PRECODING FOR SINGLE TRANSMISSION STREAMS IN MULTIPLE ANTENNA SYSTEMS

• US 20150271003A1
• Filed: 06/09/2015
• Published: 09/24/2015
• Est. Priority Date: 06/18/2008
• Status: Active Grant

• Current Assignee: Centre of Excellence in Wireless Technology
• Original Assignee: Centre of Excellence in Wireless Technology
• Inventors: Kuchi, Kiran Kumar, Jeniston, Deviraj Klutto Milleth, Ramaswamy, Vinod, Dhivagar, Baskaran, Giridhar, Krishnamurthi, Ramamurthi, Bhaskar, Kalathil, Dileep Manisseri, Suryasarman, Padmanabhan Madampu
• Granted Patent: US 9,225,575 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04B 7/0456 Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04B 7/0632 Channel quality parameters, e.g. channel quality indicator [CQI]
• CPC Class Codes: H04L 1/0656 Cyclotomic systems, e.g. Bell Labs Layered Space-Time [BLAST]
• CPC Class Codes: H04L 25/0224 using sounding signals
• CPC Class Codes: H04L 27/20 Modulator circuits; Transmitter circuits
• CPC Class Codes: H04L 27/261 Details of reference signals
• CPC Class Codes: H04L 27/2636 with FFT or DFT modulators, e.g. standard single-carrier frequency-division multiple access [SC-FDMA] transmitter or DFT spread orthogonal frequency division multiplexing [DFT-SOFDM]
• CPC Class Codes: H04L 27/2646 using feedback from receiver for adjusting OFDM transmission parameters, e.g. transmission timing or guard interval length
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 27/26526 with inverse FFT [IFFT] or inverse DFT [IDFT] demodulators, e.g. standard single-carrier frequency-division multiple access [SC-FDMA] receiver or DFT spread orthogonal frequency division multiplexing [DFT-SOFDM]
• CPC Class Codes: H04L 5/0023 Time-frequency-space

Abstract

Precoding for multiple transmission streams in multiple antenna systems. Disclosed herein is a general method that transmits signal from multiple antennas using a one/two dimensional precoder. This precoder is fixed in a given resource block (RB) or slot, which is composed of P subcarriers and Q OFDM symbols (where the values for P and Q are greater than or equal to 1). The precoder in each resource block may take same or different values, which span the two dimensional time-frequency grid. The precoder is chosen as a function of either logical frequency index or physical frequency index of the RB.

Claims

1. An OFDM receiver comprising of a baseband portion, where said OFDM receiver receives a precoded OFDM transmit signal comprising of precoded pilot tones and precoded data tones, further where said precoded OFDM transmit signal relies on at least one of time index of a subcarrier of said precoded OFDM transmit signal;

frequency index of said subcarrier; and

time and frequency indices of said subcarrier and is transmitted using a plurality of antennas, said baseband portion further comprising of at least one means adapted for;

estimating channel state information using said precoded pilot tones;

estimating interference covariance estimation using said precoded pilot tones;

demodulating said precoded data tones; and

computing filter weights using said channel state information and said interference covariance estimation.

2. The OFDM receiver as claimed in claim 1, wherein said receiver is configured to compute said filter weights using estimated channel and interference covariance.

3. The OFDM receiver as claimed in claim 1, wherein a filter module is configured to demodulate said precoded data tones and compute said filter weights.

4. The OFDM receiver as claimed in claim 1, wherein precoded OFDM transmit signal for N_t transmission antennas is obtained by transmitting elements of y simultaneously from said N_t antennas, where y=W(p,q)s_k,l, further wherein s_k,l denotes signal present in kth subcarrier and the lth OFDM symbol contained in the (p,q)th unit of single stream, p is frequency index of y, q is time index of y and W(p,q) is a N_t×

1 vector.

5. The OFDM receiver as claimed in claim 4, wherein said signal present in kth subcarrier is one of pilot and data.

6. The OFDM receiver as claimed in claim 4, wherein said unit of said stream comprises of P contiguous subcarriers and Q contiguous OFDM symbols.

7. The OFDM receiver as claimed in claim 4, wherein elements of said W(p,q) contains antenna specific phase rotation of the (p,q)th unit of said stream.

8. The OFDM receiver as claimed in claim 4, wherein said W(p,q) applied on each element in said stream is indicated by a predefined pattern.

9. The OFDM receiver as claimed in claim 4, wherein said elements of said stream comprises at least one of data and pilots.

10. A DFT-S-OFDMA receiver comprising of a baseband portion, where said receiver receives a precoded DFT-S-OFDMA transmit signal comprising of precoded pilot tones and precoded data tones, further where said precoded DFT-S-OFDMA transmit signal relies on at least one of time index of a subcarrier of said precoded DFT-S-OFDMA transmit signal;

frequency index of said subcarrier; and

time and frequency indices of said subcarrier and is transmitted using a plurality of antennas, said baseband portion further comprising of at least one means adapted for;

estimating channel state information using said precoded pilot tones;

estimating interference covariance estimation using said precoded pilot tones;

demodulating said precoded data tones; and

computing filter weights using said channel state information and said interference covariance estimation.

