Wireless performance analysis system

• US 7,516,049 B2
• Filed: 02/28/2007
• Issued: 04/07/2009
• Est. Priority Date: 02/19/2007
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Bahl, Paramvir, Chandra, Ranveer, Padhye, Jitendra D., Wolman, Alastair, Zill, Brian D.
• Primary Examiner(s): TSAI, CAROL S W
• Application Number:
  US11/680,575
• Publication Number:
  US 20080201109A1
• Time in Patent Office: 769 Days
• Field of Search: 702/186, 370/352, 370/338, 370/241, 455/411, 455/435.1, 455/426.1, 455/432, 455/432.2, 709/223, 709/225
• US Class Current: 702/186
• CPC Class Codes: H04L 41/5009 Determining service level performance parameters or violations of service level contracts, e.g. violations of agreed response time or mean time between failures [MTBF]
• CPC Class Codes: H04L 43/0829 Packet loss
• CPC Class Codes: H04L 43/0894 Packet rate
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic

Abstract

Wireless adapters are installed on one or more general purpose computing devices and are connected via a wireless network in an enterprise environment. The adapters are densely deployed at known locations throughout the environment and are configured as air monitors. The air monitors monitor wireless signals transmitted between transceiver devices and access points and records information about these signals. One or more analysis or inference engines may be deployed to analyze the signals received from the air monitors to obtain optimum performance and connectivity information about the wireless network.

Claims

1. A method comprising:

receiving, with a plurality of air monitors, wireless packets transmitted between wireless devices; and

selecting, for delivery to an application, performance information of the received wireless packets from one of the plurality of air monitors that has a highest level of confidence as determined from the received wireless packets.

2. The method as recited in claim 1 wherein the wireless packets are transmitted between an IEEE 802.11 compliant wireless transceiver and an IEEE 802.11 compliant wireless access point.

3. The method as recited in claim 1 wherein the plurality of air monitors each having a predetermined known location, and wherein the selecting from one of the plurality of air monitors is at least in part based on a location of the monitors.

4. The method as recited in claim 1 wherein the wireless packets are monitored by the plurality of air monitors over a predetermined analysis interval longer than a data submission interval.

5. The method as recited in claim 1 wherein the plurality of air monitors are connected via a wireline connection to a database, and wherein the plurality of air monitors store the performance information in the database via the wireline connection.

6. The method as recited in claim 1 wherein the one of the plurality of air monitors with the highest level of confidence is determined based on a packet count for the wireless signals received during a predetermined time period.

7. The method as recited in claim 1 further comprising selecting performance information from a second one of the plurality of air monitors having a second highest level of confidence.

8. The method as recited in claim 1 further comprising monitoring ACK packets transmitted between the wireless devices to correctly attribute a transmitter of the ACK packet.

9. The method as recited in claim 1 further comprising:

determining with an inference engine, locations of the wireless devices; and

correlating the performance information with inferred locations of the wireless devices.

10. A method comprising:

Receiving, with a plurality of air monitors, wireless packets transmitted between wireless devices; and

selecting, for delivery to an application, performance information of the received wireless packets from one of the plurality of air monitors that has a highest level of confidence, wherein the performance information is selected for delivery from a group of performance information comprising;

byte count, data frame count, data frame byte count, null frame count, null frame byte count, management frame count, management frame byte count, control frame count, control frame byte count, retry frame count, retry frame byte count, frame loss rate, number of frames transmitted at each transmission speed, number of bytes transmitted at each transmission speed.

11. A system comprising:

a first wireless device to transmit a wireless signal to a second wireless device; and

a plurality of air monitors to monitor the wireless signals transmitted between the first and second wireless devices, to store connectivity information about the transmitted wireless signal and to aggregate the stored connectivity information; and

an inference engine to determine transceiver device association states with the access point by analyzing a last packet type sent or received by the transceiver device, wherein the plurality of air monitors store connectivity information in a database, and wherein the plurality of air monitors are connected via a wireline network to the database.

12. The system as recited in claim 11 wherein the plurality of air monitors periodically transmit a wireless beacon signal to imitate an access point to induce one of the wireless devices to initiate an association process.

13. A system comprising:

a first wireless device to transmit a wireless signal to a second wireless device, wherein the first device is an IEEE 802.11 compliant wireless transceiver device and the second wireless device is an IEEE 802.11 Access Point;

a plurality of air monitors to monitor the wireless signals transmitted between the first and second wireless devices, to store connectivity information about the transmitted wireless signal and to aggregate the stored connectivity information, wherein the connectivity information is aggregated across multiple air monitors to provide more accurate information about states of the wireless transceiver device or access point; and

an inference engine to analyzes the aggregated stored connectivity information to characterizes radio frequency (RF) holes, to indicate duration of associations of the wireless transceiver devices and the access points or to indicate locations where the wireless transceiver devices cannot maintain stable associations with the access point.

14. A system comprising:

a first wireless device to transmit a wireless signal to a second wireless device, wherein the first device is an IEEE 802.11 compliant wireless transceiver device and the second wireless device is an IEEE 802.11 Access Point; and

a plurality of air monitors to monitor the wireless signals transmitted between the first and second wireless devices, to store connectivity information about the transmitted wireless signal and to aggregate the stored connectivity information, wherein the connectivity information is aggregated across multiple air monitors to provide more accurate information about states of the wireless transceiver device or access point;

wherein the air monitor monitors IEEE 802.11 compliant wireless signals, wherein the air monitors filter and store non-compliant 802.11 frames, and wherein the inference engine determines a location of the first wireless device generating the non-compliant frames and stores the determined location in a data store with the non-compliant frames.

15. A computer readable medium comprising computer-executable instructions that, when executed by one or more processors, cause the one or more processors to perform acts comprising:

receiving IEEE 802.11 compliant wireless signals transmitted between a wireless transceiver device and an access point;

storing signal performance information of the transmitted wireless signal with a plurality of air monitors, said performance information comprising;

byte count, data frame count, data frame byte count, null frame count, null frame byte count, management frame count, management frame byte count, control frame count, control frame byte count, retry frame count, retry frame byte count, frame loss rate, number of frames transmitted at each transmission speed or a number of bytes transmitted at each transmission speed; and

indicating the stored performance information stored by one of the plurality of air monitors that has a highest packet count for the wireless signals received during a predetermined time period.

16. The computer readable medium as recited in claim 15, wherein the computer-executable instructions, when executed, cause the one or more processors to perform further acts, comprising:

determining with an inference engine a location of the wireless transceiver device; and

correlating the performance information with the location.

17. A method comprising:

receiving with a plurality of air monitors, wireless packets transmitted between wireless devices;

selecting, for delivery to an application, performance information of the received wireless packets from one of the plurality of air monitors that has a highest level of confidence, wherein some of the wireless packets are a data null frame; and

detecting when a wireless transceiver switches to a different channel by monitoring a power-save mode bit within a data null frame.