Demodulation device and method for communication system using octic phase-keyed modulation

FIELD: radio engineering.

SUBSTANCE: demodulation device for octic phase-keyed signals receives input signal Rk(Xk, Yk) incorporating k quadrature component Yk and k cophasal component Xk and functions to generate L(sk, 0), L(sk, 1, and L(sk, 2) relaxed-solution values. Computer functions to calculate Zk by subtracting |Yk| level of quadrature signal component Yk from |Xk| level of cophasal signal component Xk. First selector chooses Zk for respective most significant bit of quadrature signal component Yk. Second selector chooses Zk for respective most significant bit of cophasal signal component Xk. Third selector is used to select output signal of second selector or "0" for respective most significant bit in Zk.

EFFECT: facilitated processing required in calculating minimal distance from signal received.

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The technical field

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 is required as input signals for the channel decoder to the demodulator for a digital communication system using a modulation 8-hex phase shift keying (FM).

Prior art

In a digital communication system using a modulation 8-ranks FM, representing a type of multilevel modulations used to increase spectral efficiency, the signal encoded channel encoder is transmitted after the implementation of its modulation. Then the demodulator demodulates the transmitted signal and outputs the demodulated signal to a channel decoder for decoding. Channel decoder performs decoding soft decision error correction. To accomplish this, the demodulator must have the logic to 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.

The algorithms display classified on the procedure simple metric, proposed to the companies Nokia, and procedure of 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 as 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 and the values of the soft decision channel decoder, may to some extent compensate for the deterioration in performance of 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, the computed p is procedure metric double minimum, without the use of 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 using a modulation 8-ranks FM.

Also the present invention is a device and method for calculating values of the soft decision on a simple conditional formula in a digital communication system using a modulation 8-ranks FM.

To achieve these and other results, the proposed demodulation device 8 hex FM for receiving the input signal Rk(Xk,Yk)containing the k-th quadrature component Ykand k-th in-phase component Xkand to generate values Λ (sk,0), Λ (sk,1and Λ (sk,2) soft decisions for the input signal Rk(Xk,Ykby using the soft decision. The device includes a calculator for calculating soft values of Zkby subtracting the level |Yk| quadrature signal component Ykfrom level |Xk| in-phase signal component of Xkthe received signal Rk(Xk,Yk) and output Zkas the first value of the soft decision; a first selector for receiving Zkfrom the solver and the inverted values of Zkfor Zkand the choice of Zkthe if-Z kaccordingly, the most significant bit (MSB) of the quadrature signal component of Yk; a second selector for receiving Zkfrom the solver and Zkand the choice of Zkor-Zkaccordingly, the MSB of the in-phase signal component of Xk; a third selector for receiving the output signal of the second selector and the value “0” and selecting the output signal of the second selector or “0” respectively, the MSB of the function Zk; a first adder for summing the values calculated by multiplying the quadrature signal component of Ykwith the output value of the third selector, and outputting the resultant value as the third value of the soft decision; a fourth selector for receiving the output signal of the second selector and the value “0” and selecting the output signal of the second selector or “0” respectively, the MSB of the function Zk; and a second adder for summing the values calculated by multiplying the in-phase signal component of Xkwith the output of the fourth selector, and outputting the resultant value as the second value of the soft decision.

To achieve these and other findings, the authors proposed a method of demodulating 8-ranks FM for receiving the input signal Rk(Xk,Yk) contains the k-th quadrature component Y kand k-th in-phase component Xkand to generate values Λ (sk,0), Λ (sk,1and Λ (sk,2) soft decisions for the input signal Rk(Xk,Ykby using the soft decision. The method includes the steps of: a) calculating soft values of Zkthe first demodulated symbol by subtracting the level |Yk| quadrature signal component Ykfrom level |Xk| in-phase signal component of Xkthe received signal Rk(Xk,Yka), (b) set the first variable α "0"if the soft value of Zkhas a positive value, setting the first variable α "-1"if the soft value of Zkhas a negative value and the quadrature component Ykhas a positive value, and setting the first variable α 1 if Zkhas a negative value and the quadrature component Ykhas a negative value, (C) determining a soft value of the third demodulated symbol by calculatingusing quadrature component Yksoft values of Zkand the first variable α ; d) set the second variable β "0"if the soft decision Zkhas a negative value, setting the second variable β -1, if Zk has a positive value and the in-phase component Xkhas a negative value, and set the second variable β 1 if Zkhas a positive value and the in-phase component Xkhas a positive value; e) determining a soft value of the second demodulated symbol by calculatingusing the in-phase component Xksoft values of Zkand 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 is a set of signals from the pixels of the display according to 8-ranks FM;

