Inter-vehicle communication apparatus and method capable of detecting packet collision

• US 20080037577A1
• Filed: 08/09/2007
• Published: 02/14/2008
• Est. Priority Date: 08/09/2006
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Nagura, Michinaga
• Granted Patent: US 7,835,396 B2
• Time in Patent Office: Days
• US Class Current: 370/445
• CPC Class Codes: H04L 1/1657 Implicit acknowledgement of correct or incorrect reception, e.g. with a moving window
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04L 12/413 with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]
• CPC Class Codes: H04L 2012/40273 the transportation system being a vehicle

Abstract

In inter-vehicle communication, a communication apparatus may not normally receive a packet having a sufficient reception power level. Under such circumstances, a control circuit in the apparatus determines that the received packet has collided with other packet if a condition is met that a time period for a receiver circuit to receive a packet having a reception power level of equal to or more than a set value is longer than a time period required for the receiver circuit to receive a packet having a predetermined packet length.

Claims

1. A communication apparatus mounted in each vehicle and communicable with other communication apparatuses mounted in other vehicles respectively, comprising:

communication means configured to communicate with the communication apparatuses mounted in the other vehicles by wireless;

communication controlling means configured to control the communication means to enable the communication means to send out at least one packet including information to the other communication apparatuses, and to receive packets including information sent out from the other communication apparatuses; and

collision determining means configured to determine whether or not the packets sent from the other communication apparatuses and received by the communication controlling means have collided with each other.

2. The communication apparatus according to claim 1,

wherein the collision determining means is configured to determine that the packets received by the communication control means have collided with each other, when a reception time period during which the packets are received exceeds a given reception time period necessary for receiving a given packet of a predetermined bit length.

3. The communication apparatus according to claim 1,

wherein the communication controlling means is configured to control the communication means to enable the communication means to send out the at least one packet including information related to a collision of the packets, to the other communication apparatuses, when the collision determining means determines that the packets have collided with each other.

4. The communication apparatus according to claim 1,

wherein the communication controlling means is configured to control the communication means to enable the communication means to send out the at least one packet including information related to a collision of the packets, to the other communication apparatuses, when the collision determining means determines that the packets have collided with each other, the information being generated by the communication controlling means.

5. The communication apparatus according to claim 3,

wherein the communication controlling means is configured to use either a slot number that is allotted to the communication apparatus or a bit location corresponding to the slot as the information indicating the collision when the collision determining means determines that the packets have collided with each other.

6. The communication apparatus according to claim 3,

wherein the communication controlling means is configured to use a time point at which the collision occurred, as the information related to the collision, when the collision determining means determines that the packets have collided with each other.

7. The communication apparatus according to claim 3,

wherein the communication controlling means is configured to use an elapsed time as the information related to the collision, the elapsed time being a period starting from a predetermined reference time point to a time point at which the collision occurred when the collision determining means determines that the packets have collided with each other.

8. The communication apparatus according to claim 7,

wherein the predetermined reference time point is a time point of a transmission time which is included in the packets being collided.

9. The communication apparatus according to claim 1, comprising:

quantity calculating means that calculates the number of vehicles that is located surrounding a vehicle concerned; and

quantity determining means that determines whether or not the number of vehicles is equal to or more than a predetermined quantity;

wherein the communication controlling means includes means for (i) setting a random value to a transmission interval for the packets being sent in a predetermined variation range of a transmission frame, when the quantity determined means determines that the number of vehicles is less than the predetermined quantity, (ii) setting a fixed value to the transmission interval, when the quantity determining means determines that the number of vehicles is equal to or more than the predetermined quantity, and (iii) setting different values to the transmission interval, when the collision determining means determines the collision during the transmission under the fixed value which is set to the transmission interval.

10. The communication apparatus according to claim 9,

wherein the communication controlling means includes means for changing a position of the variation range in the transmission frame depending on the number of vehicles determined by the quantity determined means, and setting the transmission interval within the variation range of which the position of the range is changed.

11. The communication apparatus according to claim 1, comprising vehicle information acquisition means that acquires vehicle information indicating data of a vehicle concerned;

wherein the communication controlling means is configured add the vehicle information acquired by the vehicle information acquisition means into the packets being sent out, and control the communication means to send out the packets having the vehicle information;

the apparatus further comprising current location estimating means that estimates current locations of the vehicles whose communication apparatuses have sent out the packets to the vehicle concerned, based on the vehicle information in the received packets, when the collision determining means determines the collision.

12. The communication apparatus according to claim 1, comprising:

quantity calculating means that calculates the number of vehicles that is located surrounding a vehicle concerned; and

quantity determining means that determines whether or not the number of vehicles is equal to or more than a predetermined quantity;

wherein the communication controlling means includes means for (i) setting a variation range of transmission frame where the transmission interval for the packets being sent can vary, to avoid overlapping with a variation range of a transmission frame indicated by information embedded in the received packets, when the number of vehicles determined by the quantity determined means is less than the predetermined quantity;

(ii) setting, at random, the transmission intervals within the variation range of the transmitting frame newly set;

(iii) adding information indicating the variation range of the transmission frame into the packets being sent, and (iv) controlling the communication means to send out the packet including the information about the variation range of the transmission frame to other communication apparatuses.

