A High Diversity Time-Space Coding and Decoding for MIMO Systems

• US 20070297528A1
• Filed: 06/27/2006
• Published: 12/27/2007
• Est. Priority Date: 06/27/2006
• Status: Active Grant

• Current Assignee: Amimon Limited (Vitec Group PLC)
• Original Assignee: Amimon Limited (Vitec Group PLC)
• Inventors: Feder, Meir, Bublil, Baruch, Doron, Eran
• Granted Patent: US 8,107,543 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: H04L 1/0631 Receiver arrangements
• CPC Class Codes: H04L 1/0662 Limited orthogonality systems
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT

Abstract

A diversity transmission scheme uses a number of antennas that is greater than the limitation of two transmitting antennas in the well-known Alamouti scheme. In an embodiment comprising four antennas, the antennas transmit in pairs such that each antenna transmits a block that is used in the Alamouti scheme. This increases the transmission rate. For example, the transmission of two signals at a given time slot increases transmission rate by a factor of two. The invention not only increases the number of antennas, but also increases the transmission rate. At the receiver end, the code is decoded without matrix inversion and without much noise enhancement. Moreover, noise enhancement stability is increased by a simple, partial interference cancellation scheme, that results in improved decoding performance.

Claims

15. A receiver for reception of a plurality of symbols transmitted using a high diversity transmission scheme that operates without explicitly inverting a matrix, the receiver comprising:

a plurality of reception antennas;

means for generating a characteristics matrix H of a transmission channel for a high diversity transmission scheme;

means for creating a conjugate transposed matrix H^T of said matrix H;

means for generating a matrix W which is an orthogonal matrix to a matrix resulting from multiplication of matrix H^T by said matrix H;

means coupled to said plurality of reception antennas for receiving a first high diversity transmission signal in a first time period and a second high diversity transmission signal in a second time period;

means for multiplying a received signal matrix of said first and second high diversity transmission signals by matrices W and H; and

means extracting symbols transmitted using said high diversity transmission scheme;

wherein said receiver receives signals from a plurality of transmission antennas, the number of transmission antennas being an even number that is greater than or equal to four.

1. A method for reception of a plurality of symbols transmitted using a high diversity transmission scheme without explicitly inverting a matrix, the method comprising the steps of:

performing matrix operations, comprising;

generating a characteristics matrix H of a transmission channel for a high diversity transmission scheme;

creating a conjugate transposed matrix H^T of said matrix H;

generating a matrix W which is an orthogonal matrix to a matrix resulting from the multiplication of matrix H^T by matrix H;

receiving a first high diversity transmission signal in a first time period and a second high diversity transmission signal in a second time period;

multiplying a received signal matrix of said first and second high diversity transmission signals by matrices W and H; and

extracting symbols transmitted using a high diversity transmission scheme;

wherein said transmission scheme is based on reception of signals received from a plurality of transmission antennas, the number of transmission antennas comprising an even number that is greater than or equal to four.

2. The method of claim 1, wherein said high diversity transmission scheme comprises the steps of:

obtaining a series of symbols for transmission, said transmission being made with an even number of transmission antennas, the number of transmission antennas comprising four or more;

transmitting at a first time period an even symbol of a plurality of even symbols on a first transmission antenna of a pair of transmission antennas and an odd symbol of a plurality of odd symbols on a second transmission antenna of said pair of transmission antennas;

generating a conjugate of each of said even symbols;

generating a negative conjugate of each of said odd symbols; and

transmitting at a second time period, immediately subsequent to said first time period, said negative conjugate symbol of said odd symbol on said first transmission antenna of said pair of transmission antennas and said conjugate symbol of said even symbol on said second transmission antenna of said pair of transmission antennas;

wherein said transmission is performed such that at each first time period a plurality of symbols for transmission equal to said even number is transmitted, and at each second time period the conjugate number of the even symbols of said plurality of symbols is sent over the odd numbered antenna and the negative conjugate number of the odd symbols of said plurality of symbols is sent over the even numbered antenna.

3. The method of claim 1, wherein the matrix resulting from multiplication H^TH is a matrix comprised of sub-matrices, wherein edge sub-matrices on a primary diagonal comprise diagonal matrices and edge sub-matrices of a secondary diagonal orthogonal matrices.

4. The method of claim 3, wherein matrix H becomes closer to an orthogonal matrix as the number of reception antennas increases.

5. The method of claim 3, further comprising the step of:

determining which of two received symbols pairs is less impacted by channel noise by using coefficients |a|² and |b|² of said primary diagonal of matrix W.

6. The method of claim 5, wherein if |a|² is smaller than |b|², then a second pair of received symbols has suffered less from channel noise.

7. The method of claim 5, wherein if |b|² is smaller than |a|², then a first pair of received symbols is less impacted by channel noise.

