METHOD AND SYSTEM FPOR TRANSFERRING DATA TO IMPROVE RESPONSIVENESS WHEN SENDING LARGE DATA SETS

• US 20170078205A1
• Filed: 11/24/2016
• Published: 03/16/2017
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: PME IP Pty., Ltd.
• Original Assignee: PME IP Pty., Ltd.
• Inventors: STALLING, DETLEV, WESTERHOFF, MALTE
• Granted Patent: US 9,749,245 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04L 43/0894 Packet rate
• CPC Class Codes: H04L 45/121 by minimising delays
• CPC Class Codes: H04L 45/125 based on throughput or bandwidth
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/12 Avoiding congestion; Recovering from congestion
• CPC Class Codes: H04L 47/127 by using congestion prediction
• CPC Class Codes: H04L 47/27 Evaluation or update of window size, e.g. using information derived from acknowledged [ACK] packets
• CPC Class Codes: H04L 67/01 Protocols
• CPC Class Codes: H04L 69/04 Protocols for data compression, e.g. ROHC
• CPC Class Codes: H04L 69/163 In-band adaptation of TCP data exchange; In-band control procedures

Abstract

Most of the internet traffic today is carried out via the Transmission Control Protocol (TCP). The main advantage of TCP is that it provides reliable data transfer to the application layer and simplifies programming. The protocol maximizes data throughput but may also lead to noticeable transmission delay in wide area networks (WAN). A client-server based medical image viewing system is disclosed that achieves high data throughput over TCP without impacting responsiveness. Special timestamp messages inserted into the data stream allow the system to detect situations where network latency increases noticeably and to obtain a reliable estimate of sustained transfer bandwidth. The system applies a feedback scheme that avoids network delays by limiting send bandwidth. In addition other parameters, in particular image compression settings, are dynamically adjusted depending on current network quality.

Claims

1. A method comprising:

(a) determining a congestion window including;

inserting a first timestamp message into an application level request associated with a first image from a client computer;

transferring the application level request and the first timestamp message to a server;

receiving the first timestamp message at the server, where a first time is calculated based on the time the first timestamp message is received and the first timestamp message;

sending a second timestamp message from the server to the client computer;

receiving the second timestamp message at the client computer, where a second time is calculated based on the time the second timestamp message is received and the second timestamp message;

calculating an estimate of sustained bandwidth (b_est) in bytes/msec based on the first time and the second time; and

determining a congestion window based on b_est; and

(b) sending a second image before the second image is requested based on a determination of a low congestion window.

2. The method of claim 1, further comprising determining a running average of b_est based on a comparison between two or more first times and two or more second times.

3. The method of claim 2, further comprising calculating b_send, where one or more first times are used to compute b_send, where C=c_i−

c_i-1, where C is an amount of data C that was sent in a time between a last two first timestamp messages (c_i, c_i-1), and T=t_i−

t_i-1+d_i−

d_i-1 is the time elapsed on the client computer between the last two first timestamp messages, where t_i−

t_i-1 is the time elapsed on the server between the last two first timestamp messages, and d_i and d_i-1 are differences between client computer time and server time when one or more first time stamp messages arrived at the server; and

determining the congestion window based on one or both of b_est and b_send.

4. The method of claim 3, further comprising calculating b_read, where one or more second times are used to compute b_read, where C=c_i−

c_i-1, where C is an amount of data C that was read in a time between a last two second timestamp messages (c_i, c_i-1), and T=t_i−

t_i-1+d_i−

d_i-1 is the time elapsed on the client computer between the last two second timestamp messages, where t_i−

t_i-1 is the time elapsed on the server between the last two second timestamp messages, and d_i and d_i-1 are differences between client computer time and server time when one or more second time stamp messages arrived at the client computer; and

determining the congestion window based on one or both of b_est and b_read.

5. The method of claim 4, further comprising determining the congestion window based on one or more of b_send, b_read and b_est.

6. The method of claim 5, where b_read is used as b_est when b_send is greater than thirty (30) percent of b_read.

7. The method of claim 5, where b_read samples are included into the running average when b_read is more than approximately forty (40) percent of b_est.

8. The method of claim 2, where a bandwidth limit (b_limit) is applied on the server in order to avoid network delays, where b_limit is computed using a feedback scheme.

9. The method of claim 8, where the feedback scheme uses a pseudo code.

10. The method of claim 9, where the pseudo code includes an expression

11. The method of claim 10, where b_limit is used to compute a lossy compression rate.

12. The method of claim 11, where the lossy compression rate is calculated in order to achieve a desired interactive speed.

13. The method of claim 12, where the lossy compression rate is used to stream compressed images with a compression ratio.

14. The method of claim 13, where images are streamed to the client computer using a buffering system.

15. The method of claim 14, where the buffering system is based on monitoring user interaction and anticipating a next image that will be requested by the client computer.

16. The method of claim 15, where b_limit is used to compute the lossy compression rate.

17. The method of claim 16, where the lossy compression rate is calculated in order to achieve a desired interactive speed.

18. The method of claim 17, where the lossy compression rate is used to calculate a compression ratio, where one or more compressed images are streamed with the compression ratio.

19. The method of claim 17, where a target compression quality is defined by a user, where a first image is streamed with a first compression quality, where the first compression quality minimizes network latency during interaction based on bandwidth monitoring and where the first image is streamed with a second compression quality when the user stops interacting, where the second compression quality is greater than the first compression quality if the first compression quality is lower than a target compression quality.

20. A method comprising:

determining a congestion window including;

sending a request for a first image from a client computer to a server, including inserting a first timestamp message into the request for a first image at an application level;

receiving the first timestamp message at the server;

sending a second timestamp message from the server to the client computer, including inserting a second timestamp into the second timestamp message;

calculating a first time for the first timestamp message to be sent from the client computer to the server and a second time for the second timestamp message to be sent from the server to the client computer; and

calculating the congestion window based on the first time and the second time; and

sending a second image before the second image is requested based on a low congestion window.