Abstract:
An access control system including a base station located near a stationary target site used to control access to the stationary target site and satellite access station coupled to the exterior of a satellite target site used to control access to the satellite target site. The base station includes an identification device, storage device, a control unit, a user interface and a transceiver. A master database containing a list of access information for all of the satellite access stations is stored in the storage device. Each satellite access station includes a second identification device, a second storage device, a control unit and a second transponder. A satellite database contains a list of access information for the satellite target site. Information contained in the master database for a particular satellite access station is provided to the particular satellite access station and stored in the satellite database.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention generally relates to communication systems and access control systems. More particularly, the invention relates to a method and system for controlling access to multiple target areas using a base station and at least one satellite access station, where the base station can be used to update data in the at least one satellite access station. 
     2. Background 
     Access control systems are used to limit access to target areas. Access control systems typically include an identification device that is capable of receiving input related to the identity of an individual, such as a unique code. The identification device determines whether an individual that corresponds to the input is authorized to enter the target area. If the input data, e.g., key code or input data, matches data that is prestored, the individual is allowed to enter the targeted area. For example, a lock on a door will unlock. 
     Access control systems are commonly used in private buildings, hotels, airports, banks and other secure locations. For example, in a hotel each room is equipped with a keycard reader. The reader controls access to the room and can unlock a door if the reader detects the proper authorization code on a keycard. The authorization codes are sent to the reader by the central controller. Typically, the codes will be sent to the reader when a guest checks in. The authorization codes are customized to a particular door or doors and to particular dates or times. Typically, one code is issued for each door for each authorized time period. 
     In the above described access control system the reader and the central controller are fixed in location and can be directly wired to each other. However, when a target area is a temporary area or a satellite environment, the locations of the target site are not fixed and, therefore, the same process to input or download information to the reader or identification devices cannot be used. 
     Management of access information and control information in satellite target sites are difficult because the satellite sites or target areas are not always connected or physically present at a central location. 
     There is a need for an efficient solution to track or restrict access in a satellite environment, which is part of an access control system. More particularly, there is a need to be able to efficiently update a satellite database with access rights, so that only authorized personnel will be allowed to enter the satellite facility where the access rights periodically change. 
     BRIEF SUMMARY OF THE INVENTION 
     Accordingly, disclosed is an access control system that can be used to protect multiple target sites, whether fixed or satellite, which are parts of an organization or facility. 
     Disclosed is an access control system comprising a base station located in a stationary target site used to control access to said stationary target site and a satellite access station coupled to a satellite target site used to control access to said satellite target site. The base station includes an identification device, storage device and a transceiver. The storage device includes a master database containing a list of access information. The satellite access station includes an identification device, a storage device, and a transceiver. The storage device includes a satellite site database containing a list of access information for the satellite target site. The master database contains a list of access information for each satellite access station. 
     Information contained in the master database for a particular satellite access station is provided to the particular satellite access station and stored in said satellite site database. 
     The information is provided to the particular satellite access station when the particular satellite access station is in close proximity to the base station. The base station transmits the information to the particular satellite access station. 
     The system further comprises an access card. The base station provides information related to a particular satellite access station to the access card, as an intermediary. When the access card is provided to the particular satellite access station, the information is detected by the particular satellite access station and selectively stored in the satellite site database. 
     Also disclosed is a method for configuring a satellite access device to control access to a satellite site. The method includes the steps of broadcasting periodically a position beacon of a base station, transmitting a signal from the satellite access device to the base station when the satellite access device receives the position beacon, authorizing the satellite access device using a unique identification code, and transmitting to the satellite access device updated access information for the satellite site. The information is only transmitted to the satellite access device if the device is authorized. The satellite access device updates a database with the information. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an access control system according to the first embodiment of the invention; 
         FIG. 2  is a block diagram of a base station according to the invention; 
         FIG. 3  is a block diagram of a satellite access station according to the invention; 
         FIG. 4  illustrates a flow diagram of a process of updating the satellite access station according to the first embodiment of the invention; 
         FIG. 5  illustrates an example of the first embodiment; 
         FIG. 6  illustrates an access control system according to the second embodiment of the invention; and 
         FIGS. 7   a  and  7   b  illustrate flow diagrams of a process of updating the satellite access station according to the second embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates an access control system, indicated generally by the number  1 , according to the present invention. The access control system  1  is an integrated access control system. The access control system  1  can control access to both stationary and mobile target areas. A stationary target site can be a building, an airport terminal, a subway station, stadium or arena. A mobile target site can be a moving vehicle, such as a company bus or an airport bus or a temporary site such as construction site. A fixed access station controls assess to a stationary target site. A satellite access station  110  controls access to a mobile target site. One of the fixed access stations is selected as a base station  100 . A base station  100  acts as a central control unit that coordinates the activities of all access units (fixed or satellite). The base station  100  will also act as an access control unit. 
