Beamforming training in orthogonal frequency division multiple access (OFDMA) communication systems
A beamforming training packet is transmitted from a first communication device to multiple second communication devices. A trigger frame is generated at the first communication device to trigger an uplink orthogonal frequency division multiple access (OFDMA) transmission of beamforming training feedback from at least some of the multiple second communication devices. After transmission of the beamforming training packet by the first communication device, the trigger frame is transmitted to the at least some of the multiple communication devices. The uplink OFDMA transmission is then received at the first communication device. The uplink OFDMA transmission includes respective beamforming training feedback packets generated based on the beamforming training packet by respective ones of the at least some of the multiple second communication devices. The respective beamforming training feedback packets are simultaneously transmitted by the at least some of the multiple second communication devices.
1. A method for beamforming training in a wireless communication network, the method comprising:
transmitting, from a first communication device, a transmission to multiple second communication devices, wherein the transmission indicates that the first communication device will subsequently transmit a null data packet (NDP), wherein the multiple second communication devices include i) a plurality of non-legacy second communication devices and ii) a legacy second communication device, wherein the transmission includes an NDP announcement frame that includes multiple per-station information fields for indicating respective second communication devices that are to provide feedback in response to the NDP, wherein the multiple per-station information fields are arranged in an order, wherein a first-occurring per-station information field in the order is set to indicate an address that has not been allocated to any communication devices in the wireless communication network, and wherein another per-station information field after the first-occurring per-station information field is set to indicate an address of the legacy second communication device;
transmitting, from the first communication device, the NDP;
generating, at the first communication device, a trigger frame to trigger an uplink orthogonal frequency division multiple access (OFDMA) transmission of beamforming training feedback from at least some non-legacy second communication devices among the plurality of non-legacy second communication devices;
transmitting, with the first communication device and after transmission of the NDP by the first communication device, the trigger frame to the at least some non-legacy second communication devices among the plurality of non-legacy second communication devices;
receiving, at the first communication device, the uplink OFDMA transmission, wherein the uplink OFDMA transmission includes respective beamforming training feedback packets generated based on the NDP by respective ones of the at least some non-legacy second communication devices among the plurality of non-legacy second communication devices, and wherein the respective beamforming training feedback packets are simultaneously transmitted by the at least some non-legacy second communication devices among the plurality of non-legacy second communication devices; and
after receiving the uplink OFDMA transmission, transmitting a polling frame to trigger transmission of beamforming training feedback, corresponding to the NDP, from the legacy second communication device.
2. The method of claim 1 , wherein transmitting the trigger frame comprises transmitting the trigger frame upon expiration of a first predetermined time interval after transmission of the NDP.
3. The method of claim 2 , wherein the first predetermined time interval corresponds to a short inter-frame spacing (SIFS) time interval.
4. The method of claim 1 , wherein the trigger frame causes the at least some non-legacy second communication devices among the plurality of non-legacy second communication devices to transmit the respective beamforming training feedback packets upon expiration of a second predetermined time interval after reception of the trigger frame by the at least some non-legacy second communication devices among the plurality of non-legacy second communication devices.
5. The method of claim 4 , wherein the second predetermined time interval corresponds to a short inter-frame spacing (SIFS) time interval.
6. The method of claim 1 , wherein
the trigger frame includes subchannel allocation information corresponding to the at least some non-legacy second communication devices among the plurality of non-legacy second communication devices, and
the respective beamforming training feedback packets simultaneously transmitted by the at least some non-legacy second communication devices among the plurality of non-legacy second communication devices are transmitted in respective frequency portions in accordance with the subchannel allocation information.
7. The method of claim 1 , wherein the NDP announcement frame occupies an entire bandwidth of a communication channel.
8. The method of claim 1 , wherein the NDP announcement frame is duplicated in each of a plurality of subchannels of a communication channel.
9. An apparatus, comprising:
a network interface device implemented on one or more integrated circuits;
wherein the one or more integrated circuits are configured to:
transmit a transmission to multiple communication devices, wherein the transmission indicates that the network interface device will subsequently transmit a null data packet (NDP), wherein the multiple communication devices include i) a plurality of non-legacy communication devices and ii) a legacy communication device, wherein the transmission includes an NDP announcement frame that includes multiple per-station information fields for indicating respective second communication devices that are to provide feedback in response to the NDP, wherein the multiple per-station information fields are arranged in an order, wherein a first-occurring per-station information field in the order is set to indicate an address that has not been allocated to any communication devices in the wireless communication network, and wherein another per-station information field after the first-occurring per-station information field is set to indicate an address of the legacy communication device
transmit the NDP;
generate a trigger frame to trigger an uplink orthogonal frequency division multiple access (OFDMA) transmission of beamforming training feedback from at least some non-legacy communication devices among the plurality of non-legacy communication devices;
after transmission of the NDP, transmit the trigger frame to the at least some non-legacy communication devices among the plurality of non-legacy communication devices;
receive the uplink OFDMA transmission, wherein the uplink OFDMA transmission includes respective beamforming training feedback packets generated based on the NDP by respective ones of the at least some non-legacy communication devices among the plurality of non-legacy communication devices, and wherein the respective beamforming training feedback packets are simultaneously transmitted by the at least some non-legacy communication devices among the plurality of non-legacy communication devices; and
after receiving the uplink OFDMA transmission, transmit a polling frame to trigger transmission of beamforming training feedback, corresponding to the NDP, from the legacy communication device.
10. The apparatus of claim 9 , wherein the one or more integrated circuits are configured to transmit the trigger frame upon expiration of a first predetermined time interval after transmission of the NDP.
11. The apparatus of claim 10 , wherein the first predetermined time interval corresponds to a short inter-frame spacing (SIFS) time interval.
12. The apparatus of claim 9 , wherein the trigger frame causes the at least some non-legacy communication devices among the plurality of non-legacy communication devices to transmit the respective beamforming training feedback packets upon expiration of a second predetermined time interval after reception of the trigger frame by the at least some non-legacy communication devices among the plurality of non-legacy communication devices.
13. The apparatus of claim 12 , wherein the second predetermined time interval corresponds to a short inter-frame spacing (SIFS) time interval.
14. The apparatus of claim 9 , wherein
the trigger frame includes subchannel allocation information corresponding to the at least some non-legacy communication devices among the plurality of non-legacy communication devices, and
the respective beamforming training feedback packets simultaneously transmitted by the at least some of the plurality of non-legacy communication devices are transmitted in respective frequency portions in accordance with the subchannel allocation information.
15. The apparatus of claim 9 , wherein the NDP announcement frame occupies an entire bandwidth of a communication channel.
16. The apparatus of claim 9 , wherein the NDP announcement frame is duplicated in each of a plurality of subchannels of a communication channel.