WO2012163011A1

WO2012163011A1 - Decoding method and device of mimo system

Info

Publication number: WO2012163011A1
Application number: PCT/CN2011/080940
Authority: WO
Inventors: 李希
Original assignee: 中兴通讯股份有限公司
Priority date: 2011-06-03
Filing date: 2011-10-18
Publication date: 2012-12-06
Also published as: CN102811117B; CN102811117A

Abstract

The present invention relates to a decoding method and device of an MIMO system. The method comprises: calculating, according to a modulation symbol r received by a system, a projection s̃₂of a modulation symbol _s1 transmitted by a current transmitting terminal on a modulation symbol _s2transmitted by another transmitting terminal; performing quantitative estimation on a real part s̃_2,I and an imaginary part s̃_2,Q of the s̃₂, to obtain estimated values _s2,I and _s2,Q of the real part s̃_2,I and the imaginary part s̃_2,Qof the s̃₂; performing constellation mapping on the _s2,I and _s2,Q to obtain a position of the _s2 in a constellation graph; calculating, according to the position of the _s2, an error D of an estimated value and an actual value of the _s1; updating, according to the D, minimum errors min_dist_0[k] and min_dist_1[k] between the estimated value and the actual value of the _s1; and calculating, according to the min_dist_0[k] and min_dist_1[k], a log likelihood ratio of each bit of the _s1 to obtain a decoding result. The decoding complexity of the present invention is low.

Description

Decoding method and device for MIMO system

The present invention relates to the field of communications technologies, and in particular, to a decoding method and apparatus for a MIMO (Multiple Input Multiple-Output) system. Background technique

Multi-antenna transmission technology plays an important role in improving the capacity and reliability of wireless communication systems. Distributed access methods are also the hotspot of high-speed packet transmission research. The transmission signal is simultaneously transmitted and received by multiple antennas, and the wireless channel between the transmitting end and the receiving end is changed into a MIMO system by a conventional SISO (Single-Input Single-Out-put) system, and the communication system is It has space resources other than traditional time, frequency, and code channel resources. Theoretical studies have shown that the MIMO channel is a superposition of multiple SISO channels, and its capacity is proportional to min(A^, N), where N _R is the number of transmitting and receiving antennas, respectively. This shows that when the number of transmitting and receiving antennas is increased, the channel capacity can be effectively increased. Therefore, MIMO systems provide a huge potential for improving the information throughput of wireless networks, expanding coverage areas, and improving transmission quality. MIMO technology can generate independent parallel channels in space to simultaneously transmit multiple data streams, thus effectively increasing the transmission rate of the system, that is, increasing the capacity and spectrum utilization of the communication system without increasing the system bandwidth. . The MIMO-OFDM (Orthogonal Frequency Division Multiplexing) system combines the advantages of OFDM technology and MIMO technology and has great potential in improving the transmission rate and reliability of wireless links.

Detection and decoding techniques in MIMO-OFDM systems are also a hot topic of research. Due to the simultaneous transmission of multiple antennas, there is co-channel interference. The advantages and disadvantages of the receiver's detection technology and the complexity directly affect the performance and application prospects of the system. The receiver with the maximum likelihood detection algorithm (ML/MAP) can achieve optimal performance, but the complexity is too high. The current hardware processing can The force can not meet the computing requirements, and can only be applied when the number of antennas and the modulation order are small. Linear receiving methods (such as zero-forcing detection algorithm ZF, minimum mean square error detection algorithm MMSE) have low complexity but poor performance, and there are interference cancellation algorithms and spherical decoding algorithms between ML and linear reception. The interference cancellation algorithm needs to subtract the first detected data portion from the received signal, so there is a phenomenon of error propagation, and the performance is affected by the interference cancellation order. The sphere decoding algorithm is a simplification of the maximum likelihood algorithm. By dynamically changing the center and radius of the search to reduce the number of searches, the performance of the ML is close to the performance of the ML at high SNR, but the complexity is low, but at low SNR. The search time is still relatively long and the complexity is still high. How to reduce the complexity of the optimal detection algorithm and avoid the limitations of the traditional detection algorithm application is meaningful to the implementation of the system. Summary of the invention

In view of the above, an object of the present invention is to provide a decoding method and apparatus for a MIMO system to optimize the problem that the complexity of the existing decoding method is too high.

The present invention provides a decoding method for a MIMO system, including:

The modulation symbols r received by the system, the terminal calculates the current transmission modulation symbols transmitted modulation symbols ^ projected on another _¾ of the transmission the transmitting terminal;

Quantitative estimation of the real and imaginary parts s ~ ₂ , _Q above, and the estimated value of the real part s ~ _2J and the imaginary part ₂ , _e , _3⁄4β ;

Performing constellation mapping on the above _3⁄4ί , _3⁄42 to obtain the position of the modulation symbol _3⁄4 in the constellation diagram; calculating the error between the estimated value and the actual value of the modulation symbol _S1 according to the position of the modulation symbol _3⁄4 obtained in the constellation diagram D;

