WiFi antenna selection with beamforming

1. A wireless transceiver for wireless communication on a selected orthogonal frequency division multiplexed (OFDM) communication channel of a wireless local area network (WLAN); and the wireless transceiver comprising:

a number of antennas;

a plurality of components coupled to one another to form receive chains and transmit chains lesser in number than the number of antennas, and switchably coupled to the antennas for multiple-input multiple-output (MIMO) wireless communications on OFDM tones of the selected communication channel;

a beamform antenna selection circuit coupled to the antennas and the plurality of components:

to generate a multi-tone sounding signal on a targeted transceiver wherein the multi-tone sounding signal comprises a multi-tone OFDM signal with separate tones applicable to a plurality of distinct subsets of the antennas;

to determine performance of the plurality of distinct subsets based on sounding feedback of the multi-tone sounding signal from the targeted transceiver,

to select a highest ranked subset of the antennas to couple to the transmit chains with the number of antenna and receiving sounding feedback from the targeted transceiver, and

to switchably couple the transmit chains to the highest ranked subset of the antennas for beamformed transmission of subsequent data communication packets to the targeted transceiver; and

a center frequency shifter circuit coupled to the antennas:

to vary a center frequency of each of the antenna relative to the others for the sounding, and

to set a same frequency for the highest ranked subset of the antennas for beamformed transmission of subsequent data communication packets to the targeted transceiver.

2. The wireless transceiver of claim 1 , wherein the sounding feedback is in the form of an actual unitary beamforming matrix and the per tone diagonal matrix is related to a per tone signal-to-noise ratio (SNR).

3. The wireless transceiver of claim 1 , further comprising:

the beamform antenna selection circuit to select the highest ranked subset of the antennas to couple to the transmit chains by sounding the targeted transceiver with the plurality of distinct subsets of the antennas within each multi-tone sounding signal.

4. The wireless transceiver of claim 1 , further comprising:

the beamform antenna selection circuit to select the highest ranked subset of the antennas to couple to the transmit chains by sounding the targeted transceiver with a sounding packet in which neighboring ones of the OFDM tones are spatially mapped to a plurality of distinct subsets of the antennas.

5. The wireless transceiver of claim 1 , further comprising:

the beamform antenna selection circuit to select the highest ranked subset of the antennas to couple to the transmit chains by sounding the targeted transceiver with distinct combinations C(N, T) of chain-to-antenna couplings in each sounding; where “N” is the number of antennas and “T” is the number of transmit chains.

6. The wireless transceiver of claim 1 , further comprising:

a transmit chain expander circuit to expand, during transmission of a sounding packet, the number of transmit chains to match the number of antennas associated with the plurality of distinct subsets of the antenna sounded in the sounding packet.

7. The wireless transceiver of claim 1 , further comprising:

a transmit chain expander circuit to expand, during transmission of a sounding packet, the number of transmit chains to match the number of antennas and during transmission of subsequent communication data packets to the targeted transceiver to couple each of the transmit chains to a selected one of the antennas.

8. The wireless transceiver of claim 1 , further comprising:

the number of antennas comprises “N”;

the plurality of components form the number “T” transmit chains; and

a transmit chain expander circuit to combine the transmit chains into a number N distinct combinations each coupled to corresponding one of the number N antenna during the sounding, and to couple the transmit chains to the highest ranked subset of T of the N antenna during subsequent transmission of data communication packets to the targeted transceiver.

9. The wireless transceiver of claim 1 , further comprising:

a transmit chain expander circuit to combine the transmit chains into distinct combinations each coupled to corresponding one of the antenna during the sounding.