Figure 2 - calculation of the values of the soft decisions in a digital communication system that uses 8-ranks FM in accordance with a possible embodiment of the present invention;

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

4 is a logic diagram of the transmitter of values of mild solutions for use in a digital communication system that uses 8-ranks FM, and

5 is a set of signals from points C is agenia according to 8-ranks FM, for explanation of calculations.

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 for computing multi-dimensional values of the soft decision is required as an input signal of the channel decoder of a two-dimensional received signal, using the procedure of the metric dual of the minimum.

The transmitter divides the output bitstream of the channel encoder to m-bit signal sequence and displays the signal sequence to the corresponding signal point of M(=2m) 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 signal sequence shown on the k-th symbol, a Ikand Qkdenote in-phase (I) and quadrature (Q) signal components of the k-th symbol, respectively. For 8-ranks FM m=3, and the corresponding set of signals presented is a figure 1. As shown in the drawing, a set of signals contains 8 (=23points display, and each point has a phase difference of 45° relative to neighboring pixels of the display.

As shown in figure 1, the symbol is displayed on the in-phase signal component Ikand quadrature signal component Qkand transmitted to the receiver through the transmission medium. After receiving the in-phase signal component and a quadrature signal component of the receiver demodulates received signal components in the demodulator characters. The received signal corresponding to transmitted signal containing the in-phase signal component Ikand quadrature signal component Qkcan be expressed in complex entries according to the following equation (2), taking into account the gain and noise.

Equation (2)

In equation (2) Xkand Ykdenote the in-phase signal component and a quadrature signal component of a two-dimensional received signal displayed on the k-th symbol, respectively. In addition, gkis a complex coefficient representing the coefficients of transmission of the transmitter, transmission medium and receiver. In addition,and- Gaussian noises with zero mean what value is and divergence moreover, these noises are statistically independent from each other.

The demodulator of the characters in the receiver calculates LLP using the received signal Rkaccording to equation (2). The value LLP, corresponding to the i-th bit of sk,i(i=0, 1,... ,m-1) in the output sequence of the channel encoder in the transmitter, can be calculated using equation (3), and the calculated value of the LLP is fed to the channel decoder in the receiver as the value of the soft decision.

Equation(3)

In equation (3) Λ (sk,i) is an LLP or the value of the soft decision corresponding to sk,i, k is a 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, equation (3) is nonlinear, requiring relatively large calculations. It is therefore necessary to approximate 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)

However, equation (4) is also nonlinear. Therefore, equation (4) can be approximated by the procedure of the metric dual of the minimum proposed by Motorola, in the following form:

Equation (5)

In equation (5) K'=(1/σ n 2)K and zk(sk,i=0) and zk(sk,i=1) indicate the actual values of Ik+jQkfor sk,i=0 and sk,i=1, respectively. To compute equation (5), you must define zk(sk,i=0) and zk(sk,i=1) to minimize |Rk-zk(sk,i=0)|2and |Rk-zk(sk z=1)|2for two-dimensional received signal Rk.

Given nk,iindicating the value of the i-th bit of the sequence for the signal point closest to Rkandindicates logical negation operation for nk,iequation (5) can be rewritten in the following form:

Equation (6)

I.e. equation (6) can be calculated by determining whether the value is equal to nk,ithe i-th bit of the sequence for the signal point on the shortest distance from Rkthe value "0" or "1", and determining the minimum value offor the value of the i-th bit of the restore sequence. The value calculated by equation (6), becomes the value of the soft decision values for the i-th bit of the restore sequence. As the value of the soft decision becomes more positive or negative value is Y. the information presented on channel decoder becomes more correct.

