CN101777944A - Space-time frequency coding method and device - Google Patents

Abstract

The invention discloses a space-time frequency coding method, which comprises the following steps: carrying out space frequency grouping coding on signs to be sent on transmitting antennas; carrying out circulation delay diversity (CDD) coding on the signs after the space frequency grouping coding; carrying out frequency switching transmitting diversity (FSTD) processing on the signs which do not carry out CDD coding; and obtaining space-time frequency coding matrixes. The invention also discloses a space-time frequency coding device, which realizes the diversity processing on eight transmitting antennas in a long-time evolution advanced (LTE-Advanced) system. The down diversity combination of the space frequency grouping coding and the CCD coding is realized on the basis of eight transmitting antennas, different signs correspond to different transmitting antennas, the degradation influence of the pertinence of the transmitting antennas on the diversity grain is avoided, the multidimensional diversity grain is realized, and the diversity grain is improved.

Description

A kind of space-time frequency coding method and device

Technical field

The present invention relates to the diversity treatment technology in Long Term Evolution (LTE) system, relate in particular to a kind of space-time frequency coding method and device.

Background technology

In Long Term Evolution (LTE, Long Time Evolution) system, the descending transmitting antenna that defined is the diversity mode of 2 antennas and 4 antennas.Wherein, the diversity mode when transmitting antenna is 2 antennas is space frequency block coding (SFBC, Space Frequency Block Coder), and encoder matrix is shown below:

In following formula, a transmitting antenna is shown in each tabulation, tranmitting frequency of each line display; S ₁The symbol that expression first sends constantly, S ₂The symbol that expression second sends constantly, S ₁ ^*And S ₂ ^*Represent S respectively ₁And S ₂Conjugation.

The diversity mode that has defined when transmitting antenna is 4 antennas is SFBC+ frequency switched transmit diversity (FSTD, Frequency Switch Transmit Diversity), and encoder matrix is shown below:

In following formula, a transmitting antenna is shown in each tabulation, tranmitting frequency of each line display; S ₁The symbol that expression first sends constantly, S ₂The symbol that expression second sends constantly, S ₃Represent the 3rd symbol that sends constantly, S ₄Represent the 4th symbol that sends constantly,

With

Represent S respectively ₁, S ₂, S ₃And S ₄Conjugation.

In Long Term Evolution AS (LTE-Advanced, Long Term Evolution AdvancedSystem),, stipulate descendingly can use 8 transmit antennas at most in order to improve the descending message transmission rate and the availability of frequency spectrum.But in the existing standard of LTE, and the diversity mode under undefined 8 transmit antennas, therefore also can't be implemented at present in the LTE-Advanced system transfer of data, thereby make troubles to practical application based on 8 transmit antennas.

Summary of the invention

In view of this, main purpose of the present invention is to provide a kind of space-time frequency coding method and device, handles to be implemented in the LTE-Advanced system based on the diversity of 8 transmit antennas.

For achieving the above object, technical scheme of the present invention is achieved in that

The invention provides a kind of space-time frequency coding method, this method comprises:

Symbol to be sent on the transmitting antenna is carried out space frequency block coding;

To circulate delay diversity CDD coding of the symbol behind the space frequency block coding;

The symbol that does not carry out described CDD coding is carried out frequency switched transmit diversity FSTD handle, obtain the space-time frequency coding matrix.

Describedly symbol to be sent on the transmitting antenna is carried out space frequency block coding specifically comprise: described symbol to be sent is carried out adjacent grouping in twos, and described space frequency block coding is carried out in grouping.

The described CDD coding that carries out specifically comprises:

Will be with Ah coming certain carry Alamouti and be encoded to the minimum unit of the space frequency block coding on basis as described CDD coding, and each Alamouti coding that space frequency block coding is constituted is to carrying out the CDD operation.

Described CDD coding further comprises: the right symbol of Alamouti coding is carried out the CDD operation, and the symbol that carries out after CDD operates sends on two antenna ports.

Described FSTD handles and specifically comprises: the Alamouti coding that does not carry out the CDD operation is handled carrying out FSTD, and promptly different Alamouti codings is to sending on different antenna ports, and same Alamouti coding is to sending on identical antenna port; Symbol through the CDD encoding process does not carry out the FSTD processing.

Described different Alamouti coding is to sending being spaced apart on 4 the different antennae port.

The present invention also provides a kind of space-time frequency coding device, comprising:

First coding module is used for symbol to be sent on the transmitting antenna is carried out space frequency block coding;

Second coding module is used for circulate delay diversity CDD coding of the symbol behind the space frequency block coding;

The FSTD processing module is used for obtaining the space-time frequency coding matrix to handling for the symbol that carries out described CDD coding carries out FSTD.

