Method and apparatus for performing sequential closed loop multiple input multiple output (MIMO)
In a communication system using closed loop multiple input/multiple output MIMO, beam forming information may be fed back from a receiver to a transmitter sequentially over a number of frames. The beam forming matrices that are fed back may be quantized.
1. A wireless device comprising:
a beam former to multiply input data symbols by a beam forming matrix to form signals to be directed to multiple antennas for transmission into a MIMO channel as a data frame;
a first storage area to store a beam forming matrix that was used by said beam former during generation of a most recently transmitted data frame;
a second storage area to store a feedback matrix received from a remote device; and
a combiner to combine said beam forming matrix and said feedback matrix to generate an updated beam forming matrix for use by said beam former during generation of a subsequent data frame, wherein said combiner is a multiplication unit that right multiplies said beam forming matrix with said feedback matrix to generate said updated beam forming matrix.
2. The wireless device of claim 1 , wherein:
said feedback matrix received from said remote device is quantized.
3. The wireless device of claim 1 , wherein:
said wireless device is for use in a wireless network where data is transmitted in wireless frame exchange sequences, wherein said feedback matrix is received from said remote device as part of a response frame that also includes an acknowledgement packet.
4. The wireless device of claim 3 , wherein:
said combiner generates updated beam forming matrices for multiple successive data frames transmitted during a frame exchange sequence.
5. A wireless device comprising:
at least one dipole antenna;
a beam former to multiply input data symbols by a beam forming matrix to form signals to be directed to multiple antennas for transmission into a MIMO channel as a data frame, said multiple antennas including said at least one dipole antenna;
a first storage area to store a beam forming matrix that was used by said beam former during generation of a most recently transmitted data frame;
a second storage area to store a feedback matrix received from a remote device; and
a combiner to combine said beam forming matrix and said feedback matrix to generate an updated beam forming matrix for use by said beam former during generation of a subsequent data frame, wherein said combiner is a multiplication unit that right multiplies said beam forming matrix with said feedback matrix to generate said updated beam forming matrix.
6. The wireless device of claim 5 , wherein:
said combiner is a multiplication unit.
7. The wireless device of claim 5 , wherein:
said feedback matrix received from said remote device is quantized.
8. An article comprising a computer readable storage medium having instructions stored thereon that, when executed by a computing platform, operate to:
receive a signal Y i from a MIMO channel, said signal Y i including data symbols X i that were matrix multiplied by a beam forming matrix V i within a remote transmitter before being transmitted into said MIMO channel, said MIMO channel having a channel matrix H i ;
use said signal Y i to determine a combined channel {tilde over (H)} i that includes effects of both the beam forming matrix V i and the channel matrix H i ;
perform a singular value decomposition (SVD) of the combined channel {tilde over (H)} i to determine a beam forming matrix {tilde over (V)} i representing a correction that is needed for the beam forming matrix V i ; and
transmit said beam forming matrix {tilde over (V)} i to said remote transmitter to be multiplied with said beam forming matrix V i to generate a new beam forming matrix V i+1 for use in a subsequent data transmission from said remote transmitter.
9. The article of claim 8 , wherein said instructions further operate to:
quantize said beam forming matrix {tilde over (V)} i before it is transmitted.
10. The article of claim 8 , wherein said instructions further operate to:
quantize said beam forming matrix {tilde over (V)} i using vector quantization techniques before said beam forming matrix {tilde over (V)} i is transmitted.
11. The article of claim 8 , wherein said instructions further operate to:
quantize said beam forming matrix {tilde over (V)} i using adaptive quantization techniques before said beam forming matrix {tilde over (V)} i is transmitted.
12. A wireless device comprising:
a plurality of antennas; and
a digital processing device to support communication with a remote wireless device via a multiple input/multiple output (MIMO) channel, said digital processing device being programmed to:
receive a signal Y i from said MIMO channel, said signal Y i including data symbols X i that were matrix multiplied by a beam forming matrix V i within a transmitter of said remote wireless device before being transmitted into said MIMO channel, said MIMO channel having a channel matrix H i ;
use said signal Y i to determine a combined channel {tilde over (H)} i that includes effects of both the beam forming matrix V i and the channel matrix H i ;
perform singular value decomposition (SVD) of the combined channel {tilde over (H)} i to determine a beam forming matrix {tilde over (V)} i representing a correction that is needed for the beam forming matrix V i ; and
transmit said beam forming matrix {tilde over (V)} i to said remote wireless device to be multiplied with said beam forming matrix V i to generate a new beam forming matrix V i+1 for use in a subsequent data transmission from said remote wireless device.
13. The wireless device of claim 12 , wherein:
said communication with said remote wireless device includes a frame exchange sequence with said remote wireless device; and
receive, use, perform, and transmit are repeated for multiple successive data frames received during said frame exchange sequence.
14. The wireless device of claim 12 , wherein:
said communication with said remote wireless device includes a frame exchange sequence with said remote wireless device; and
transmission of said beam forming matrix {tilde over (V)} i to said remote wireless device includes transmitting said beam forming matrix {tilde over (V)} i as part of a response frame that also includes an acknowledgement packet.
15. The wireless device of claim 12 , wherein said digital processing device is programmed to:
quantize said beam forming matrix {tilde over (V)} i before transmitting it to said remote wireless device.
16. The wireless device of claim 12 , wherein said digital processing device is programmed to:
quantize said beam forming matrix {tilde over (V)} i using vector quantization techniques before transmitting it to said remote wireless device.
17. The wireless device of claim 12 , wherein said digital processing device is programmed to:
quantize said beam forming matrix {tilde over (V)} i using Grassmanian beam forming techniques before transmitting it to said remote wireless device.
18. The wireless device of claim 12 , wherein said digital processing device is programmed to:
quantize said beam forming matrix {tilde over (V)} i using adaptive quantization techniques before transmitting it to said remote wireless device.
19. The wireless device of claim 12 , wherein said digital processing device is programmed to:
quantize said beam forming matrix {tilde over (V)} i using differential quantization techniques before transmitting it to said remote wireless device.