Method and apparatus for estimating a channel quality indicator (CQI) for multiple input multiple output (MIMO) systems

• US 8,644,262 B1
• Filed: 05/20/2011
• Issued: 02/04/2014
• Est. Priority Date: 05/20/2010
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Marvell International Limited (Marvell Technology Group Limited)
• Inventors: Sun, Yakun, Matache, Adina, Lee, Jungwon
• Primary Examiner(s): Chery, Dady
• Application Number:
  US13/112,009
• Time in Patent Office: 991 Days
• Field of Search: 370/252, 370/229, 370/333, 370/329, 370/465, 370/481, 375/260, 375/267, 375/227, 375/299, 455/69, 455/101
• US Class Current: 370/333
• CPC Class Codes: H04B 17/336 Signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR]
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0456 Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
• CPC Class Codes: H04B 7/0632 Channel quality parameters, e.g. channel quality indicator [CQI]
• CPC Class Codes: H04B 7/066 Combined feedback for a number of channels, e.g. over several subcarriers like in orthogonal frequency division multiplexing [OFDM]
• CPC Class Codes: H04B 7/0671 using different delays between antennas
• CPC Class Codes: H04B 7/0673 using feedback from receiving side
• CPC Class Codes: H04B 7/0678 using different spreading codes between antennas code allocation H04J13/16
• CPC Class Codes: H04B 7/068 using space frequency diversity space-frequency coding H04L1/0606
• CPC Class Codes: H04B 7/0691 using subgroups of transmit antennas
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/0029 Reduction of the amount of signalling, e.g. retention of useful signalling or differential signalling power control H04W52/04
• CPC Class Codes: H04L 1/0036 arrangements specific to the receiver
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 5/0023 Time-frequency-space

Abstract

Systems and methods are provided for determining a channel quality indicator (CQI) in a transmission system associated with a diversity transmission scheme. A plurality of independent diversity branches are identified in the diversity transmission scheme. Each one of the independent diversity branches may correspond to a different portion of the effective channel and may include any suitable combination of frequency, time, and/or spatial components of the effective channel or of any wired or wireless paths or combinations of the same. An effective Signal-to-Noise Ratio (SNR) value is computed for each one of the identified independent diversity branches. The computed effective SNR values are combined for the identified independent diversity branches to generate a CQI value.

Claims

1. A method for determining a channel quality indicator (CQI) in a transmission system associated with an effective channel and a diversity transmission scheme, the method comprising:

identifying a plurality of independent diversity branches in the diversity transmission scheme, wherein each one of the independent diversity branches corresponds to a different portion of the effective channel;

computing, using receiver circuitry, a plurality of effective Signal-to-Noise Ratio (SNR) values, wherein each effective value corresponds to a respective one of the identified independent diversity branches; and

combining, using the receiver circuitry, the computed effective SNR values for the identified independent diversity branches to generate a CQI value.

2. The method for determining the CQI of claim 1, further comprising:

computing a plurality of Signal-to-Interference and Noise Ratio (SINR) values for each one of the independent diversity branches, wherein each SINR value is associated with a respective transmission instance received at the receiver circuitry; and

computing the effective SNR value for each one of the independent diversity branches based on the computed SINR values.

3. The method for determining the CQI of claim 2, further comprising:

averaging the effective SNR values over the independent diversity branches to compute a global effective SNR; and

mapping the global effective SNR to the CQI value.

4. The method for determining the CQI of claim 1, wherein each one of the independent diversity branches comprises one of a codeword and a stream transmitted in the transmission system.

5. The method for determining the CQI of claim 1, wherein each one of the independent diversity branches comprises a combination of (i) a precoding matrix W and (ii) a per-stream phase matrix U, wherein the precoding matrix W is associated with a respective tone received at the receiver circuitry.

6. The method for determining the CQI of claim 5, wherein each one of the independent diversity branches further comprises a cyclic delay matrix D, wherein the precoding cyclic delay matrix D is associated with the respective tone received at the receiver circuitry.

7. The method for determining the CQI of claim 6, further comprising:

identifying a plurality of combinations of (i) a precoding matrix W_l selected from a plurality of L precoding matrices, (ii) a cyclic delay phase k selected from a plurality of K delay phases, and (iii) a transmitted stream s selected from a plurality of S transmitted streams;

for each tone i received at the receiver circuitry, computing a plurality of SINR_is^(l,k) values, wherein each one of the SINR_is^(l,k) values corresponds to one of the identified combinations;

computing an effective SNR_eff,s^(l,k) value for each one of the identified combinations; and

averaging the computed SNR_eff,s^(l,k) values over the identified combinations to generate a global effective SNR.