10. A very large scale integrated (VLSI) circuit to couple between transmit chains of a wireless orthogonal frequency division multiplexed (OFDM) transceiver and an array of antennas greater in number than a number of the transmit chains, and the VLSI circuit comprising:

a transmit chain expander circuit to expand during transmission of a sounding packet, by the wireless OFDM transceiver, comprising a multi-tone sounding signal with separate tones applicable to a plurality of distinct subsets of the antennas, the number of transmit chains to match a number of antennas sounded in the sounding packet, to determine performance of the plurality of distinct subsets of the antennas based on multi-tone sounding feedback, the transmit chain expander to vary a center frequency of each of the antenna relative to the other antennas for transmission of the sounding packet, and during beamformed transmission of subsequent communication data packets to a targeted transceiver to couple each of the transmit chains to a selected one of the antennas in the array in view of the multi-tone sounding feedback, wherein each selected one of the antennas is set to a same center frequency for beamformed transmission of subsequent communication.

11. The VLSI circuit of claim 10 , further comprising:

the transmit chain expander circuit to both combine the transmit chains into distinct combinations each coupled to corresponding one of the antenna during transmission of the sounding packet.

12. A method for operating wireless transceiver on an orthogonal frequency division multiplexed (OFDM) communication channel of a wireless local area network (WLAN); and the method comprising:

providing a number of antennas;

providing a plurality of components coupled to one another to form receive chains and transmit chains lesser in number than the number of provided antennas;

sounding a targeted transceiver on the WLAN via a multi-tone sounding signal on a targeted transceiver wherein the multi-tone sounding signal comprises a multi-tone OFDM signal with separate tones applicable to a plurality of distinct subsets of the antennas;

varying a center frequency of each of the provided antenna relative to one another for the sounding;

determining performance of the plurality of distinct subsets based on sounding feedback of the multi-tone sounding signal from the targeted transceiver;

selecting a highest ranked subset of the provided antennas to couple to the transmit chains based on the sounding act;

switchably coupling the transmit chains to the highest ranked subset of the antennas selected in the selecting act;

setting a same frequency for the highest ranked subset of the antennas for beamformed transmission of subsequent data communication packets to the targeted transceiver; and

transmitting beamformed subsequent data communication packets to the targeted transceiver via the subset of the antennas coupled to the transmit chains in the switchable coupling act.

13. The method for operating a wireless transceiver of claim 12 , wherein the selecting act further comprises:

determining the highest ranked subset of the antennas based on the received sounding feedback.

14. The method for operating a wireless transceiver of claim 12 , wherein the sounding act further comprises:

sounding the targeted transceiver with a plurality of distinct subsets of the provided antennas within each multi-tone sounding signal.

15. The method for operating a wireless transceiver of claim 12 , wherein the sounding act further comprises:

sounding the targeted transceiver with a sounding packet in which neighboring ones of the OFDM tones are spatially mapped to a plurality of distinct subsets of the provided antennas.

16. The method for operating a wireless transceiver of claim 12 , wherein the sounding act further comprises:

sounding the targeted transceiver with distinct combinations C(N,T) of chain-to-antenna couplings within each multi-tone sounding signal; where “N” is the number of antennas and “T” is the number of transmit chains.

17. The method for operating a wireless transceiver of claim 12 , wherein the sounding act further comprises:

sounding the plurality of distinct subsets of the antenna in a sounding packet; and

expanding the number of transmit chains to match the number of antennas sounded in the sounding act.

18. The method for operating a wireless transceiver of claim 12 , wherein the sounding act further comprises:

expanding the number of transmit chains to match the number of antennas; and

transmitting a sounding packet with the multi-tone sounding signal on the expanded transmit chains via the provided antennas.

19. The method for operating a wireless transceiver of claim 12 , wherein the sounding and switchable coupling acts further comprise:

combining the number “T” transmit chains provided in the second providing act into a number “N” distinct combinations each coupled to corresponding one of the number N provided antenna during the sounding act; and

switchably coupling the transmit chains to the highest ranked subset of T of the N provided antenna for transmission of data communication packets to the targeted transceiver in the transmitting act.

20. The method for operating a wireless transceiver of claim 12 , wherein the sounding act further comprises:

combining the transmit chains into distinct combinations each coupled to corresponding one of the antenna.