Abstract:
A method for identifying traffic information for at least one sub-link includes receiving traffic information including a sub-link identifier enabling a determination of whether the received traffic information includes sub-link information, traffic status information enabling a determination of traffic information for a sub-link, information identifying a link within which the sub-link is located, and sub-link location information enabling a determination of a portion of the link that corresponds to the sub-link. The method also includes determining, based on the sub-link identifier whether the received traffic information includes sub-link information and dependent on whether the sub-link identifier enables a determination that the received traffic information includes sub-link information.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority from U.S. provisional application No. 60/681,971 filed May 18, 2005, which is titled “Traffic information signal and method and apparatus for providing the signal,” and Korean application No. 10-2005-0099532, filed Oct. 26, 2005, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Field 
     The present document relates to providing traffic information including sub-links of link and using the provided traffic information. 
     2. Description of the Related Art 
     With the advancement in digital signal processing and communication technologies, radio and TV broadcasts are being digitalized. Digital broadcasting enables provision of various information (e.g., news, stock prices, weather, traffic information, etc.) as well as audio and video content. 
     SUMMARY 
     In one general aspect, a method for identifying traffic information for at least one sub-link is provided. The method includes receiving traffic information including a sub-link identifier enabling a determination of whether the received traffic information includes sub-link information, traffic status information enabling a determination of traffic information for a sub-link, information identifying a link within which the sub-link is located, and sub-link location information enabling a determination of a portion of the link that corresponds to the sub-link. The method also includes determining, based on the sub-link identifier whether the received traffic information includes sub-link information and dependent on whether the sub-link identifier enables a determination that the received traffic information includes sub-link information. 
     Implementations may include one or more additional features. For instance, the method may include receiving a data length associated with the traffic information, a text name or description of the sub-link, and a start and end location of the sub-link. Receiving sub-link location information may include receiving vertex, coordinate, or longitude and latitude information that corresponds to a location associated with the sub-link. Receiving sub-link location information may include receiving vertex, coordinate, or longitude and latitude information that corresponds to the link. 
     Also, in the method, after the sub-link is determined to be within the link, additional sub-link information to enable deletion of the sub-link may be received. The sub-link may, only if the received additional sub-link information includes an identifier that enables a determination that the sub-link is to be deleted, be deleted. The received additional sub-link information may specify the sub-link identifier and the identifier of the link. 
     The method may further include receiving additional sub-link information after the sub-link is determined to be within the link, and using the received additional sub-link information to alter the position of the determined sub-link within the link. The received additional sub-link information may include at least one of a start location and an end location of the determined sub-link. The received additional sub-link information may be used to extend or shorten a length of the sub-link. Additional sub-link information may be received after the sub-link is determined to be within the link, and the received additional sub-link information may be used to alter the position of the determined sub-link beyond location constraints associated with the link. 
     Also, the method may further include receiving information corresponding to a message management structure including information corresponding to a generation time of the information included in the message management structure. The generation time included within the received message management structure may relate to the status information for the sub-link. The generation time included within the received message management structure may relate to a plurality of message component structures that correspond to more than one of a predicted or current traffic tendency, a predicted or current amount of traffic, a predicted or current speed, and a predicted or current time to traverse a particular link. Receiving information reflecting a message component structure may include receiving information associated with identification and configuration of the sub-link. 
     Further, in the method, the traffic status information for the sub-link may include information associated with at least one of a predicted or current travel speed on the sub-link, a predicted or current congestion level or amount on the sub-link, a predicted or current travel time to traverse the sub-link, or a predicted or current speed of travel on the sub-link, may be received. The traffic status information for the sub-link may differ from traffic status information for the link. The traffic status information for the sub-link may be received after receiving traffic status information that is configured to reveal status for the link, the sub-link status information being configured to enable updated status information for a portion of the link corresponding to the sub-link. Receiving sub-link information may include receiving a text descriptor associated with the sub-link. 
     In another general aspect, a traffic information communication device is provided. The device includes a data receiving interface configured to receive traffic information including a sub-link identifier enabling a determination of whether the received traffic information includes sub-link information and traffic status information enabling a determination of traffic information for a sub-link. The device is also configured to receive information identifying a link within which the sub-link is located, and sub-link location information enabling a determination of a portion of the link that corresponds to the sub-link. The device also includes a processing device configured to process the traffic information received from the data receiving interface and to determine sub-link status information based at least in part on the traffic information received. 
