Communication apparatus, communication system, and communication method

• US 8,626,869 B2
• Filed: 07/10/2009
• Issued: 01/07/2014
• Est. Priority Date: 07/10/2008
• Status: Active Grant

• Current Assignee: Nagoya University, Autonetworks Technologies, Ltd. (Sumitomo Corporation), Sumitomo Electric Industries Limited (Sumitomo Corporation), Sumitomo Wiring Systems Limited (Sumitomo Corporation)
• Original Assignee: Nagoya University, Autonetworks Technologies, Ltd. (Sumitomo Corporation), Sumitomo Electric Industries Limited (Sumitomo Corporation), Sumitomo Wiring Systems Limited (Sumitomo Corporation)
• Inventors: Takada, Hiroaki, Kurachi, Ryo, Miyashita, Yukihiro
• Primary Examiner(s): Moore, Ian N
• Assistant Examiner(s): La, Phong
• Application Number:
  US12/990,732
• Publication Number:
  US 20110047244A1
• Time in Patent Office: 1,642 Days
• Field of Search: 370/313, 370/467, 370/536, 370/533, 370/532, 370/512, 370/492, 370/505, 370/504, 370/501, 370/503, 370/509, 709/217, 709/207, 709/29, 709/32, 709/33, 455/432, 455/345
• US Class Current: 709/217
• CPC Class Codes: H04L 12/4135 using bit-wise arbitration
• CPC Class Codes: H04L 12/44 Star or tree networks

Abstract

When sending data, an ECU sends time lag information indicating a time lag that is a difference between time of generating time point at which the data is generated and time of sending start time point at which the ECU actually starts sending the data. When transferring the data, a relay apparatus adds time lag information indicating a time lag that is a difference between time of receiving start time point at which the relay apparatus starts receiving the data and time of transferring start time point at which the relay apparatus starts transferring the data, onto the time lag added on the received data. When receiving the data, an ECU determines for the received data the time of the generating time point that is earlier the time lag indicated by the time lag information of the received data than the time at which the ECU starts receiving the data.

Claims

1. A communication apparatus having a clock unit, and a communication unit for sending and receiving data, comprising:

a data generating unit that generates a first data;

a generation obtaining unit that obtains a generating time point based on the clock unit and corresponding to the time that the first data is generated;

a sending obtaining unit that obtains a sending start time point based on the clock unit and corresponding to the time that the communication unit starts to externally send the first data;

a calculation unit that calculates a time lag between the generating time point and the sending start time point;

an addition unit that adds time lag information onto the first data, the time lag information indicating the time lag calculated by the calculation unit;

a reception determination unit that determines a receiving start time point based on the clock unit and corresponding to the time that the communication unit externally receives a second data;

an extraction unit that extracts added time lag information from the second data; and

a generation determination unit that determines a data generating time point of the second data based on the added time lag information and the receiving start time point, wherein

the communication unit externally sends the first data onto which the time lag information has been added by the addition unit.

2. The communication apparatus according to claim 1, further comprising:

a send time determination unit that determines, based on the clock unit, whether the sending start time point has elapsed, wherein

when the send time determination unit determines that the sending start time point has elapsed,

the sending obtaining unit obtains a new sending start time point,

the calculation unit recalculates the time lag,

the addition unit updates the time lag information added onto the first data, and

the communication unit resends the first data onto which the time lag information has been added by the addition unit.

3. The communication apparatus according to claim 2, further comprising:

a transfer obtaining unit that obtains a transferring start time point based on the clock unit and corresponding to the time that the communication unit starts to externally send the second data; and

a second calculation unit calculates a second time lag between the generating time point of the second data and the transferring start time point, wherein

the addition unit adds second time lag information onto to the second data, the second time lag information indicating the second time lag calculated by the second calculation unit, and

the communication unit sends the second data onto which the second time lag information has been added by the addition unit to another communication apparatus.

4. The communication apparatus according to claim 1, further comprising:

a transfer obtaining unit that obtains a transferring start time point based on the clock unit and corresponding to the time that the communication unit starts to externally send the second data; and

a second calculation unit calculates a second time lag between the generating time point of the second data and the transferring start time point, wherein

the addition unit adds second time lag information onto to the second data, the second time lag information indicating the second time lag calculated by the second calculation unit, and

the communication unit sends the second data onto which the second time lag information has been added by the addition unit to another communication apparatus.

5. A communication system comprising a plurality of communication apparatuses, each communication apparatus having a clock unit, and a communication unit for sending and receiving data, wherein each communication apparatus comprises:

a data generating unit that generates a first data;

a generation obtaining unit that obtains a generating time point based on the clock unit and corresponding to the time that the first data is generated;

a sending obtaining unit that obtains a sending start time point based on the clock unit and corresponding to the time that the communication unit starts to externally send data;

a calculation unit that calculates a time lag between the generating time point and the sending start time point;

an addition unit that adds time lag information onto the first data, the time lag information indicating the time lag calculated by the calculation unit;

a reception determination unit that determines a receiving start time point based on the clock unit and corresponding to the time that the communication unit externally receives a second data;

an extraction unit that extracts added time lag information from the second data; and

a generation determination unit that determines a data generating time point of the second data based on the added time lag information and the receiving start time point, wherein

the communication unit externally sends the first data onto which the time lag information has been added by the addition unit.

6. A method performed by a communication apparatus having a clock unit, and a communication unit for sending and receiving data, the method comprising:

generating a first data;

obtaining a generating time point based on the clock unit and corresponding to the time that the first data is generated;

obtaining a sending start time point based on the clock unit and corresponding to the time that data is sent;

calculating a time lag between the generating time point and the sending start time point;

adding time lag information onto the first data, the time lag information indicting the time lag;

determining a receiving start time point based on the clock unit and corresponding to the time that a second data is received;

extracting added time lag information from the second data;

determining a data generating time point of the second data based on the added time lag information and the receiving start time point; and

sending the first data onto which the time lag information has been added.

7. A method performed by a communication apparatus having a clock unit, and a communication unit for sending and receiving data, the method comprising:

determining a sending start time point to send a data;

calculating a time lag between time of the sending start time point and a generating time point at which the data is generated;

adding time lag information onto the data, the time lag information indicating the time lag;

deciding whether the sending start time point has elapsed;

sending the data onto which the time lag information has been added when it is decided that the sending start time point has elapsed; and

when it determined that the sending start time point has elapsed;

obtaining a new sending start time point;

recalculating the time lag based on the new sending start time point and the generating time point at which the data is generated;

updating the time lag information added onto the data, and

resending the data onto which the time lag information has been added.