13. A communication apparatus mounted in each vehicle and communicable with other communication apparatuses mounted in other vehicles respectively, comprising:

communication means that communicates with the communication apparatuses mounted in the other vehicles by wireless; and

communication controlling means that controls the communication means to allow the communication means to send out packets;

adding means that adds information indicating a transmission time into the packets being sent out, the transmission time being for transmitting the packets and decided so as to exclude the transmission time indicated by information embedded in the packets received from the other communication apparatuses, when the packets are sent out to the other communication apparatuses.

14. A communication apparatus mounted in each vehicle and communicable with other communication apparatuses mounted in other vehicles respectively, comprising:

communication means configured to communicate with the communication apparatuses mounted in the other vehicles by wireless communication; and

communication controlling means configured to (i) control the communication means to enable the communication means to send out at least one packet of information to the other communication apparatuses, and to receive packets of information sent out from the other communication apparatuses, (ii) set a transmission interval for sending the packets so as to even a distribution of transmission intervals given to a plurality of communication apparatuses, by referring information indicating transmission intervals of other communication apparatuses in received packets, (iii) add the information indicating the transmission interval into the packets being sent, and (iv) control the communication means to send out the packets to the other communication apparatuses with the transmission interval.

15. A communication apparatus mounted in each vehicle and communicable with other communication apparatuses mounted in other vehicles respectively, comprising:

communication means configured to communicate with the communication apparatuses mounted in the other vehicles by wireless communication;

communication controlling means configured to control the communication means to enable the communication means to send out at least one packet including information to the other communication apparatuses, and to receive packets including information sent out from the other communication apparatuses;

vehicle speed detecting means configured to detect a speed at which a vehicle concerned runs;

communication controlling means configured to control the communication means to send out packets, the communication controlling means including means for (i) shortening a transmission interval for sending packets as an increase in the speed of the vehicle detected by the vehicle speed detecting means, (ii) adding information indicative of a transmission interval into the packets being sent out, and (iii) controlling the communication means to send out the packets at the transmission interval to the other communication apparatuses;

approach conditions determining means configured to determine that a vehicle in the other vehicles is approaching to the vehicle concerned from behind thereof, when the transmission interval of the packet transmitted from the behind-approaching vehicle is shorter than that of the vehicle concerned; and

resetting means configured to reset the transmission interval so that the transmission interval is shortened, when the approach conditions determining means determines that the behind-approaching vehicle is approaching to the vehicle concerned.

16. The communication apparatus according to claim 15, comprising:

traffic jam determining means configured to determine whether or not the vehicle concerned is located at a rearmost position in a traffic jam catching the vehicle concerned,

wherein the communication controlling means is configured to (i) reset the transmission interval so that the transmission interval is shortened, when the approach conditions determining means determines that the behind-approaching vehicle is approaching at high speeds compared to a speed of the traffic-jammed vehicles and the traffic jam determining means determines that the vehicle concerned is located at the rearmost point of the traffic jam, and (ii) keep the current transmission interval, when the traffic jam determining means determines that the vehicle concerned is not located at the rearmost point of the traffic jam.

17. A communication method in each vehicle and communicable with other communication apparatuses mounted in other vehicles respectively, comprising steps of:

communicating with the communication apparatuses mounted in the other vehicles by wireless;

sending out at least one packet including information to the other communication apparatuses and receiving packets including information sent out from the other communication apparatuses; and

determining whether or not the packets sent from the other communication apparatuses and received by the communication controlling means have collided with each other.

18. The communication method according to claim 17, further comprising a step of:

determining that the packets received by the communication control means have collided with each other, when a reception time period during which the packets are received exceeds a given reception time period necessary for receiving a packet of a predetermined bit length.

19. The communication method according to claim 17, further comprising steps of:

adding information related to the collision into the packets being sent out, when it is determined that the packets have collided with each other; and

sending the packets including the information related to the collision to the other communication apparatuses.

20. The communication method according to claim 17, further comprising steps of:

generating information related to the collision, when it is determined that the packets have collided with each other;

inserting the information into at least one packet being sent out; and

sending the packets including the information to the other communication apparatuses.

21. A communication method in each vehicle and communicable with other communication apparatuses mounted in other vehicles respectively, comprising steps of:

communicating with the communication apparatuses mounted in the other vehicles by wireless communication;

sending out at least one packet including information to the other communication apparatuses and receiving packets including information sent out from the other communication apparatuses;

adding information indicating a transmission time into the packets being sent when the packets are sent out to the other communication apparatuses; and

controlling the transmission time for transmitting the packets at a time which is different from a transmission time indicated by the information presenting in the packets received from the other communication apparatuses.