Updating the minimum errors min_dist_0[k] and min_dist_l [k] between the estimated value and the actual value of the above-mentioned modulation symbol ^ according to the above error D, where k represents the k-th bit of the modulation symbol; according to the minimum error min_dist_0[k] And min_dist_l[k], calculating the log likelihood ratio of each bit of the modulation symbol ^ transmitted by the current transmitting terminal, and obtaining a decoding result. Preferably, the calculating the projection of the modulation symbol transmitted by the current transmitting terminal on the modulation symbol transmitted by the other transmitting terminal is:

Calculating the mode II h ₂ II ^{2 of the} channel response of the other transmitting terminal;

Calculating a conjugate transpose h ₂ ^{H of the} channel response of the other transmitting terminal;

Calculating the product of /^ above the modulation symbol r received by the above system;

Calculating the above-mentioned product of the channel response / 3⁄4 of the current transmitting terminal;

Calculating the current current according to the modularity II h ₂ II ^{2 of the} channel response of the other transmitting terminal, the product of the above-mentioned modulation symbol r received by the above system, and the product of the above-mentioned / / channel response of the current transmitting terminal / 3⁄4 The projection of the modulation symbol transmitted by the transmitting terminal on the modulation symbol _3⁄4 transmitted by the other transmitting terminal.

Preferably, the projection of the modulation symbol transmitted by the modulation symbol transmitted on the current transmitting terminal on the other transmitting terminal is calculated by the following formula:

Where /3⁄4 denotes the channel response of the above other transmitting terminal, indicating a conjugate transpose of /3⁄4, and 11/3⁄4 11 ² is the modulus of /3⁄4.

Preferably, the above calculation of the modulation symbol transmitted by the current transmitting terminal ^ on the modulation symbol transmitted by the other transmitting terminal is:

Calculating a conjugate transpose of a channel response of the other transmitting terminal;

Calculating a product of the above /^ and the channel response /3⁄4 of the current transmitting terminal;

Calculating the modulation of the modulation symbol _S1 transmitted by the current transmitting terminal at another transmitting terminal according to the product of the above-mentioned modulation symbol r received by the above system and the product of the above-mentioned /^ and the channel response of the current transmitting terminal. The projection on symbol _3⁄4 .

Preferably, the modulation symbol transmitted on the current transmitting terminal is calculated by the following formula ^ Projection of modulation symbols transmitted on a transmitting terminal:

Where /3⁄4 represents the channel response of the other transmitting terminal, indicating a conjugate transpose of /3⁄4. Preferably, the above-described real part ί _2ί and imaginary part ί _{2 β} are estimated by the following formula:

3)

3)

Where, the real part of the representation, the imaginary part of the representation, L" means rounding down.

Preferably, the real part _2ί and the imaginary part _{2 e of} the pair are quantitatively estimated, and an estimated value of the real part ₂ _ί and the imaginary part _{2 e} is obtained, where _e is:

Calculating the mode II II ^{2 of the} channel response of the other transmitting terminal;

Calculate the intermediate estimate of the real part above based on the following formula:

s _{2 I} = [(s _2I

"

Calculate the intermediate estimate s _{e of the} above imaginary part ₂ , _β according to the following formula:

s _{2 Q}

Determine if the above is less than ll/^ ll ² , and if so, then =0; otherwise,

Determine if the above is less than 0, and if so, then =1; otherwise,

Determine whether the above is less than 2ll / 3⁄4 ll ² , and if so, then = 2; otherwise, s ₂ ,, = 3;

Judging whether the above s _e is less than ll / ^ ll ² , and if so, then s ₂ , _e =0; otherwise,

Determine whether the above ^ is less than 0, and if so, then s ₂ , _e = l; otherwise,

It is judged whether the above s _e is less than 2||/3⁄4 11 ² , and if so, then = 2; otherwise, = 3.

Preferably, the error D between the estimated value of the above modulation symbol ^ and the actual value is calculated by the following formula:

D =11 rs^ -s ₂ h ₂ II ²

Where ^ represents the modulation symbol transmitted by the current transmitting terminal, and /3⁄4 indicates the current transmission A channel response of the terminal, indicating a modulation symbol transmitted by the another transmitting terminal, indicating a channel response of the another transmitting terminal.

Preferably, the method further comprises: initializing the values of the elements in the minimum errors min_dist_0[k] and min_dist_l[k] to positive infinity when the system is initialized.

Preferably, the minimum error min_dist_0[k] and min_dist_l [k] between the estimated value and the actual value of the modulation symbol ^ are updated according to the error D described above:

Judging the value of the kth bit ^ of the above modulation symbol ^,

If _s f =0, it is judged whether the above error D is smaller than min_dist_0[k], and if so, let min_dist_0[k]=D; otherwise, min_dist_0[k] is not updated;

If s = l, it is judged whether the above error D is smaller than min_dist_l[k], and if so, let min_dist_l [k] = D; otherwise, min_dist_l [k] is not updated.

Preferably, the log likelihood ratio of each bit of the modulation symbol ^ transmitted by the current transmitting terminal is calculated by the following formula:

LLR = min_dist_l [k]- min_dist_0[k]

Where LLR^ represents the log likelihood ratio of the kth bit of the modulation symbol transmitted by the current transmitting terminal.