11. The DFT-S-OFDMA receiver as claimed in claim 10, wherein said receiver is configured to compute said filter weights using estimated channel and interference covariance.

12. The DFT-S-OFDMA receiver as claimed in claim 10, wherein a filter module is configured to demodulate said precoded data tones and compute said filter weights.

13. The DFT-S-OFDMA receiver as claimed in claim 10, wherein said receiver is configured to perform Inverse Digital Fourier Transform (IDFT) before demodulating said precoded data tones.

14. The DFT-S-OFDMA receiver as claimed in claim 10, wherein said precoded DFT-S-OFDMA transmit signal of pilot tones and data tones is obtained by at least one of:

1-Dimensional Phase Offset Diversity (1D-POD);

antenna switching in frequency; and

antenna switching in time;

wherein said precoded DFT-S-OFDMA transmit signal chosen from a plurality of signals using an antenna chosen from said plurality of antennas, wherein said antenna is specific to said signal and each of said plurality of signals is transmitted from a distinct antenna chosen from said plurality of antennas.

15. The DFT-S-OFDMA receiver as claimed in claim 10, wherein each of said subcarriers are transmitted using an identical precoder scheme.

16. The DFT-S-OFDMA receiver as claimed in claim 10, wherein said precoded DFT-S-OFDMA transmit signal is obtained by:

applying DFT precoding to an input stream of subcarriers, wherein said subcarriers comprise of Physical Resource Units (PRUs);

performing subcarrier mapping on said subcarriers;

performing IDFT on output of said subcarriers;

adding cyclic prefix to said subcarriers;

transmitting said subcarriers from a first antenna from said plurality of transmitting antennas;

transmitting said subcarriers multiplied with a PRU specific phase rotation from a second antenna from said plurality of transmitting antennas; and

transmitting said subcarriers multiplied with a phase rotation from subsequent antennas, wherein said phase rotation relies on PRU and specific antenna.

17. The DFT-S-OFDMA receiver as claimed in claim 16, wherein each of said subcarriers are transmitted using an identical precoder.

18. The DFT-S-OFDMA receiver as claimed in claim 10, wherein said precoded DFT-S-OFDMA transmit signal is obtained by:

applying DFT precoding to an input stream of subcarriers;

performing subcarrier mapping on said subcarriers;

multiplying each of said subcarriers with a plurality of complex weights, where said number of plurality of said complex weights is equal to number of said plurality of transmitting antennas;

performing IDFT on each of said subcarriers to create a plurality of signals; and

transmitting said plurality of signals from said plurality of antennas, wherein each signal is transmitted from a distinct antenna.

19. The DFT-S-OFDMA receiver as claimed in claim 18, wherein magnitude and phase of said complex weight depends on an antenna from said plurality of antennas, wherein said antenna is used to transmit a subcarrier from said plurality of subcarriers.

20. The DFT-S-OFDMA receiver as claimed in claim 18, wherein each of said subcarriers are transmitted using an identical precoder.

21. The DFT-S-OFDMA receiver as claimed in claim 10, wherein said precoded DFT-S-OFDMA transmit signal is obtained by:

modulating FEC encoded data;

splitting said modulating FEC encoded data into a plurality of data sets, where number of said plurality of data sets is equal to said number of said plurality of antennas;

modulating each of said plurality of data sets onto contiguous subcarriers;

encoding each of said plurality of data sets using a DFT-S-OFDMA transmitter; and

transmitting each of said plurality of data sets on distinct antennas chosen from said plurality of antennas.

22. The DFT-S-OFDMA receiver as claimed in claim 10, wherein said precoded DFT-S-OFDMA transmit signal is obtained by:

modulating FEC encoded data;

splitting said modulating FEC encoded data into a plurality of data sets, where number of said plurality of data sets is equal to said number of said plurality of antennas;

performing DFT operation on each of said data sets to create a set of DFT precoded data;

modulating each of said DFT precoded data onto contiguous subcarriers to create DFT precoded data sets;

precoding each of said plurality of DFT precoded data sets using a multi-antenna precoder for a subset of said plurality of antennas to create a plurality of multi-antenna DFT precoded data streams;

performing IDFT on each of said plurality of plurality of multi-antenna DFT precoded data streams to obtain multi-antenna precoded data streams;

mapping said multi-antenna precoded data streams to said plurality of antennas; and

transmitting each of said plurality of multi-antenna precoded data streams on distinct antennas chosen from said plurality of antennas.

23. The DFT-S-OFDMA receiver as claimed in claim 22, wherein mapping of said precoded data sets to said plurality of antennas varies with one of time and frequency.

24. A DFT-S-OFDMA system with precoding comprising of a plurality of transmitting antennas, said system comprising of:

means for estimating channel state information using said precoded pilot tones;

means for estimating interference covariance estimation using said precoded pilot tones;

a filter for demodulating said precoded data tones; and

means for computing filter weights using said channel state information and said interference covariance estimation.

