Triggering and transmitting sounding packets for wireless communications
View Patent ↗A process for determining when sounding packets are to be triggered and transmitted in a wireless beamforming system is disclosed. In one embodiment, a timer is programmably set to adapt to the operating environment. Whenever the timer elapses, a sounding packet is triggered and the timer resets. In another embodiment, the sounding packet is triggered by comparing measured correlations of channel characteristics against a programmable correlation threshold. If a measured correlation falls below the correlation threshold, this indicates that the channel has undergone a relatively large change. In response, a new sounding packet is triggered to update the beam steering matrix. Otherwise, the previous beam steering matrix is still used. Thereby, sounding packets are expeditiously triggered to keep the beam steering matrix updated with minimal impact to the over-the-air bandwidth.
1. In a wireless communications device, a method for determining when sounding packets are to be transmitted, comprising:
setting a correlation threshold;
processing at least two channel estimations to determine two corresponding channel characteristics;
measuring a correlation between the two channel characteristics to obtain a measured correlation;
determining whether the measured correlation is less than the correlation threshold; and
transmitting a sounding packet to update a beamforming matrix if the measured correlation is less than the correlation threshold,
wherein the two channel estimations correspond to a channel state information/beamforming matrix/compressed beamforming matrix (CSI/V/CV) feedback packet and to an acknowledge (ACK) packet.
2. The method of claim 1 , wherein the wireless communications device operates in an explicit beamforming mode.
3. In a wireless communications device, a method for determining when sounding packets are to be transmitted, comprising:
setting a correlation threshold;
processing at least two channel estimations to determine two corresponding channel characteristics;
measuring a correlation between the two channel characteristics to obtain a measured correlation;
determining whether the measured correlation is less than the correlation threshold; and
transmitting a sounding packet to update a beamforming matrix if the measured correlation is less than the correlation threshold,
wherein the two channel estimations correspond to two acknowledge (ACK) packets.
4. The method of claim 3 , wherein the wireless communications device operates in an explicit beamforming mode.
5. The method of claim 3 , wherein the wireless communications device operates in an implicit beamforming mode.
6. In a wireless communications device, a method for determining when sounding packets are to be transmitted, comprising:
setting a correlation threshold;
processing at least two channel estimations to determine two corresponding channel characteristics;
measuring a correlation between the two channel characteristics to obtain a measured correlation;
determining whether the measured correlation is less than the correlation threshold; and
transmitting a sounding packet to update a beamforming matrix if the measured correlation is less than the correlation threshold,
wherein the two channel estimations correspond to an acknowledge (ACK) packet and a sounding packet.
7. The method of claim 6 , wherein the wireless communications device operates in an implicit beamforming mode.
8. The method of claim 1 , wherein the measured correlation is obtained by directly calculating the correlation between the two channel characteristics.
9. The method of claim 1 , wherein the measured correlation is obtained by comparing frequency response profiles of the two channels.
10. The method of claim 1 , wherein the measured correlation is obtained by comparing bin weighting values of the two channels.
11. The method of claim 1 , wherein the measured correlation is obtained by comparing two differential sequences, each corresponding to one channel characteristic.
12. A wireless device comprising:
a plurality of antennas for transmitting a wireless signal;
a beamforming circuit coupled to the antennas for weighting and combining raw data signals;
a control circuit coupled to the beamforming circuit that determines when to trigger a sounding packet;
a memory coupled to a processor that stores a programmable correlation threshold; and
a correlator coupled to the processor that correlates measured channel characteristics,
wherein the sounding packet is triggered by comparing a correlation of the measured channel characteristics to the programmable correlation threshold, and
wherein the measured channel characteristics comprise a channel estimation corresponding to a channel state information/beamforming matrix/compressed beamforming matrix (CSI/C/CV) packet and a channel estimation corresponding to an acknowledge (ACK) packet.