The present invention also provides a decoding apparatus for a MIMO system, comprising: a projection module, an estimation module, a mapping module, an error calculation module, a minimum error update module, and a log likelihood ratio calculation module, wherein the projection module is configured to receive according to a system modulation symbols r, the transmitting terminal calculates the current modulation symbol transmitted on a projection ^ modulation symbols transmitted to another transmitting terminal of _¾;

Above estimation module, for the above-mentioned real and imaginary portions _2, _e is quantized estimates, obtained in the above _{2> ί} real part and an imaginary part _2, _e estimate _¾ί, s _2>e;

Above mapping module configured above _{_¾ί, ¾e} constellation mapping, modulation symbols _¾ obtain the position in the constellation diagram;

The above error calculation module is configured for the modulation symbol _3⁄4 obtained according to the above estimation in the constellation diagram Position, calculating an error D between the estimated value of the modulation symbol ^ and the actual value;

The minimum error update module is configured to update a minimum error min_dist_0[k] and min_dist_l [k] between the estimated value and the actual value of the modulation symbol ^ according to the error D, wherein k represents a k-th bit of the modulation symbol ;

The log likelihood ratio calculation module is configured to calculate a log likelihood ratio of each bit of the modulation symbol ^ transmitted by the current transmitting terminal according to the minimum errors min_dist_0[k] and min_dist_l [k], and obtain a decoding result. .

Preferably, the apparatus further includes an initialization module, configured to initialize the values of the elements in the minimum errors min_dist_0[k] and min_dist_l[k] to positive infinity when the MIMO system is initialized.

Preferably, the projector module further configured to mold the channel response calculation the other terminal of the transmitting / ¾ square 11 / ¾11 ^2, another transmitting terminal calculates the channel response / ¾ of calculating the conjugate transpose of h ₂ ^H a product of the modulation symbol r received by the above system and calculating a product of the above-mentioned channel response with the current transmitting terminal;

The above estimation module is further configured to calculate a modulus \\h ₂ \\ ^{2 of the} channel response of the another transmitting terminal; calculate an intermediate estimated value of the real part _2ί , and calculate an intermediate estimated value of the imaginary part _{2 β} _And determining whether the above is less than -211 h ₂ II ² , and when the above is less than -211 h ₂ II ² , the above estimated value 3⁄4 is equal to 0, and when the above is greater than or equal to -211 II ² , determining whether the above s is If the value is less than 0, and the above-mentioned less than 0, the above estimated value is equal to 1, and when the above is greater than or equal to 0, it is judged whether the above is less than 211 h ₂ II ² , and when the above is less than 211 h ₂ II ² , the above estimated value is obtained. Equivalent to 2, above the above 211 / ^ 11 †, so that the above estimated value is equal to 3; determine whether the above ₂ is less than -2 ι / 3⁄4ιι ² , and above the above -2 ιι / 3⁄4ιι ² , the estimated value of the above s _e s ₂ , _e is equal to 0, when the above s _{e is} greater than or equal to -2||/3⁄4|| ² , it is judged whether the above s _e is less than 0, and when the above s _{e is} less than 0, the estimated value s _{2 of the} above s _e is obtained , _e is equal to 1, When the above s _{e is} greater than or equal to 0, it is judged whether the above s _e is less than 2|| /3⁄4 || ² , and the above s _{e is} smaller than

2ιι / ¾ ιι ^2, so the above estimate s _e s _2, _e is equal to 2, the above s _e greater than or equal 2ιι / ¾ ιι ^2, so that said estimated value ^ is equal to 3;

The minimum error update module is further configured to determine a value of the kth bit ^ of the modulation symbol ^, and when the above =0, determine whether the error D is smaller than min_dist_0[k], where the error D is smaller than min_dist_0[k] When the value of min_dist_0[k] is equal to the above error D, when the error D is greater than or equal to min_dist_0[k], min_dist_0[k] is not updated; or in the above ^=1, it is determined whether the error D is 'j, at min_dist_l [k], when the above error D is smaller than min_dist_l [k], let the value of min_dist_l[k] be equal to the above error D, and when the above error D is greater than or equal to min_dist_l [k], min_dist_l [k] is not updated.