Space-time frequency coding method provided by the present invention and device at first carry out the SFBC coding to symbol to be sent on the transmitting antenna, again the symbol behind the SFBC coding are carried out the CDD coding; Then the symbol that does not carry out the CDD coding is carried out FSTD and handle, obtain the space-time frequency coding matrix.The present invention is in the LTE-Advanced system, encode in conjunction with SFBC coding and CCD based on the descending diversity of 8 transmit antennas, the transmitting antenna that different symbols is corresponding different, avoided the degradation impacts of transmit antenna correlation to diversity gain, realize the diversity gain of various dimensions, improved diversity gain.

Description of drawings

Fig. 1 is the flow chart of a kind of space-time frequency coding method of the present invention;

Fig. 2 is the composition structural representation of a kind of space-time frequency coding device of the present invention.

Embodiment

The technical solution of the present invention is further elaborated below in conjunction with the drawings and specific embodiments.

The present invention has proposed a kind of space-time frequency coding method in order to realize in the LTE-Advanced system based on the diversity processing mode of 8 transmitting antennas, and as shown in Figure 1, this method mainly may further comprise the steps:

Step 101 is carried out the SFBC coding to symbol to be sent on the transmitting antenna.

For example, symbol to be sent is as shown in table 1 on the transmitting antenna:

S 8

S 7

S 6

S 5

S 4

S 3

S 2

S 1

Table 1

S in the table 1 ₁, S ₂, S ₃, S ₄, S ₅, S ₆, S ₇And S ₈Represent distinct symbols to be sent respectively, each symbol is carried out the SFBC coding, it is right that promptly adjacent-symbol becomes the Alamouti coding, and the coded identification inner product of two antenna transmission is 0, promptly

$\left[\begin{array}{cc}{S}_1& -S_2^{*}\end{array}\right]\·{\left[\begin{array}{cc}{S}_2& S_1^{*}\end{array}\right]}^H=S_1{S}_2^{*}-S_2^{*}{S}_1=0;$

As shown in table 2 behind the SFBC coding to symbol:

Table 2

In the table 2 With Represent S respectively ₁, S ₂, S ₃, S ₄, S ₅, S ₆, S ₇And S ₈Conjugation.

Step 102, to the delay diversity (CDD that circulates of the symbol behind the SFBC coding, CirculateDelayed Diversity) coding, promptly the signal that sends on certain root antenna is carried out the cycle time-delay τ of time domain, be equivalent to that IFFT (inverse-Fourier transform) is preceding to carry out the phase place rotation at frequency domain to the signal of this antenna transmission.

Because the order at wireless channel is 1 o'clock, certain method of carrying (Alamouti) Space Time Coding of Ah coming can reach the channel capacity upper limit, obtains maximum diversity gain, therefore, the present invention adopts Alamouti to be encoded to the minimum unit of the SFBC coding on basis as the CDD coding, as:

In the array of 8 transmitting antennas, antenna distance is generally the half-wavelength of antenna tranmitting frequency, and this moment, the correlation of transmitting antenna array was very strong.Because in the diversity technique of LTE, Antenna Correlation is to the not significantly influence of diversity gain of CDD, therefore, the present invention carries out the CDD coding to the adjacent transmission antenna, thereby can reduce the relevant diversity gain degradation impacts that is caused of transmitting antenna array channel.

In above-mentioned table 2

It is right to constitute an Alamouti coding,

It is right to constitute an Alamouti coding,

It is right to constitute an Alamouti coding,

It is right to constitute an Alamouti coding; To the time-delay τ that circulates of the symbol behind the Alamouti coding ₁, τ ₁≠ 0, promptly k subcarrier of frequency domain carries out phase-shift processing

The matrix that obtains after CDD encodes is:

