Apparatus and method for transmitting data using full-diversity, full-rate STBC

• US 20060056538A1
• Filed: 08/17/2005
• Published: 03/16/2006
• Est. Priority Date: 08/17/2004
• Status: Abandoned Application

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Nam, Seung-Hoon, Hwang, Chan-Soo, Chung, Jae-Hak, Chae, Chan-Byoung, Jung, Young-Ho, Roh, Won-Il
• Application Number:
  US11/205,931
• Publication Number:
  US 20060056538A1
• Time in Patent Office: Days
• US Class Current: 375/298
• CPC Class Codes: H04B 7/0613 using simultaneous transmission H04B7/0686 takes precedence
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04L 1/0643 block codes
• CPC Class Codes: H04L 27/34 Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems

Abstract

A data transmission apparatus and method using a full-diversity, full-rate STBC are provided. In the data transmission apparatus, a serial-to-parallel converter converts an input bit stream to parallel binary vectors. A bit/symbol mapper generates modulator input symbols by combining the bits of the binary vectors. A modulator modulates the modulator input symbols to complex symbols. A transmit matrix block encoder encodes the complex symbols using a transmit matrix and transmits the coded symbols through corresponding transmit antennas.

Claims

1. A transmitter comprising:

a serial-to-parallel converter for converting an input bit stream to parallel binary vectors;

a bit/symbol mapper for generating modulator input symbols by combining the bits of the binary vectors;

a modulator for modulating the modulator input symbols to complex symbols; and

a transmit matrix block encoder for encoding the complex symbols using a transmit matrix and transmitting the coded symbols through corresponding transmit antennas.

2. The transmitter of claim 1, wherein each of the modulator input symbols is a combination of bits extracted from different binary vectors for an identical time interval.

3. The transmitter of claim 1, wherein the modulator includes as many modulation modules as the number of the transmit antennas.

4. The transmitter of claim 3, wherein each of the modulation modules is a

$2^{\frac{N_{\mathrm{Tx}}}{}}$

B 2

quadrature amplitude modulation (QAM) modulation module, where B is the number of bits in every binary vector and N_Tx is the number of the transmit antennas.

5. The transmitter of claim 3, wherein each of the modulation modules has a signal constellation having irregular distances between signal points to which modulator input symbols are mapped.

6. The transmitter of claim 3, wherein each of the modulation modules divides the bits of a modulator input symbol into two groups, and maps a first group to an output value on a real number axis in the signal constellation and a second group to an output value on an imaginary number axis in the signal constellation.

7. The transmitter of claim 6, wherein the first group includes upper bits being a first half of the modulator input symbol and the second group includes lower bits being a second half of the modulator input symbol.

8. A signal transmission method comprising the steps of:

generating modulator input symbols by combining bits of parallel binary vectors;

modulating the modulator input symbols to complex symbols in a predetermined modulation scheme; and

encoding the complex symbols using a transmit matrix and transmitting the coded symbols through corresponding transmit antennas.

9. The signal transmission method of claim 8, wherein the generating step comprises generating each of the modulator input symbols by combining bits extracted from different binary vectors for an identical time interval.

10. The signal transmission method of claim 8, wherein the modulation scheme is

$2^{\frac{N_{\mathrm{Tx}}}{}}$

B 2

quadrature amplitude modulation (QAM) where B is the number of bits in every binary vector and N_Tx is the number of the transmit antennas.

11. The signal transmission method of claim 10, wherein the modulation scheme has a signal constellation having irregular distances between signal points to which modulator input symbols are mapped.

12. The signal transmission method of claim 11, wherein the modulating step comprises dividing the bits of each modulator input symbol into two groups and mapping a first group to an output value on a real number axis in the signal constellation and a second group to an output value on an imaginary number axis in the signal constellation.

13. The signal transmission method of claim 12, wherein the first group includes upper bits being a first half of the modulator input symbol and the second group includes lower bits being a second half of the modulator input symbol.