Signal point on the shortest distance from Rkis determined by the ranges of values of the inphase signal component and the values of the quadrature signal component of Rk. So the first

term in brackets in equation (6) can be written as follows:

Equation (7)

In equation (7) 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 brackets in equation (6) can be written in the following form:

Equation (8)

In equation (8) Uk,iand Vk,idenote the in-phase signal component and a quadrature signal component of the signal point shown by sequence recoveryfor zkthat minimizesrespectively. Equation (6) can be written as equation (9) using equations (7) and (8) in the following form:

Equation (9)

Λ (sk,i)=K'(2nk,i-1)[{(Xk-Uk)2+(Yk-Vk)2}-{(Xk-Uk,i)2 +(Yk-Vk,i)2}]=

=K'(2nk,i-1)[(Uk+Uk,i-2Xk)(Uk-Uk,i)+(Vk+Vk,i-2Yk)(Vk-Vk,i)]

From equation (9) can be calculated m values of the soft decisions are required as input values of the channel decoder that supports m-level modulation.

Below is described a method of calculating the input values of the soft decision for the channel decoder to the demodulator data transmission system that uses 8-ranks FM, according to equation (9).

First, use table 1 to calculate {nk,2nk,1nk,0}, UkVkof the two signal components Xkand Ykthe modulated 8-ranks of the FM received signal Rk. Table 1 illustrates {nk,2nk,1nk,0}, Ukand Vkfor the case where the received signal Rkoccurs in each of the 8 regions with centers in the signal points shown in figure 1. For convenience, in Table 1 omitted 4 boundary values, i.e. the resulting values for Xk=0, Yk=0, Yk=Xk, Yk=-Xk.

In addition, table 2 illustrates the sequence {mk,2,mk,1,mk,0}that minimizescalculated for i (where i∈ {0,1,2}), in terms of functions {nk,2nk,1nk,0}and also illustreret in-phase and quadrature signal components U k,iand Vk,ithe corresponding zk.

Table 2
i{mk,2,mk,i,mk,0}Uk,iVk,i
2Uk,2Vk,2
1Uk,1Vk,1
0Uk,0Vk,0

Table 3 illustrates the Uk,iand Vk,ithe corresponding {mk,2,mk,1,mk,0}defined in Table 2 for all combinations of {nk,2nk,1nk,0}.

Table 3
{nk,2nk,1nk,0}Uk,2Uk,1Uk,0Vk,2Vk,1Vk,0
{0,0,1}cos(π /8)-sin(π /8)cos(π /8)-sin(π /8)cos(π /8)sin(π /8)
{0,0,0}cos(π /8)-sin(π /8)sin(π /8)-sinπ /8)cos(π /8)cos(π /8)
{0,1,0}-cos(π /8)sin(π /8)-sin(π /8)-sin(π /8)cos(π /8)cos(π /8)
{0,1,1}-cos(π /8)sin(π /8)-cos(π /8)-sin(π /8)cos(π /8)sin(π /8)
{1,1,1}-cos(π /8)sin(π /8)-cos(π /8)sin(π /8)-cos(π /8)-sin(π /8)
{1,1,0}-cos(π /8)sin(π /8)-sin(π /8)sin(π /8)-cos(π /8)-cos(π /8)
{1,0,0}cos(π /8)-sin(π /8)sin(π /8)sin(π /8)-cos(π /8)-cos(π /8)
{1,0,1}cos(π /8)-sin(π /8)cos(π /8)sin(π /8)-cos(π /8)-sin(π /8)

Table 4 illustrates the results obtained by scaling with a decrease in the relationfor values of soft decisions obtained by substituting Uk,iand Vk,ifrom Table 3 into equation (9), i.e. illustri is the duty to regulate the results normalized byI.e. when applied signal Rkit can be defined LLR satisfying the appropriate condition, as the value of the soft decision Table 4. If the channel decoder used in the system, is not a decoder logarithmic maximum a posteriori probability, it must be added to the process of scaling with increasing LLR Table 4 in reverse relation to the scale to decrease.

