WO2010043125A1

WO2010043125A1 - Sub-carrier mapping method of space frequency block code

Info

Publication number: WO2010043125A1
Application number: PCT/CN2009/072680
Authority: WO
Inventors: 姜静; 孙云锋; 于辉
Original assignee: 中兴通讯股份有限公司
Priority date: 2008-10-16
Filing date: 2009-07-08
Publication date: 2010-04-22
Also published as: CN101729212A; WO2010043132A1; CN101729212B

Abstract

A sub-carrier mapping method of space frequency block code (SFBC) includes that of: transmitting the first symbol sequence to be encoded by the space frequency block code through one antenna; performing operations of the conjugate operation, invert ordering, cyclic shift and phase rotation to obtain the second symbol sequence and transmitting it through the other antenna; wherein, no order relations exists between every operation, the difference between the phase rotation angles of neighbor symbols in the sequence is e ^jhπ, h is an odd number, and the number of bits of cyclic shift is an even number. The sub-carrier mapping method proposed by the invention can keep the single carrier characteristic of the transmitted symbol, may realize that the SFBC encoding has low peak-to-average power ratio (PAPR) in the uplink diversity and satisfy the system’s design need.

Description

Subcarrier mapping method for space frequency block code

Technical field

The present invention relates to a subcarrier mapping technique of a Space Frequency Block Code (SFBC), and more particularly to a subcarrier mapping method for an uplink space frequency block code.

Background technique

In the Long Term Evolution (LTE) system, user equipment (UE, User Equipment) is power-limited, requiring a low peak-to-average power ratio (PAPR) „downstream in the LTE standard. The two-antenna method - SFBC (Space Frequency Block Code) is used.

When using SFBC in the uplink, the traditional SFBC subcarrier mapping method in the multiple access mode single carrier frequency division multiplexing (SC-FDMA) currently used in LTE is as shown in Fig. 1. This mapping method disrupts the sub-carrier. The symbol arrangement after the carrier discrete Fourier transform (DFT) destroys the single carrier characteristic of SC-FDMA and increases the PAPR of the UE. Since the subcarriers destroy the single carrier characteristics in the multiple access mode, the PAPR of the UE side is significantly increased, and thus the existing SFBC is not suitable as the uplink diversity mode.

Summary of the invention

The technical problem to be solved by the present invention is to provide a subcarrier mapping method for a space frequency block code, which improves the PAPR of the UE. In order to solve the above technical problem, the present invention provides a subcarrier mapping method for a space frequency block code, the method comprising:

Transmitting a first symbol sequence to be coded by a space frequency block code through an antenna; performing a conjugate operation, a reverse order, and a phase rotation operation on the first symbol sequence to obtain a second symbol sequence, and passing the second symbol sequence Another antenna transmits, wherein each operation has no order relationship, and an angle h of phase rotation between the second symbol sequence and the second symbol is an odd number, and a number of cyclic shift bits is an even number.

The method further includes: when obtaining the second symbol sequence according to the first symbol sequence, further The first symbol sequence is cyclically shifted.

Further, the first symbol sequence is recorded as the second symbol sequence is

2, or 2, ⁵ 1 ' * means to take the total. Further, the first symbol sequence is recorded as a cyclic shift of the number of bits n, and the second symbol sequence is -s, ,..., s _M * ,...,s _n * ₊₂ -s _n * _+l or - , ,...,-1⁄2,..·, -s _n " ₊₂ , d.

Preferably, the n value is any one of 0, 2, 4, ..., (M/2-l) * 2.

Preferably, the first symbol sequence is M symbol sequences obtained by channel coding, modulation, and M-point discrete Fourier transform of the data source.

Further, the method is specifically:

The first symbol sequence is corresponding to M subcarriers, and is mapped to the first antenna to transmit;

Performing a conjugate operation on the first symbol sequence ^^ to obtain 4, and sorting the sequence "4 in reverse order to obtain 4, 4 - 4-2, ..., 4;

For the sequence 4,4— ,, 4—2,..., 4 cyclic shift, the number of bits of the cyclic shift n, the shifted sequence is

After phase rotation of the sequence... _{+2 +1} , it is mapped to the second antenna transmission, and the sequence of transmission is -d,...,^,...,^,-^, where k=0,l, ..., Ml.

Further, the method is specifically:

The symbol sequence to be encoded by SFBC is mapped to the M subcarriers, and is mapped to the first antenna for transmission, and the transmitted symbol is

The SFBC coding sequence of symbols to be performed _¾ conjugate operation, to give

,^2,^3,+ + +,3⁄4"1, ⁵ Μ '

The obtained sequences « , ..., are arranged in reverse order to obtain 4, 4 - , , 4 - ₂ , ..., 4 ; for the obtained sequences 4, 4 -, 4 - ₂ , ..., « After the phase rotation ^, a second symbol sequence is obtained, and the second transmitting antenna is mapped, and the second symbol sequence transmitted is -^-^^,...,^,-^, where k=0, 1, .. .Ml. Preferably, the phase rotation of the sequences 4, 4 - , , 4 - ₂ , ..., 4 is as follows: -;

The subcarrier mapping method proposed by the present invention performs the two antenna diversity in the uplink, so that the symbols transmitted on one antenna are completely arranged according to the symbols after the DFT, and the symbols transmitted by the other antenna are arranged according to the Fourier transform property, and the transmission symbols are kept. The single carrier feature enables SFBC coding to achieve low PAPR in the uplink diversity, meeting system design needs.