8. The method for determining the CQI of claim 1, wherein each one of the independent diversity branches comprises a pair of transmit antennas and wherein the pair of transmit antennas are configured to transmit orthogonal vectors.

9. The method for determining the CQI of claim 8, further comprising:

for each transmission instance i received at the receiver circuitry, computing a plurality of SINR_i^(l) values associated with each one of the pairs of transmit antennas;

computing an effective SNR_eff^(l) value for each one of the pairs of transmit antennas; and

averaging the computed SNR_eff^(l) values over the pairs of transmit antennas to generate a global effective SNR.

10. The method for determining the CQI of claim 1, wherein the diversity transmission scheme is one of cyclic delay diversity (CDD), space-frequency block coding (SFBC), space-time block coding (STBC), and SFBC/STBC with antenna selection.

11. The method for determining the CQI of claim 1, wherein each diversity branch comprises at least one component of the effective channel, wherein the plurality of diversity branches includes less than all components of the effective channel.

12. A receiver for determining a channel quality indicator (CQI) in a transmission system associated with an effective channel and a diversity transmission scheme, the receiver comprising processing circuitry configured to:

identify a plurality of independent diversity branches in the diversity transmission scheme, wherein each one of the independent diversity branches corresponds to a different portion of the effective channel;

compute, using processing circuitry, a plurality of effective Signal-to-Noise Ratio (SNR) values, wherein each effective value corresponds to a respective one of the identified independent diversity branches; and

combine, using the processing circuitry, the computed effective SNR values for the identified independent diversity branches to generate a CQI value.

13. The receiver of claim 12, wherein the processing circuitry is further configured to:

compute a plurality of Signal-to-Interference and Noise Ratio (SINR) values for each one of the independent diversity branches, wherein each SINR value is associated with a respective transmission instance received at the receiver; and

compute the effective SNR value for each one of the independent diversity branches based on the computed SINR values.

14. The receiver of claim 13, wherein the processing circuitry is further configured to:

average the effective SNR values over the independent diversity branches to compute a global effective SNR; and

map the global effective SNR to the CQI value.

15. The receiver of claim 12, wherein

each one of the independent diversity branches comprises one of a codeword and a stream transmitted in the transmission system.

16. The receiver of claim 12, wherein

each one of the independent diversity branches comprises a combination of (i) a precoding matrix W and (ii) a per-stream phase matrix U, wherein the precoding matrix W is associated with a respective tone received at the receiver.

17. The receiver of claim 16, wherein

each one of the independent diversity branches further comprises a cyclic delay matrix D, wherein the precoding cyclic delay matrix D is associated with the respective tone received at the receiver.

18. The receiver of claim 17, wherein the processing circuitry is further configured to:

identify a plurality of combinations of (i) a precoding matrix W_l selected from a plurality of L precoding matrices, (ii) a cyclic delay phase k selected from a plurality of K delay phases, and (iii) a transmitted stream s selected from a plurality of S transmitted streams;

for each tone i received at the receiver circuitry, compute a plurality of SINR_is^(l,k) values, wherein each one of the SINR_is^(l,k) values corresponds to one of the identified combinations;

compute an effective SNR_eff,s^(l,k) value for each one of the identified combinations; and

average the computed SNR_eff,s^(l,k) values over the identified combinations to generate a global effective SNR.

19. The receiver of claim 12, wherein

each one of the independent diversity branches comprises a pair of transmit antennas and wherein the pair of transmit antennas are configured to transmit orthogonal vectors.

20. The receiver of claim 19, wherein the processing circuitry is further configured to:

for each transmission instance i received at a receiver of the transmission system, compute a plurality of SNR_eff,s^(l,k) values associated with each one of the pairs of transmit antennas;

compute an effective SNR_eff,s^(l) value for each one of the pairs of transmit antennas; and

average the computed SNR_eff^(l) values over the pairs of transmit antennas to generate a global effective SNR.

21. The receiver of claim 12, wherein the diversity transmission scheme is one of cyclic delay diversity (CDD), space-time block coding (STBC), and SFBC/STBC with antenna selection.