     Implementations may include one or more additional features. For instance, the data receiving interface may receive additional sub-link information after the sub-link is determined to be within the link, and the processing device may be configured to use the received additional sub-link information to alter the position of the determined sub-link within the link. The received additional sub-link information may include at least one of a start location and an end location of the determined sub-link. The processing device may be configured to use the received additional sub-link information to extend or shorten a length of the sub-link. The data receiving interface may receive additional sub-link information after the sub-link is determined to be within the link, and the processing device may be configured to use the received additional sub-link information to alter the position of the determined sub-link beyond location constraints associated with the link. 
     In a further general aspect, an apparatus for identifying traffic information for at least one sub-link is provided. The apparatus includes means for receiving traffic information including a sub-link identifier enabling a determination of whether the received traffic information includes sub-link information, traffic status information enabling a determination of traffic information for a sub-link, information identifying a link within which the sub-link is located, and sub-link location information enabling a determination of a portion of the link that corresponds to the sub-link. The method also includes means for determining, based on the sub-link identifier whether the received traffic information includes sub-link information and means for, dependent on whether the sub-link identifier enables a determination that the received traffic information includes sub-link information. 
     Implementations may include one or more additional features. For instance, the means for receiving may include means for receiving additional sub-link information after the sub-link is determined to be within the link, the apparatus further comprising means for using the received additional sub-link information to alter the position of the determined sub-link within the link. 
     The method may also include means for using the received additional sub-link information to extend or shorten a length of the sub-link. The means for receiving may include means for receiving additional sub-link information after the sub-link is determined to be within the link, the apparatus may further include means for using the received additional sub-link information to alter the position of the determined sub-link beyond location constraints associated with the link. 
     The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings illustrate various implementations. In the drawings: 
         FIG. 1  illustrates a schematic diagram of a network through which traffic information is provided; 
         FIG. 2   a  illustrates a partial syntax of a component frame including traffic information; 
         FIG. 2   b  illustrates a format of a TPEG-CTT message with an emphasis on status components delivering traffic information; 
         FIG. 2   c  illustrates a format of a TPEG-CTT message with an emphasis on coordinate components delivering link information; 
         FIG. 3   a  illustrates a syntax of a link information component 
         FIG. 3   b  illustrates a format of the TPEG-CTT message with an emphasis on link information components; 
         FIG. 3   c  illustrates a format to transmit information on a sub-link through coordinate components; 
         FIG. 4  illustrates a block diagram of a navigation terminal that receives traffic information transmitted from a server; and 
         FIGS. 5   a  through  5   c  illustrate examples of displaying traffic information such as average speed in a link, and a sub-link. 
     
    
    
     DETAILED DESCRIPTION 
     One such use for digital broadcasts is to satisfy an existing demand for traffic information. Proposals that involve the use of digital broadcasts for this purpose contemplate the use of standardized formatting of traffic information to be broadcast. This approach may be used to enable the use of traffic information receiving terminals made by different manufacturers, which each could be configured to detect and interpret traffic information broadcast in the same way. 
       FIG. 1  is a schematic diagram of a network through which traffic information is provided. A traffic information providing server  100  in a broadcast station may transmit traffic information, e.g., traffic congestion information collected from various sources (e.g., operator input, or information received from another server or probe cars through a network  101 ) wirelessly so that a traffic information receiving terminal (e.g., navigation system installed in a car  200 ) may receive the traffic information. In the below explanation about implementations, the traffic information means traffic congestion information. 
     The traffic information wirelessly transmitted from the traffic information providing server  100  may be of the form of a component frame. As shown in  FIG. 2   a , a component frame may include a field  201  indicative of the number of messages included therein and a sequence of transport protocol expert group messages  202 , where the number of the messages being equal to the value stored in the field  201 . The transport protocol expert group message will be referred to as the TPEG-CTT message hereinafter. 
     As shown in  FIGS. 2   b  and  2   c , one message segment of the sequence  202 , i.e., one TPEG-CTT message, may include a message management container including information on date and time, the message occurrence time, etc., a congestion and travel-time information (CTT) container, and a TPEG-CTT location container. The CTT container may include a field  211  indicative of the number of CTT components included in the CTT container and the TPEG-CTT location container. The field  211  may be followed by CTT components, the number of which is equal to the value stored in the field  211 . 