However, when performing demodulation soft solutions 8-ranks FM using Table 4, the demodulator must first perform an operation condition determination, including the division operation, the two components of the received signal. After that, the demodulator selects the formula corresponding to the result of the operation condition determination among the formulas specified conditions respectively, and supplies the two components of a received signal in the selected formula, thereby calculating the values of the soft decision. To this end, the demodulator requires the operator to perform a division operation and a memory for storing various formulas, corresponding to the condition.

To avoid the division operation and eliminate the need for memory, you need to modify the formula to determine the services the via and formula calculating the value of the soft decision so you can use them the same way even to different conditions. With this purpose, the formula to determine the conditions shown in Table 4, can be expressed as shown in Table 5, using the new function, Zkdefined as |Xk|-|Yk|. In Table 5 of the division operation is eliminated, and the values of the soft decision for 4 boundary values, which for convenience have been omitted in Table 4, here taken into account.

In the implementation of a hardware-based table 5 can be simplified in Table 6, provided that Xk, Ykand Zkcan be expressed by the most significant bit (MSB or sign bit. In Table 6 MSB(x) denotes the most significant bit of this value X.

From Table 6 the values of the soft decision Λ (sk,2), Λ (sk,1and Λ (sk,0for each i is expressed as follows:

Equation (10)

In equation (10) parameter α 0 for MSB(Zk)=0; -1 MSB(Zk)=1 and MSB(Yk)=0; and 1 for the MSB(Zk)=1 and MSB(Yk)=1.

Equation (11)

In equation (11) the parameter β 0 for MSB(Zk)=1; -1 MSB(Zk)=0 and MSB(Xk)=1; and 1 for the MSB(Zk)=0 and MSB(Xk)=0.

Equation (12)

Λ (Sk,0)=Zk

I.e. in a digital communication system that uses 8-ranks FM, it is possible to really calculate 3 values soft solutions, 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 (10)-(12). 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 that uses 8-ranks FM according to a possible variant of implementation of the present invention. According to figure 2 in step S110 demodulator characters computes Zk=|Xk|-|Yk| to determine the formulas that determine the conditions shown in Table 4 as a new feature. The demodulator characters analyzes the MSB for Zkat the step S120 to determine α and β in accordance with the MSB at Zkin equations (1)-(12). The analysis at step S120, if the MSB in the Zk"0", the demodulator of the characters goes to step S130, and otherwise, goes to step S140. At step S130, the demodulator characters analyzes MSB in Xk. The analysis at step S130, if the MSB in Xkequal to "1", then the demodulator characters sets the parameter α to "0" and β "-1" at step S150. If the MSB is X kequal to "0", then the demodulator characters sets the parameter α to "0" and β "1" at step S160.

The analysis at step S120, if the MSB in the Zkequal to "1", the demodulator of the characters on the stage S140 analyzes MSB Yk. The analysis at step S140, if the MSB in Ykequal to "0", then the demodulator characters sets the parameter α -1 and β to "0" at step S170. If the MSB in Ykequal to "1", then the demodulator characters sets the parameter α to "1" and the parameter β to "0" at step S180. After that, at step S190, the demodulator characters calculates the values of the soft decision by substitution parameters α and β defined in the previous steps, and the received signal in equation (10)-(12). This way you demodulation symbols.

Thus, the process of computing the values of the soft decision on the procedure of the metric dual of at least includes a first step of determining the first parameter α and the second parameter β by analyzing the two-dimensional received signal containing the in-phase component and quadrature component, and a second step of calculating the values of the soft decision using a two-dimensional received signal and the first parameter α and the second parameter β defined at the first stage. The obtained values of the soft decision demodulated symbol serves on the canal the first decoder.

Figure 3 shows the transmitter to determine the values of the soft decision demodulated symbol, respectively, a possible variant of implementation of the present invention. According to figure 3 the evaluator to determine the values of the soft decision on the procedure of the metric dual of the minimum in the digital communication system includes an analyzer 10 of the received signal and the block 20 of issuance of the values of the soft decision. The analyzer 10 received signal specifies the first parameter α and the second parameter β by analyzing the two-dimensional received signal containing the in-phase signal component of Xkand quadrature signal component Yk. The block 20 of issuance of the values of the soft decision then calculates the values of the soft decision Λ (sk,2), Λ (sk,1and Λ (Sk,0required for decoding the soft decision using the received signal and the specified parameters α and β .

