CN101183919B - Self-adaptive mixture automatic request retransmission method - Google Patents

Abstract

The invention discloses a combined hybrid automatic repeat request (HARQ) method, belonging to the field of wireless communication technology, aiming to effectively reduce the signal error rate, reduce retransmission number and increase throughout rate. The utility model is characterized that: a data transmission link is established between the sending end and the receiving end, the channel coding and the space-time coding structure are cascade connected; wherein, the number of the transmitting antenna at the sending end M is larger than one, M constellations or M kinds of bit sequence are stored at the sending end and the receiving end; one constellation is mapped or a bit sequence is rearranged and then mapped on a fixed constellation before each retransmission; then space-time coding is done according to a space-time coding structure; finally soft information combination and iterative decoding is done at the receiving end. The utility model has an advantage that the antenna diversity gain and the bit-symbol mapping diversity gain can effectively reduce the retransmission number and optimize system performance.

Description

The automatic request retransmission method of a kind of mixing of combination

Technical field

The invention belongs to wireless communication technology, relate in particular to the automatic request retransmission method of mixing of a kind of combination in multiaerial system.

Background technology

The wireless communication system expectation can obtain higher message transmission rate and the reliability of Geng Gao, yet the multipath fading characteristic limitations of wireless channel the performance of system, empty time-code is the many multi-antenna technologies through decline of a kind of antagonism effectively, roughly can be divided into two big classes: a class is the empty time-code based on space diversity, grid code at one's leisure (STTC) commonly used and Space-Time Block Coding (STBC); One class is the empty time-code based on spatial reuse, and hierarchical space-time code (BLAST) is arranged.Chnnel coding (as LDPC, the TURBO sign indicating number) adopts the iterative decoding mode through Bit Interleave, can obtain good error performance.Even so, wireless communication system still needs a kind of automatic request retransmission (ARQ) agreement to ensure the reliable transmission of packet.

Mix automatic request retransmission (HARQ) technology and make full use of the useful information that retransmits in the code word, and in different ways these useful informations are merged, thereby reduce number of retransmissions effectively, system can obtain the performance more excellent than traditional ARQ.On the one hand, HARQ almost can guarantee the error free transmission of data, and on the other hand, HARQ can reduce the capacity of system greatly.So consideration will mix automatic request retransmission (HARQ) and advance to have more that (MIMO) combine will be very effective and significant more.

In radio communication,, need to use the spectral efficient modulation technique for supporting higher speed rates.Along with the further investigation to the spectral efficient communication system, various non-self-adaptings and adaptive high-order orthogonal amplitude modulation(PAM) (MQAM) technology are subjected to extensive attention in radio communication.But because the different bits that MQAM modulates modulation symbol provide different error protections, the data that make receiving terminal separate the output of mapping back have the reliability that does not wait, and this will reduce the error-correcting performance at the Turbo code of equal reliability data decoding.Japan Matsushita Electronics Industries Ltd; the international patent application that No. 02067491 name of WO is called " having the hybrid ARQ method that various constellations figure resets " was proposed on August 29th, 2002; invented HARQ scheme with signal constellation which rearrangement at the HARQ system of 16QAM and 64QAM modulation system; unequal error protection characteristic according to the QAM modulation has proposed the even planisphere that several different bits arrive sign map; transmission with retransmit in adopt different planispheres to modulate mapping and separate mapping; perhaps bit is reset to conciliate accordingly and reset; make the data that after retransmit merging, are sent to Turbo decoder input at receiving terminal have identical reliability, improve the throughput of HARQ system.This method can improve the high efficiency of decoding, thereby reduces error rate.But this re-transmission merging mechanism is based on the chase merging, the promptly each identical symbol of employing, diversity gain that makes full use of many antennas useless of retransmitting.

Summary of the invention

The invention provides a kind of automatic request retransmission method of mixing of combination, purpose is to reduce effectively the error rate of symbol, thereby reduces number of retransmissions, improves the throughput of system.

The automatic request retransmission method of the mixing of a kind of combination of the present invention is set up data transmission link at transmitting terminal and receiving terminal, and M is greater than 1 for the transmitting terminal number of transmit antennas, and a transmitting terminal and a receiving terminal store M planisphere or M kind bit arrangement order are carried out following step:

(1) transmitting terminal is prepared new data, and the data order is carried out error detection coding, chnnel coding, Bit Interleave, is stored in the transmission buffer area, and the NACK number is initialized as 0;

(2) transmitting terminal then discharges current data by ACK, commentaries on classics step (1) if receive from buffer area; Otherwise change step (3);

(3) transmitting terminal is put transmission sequence number N=NACK number+1;