The invention optimizes the problem that the complexity of the traditional MAP algorithm is too high, and the decoded result calculated by the invention is equivalent to soft demodulation soft information, and can be directly used for decoding without demodulation, for multi-antenna, high-order and low The order modulation has a good decoding effect. DRAWINGS

The drawings are intended to provide a further understanding of the invention, and are intended to be a part of the invention. In the drawing:

1 is a flow chart of a preferred embodiment of a decoding method of a MIMO system of the present invention;

2 is a schematic diagram of a 16QAM constellation;

3 is a schematic diagram of a constellation of estimated modulation symbols;

4 is a schematic block diagram of a preferred embodiment of a decoding apparatus for a MIMO system of the present invention. detailed description

The basic idea of the present invention is: calculating, according to the modulation symbol r received by the system, a projection of the modulation symbol transmitted by the current transmitting terminal on the modulation symbol _3⁄4 transmitted by the other transmitting terminal; _{2 ί} real part and an imaginary part _{2 β-described} quantizing estimation to obtain an estimated value of _{2 ί} _¾ of the real part and the imaginary part of the _{2 β,} _'e; the _¾,' _e constellation mapping, modulation symbols obtained _¾ of the position in the constellation diagram; D based on the estimated error between the obtained position of the modulation symbols in the constellation, the modulation symbols ^ calculating estimated and actual values; D according to the error, update the a minimum error min_dist_0[k] and min_dist_l[k] between the estimated value of the modulation symbol ^ and the actual value, where k represents the kth bit of the modulation symbol; according to the minimum error min_dist_0[k] and min_dist_l[k] And calculating a log likelihood ratio of each bit of the modulation symbol ^ transmitted by the current transmitting terminal to obtain a decoding result.

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments in order to make the present invention. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

As shown in FIG. 1 , it is a flowchart of a preferred embodiment of the decoding method of the MIMO system of the present invention. In this embodiment, 16QAM is taken as an example, and a constellation diagram thereof is shown in FIG. 2 , where 0. 0 ₃ 0 ₂ represents 4 bits corresponding to each modulation symbol in the 16QAM constellation, c is a normalization factor, and 16 modulation symbols are respectively marked as (^, < ₂ , ···, C ₁₆ , because In the invention, it does not matter how the modulation symbol mark and the modulation symbol correspond, so the specific positions of the 16 modulation symbols are not shown in the figure. Each modulation symbol has 4 bits. Assuming that the MIMO system has an NRX root receiving antenna, the system model as follows:

Where r ₁ , r ₁ ... r _i ^ represent the modulation symbols received by the antenna of the MIMO system; ^ represents the modulation symbol transmitted by one transmitting terminal of the MIMO system, indicating the channel of the transmitting terminal at the receiving antenna NRX Response; represents a modulation symbol transmitted by another transmitting terminal of the MIMO system, h _N , ₂ represents a channel response of the transmitting terminal at the receiving antenna NRX; The noise of the antenna of the MIMO system is received.

make:

n = [n _l , n ₂ , - - - n _NR∑ ] ^T

Then the above system model becomes:

r = sfy + 5 ₂ /3⁄4 + n

Where r denotes a modulation symbol received by the MIMO system; ^ denotes a modulation symbol transmitted by a transmitting terminal of the MIMO system,

Representing the channel response of the transmitting terminal; representing the modulation symbol transmitted by another transmitting terminal of the MIMO system, s ₂ e 3⁄4^ ₂ , . . . , ^ ₆ }, /3⁄4 indicating the channel response of the transmitting terminal; η indicating noise.

Based on the above model, the embodiment includes the following steps:

Step S001: Initialize the minimum errors min_dist_0[k] and min_dist_l[k] between the estimated value and the actual value of the modulation symbol ^ transmitted by the current transmitting terminal, and set the value of each element to positive infinity, that is:

Min_dist_0[k]=+∞

Min_dist_l[k]= + ^oc

Where k represents the kth bit of the modulation symbol, and in 16QAM, k = 0, 1, 2, 3. Step S002: The modulation symbol r received by the system calculates the current transmission modulation symbols transmitted by the terminal on a projection of ^ another transmit modulation symbols transmitted _¾ of the terminal;

In the first embodiment, the step specifically includes:

Step S10: Calculate the module II h ₂ II ^{2 of the} channel response of the other transmitting terminal and save it; Step S11: Calculate the conjugate transpose/^ of the channel response of the other transmitting terminal and save it; Step S12: Calculating the product A of the above / ^ and the modulation symbol r received by the above system and saving, that is, A= h ₂ ^H r

Step S13: Calculate the product B of the channel response/3⁄4 of the current transmitting terminal and save it;

B= h ₂ ^H

Step S14: According to the module response II/3⁄4 II ^{2 of the} channel response of the other transmitting terminal, the above and the above A and B, calculate the modulation symbol transmitted by the current transmitting terminal and transmit at another transmitting terminal by the following formula Projection on the modulation symbol _3⁄4 :

3⁄4 = h ₂ ^H (r - sA) / II /z ₂ II ² = (A - _Sl B) /||/i ₂

In the first embodiment, for different modulation symbols, a complex multiplication, a complex subtraction, and a division of the real multiple are performed at a time to obtain a corresponding projection.

In the first embodiment, a division operation is required, and the overhead is relatively large, and the embodiment can be further optimized.