22. A communication method in each vehicle and communicable with other communication apparatuses mounted in other vehicles respectively, comprising steps of:

communicating with the communication apparatuses mounted in the other vehicles by wireless;

sending out at least one packet including information to the other communication apparatuses and receiving packets including information sent out from the other communication apparatuses;

setting a transmission interval for sending packets so as to even a distribution of transmission intervals given to a plurality of communication apparatuses, by referring information indicating transmission interval of the other communication apparatus in received packets; and

adding information indicating the transmission interval newly set, into the packets being sent, and sending out the packet to the other communication apparatus with the transmission interval newly set.

23. A communication method in each vehicle and communicable with other communication apparatuses mounted in other vehicles respectively, comprising steps of:

communicating with the communication apparatuses mounted in the other vehicles by wireless;

sending out at least one packet including information to the other communication apparatuses and receiving packets including information sent out from the other communication apparatuses;

detecting a speed at which a vehicle concerned runs;

shortening a transmission interval for sending packets as an increase in the speed of the vehicle;

adding information of a transmission interval into the packets being sent, and sending out the packets to the other vehicles;

determining that a vehicle in the other vehicles is approaching to the vehicle concerned from behind thereof, when the transmission interval of the packet transmitted from the behind-approaching vehicle is shorter than that of the vehicle concerned; and

resetting the transmission interval so that the transmission interval is shortened, when it is determined that the behind-approaching vehicle is approaching to the vehicle concerned.

24. A communication apparatus mounted in each vehicle and communicable with other communication apparatuses mounted in other vehicles respectively, comprising:

a communication member configured to communicate with the communication apparatuses mounted in the other vehicles by wireless;

a controller having functions of;

i) controlling the communication member for sending out at least one packet including information to the other communication apparatuses and receiving packets including information sent out from the other communication apparatuses; and

ii) determining whether or not the packets sent from the other communication apparatuses and received by the communication controlling means have collided with each other.

25. The communication apparatus according to claim 24, wherein the controller has a further function of:

iii) determining the received packets have collided with each other when a reception time period during which the packets are received exceeds a given reception time period necessary for receiving a packet of a predetermined bit length.

26. The communication apparatus according to claim 24, wherein the controller has further functions of:

iv) adding information related to a collision into the packets being sent, when it is determined that the received packets have collided with each other; and

v) controlling communication member for sending the packets including the information related to the collision to the other communication apparatuses.

27. The communication apparatus according to claim 24, wherein the controller has further functions of:

vi) generating information related to the collision, when it is determined that the received packets have collided with each other;

vii) inserting the information into at least one packet being sent; and

viii) controlling communication member for sending the packets including the information to the other communication apparatuses.

28. A communication apparatus mounted in each vehicle and communicable with other communication apparatuses mounted in other vehicles respectively, comprising:

communication member configured to communicate with the communication apparatuses mounted in the other vehicles by wireless; and

controller having functions of;

i) controlling communication member for sending out at least one packet including information to the other communication apparatuses and receiving packets including information sent out from the other communication apparatuses;

ii) adding information indicating a transmission time into the packets being sent when the packets are sent out to the other communication apparatuses; and

iii) controlling the transmission time for transmitting the packets at a time which is different from a transmission time indicated by the information presenting in the packets received from the other communication apparatuses.

29. A communication apparatus mounted in each vehicle and communicable with other communication apparatuses mounted in other vehicles respectively, comprising:

communication member configured to communicate with the communication apparatuses mounted in the other vehicles by wireless; and

controller having functions of;

i) controlling communication member for sending out at least one packet including information to the other communication apparatuses and receiving packets including information sent out from the other communication apparatuses;

ii) setting a transmission interval for sending packets so as to even a distribution of transmission intervals given to a plurality of communication apparatuses, by referring information indicating transmission interval of the other communication apparatus in received packets; and

iii) adding information indicating the transmission interval newly set, into the packets being sent, and sending out the packets to the other communication apparatus with the transmission interval newly set.

30. A communication apparatus mounted in each vehicle and communicable with other communication apparatuses mounted in other vehicles respectively, comprising:

communication member configured to communicate with the communication apparatuses mounted in the other vehicles by wireless; and

controller having functions of;

i) controlling communication member for sending out at least one packet including information to the other communication apparatuses and receiving packets including information sent out from the other communication apparatuses;

ii) detecting a speed at which a vehicle concerned runs;

iii) shortening a transmission interval for sending packets as an increase in the speed of the vehicle;

iv) adding information of a transmission interval into the packets being sent, and sending out the packets to the other vehicles;

v) determining that a vehicle in the other vehicles is approaching to the vehicle concerned from behind thereof, when the transmission interval of the packet transmitted from the behind-approaching vehicle is shorter than that of the vehicle concerned; and

vi) resetting the transmission interval so that the transmission interval is shortened, when it is determined that the behind-approaching vehicle is approaching to the vehicle concerned.