(4) the N time transmission of transmitting terminal is if transmission sequence number N greater than number of transmit antennas M, changes step (5); Otherwise, from the planisphere that transmitting terminal stores, select N planisphere, the bit sequence that sends the buffer area storage is shone upon, perhaps from the bit arrangement order that transmitting terminal stores, select N kind bit arrangement order, carry out fixed signs figure mapping again after the bit sequence that stores in the buffer area is reset sending; Data after the mapping are encoded by the N row of quasi-orthogonal empty time-code battle array, send packet, change step (6);

(5) transmitting terminal carries out modulo operation with N to M, upgrades the N value, changes step (4);

(6) receiving terminal receives data, and carries out MIMO and detect;

(7) receiving terminal selects N the planisphere consistent with transmitting terminal to separate mapping, perhaps recover to carry out fixed signs diagram mapping again after the bit arrangement order, obtain current bit soft information, be log-likelihood ratio, and be stored in and receive in the buffer area, and merge with all bit soft information of former storage;

(8) all bit soft information of receiving terminal utilization merging are carried out iterative decoding;

(9) receiving terminal carries out error checking and correction with decoded information, if correct, carries out step (10), otherwise changes step (11);

(10) the receiving terminal feeding back ACK is given transmitting terminal, changes step (2);

(11) receiving terminal feedback NACK gives transmitting terminal, changes step (2).

The automatic request retransmission method of the mixing of described a kind of combination, it is characterized in that, a described M planisphere be Gray coding the high-order orthogonal amplitude modulation(PAM) even planisphere and reset on this basis after M-1 planisphere, the selection rule of this M-1 planisphere is: in all planispheres after the even Constellation Rearrangement of the high-order orthogonal amplitude modulation(PAM) of encoding based on Gray, choose M-1 planisphere, can make the soft information between each bit that is mapped on this M planisphere merge value difference opposite sex minimum, i.e. reliability difference minimum; Described M kind bit arrangement order is arranged entirely for original bit is put in order, and therefrom chooses M kind bit arrangement order, makes that the soft information between each bit merges value difference opposite sex minimum, i.e. reliability difference minimum.

The automatic request retransmission method of the mixing of described a kind of combination is characterized in that, the fixed signs figure described in described step (4) and the step (7) is the even planisphere of the high-order orthogonal amplitude modulation(PAM) of Gray coding.

Code structure was as in-line coding when the present invention will be based on diversity gain empty, Constellation Rearrangement and chnnel coding are combined, simultaneously the transmission data are carried out symbol in rearrangement on the antenna and the rearrangement between bit, can obtain the gain of two aspects, utilize the soft value of information after merging to carry out iterative decoding, can reduce number of retransmissions effectively, the optimization system performance.

Description of drawings

Fig. 1 is a FB(flow block) of the present invention;

Fig. 2 (A)～Fig. 2 (D) is 4 types planisphere of 16QAM modulation;

Fig. 2 (A) is a planisphere 1;

Fig. 2 (B) is a planisphere 2;

Fig. 2 (C) is a planisphere 3;

Fig. 2 (D) is a planisphere 4.

Embodiment

The example that the present invention adopts is: the mimo system of 4 transmitting antennas, 4 reception antennas, and chnnel coding adopts Turbo code, and modulation system adopts 1 6QAM, and empty time-code adopts the quasiorthogonal code structure of ABBA type commonly used.

The sign indicating number battle array structure of the quasiorthogonal code of ABBA type, as follows:

$\left(\begin{array}{cccc}{x}_1& {-x}_2^{*}& x_3& {-x}_4^{*}\\ x_2& x_1^{*}& x_4& x_3^{*}\\ x_3& {-x}_4^{*}& x_1& {-x}_2^{*}\\ x_4& x_3^{*}& x_2& x_1^{*}\end{array}\right)\·$

The empty time-code of ABBA type is the matrix structure of M * p, and wherein M is a number of transmit antennas, and p is the symbol timeslot number.The symbolic vector of transmitting on corresponding each the symbol time slot of the every row of matrix, the transmission symbol on the corresponding every transmit antennas of every row.

It is as shown in table 1 that 4 planispheres selecting that transmitting terminal stores or 4 kinds of bit arrangement reach the empty time-code row corresponding with it in proper order, 4 planispheres that Fig. 2 (A)～Fig. 2 (D) modulates for 16QAM; The fixed signs figure that this example adopts is shown in Fig. 2 (A).In these four planispheres, with per 4 bit c _I1c _I2c _I3c _I4Be mapped to the complex symbol z={z of a 16QAM _I, z _Q, z _I, z _Q∈ { ± Δ ₁, ± Δ ₂, wherein ${\mathrm{\Δ}}_1^2+{\mathrm{\Δ}}_2^2=1,$ Δ ₂＝2Δ ₁。z _IBy two bit c that are sent to the I road _I1c _I3Mapping, z _QBy two bit c that are sent to the Q road _I2c _I4Mapping.Shown in Fig. 2 (A), in bit sequence 1011, bit 11 is mapped as-Δ ₂, bit 01 is mapped as Δ ₂, then 1011 be mapped to complex symbol-Δ ₂+ j Δ ₂, similarly, bit 0001 is mapped to the complex symbol Δ ₁+ j Δ ₂According to above-mentioned rule, each planisphere becomes 16 complex symbols with 16 4 bit sequences.

