Reception and measurement of MIMO-OFDM signals with a single receiver

• US 8,238,463 B1
• Filed: 06/16/2008
• Issued: 08/07/2012
• Est. Priority Date: 06/14/2007
• Status: Active Grant

• Current Assignee: University of South Florida (State University System of Florida)
• Original Assignee: University of South Florida (State University System of Florida)
• Inventors: Arslan, Huseyin, Sahin, Mustafa Emin
• Primary Examiner(s): Williams, Lawrence B
• Application Number:
  US12/139,887
• Time in Patent Office: 1,513 Days
• Field of Search: 375/267, 375/269, 375/273, 375/279, 375/316, 375/329, 375/340, 375/346, 375/350, 375362-365, 375/320, 370/281, 370/295, 370/465, 370/480, 370/491, 370/500, 455/39, 455/91, 455/112, 455/216, 455/500, 455/516
• US Class Current: 375/267
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04L 1/0606 Space-frequency coding
• CPC Class Codes: H04L 1/0631 Receiver arrangements
• CPC Class Codes: H04L 1/0668 Orthogonal systems, e.g. using Alamouti codes
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 27/2655 Synchronisation arrangements
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver

Abstract

A method of receiving Multiple Input Multiple Output—Orthogonal Frequency Division Multiple Accessing (MIMO-OFDMA) signals using a single receiver rather than multiple receivers and performing measurements specific to various parts of MIMO-OFDMA systems using all measurable parameters of MIMO-OFDMA systems is disclosed. In addition, a method of receiving and completing impairment estimation of WiMAX MIMO signals using a single receiver according to the IEEE 802.16 standards is provided.

Claims

1. A method of processing a received signal having a first plurality of subcarriers from a first transmitter carried over a first channel and a second plurality of subcarriers from a second transmitter carried over a second channel, wherein the first plurality of subcarriers comprises a first plurality of subcarrier pilots and the second plurality of subcarriers comprises a second plurality of subcarrier pilots, the method comprising:

estimating a first impairment parameter for the first plurality of subcarrier pilots;

estimating a second impairment parameter for the second plurality of subcarrier pilots;

removing the first estimated impairment parameter from at least one of the first plurality of subcarrier pilots;

removing the second estimated impairment parameter from at least one of the second plurality of subcarrier pilots;

estimating the first channel using the at least one of the first plurality of subcarrier pilots with the impairment parameter removed;

estimating the second channel using the at least of one of the second plurality of subcarrier pilots with the impairment parameter removed; and

decoding the received signal according to Alamouti space-time based coding using the channel estimation of the first channel and the channel estimation of the second channel.

2. The method of claim 1, wherein each of the first plurality of subcarriers is orthogonal to a corresponding subcarrier in the second plurality of subcarriers.

3. The method of claim 1, wherein Alamouti coding was applied at the transmitters to subcarriers in two consecutive time symbols.

4. A method of processing a received signal having a first plurality of subcarriers from a first transmitter carried over a first channel and a second plurality of subcarriers from a second transmitter carried over a second channel, wherein the first plurality of subcarriers comprises a first plurality of subcarrier pilots and the second plurality of subcarriers comprises a second plurality of subcarrier pilots, the method comprising:

estimating a first impairment parameter for the first plurality of subcarrier pilots;

estimating a second impairment parameter for the second plurality of subcarrier pilots;

removing the first estimated impairment parameter from at least one of the first plurality of subcarrier pilots;

removing the second estimated impairment parameter from at least one of the second plurality of subcarrier pilots;

estimating the first channel using the at least one of the first plurality of subcarrier pilots with the impairment parameter removed;

estimating the second channel using the at least of one of the second plurality of subcarrier pilots with the impairment parameter removed; and

decoding the received signal according to Alamouti space-frequency based coding using the channel estimation of the first channel and the channel estimation of the second channel.

5. The method of claim 4, wherein each of the first plurality of subcarriers is orthogonal to a corresponding subcarrier in the second plurality of sub carriers.

6. The method of claim 4, wherein Alamouti coding was applied at the transmitters to adjacent subcarriers in the same time symbol.

