Vehicle traffic monitoring using cellular telephone location and velocity data
First Claim
1. A vehicular traffic monitoring system for communicating with a plurality of mobile telephones carried in moving vehicles and capable of determining their respective geographic positions and velocities, comprising:
- a data collector for receiving data samples from said plurality of mobile telephones, each data sample comprising instantaneous location and velocity information of a respective mobile telephone at a respective time;
a road segment identifier coupled to said data collector for finding matching data samples wherein a respective instantaneous location corresponds to one of a plurality of road segments monitored by said traffic monitoring system;
a recursive sliding average calculator coupled to said road segment identifier for determining an average speed corresponding to matched data samples for a particular one of said road segments in response to a predetermined sliding window having a predetermined number of said matched data samples wherein said average speed is determined as a recursive sliding average An in response to an nth one of said matched data samples Sn, a previous average speed An−
1, and a predetermined number W of matched data samples in said predetermined sliding window;
a state change detector coupled to said recursive sliding average calculator for detecting a traffic state change at said road segment in response to said average speed in said predetermined sliding window determined at first and second times; and
a congestion indicator coupled to said state change detector, said congestion indicator indicating either a congested state or a clear state of said respective road segment in response to said detected traffic state change.
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Abstract
A vehicular traffic monitoring system communicates with a plurality of mobile communication devices carried in moving vehicles and capable of determining their respective geographic positions and velocities. A data collector receives data samples from the plurality of mobile communication devices, each data sample comprising instantaneous location and velocity information of a respective mobile telephone at a respective time. A road segment identifier is coupled to the data at the collector for matching data samples wherein a respective instantaneous location corresponds to one of a plurality of road segments monitored by the traffic monitoring system. A sliding average calculator coupled to the road segment identifier determines an average speed corresponding to matched data samples for a particular one of the road segments in response to a predetermined sliding window. A state change detector coupled to the sliding average calculator detects a traffic state change at the road segment in response to the average speed in the predetermined sliding window determined at first and second times. A congestion alerting mechanism coupled to the state change detector routes notifications when the respective road segment state changes (either to a congested state or a clear state).
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Citations
20 Claims
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1. A vehicular traffic monitoring system for communicating with a plurality of mobile telephones carried in moving vehicles and capable of determining their respective geographic positions and velocities, comprising:
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a data collector for receiving data samples from said plurality of mobile telephones, each data sample comprising instantaneous location and velocity information of a respective mobile telephone at a respective time;
a road segment identifier coupled to said data collector for finding matching data samples wherein a respective instantaneous location corresponds to one of a plurality of road segments monitored by said traffic monitoring system;
a recursive sliding average calculator coupled to said road segment identifier for determining an average speed corresponding to matched data samples for a particular one of said road segments in response to a predetermined sliding window having a predetermined number of said matched data samples wherein said average speed is determined as a recursive sliding average An in response to an nth one of said matched data samples Sn, a previous average speed An−
1, and a predetermined number W of matched data samples in said predetermined sliding window;
a state change detector coupled to said recursive sliding average calculator for detecting a traffic state change at said road segment in response to said average speed in said predetermined sliding window determined at first and second times; and
a congestion indicator coupled to said state change detector, said congestion indicator indicating either a congested state or a clear state of said respective road segment in response to said detected traffic state change. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
a notification system coupled to said congestion indicator for informing at least some of said moving vehicles to avoid a respective road segment when its respective congestion indicator indicates a congested state.
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3. The traffic monitoring system of claim 1 further comprising:
a route calculator coupled to said congestion indicator for determining a preferred route between a current position and a desired destination provided in a route request from a user, said preferred route avoiding any of said road segments for which a respective congestion indicator indicates a congested state.
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4. The traffic monitoring system of claim 1 further comprising:
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an interval identifier coupled to said road segment identifier for determining a respective recurring time-of-day interval of said data samples for a respective road segment;
an averager coupled to said interval identifier for determining an overall average speed corresponding to said data samples for said recurring time-of-day interval; and
a baseline database storing baseline averages corresponding to a plurality of said recurring time-of-day intervals for said plurality of road segments.