14. A decoding method in a communication system having a transmitter for converting an input bit stream to parallel binary vectors, generating modulator input symbols by combining the bits of the binary vectors, modulating the modulator input symbols to complex symbols in a predetermined modulation/demodulation scheme, encoding the complex symbols using a transmit matrix, and transmitting the coded symbols through corresponding transmit antennas, and a receiver for receiving signals from the transmit antennas on a radio channel, the method comprising the steps of:

estimating transmission symbols from the received signals;

obtaining complex symbols from the estimated transmission symbols;

obtaining modulator input symbols by demodulating the complex symbols using the same modulation/demodulation scheme as used in the transmitter;

obtaining binary vectors by demapping the modulator input symbols; and

recovering a transmission bit stream by demultiplexing the binary vectors.

15. The decoding method of claim 14, wherein the transmission symbols estimation step comprises estimating the transmission symbols using a maximum log likelihood (MLL) method.

16. The decoding method of claim 15, wherein the received signals are expressed as:

$\left[\begin{array}{c}{y}_1\\ y_2\\ y_3\\ y_4\end{array}\right]=\left[\begin{array}{cccc}{x}_1& x_2& 0& 0\\ x_2^{*}& -x_1^{*}& 0& 0\\ 0& 0& x_3& x_4\\ 0& 0& x_4^{*}& x_3^{*}\end{array}\right]<br><br>\left[\begin{array}{c}{h}_1\\ h_2\\ h_3\\ h_4\end{array}\right]+N$

where y_i denotes a signal received at an i^th symbol time and h_j denotes the channel response between a j^th transmit antenna and the receive antenna;

transmission symbol x_i is estimated by;

$\left(\begin{array}{c}{\hat{x}}_1\\ {\hat{x}}_2\\ {\hat{x}}_3\\ {\hat{x}}_4\end{array}\right)=\left(\begin{array}{cccc}{\mathrm{\alpha <br><br>}}^{-1}& 0& 0& 0\\ 0& {\mathrm{\alpha <br><br>}}^{-1}& 0& 0\\ 0& 0& {\mathrm{\beta <br><br>}}^{-1}& 0\\ 0& 0& 0& {\mathrm{\beta <br><br>}}^{-1}\end{array}\right)<br><br>\left(\begin{array}{cccc}{h}_1& h_2& 0& 0\\ -h_2^{*}& h_1^{*}& 0& 0\\ 0& 0& h_3& h_4\\ 0& 0& -h_4^{*}& -h_3^{*}\end{array}\right)<br><br>\left(\begin{array}{c}{y}_1\\ y_2^{*}\\ y_3\\ y_4^{*}\end{array}\right)$

where α

=|h₁|²+|h₂|² and β

=|h₃|²+|h₄|²; and

wherein an LLR of a b^th bit in transmission symbol x₁, LLRx_1b is computed by;