In the second embodiment, the step specifically includes:

Step S10: Calculate the conjugate transpose /^ of the channel response of the other transmitting terminal and save it; Step Sir: calculate the product A of the above /^ and the modulation symbol r received by the above system and save it;

Step S12,: calculating a product B of the above-mentioned / / channel response / 3⁄4 of the current transmitting terminal and saving;

Step S13,: calculating, according to the above / ^ and A, B, the projection of the modulation symbol transmitted by the current transmitting terminal on the modulation symbol _3⁄4 transmitted by the other transmitting terminal by the following formula:

2 = ιξ (r - _Sl )VlO = (A - _Sl B)y/

Where /3⁄4 represents the channel response of the other transmitting terminal, indicating a conjugate transpose of /3⁄4. Compared with the first embodiment, the second embodiment only needs to perform complex multiplication, one complex subtraction and one complex multiplication with real numbers for different modulation symbols to obtain corresponding projections.

Step S003: performing quantitative estimation on the real part _2ί and the imaginary part _2e described above, and obtaining an estimated value of the real part and the imaginary part _{2 e} , _e ;

In this step,

_2/ = real s ₂ );

s _2Q = imag(s ₂ );

If the above-described embodiment calculates a current transmit modulation symbols transmitted terminal ^ projected onto modulation symbols in another transmission _¾ of the transmitting terminal in step S002 employed in this step by the steps of the above-described real part and an imaginary part s ~ _2J ₂ , _e to estimate:

Step S20: Calculate the intermediate estimate of the real part above according to the following formula:

s _2I = [(s _2I

"

Step S21: Calculate the intermediate estimated value s _e of the imaginary part _2β described above according to the following formula:

s _2Q = [(s _2Q

"

Step S22: According to the above s,

Calculating an estimated value of the real part and the imaginary _2ί portions of the _¾ί s ~ _2, _Q by the following equation estimates _¾e

"), 3)

= min ( max ( 0, s _2I ), 3 )

0.5"), 3)

=min ( max ( 0, s _2Q ), 3 )

If the projection of the modulation symbol transmitted by the current transmitting terminal on the modulation symbol _3⁄4 transmitted by the other transmitting terminal is calculated in the second embodiment, the step is performed by the following steps. The actual part _{2> ί} and imaginary part ₂ , _β are estimated:

Step S20:: Calculate the module II II ^{2 of the} channel response of the other transmitting terminal and save it; Step S21: Calculate the intermediate estimated value of the real part according to the following formula:

s _2I = [(s _2I

Step S22,: calculating the intermediate estimated value s _e of the imaginary part _S ~ _l , _Q according to the following formula: s _2Q = [(s _2Q

Step S23,: determining whether the above is less than ^ ΙΙ / ^ ΙΙ ² , and if so, executing step S24, otherwise, performing step S25;

Step S24,: s ₂ =0, step S30 is performed;

Step S25,: determining whether the above is less than 0, and if yes, executing step S26, otherwise, performing step S27;

Step S26,: s ₂ = l, performing step S30;

Step S27,: determining whether the above ^ is less than 2ll II ² , and if so, executing step S28, otherwise, performing step S29;

Step S28,: s ₂ = 2, performing step S30;

Step S29,: s ₂ = 3, performing step S30;

Step S30,: determining whether the above s _e is less than ^ ΙΙ / ^ ΙΙ ² , and if so, executing step S31, otherwise, performing step S32;

Step S31,: s _2Q =0, the evaluation ends;

Step S32,: respectively determining whether the above s _e is less than 0, and if so, executing step S33, otherwise, performing step S34;

Step S33,: s ₂ ^=l, the evaluation ends;

Step S34,: determining whether the above s _e is less than 211 / i ² , and if so, executing step S35, otherwise, performing step S36; Step S35,: s ₂ ^=2, the evaluation ends;

Step S36,: s ₂ ^= , the valuation ends.

Step S004: the above _ί, _e constellation mapping, modulation symbols _¾ obtain the position in the constellation diagram;

As shown in FIG. 3, it is a constellation diagram of the estimated modulation symbol, and the I path is the horizontal axis.

_{The 3⁄4} map represents the real part of the modulation symbol, the Q path is the vertical axis, and the _e- map represents the imaginary part of the modulation symbol s. For example, when s _2i =l, s _2e =3, the estimated modulation symbol is mapped to point 0 in the upper left corner of the second quadrant in the figure.

Step S005: calculating an error D between the estimated value and the actual value of the modulation symbol ^ according to the position of the modulation symbol _{3⁄4 obtained} in the constellation diagram;

In this step, the error between the estimated value of the above modulation symbol ^ and the actual value is calculated by the following formula D:

D =11 rs^ -s ₂ h ₂ II ²

Wherein, ^ represents the modulation symbol transmitted by the current transmitting terminal, /3⁄4 represents the channel response of the current transmitting terminal, and represents the modulation symbol transmitted by the other transmitting terminal, indicating the channel response of the other transmitting terminal.

Step S006: Update the minimum errors min_dist_0[k] and min_dist_l[k] between the estimated value and the actual value of the modulation symbol ^ according to the distance D, where k represents the kth bit of the modulation symbol;

This step is specifically as follows:

Step S0061: determining the value of the kth bit ^ of the modulation symbol ^, if =0, executing step S0062; if =1, executing step S0065;

Step S0062: determining whether the error D is less than min_dist_0[k], and if so, executing step S0063, otherwise, performing step S0064; Step S0063: Let min_dist_0[k]=D;

Step S0064: Do not update min_dist_0[k];

Step S0065: determining whether the error D is smaller than min_dist_l [k], if yes, executing step S0066, otherwise, performing step S0067;

Step S0066: Let min_dist_l[k]=D;

Step S0067: Min_dist_l [k] is not updated.