Logic calculator for calculating soft values of the decision in accordance with equations (10)-(12) is shown in figure 4. In particular, figure 4 shows the transmitter values soft solutions for use in a digital communication system that uses 8-ranks FM. Logic diagram in figure 4 is included in the demodulator of a digital communication system that uses 8-ranks FM, and calculates the values of the soft decision using the EQ is tions (10)-(12). Here a two-dimensional received signal Rk, the in-phase signal component of Xkand quadrature signal component Ykthe variable Zkparameter α and β all are real numbers and a digital value with sign bit. Figure 4 the transmitter 105, the inverter 115, a first block 155 selection MSB, the first selector 110, the third block 165 selection MSB and the third selector 120 to form the structure for determining the first parameter α . In addition, the transmitter 105, the inverter 115, the second block 160 selection MSB, the second selector 135, the third block 165 selection MSB and the fourth selector 140 to form the structure for determining the parameter β .

In accordance with figure 4, the calculator 105 calculates Zk=|Xk|-|Yk| using the in-phase signal component of Xkand quadrature signal component Yktwo-dimensional received signal Rkdisplayed on the k-th symbol. The inverter 115 inverts the sign of Zkby multiplying Zkwith the transmitter 105 to "-1". The first block 155 selection MSB selects the MSB of the received Ykand outputs the selected MSB to the first selector 110 as the first selected signal. The second block 160 selection MSB selects the MSB of the received Xkand outputs the selected MSB to the second selector 135 as a second selected signal. The third block 165 selection MSB selects MSB Z taken from a transmitter 105, and outputs the selected MSB to the third selector 120 as the third selected signal. In addition, Ykmultiplied byin the first multiplier 130 and Xkalso is multiplied byin the second multiplier 150.

The first selector 110 receives Zkfrom the transmitter 105 and a-Zkfrom the inverter 115, and selects one of these input signals respectively to the first selected signal from the first block 155 selection MSB. A third selector 120 then receives the output signal of the first selector 110 and the bit "0" and selects one of the input signals respectively selected third signal from the third block 165 selection MSB. The output signal of the third selector 120 is summed with the output value ofthe first multiplier 130 via the first adder 125, forming a third value of the soft decision Λ (Sk,2) received signal Rkdisplayed on the k-th symbol.

In addition, the second selector 135 accepts Zkfrom the transmitter 105 and a-Zkfrom the inverter 115, and selects one of these input signals, respectively, the second selected signal with the second unit 160 selection MSB. The fourth selector 140 then receives the output signal of the second selector 135 and bit "0" and selects one of these input signals, respectively freemobilegame signal from the third block 165 selection MSB. The output signal of the fourth selector 140 is summed with the output value ofthe second multiplier 150 through the second adder 145, forming the second value of the soft decision Λ (sk,1) received signal Rkdisplayed on the k-th symbol.

The output value of Zktransmitter 105 becomes the first value of the soft decision Λ (sk,0) received signal Rkdisplayed on the k-th symbol.

In accordance with the previous description normal calculator value soft decision using the procedure metric double minimum, sold by the equation (5), requires ten or more operations of squaring and comparison. However, the new evaluator on figure 4, is implemented using equations (10)-(12), contains three adder 3 multiplier and 4 multiplexer, which contributes to considerable reduction in time and complexity of the transmitter. Table 7 illustrates the comparison between equation (5) and equations (10)-(12) in terms of the type and number of operations i∈ {0,1,2}.

tr>
Table 7
Equation (4)Equations (10)-(12)
OperationNumber of operationsOperationNumber of operations
Summation3× 8+3=27Summation3
Squaring2× 8=16Multiplication3
Comparison3× 2× 3=18A mul replacerange4

Below a comparison between the usual way of calculating the value of the Λ (sk,2) using equations (5) and the new method of calculating the value of the Λ (sk,2) using equation (10). Figure 5 shows a set of signals with the point of display, respectively, 8-ranks FM, for explanation of calculations. According to figure 5 two-dimensional received signal Rkcontaining in-phase signal component of Xkand quadrature signal component Ykhas a coordinate value is represented by "x". Here it is assumed that Xk=and-0.6 and Yk=-0,1.