$\begin{array}{c}{\mathrm{LLR}}_{x_{1<br><br>b}}=<br><br>\log <br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{P<br><br>\left(x_{1<br><br>b}=1|y_1^1,y_1^2\right)}{P<br><br>\left(x_{1<br><br>b}=0|y_1^1,y_1^2\right)}\\ =<br><br>\log <br><br>\frac{\underset{{\widehat{\stackrel{\_}{s}}}_1\in <br><br>S_1^b<br><br>\left(1\right),{\widehat{\stackrel{\_}{s}}}_3,=f<br><br>\left({\widehat{\stackrel{\_}{s}}}_1\right)}{\sum <br><br>}<br><br>P<br><br>\left(y_1^1,y_1^2|{\widehat{\stackrel{\_}{s}}}_1\right)<br><br>P<br><br>\left({\widehat{\stackrel{\_}{s}}}_1\right)}{\underset{{\widehat{\stackrel{\_}{s}}}_1\in <br><br>S_1^b<br><br>\left(0\right),{\widehat{\stackrel{\_}{s}}}_3,=f<br><br>\left({\widehat{\stackrel{\_}{s}}}_1\right)}{\sum <br><br>}<br><br>P<br><br>\left(y_1^1,y_1^2|{\widehat{\stackrel{\_}{s}}}_1\right)<br><br>P<br><br>\left({\widehat{\stackrel{\_}{s}}}_1\right)}\\ =<br><br>\log <br><br>\frac{\underset{{\widehat{\stackrel{\_}{s}}}_1\in <br><br>S_1^b<br><br>\left(1\right),{\widehat{\stackrel{\_}{s}}}_3,=f<br><br>\left({\widehat{\stackrel{\_}{s}}}_1\right)}{\sum <br><br>}<br><br>P<br><br>\left(y_1^1|{\widehat{\stackrel{\_}{s}}}_1\right)<br><br>P<br><br>\left(y_1^2|{\widehat{\stackrel{\_}{s}}}_3\right)}{\underset{{\widehat{\stackrel{\_}{s}}}_1\in <br><br>S_1^b<br><br>\left(0\right),{\widehat{\stackrel{\_}{s}}}_3,=f<br><br>\left({\widehat{\stackrel{\_}{s}}}_1\right)}{\sum <br><br>}<br><br>P<br><br>\left(y_1^1|{\widehat{\stackrel{\_}{s}}}_1\right)<br><br>P<br><br>\left(y_1^2|{\widehat{\stackrel{\_}{s}}}_3\right)}\\ \cong <br><br><br><br>\log <br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{{\max }_{{\widehat{\stackrel{\_}{s}}}_1\in <br><br>S_1^b<br><br>\left(1\right),{\widehat{\stackrel{\_}{s}}}_3,=f<br><br>\left({\widehat{\stackrel{\_}{s}}}_1\right)}<br><br>P<br><br>\left(y_1^1|{\widehat{\stackrel{\_}{s}}}_1\right)<br><br>P<br><br>\left(y_1^2|{\widehat{\stackrel{\_}{s}}}_3\right)}{{\max }_{{\widehat{\stackrel{\_}{s}}}_1\in <br><br>S_1^b<br><br>\left(0\right),{\widehat{\stackrel{\_}{s}}}_3,=f<br><br>\left({\widehat{\stackrel{\_}{s}}}_1\right)}<br><br>P<br><br>\left(y_1^1|{\widehat{\stackrel{\_}{s}}}_1\right)<br><br>P<br><br>\left(y_1^2|{\widehat{\stackrel{\_}{s}}}_3\right)}\\ =<br><br>\underset{{\widehat{\stackrel{\_}{s}}}_1\in <br><br>S_1^b<br><br>\left(0\right),{\widehat{\stackrel{\_}{s}}}_3,=f<br><br>\left({\widehat{\stackrel{\_}{s}}}_1\right)}{\min }<br><br>\left(\frac{\mathrm{\alpha <br><br>}<br><br>{<br><br>z_1-{\widehat{\stackrel{\_}{s}}}_1<br><br>}^2+\mathrm{\beta <br><br>}<br><br>{<br><br>z_3-{\widehat{\stackrel{\_}{s}}}_3<br><br>}^2}{2<br><br>{\mathrm{\sigma <br><br>}}^2}\right)-\\ <br><br>\underset{{\widehat{\stackrel{\_}{s}}}_1\in <br><br>S_1^b<br><br>\left(1\right),{\widehat{\stackrel{\_}{s}}}_3,=f<br><br>\left({\widehat{\stackrel{\_}{s}}}_1\right)}{\min }<br><br>\left(\frac{\mathrm{\alpha <br><br>}<br><br>{<br><br>z_1-{\widehat{\stackrel{\_}{s}}}_1<br><br>}^2+\mathrm{\beta <br><br>}<br><br>{<br><br>z_3-{\widehat{\stackrel{\_}{s}}}_3<br><br>}^2}{2<br><br>{\mathrm{\sigma <br><br>}}^2}\right)\end{array}$

where x_1b is a b^th binary bit applied to a bit/symbol mapper to form the complex symbol x₁ and S₁^b(1) is a set of constellation points each having 1 as a b^th bit among candidate constellation points for the transmission symbol x₁, and {circumflex over ({overscore (s)})}₃=f({circumflex over ({overscore (s)})}₁) means that once {circumflex over ({overscore (s)})}₁ is decided, {circumflex over ({overscore (s)})}₃ is automatically determined by {circumflex over ({overscore (s)})}₁ because the binary bits of {circumflex over ({overscore (s)})}₁ have the same information as those of {circumflex over ({overscore (s)})}₃, but in a different order.