Patent Application
20090153364
The present invention relates generally to vehicle transportation. The invention relates, more particularly, to the calculation of travel times for vehicles traversing through urban areas.
Congestion is a major problem in the traffic industry. Traffic congestion is a concern with regard to safety on the roads as well as conservation of energy. County Road Commissions and Departments of Transportation (hereinafter “DOTs”) need to be able to identify and relieve traffic congestion. DOTs use programmable traffic signals as a method to relieve traffic congestion. The ability of DOTs to make good use of the programmable traffic signals is limited by the difficulty in obtaining valid traffic flow and congestion information.
Currently, traffic engineers use derivative information to infer the real measure of performance, e.g., vehicle travel times. Vehicle travel time is the time it takes a vehicle to travel between two or more specified points; such as two intersections or a segment of roadway. Derivative information is information; such as traffic densities and flow speeds at points within the roadway network. Derivative information is obtained through the use of physical induction loops imbedded in the roadway, cameras mounted above the roadway, and temporary air-lines run across the roadway. However, presently there is no way to accurately measure the travel time of a vehicle without intruding into or specifically tracking a vehicle.
Alternate approaches of obtaining travel time information include harvesting information about cell phone mobility from the associations between cell phones and cellular towers, as well as from GPS probes to active phones. For example, as a mobile phone talks on a controlled telecom channel, the mobile phone registers with a basestation or cellular tower. A server in the operation center of the wireless service provider tracks the Electric Serial Number (“ESN”) of the cell phone within a vehicle. The server then calculates the travel time of the vehicle as it moves between towers. Since the ESN is tied to the account of a subscriber, this method creates a history of where the individual subscriber has been. Therefore, this method requires both the co-operation of the cellular carriers and the trust of the subscribers that privacy will not be violated. Additionally, since the cellular towers are not necessarily located near roadways, and cell sizes may be physically quite large, there is some inherent inaccuracy in this method of calculating the time a vehicle is traveling along a section of roadway or between two points.
What is needed is a method and system deployed without compromising any cellular subscriber trust and that can obtain actual accurate measurements of vehicle travel times between two discrete geographic street locations.
The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate various embodiments and to explain various principles and advantages all in accordance with the present invention.
a is an exemplary Flow Chart diagram of a WLAN Sniffer Uplink Operation in accordance with some embodiments of the invention.
b is an exemplary Flow Chart diagram of a WLAN Sniffer Message Selection Operation in accordance with some embodiments of the invention.
a and 4b are exemplary system diagrams in accordance with some embodiments of the present invention.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
Before describing in detail embodiments that are in accordance with the present invention, it should be observed that the embodiments reside primarily in combinations of method steps and apparatus components related to vehicle travel time calculation. Accordingly, the apparatus components and method steps have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.
In this document, relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” “includes,” “including” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by “comprises . . . a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.
It will be appreciated that embodiments of the invention described herein may be comprised of one or more conventional processors and unique stored program instructions that control the one or more processors to implement, in conjunction with certain non-processor circuits, some, most, or all of the functions of vehicle travel time calculation described herein. The non-processor circuits may include, but are not limited to, a radio receiver, a radio transmitter, signal drivers, clock circuits, power source circuits, and user input devices. As such, these functions may be interpreted as steps of a method to perform vehicle travel time calculation. Alternatively, some or all functions could be implemented by a state machine that has no stored program instructions, or in one or more application specific integrated circuits (ASICs), in which each function or some combinations of certain of the functions are implemented as custom logic. Of course, a combination of the two approaches could be used. Thus, methods and means for these functions have been described herein. Further, it is expected that one of ordinary skill, notwithstanding possibly significant effort and many design choices motivated by, for example, available time, current technology, and economic considerations, when guided by the concepts and principles disclosed herein will be readily capable of generating such software instructions and programs and ICs with minimal experimentation.
A method for detecting a radio signal from a vehicle and calculating a time the vehicle travels between two or more locations is disclosed. Various methods include receiving a radio signal from a vehicle, extracting information from the radio signal, transmitting the extracted information to a central server, storing the extracted information at the central server, comparing the extracted information against other extracted information, and calculating a travel time of the vehicle.