First describe the normal process of calculating the value of the Λ (sk,2) using equation (5).

To determine the shortest distance first, calculate the square of each of distances between the received signal Rkand 4 showing the points in sk,2=1 (i.e. 4 showing the points below the x-axis in figure 5).

The square of the distance from the reflecting point “110”={minus 0.6-cos(9π /8)}2+{-0,1-sin(9π /8)}2=0,185

The square of the distance from the reflecting point “111”={minus 0.6-cos(11π /8)}2+{-0,1-sin(11π /8)}2=0,726

The square of the distance from the reflecting point “101”={minus 0.6-cos(13π /8)}2+{-0,1-sin(13π /8)}2=1,644

The square of the distance from the reflecting point “100”={minus 0.6-cos(15π /8)}2+{-0,1-sin(15π /8)}2=2,402

Therefore, the minimum value (or the shortest distance from the received signal Rk) |Rk-zk(sk,2=1)|2well 0,185.

Then to determine the shortest distance first, calculate the square of each of distances between the received signal Rkand 4 showing the points in sk,2=0 (i.e., 4 showing the points above the x-axis in figure 5).

The square of the distance from the reflecting point "000"={minus 0.6-cos(π /8)}2+{-0,1-sin(π /8)}2=2,555

The square of the distance from the reflecting point "001"={minus 0.6-cos(3π /8)}2+{-0,1-sin(3π /8)}2=2,014

The square of the distance from the reflecting point "011"={minus 0.6-cos(5π /8)}2+{-0,1-sin(5π /8)}2=1,096

The square of the distance from the reflecting point “010”={minus 0.6-cos(7π /8)}2+{-0,1-sin(7π /8)}2=0,338

Therefore, the minimum value of |Rk-zk(sk,2=1)|2well 0,338.

If the results obtained above to substitute in equation (5), the value of the soft decision is received as a

Next described is a new process vicis the possible values Λ (sk,2) using equation (10).

First calculate Zkand α .

Zk=|Xk|-|Yk|=|-0,6|-|-0,1|=0,5

Hence, since Zk0, i.e. the MSB(Zk)=0, α =0.

If the above results are substituted into equation (10), the value of the soft decision would be:

The fact that the result of equation (5) differs from the equation (10), due to the fact that the value of the soft decision, calculated according to equation (9), was normalized byIn the case of turbolader using the kernel maximum logarithmic posteriori probability (currently as L3QS and 1× TREME using the engine maximum logarithmic posteriori probability) normalization of all values LLP (or soft values) using the same factor never affect performance.

If a certain factor, in fact, is multiplied to compute the non-normalized values, then

It should be noted that the calculated normalized value is identical to the result of equation (5).

Thus, in order to reduce the time delay and the complexity caused by the use of procedures for the metric dual of the minimum in equation (5), we shall Aasee the invention provides for the transmission of the tables display (Tables 4-6) through the process in equations (6)-(9) and Tables 1-3. In addition, the present invention provides for the substitution of tables displayed in equations (10)-(12), representing formulas that implement the procedure of the metric dual of the minimum. In addition, the present invention provides a logic circuit calculator for calculating soft values of the 8-ranks FM, implemented according to the equations(10)-(12).

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 8-ranks FM, provides a simple and fast calculations, greatly contributing to the reduction of working time and the complexity of the demodulator, which calculates the values of the soft decision.