     In various implementations, if a CTT component includes traffic congestion information, the CTT component is given an ID of 0x80, as shown in  FIG. 2   b , and includes one or more status components therein. Each status component may include an ID indicative of the information included therein. For example, a status component including an ID of 0x00 delivers the average speed in a link. A status component including an ID of 0x01 delivers link travel time. A status component including and ID of 0x03 delivers information on the degree or type of congestion. In the description, specific IDs are described as assignments to structures associated with specific information. The actual value of an assigned ID (e.g., 0x80) is exemplary, and different implementations may assign different values for specific associations or circumstances. Thus, the CTT component may be used to provide various different types of data that may be signaled based on an identifier. For example,  FIG. 2B  illustrates components with identifiers of 0x00 and 0x01 signaling, respectfully, speed and travel-time information. 
     Further, according to the various implementations if a CTT component includes link location information, the CTT component is given an ID of 0x90, as shown in  FIG. 2   c , and includes one or more TPEG-CTT location sub-containers. Each TPEG-CTT location sub-container ‘Tpeg_loc 13  container’ includes one or more TPEG-CTT location components, each of which includes one or more coordinate components having an ID of 0x00. Each coordinate component delivers information on a link or links for which the status component includes traffic information. A link may refer to a road segment which starts and ends at junctions and has no junction in between. A coordinate component including an ID of 0x00 includes information on the link type (e.g., express way, national road, etc). A coordinate component including an ID of 0x01 includes coordinate information which may be expressed in the WGS84 format. A coordinate component including an ID of 0x03 includes link description information and a coordinate component including an ID of 0x10 includes link identification information. 
     The server  100  may construct the TPEG-CTT information as shown in  FIGS. 2   a  through  2   c  from traffic information collected from various sources and may transmit the constructed TPEG-CTT information to traffic information receiving terminals wirelessly. 
     Information may be provided on a specific link in more detail. For example, if a driver wants to go to a location within a link which ends at an intersection and there is traffic congestion around the intersection, the average speed in the road segment is very low. If the driver estimates the approximate arrival time based on the average speed in the road, the actual arrival time may significantly deviate from the estimated arrival time, such as, for example, when the destination is near the congested intersection. As a result, the driver may benefit from detailed traffic information around the specific location. 
     In various implementation, the server  100  collects traffic information in a centralized manner, and creates and provides traffic information for a sub-link within a link. In one implementation, a sub-link is created if the difference between the average speed in the sub-link and the average speed in the other segment within the link exceeds a predetermined threshold level (e.g., 5 m/s or 10 m/s). 
     A process, according to various implementations, for providing traffic information on a virtual sub-link that does not correspond to a full actual link will now be described in detail. 
     To provide traffic information on a sub-link  10  within a link, the server  100  may construct a link information component, as shown in  FIG. 3   a , and may deliver the link information component via a TPEG-CTT location sub-container. The link information component is allocated an ID of 0x01 distinct from the ID of a coordinate component. 
     As shown in  FIG. 3   b , each link information component may include a link allocating sub-component  301  for allocating a sub-link as a virtual link within a link and a link canceling sub-component  302  for canceling an existing sub-link. A sub-link need not be an actual link but may be treated as a link in that congestion and traveling time information may be provided for each sub-link. 
     The link allocating sub-component  301  has an ID of 0x00 and may include a sub-link ID to allocate to a sub-link to be established, the ID of a parent link within which the sub-link is established, coordinate information indicative of the start and end positions of the sub-link, and/or a descriptor. In various implementations, the coordinate information may be a pair of 4-byte longitude and 4-byte latitude or indices of the vertices corresponding to the start and end positions of the sub-link formed within the parent link. The link canceling sub-component  302  has an ID of 0x01 and may include a sub-link ID, which is the ID of the sub-link to be canceled, and a parent link ID. 
     The server  100  may construct the TPEG-CTT information as shown in  FIGS. 2   a  through  2   c  from traffic information collected from various sources and may transmit the constructed TPEG-CTT information to traffic information receiving terminals wirelessly. Under various circumstances, such as, for example, during the transmission, if the difference between the average speed in a local segment within a link and the average speed in the other segment of the link exceeds a threshold value, the server  100  may create a link allocating sub-component  301  for establishing the local segment as a sub-link and may deliver the link allocating sub-component  301  via the link information component  300 . 
     In another implementation, information on sub-link allocation and cancellation may be carried by a coordinate component including an ID of 0x00, as shown in  FIG. 3   c . In this case, IDs of, for example, 0x11 and 0x12 are allocated to a coordinate component carrying sub-link information to distinguish from other coordinate components carrying road-type list, WGS84, link description, and link identification. 
