Method and system for reducing sounding overhead in wireless communication

• US 10,050,693 B2
• Filed: 06/30/2016
• Issued: 08/14/2018
• Est. Priority Date: 06/30/2015
• Status: Active Grant

• Current Assignee: Rice University
• Original Assignee: Rice University
• Inventors: Bejarano, Oscar, Quadri, Sadia, Knightly, Edward W., Gurewitz, Omer, Magistretti, Eugenio
• Primary Examiner(s): Patel, Jay P
• Application Number:
  US15/199,148
• Publication Number:
  US 20170005713A1
• Time in Patent Office: 775 Days
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04W 16/28 using beam steering
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

A method for transmitting packets. The method includes making a first determination, using a first relevant sample set for a first client device, that the first client device does not need to be sounded and making a second determination, using a second relevant sample set for the second client device, that a second client device needs to be sounded. The method further includes, based on the first and second determination, performing a sounding operation for the second client device to obtain channel state information for the second client device and after performing the sounding operation for the second client device: wirelessly transmitting at least one packet to the first client device using historical channel state information for the first client device, and wirelessly transmitting at least one packet to the second client device using the channel state information.

Claims

1. A method for transmitting packets, comprising:

selecting an initial set of client devices comprising a first client device and a second client device;

making a first determination, using a first relevant sample set for the first client device, that the first client device does not need to be sounded;

making a second determination, using a second relevant sample set for the second client device, that the second client device needs to be sounded;

based on the first and second determination, performing a sounding operation for the second client device to obtain channel state information for the second client device;

after performing the sounding operation for the second client device;

wirelessly transmitting at least one packet to the first client device using historical channel state information for the first client device; and

wirelessly transmitting at least one packet to the second client device using the channel state information,

wherein making the first determination, using the first relevant sample set for the first client device, that the first client device does not need to be sounded, comprises;

determining a mean value, wherein the mean value is one selected from a group consisting of a mean phase difference and a mean magnitude difference;

determining a variance value, wherein the variance value is one selected from a group consisting of a magnitude difference variance and a phase difference variance; and

determining that the variance value is below a threshold value.

2. The method of claim 1, further comprising:

modifying, using at least the channel state information, the initial set of client devices to obtain a modified set of client devices, wherein the modified set of client devices comprises the first client device, the second client device, and a third client device, wherein the third client device was not a member of the initial set of client devices; and

wirelessly transmitting at least one packet to a third client device.

3. The method of claim 1, further comprising:

making a third determining that a third client device has experienced packet loss for a set of consecutive packets;

making a fourth determination that a sounding operation was performed for third client device prior to sending each packet in the set of consecutive packets;

based on the third determination and the fourth determination, setting a flag for the third client device; and

after setting the flag, wirelessly transmitting a packet to the third client device using a multiple-input single-output (MISO) transmission.

4. The method of claim 3, further comprising:

after setting the flag;

receiving a standard uplink transmission packet from the third client device;

removing the flag from the third client device;

after removing the flag;

selecting a second initial set of client devices comprising the third client device;

making a fifth determination, using a third relevant sample set for the third client device, that the third client device does not need to be sounded; and

based on the fifth determination, wirelessly transmitting at least one packet to the third client device using historical channel state information associated with the third client device.

5. The method of claim 1,

wherein the initial set of client devices further comprises a third client device,

the method further comprising:

making a third determination that a packet sent to the third client device was lost,

based on the third determination, performing a sounding operation for the third client device to obtain second channel state information for the third client device; and

wirelessly transmitting at least one packet to the third client device using the second channel state information.

6. The method of claim 1, wherein performing the sound operation for the second client device comprises performing the sounding operation specified in IEEE 802.11ac.

7. The method of claim 1, wherein the first client device is a mobile device.

8. The method of claim 1, wherein the first relevant sample set comprises at least one age-based sounding sample and at least one recent sounding sample.

9. The method of claim 1, wherein the relevant sample set comprises a sounding sample, wherein the sounding sample specifies at least one selected from a group consisting of a magnitude difference and a phase difference.

10. The method of claim 1, wherein the mean value is a weighted mean value and wherein the variance value is a weighted variance value.

11. An access point comprising:

a processor;

a plurality of antennas;

wherein the access point is programmed to;

select an initial set of client devices comprising a first client device and a second client device;

make a first determination, using a first relevant sample set for the first client device, that the first client device does not need to be sounded;

make a second determination, using a second relevant sample set for the second client device, that the second client device needs to be sounded;

based on the first and second determination, perform a sounding operation for the second client device to obtain channel state information for the second client device;

after performing the sounding operation for the second client device;

wirelessly transmit at least one packet to the first client device using historical channel state information for the first client device; and

wirelessly transmit at least one packet to the second client device using the channel state information, and

wherein making the first determination, using the first relevant sample set for the first client device, that the first client device does not need to be sounded, comprises;

determining a mean value, wherein the mean value is one selected from a group consisting of a mean phase difference and a mean magnitude difference;

determining a variance value, wherein the variance value is one selected from a group consisting of a magnitude difference variance and a phase difference variance; and

determining that the variance value is below a threshold value.

12. The access point of claim 11, wherein performing the sound operation for the second client device comprises performing the sounding operation specified in IEEE 802.11ac.

13. The access point of claim 11, wherein the first client device is a mobile device.

14. The access point of claim 11, wherein the first relevant sample set comprises at least one age-based sounding sample and at least one recent sounding sample.

15. The access point of claim 11, wherein the relevant sample set comprises a sounding sample, wherein the sounding sample specifies at least one selected from a group consisting of a magnitude difference and a phase difference.

16. The access point of claim 11, wherein the mean value is a weighted mean value and wherein the variance value is a weighted variance value.

17. A non-transitory computer readable medium comprising computer readable program code which, when executed by a computer processor, enables the computer processor to:

select an initial set of client devices comprising a first client device and a second client device;

make a first determination, using a first relevant sample set for the first client device, that the first client device does not need to be sounded;

make a second determination, using a second relevant sample set for the second client device, that the second client device needs to be sounded;

based on the first and second determination, perform a sounding operation for the second client device to obtain channel state information for the second client device;

after performing the sounding operation for the second client device;

wirelessly transmit at least one packet to the first client device using historical channel state information for the first client device; and

wirelessly transmit at least one packet to the second client device using the channel state information,

wherein making the first determination, using the first relevant sample set for the first client device, that the first client device does not need to be sounded, comprises;

determining a mean value, wherein the mean value is one selected from a group consisting of a mean phase difference and a mean magnitude difference;

determining a variance value, wherein the variance value is one selected from a group consisting of a magnitude difference variance and a phase difference variance; and

determining that the variance value is below a threshold value.

18. The non-transitory computer readable medium of claim 17, further comprising computer readable program code which, when executed by the computer processor, enables the computer processor to:

modify, using at least the channel state information, the initial set of client devices to obtain a modified set of client devices, wherein the modified set of client devices comprises the first client device, the second client device, and a third client device, wherein the third client device was not a member of the initial set of client devices; and

wirelessly transmit at least one packet to a third client device.