     Each access station, fixed or satellite is attached to an entranceway of the target site. The satellite access station is typically located remote from the base station  100 . The satellite access station  110  can communicate with the base station  100 . 
       FIG. 2  illustrates a base station  100  according to the invention. The base station  100  includes an identification device  200 , an access device  210 , a control unit  220 , a memory section  230 , a server  240 , a transceiver  250  and a user interface  260 . 
     The identification device  200  acts as an input device and is used to identify a person. The identification device can be an access control reader, a card carder, a RFID reader, a biometric reader, a video base reader, a motion sensor or any other reader, which is capable of detecting a unique identity. The access device  210  is an output device that prevents or restricts entry. The access device  210  can be a magnetic or electric door contact or a turnstile. The control unit  220  controls the identification device  200  and access device  210 . The control unit  220  also controls and coordinates data exchange between base station, other fixed stations and the satellite access stations  110 . The control unit  220  is programmed with software for configuring, controlling, managing and commanding the access control system. The control unit  220  can be a microprocessor. 
     The memory section  230  is capable of storing user information, security credentials, access control permission levels, and unique identifications related to the satellite access stations  110 . The information is stored as a database. The term “database” is meant to encompass any type of data storage resource, regardless of how configured or organized. The security credentials will depend on the type of identification device  200 . For example, if the identification device  200  is a card reader, the security credential will be a passcode. However, if the identification device is a biometric reader, a biometric template will be stored in the memory section  230 . 
     The server  240  controls and manages all networking functions of the access control system  1 . The server  240  maintains a table containing a list of satellite access stations within the access control system  1  and its connection status. A connection status is connected or disconnected with the base station  100 . When a satellite access station  110  enters a communication range of the base station  100 , the satellite access station&#39;s status is connected. When a satellite access station  110  leaves the communication range of the base station  100  or is not in communication range, the connection status is disconnected. 
     A transceiver  250  is used to transmit and receive signals from the satellite access stations  110  and other fixed access stations. 
     The transceiver  250  can be a wired or wireless transceiver. The transceiver  250  will function in half duplex mode with the receiver off when the transmitter is on and vice versa. 
     The user interface  260  allows a person to manually enter the user information, security credentials, access control permission levels, and unique identifications into the base station  100  for storage. The user can enter the security credentials and access control permission levels for the base station  100  and all satellite access stations  110 . Alternatively, the security credentials and access control permission levels can be entered using the identification device  200  to avoid any manual input. The security credentials, and access control permission levels will be transmitted to the satellite access stations  110  using the transceiver  250 . 
     The user interface  260  can include a user input component such as a keypad, microphone, a touch screen and a personal computer. The user interface  260  can be a dedicated keypad co-located with the base station  100  or a workstation in communication with the base station  100 . 
       FIG. 3  illustrates a block diagram of a satellite access station  110  according to the invention. Many of the components of a satellite access station  110  and the base station  100  are similar and will not be described in detail again. The satellite access station  110  includes an identification device  300 , an access device  310 , a control unit  320 , memory section  330  and a transceiver  340 . The satellite access station  110  can optionally include user interface  350 . However, the identification device and access device does not have to be the same for the base station  100  and the satellite access stations  110 . For example, the base station  100  can use a card reader as the identification device  200  and the satellite access station  110  can use a fingerprint detector as the identification device  300 . Additionally, each satellite access station  110  can use a different identification device  300 . For example a first satellite access station  110  can use a fingerprint detector and a second satellite access station  110  can be a card reader. The type of identification device will depend on the level of security needed. Additionally, each satellite access station  110  can include more than one identification device  300 . 
