Method and system for an improved user group selection scheme with finite-rate channel state information feedback for FDD multiuser MIMO downlink transmission

1. A method for communication, the method comprising:

performing using one or more processors and/or circuits:

selecting, from a plurality of signal receiving users in a multiuser communication system, a first signal receiving user having a channel gain that is greater than a channel gain of each corresponding signal receiving user of a remaining portion of said plurality of signal receiving users; and

selecting a second signal receiving user from said remaining portion of said plurality of signal receiving users, based on a feedback information comprising orthogonality of a channel direction of said second signal receiving user with respect to a channel direction of said first user.

2. The method according to claim 1 , wherein said feedback information comprises a channel gain of said second signal receiving user.

3. The method according to claim 1 , wherein said communication system comprises a frequency division duplex (FDD) multiuser communication system.

4. The method according to claim 1 , wherein said selected second signal receiving user has a channel gain that is greater than a feedback channel gain corresponding to said remaining portion of said plurality of signal receiving users.

5. The method according to claim 1 , wherein said channel direction of said selected second signal receiving user is approximately orthogonal to said channel direction said first signal receiving user.

6. The method according to claim 1 , comprising determining a quantized channel direction of said selected first signal receiving user for said selecting said at least said second signal receiving user.

7. The method according to claim 1 , wherein said orthogonality of said channel direction of said second signal receiving user is based on an effective received signal-to-noise ratio (SNR) of said second signal receiving user with respect to a beam vector broadcasted within the communication system.

8. The method according to claim 1 , comprising maximizing a system capacity based on said selecting said first signal receiving user and said selecting said second signal receiving user.

9. The method according to claim 1 , comprising, if a system capacity function for said selected first signal receiving user and said selected second signal receiving user is greater than a system capacity function for said selected first signal receiving user, generating a first precoding matrix for precoding at least one transmit signal within the communication system.

10. The method according to claim 1 , comprising, if a system capacity function for said selected first signal receiving user and said selected second signal receiving user is not greater than a system capacity function for said selected first signal receiving user, generating a second precoding matrix for precoding at least one transmit signal within the communication system, wherein said second precoding matrix is determined from a complex conjugate of a quantized channel direction of said selected first signal receiving user.

11. A non-transitory machine-readable storage having stored thereon, a computer program having at least one code section for communication, the at least one code section being executable by a machine for causing the machine to perform steps comprising:

selecting, from a plurality of signal receiving users in a multiuser communication system, a first signal receiving user having a channel gain that is greater than a channel gain of each corresponding signal receiving user of a remaining portion of said plurality of signal receiving users; and

selecting a second signal receiving user from said remaining portion of said plurality of signal receiving users, based on a feedback information comprising orthogonality of a channel direction of said second signal receiving user with respect to a channel direction of said first user.

12. The machine-readable storage according to claim 11 , wherein said feedback information comprises a channel gain of said second signal receiving user.

13. The machine-readable storage according to claim 11 , wherein said communication system comprises a frequency division duplex (FDD) multiuser communication system.

14. The machine-readable storage according to claim 11 , wherein said selected second signal receiving user has a channel gain that is greater than a feedback channel gain corresponding to said remaining portion of said plurality of signal receiving users.

15. The machine-readable storage according to claim 11 , wherein said channel direction of said selected second signal receiving user is approximately orthogonal to said channel direction said first signal receiving user.

16. The machine-readable storage according to claim 11 , comprising code for determining a quantized channel direction of said selected first signal receiving user for said selecting said at least said second signal receiving user.

17. The machine-readable storage according to claim 11 , wherein said orthogonality of said channel direction of said second signal receiving user is based on an effective received signal-to-noise ratio (SNR) of said second signal receiving user with respect to a beam vector broadcasted within the communication system.

18. The machine-readable storage according to claim 11 , comprising code for maximizing a system capacity based on said selecting said first signal receiving user and said selecting said second signal receiving user.

19. The machine-readable storage according to claim 11 , comprising code for generating a first precoding matrix for precoding at least one transmit signal within the communication system, if a system capacity function for said selected first signal receiving user and said selected second signal receiving user is greater than a system capacity function for said selected first signal receiving user.

20. The machine-readable storage according to claim 11 , comprising code for generating a second precoding matrix for precoding at least one transmit signal within the communication system, if a system capacity function for said selected first signal receiving user and said selected second signal receiving user is not greater than a system capacity function for said selected first signal receiving user, wherein said second precoding matrix is determined from a complex conjugate of a quantized channel direction of said selected first signal receiving user.

21. A system for communication, the system comprising:

one or more circuits that enables selecting, from a plurality of signal receiving users in a multiuser communication system, a first signal receiving user having a channel gain that is greater than a channel gain of each corresponding signal receiving user of a remaining portion of said plurality of signal receiving users; and

said one or more circuits enables selecting a second signal receiving user from said remaining portion of said plurality of signal receiving users, based on a feedback information comprising orthogonality of a channel direction of said second signal receiving user with respect to a channel direction of said first user.

22. The system according to claim 21 , wherein said feedback information comprises a channel gain of said second signal receiving user.

23. The system according to claim 21 , wherein said communication system comprises a frequency division duplex (FDD) multiuser communication system.

24. The system according to claim 21 , wherein said selected second signal receiving user has a channel gain that is greater than a feedback channel gain corresponding to said remaining portion of said plurality of signal receiving users.

25. The system according to claim 21 , wherein said channel direction of said selected second signal receiving user is approximately orthogonal to said channel direction said first signal receiving user.

26. The system according to claim 21 , wherein said one or more circuits enables determining a quantized channel direction of said selected first signal receiving user for said selecting said at least said second signal receiving user.

27. The system according to claim 21 , wherein said orthogonality of said channel direction of said second signal receiving user is based on an effective received signal-to-noise ratio (SNR) of said second signal receiving user with respect to a beam vector broadcasted within the communication system.

28. The system according to claim 21 , wherein said one or more circuits enables maximizing a system capacity based on said selecting said first signal receiving user and said selecting said second signal receiving user.

29. The system according to claim 21 , wherein said one or more circuits enables generating a first precoding matrix for precoding at least one transmit signal within the communication system, if a system capacity function for said selected first signal receiving user and said selected second signal receiving user is greater than a system capacity function for said selected first signal receiving user.

30. The system according to claim 21 , wherein said one or more circuits enables generating a second precoding matrix for precoding at least one transmit signal within the communication system, if a system capacity function for said selected first signal receiving user and said selected second signal receiving user is not greater than a system capacity function for said selected first signal receiving user, wherein said second precoding matrix is determined from a complex conjugate of a quantized channel direction of said selected first signal receiving user.