Step S007: Calculate a log likelihood ratio of each bit of the modulation symbol ^ transmitted by the current transmitting terminal according to the minimum errors min_dist_0[k] and min_dist_l [k] to obtain a decoding result.

In this step, the log likelihood ratio of each bit of the modulation symbol ^ transmitted by the current transmitting terminal is calculated by the following formula:

LLR = min_dist_l [k]- min_dist_0[k]

Where LLI^k represents the log likelihood ratio of the kth bit of the modulation symbol transmitted by the current transmitting terminal.

As shown in FIG. 4, it is a schematic block diagram of a preferred embodiment of a decoding apparatus of a MIMO system according to the present invention. In this implementation, the decoding apparatus includes a projection module 02, an estimation module 03, a mapping module 04, an error calculation module 05, and a minimum error update. a module 06 and a log likelihood ratio calculation module 07, wherein the initialization module 01 is configured to initialize the values of the elements in the minimum errors min_dist_0[k] and min_dist_l[k] to positive infinity when the MIMO system is initialized;

a projection module 02, configured to calculate and calculate a channel II II ^{2 of a} channel response of the another transmitting terminal according to the modulation symbol r received by the system, and calculate a channel response of the another transmitting terminal/conjugate conjugate transposition / ^ and save, calculate the above / ^ product of the modulation symbol r received by the above system and save and calculate the above-mentioned product of the channel response / 3⁄4 of the current transmitting terminal and save, and according to the channel response of the other transmitting terminal /3⁄4 of the square II /3⁄4 II ² , the product of the above-mentioned modulation symbol r received by the above system and the above / ^ and the channel of the current transmitting terminal Calculating the projection of the modulation symbol transmitted by the current transmitting terminal on the modulation symbol transmitted by the other transmitting terminal, or the product of the modulation symbol r received by the above system and the above-mentioned /^ and the current current channel response transmitting terminal / ¾ product, calculates the current transmit modulation symbols transmitted terminal ^ projection estimation module modulation symbols transmitted in the transmitting terminal further _¾ 03, for the above-mentioned real and imaginary portions _2, _e estimate quantized to obtain the above-mentioned real and imaginary portions _2, _e estimates _{_¾, ¾β;} in particular: the other transmitting terminal for calculating a channel response of h ₂ norm II h _² II ₂ and stored; calculated The intermediate estimated value ^ of the real part s ~ _2J above, calculates the intermediate estimated value s _e of the imaginary part _2β ; and determines whether the above ^ is less than -2\\h ₂ \\ and is less than -2ll/3⁄4ll ² Let the above estimated value of ί _2ί be equal to 0. When the above is greater than or equal to -211 /3⁄4 II ² , judge whether the above is less than 0, and when the above is less than 0, let the above estimated value 3⁄4 be equal to 1, in the above s, greater than When it is equal to 0, judge the above s, is it In 2ll / ¾ll ^2, in the above less than ² 2ll / ¾ll, so that the above-described ί estimate _2ί equal to 2, in the not less than 211 ¾ ² II, so the above estimate ¾ equal to 3; determining whether the s _e is less than Ll / ^ ll ² , and when the above s _{e is} less than -2ll / 3⁄4ll ² , let the estimated value _{e of the} above s _e be equal to 0, when the above s _{e is} greater than or equal to -2||/3⁄411 ² , determine whether the above s _e is less than 0, and when said s _e less than 0, so the above estimate s _e s _2, _e is equal to 1, in the s _e greater than or equal to 0, determining whether the

Is it less than 2ll/3⁄4ll ² , when the above is less than 2ll/3⁄4ll ² , let the above estimated value _{3⁄42 be} equal to 2, when the above s _{e is} greater than or equal to 2ιι/3⁄4ιι ² , let the estimated value of the above s _e _{3e4e be} equal to 3;

The mapping module 04 is configured to perform constellation mapping on the above _i and _e to obtain a position of the modulation symbol _3⁄4 in the constellation diagram;

The error calculation module 05 is configured to calculate an error D between the estimated value of the modulation symbol and the actual value according to the position of the modulation symbol _3⁄4 in the constellation diagram obtained by the above estimation; The minimum error update module 06 is configured to update the minimum errors min_dist_0[k] and min_dist_l[k] between the estimated value and the actual value of the modulation symbol ^, where k represents the kth bit of the modulation symbol; specifically: determining The value of the kth bit ^ of the modulation symbol ^, and when the above =0, determines whether the error D is smaller than min_dist_0[k], and when the error D is smaller than min_dist_0[k], the value of min_dist_0[k] is equal to The error D, when the error D is greater than or equal to min_dist_0[k], does not update min_dist_0[k]; or in the above ^=1, determines whether the error D is 'j, at min_dist_l [k], where the error D is less than min_dist_l When [k], let the value of min_dist_l [k] be equal to the above error D, and when the above error D is greater than or equal to min_dist_l [k], min_dist_l [k] is not updated.