     Each portion of the access control system  1  is configured to be integrated into a single access control system. This configuration process includes defining each portion of the access control system  1  as either a fixed or satellite access station, selecting a base station  100  from the fixed access station and installing the security management software into each station. Each station is also assigned a unique station identifier. The unique identifier is transmitted to the base station  100  to identity the station  100 . The unique identifier can be assigned at installation of the stations or when a station first communicates with the base station. The server  240  assigns the unique identifier. 
     The unique identifier is generated based upon the type of station, i.e., fixed or satellite. One of the fixed stations is selected to be the base station  100 . The selection of the base station  100  can be based upon the location of the station relative to the other fixed stations and potential satellite access stations  110 . 
     Once selected, the base station  100  is assigned a unique identifier and indicating that it is the base station  100  for the access control system  1 . The particular format for the unique identifier is dependent on the communication protocol. For all other stations besides the base station  100 , the unique identifier includes a site region number and a unique serial number used to identify the station within a site region. The target sites are grouped into regions, each region being identified by the site region number. The regions can be divided based upon zip codes, area codes, cities, states or countries. 
     The unique serial number can be assigned in serial, i.e., the first station is assigned 1, and the second station is assigned 2 and so forth. Alternatively, a random number can be assigned to a station using a random number generator. Once the server  240  assigns the unique identifier, the unique identifier is stored in a database in memory  230  and in the server  240 . 
     In one embodiment, this unique identifier is used as an address for sending data. For example, if the access control system uses IP protocol, the unique identifier can be an IP address, which is selected based upon the aforementioned criterion. Alternatively, a separate IP address can be assigned to each station and associated with the unique identifier. 
     During the configuration process, the base station transceiver  250  can be configured to adjust a power level of the signal to control the range of the signal. In operation, the transceiver  250  will periodically broadcast a signal. This signal will be a low power signal used by the satellite access stations  110  as a location beacon for the base station  100 . If the satellite access stations  110  detect the signal, i.e., receives the signal, the satellite access stations  110  know that they are within radio range of the base station  100 . 
       FIG. 4  illustrates a flow chart for the communication procedure between the base station  100  and the satellite access station  110  when the satellite access station is within radio range of the base station  100 . 
     At step  400 , upon receipt of the position beacon from the base station  100 , a satellite access station  110  transmits a unicast message indicating that the satellite access station  110  has entered radio range of the base station  100 . The message is a unicast message that can be received by the intended recipient, i.e., base station  100 . The “Entry” message will include the unique identifier for the satellite access station  110 . The unique identifier will be used as part of the authentication process. 
     The base station  100  will receive the “Entry” message and open the message. At step  405 , the server  240  will authenticate the satellite access station  110 . The server  240  will extract from the “Entry” message the unique identifier and match the unique identifier with a list of unique identifiers prestored in a database, step  410 . If no match is found, the process will end and the satellite access station  110  will not receive any updates (step  415 ). Optionally, the server  240  can generate a notification indicating an unauthorized access. In this case, the base station  100  can transmit a unicast message to the satellite access station  110  indicating that access is denied. 
     If the server  240  determines that the unique identifier matches one of the prestored identifiers, authentication is successful and the process proceeds to step  420 . The base station  100  will then transmit a unicast message to the satellite access station  110  acknowledging the satellite access station  110 . The server  240  will also update the status table for the particular satellite access station  110  to an “online” or “connected” status, step  425 . Once the connection is established the base station  100  will check to see if there are any pending data updates for the particular satellite access station  110 , at step  430 . A pending data update will be stored and indexed by the unique identifier in memory  230 . If there are no pending updates in memory  230 , the base station  100  will send a message to the satellite access station  110  indicating that there are no updates, at step  435 . Upon receipt of the “no update” message, the satellite access station  110  performs one of two functions. The satellite access station  110  can initiate a disconnection request or initiate a second update request, at step  436 . A second update request is used when the satellite access station  110  has pending updates, stored in its memory  330 , for the base station  100 . The disconnection request is initiated when there are no pending updates stored in memory  330  for the base station  100 . The pending updates stored in memory  330  can include information regarding individuals attempting to gain access to the target site, persons who gain access to the target site, time of access, all persons who left the target site and the time of departure. The disconnection process and the second update process will be described in detail later. 
