Method and apparatus for channel estimation with transmit diversity

• US 6,853,689 B1
• Filed: 05/19/2000
• Issued: 02/08/2005
• Est. Priority Date: 07/15/1999
• Status: Expired due to Term

• Current Assignee: Optis Wireless Technology, LLC (Brevet Capital)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Nilsson, Johan
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): WILLIAMS, LAWRENCE B
• Application Number:
  US09/573,157
• Time in Patent Office: 1,726 Days
• Field of Search: 375/267, 375/347, 375/349
• US Class Current: 375/267
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04L 1/0618 Space-time coding
• CPC Class Codes: H04L 25/0204 of multiple channels

Abstract

A method and apparatus are described for estimating channels in a radio communication system using transmit diversity. Channel coefficients ĝ₁₁,ĝ₁₂,ĝ₂₁,ĝ₂₂ associated with a transmit diversity channel may be estimated in a radio communication system having a Base Station (BS) and at least one Mobile Station (MS) includes a transmit diversity channel transmitted over at least two propagation paths from at least two antennas associated with a BS. A sequence of pilot symbols is provided for each of at least two antennas for transmission from the BS to a MS over the transmit diversity channel. A series of symbols r₁, r₂, r₃, r₄ are received at the MS from the transmit diversity channel and a matrix P of values of the sequence of pilot symbols is established according to a relation which satisfies a full rank condition for the matrix P which may be stored together with P⁻¹ in a memory. Channels estimates are determined using the matrix and the received sequence.

Claims

1. A method for estimating channel coefficients ĝ

₁₁,ĝ

₁₂,ĝ

₂₁,ĝ

₂₂, associated with a transmit diversity channel in a radio communication system having a Base Station (BS) and at least one Mobile Station (MS), said transmit diversity channel being transmitted over at least two propagation paths from at least two antennas associated with said BS, said method comprising the steps of;

providing a sequence of pilot symbols for each of said at least two antennas for transmission from said BS to said MS over said transmit diversity channel;

receiving a series of symbols r₁, r₂, r₃, r₄ at said MS from said transmit diversity channel;

establishing a matrix of values of said sequence of pilot symbols

wherein said sequence of pilot symbols is selected such that said matrix has full rank; and

determining said channel coefficients ĝ

₁₁,ĝ

₁₂,ĝ

₂₁,ĝ

₂₂, using said matrix and said series of symbols r₁, r₂, r₃, r₄.

2. The method of claim 1, wherein said step of establishing further includes a step of retrieving said matrix from a memory.

3. The method of claim 1, wherein said sequence of pilot symbols further includes a first sequence p₁, p₂, p₃, and p₄ associated with a first one of said at least two antennas and a second sequence p₁, −

p*₄, −

p₃, and p*₂ associated with a second one of said at least two antennas.

4. The method of claim 3, wherein said sequence further includes p₁=−

1−

j, p₂=−

1−

j, p₃=−

1−

j, and p₄=−

1+j.

5. The method of claim 3, wherein said matrix comprises a matrix of the form $P=\left[\begin{array}{cccc}{p}_1& 0& p_1& 0\\ p_2& 0& -p_4^{*}& 0\\ 0& p_3& 0& -p_3\\ 0& p_4& 0& p_2^{*}\end{array}\right].$

21. The method of claim 1, wherein a matrix P⁻

1 is an inverse of the matrix of values of said sequence of pilot symbols, and wherein said channel coefficients ĝ

₁₁,ĝ

₁₂,ĝ

₂₁,ĝ

₂₂, are determined according to a relation $\left[\begin{array}{c}{\hat{g}}_{11}\\ {\hat{g}}_{12}\\ {\hat{g}}_{21}\\ {\hat{g}}_{22}\end{array}\right]=P^{-1}<br><br>\left[\begin{array}{c}{r}_1\\ r_2\\ r_3\\ r_4\end{array}\right].$

22. The method of claim 21, comprising retrieving the matrix P⁻

1 from a memory.

6. A method for estimating channel coefficients ĝ

₁₁,ĝ

₁₂,ĝ

₂₁,ĝ

₂₂, associated with a transmit diversity channel in a Mobile Station (MS), said transmit diversity channel being transmitted over at least two propagation paths from at least two antennas associated with a transmitter, said method comprising the steps of;

receiving a series of symbols r₁, r₂, r₃, r₄ at said MS from said transmit diversity channel;

establishing a matrix of values of a known sequence of pilot symbols

wherein said known sequence of pilot symbols are selected such that said matrix has full rank; and

determining said channel coefficients ĝ

₁₁,ĝ

₁₂,ĝ

₂₁,ĝ

₂₂, using said matrix and said series of symbols r₁, r₂, r₃, r₄.

7. The method of claim 6, wherein said step of establishing further includes the step of retrieving said matrix from a memory.

8. The method of claim 6, wherein said known sequence of pilot symbols further includes a first sequence p₁, p₂, p₃, and p₄ associated with a first one of said at least two antennas and a second sequence p₁, −

p*₄, −

p₃, and p*₂ associated with a second one of said at least two antennas.

9. The method of claim 8, wherein the known sequence further includes p₁=−

1−

j, p2=−

1−

j, p₃=−

1−

j, and p₄=−

1+j.

