Interference cancellation of STBC with multiple streams in OFDM for wlan

• US 20050281361A1
• Filed: 10/08/2004
• Published: 12/22/2005
• Est. Priority Date: 06/16/2004
• Status: Abandoned Application

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Kim, Joonsuk
• Application Number:
  US10/960,571
• Publication Number:
  US 20050281361A1
• Time in Patent Office: Days
• US Class Current: 375/347
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04B 7/084 Equal gain combining, only phase adjustments antenna beam scanning or forming by phase or amplitude control H01Q3/26, e.g. phased arrays
• CPC Class Codes: H04B 7/0848 Joint weighting

Abstract

A method of receiving data over M receiving antennas from N streams from K*N transmitting antennas, where M, N and K are integers and M is greater than N, includes the steps of receiving N signals over the M receiving antennas, applying the N signals in pairs to a plurality of decoder modules, removing interference terms between the paired N signals and providing data in a plurality of channels, selecting weighting factors and applying the weighting factors to the plurality of channels and combining the weighted plurality of channels to derive received data.

Claims

1. A method of receiving data over M receiving antennas from N streams from K*N transmitting antennas, where M, N and K are integers and M is greater than N, the method comprising the steps of:

receiving N signals over the M receiving antennas;

applying the N signals in pairs to a plurality of decoder modules;

removing interference terms between the paired N signals and providing data in a plurality of channels;

selecting weighting factors and applying the weighting factors to the plurality of channels; and

combining the weighted plurality of channels to derive received data.

2. A method according to claim 1, wherein the step of receiving N signals over the M receiving antennas comprises receiving two signals over three receiving antennas.

3. A method according to claim 1, wherein the step of removing interference terms comprises zero-forcing terms equivalent to relationships between signals sent from the K*N transmitting antennas to the M receiving antennas to remove interference terms.

4. A method according to claim 3, wherein the relationships comprise:

r₁=H₁c₁+G₁c₂+n₁
r₂=H₂c₁+G₂c₂+n₂ where,
r₃=H₃c₁+G₃c₂+n₃$\begin{array}{ccc}{H}_i=\left[\begin{array}{cc}{h}_{1<br><br>i}& h_{2<br><br>i}\\ h_{2<br><br>i}^{*}& -h_{1<br><br>i}^{*}\end{array}\right],& \text{\hspace{1em}<br><br>}& G_i=\left[\begin{array}{cc}{h}_{3<br><br>i}& h_{4<br><br>i}\\ h_{4<br><br>i}^{*}& -h_{3<br><br>i}^{*}\end{array}\right],\end{array}$

and information from the plurality of channels comprises;

$\left[\begin{array}{c}{\tilde{r}}_i\\ {\tilde{r}}_j\end{array}\right]=\left[\begin{array}{cc}{\tilde{H}}_{\mathrm{ij}}& 0\\ 0& {\tilde{G}}_{\mathrm{ij}}\end{array}\right]<br><br>\left[\begin{array}{c}{c}_1\\ c_2\end{array}\right]+\left[\begin{array}{c}{\tilde{n}}_1\\ {\tilde{n}}_2\end{array}\right].$

5. A method according to claim 1, wherein the step of selecting weighting factors comprises selecting weighting factors of equal value.

6. A method according to claim 1, wherein the step of selecting weighting factors comprises selecting weighting factors proportional to relationships between signals sent from the K*N transmitting antennas to the M receiving antennas.

7. A method according to claim 6, wherein the step of selecting weighting factors comprises selecting weighting factors proportional to relationships between signals sent from the K*N transmitting antennas to the M receiving antennas divided noise values for those relationships.

8. A method according to claim 1, further comprising determining initial values of the received data and iterating values for the received data recursively until estimations of the received data are stabilized.

9. A receiver for receiving data over M receiving antennas transmitted from N streams from K*N transmitting antennas, where M, N and K are integers and M is greater than N, comprising:

receiving means for receiving N signals over the M receiving antennas;

applying means for applying the N signals in pairs to a plurality of decoder modules;

removing means for removing interference terms between the paired N signals and providing data in a plurality of channels;

weighting means for selecting weighting factors and applying the weighting factors to the plurality of channels; and

combining means combining the weighted plurality of channels to derive received data.

10. A receiver according to claim 9, wherein the removing means comprises zero-forcing means for zero-forcing terms equivalent to relationships between signals sent from the K*N transmitting antennas to the M receiving antennas to remove interference terms.