$\left[\begin{array}{cccc}{s}_1& s_1{e}^{j2\mathrm{\πk}{\mathrm{\τ}}_1/N}& -s_2^{*}& -s_2^{*}{e}^{j2\mathrm{\πk}{\mathrm{\τ}}_1/N}\\ s_2& s_2{e}^{j2\mathrm{\π}(k+1){\mathrm{\τ}}_1/N}& s_1^{*}& s_1^{*}{e}^{j2\mathrm{\π}(k+1){\mathrm{\τ}}_1/N}\\ s_3& s_3{e}^{j2\mathrm{\π}(k+2){\mathrm{\τ}}_1/N}& -s_4^{*}& -s_4^{*}{e}^{j2\mathrm{\π}(k+2){\mathrm{\τ}}_1/N}\\ s_4& s_4{e}^{j2\mathrm{\π}(k+3){\mathrm{\τ}}_1/N}& s_3^{*}& s_3^{*}{e}^{j2\mathrm{\π}(k+3){\mathrm{\τ}}_1/N}\\ s_5& s_5{e}^{j2\mathrm{\π}(k+4){\mathrm{\τ}}_1/N}& -s_6^{*}& -s_6^{*}{e}^{j2\mathrm{\π}(k+4){\mathrm{\τ}}_1/N}\\ s_6& s_6{e}^{j2\mathrm{\π}(k+5){\mathrm{\τ}}_1/N}& s_5^{*}& s_5^{*}{e}^{j2\mathrm{\π}(k+5){\mathrm{\τ}}_1/N}\\ s_7& s_7{e}^{j2\mathrm{\π}(k+6){\mathrm{\τ}}_1/N}& -s_8^{*}& -s_8^{*}{e}^{j2\mathrm{\π}(k+6){\mathrm{\τ}}_1/N}\\ s_8& s_8{e}^{j2\mathrm{\π}(k+7){\mathrm{\τ}}_1/N}& s_7^{*}& s_7^{*}{e}^{j2\mathrm{\π}(k+7){\mathrm{\τ}}_1/N}\end{array}\right]$

In following formula, N represents counting of inverse-Fourier transform, and k represents k subcarrier; On every antenna of time domain, be time delay τ, be equivalent to the phase place rotation k τ/N on k subcarrier of frequency domain.

Step 103 is carried out FSTD to the symbol that does not carry out the CDD coding and is handled, and obtains the space-time frequency coding matrix.

Owing on 8 transmit antennas ports, send the symbol that diversity is handled simultaneously, can make the decoding of terminal very complicated, and FSTD not only can reduce the complexity of decoding, can also bring certain frequency diversity gain, therefore, the present invention carries out the FSTD processing to the symbol that does not carry out the CDD operation.Among the present invention the Alamouti coding that does not carry out the CDD coding is handled carrying out FSTD, promptly different Alamouti codings is to sending on different antenna ports, and same Alamouti coding is to sending on identical antenna port; Symbol through the CDD encoding process does not carry out the FSTD processing.

Carry out CDD with above-mentioned selection antenna 4 and antenna 8 and be encoded to example, symbol in antenna port 1, antenna port 2, antenna port 3, antenna port 5, antenna port 6 and the antenna port 7 does not carry out the CDD coding, it is carried out FSTD handle, each same treatment Alamouti coding sends 4 antenna ports of being separated by.The space-time frequency coding matrix that obtains is:

In the following formula, each row is represented a transmitting antenna, a subcarrier or an OFDM (OFDM that on behalf of the Space Time Coding symbol, each row send, Orthogonal Frequency DivisionMultiplexing) symbol, N represents counting of inverse-Fourier transform, and k represents k subcarrier; On every antenna of time domain, be time delay τ, be equivalent to the phase place rotation k τ/N on each subcarrier of frequency domain.

Handle based on two subcarriers in the subcarrier are carried out FSTD for one group, but the symbol that CDD handles is not carried out the principle that FSTD handles, subcarrier k and subcarrier k+1 send the symbol of first group of SFBC on antenna port 1 and antenna port 5; Subcarrier k+2 and subcarrier k+3 send the symbol of second group of SFBC on antenna port 2 and antenna port 6; Subcarrier k+4 and subcarrier k+5 send the symbol of the 3rd group of SFBC on antenna port 3 and antenna port 7; Subcarrier k+6 and subcarrier k+7 send the symbol of the 4th group of SFBC on antenna port 1 and antenna port 5.Symbol after CDD handles sends on antenna port 4 and antenna port 8.

Certainly, to the symbol that does not carry out CDD coding carry out the space-time frequency coding matrix that obtains after FSTD handles not only be confined to above-mentioned a kind of, as long as guarantee that two groups of adjacent SFBC symbols send on different antennas.For example, also can be:

In the following formula, subcarrier k and subcarrier k+1 send the symbol of first group of SFBC on antenna port 1 and antenna port 5; Subcarrier k+2 and subcarrier k+3 send the symbol of second group of SFBC on antenna port 2 and antenna port 6; Subcarrier k+4 and subcarrier k+5 send the symbol of the 3rd group of SFBC on antenna port 3 and antenna port 7; Subcarrier k+6 and subcarrier k+7 send the symbol of the 4th group of SFBC on antenna port 2 and antenna port 6.Symbol after CDD handles sends on antenna port 4 and antenna port 8.The SFBC coding of each same treatment is to 4 antenna ports transmissions at interval.