10. The method of claim 8, wherein said matrix comprises a matrix of the form $P=\left[\begin{array}{cccc}{p}_1& 0& p_1& 0\\ p_2& 0& -p_4^{*}& 0\\ 0& p_3& 0& -p_3\\ 0& p_4& 0& p_2^{*}\end{array}\right]$

23. The method of claim 6, wherein a matrix P⁻

1 is an inverse of the matrix of values of said sequence of pilot symbols, and wherein said channel coefficients ĝ

₁₁,ĝ

₁₂,ĝ

₂₁,ĝ

₂₂, are determined according to a relation $\left[\begin{array}{c}{\hat{g}}_{11}\\ {\hat{g}}_{12}\\ {\hat{g}}_{21}\\ {\hat{g}}_{22}\end{array}\right]=P^{-1}<br><br>\left[\begin{array}{c}{r}_1\\ r_2\\ r_3\\ r_4\end{array}\right].$

24. The method of claim 23, comprising retrieving the matrix P⁻

1 from a memory.

11. An apparatus for estimating channel coefficients ĝ

₁₁,ĝ

₁₂,ĝ

₂₁,ĝ

₂₂, associated with a transmit diversity channel in a radio communication system having Base Station (BS) and at least one Mobile Station (MS), said transmit diversity channel being transmitted over at least two propagation paths from at least two antennas associated with said BS, said apparatus comprising;

means for providing a sequence of pilot symbols for each of said at least two antennas for transmission from said BS to said MS over said transmit diversity channel;

means for receiving a series of symbols r₁, r₂, r₃, r₄ at said MS from said transmit diversity channel;

means for establishing a matrix of values of said sequence of pilot symbols

wherein said sequence of pilot symbols is selected such that said matrix has full rank; and

means for determining said channel coefficients ĝ

₁₁,ĝ

₁₂,ĝ

₂₁,ĝ

₂₂, using said matrix and said series of symbols r₁, r₂, r₃, r₄.

12. The apparatus of claim 11, wherein said means for establishing further includes storage means for storing said matrix.

13. The apparatus of claim 11, wherein said sequence of pilot symbols further includes a first sequence p₁, p₂, p₃, and p₄ associated with a first one of said at least two antennas and a second sequence p₁, −

p*₄, −

p₃, and p*₂ associated with a second one of said at least two antennas.

14. The apparatus of claim 13, wherein said sequence further includes p₁=−

1−

j, p₂=−

1−

j, p₃=−

1−

j, and p₄=−

1+j.

15. The apparatus of claim 13, wherein said matrix comprises a matrix of the form $P=\left[\begin{array}{cccc}{p}_1& 0& p_1& 0\\ p_2& 0& -p_4^{*}& 0\\ 0& p_3& 0& -p_3\\ 0& p_4& 0& p_2^{*}\end{array}\right].$

25. The apparatus of claim 11, wherein a matrix P⁻

1 is an inverse of the matrix of values of said sequence of pilot symbols, and wherein said means for determining determines said channel coefficients ĝ

₁₁,ĝ

₁₂,ĝ

₂₁,ĝ

₂₂, according to a relation $\left[\begin{array}{c}{\hat{g}}_{11}\\ {\hat{g}}_{12}\\ {\hat{g}}_{21}\\ {\hat{g}}_{22}\end{array}\right]=P^{-1}<br><br>\left[\begin{array}{c}{r}_1\\ r_2\\ r_3\\ r_4\end{array}\right].$

26. The apparatus of claim 25, wherein said means for establishing includes storage means for storing said matrix P⁻

1.

16. An Apparatus for estimating channel coefficients ĝ

₁₁,ĝ

₁₂,ĝ

₂₁,ĝ

₂₂, associated with a transmit diversity channel in a Mobile Station (MS), said transmit diversity channel being transmitted over at least two propagation paths from at least two antennas associated with a transmitter, said apparatus comprising;

means for receiving a series of symbols r₁, r₂, r₃, r₄ at said MS from said transmit diversity channel;

means for establishing a matrix of values of a known sequence of pilot symbols wherein said known sequence of pilot symbols is selected such that said matrix has full rank; and

means for determining said channel coefficients ĝ

₁₁,ĝ

₁₂,ĝ

₂₁,ĝ

₂₂, using said matrix and said series of symbols r₁, r₂, r₃, r₄.

17. The apparatus of claim 16, wherein said means for establishing further includes a storage means for storing said matrix.

18. The apparatus of claim 16, wherein said known sequence of pilot symbols further includes a first sequence p₁, p₂, p₃, and p₄ associated with a first one of said at least two antennas and a second sequence p₁, −

p*₄, −

p₃, and p*₂ associated with a second one of said at least two antennas.

19. The apparatus of claim 18, wherein said known sequence further includes p₁=−

1−

j, p₂=−

1−

j, p₃=−

1−

j, and p₄=−

1+j.

20. The apparatus of claim 18, wherein said matrix comprises a matrix of the form $P=\left[\begin{array}{cccc}{p}_1& 0& p_1& 0\\ p_2& 0& -p_4^{*}& 0\\ 0& p_3& 0& -p_3\\ 0& p_4& 0& p_2^{*}\end{array}\right].$

27. The apparatus of claim 16, wherein a matrix P⁻

1 is an inverse of the matrix of values of said sequence of pilot symbols, and wherein said means for determining determines said channel coefficients ĝ

₁₁,ĝ

₁₂,ĝ

₂₁,ĝ

₂₂, according to a relation $\left[\begin{array}{c}{\hat{g}}_{11}\\ {\hat{g}}_{12}\\ {\hat{g}}_{21}\\ {\hat{g}}_{22}\end{array}\right]=P^{-1}<br><br>\left[\begin{array}{c}{r}_1\\ r_2\\ r_3\\ r_4\end{array}\right].$

28. The apparatus of claim 27, wherein said means for establishing includes storage means for storing said matrix P⁻

1.