Establishing fairness and reducing delay in broadcast based vehicle to vehicle communication using application-level phase adjustments

• US 9,210,722 B2
• Filed: 10/05/2012
• Issued: 12/08/2015
• Est. Priority Date: 10/12/2011
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Batsuuri, Tseesuren, Lukkien, Johannes Jan, Bril, Reinder Jaap
• Primary Examiner(s): Faroul, Farah
• Application Number:
  US13/645,537
• Publication Number:
  US 20130094493A1
• Time in Patent Office: 1,159 Days
• Field of Search: 370/347
• US Class Current: 1/1
• CPC Class Codes: H04B 7/204 Multiple access
• CPC Class Codes: H04B 7/212 Time-division multiple access [TDMA]
• CPC Class Codes: H04W 74/0816 with collision avoidance

Abstract

A method for a station to periodically broadcast messages over a wireless channel to communicate to multiple other stations who transmit on the same channel, the station becomes ready to broadcast at successive message activation times, at a message activation time the station performing a Multiple Access mechanism (930) to resolve channel access competition and the station subsequently starting transmission of a message, wherein at least two successive message activation times differ a random time interval.

Claims

1. A method for a station to periodically broadcast messages over a wireless channel to communicate to multiple other stations who transmit on an identical wireless channel, the method comprising:

selecting a message activation time;

performing, with the station, a Multiple Access mechanism to resolve channel access competition with the multiple other stations; and

transmitting, with the station, at least a first message and a second message, wherein successive message activation times between the first message and the second message differ by a random time interval.

2. The method as in claim 1, further comprising:

employing a Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) mechanism at each message activation time.

3. The method as in claim 1, further comprising:

checking, at each message activation time, whether the wireless channel is busy during an Arbitration Inter Frame Space (AIFS); and

when the wireless channel is busy, waiting for the wireless channel to become idle.

4. The method as in claim 3, further comprising:

selecting an increasing Contention Window (CW); and

waiting for a random Back-off (Bf) period based on the selected Contention Window (CW).

5. The method as in claim 1, wherein successive message activation times differ, on average, by a broadcast period.

6. The method as in claim 1, further comprising:

changing a phase of the periodically broadcast messages.

7. The method as in claim 6, wherein the random time interval is between zero and twice a broadcast period.

8. The method as in claim 1, wherein successive message activation times differ by a random time interval.

9. The method as in claim 1, further comprising:

configuring the station with an elastic rate, wherein two successive message activation times differ by a random time interval.

10. The method as in claim 1, wherein the station is configured with an activation jitter, successive message activation times differ by a broadcast period plus a random value, and the random value is the activation jitter minus a random number between zero and twice the activation jitter.

11. The method as in claim 10, wherein each message has a message transmission time, and the activation jitter is at least twice the message transmission time.

12. The method of claim 11, wherein the activation jitter is at least twenty times the message transmission time.

13. The method of claim 11, wherein the activation jitter is less than the broadcast period.

14. The method of claim 13, wherein the activation jitter is less than 10% of the broadcast period.

15. The method as in claim 1, wherein the station is configured with an elastic rate and an activation jitter, successive message activation times differ by a broadcast period plus a random value.

16. The method of claim 15, wherein two successive message activation times differ by a random time interval after a number of message activation times have passed.

17. The method as in claim 1, wherein the station and the multiple other stations are each disposed in different vehicles.

18. A non-transitory computer-readable storage medium comprising a computer program which causes a computer to perform the method of claim 1 when the computer program is run on the computer.

19. A station configured to periodically broadcast messages over a wireless channel and communicate to multiple other stations which transmit on the same channel, the station comprising:

a message activation time selector that is configured to select a message activation time, wherein the station is further configured to perform a Multiple Access mechanism to resolve channel access competition with the multiple other stations and transmit at least a first message and a second message wherein successive message activation times between the first message and the second message differ by a random time interval.

20. The station of claim 19, further comprising:

a counter, wherein the counter is incremented each time each message activation time is reached.