BRIEF abstract

Figure 1 shows the traditional SFBC mapping method;

2 is a SFBC mapping method according to Embodiment 1 of the present invention;

FIG. 3 is a schematic diagram of an SFBC mapping method according to Embodiment 2 of the present invention.

Preferred embodiment of the invention

The basic idea of the present invention is: when performing uplink two antenna diversity, the symbols transmitted on one antenna are completely arranged according to the symbols after the DFT, and the symbols transmitted by the other antenna are arranged according to the Fourier transform property, and the symbols after the DFT are arranged. After performing the conjugate operation, the reverse order arrangement, the cyclic shift and the phase rotation operation, the symbol sequence is transmitted through another antenna, wherein each operation has no order relationship, and the angles of the phase rotations of adjacent symbols in the sequence are different, and the number is odd, loop The number of bits shifted is an even number, and the number of bits that are not cyclically shifted or cyclically shifted is zero.

The specific implementation of the present invention will be further described in detail below with reference to the accompanying drawings.

The subcarrier mapping method of the SFBC according to the first embodiment of the present invention includes the following steps:

Step 210: The symbol sequence to be encoded by the SFBC is mapped to the M subcarriers, and is mapped to the first antenna for transmission.

The following step is to obtain the second symbol sequence of the SFBC by using the foregoing symbol sequence, specifically: Step 220, performing a conjugate operation on the symbol sequence to be SFBC encoded.

Step 230, and then sorting the sequence «, ,..., 4 4 in reverse order, and obtaining ^ Among them, the symbol sequence obtained by M-point DFT transform is conjugated, and then the reverse order is 4,4— , 4— ₂ , . . . , 4 does not affect the PAPR after its inverse fast Fourier transform (IFFT). value.

Step 240: Perform phase rotation on the sequence to obtain a second symbol sequence, where k has a value of 0, 1, ..., M-1, and maps a second transmit antenna to transmit, and the second symbol sequence transmitted is

^S M ·> ~ ^S M-\ ·> ^S M-2 ->---> ^S 2-> ~ ^S \,

Sequence of pairs

The details are as follows: wherein the sequence mapped to the second transmit antenna may also be

~ ^S M -> ^S M-\-> ~ ^S M-2 ·>····> ~ ^S 2 ·> ^S \,

Another Bu Xi, ₂ to 4,4, ..., 4 is not limited to the phase rotation e ^, other angles of rotation may be, the phase angle between the rotation as long as the second symbol sequence with the sequence of symbols to be encoded difference SFBC ^" can, where h is an odd number, j ² =-l.

Here, it should be noted that the order of performing the conjugate calculation, the reverse order, and the phase rotation is not fixed, and these operations can be performed in an arbitrary order.

Because of the sequence ^, ^—^! ^,... Perform phase rotation without changing its DFT characteristics, so 4, -4 - ₁ , 4 - ₂ , ..., 4- and send ^..., 1⁄2_ ₂ , 3⁄4_ ₁ , 3⁄4 at 0 ^ After Ding? The ^1 values are equal.

It can be seen that the data source is SFBC encoded by channel coding, modulation, M-point DFT-transformed M symbols, s ₂ , ..., s _M

The matrix of the time-coded block code becomes: * * keeps the positive of the transmitted symbol

Interacting does not change the diversity gain of SFBC.

Therefore, the SFBC code subjected to the above subcarrier mapping still maintains the same PAPR as the single carrier after the IFFT transform, and can achieve a low PAPR like the cyclic delay diversity (CDD), but it is proved that a large number of simulation results are available. Better than CDD, Space-time block code (STBC), Frequency Conversion Transmit Diversity (FSTD) diversity performance. The SFBC subcarrier mapping method in the second embodiment of the present invention includes the following steps:

Step 310: Set the M symbols to be SFBC-encoded by the channel coding, modulation, and M-point DFT transform as corresponding M sub-carriers, and map to the first antenna to transmit, and the transmitted symbol is

The design of the system is usually designed with an even number of M.

The steps of the second symbol sequence obtained by the above SFBC symbol sequence specifically is: step 320, conjugating operation _¾, denoted as 44;

Step 330, arranging the sequence in reverse order, and obtaining -^, ..., ^; Step 340, cyclically shifting the above sequence 4, 4 - , , 4 4 , the number of bits of the cyclic shift "e{0, 2, 4 ,...,(M/2- 1)*2} , the shifted sequence is ^ ..., ^ ... ₊₂ , d , where the cyclic shift does not change its PAPR value.