11. A receiver according to claim 10, wherein the relationships comprise:

r₁=H₁c₁+G₁c₂+n₁
r₂=H₂c₁+G₂c₂+n₂ where,
r₃=H₃c₁+G₃c₂+n₃$\begin{array}{ccc}{H}_i=\left[\begin{array}{cc}{h}_{1<br><br>i}& h_{2<br><br>i}\\ h_{2<br><br>i}^{*}& -h_{1<br><br>i}^{*}\end{array}\right],& \text{\hspace{1em}<br><br>}& G_i=\left[\begin{array}{cc}{h}_{3<br><br>i}& h_{4<br><br>i}\\ h_{4<br><br>i}^{*}& -h_{3<br><br>i}^{*}\end{array}\right],\end{array}$

and information from the plurality of channels comprises;

$\left[\begin{array}{c}{\tilde{r}}_i\\ {\tilde{r}}_j\end{array}\right]=\left[\begin{array}{cc}{\tilde{H}}_{\mathrm{ij}}& 0\\ 0& {\tilde{G}}_{\mathrm{ij}}\end{array}\right]<br><br>\left[\begin{array}{c}{c}_1\\ c_2\end{array}\right]+\left[\begin{array}{c}{\tilde{n}}_1\\ {\tilde{n}}_2\end{array}\right].$

12. A receiver according to claim 9, wherein the weighting means comprises means for selecting weighting factors of equal value.

13. A receiver according to claim 9, wherein the weighting means comprises means for selecting weighting factors proportional to relationships between signals sent from the K*N transmitting antennas to the M receiving antennas.

14. A receiver according to claim 13, wherein the weighting means comprises means for selecting weighting factors proportional to relationships between signals sent from the K*N transmitting antennas to the M receiving antennas divided noise values for those relationships.

15. A receiver according to claim 9, further comprising determining means for determining initial values of the received data and iterating means for iterating values for the received data recursively until estimations of the received data are stabilized.

16. A receiver for receiving data over M receiving antennas from N streams transmitted by K*N transmitting antennas, where M, N and K are integers and M is greater than N, the receiver comprising:

M receiving antennas, configured to receive N signals;

a plurality of decoder modules, configured to receive the N signals in pairs, to remove interference terms between the paired N signals and to provide data in a plurality of channels;

weighting units, configured to select weighting factors and to apply the weighting factors to the plurality of channels; and

at least one mixer, configured to combine the weighted plurality of channels to derive received data.

17. A receiver according to claim 16, wherein the plurality of decoder modules are configured to remove interference terms through zero-forcing terms equivalent to relationships between signals sent from the K*N transmitting antennas to the M receiving antennas to remove interference terms.

18. A receiver according to claim 17, wherein the relationships comprise:

r₁=H₁c₁+G₁c₂+n₁
r₂=H₂c₁+G₂c₂+n₂ where,
r₃=H₃c₁+G₃c₂+n₃$H_i=\left[\begin{array}{cc}{h}_{1<br><br>i}& h_{2<br><br>i}\\ h_{2<br><br>i}^{*}& -h_{1<br><br>i}^{*}\end{array}\right],G_i=\left[\begin{array}{cc}{h}_{3<br><br>i}& h_{4<br><br>i}\\ h_{4<br><br>i}^{*}& -h_{3<br><br>i}^{*}\end{array}\right],$

and information from the plurality of channels comprises;

$\left[\begin{array}{c}{\tilde{r}}_i\\ {\tilde{r}}_j\end{array}\right]=\left[\begin{array}{cc}{\tilde{H}}_{\mathrm{ij}}& 0\\ 0& {\tilde{G}}_{\mathrm{ij}}\end{array}\right]<br><br>\left[\begin{array}{c}{c}_1\\ c_2\end{array}\right]+\left[\begin{array}{c}{\tilde{n}}_1\\ {\tilde{n}}_2\end{array}\right].$

19. A receiver according to claim 16, wherein the weighting units are configured to select weighting factors of equal value.

20. A receiver according to claim 16, wherein the weighting units are configured to select weighting factors proportional to relationships between signals sent from the K*N transmitting antennas to the M receiving antennas.

21. A receiver according to claim 20, wherein the weighting units are configured to select weighting factors proportional to relationships between signals sent from the K*N transmitting antennas to the M receiving antennas divided noise values for those relationships.

22. A receiver according to claim 16, wherein the plurality of decoder modules are configured to determine initial values of the received data and iterate values for the received data recursively until estimations of the received data are stabilized.