Estimating Communication Conditions

• US 20110149751A1
• Filed: 12/21/2009
• Published: 06/23/2011
• Est. Priority Date: 12/21/2009
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Jain, Manish, Li, Jin, Shieh, Guo-Wei, Khan, Humayun Mukhtar
• Granted Patent: US 8,441,930 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04L 41/147 for predicting network behaviour
• CPC Class Codes: H04L 43/0882 Utilisation of link capacity
• CPC Class Codes: H04L 43/12 Network monitoring probes

Abstract

Embodiments are configured to provide communication features, including providing channel condition estimates for a communication path, such as packet loss, jitter, and/or available bandwidth, but are not so limited. In an embodiment, a method uses aspects of in-band data packets to provide channel condition estimates. In one embodiment, a system includes a bandwidth estimation component that operates to classify payload packets as part of performing capacity estimation and available bandwidth estimation operations.

Claims

1. A system comprising:

a communication path for communicating information including packets,

a bandwidth estimator to provide an estimate of an amount of available bandwidth associated with the communication path based in part on an assessment of payload packet parameters of the packets communicated over the communication path, the bandwidth estimator operable to;

determine a first packet gap for the packets transmitted over the communication path;

determine a second packet gap for the packets received over the communication path;

determine a path capacity estimate based in part on a packet length divided by the difference of the received packet gap and the transmitted packet gap for packets that do not experience a defined amount of congestion; and

,

determine the capacity and the amount of available bandwidth based on the packets that do experience the defined amount of congestion; and

,

memory to store the estimate of the amount of available bandwidth.

2. The system of claim 1, the bandwidth estimator further operable to determine the path capacity estimate based in part on a tight link capacity estimate.

3. The system of claim 2, the bandwidth estimator further operable to determine the path capacity estimate using a histogram and a number of previously calculated link capacity estimates.

4. The system of claim 2, the bandwidth estimator further operable to determine the path capacity estimate by using a peak occurrence of a capacity histogram.

5. The system of claim 4, the bandwidth estimator further operable to determine the estimate of the amount of available bandwidth using a regression model.

6. The system of claim 4, the bandwidth estimator further operable to determine the estimate of the amount of available bandwidth and capacity of the tight link jointly using a linear regression method.

7. The system of claim 1, the bandwidth estimator further operable to determine the link capacity estimate if a received packet gap value is larger than a transmitted packet gap value.

8. The system of claim 1, the bandwidth estimator further operable to classify received probe packets using packet classes based in part on congested and uncongested network conditions.

9. The system of claim 8, the bandwidth estimator further operable to classify received probe packets in a first packet class corresponding to congested packets and a second packet class corresponding to uncongested packets.

10. The system of claim 8, the bandwidth estimator further operable to use packet parameters of a first packet class to calculate capacity of the path and packet parameters of a second packet class to calculate available bandwidth estimates and capacity estimates of a tight link.

11. A method of communicating comprising:

receiving a number of payload packets over an end-to-end communication path, wherein the end-to-end communication path includes a number of cross-traffic packets;

receiving delivery information of the payload packets;

estimating a sending timestamp of each payload packet;

obtaining a receiving timestamp of each payload packet; and

,

estimating network channel characteristics based in part on the delivery information, and the sending and receiving timestamps of the payload packets.

12. The method of communicating of claim 11 further comprising estimating the sending timestamp of each payload packet based in part on a pre-determined schedule.

13. The method of communicating of claim 11 further comprising calculating a packet loss characteristic of the path based in part on the delivery information.

14. The method of communicating of claim 13 further comprising synchronizing the sending and a receiving clock by using a set of non-congested packets and calculating a clock drift parameter using a linear regression model and the set of non-congested packets.

15. The method of communicating of claim 14 further comprising calculating a jitter characteristic of the path based in part on synchronized sending and receiving timestamps.

16. The method of communicating of claim 11 further comprising calculating a jitter characteristic of the path based in part on a self-synchronized jitter calculation that includes using sending gap and receiving gap parameters.

17. The method of communicating of claim 11, further comprising:

calculating the available bandwidth of the path by;

classifying a first set of packets, wherein the first set of packets are associated with a first communication time over the path;

classifying a second set of packets, wherein the second set of packets are associated with a second communication time over the path;

providing a capacity estimate based in part on the first set of packets and a capacity estimate histogram; and

,

providing a bandwidth estimate based in part on the second set of packets and the capacity estimate histogram; and

,

storing the bandwidth estimate in memory.

18. A communication device comprising:

a transmitter to transmit communications that include packets of information over a communication path;

a receiver to receive communicated packets over the communication path, the communicated packets having received packet gaps, wherein the communicated packets have corresponding origination packet gaps;

a bandwidth estimator to calculate a path capacity estimate for the communication path based in part on calculated link capacity estimates and a congestion threshold using select pairs of communicated packets, and to calculate a bandwidth estimate based in part on the path capacity estimate and a bandwidth estimation model; and

memory to store the bandwidth estimate.

19. The device of claim 18, wherein the bandwidth estimator operates to correct for clock drift.

20. The device of claim 18, wherein the bandwidth estimator operates to calculate jitter characteristics of a network.