Table 1: transmitting terminal is reset mode and Space Time Coding mode (16QAM)

Below to adopt the bit rearrangement mode to describe this example in detail.Suppose that wherein the bit original alignment is c in proper order _I1c _I2c _I3c _I4,

(c _IjBe 0 or 1) be the negate computing.The 1st kind of bit arrangement is c in proper order _I1c _I2c _I3c _I4The 2nd kind of bit arrangement is in proper order

The 3rd kind of bit arrangement is c in proper order _I3c _I4c _I1c _I2The 4th kind of bit arrangement is in proper order

The whole system workflow is as shown in Figure 1:

(1) transmitting terminal is prepared new data, and order carries out error detection coding, chnnel coding, be stored in the buffer area after interweaving, and the bit sequence that stores in the note buffer area is C=(c ₁₁, c ₁₂, c ₁₃, c ₁₄, c ₂₂, c ₂₃, c ₂₄...), per 4 information bits are divided into one group, remember that a binary character is c ₁=c ₁₁c ₁₂c ₁₃c ₁₄

(2) transmitting terminal then discharges current data by ACK, commentaries on classics step (1) if receive from buffer area; Otherwise change step (3);

(3) transmitting terminal is put transmission sequence number N=NACK number+1;

(4) the N time transmission of transmitting terminal is if transmission sequence number N greater than 4, changes step (5); If N=1 selects first kind of bit arrangement mode, promptly by former bit arrangement order c ₁=c ₁₁c ₁₂c ₁₃c ₁₄After carrying out fixed signs figure mapping, encode by first of empty time-code battle array; If N=2 with the bit sequence rearrangement is $c_1^{\′}=c_{13}{c}_{14}\stackrel{\‾}{c_{11}{c}_{12}},$ Carry out encoding by the secondary series of empty time-code battle array after the fixed signs figure mapping; If N=3, it is c that bit sequence is reset ₁"=c ₁₃c ₁₄c ₁₁c ₁₂, carry out after the fixed signs figure mapping, encode by the 3rd row of empty time-code battle array; If N=4 with the bit sequence rearrangement is $c_1^{\′\′\′}=c_{11}{c}_{12}\stackrel{\‾}{c_{13}{c}_{14}},$ Carry out after the fixed signs figure mapping, encode, send data, change step (6) by the 4th row of empty time-code battle array;

(5) transmitting terminal carries out modulo operation with N to 4, upgrades the N value, changes step (4);

(6) receiving terminal receives data, and carries out MIMO and detect, and detection method is as follows:

Remember transmission code vector first ${\stackrel{\&RightArrow;}{x}}_1={(x_1,x_2,x_3,x_4)}^T,$ The note channel coefficient matrix is designated as H=(h ₁, h ₂, h ₃, h ₄), h wherein _iBe n _RThe column vector of (reception antenna number) dimension, noise is designated as v, receives vector to be ${\stackrel{\&RightArrow;}{r}}_1=H{\stackrel{\&RightArrow;}{x}}_1+v_1,$ Adopt the serial interference elimination methods such as (OSIC) of ordering to detect.Note is transmitted code vector for the second time ${\stackrel{\&RightArrow;}{x}}_2={(-x_2^{*},x_1^{*},-x_4^{*},x_3^{*})}^T,$ The reception vector is designated as ${\stackrel{\&RightArrow;}{r}}_2=H{\stackrel{\&RightArrow;}{x}}_2+{\mathrm{<figure-callout\; id="2"\; label="v"\; filenames="S200710168493XE00031.png"\; state="\{\{state\}\}">v</figure-callout>}}_2\&CenterDot;$

${{\stackrel{\&RightArrow;}{r}}_2}^{*}=(-h_2^{*}{h}_1^{*}-h_4^{*}{h}_3^{*})\left(\begin{array}{c}{x}_1\\ x_2\\ x_3\\ x_4\end{array}\right)+v^{\&prime;}$ (1)

Note ${\stackrel{\&RightArrow;}{r}}^{\&prime;}={{\stackrel{\&RightArrow;}{r}}_2}^{*},$ $H^{\&prime;}=(-{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="S200710168493XE00031.png"\; state="\{\{state\}\}">h</figure-callout>}}_2^{*}{h}_1^{*}-h_4^{*}{h}_3^{*}),$

Then (1) formula is converted into

${\stackrel{\&RightArrow;}{r}}^{\&prime;}=H^{\&prime;}\stackrel{\&RightArrow;}{x}+v^{\&prime;},$ (2)

So far, can take method such as OSIC to detect (2) formula.