Step 350, after performing phase rotation on the sequence, k=0, l, ..., Ml, mapping to the second antenna transmission, the sequence of transmission is -^,...,-^,... ₊₂ , - .

The sequence of the transmission may also be 4,..., - ₂ , d.

In addition, the phase rotation of ^, . . . , ^ ... _{+2 +1} is not limited to rotating other angles, as long as the angle of phase rotation between the second symbol sequence and the symbol sequence to be SFBC encoded is guaranteed to be different. , h is an odd number, j ² =-l.

Application examples of the invention

In this example, the sequence after the cyclic shift is 1⁄2/2,1⁄2/2-l— -^2^1 , — ·,1⁄2/2 ₊ 2,1⁄2/2 ₊ 1 , after phase rotation of the sequence, k=0, 1 , ... , M -1; Map to the second antenna for transmission, the sequence of transmission is /2, - /2 - 1, , ··Ά, - ^1, , -1,"", /2+2,- /2 +1 ' or

— ^S M I2, ^S M l2-\"'-', — ^S 2, ^S \ - >~ ^S M M-1 " * * * ~ ^S M ί 2+2 ' ^S M ί 2+1 °

Here, it should be noted that the order of performing the conjugate calculation, the reverse order arrangement, the cyclic shift, and the phase rotation is not fixed, and these operations can be performed in an arbitrary order.

The subcarrier mapping method of the SFBC according to the present invention enables the SFBC to maintain the characteristics of Alamouti orthogonal coding in the LTE/Long Term Evolution advanced system (LTE-Advanced), and achieves better diversity than other diversity modes. The gain, and by the subcarrier mapping method of the present invention, can also achieve the same PAPR as in the case of a single carrier.

The above description is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.

Industrial applicability

The subcarrier mapping method proposed by the present invention performs the two antenna diversity in the uplink, so that the symbols transmitted on one antenna are completely arranged according to the symbols after the DFT, and the symbols transmitted by the other antenna are arranged according to the Fourier transform property, and the transmission symbols are kept. The single carrier characteristic enables SFBC coding to achieve low PAPR in the uplink diversity, which satisfies the system design requirements, and therefore has strong industrial applicability.

Claims

Claim

A subcarrier mapping method for a space frequency block code, the method comprising:

2. The method of claim 1, wherein the method further comprises cyclically shifting the first sequence of symbols when the second sequence of symbols is derived from the first sequence of symbols.

3. The method according to claim 1 or 2, wherein the first symbol sequence is recorded as

The second symbol sequence is 1, 4 - 2, ..., 4_ or -4, 4 - _4 - ₂ , ..., - 4 ' * represents a conjugate.

4. The method according to claim 1 or 2, wherein the first symbol sequence is recorded as

The number of bits of the cyclic shift is n, then the second sequence of symbols is ^... ,...,^,-^

s _n _, -s _n+2 , s _n+ .

The method according to claim 4, wherein the n value is any one of 0, 2, 4, ..., (M/2-l) * 2 .

The method according to claim 1 or 2, wherein the first symbol sequence is M symbol sequences obtained by channel coding, modulation, and M-point discrete Fourier transform of the data source.

The method according to claim 2, wherein the method is specifically:

Performing a conjugate operation on the first symbol sequence ^^ to obtain 4, and sorting the sequence "4 in reverse order to obtain 4, 4 - 4 -, ..., 4;

For the sequence 4,4— , , 4 4 cyclic shift, the number of bits of the cyclic shift n, the shifted sequence is

^S n -> ^S n-\ -> - - - -> ^S M ·> · · · ·> ^S n^2 -> ^S n^\!

After phase rotation of the sequence... _{+2 +1} , map to the second antenna The sequence of shots emitted is ^..., ,..., ,- , where k=0,l,...,Ml.

8. The method according to claim 1, wherein the method is specifically:

The symbol sequence to be encoded by SFBC is mapped to M subcarriers, and is mapped to the first antenna for transmission, and the transmitted symbol is ...,

The SFBC coding sequence of symbols to be _½ for the conjugate operation, to give

^1, , ^3, ..., ^S Ml, ^S M ,

Sequence «obtained, ..., a reverse order, to give · ^ • d ^^; sequences obtained after _{4, 'd, 4- 2,} ..., 4' to obtain a second phase-rotated symbol sequence Mapping the second transmit antenna to transmit, and transmitting the second symbol sequence is ^, -^-^/^, ..., -^, where k=0, 1, ... Ml.

9. The method according to claim 8, wherein the phase rotation of the sequence 3⁄4, - _ ₁₅ 1⁄2-2; -^2^» is as follows: ^{e 3 S} M ·> ^{e JS} M-\ ·> ^{β 3 S} M-2,',', ^{e 3 ( S} 2-> ^{e 3 (} = 3⁄41/, a ' 1, 2, + + ., ^, — ' °