Flexible MIMO resource allocation through cross-correlation nulling and frequency domain segmented receiver processing
An access node in a wireless communication network receives a transmission that includes first and second signals. The first and second signals may be layers of a multiple-input multiple-output transmission and may also be from first and second terminal nodes. The access node derives first and second local reference signals from the transmission received using first and second antennas and estimates channel transfer functions associated with the channel through with the transmission is received. Estimating the channel transfer function can include correlating at least a portion of an expected reference signal associated with the first signal with a corresponding portion of the first local reference signal and correlating at least a portion of an expected reference signal associated with the second signal with a corresponding portion of the second local reference signal. The expected reference signal portions used to estimate the channel transfer functions may be non-orthogonal.
1. An access node, comprising:
a first radio module configured to receive, using a first antenna, a transmission including a first signal and a second signal;
a second radio module configured to receive, using a second antenna, the transmission; a memory module; and a processor module coupled to the first and second radio modules and the memory module and configured to:
derive a first local reference signal from the received transmission of the first radio module;
derive a second local reference signal from the received transmission of the second radio module; and
estimate one or more channel transfer functions associated with the transmission, the estimation of the one or more channel transfer functions including correlating at least a portion of an expected reference signal associated with the first signal with at least a portion of the first local reference signal, and correlating at least a portion of an expected reference signal associated with the second signal with at least a portion of the second local reference signal,
wherein the at least a portion of the expected reference signal associated with the first signal and the at least a portion of the expected reference signal associated with the second signal are non-orthogonal to each other.
2. The access node of claim 1 , wherein the expected reference signal associated with the first signal and the expected reference signal associated with the second signal are partially overlapping in frequency.
3. The access node of claim 1 , wherein the expected reference signal associated with the first signal and the expected reference signal associated with the second signal are different sizes.
4. The access node of claim 1 , wherein the first signal and the second signal are associated with different layers of a multiple-input multiple-output transmission.
5. The access node of claim 1 , wherein the processor is further configured to determine decoded data conveyed in the received transmission using the one or more estimated channel transfer functions.
6. The access node of claim 1 , wherein the estimation of the one or more channel transfer functions further includes applying a correction to the channel transfer function, the correction including correlating the at least a portion of the expected reference signal associated with the first signal with a corresponding portion of the second local reference signal, or correlating the at least a portion of the expected reference signal associated with the second signal with a corresponding portion of the first local reference signal.
7. The access node of claim 1 , wherein the reference signals are demodulation reference signals.
8. The access node of claim 1 , wherein the estimation of the one or more channel transfer functions further includes:
partitioning an aggregate frequency range into frequency range segments, the aggregate frequency range containing frequencies occupied by the first signal or the second signal; and
estimating a channel transfer function for each of the frequency range segments.
9. The access node of claim 8 , wherein the frequency range segments are selected based at least in part on frequency selectivity of a channel associated with the received transmission.
10. The access node of claim 8 , wherein the frequency range segments are selected based at least in part on frequencies occupied by the first signal and frequencies occupied by the second signal.
11. The access node of claim 8 , wherein partitioning the aggregate frequency range includes:
dividing the aggregate frequency range into one or more frequency range sub-bands; and
segmenting the frequency range sub-bands into one or more frequency range segments.
12. The access node of claim 11 , wherein dividing the aggregate frequency range into one or more frequency range sub-bands uses predetermined sub-band sizes.
13. The access node of claim 11 , wherein dividing the aggregate frequency range into one or more frequency range sub-bands includes:
analyzing a channel associated with the received transmission for frequency selectivity; and
dividing the aggregate frequency range into the one or more frequency range sub-bands based on analyzed frequency selectivity.
14. The access node of claim 11 , wherein the frequency range segments include segments of the frequency range sub-bands having unique combinations of first and second signals.