     In this implementation, location information that may be needed for allocating a sub-link, for example, WGS84 information on start and end points and sub-link description information, may be included dispersedly in both a WGS84 component and a description component shown in  FIG. 2   c.    
     The server  100  may transmit traffic information (e.g., average speed, link travel time, the degree of congestion, etc) for the sub-link in a similar manner to links. 
     According to various implementations, if the length of the sub-link which shows an average speed deviation larger than a threshold level changes, i.e., the change in the length of the sub-link exceeds a predetermined length (e.g., 20 m in the case of downtown roads), the server  100  may create and may transmit a link allocating sub-component (or sub-link allocating coordinate component) for reallocating a sub-link including the changed start and end positions. In this case, the server  100  may allocate the sub-component an ID, e.g., 0x02 (or 0x13) instead of 0x00 (or 0x11 indicative of a sub-link allocating coordinate component) to inform traffic information receiving terminals that a sub-link is established again within a parent link which already has a sub-link therein. A similar process may be used to shorten or move a sub-link, with the creating of a link shortening sub-component or a link moving sub-component. 
     After a sub-link is allocated in a link, the average speed in the link and the average speed in the sub-link may be provided separately. 
     In one implementation, if the difference between the average speed in a sub-link within a link and the average speed in the other segment of the link goes below the same or a different threshold value while the server  100  transmits traffic information for the sub-link, the server  100  may create a link canceling sub-component  302  for canceling the allocated sub-link as shown in  FIG. 3   b  and may deliver the link canceling sub-component  302  via the link information component  300 . 
       FIGS. 4-6  are example implementations of systems for receiving and utilizing traffic information. Other systems may be organized differently or include different components. Specifically,  FIG. 4  is an example of a block diagram of a navigation terminal that receives traffic information transmitted from the server  100 . 
     The navigation terminal includes a tuner  1  for receiving modulated traffic information signals by resonating at the required frequency band, a demodulator  2  for outputting traffic information signals by demodulating the modulated signals from the tuner  1 , a TPEG-CTT decoder  3  for extracting traffic information by decoding the demodulated traffic information signals, a GPS module  8  for calculating the current position (i.e., latitude, longitude, and altitude) by receiving signals from a plurality of satellites, storage structure  4  for storing various graphic data and an electronic map including information on links and nodes, an input unit  9  for receiving user input, a navigation engine  5  for controlling screen display based on the user input, the current position, and extracted traffic information, a memory  5   a  for storing data temporarily, an LCD panel  7  for displaying data, and an LCD drive  6  for driving the LCD panel  7  according to data to be presented. The input unit  9  may be a touch screen incorporated into the LCD panel  7 . 
     The tuner  1  tunes to the frequency of the signals transmitted by the server  100  and the demodulator  2  demodulates the tuned signals in a predetermined manner. The TPEG-CTT decoder  3  extracts TPEG-CTT messages, as shown in  FIGS. 2   a  through  2   c  and  FIG. 3   a  and  3   b  (or  3   c ), and stores the TPEG-CTT messages temporarily. Interpreting the temporarily stored TPEG-CTT messages, the TPEG-CTT decoder  3  sends the extracted information and/or control data to the navigation engine  5 . Though various kinds of information is provided for the navigation engine  5  by the TPEG-CTT decoder  3 , for purposes of brevity, the following description will focuses on the method for allocating sub-links and the method for processing traffic information for sub-links. 
     The TPEG-CTT decoder  3  extracts data/time and message occurrence time included in the message management container of each TPEG-CTT message and determines if the following container is a CTT event container based on ‘message element’ information (i.e. an identifier). If it is determined that the following container is a CTT event container, the TPEG-CTT decoder  3  provides the navigation engine  5  with the information obtained from the CTT component included in the CTT event container so that the navigation engine  5  can display congestion and travel-time information and link information, which will be described below. Providing the navigation engine  5  with the information may include determining, based on identifiers, that the traffic information includes a message management container including status or sub-link information within various message components within the message management container. The components may each include different status or sub-link information associated with different links, composite links, or locations and identifiers associated with the different status or sub-link information. The containers and components may each include information associated with a generation time, version number, data length, and identifiers of included information. 
     The TPEG-CTT decoder  3  then extracts information on the link location about which the previously extracted information may be created from the following TPEG-CTT location container. The position information may be, for example, the coordinates (i.e., latitudes and longitudes) of the start and end positions or a link ID, depending on the type of the TPEG-CTT location container. If the navigation terminal is equipped with the storage structure  4 , the navigation engine  5  finds the link location about which the received information is created with reference to information on each link and node stored in the storage structure  4 . The navigation engine  5  may convert the coordinates of the link into the link ID or vice versa. 