7. A method of processing a received signal having a first plurality of subcarrier pilots from a first transmitter carried over a first channel and a second plurality of subcarriers pilots from a second transmitter carried over a second channel, the method comprising:

estimating a first impairment parameter for the first plurality of subcarrier pilots;

estimating a second impairment parameter for the second plurality of subcarrier pilots;

removing the first estimated impairment parameter from at least one of the first plurality of subcarrier pilots;

removing the second estimated impairment parameter from at least one of the second plurality of subcarrier pilots;

estimating the first channel using the at least one of the first plurality of subcarrier pilots with the impairment parameter removed;

estimating the second channel using the at least of one of the second plurality of subcarrier pilots with the impairment parameter removed;

providing a first hypothesis signal which represents a possible variation a signal transmitted by the first transmitter;

providing a second hypothesis signal which represents a possible variation of a signal transmitted by the second transmitter;

applying the channel estimation of the first channel to the first hypothesis signal;

applying the channel estimation of the second channel to the second hypothesis signal; and

combining the first hypothesis signal with the first channel estimation applied and the second hypothesis signal with the second channel estimation applied to create a first combined signal estimate.

8. The method of claim 7, further comprising:

providing a third hypothesis signal which represents a possible variation of a signal transmitted by the first transmitter;

providing a fourth hypothesis signal which represents a possible variation of a signal transmitted by the second transmitter;

applying the channel estimation of the first channel to the third hypothesis signal;

applying the channel estimation of the second channel to the fourth hypothesis signal;

combining the third hypothesis signal with the first channel estimation applied and the fourth hypothesis signal with the second channel estimation applied to create a second combined signal estimate; and

determining the most accurate combined signal by comparing each combined signal estimate with the received signal.

9. The method of claim 8, wherein determining the most accurate combined signal by comparing each combined signal estimate with the received signal further comprises:

determining the combined signal yielding a minimum Euclidian distance to the received signal, the Euclidian distance being calculated according to the relation;

ε

(k)=|Y(k)−

Ĥ

₁(k)x₁−

Ĥ

₂(k)x₂|²,

wherein Y(k) is the received signal, x₁ and x₂ are the two hypothesis signals, and Ĥ

₁(k) and Ĥ

₂(k) are the corresponding channel estimates.

10. The method of claim 7, wherein each of the first plurality of subcarriers is orthogonal to the corresponding subcarriers in the second plurality of sub carriers.

11. The method of claim 8, wherein the third hypothesis signal is different from the first hypothesis signal.

12. The method of claim 8, wherein the fourth hypothesis signal is different from the second hypothesis signal.

13. A method of processing a received signal comprising a first signal from a first transmitter transmitted over a first channel and a second signal from a second transmitter transmitted over a second channel, the method comprising:

estimating the first channel;

estimating the second channel;

providing a first set of hypothesis signals, wherein each hypothesis signal represents a possible variation of the first signal;

providing a second set of hypothesis signals, wherein each hypothesis signal represents a possible variation of the second signal;

applying the channel estimation of the first channel to the hypothesis signals in the first set;

applying the channel estimation of the second channel to the hypothesis signals in the second set; and

combining the first set hypothesis signals with the first channel estimation applied and the second set hypothesis signals with the second channel estimation applied to create a set of combined signal estimates; and

determining the most accurate combined signal by comparing each combined signal estimate with the received signal.

14. The method of claim 13, wherein determining the most accurate combined signal by comparing each combined signal estimate with the received signal further comprises:

determining the combined signal yielding a minimum Euclidian distance to the received signal, the Euclidian distance being calculated according to the relation;

ε

(k)=|Y(k)−

Ĥ

₁(k)x₁−

Ĥ

₂(k)x₂|²,

wherein Y(k) is the received signal, x₁ and x₂ are the two hypothesis signals, and Ĥ

₁(k) and Ĥ

₂(k) are the corresponding channel estimates.

15. The method of claim 13, wherein the hypothesis signals in the first set are all different.

16. The method of claim 13, wherein the hypothesis signals in the second set are all different.