     On the other hand, if there are pending data updates stored for the particular satellite access station  110 , the pending updates will be pushed to the satellite access station  110 , at step  450 . This will allow for the data at the satellite access station  110  and the base station  100  to be synchronized. The pending data update can include the latest access control data as well as software updates. The access control data might be new access rights for authorized persons or to remove expired access rights for persons that are no longer authorized. 
     The satellite access station  110  will update its memory  330  with the data update, at step  455 . Once the memory  330  updated, the satellite access station  110  can either initiate a disconnection process or a second update process, at step  436 . If the satellite access station  110  initiates the disconnection process, at step  436 , the satellite access station  110  transmits an “Exit” message to the base station  100 , at step  460 . The “Exit” message is an indication to the base station  100  that the satellite access station  110  has not pending updates and further communication is not needed. The base station  100  causes the server  240  to change the status table for the particular satellite access station  110  to “offline” or “disconnected”, at step  465 . 
     If, at step  436 , the satellite access station  110 , does not initiate a disconnection process, the second update process is initiated. The satellite access station  110  determines if the base station is still within communication range, at step  437 . This determination is based upon a reception of a position signal from the base station  100 . The position signal is similar to the location beacon described above. However, as describe above, the location beacon is broadcast to all satellite access stations  110 . The position signal does not need to be broadcast to every satellite access station  110 . The position signal can be a unicast message addressed only to any satellite access stations  110  that have a status of “online” or “connected”. The position signal is periodically sent. The period can be adjusted during installation. If the satellite access station  110  receives the position signal, the base station  100  and satellite access station  110  are still in communication range. The satellite access station  110  sends an acknowledgement signal to the base station  100 , at step  444  (ACK Signal). The ACK signal indicates that the satellite access station  110  has updates for the base station  100 . The base station  100  waits for the pending updates, at step  445 . At step  450 , the satellite access station  110  pushes the updates to the base station  100 , i.e., transmits the updates. Upon receipt of the updates from the satellite access station  110 , the base station  100  stores the update information in memory  230 . The information is added to the database in a record corresponding to the particular satellite access station  110 . The satellite access station identifier indexes the record. 
     After the update is stored, the satellite access station  110  can initiate the disconnection process, at step  436 . Optionally, in an embodiment, the base station  100  can transmit a confirmation message to the satellite access station  110  indicating that the update was successfully received and stored. 
     If, at step  437 , the satellite access station  110  does not receive the position signal, the satellite access station  110  waits for the position signal for a preset period of time, at step  438 . The preset period of time is adjusted and can be customized for a given system. For example, if the satellite access station  110  is protecting a moving vehicle, the period of time can be short, i.e., seconds. Additionally, the preset period of time can be related to the set interval for the location signal, e.g., three times the set interval. For example, if the position signal is transmitted every 20 seconds, the preset period of time can be one minute. The satellite access station  110  checks for the position signal for a predetermined number of times or until a predetermined “time out” has occurred, at step  439 . Afterwards, the satellite access station  110  will conclude that the base station  100  is out of range. If the satellite access station  110  does not receive the position signal within the time out period or the predetermined number of times has been received, a timeout occurs. 
     The base station  100  concludes that a “time out” has occurred if the base station does not receive an ACK signal within the “time out” period. The base station  100  changes the connection status of the satellite access station  110 , after a “time out”, step  465 . The server  240  updates the status table for the particular satellite access station  110  to “disconnected” or “offline”. Once the satellite access station  110  is offline, the satellite access station  110  independently operates to restrict access to a target area. 
     The above-identified method has been described with reference to communication between the base station  100  and a satellite access station  110 , however, a skilled artisan would appreciate that the same communication procedure can be used for communication between the base stations  100  and other fixed stations not selected to be the base station  100 . 
     All signal and messages transmitted by the access control system  1 , between the base station  100  and satellite access stations will be encrypted to secure communications against interception. 
