COMMUNICATION APPARATUS AND METHOD OF CALCULATING ROUND TRIP TIME

• US 20090323543A1
• Filed: 06/18/2009
• Published: 12/31/2009
• Est. Priority Date: 06/30/2008
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Shimakura, Masami
• Granted Patent: US 7,889,672 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04L 43/0864 Round trip delays

Abstract

A communication apparatus which transmits data to a transmission destination, and receives, from the transmission destination, an acknowledgement indicating that the data has been received stores, in a memory, first specific data for specifying a plurality of transmission data, and transmission time data indicating transmission times of the plurality of transmission data. Based on second specific data contained in the acknowledgement, the communication apparatus searches the memory for first specific data for specifying transmission data corresponding to the acknowledgement, and calculates a round trip time based on the transmission time of the transmission data specified by the found first specific data, and a reception time at which the acknowledgement is received.

Claims

1. A communication apparatus which transmits data to a transmission destination, and receives, from the transmission destination, an acknowledgement indicating that the data has been received, comprising:

a memory unit configured to store first specific data for specifying a plurality of transmission data, and transmission time data indicating transmission times of the plurality of transmission data;

a search unit that searches, based on second specific data contained in the acknowledgement, said memory unit for first specific data for specifying transmission data corresponding to the acknowledgement; and

a unit that calculates a round trip time based on a transmission time of the transmission data specified by the first specific data found by said search unit, and a reception time at which the acknowledgement is received.

2. The apparatus according to claim 1, wherein the first specific data indicates start data and end data of the transmission data, and said search unit performs, based on the second specific data, a range search within a range between the start data and the end data indicated by the first specific data.

3. The apparatus according to claim 1, wherein every time data is transmitted, said memory unit stores first specific data for specifying the transmitted data, and transmission time data indicating a transmission time.

4. A method of calculating a round trip time in a communication apparatus which transmits data to a transmission destination, and receives, from the transmission destination, an acknowledgement indicating that the data has been received, the method comprising:

storing, in a memory, first specific data for specifying a plurality of transmission data, and transmission time data indicating transmission times of the plurality of transmission data;

searching, based on second specific data contained in the acknowledgement, the memory for first specific data for specifying transmission data corresponding to the acknowledgement; and

calculating a round trip time based on a transmission time of the transmission data specified by the found first specific data, and a reception time at which the acknowledgement is received.

5. The method according to claim 4, wherein the first specific data indicates start data and end data of the transmission data, and a range search within a range between the start data and the end data indicated by the first specific data is performed based on the second specific data.

6. The method according to claim 4, wherein every time data is transmitted, first specific data for specifying the transmitted data, and transmission time data indicating a transmission time are stored in the memory.

7. A storage medium storing a computer program for transmitting data to a transmission destination, receiving, from the transmission destination, an acknowledgement indicating that the data has been received, and calculating a round trip time, the program comprising:

a code for storing, in a memory, first specific data for specifying a plurality of transmission data, and transmission time data indicating transmission times of the plurality of transmission data;

a code for searching, based on second specific data contained in the acknowledgement, the memory for first specific data for specifying transmission data corresponding to the acknowledgement; and

a code for calculating a round trip time based on a transmission time of the transmission data specified by the found first specific data, and a reception time at which the acknowledgement is received.