8. The method of claim 5, further comprising the step of:

using symbols that were less impacted by noise to improve reception of an other symbols pair.

9. A receiver, comprising:

means for reception of a high-diversity transmission scheme comprising transmission from an even number of transmission antennas which is greater than or equal to four, said reception means implementing the steps of the method of claim 1.

10. A system comprising a transmitter and a receiver, said receiver comprising the receiver of claim 9, wherein said transmitter and said receiver are physically separated.

11. The system of claim 10, wherein said transmitter sends streams of an even number of symbols over an even number of transmission antennas, wherein the number of antennas is greater than or equal to four.

12. The system of claim 11, wherein, during a first time period said transmitter transmits symbols positioned in even locations in said even number of symbols on even numbered antennas of said transmission antennas, and said transmitter transmits symbols positioned in odd locations in said even number of symbols on odd numbered antennas of said transmission antennas.

13. The system of claim 12, wherein at a second time period immediately subsequent to said first time period said transmitter transmits on an even numbered antenna a negative conjugate symbol of the symbols transmitted during said first time period on an odd numbered antenna, and transmits on an odd numbered antenna a conjugate symbol of the symbols transmitted during said first time period on an even numbered antenna.

14. A transceiver, comprising:

means for reception of a high-diversity transmission scheme comprising transmission from an even number of transmission antennas which is greater than or equal to four, said reception means implementing the steps of the method of claim 1.

16. The receiver of claim 15, wherein the matrix resulting from multiplication H^TH is a matrix comprised of sub-matrices, wherein edge sub-matrices on a primary diagonal comprises diagonal matrices, and edge sub-matrices of a secondary diagonal comprise orthogonal matrices.

17. The receiver of claim 16, wherein the matrix H becomes closer to an orthogonal matrix as the number of reception antennas increases.

18. The receiver of claim 16, further comprising:

means for determining which of two received symbol pairs is less impacted by channel noise by using coefficients |a|² and |b|² of a primary diagonal of the matrix W.

19. The receiver of claim 18, wherein if |a|² is smaller than |b|², then said means for determining which of two received symbols pairs is less impacted by channel noise determines that a second pair of received symbols is less impacted by channel noise.

20. The receiver of claim 18, wherein if |b|² is smaller than |a|², then said means for determining which of two received symbols pairs is less impacted by channel noise determines that a first pair of received symbols is less impacted by channel noise.

21. The receiver of claim 18, further comprising:

means for using symbols that were less impacted by noise to improve reception of other symbols pair.

22. A system comprising a transmitter and a receiver, said receiver comprising the receiver of claim 21, wherein said transmitter and said receiver are physically separated.

23. The system of claim 22, wherein said transmitter sends streams of an even number of symbols over an even number of transmission antennas, wherein the number of antennas is greater than or equal to four.

24. The system of claim 23, wherein, during a first time period said transmitter transmits symbols positioned in even locations in said even number of symbols on even numbered antennas of said transmission antennas, and said transmitter transmits symbols positioned in odd locations in said even number of symbols on odd numbered antennas of said transmission antennas.

25. The system of claim 24, wherein at a second time period immediately subsequent to said first time period said transmitter transmits on an even numbered antenna a negative conjugate symbol of the symbols transmitted during said first time period on an odd numbered antenna, and transmits on an odd numbered antenna a conjugate symbol of the symbols transmitted during said first time period on an even numbered antenna.

26. A transceiver, comprising:

means for reception and transmission of symbols in accordance with a high-diversity transmission scheme that comprises the transmission from an even number of transmission antennas which is greater than or equal to four, said reception being implemented by the receiver of claim 11.

21-1. The receiver of claim 15, further comprising:

a transmitter for transmitting said high-diversity transmission scheme comprising;

means for obtaining a series of symbols for transmission, said transmission being made with an even number of transmission antennas, the number of transmission antennas comprising four or more;

means for transmitting at a first time period an even symbol of said even symbols on a first transmission antenna of a pair of transmission antennas and an odd symbol of said odd symbols on a second transmission antenna of said pair of transmission antennas;

means for generating a conjugate of each of said even symbols;

means generating a negative conjugate of each of said odd symbols;

means for transmitting at a second time period, immediately subsequent to said first time period, said negative conjugate symbol of said odd symbol on said first transmission antenna of said pair of transmission antennas and said conjugate symbol of said even symbol on said second transmission antenna of said pair of transmission antennas;

wherein said transmission is performed such that at each first time period a plurality of symbols for transmission equal to said even number is transmitted, and at each second time period said conjugate number of the even symbols of said plurality of symbols is sent over an odd numbered antenna and said negative conjugate number of the odd symbols of said plurality of symbols is sent over an even numbered antenna.