25. The system, as claimed in claim 24, with precoding comprising of a plurality of transmitting antennas, said system comprising of:

a DFT precoder applying DFT precoding to an input stream of subcarriers;

a multi-antenna precoder applying a multi-antenna precoder scheme to each of said subcarriers to create a plurality of precoded subcarriers, wherein said multi-antenna precoder scheme is at least one of;

1-Dimensional Phase Offset Diversity (1D-POD);

antenna switching in time; and

antenna switching in frequency;

an IDFT module applying an IDFT to said plurality of precoded subcarriers to produce a plurality of signals; and

an antenna chosen from said plurality of antennas transmitting a signal chosen from said plurality of signals using, wherein said antenna is specific to said signal and each of said plurality of signals is transmitted from a distinct antenna chosen from said plurality of antennas.

26. The system as claimed in claim 25, wherein said DFT-S-OFDMA system is configured to transmit each of said subcarriers using an identical precoder scheme.

27. The system as claimed in claim 24, wherein said system comprising of:

a DFT precoder applying DFT precoding to an input stream of subcarriers, wherein said subcarriers comprise of Physical Resource Units (PRUs);

a subcarrier mapping module performing subcarrier mapping on output of said DFT precoder;

an IDFT module performing IDFT on output of said subcarrier mapping module;

a cyclic prefix module adding cyclic prefix to output of said IDFT module;

a first antenna from said plurality of transmitting antennas transmitting output of said cyclic prefix module;

a second antenna from said plurality of transmitting antennas transmitting output of said cyclic prefix module multiplied with a PRU specific phase rotation; and

subsequent antennas transmitting output of said cyclic prefix module multiplied with a phase rotation, wherein said phase rotation relies on PRU and specific antenna.

28. The system as claimed in claim 27, wherein said DFT-S-OFDMA system is configured to transmit each of said subcarriers using an identical precoder.

29. The system as claimed in claim 24, wherein said system comprising of:

a DFT precoder applying DFT precoding to an input stream of subcarriers;

a subcarrier mapping module performing subcarrier mapping on output of said DFT precoder;

a multiplication module for multiplying each of said subcarriers with a plurality of complex weights, where said number of plurality of said complex weights is equal to number of said plurality of transmitting antennas;

an IDFT module performing IDFT on each of said subcarriers to create a plurality of signals; and

said plurality of antennas transmitting said plurality of signals, wherein each signal is transmitted from a distinct antenna.

30. The system as claimed in claim 29, wherein said multiplication module is configured to change magnitude and phase of said complex weight depending on an antenna from said plurality of antennas, wherein said antenna is used to transmit a subcarrier from said plurality of subcarriers.

31. The system as claimed in claim 29, wherein said DFT-S-OFDMA system is configured to transmit each of said subcarriers using an identical precoder.

32. The system as claimed in claim 24, wherein, said system comprising of:

a modulator modulating FEC encoded data;

a splitting module splitting said modulating FEC encoded data into a plurality of data sets, where number of said plurality of data sets is equal to said number of said plurality of antennas;

a subcarrier mapper modulating each of said plurality of data sets onto contiguous subcarriers;

a DFT-S-OFDMA transmitter encoding each of said plurality of data sets; and

distinct antennas chosen from said plurality of antennas transmitting each of said plurality of data sets.

33. The system as claimed in claim 24, wherein, said system comprising of:

a modulator modulating FEC encoded data;

a splitting module splitting said modulating FEC encoded data into a plurality of data sets, where number of said plurality of data sets is equal to said number of said plurality of antennas;

a DFT module performing DFT operation on each of said data sets to create a set of DFT precoded data;

a modulator modulating each of said DFT precoded data onto contiguous subcarriers to create DFT precoded data sets;

a precoder precoding each of said plurality of DFT precoded data sets using a multi-antenna precoder for a subset of said plurality of antennas to create a plurality of multi-antenna DFT precoded data streams;

an IDFT module performing IDFT on each of said plurality of plurality of multi-antenna DFT precoded data streams to obtain multi-antenna precoded data streams;

a multi-antenna mapper mapping said multi-antenna precoded data streams to said plurality of antennas; and

distinct antennas chosen from said plurality of antennas transmitting each of said plurality of multi-antenna precoded data streams.

34. The system as claimed in claim 33, wherein said multi-antenna precoder is configured to vary mapping of said precoded data sets with one of time and frequency.

35. An OFDM system with precoding comprising of a plurality of transmitting antennas, said system comprising of:

means for estimating channel state information using said precoded pilot tones;

means for estimating interference covariance estimation using said precoded pilot tones;

a filter for demodulating said precoded data tones; and

means for computing filter weights using said channel state information and said interference covariance estimation.

36. The system as claimed in claim 35, wherein said system comprising at least one means adapted for transmitting elements of y simultaneously from said N_t antennas, where y=W(p,q)s_k,l, further wherein s_k,l denotes signal present in kth subcarrier and the lth OFDM symbol contained in the (p,q)th unit of said stream, p is frequency index of y, q is time index of y and W(p,q) is a N_t×

1 vector.