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5. The traffic monitoring system of claim 4 further comprising:
a route calculator coupled to said baseline database for determining a preferred route between a current position and a desired destination provided in a route request from a user, said preferred route being determined in response to said baseline averages of said road segments for a respective time-of-day interval corresponding to said route request.
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6. The traffic monitoring system of claim 4 further comprising:
a route calculator coupled to said baseline database and said congestion indicator for determining a preferred route between a current position and a desired destination provided in a route request from a user, said preferred route avoiding any of said road segments for which a respective congestion indicator indicates a congested state, and said preferred route being determined in response to said baseline averages of said road segments for a respective time-of-day interval corresponding to said route request.
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7. The traffic monitoring system of claim 1 wherein said mobile telephones operate within a wireless cellular network, wherein each one of said data samples is obtained from a respective mobile telephone during a registration operation to said wireless cellular network, and wherein said data collector is coupled to said wireless cellular network for initiating registration operations for selected mobile telephones.
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8. The traffic monitoring system of claim 1 wherein said state change detector calculates a difference between said average speeds determined at first and second times and compares said difference with a threshold to detect said traffic state change.
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9. The traffic monitoring system of claim 1 wherein said state change detector includes a cache for storing a plurality of said average speeds during a predetermined period including said first and second times, wherein said state change detector identifies a maximum average speed and a minimum average speed within said cache, and wherein said traffic state change is detected when a difference in relative magnitude of said maximum average speed and said minimum average speed is greater than a threshold.
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10. The traffic monitoring system of claim 1 wherein said average speed is determined by said recursive sliding average calculator according to a recursive formula comprising:
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11. A method of monitoring vehicular traffic on a plurality of road segments, said method comprising the steps of:
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receiving data samples from a plurality of mobile telephones carried in moving vehicles and capable of determining their respective geographic positions and velocities, each data sample comprising instantaneous location and velocity information of a respective mobile telephone at a respective time;
matching data samples with respective road segments whenever a respective instantaneous location corresponds to a stored location of a respective one of said road segments;
determining an average speed corresponding to a recursive average of said matched data samples for a particular one of said road segments in response to a predetermined sliding window having a predetermined number of said matched data samples wherein said average speed is determined as a recursive sliding average An in response to an nth one of said matched data samples Sn, a previous average speed An−
1, and a predetermined number W of matched data samples in said predetermined sliding window;
detecting a traffic state change at said road segment in response to a change in said average speed in said predetermined sliding window determined at first and second times; and
indicating either a congested state or a clear state of said respective road segment in response to said detected traffic state change. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
determining a respective recurring time-of-day interval of said data samples for a respective road segment;
determining an overall average speed corresponding to said data samples for said recurring time-of-day interval; and
storing baseline averages corresponding to a plurality of said recurring time-of-day intervals for said plurality of road segments.
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15. The method of claim 14 further comprising the step of determining a preferred route between a current position and a desired destination specified in a route request from a user, said preferred route being determined in response to said baseline averages of said road segments for a respective time-of-day interval corresponding to said route request.
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16. The method of claim 14 further comprising the step of determining a preferred route between a current position and a desired destination specified in a route request from a user, said preferred route avoiding any of said road segments for which a respective congestion indicator indicates a congested state, and said preferred route being determined in response to said baseline averages of said road segments for a respective time-of-day interval corresponding to said route request.
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17. The method of claim 11 wherein said mobile telephones operate within a wireless cellular network, wherein each one of said data samples is obtained from a respective mobile telephone during a registration operation to said wireless cellular network, and wherein said data collector is coupled to said wireless cellular network for initiating registration operations for selected mobile telephones.
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18. The method of claim 11 wherein said step of detecting a traffic state change is comprised of:
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calculating a difference between said average speeds determined at first and second times; and
comparing said difference with a threshold.
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19. The method of claim 11 wherein said step of detecting a traffic state change is comprised of:
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storing in a cache a plurality of said average speeds during a predetermined period including said first and second times;
identifying a maximum average speed and a minimum average speed within said cache; and
detecting whether a difference in relative magnitude of said maximum average speed and said minimum average speed is greater than a threshold.
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20. The method of claim 11 wherein said recursive average is determined according to a recursive formula comprising:
Specification