A system for detecting a radio signal from a vehicle and calculating a time the vehicle travels between two or more locations is disclosed. The system includes a device for detecting radio signals; a device for storing information associated to the detected signals; a device for comparing the information associated the detected signals to information associated to other detected signals and calculating a travel time of the vehicle.
Referring now to
A vehicle 106 contains a Wireless LAN device (hereinafter “WLAN”) 107. The WLAN 107 can be a device carried in by a driver or a passenger of the vehicle 106 such as a laptop computer, a personal data assistant, a cell phone with a wireless LAN-card, MP3 player, or any other device with a WLAN chipset contained therein. The WLAN 107 may also be an integrated part of the vehicle 106. The WLAN 107 can be an 802.11b device. However, artisans of ordinary skill in the art will appreciate that the WLAN 107 can be an 802.11a, 802.11g, or 802.11n device or it can be another type of device capable of transmitting a wireless or radio signal.
When in the “ON” state, the WLAN 107 in the vehicle 106 is engaged in WLAN radio traffic 108. The WLAN radio traffic 108 comprises probes, beacons, and messages packets, transmitted by the WLAN 107 on a periodic basis. Probes are signals to perform radio checks to see if there are any other active WLAN devices in the area. A WLAN sends a probe by transmitting signals requesting any receiving (or listening) device to reply with a reply signal. The WLAN 107 is also listening, e.g., ready to receive, for beacons coming from access points (not shown). If the WLAN 107 has a list of previously seen access points in its database, the WLAN 107 will probe (i.e., “active scanning”) to see if any of these previously seen access points are accessible. The probes may be transmitted multiple times per second, once per second, once every several seconds, once per minute, or at other predetermined intervals depending upon the WLAN chipset and its programming. Additionally, the listening for beacons (i.e., “passive scanning”) may also occur on a periodic basis of multiple times per second, once per second, or at other predetermined intervals depending upon the WLAN chipset. The messages packet comprises a unique identifier (e.g. a MAC or Media Access Control address), a received signal strength, and other information depending upon the WLAN chipset. The MAC address is an identification that is unique to the WLAN 107 device. Each WLAN device contains a MAC address provided as part of the manufacturing and initial configuration process. The received signal strength is the strength of the signal, as measured in decibels (dB), at the time the message is received by the sniffer 102.
As stated hereinabove, the VTTC 100 includes a number of sniffers 102. The sniffers 102 are mounted at intersection #1110 and intersection #2112. Artisans of ordinary skill in the art will appreciate that two intersections are shown for exemplary purposes only and that the VTTC 100 may include many more sniffers 102 mounted at many more intersections. The sniffers 102 may be mounted on traffic signals, street lights, utility poles, billboards, cellular towers, or any other structure adjacent to a roadway portion of interest. One sniffer 102 may be mounted at a location or multiple sniffers 102 may be mounted at the location.
Referring now to
The sniffer 102 can have an exterior box or case 202. The box 202 can be a weather resistant box or a housing structure that may provide a level of climate control. The box 202 may also have a removable panel or access door 204. The sniffer 102 has a Network Protocol Analyzer (WLAN Detection Device) 206. The network protocol analyzer 206 is connected to a power source 208. The power source 208 may utilize either AC or DC (battery or solar) power. The network protocol analyzer 206 may be connected directly to the power source 208 or through a switch 210. The network protocol analyzer 206 is also connected to an antenna 212. A single antenna 212 may be used or multiple antennas 212 may be used in a diversity mode. The network protocol analyzer 206 has a backhaul connection 214. The backhaul connection 214 is the data connection for providing data to the central server 104 (shown in
Referring now to
Referring now to
Referring to
Therefore, as the vehicle 106 approaches and passes intersection #1110, the sniffer 102 at intersection #1110 receives multiple message packets from the WLAN 107 in the vehicle 106. Each of these multiple message packets contains the MAC address of the WLAN 107 and has a received signal strength. The received signal strength for each of the multiple message packets will be different depending upon the proximity of the vehicle 106 to the sniffer 102 at intersection #1110. The strength of the received signal 108 increases as the vehicle 106 gets closer to the intersection #1110, e.g., the decibels (dB) of the received signal 108 decrease. The sniffer 102 attaches a time stamp and sniffer unique location identifier on each message packet transmitted by the WLAN 107 in the vehicle 106. The sniffer 102 reads the packets received from the WLAN 107. The sniffer 102 determines which received signal has the lowest decibels (e.g., the highest received signal strength). The signal with the lowest decibels corresponds to the packet sent by the WLAN 107 when the vehicle 106 was closest in proximity to the sniffer 102; such as when the vehicle 106 is directly under, proximate or nearest to, the sniffer 102 at the intersection #1110. The sniffer 102 selects the packet with the highest received signal (e.g., lowest decibels), provides at least the timestamp, the MAC address, and the sniffer 102 location information identifier for transmission to the central server 104 (see