For for the third time with the 4th time the transmission detection mode can the rest may be inferred.

Carry out this reception vector and the reception vector of N=N mod 4 times transmission after chase merges the number of transmissions N＞4, uses method such as OSIC to detect again.

(7) receiving terminal recovers to adopt fixed signs diagram mapping again after the bit arrangement order, obtains current bit soft information, i.e. log-likelihood ratio, and be stored in and receive in the buffer area, and with all bit soft information merging of former storage;

(8) bit soft information of receiving terminal utilization merging is carried out iterative decoding, and the iterative decoding method is described below:

All re-transmissions merge the bit soft information that obtains and are designated as L (d), and the bit soft information that outputs to behind the Bit Interleave in the buffer memory is designated as L _a(d), then buffer area is exported L _e(d)=L (d)-L _a(d), soft information via and string conversion with output through after the deinterleaving, obtain L _a(c), with L _a(c) output to channel decoder, obtain new bit soft information L (c), L _e(c)=L (c)-L _a(c) through after interweaving, carry out serial to parallel conversion and obtain L _a(d), be input to the iteration of carrying out in the buffer area next time.When iterations reaches, channel decoder output hard decision information L (b).

(9) receiving terminal carries out error checking and correction with decoded output information, if correct, carries out step (10), otherwise changes step (11);

(10) the receiving terminal feeding back ACK is given transmitting terminal, changes step (2);

(11) receiving terminal feedback NACK gives transmitting terminal, changes step (2).

Claims (3)

1. the automatic request retransmission method of the mixing of a combination is set up data transmission link at transmitting terminal and receiving terminal, and M is greater than 1 for the transmitting terminal number of transmit antennas, and a transmitting terminal and a receiving terminal store M planisphere or M kind bit arrangement order are carried out following step:

(1) transmitting terminal is prepared new data, and the data order is carried out error detection coding, chnnel coding, Bit Interleave, is stored in the transmission buffer area, and the NACK number is initialized as 0;

(2) transmitting terminal then discharges current data by ACK, commentaries on classics step (1) if receive from buffer area; Otherwise change step (3);

(3) transmitting terminal is put transmission sequence number N=NACK number+1;

(4) the N time transmission of transmitting terminal is if transmission sequence number N greater than number of transmit antennas M, changes step (5); Otherwise, from the planisphere that transmitting terminal stores, select N planisphere, the bit sequence that sends the buffer area storage is shone upon, perhaps from the bit arrangement order that transmitting terminal stores, select N kind bit arrangement order, carry out fixed signs figure mapping again after the bit sequence that stores in the buffer area is reset sending; Data after the mapping are encoded by the N row of quasi-orthogonal empty time-code battle array, send packet, change step (6);

(5) transmitting terminal carries out modulo operation with N to M, upgrades the N value, changes step (4);

(6) receiving terminal receives data, and carries out MIMO and detect;

(7) receiving terminal selects N corresponding planisphere to separate mapping, perhaps recover to carry out fixed signs diagram mapping again after the bit arrangement order, obtain current bit soft information, i.e. log-likelihood ratio, and be stored in and receive in the buffer area, and merge with all bit soft information of former storage;

(8) all bit soft information of receiving terminal utilization merging are carried out iterative decoding;

(9) receiving terminal carries out error checking and correction with decoded information, if correct, carries out step (10), otherwise changes step (11);

(10) the receiving terminal feeding back ACK is given transmitting terminal, changes step (2);

(11) receiving terminal feedback NACK gives transmitting terminal, changes step (2).

2. the automatic request retransmission method of the mixing of a kind of combination as claimed in claim 1, it is characterized in that, a described M planisphere be Gray coding the high-order orthogonal amplitude modulation(PAM) even planisphere and reset on this basis after M-1 planisphere, the selection rule of this M-1 planisphere is: in all planispheres after the even Constellation Rearrangement of the high-order orthogonal amplitude modulation(PAM) of encoding based on Gray, choose M-1 planisphere, can make the soft information between each bit that is mapped on this M planisphere merge value difference opposite sex minimum, i.e. reliability difference minimum; Described M kind bit arrangement order is arranged entirely for original bit is put in order, and therefrom chooses M kind bit arrangement order, makes that the soft information between each bit merges value difference opposite sex minimum, i.e. reliability difference minimum.

3. the automatic request retransmission method of the mixing of a kind of combination as claimed in claim 1 is characterized in that, the fixed signs figure described in described step (4) and the step (7) is the even planisphere of the high-order orthogonal amplitude modulation(PAM) of Gray coding.

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