zkthe third demodulated symbol by subtracting the distance 2A between two demodulated symbols on the same axis in the grid display of the level |Yk| quadrature signal component Yk;

set the first variable α "0"if the soft value of Zkhas a negative value, setting the first variable α -1, if Zkhas a positive value and the quadrature component Ykhas a negative value, and set the first variable α 1 if Zkhas a positive value and the quadrature component Ykhas a positive value;

determining a soft value of the fourth demodulated symbol by calculating Yk+α·Zkusing quadrature component Yksoft values of Zkand the first variable α;

calculating soft values of Z'kthe first demodulated symbol by subtracting the distance 2A between two demodulated symbols on the same axis in the grid display of the absolute values |Xk| in-phase signal component of Xk;

installation vtoro the variable β "0"if the soft decision Z'khas a negative value, setting the second variable β -1, if Z'khas a positive value and the in-phase component Xkhas a negative value, and set the second variable β 1 if Z'khas a positive value and the in-phase component Xkhas a positive value; and

determining a soft value of the second demodulated symbol by calculating Xk+β·Z'kusing the in-phase component Xksoft Z'kand the second variable β.



 

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