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 the 8-hex phase-shift keying (FM) for receiving the input signal Rk(Xk,Yk)containing the k-th quadrature component Ykand k-th in-phase component Xkand degenerative values Λ (sk,0), Λ(sk,1and Λ(sk,2) soft decisions for the input signal Rk(Xk,Ykby using the soft decision containing the analyzer received signal to calculate the functions Zkthe input signal Rk(Xk,Ykaccording to the equation Zk=|Xk|-|Yk| and the definition of the first parameter α and the second parameter β through the input signal and block the issuance of mild solutions to calculate the values of the soft decision for the input signal Rk(Xk,Yk) using the first parameter α and the second parameter β and a received signal Rk(Xk,Ykin accordance with

Λ(sk,0)=Zk

where Λ(sk,iindicates the value of the soft decision corresponding to sk,i(i=0, 1, 2), and sk,iindicates the i-th bit in the sequence of the encoded signal that is displayed on the k-th symbol.

2. Method demodulate 8-hex phase-shift keying (FM) for receiving the input signal Rk(Xk,Yk)containing the k-th quadrature component Ykand k-th in-phase component Xkand to generate values Λ(sk,0), Λ(sk,1and Λ(sk,2) soft decisions for the input signal Rk (Xk,Ykby using the soft decisions, including the steps of calculating soft values of Zkthe input signal Rk(Xk,Ykaccording to the equation Zk=|Xk|-|Yk| and the definition of the first parameter α and the second parameter β through the input signal and calculate a soft decision for the input signal Rk(Xk,Yk) using the first parameter α and the second parameter β and a received signal Rk(Xk,Ykin accordance with

Λ(sk,0)=Zk

where Λ(sk,iindicates the value of the soft decision corresponding to sk,i(i=0, 1, 2), and sk,iindicates the i-th bit in the sequence of the encoded signal that is displayed on the k-th symbol.

3. The device demodulation of the 8-ranks FM for receiving the input signal Rk(Xk,Yk)containing the k-th quadrature component Ykand k-th in-phase component Xkand to generate values Λ(sk,0), Λ(sk,1and Λ(sk,2) soft decisions for the input signal Rk(Xk,Ykby using the soft decision containing a calculator for calculating soft values of Zkby subtracting the level |Yk| uadrature signal component Y kfrom level |Xk| in-phase signal component of Xkthe received signal Rk(Xk,Yk) and output Zkas the first value of the soft decision;

the first selector for receiving Zkfrom the solver and the inverted values of Zkregarding Zkand the choice of Zkor-Zkaccordingly, the most significant bit (MSB) of the quadrature signal component of Yk;

a second selector for receiving Zkfrom the solver and Zkand the choice of Zkor-Zkaccordingly, the MSB of the in-phase signal component of Xk;

a third selector for receiving the output signal of the second selector and the value "0" and selecting the output signal of the second selector or "0" respectively MSB in Zk;

a first adder for summing the values calculated by multiplying the quadrature signal component of Ykwith the output value of the third selector, and outputting the resultant value as the third value of the soft decision;

a fourth selector for receiving the output signal of the second selector and the value "0" and selecting the output signal of the second selector or "0" respectively MSB in Zk; and

a second adder for summing the values calculated by cleverly is placed in-phase signal component of X kwith the output of the fourth selector, and outputting the resultant value as the second value of the soft decision.

4. Method demodulate 8-ranks FM for receiving the input signal Rk(Xk,Yk)containing the k-th quadrature component Ykand k-th in-phase component Xkand to generate values Λ(Λk,0), Λ(Λk,1and Λ(Λk,2) soft decisions for the input signal Rk(Xk,Ykby using the soft decisions, including the steps:

a) calculating soft values of Zkthe first demodulated symbol by subtracting the level |Yk| quadrature signal component Ykfrom level |Xk| in-phase signal component of Xkthe received signal Rk(Xk,Yk),

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

C) determining a soft value of the third dem is dublirovannoe symbol by calculating using quadrature component Yksoft values of Zkand the first variable α;

d) installing a second variable β "0"if the soft decision Zkhas a negative value, setting the second variable β -1, if Zkhas a positive value and the in-phase component Xkhas a negative value, and set the second variable β 1 if Zkhas a positive value and the in-phase component Xkhas a positive value;

e) determining a soft value of the second demodulated symbol by calculatingusing the in-phase component Xksoft values of Zkand the second variable β.



 

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