     In the implementation of  FIG. 3   b , the TPEG-CTT decoder  3  may determine if a link information component including an ID of 0x01 is delivered via a TPEG-CTT location sub-container and if so, may extract each sub-component from the link information component. If the extracted sub-component is a link allocating sub-component (e.g., includes an appropriate identifier), such as including an ID of 0x00 for allocating a sub-link, the TPEG-CTT decoder  3  may extract the ID of the sub-link to allocate, the ID of the parent link, information on the start and end positions, and descriptor and provides the extracted information for the navigation engine  5  so that the extracted information may be stored as a temporary link entry in the memory  5   a . If the extracted sub-component is a link canceling sub-component (e.g., includes an appropriate identifier), such as including an ID of 0x01 for canceling an existing sub-link, the TPEG-CTT decoder  3  may make a request for removing a temporary link entry including an ID that is the same as the sub-link ID of the sub-component so that the navigation engine  5  can remove the sub-link entry from the memory  5   a.    
     In the implementation of  FIG. 3   c , a sub-link allocating coordinate component or a sub-link cancellation coordinate component may be extracted from a TPEG-CTT location component including ID of 0x00 included in a TPEG-CTT location sub container, and the above-explained operations may be conducted according to information included in the extracted component. 
     The navigation engine  5  reads a part of the electronic map centered around the position coordinates received from the GPS module  8  from the storage structure  4  and displays the map on the LCD panel  7  via the LCD drive  6 . A particular graphic symbol is displayed at the location corresponding to the current position on the LCD panel  7 . 
     The navigation engine  5  may display the average speed or average travel time in a link received from the TPEG-CTT decoder  3  at a location corresponding to the coordinates or link ID delivered via the TPEG-CTT location container following the container delivering the average speed or average travel time information. In this case, the navigation engine  5  may search the storage structure  4  for the link corresponding to the coordinates or link ID received from the TPEG-CTT location container. If the link is not found, then the navigation engine  5  may determine if there is a matched temporary link entry in the memory  5   a . In this search operation, temporarily allocated sub-links as well as actual links may be searched. The traffic information for the link and/or sub-link specified by the search operation may be extracted from the corresponding status component included in a CTT component including an ID of 0x80. 
     There are various alternative methods for the navigation engine  5  to display traffic information. For example, the navigation engine  5  may show links in different colors according to the average speed in the links, as shown in  FIGS. 5   a  and  5   b , or may show the average speed with number in each link as shown in  FIG. 5   c . In  FIGS. 5   a  and  5   b , the red, orange, green, blue colors indicate average speeds of 0-10 km, 1020 km, 2040 km, over 40 km, respectively. 
     If the navigation terminal is not equipped with the storage structure  4  for storing an electronic map, the terminal may show the average speed or the travel time in links located in front of the current position with different colors as shown in  FIG. 5   b , or with figures as shown in  FIG. 5   c . If the route of the car with the navigation terminal installed is determined, the navigation terminal may show the average speed in the links included in the determined route instead of the links located in front of the current position. 
     If the traffic information for a temporary link entry stored in the memory  5   a , i.e., a sub-link, is received, the navigation engine  5  may display the traffic information for the sub-link with colors or figures, as marked ‘A’ in  FIGS. 5   a  through  5   c  to be distinguished from the traffic information for the parent link. 
     If the terminal in  FIG. 4  is equipped with a voice output device, the terminal may output received traffic information for a specified link or sub-links included in a specified route in voice. If the specified link or one of the links included in the specified route is a sub-link, a voice message describing the average speed in the sub-link is generated. If the descriptor in the link allocating sub-component (or link description component) shown in  FIG. 3   b  is “xxx”, the voice message may be “the average speed in xxx segment is nn”. 
     The present disclosure enables estimation of an approximate arrival time even when the roads around the destination are congested locally by providing additional traffic information for a road segment showing a big deviation in the average speed from the other segment of the road. 
     In the previous discussion, wherever average speed has been referenced, it may be interpreted as either of actual or predicted average speed, or it may be replaced or supplemented with other status or component based information, such as, for example, actual or predicted travel time (e.g., to traverse the link), congestion tendency, and/or congestion amount. 
     The foregoing description has been presented for purposes of illustration. Thus, various implementations with improvements, modifications, substitutions, or additions within the spirit and scope as defined by the following appended claims.