The log likelihood ratio calculation module 07 is configured to calculate a log likelihood ratio of each bit of the modulation symbol ^ transmitted by the current transmitting terminal according to the minimum errors min_dist_0[k] and min_dist_l [k], and obtain a decoding result. .

The above description shows and describes a preferred embodiment of the present invention, but as described above, it should be understood that the present invention is not limited to the form disclosed herein, and should not be construed as being Other combinations, modifications, and environments are possible and can be modified by the teachings of the above teachings or related art within the scope of the inventive concept described herein. All changes and modifications made by those skilled in the art are intended to be within the scope of the appended claims.

Claims

Claim

A decoding method for a multiple input multiple output MIMO system, the method comprising:

Quantifying and estimating the real part s ~ _2J and the imaginary part _S ~ _l , _Q , and obtaining the estimated values _3⁄4 , _3⁄4β of the real part s ~ _2J and the imaginary part ₂ , _e ;

Performing constellation mapping on the _3⁄4i , , _e to obtain a position of the modulation symbol 3⁄4 in the constellation diagram; calculating an estimated value and an actual value of the modulation symbol _S1 according to the position of the modulation symbol obtained in the constellation diagram Error D;

Updating a minimum error min_dist_0[k] and min_dist_l [k] between the estimated value and the actual value of the modulation symbol ^ according to the error D, wherein k represents a k-th bit of the modulation symbol; according to the minimum error Min_dist_0[k] and min_dist_l[k] calculate a log likelihood ratio of each bit of the modulation symbol ^ transmitted by the current transmitting terminal to obtain a decoding result.

2. The method of claim 1, wherein said transmitting terminal calculates current modulation symbols transmitted modulation symbols ^ projected on another transmitting terminal is transmitted _¾:

Calculating a product of the /^ and the modulation symbol r received by the system;

Calculating a product of the channel response of the current transmitting terminal;

According to the module II II ² of the channel response of the other transmitting terminal, the product of the modulation symbol r received by the system and the product of the channel response/3⁄4 of the current transmitting terminal, Calculating a modulation symbol transmitted by the current transmitting terminal and transmitting a modulation at another transmitting terminal The projection on the symbol _3⁄4 .

3. Method according to claim 1 or 2, characterized in that the modulation symbol transmitted on the current transmitting terminal is calculated by the following formula: the projection of the modulation symbol transmitted on the other transmitting terminal

s ₂ =h ₂ ^H (rs _l h _l )l\\h ₂ \\ ²

Where /3⁄4 denotes the channel response of the other transmitting terminal, indicating a conjugate transpose of /3⁄4, and 11/3⁄411 ² is a modular square of /3⁄4.

4. The method of claim 1, wherein said transmitting terminal calculates current modulation symbols transmitted modulation symbols ^ projected on another transmitting terminal is transmitted _¾:

Calculating a modulation symbol transmitted by the current transmitting terminal according to a product of the modulation symbol r received by the system and the channel response of the current transmitting terminal

Projection of the _Sl on the modulation symbol _3⁄4 transmitted by the other transmitting terminal.

The method according to claim 1 or 4, wherein the modulation symbol transmitted on the current transmitting terminal is calculated by the following formula: a projection of a modulation symbol transmitted on another transmitting terminal

Where /3⁄4 denotes the channel response of the other transmitting terminal, indicating a conjugate transpose of /3⁄4.

6. Method according to claim 3, characterized in that said real part _{2 > ί} and imaginary part _2e are estimated by the following formula:

"), 3)

"), 3) Where, the real part of the representation, the imaginary part of the representation, L" means rounding down.

7. The method according to claim 5, wherein the real part _2ί and the imaginary part ₂ , _{e of} the pair are quantitatively estimated, and the real part and the imaginary part ₂ are obtained, and the estimated values of the _e are _3⁄4 , _3⁄4e are:

The intermediate estimate s of the real part is calculated according to the following formula:

s _2I = [(s _2I

"

Calculate the intermediate estimate s _e of the imaginary part ₂ , _β according to the following formula:

s _{2 Q} = [(s _2Q

"

Determining whether the said is less than ll/^ ll ² , and if so, then =0; otherwise,

Determining whether the said is less than 0, and if so, then =1; otherwise,

It determines whether less than 2ll / ¾ ll ^2, if yes, 2 =; otherwise, _¾, = 3; Analyzing the s _e is less than ll / ^ ll ^2, if yes, s _2, _e = 0; otherwise,

Determining whether the ^ is less than 0, and if so, then s ₂ , _e = l; otherwise,

It is determined whether the s _e is less than 211/3⁄4 11 ² , and if so, then = 2; otherwise, = 3.

8. The method according to claim 1, wherein the error D between the estimated value and the actual value of the modulation symbol is calculated by the following formula:

D =11 rs^ -s ₂ h ₂ II ²

Wherein, a modulation symbol transmitted by the current transmitting terminal is indicated, and /3⁄4 represents a channel response of the current transmitting terminal, and represents a modulation symbol transmitted by the another transmitting terminal, indicating a channel response of the another transmitting terminal.