     In one embodiment, the data can be encrypted using an Advanced Encryption Standard for high level security. A 256-bit strong encryption can be used. For medium level security a 128-bit strong encryption can be used. The type of encryption used can be determined depending on the security policy of the target site. Additionally, the type of encryption can depend on the communication protocol used. For example, if the stations are wireless and use BLUETOOTH standard, using short-range wireless links, BLUETOOTH standard includes encryption and decryption. Other types of encryption and decryption can be used such as a symmetric key known only to the satellite access stations  110  or public/private key pair. The encryption and decryption keys will be given to the satellite access stations  110  during configuration or initialization. 
       FIG. 5  illustrates an example of the invention.  FIG. 5  depicts a base station  100  (BS) located within a fixed target site  500 . The BS  100  has radio preset communication range  520  (R). A dashed line surrounding the BS  100  represents R. A satellite target  510  equipped with a satellite access station (SS)  110  is depicted as initially being located outside R. At time T 1  the satellite target moves within R and, therefore, can receive signals from the BS  100 , i.e., within proximity of the BS. The BS  100  periodically broadcasts the position beacon to let all satellite access stations  110  know the location of the BS  100 . For a given radio range, the BS  100  and SS  110  have a window of communication. As depicted in  FIG. 5 , the window of communication is the time period from T 1  to T 2 . The window depends on the velocity of the satellite target  510  and size of the R. The size of R can be adjusted to maximize the window of communication. For example, if the access control system  1  is monitoring high speed moving devices, the size of R would be increased. Alternatively, the transmission rate of the BS  100  and SS  111  can be controlled to insure that communication is completed with the window. Additionally, the frequency of the periodic position beacon can be increased to insure that the SS  110  receives the beacon shortly after the satellite target site  510  enters R. 
     Once in range, the SS  110  will receive the position beacon via the transceiver  340  and transmit the “Entry” message to the BS  100 . The BS will identify and authenticate the SS  110  using the unique identifier. After authentication, the server  240  will change the status of the SS  110  to “online” in the status table and transmit an acknowledge signal to the SS  110 . The BS  100  will check for pending data updates in memory  230  and send all pending updates for the SS  110  as an encrypted message to the SS  110 . Using a predetermined decryption key, the SS  110  will decrypt the message and update its memory. The fact that the SS  110  can decrypt the encrypted data update, using the predetermined decryption key insures that the data was received from the BS  100  and not from another source, e.g., a hacker. After updating memory, the SS  110  will transmit the “Exit” message to the BS  100  and the status table will be changed. 
     While the access control method has been described as first synchronizing data that is entered and stored at the base station  100  with the data stored in the satellite access stations  110  and then synchronizing the data entered and stored in the satellite access station  110 , the method can be reversed. Additionally, the method can be used only to update information either at the base station  100  or the satellite access station  110 . For example, when the satellite access station  110  enters the radio range of the base station  100 , the satellite access station  110  can transmit this data to the base station  100  such that the base station serves as a central repository for the access data. For example, the data can be transmitted to the base station  100 , once the satellite access station  110  has received the acknowledgement signal, i.e., after step  420 . 
       FIG. 1  illustrates the access control system  1  according to a first embodiment of the invention where the base station  100  communicates directly with the satellite access stations  110  to update the satellite access stations  110 . 
     In the second embodiment of the invention, the base station  100  can distribute data updates with the satellite access stations without establishing a direct connection between the satellite access stations  110  and the base station  100   
     For purposes of the description of the second embodiment, the same reference numbers for the base station  100  and satellite access stations  110  will be used. 
     The access control system  1  according to the second embodiment of the invention uses an access card  600  as an intermediary between the base station  100  and the satellite access stations  110 . The access card  600  can be a smart card, an RFID carder, a near field communication device, or any other access control card. The data update is copied from the base station  100  to the access card  600  from a card reader. The card reader will act as an identification device  200  as well as a writing device. The base station  100  of the second embodiment of the invention includes the same components as the base station  100  according to the first embodiment; however, the identification device includes at least one card reading device capable of reading and writing information from and to and access card  600 . 