Can also be:

In the following formula, subcarrier k and subcarrier k+1 send the symbol of first group of SFBC on antenna port 1 and antenna port 5; Subcarrier k+2 and subcarrier k+3 send the symbol of second group of SFBC on antenna port 3 and antenna port 7; Subcarrier k+4 and subcarrier k+5 send the symbol of the 3rd group of SFBC on antenna port 2 and antenna port 6; Subcarrier k+6 and subcarrier k+7 send the symbol of the 4th group of SFBC on antenna port 3 and antenna port 7.Symbol after CDD handles sends on antenna port 4 and antenna port 8.The SFBC coding of each same treatment is to 4 antenna ports transmissions at interval.

Can also be:

In the following formula, subcarrier k and subcarrier k+1 send the symbol of first group of SFBC on antenna port 1 and antenna port 5; Subcarrier k+2 and subcarrier k+3 send the symbol of second group of SFBC on antenna port 4 and antenna port 8; Subcarrier k+4 and subcarrier k+5 send the symbol of the 3rd group of SFBC on antenna port 2 and antenna port 6; Subcarrier k+6 and subcarrier k+7 send the symbol of the 4th group of SFBC on antenna port 4 and antenna port 8.Symbol after CDD handles sends at antenna port 3 and antenna port 7.The SFBC coding of each same treatment is to 4 antenna ports transmissions at interval.

Similarly embodiment also has a lot, gives unnecessary details no longer one by one at this.

For realizing the space-time frequency coding method of the invention described above, the present invention also provides a kind of space-time frequency coding device, and as shown in Figure 2, this device comprises: first coding module 10, second coding module 20 and FSTD processing module 30.

Wherein, first coding module 10 is used for symbol to be sent on the transmitting antenna is carried out the SFBC coding.Second coding module 20 connects first coding module 10, is used for the symbol behind the SFBC coding is carried out the CDD coding.FSTD processing module 30 connects second coding module 20, is used for that the symbol that does not carry out the CDD coding is carried out FSTD and handles, and obtains the space-time frequency coding matrix.The principle that FSTD handles is: two subcarriers in the subcarrier are carried out FSTD for one group handle, do not handle but the symbol through the CDD encoding process is not carried out FSTD.

In sum, the present invention is in the LTE-Advanced system, encode in conjunction with SFBC coding and CCD based on the descending diversity of 8 transmit antennas, the transmitting antenna that different symbols is corresponding different, avoided the degradation impacts of transmit antenna correlation to diversity gain, realize the diversity gain of various dimensions, improved diversity gain.

The above is preferred embodiment of the present invention only, is not to be used to limit protection scope of the present invention.

Claims (7)

1. a space-time frequency coding method is characterized in that, this method comprises:

Symbol to be sent on the transmitting antenna is carried out space frequency block coding;

To circulate delay diversity CDD coding of the symbol behind the space frequency block coding;

The symbol that does not carry out described CDD coding is carried out frequency switched transmit diversity FSTD handle, obtain the space-time frequency coding matrix.

2. according to the described space-time frequency coding method of claim 1, it is characterized in that, describedly symbol to be sent on the transmitting antenna is carried out space frequency block coding specifically comprise: described symbol to be sent is carried out adjacent grouping in twos, and described space frequency block coding is carried out in grouping.

3. according to the described space-time frequency coding method of claim 1, it is characterized in that the described CDD coding that carries out specifically comprises:

Will be with Ah coming certain carry Alamouti and be encoded to the minimum unit of the space frequency block coding on basis as described CDD coding, and each Alamouti coding that space frequency block coding is constituted is to carrying out the CDD operation.

4. according to the described space-time frequency coding method of claim 1, it is characterized in that described CDD coding further comprises: the right symbol of Alamouti coding is carried out the CDD operation, and the symbol that carries out after CDD operates sends on two antenna ports.

5. according to the described space-time frequency coding method of claim 1, it is characterized in that, described FSTD handles and specifically comprises: the Alamouti coding that does not carry out the CDD operation is handled carrying out FSTD, be that different Alamouti encodes to sending on different antenna ports, same Alamouti coding is to sending on identical antenna port; Symbol through the CDD encoding process does not carry out the FSTD processing.

6. according to the described space-time frequency coding method of claim 1, it is characterized in that described different Alamouti coding is to sending being spaced apart on 4 the different antennae port.

7. a space-time frequency coding device is characterized in that, comprising:

First coding module is used for symbol to be sent on the transmitting antenna is carried out space frequency block coding;

Second coding module is used for circulate delay diversity CDD coding of the symbol behind the space frequency block coding;

The FSTD processing module is used for obtaining the space-time frequency coding matrix to handling for the symbol that carries out described CDD coding carries out FSTD.

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