9. The method according to claim 1, wherein the method further comprises: initializing the values of the elements in the minimum errors min_dist_0[k] and min_dist_l[k] to positive infinity when the system is initialized.

The method according to claim 1 or 9, wherein the minimum error min_dist_0[k] and min_dist_l [k] between the estimated value and the actual value of the modulation symbol ^ is updated according to the error D ] is:

Determining the value of the kth bit ^ of the modulation symbol ^,

If s =0, it is judged whether the error D is smaller than min_dist_0[k], and if so, let min_dist_0[k]=D; otherwise, min_dist_0[k] is not updated;

If _s f = l , it is judged whether the error D is smaller than min_dist_l[k], and if so, let min_dist_l [k] = D; otherwise, min_dist_l [k] is not updated.

The method according to claim 1, wherein the log likelihood ratio of each bit of the modulation symbol ^ transmitted by the current transmitting terminal is calculated by the following formula:

LLR = min_dist_l [k]- min_dist_0[k]

12. A decoding device for a MIMO system, the device comprising: a projection module, an estimation module, a mapping module, an error calculation module, a minimum error update module, and a log likelihood ratio calculation module;

The projection module, the system according to the received modulation symbol r calculated current transmit modulation symbols transmitted by the terminal on a projection of ^ another transmit modulation symbols transmitted _¾ of the terminal;

Said estimation module for the real and imaginary portions _2, _e is quantized estimates, to obtain the real and imaginary parts of _{2 β} estimation value _{_¾ί, ¾β;}

The mapping module, for the _{_¾ί, ¾2} constellation mapping, modulation symbols _¾ obtain the position in the constellation diagram;

The error calculation module is configured to calculate an error D between the estimated value and the actual value of the modulation symbol according to the estimated position of the modulation symbol ₂₂₆ in the constellation;

The minimum error update module is configured to update the modulation symbol according to the error D a minimum error between the estimated value and the actual value min_dist_0[k] and min_dist_l [k], where k represents the kth bit of the modulation symbol;

The log likelihood ratio calculation module is configured to calculate a log likelihood ratio of each bit of the modulation symbol ^ transmitted by the current transmitting terminal according to the minimum errors min_dist_0[k] and min_dist_l[k], The result of the decoding.

13. The apparatus according to claim 12, wherein the apparatus further comprises an initialization module, configured to: when the MIMO system is initialized, the elements of the minimum errors min_dist_0[k] and min_dist_l[k] The value is initialized to positive infinity.

14. Apparatus according to claim 12 or claim 13 wherein:

The projection module is further for calculating a channel of the other transmitting terminal in response to the norm of 11 / ¾11 ^2, further calculating the channel response transmitting terminal / ¾ conjugate transpose with the system calculates the a product of the received modulation symbol r and a product of the channel response/3⁄4 of the current transmitting terminal;

The estimation module is further configured to transmit to another terminal of said mold calculating channel response square 11 / ¾11 ^2; calculating the real part of the intermediate _2ί estimation value s ,, intermediate _2β calculating the estimated imaginary part a value s _e ; and determining whether the said value is less than -2 II /3⁄4 11 ² , and when the said less than -2 II /3⁄4 11 ² , the estimated value 3⁄4 is equal to 0, in the greater than or equal to -211 II ² , determining whether the s is less than 0, and when the less than 0, let the estimated value be equal to 1, and when the greater than or equal to 0, determining whether the said is less than 2||/3⁄411 ² Said that, when less than 211 /3⁄4 II ² , let the estimated value be equal to 2, in the said greater than or equal to 211 / ^ 11 †, let the estimated value be equal to 3; determine whether the s _e is less than ^ ΙΙ / ^ ΙΙ ^2, and the s _e is less than -2 || / ² when ¾11, so that the estimated value _e s s _2, _e is equal to 0, the s _e greater than or equal -2ll / ² when ¾ll, Analyzing the s _e is smaller than 0, and when the s _e is smaller than 0, so that the estimate s _e s _2, _e is equal to 1, in the s _e greater than or equal to 0, it is determined whether the s _e Less than 211 / i ² , where the s _{e is} less than 2ιι / ¾ιι ^2, so that the estimate s _e s _2e is equal to 2 or greater in the s _e 2ιι / ¾ιι ^2, so that the estimation value ^ s _2, _e is equal to 3;

The minimum error update module is further configured to determine a value of the kth bit of the modulation symbol ^, and when the ^=0, determine whether the error D is smaller than min_dist_0[k], in the error When D is smaller than min_dist_0[k], the value of min_dist_0[k] is equal to the error D, and when the error D is greater than or equal to min_dist_0[k], min_dist_0[k] is not updated; or in the ^=1, judging Whether the error D is smaller than min_dist_l[k], and when the error D is smaller than min_dist_l[k], let the value of min_dist_l[k] be equal to the error D, when the error D is greater than or equal to min_dist_l [k], Update min_dist_l [k].