Linear space-time block code with block STTD structure

• US 20030147343A1
• Filed: 11/21/2002
• Published: 08/07/2003
• Est. Priority Date: 11/21/2001
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Onggosanusi, Eko N., Dabak, Anand G.
• Granted Patent: US 7,301,893 B2
• Time in Patent Office: Days
• US Class Current: 370/209
• CPC Class Codes: H04B 1/7115 Constructive combining of multi-path signals, i.e. RAKE receivers
• CPC Class Codes: H04L 1/0618 Space-time coding

Abstract

Space-time block code with structure of a block STTD. 2×2 blocks allow partial orthogonality for low-complexity detection and optimized diversity gain and coding gain.

Claims

1. A method of space-time block code design, comprising;

(a) for an integer N greater than 1, defining 2N×

2N code matrices of the form

$C<br><br>\left(s\right)=\left[\begin{array}{cc}{C}_{\mathrm{\alpha <br><br>}}& C_{\mathrm{\beta <br><br>}}\\ -C_{\mathrm{\beta <br><br>}}^{*}& C_{\mathrm{\alpha <br><br>}}^{*}\end{array}\right]$

with N×

N submatrices;

C_α

=Σ

<sub>1≦

m≦

N</sub> s_m A_m+s_m*B_mC_β

=Σ

<sub>N+1≦

m≦

2N</sub> s_m A_m+s_m*B_m

where each of A_m and B_m is a N×

N complex matrix and s₁, s₂, . . . , s<sub>2N−

1</sub>, s_2N is a block of symbols.

2. The method of claim 1, wherein:

(a) N=2.

3. The method of claim 2, wherein:

(a) said B₁=B₂=B₃=B₄=0; and

(b) det[a_j1 a_kl]+det[a_j2 a_k2]=0 for j in the set {1,2} and k in the set {3,4} where a_j1 is the first column of A_j, a_k1 is the first column of A_k, a_j2 is the second column of A_j, and a_k2 is the second column of A_k.

4. The method of claim 3, wherein:

(a) said defining of step (a) of claim 1 includes searching over possible A₁, A₂, A₃, A₄, with a diversity gain of 4 to maximize coding gain.

5. The method of claim 3, wherein:

(a) said defining of step (a) of claim 1 includes (i) searching over possible A₁, A₂, A₃, A₄, with a diversity gain of 4 and a maximum coding gain; and

then (ii) searching over possible A₁, A₂, A₃, A₄, with a diversity gain of 4 and a coding gain exceeding a threshold determined as a fraction of said maximum coding gain from substep (i) to minimize code multiplicity.

6. The method of claim 3, wherein:

(a) A₃=A₁* and A₄=A₂*; and

(b) A₁, A₂, are selected from the group consisting of pairs of 2×

2 diagonal matrices and right multiplications of such pairs by a 2×

2 orthogonal matrix, wherein A₁ is not a multiple of A₂.

7. The method of claim 3, wherein:

(a) A₃=A₁* and A₄=A₂*; and

(b) A₁, A₂, are selected from the group consisting of pairs of 2×

2 diagonal matrices

$\left[\begin{array}{cc}{\mathrm{\theta <br><br>}}_{11}& 0\\ 0& {\mathrm{\theta <br><br>}}_{21}\end{array}\right],\left[\begin{array}{cc}{\mathrm{\theta <br><br>}}_{12}& 0\\ 0& {\mathrm{\theta <br><br>}}_{22}\end{array}\right],$

where the matrix

$\mathrm{\Theta <br><br>}=\left[\begin{array}{cc}{\mathrm{\theta <br><br>}}_{11}& {\mathrm{\theta <br><br>}}_{12}\\ {\mathrm{\theta <br><br>}}_{21}& {\mathrm{\theta <br><br>}}_{22}\end{array}\right]$

is a unitary matrix, and right multiplications of such pairs by a 2×

2 orthogonal matrix,

8. A method of transmission, comprising;

(a) space-time block encoding a symbol stream; and

(b) transmitting the results from step (a) from a plurality of antennas;

(c) wherein said space-time block code has 4×

4 code matrices of the form

$C<br><br>\left(s\right)=\left[\begin{array}{cc}{c}_{\mathrm{\alpha <br><br>}}& C_{\mathrm{\beta <br><br>}}\\ -C_{\mathrm{\beta <br><br>}}^{*}& C_{\mathrm{\alpha <br><br>}}^{*}\end{array}\right]$

with 2×

2 submatrices;

C_α

=s₁ A₁+s₂ A₂+s₁*B₁+s₂*B₂C_β

=s₃ A₃+s₄ A₄+s₃*B₃+s₄*B₄

where each of A_k and B_k is a 2×

2 complex matrix and s₁, s₂, s₃, s₄ is a block of symbols of said symbol stream.

9. The method of claim 8, wherein:

(a) said B₁=B₂=B₃=B₄=0; and

(b) det[a_j1 a_k1]+det[a_j2 a_k2]=0 for j in the set {1,2} and k in the set {3,4} where a_j1 is the first column of A_j, a_k1 is the first column of A_k, a_j2 is the second column of A_j, and a_k2 is the second column of A_k.

10. The method of claim 8, wherein:

(a) said transmitting of step (b) of claim 8 is TDMA.

11. The method of claim 8, wherein:

(a) said transmitting of step (b) of claim 8 is CDMA.

12. The method of claim 8, wherein:

(a) said transmitting of step (b) of claim 8 is OFDM.

13. A method of reception, comprising;

(a) receiving signals of space-time block encoded symbol stream from a plurality of antennas; and

(b) detecting said received signals including partitioning blocks of four received symbols for detection in two parallel 2×

2 detectors;

(c) wherein said space-time block code has 4×

4 code matrices of the form

$C<br><br>\left(s\right)=\left[\begin{array}{cc}{c}_{\mathrm{\alpha <br><br>}}& C_{\mathrm{\beta <br><br>}}\\ -C_{\mathrm{\beta <br><br>}}^{*}& C_{\mathrm{\alpha <br><br>}}^{*}\end{array}\right]$

with 2×

2 submatrices;

C_α

=s_i A₁+s₂ A₂+s₁*B₁+s₂*B₂C_β

=s₃ A₃+S₄ A₄+s₃*B₃+s₄*B₄

where each of A_k and B_k is a 2×

2 complex matrix and s₁, s₂, s₃, s₄ is a block of symbols of said symbol stream.

14. The method of claim 13, wherein:

(a) said B₁=B₂=B₃=B₄=0; and

(b) det[a_j1 a_k1]+det[a_j2 a_k2]=0 for j in the set {1,2} and k in the set {3,4} where a_j1 is the first column of A_j, a_k1 is the first column of A_k, a_j2 is the second column of A_j, and a_k2 is the second column of A_k.

15. The method of claim 13, wherein:

(a) said receiving of step (a) of claim 13 is TDMA.

16. The method of claim 13, wherein:

(a) said receiving of step (a) of claim 13 is CDMA.

17. The method of claim 13, wherein:

(a) said receiving of step (a) of claim 13 is OFDM.