13. The wireless device of claim 12 , wherein the wireless device comprises an explicit beamforming system.
14. A wireless device comprising:
a plurality of antennas for transmitting a wireless signal;
a beamforming circuit coupled to the antennas for weighting and combining raw data signals;
a control circuit coupled to the beamforming circuit that determines when to trigger a sounding packet;
a memory coupled to a processor that stores a programmable correlation threshold; and
a correlator coupled to the processor that correlates measured channel characteristics,
wherein the sounding packet is triggered by comparing a correlation of the measured channel characteristics to the programmable correlation threshold, and
wherein the measured channel characteristics correspond to channel estimations of two acknowledge (ACK) packets.
15. The wireless device of claim 14 , wherein the wireless device comprises an explicit beamforming system.
16. The wireless device of claim 14 , wherein the wireless device comprises an implicit beamforming system.
17. A wireless device comprising:
a plurality of antennas for transmitting a wireless signal;
a beamforming circuit coupled to the antennas for weighting and combining raw data signals;
a control circuit coupled to the beamforming circuit that determines when to trigger a sounding packet;
a memory coupled to a processor that stores a programmable correlation threshold; and
a correlator coupled to the processor that correlates measured channel characteristics,
wherein the sounding packet is triggered by comparing a correlation of the measured channel characteristics to the programmable correlation threshold, and
wherein the measured channel characteristics comprise a channel estimation corresponding to an acknowledge (ACK) packet and a channel estimation corresponding to the sounding packet.
18. The wireless device of claim 17 , wherein the wireless device comprises an implicit beamforming system.
19. A wireless device comprising:
a plurality of antennas for transmitting a wireless signal;
a beamforming circuit coupled to the antennas for weighting and combining raw data signals;
a control circuit coupled to the beamforming circuit that determines when to trigger a sounding packet;
a memory coupled to a processor that stores a programmable correlation threshold; and
a correlator coupled to the processor that correlates measured channel characteristics,
wherein the sounding packet is triggered by comparing a correlation of the measured channel characteristics to the programmable correlation threshold, and
wherein the correlation of the measured channel characteristics is obtained by comparing frequency response profiles of two channels.
20. A wireless device comprising:
a plurality of antennas for transmitting a wireless signal;
a beamforming circuit coupled to the antennas for weighting and combining raw data signals;
a control circuit coupled to the beamforming circuit that determines when to trigger a sounding packet;
a memory coupled to a processor that stores a programmable correlation threshold; and
a correlator coupled to the processor that correlates measured channel characteristics,
wherein the sounding packet is triggered by comparing a correlation of the measured channel characteristics to the programmable correlation threshold, and
wherein the correlation of the measured channel characteristics is obtained by comparing bin weighting values of two channels.
21. A wireless device comprising:
a plurality of antennas for transmitting a wireless signal;
a beamforming circuit coupled to the antennas for weighting and combining raw data signals;
a control circuit coupled to the beamforming circuit that determines when to trigger a sounding packet;
a memory coupled to a processor that stores a programmable correlation threshold; and
a correlator coupled to the processor that correlates measured channel characteristics,
wherein the sounding packet is triggered by comparing a correlation of the measured channel characteristics to the programmable correlation threshold, and
wherein the correlation of the measured channel characteristics is obtained by comparing two differential sequences, each corresponding to one channel characteristic.
22. The method of claim 3 , wherein the measured correlation is obtained by directly calculating the correlation between the two channel characteristics.
23. The method of claim 3 , wherein the measured correlation is obtained by comparing frequency response profiles of the two channels.
24. The method of claim 3 , wherein the measured correlation is obtained by comparing bin weighting values of the two channels.
25. The method of claim 3 , wherein the measured correlation is obtained by comparing two differential sequences, each corresponding to one channel characteristic.
26. The method of claim 6 , wherein the measured correlation is obtained by directly calculating the correlation between the two channel characteristics.
27. The method of claim 6 , wherein the measured correlation is obtained by comparing frequency response profiles of the two channels.
28. The method of claim 6 , wherein the measured correlation is obtained by comparing bin weighting values of the two channels.
29. The method of claim 6 , wherein the measured correlation is obtained by comparing two differential sequences, each corresponding to one channel characteristic.