     The base station  100  and satellite access stations  110  are configured and initialized in the same fashion as in the first embodiment. Each station is assigned a unique identifier, given an encryption and decryption key, and has security software installed. One of the stations is selected as the base station  100 . All of the unique identifier is stored in memory  230  in the base station  100 . Since a unique identifier identifies each station, access rights to each station can be individually entered and coordinated with each station using the unique identifier as an index. Each time new data is added to the system, it is indexed by the unique identifier and added to an information database. The base station  100  modifies the database to include the new information, e.g. adds access rights or deletes access rights, and adds the changes to a pending queue database indexed by the unique identifier. The pending Queue database is used by the base station  100  to determine if there are any data updates to be sent to a satellite access station  110   
     Data can only be copied to access cards that are authorized to access the satellite target site. In other words, only access cards  600  having an authorized access code will have any data update writing to the card. 
       FIGS. 7   a  and  7   b  illustrate a control method according to the second embodiment of the invention.  FIG. 7   a  illustrates steps that occur at the base station  100  and  FIG. 7   b  illustrates steps that occur at the satellite access station  110 . 
     At step  700 , the base station  100  determines if the access card  600  is authorized to receive any updates. The access card  600  is read by identification device  200 . The identification device  200  determines the access code and the particular satellite access station(s) to which the access code corresponds. The same access code can be used to access multiple satellite target sites through different satellite access stations  110 . The base station  100  searches the database, in memory  230 , for the determined access code and satellite access station  110 . If the access card  600  is authorized for at least a satellite target site, i.e., at least one satellite access station  110 , the base station  100  will then determine if there are any pending data updates in the pending queue database, at step  710 . If the access card  600  is authorized for more than one satellite access stations  110 , the base station  100  will look for data updated for each satellite access station  110 . If the access card  600  is not authorized for any satellite access station  110 , the base station  100  will not perform the search. 
     If there are no updates, then the update process ends. Optionally, the base station  100  can notify the operator that there are no updates. 
     If there are updates, the base station  100 , using a predetermined encryption key, at step  720 , will encrypt the data updates. The encrypted data update is “written” to the access card  600 , at step  730 . The manner in which the data updates are written to the access card will depend on the type of card. For example, the data update can consist of encrypted numbers that have been magnetically written onto a normal magnet swipe card. Alternatively, the update data can consist of encrypted data that is stored in a memory section of the record devices. If a different encryption key is used to encrypt the data update, the base station  100  can also write or store the encryption key on the access card  600 . 
     The access card  600  is then transferred to the satellite access station  110   n  and read by an identification device  300 , at step  750 . The data stored or written on the access card  600  will be “dumped” to the identification device  300 . The satellite access station  110   n  will decrypt the data, at step  755 , using either a preset decryption key stored in memory or the new decryption key encoded in the access card  600 . 
     After all of the data is decrypted, the satellite access station  110   n  determines if there is any data update, at step  760 . If there is no update data, the identification device  300  will determine if the identification encoded in the access card  600  is authorized, i.e., matched an identification prestored in memory, at step  765 . If there is a match, at step  765 , access will be granted at step  770 . If there is no match, access will be denied at step  775 . 
     If at step  760 , the satellite access station  110  determines that there is data update, then the identification device  300  will determine if the satellite access station  110  already received the data update from another access card  600  or directly from the base station  100 . Only the first time that the update data is detected and received, is the data stored in memory and added to the database. Each successive time, the update data is ignored. Multiple access cards  600  can contain the same data update. 
     If the data update is already added, the identification device  300  will proceed to the access control process, i.e., steps  765 - 775 . 
     If the data update has not been added, the satellite access station  110   n  device  300  will cause the update data to be stored in memory and added to the database. After the data is added, the identification device  300  will proceed to the access process, i.e., steps  765 - 775 . 
     According to the second embodiment, the access information can be synchronized in both the satellite access stations  110  and the base station  100  without having a direct connection between them. 
     While the first and second embodiments have been described separately, a combination of the two can be used. For example, when the satellite access stations  110  are in radio range of the base station  100  the first embodiment can be used. However, if the satellite access stations  110  and their corresponding satellite devices are not in radio range, the second embodiment can be used such that the satellite access stations  110  can always receive the update data. 
     The invention has been described herein with reference to a particular exemplary embodiment. Certain alterations and modifications may be apparent to those skilled in the art, without departing from the scope of the invention. The exemplary embodiments are meant to be illustrative, not limiting of the scope of the invention, which is defined by the appended claims.