15. A method for receiving communications in a wireless communication system, the method comprising:
receiving, using a first antenna, a transmission that includes a first signal and a second signal;
receiving the transmission using a second antenna;
deriving a first local reference signal from the transmission received using the first antenna; and
deriving a second local reference signal from the transmission received using the second antenna; and
estimating one or more channel transfer functions associated with the transmission, the estimating including correlating at least a portion of an expected reference signal associated with the first signal with at least a portion of the first local reference signal, and correlating at least a portion of an expected reference signal associated with the second signal with at least a portion of the second local reference signal,
wherein the at least a portion of the expected reference signal associated with the first signal and the at least a portion of the expected reference signal associated with the second signal are non-orthogonal to each other.
16. The method of claim 15 , wherein the expected reference signal associated with the first signal and the expected reference signal associated with the second signal are partially overlapping in frequency.
17. The method of claim 15 , wherein the expected reference signal associated with the first signal and the expected reference signal associated with the second signal are different sizes.
18. The method of claim 15 , wherein the first signal are the second signal are associated with different layers of a multiple-input multiple-output transmission.
19. The method of claim 15 , further comprising determining decoded data conveyed in the received transmission using the one or more estimated channel transfer functions.
20. The method of claim 15 , wherein the estimating further includes applying a correction to the channel transfer function, the correction including correlating the at least a portion of the expected reference signal associated with the first signal with a corresponding portion of the second local reference signal, or correlating the at least a portion of the expected reference signal associated with the second signal with a corresponding portion of the first local reference signal.
21. The method of claim 15 , wherein the reference signals are demodulation reference signals.
22. The method of claim 15 , wherein estimating the one or more channel transfer functions further includes:
partitioning an aggregate frequency range into frequency range segments, the aggregate frequency range containing frequencies occupied by the first signal or the second signal; and
estimating a channel transfer function for each of the frequency range segments.
23. The method of claim 22 , wherein the frequency range segments are selected based at least in part on frequency selectivity of a channel associated with the first signal.
24. The method of claim 22 , wherein the frequency range segments are selected based at least in part on frequencies occupied by the first signal and frequencies occupied by the second signal.
25. The method of claim 22 , wherein partitioning the aggregate frequency range includes:
dividing the aggregate frequency range into one or more frequency range sub-bands; and
segmenting the frequency range sub-bands into one or more frequency range segments.
26. The method of claim 25 , wherein dividing the aggregate frequency range into one or more frequency range sub-bands uses predetermined sub-band sizes.
27. The method of claim 25 , wherein dividing the aggregate frequency range into one or more frequency range sub-bands includes:
analyzing a channel associated with the first signal for frequency selectivity; and
dividing the aggregate frequency range into the one or more frequency range sub-bands based on analyzed frequency selectivity.
28. The method of claim 25 , wherein the frequency range segments include segments of the frequency range sub-bands having unique combinations of first and second signals.
29. A communication system, comprising:
a first terminal node including a first transmitter configured to transmit a first signal that includes a first expected reference signal;
a second terminal node including a second transmitter configured to transmit a second signal that includes a second expected reference signal,
wherein the second expected reference signal is transmitted using frequencies that partially overlap with frequencies used by the first terminal node to transmit the first expected reference signal, or wherein the second expected reference signal and the first expected reference signal are non-orthogonal to each other;
an access node comprising:
a first radio module configured to receive, using a first antenna, a transmission including the first signal and the second signal;
a second radio module configured to receive, using a second antenna, the transmission; a memory module; and a processor module coupled to the first and second radio modules and the memory module and configured to:
derive a first local reference signal from the received transmission of the first radio module;
derive a second local reference signal from the received transmission of the second radio module; and
estimate one or more channel transfer functions associated with the transmission, the estimation of the one or more channel transfer functions including
correlating at least a portion of the first expected reference signal with at least a portion of first local reference signal, and correlating at least a portion of the second expected reference signal with at least a portion of the second local reference signal,
wherein the at least a portion of the first expected reference signal and the at least a portion of the second expected reference signal are non-orthogonal to each other.