Referring now to
Therefore, as the vehicle 106 approaches and passes intersection #2112, the sniffer 103 at intersection #2112 receives multiple message packets from the WLAN 107 in the vehicle 106. Each of these multiple message packets contains the MAC address of the WLAN 107 in the vehicle 106 and has a received signal strength. The received signal strength for each of the multiple message packets will be different depending upon the proximity of the vehicle 106 to the sniffer 103 at intersection #2112. The strength of the received signal 108 increases as the vehicle 106 gets closer to the intersection #2112, e.g., the decibels (dB) of the received signal 108 decreases. The sniffer 103 attaches a time stamp and sniffer unique location identifier on each message packet transmitted from the WLAN 107 in the vehicle 106. The sniffer 103 reads the packets received from the WLAN 107. The sniffer 103 determines which received signal has the lowest decibels (e.g., the highest received signal strength). The signal with the lowest decibels corresponds to the packet sent by the WLAN 107 when the vehicle 106 was closest in proximity to the sniffer 103; such as when the vehicle 106 is directly under, proximate or nearest to, the sniffer 103 at the intersection #2112. The sniffer 103 selects the packet with the highest received signal (e.g., lowest decibels) for transmission to the central server 104 (see
As stated hereinabove with reference to
In an additional embodiment, the sniffers 102, 103 can store the message packets, with attached timestamps, in the sniffer 102, 103 memory. The sniffer 102, 103 can then transmit the message packets, with attached timestamp, MAC address, and sniffer 102, 103 unique location identifier, periodically at predetermined intervals.
The central server 104 includes a database (not shown). The database can be setup in many ways known in the art. The central server 104 stores the filtered message packets in the database. Each filtered message packet is stored as a record in the database. The records are stored in the database for a 24 hour period of time. Artisans of ordinary skill in the art will appreciate that the 24 hour period of time is for exemplary purposes and that any designated time period from about 1 minute to one year may be used depending upon the type of time interval statistics and data points necessary for final calculations or traffic trend analysis. The oldest records are normally deleted prior to newer records, but blocks of records may be deleted from time to time depending upon database memory constraints and database management practices. Thus the first record recorded is the first record deleted. The second record recorded is the second record deleted, and so on.
Referring now to
The central server 104 then performs a matching operation 510 to determine if a same MAC address appears in more than one recorded message packet in the database. If no matching MAC addresses are found, the central server 104 returns to the “wait and see” loop 506. If the same MAC address is found in at least two message packets, the central server 104 runs an algorithm 512 to calculate the travel time. The algorithm 512 first confirms that the MAC address was received from two separate sniffer locations, e.g., received at intersection #1110 and intersection #2112 in
As illustrated in the flow chart in
The algorithm then collects segment travel times 606. The timestamps and sniffer locations from the selected messages are also recorded with the travel time records. The algorithm then averages the recorded travel times occurring during pre-selected time periods throughout the day. As an example, the algorithm can average the travel times occurring between the hours of 7 a.m. and 9 a.m. to obtain an average travel time for the “rush hour” time period. The algorithm 512 then uses this data to update a statistical model 608.
The algorithm can be programmed to anticipate prior entries and driving patterns. If the same MAC addresses is routinely received by the sniffer 102 at the same locations during the same time periods, e.g., at intersection #1110 and intersection #2112 during rush hour, the algorithm can look for those same repeated or familiar MAC addresses first.
The central server 104 can then post and display the results of the algorithm 514 in any number of manners as is known in the art. An operator can also perform a query on the results (not illustrated).
In an additional embodiment, the selection of the message packet with the strongest received signal is performed at the central server 104. The sniffer 102 would filter the message packets to discard data not necessary to the calculation of vehicle travel times, as described with reference to
In the foregoing specification, specific embodiments of the present invention have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present invention. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.
