ESTABLISHING FAIRNESS AND REDUCING DELAY IN BROADCAST BASED VEHICLE TO VEHICLE COMMUNICATION USING APPLICATION-LEVEL PHASE ADJUSTMENTS

• US 20130094493A1
• Filed: 10/05/2012
• Published: 04/18/2013
• Est. Priority Date: 10/12/2011
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NX BV
• Inventors: Bril, Reinder Jaap, Batsuuri, Tseesuren, Lukkien, Johannes Jan
• Granted Patent: US 9,210,722 B2
• Time in Patent Office: Days
• US Class Current: 370/347
• 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 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 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.

2. A method as in claim 1 wherein the station collaborates with the multiple other stations manage channel access by employing the Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) mechanism at a message activation time.

3. A method as in claim 1 wherein at a message activation time the station first checks if the channel is busy or becomes busy for a duration of an Arbitration Inter Frame Space (AIFS), and if the channel is busy or becomes busy the station waits for the channel to become idle.

4. A method as in claim 3, wherein waiting for the channel to become idle is followed by waiting a random Back-off (Bf) period selected from an increasing Contention Window (CW).

5. A method as in claim 1 wherein two successive message activation times differ on average the broadcasting period.

6. A method as in claim 1, wherein the a phase of the periodically broadcast messages with respect to a periodic broadcast period is changed.

7. A method as in claim 1, wherein two successive message activation times differ the broadcasting period or a random time interval.

8. A method as in claim 1, wherein the station is configured with an elastic rate, and wherein, periodically after the elastic rate of message activation times have passed, two successive message activation times differ a random time interval.

9. A method as in claim 6, wherein the random time interval is random between zero and twice the broadcasting period.

10. A method as in claim 1, wherein the station is configured with an activation jitter, and wherein successive message activation times differ the broadcasting period plus a random value, the random value is the activation jitter minus a random value between 0 and twice the activation jitter.

11. A method as in claim 10 wherein a message has a message transmission time, and wherein the activation jitter is at least 2 times the transmission time of a message, more preferably at least 20 times the message transmission time.

12. A method as in claim 1, wherein the station is configured with an elastic rate and an activation jitter, and wherein successive message activation times differ the broadcasting period plus a random value, but periodically after the elastic rate of message activation times have passed, two successive message activation times differ a random time interval.

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

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

14. A station to periodically broadcast messages over a wireless channel to communicate to multiple other stations which transmit on the same channel, the station is configured to become ready to broadcast at successive message activation times, the station is configured to at a message activation time the station performing a Multiple Access mechanism to resolve channel access competition and to subsequently start transmission of a message, wherein at least two successive message activation times differ a random time interval.