Abstract:
A data communications network comprises a plurality of geographically spaced wireless transmitters each for transmitting a different network address. At least one mobile user terminal has a wireless receiver for receiving the network addresses transmitted by the transmitters, a wireless transmitter for transmitting requests for delivery of data files from remote locations identified by the network addresses, a wireless receiver for receiving from the remote location the data files identified by the network addresses, and output means for outputting the data files received. Preferably, the network addresses each comprise a Uniform Resource Locator and the data files each comprise a World Wide Web page.

Description:
TECHNICAL FIELD 
     The present invention relates to an apparatus and method for accessing a data file via a data communication network. 
     BACKGROUND OF THE INVENTION 
     In recent years, there has been explosive growth in the Internet, and in particular of the WorldWide Web (WWW), which is one of the facilities provided via the Internet. The WWW comprises many pages or files of information, distributed across many different servers. Each page is identified by an individual address or “Uniform Resource Locator (URL)”. Each URL denotes both a server machine, and a particular file or page on that machine. There may be many pages or URLs resident on a single server. 
     Typically, to utilise the WWW, a user runs a computer program called a Web browser on a client computer system such as a personal computer. Examples of widely available Web browsers include the “WebExplorer” Web browser provided by International Business Machines Corporation in the OS/2® Operating System software, or the “Navigator” Web browser available from Netscape Communications Corporation. (“OS/2” is a registered trademark of International Business Machines Corporation.) The user interacts with the Web browser to select a particular URL. The interaction causes the browser to send a request for the page or file identified in the selected URL to the server identified in the selected URL. Typically, the server responds to the request by retrieving the requested page, and transmitting the data for that page back to the requesting client. The client-server interaction is usually performed in accordance with a protocol called the Hypertext Transfer Protocol (“HTTP”). The page received by the client is then displayed to the user on a display screen of the client. The client may also cause the server to launch an application, for example to search for WWW pages relating to particular topics. 
     WWW pages are typically formatted in accordance with a computer programming language known as Hypertext Mark-up Language (“HTML”). Thus a typical WWW page includes text together with embedded formatting commands, referred to as tags, that can be employed to control for example font style, font size, lay-out etc. The Web browser parses the HTML script in order to display the text in accordance with the specified format. In addition, an HTML page also contain a reference, in terms of another URL, to a portion of multimedia data such as an image, video segment, or audio file. The Web Browser responds to such a reference by retrieving and displaying or playing the multimedia data. Alternatively, the multimedia data may reside on its own WWW page, without surrounding HTML text. 
     Most WWW pages also contain one or more references to other WWW pages, which need not reside on the same server as the original page. Such references may be activated by the user selecting particular locations on the screen, typically by clicking a mouse control button. These references or locations are known as hyperlinks, and are typically flagged by the Web browser in a particular manner. For example, any text associated with a hyperlink may be displayed in a different colour. If a user selects the hyperlinked text, then the referenced page is retrieved and replaces the currently displayed page. 
     Further information about HTML and the WWW can be found in “World Wide Web and HTML” by Douglas McArthur, p18-26 in Dr Dobbs Journal, December 1994, and in “The HTML SourceBook” by Ian Graham, John Wiley, N.Y., 1995. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, there is now provided a data communications network comprising: a plurality of geographically spaced wireless transmitters each for transmitting a different network address, and, at least one mobile user terminal having a wireless receiver for receiving the network addresses transmitted by the transmitters, a wireless transmitter for transmitting requests for delivery of data files from remote locations identified by the network addresses, a wireless receiver for receiving from the remote location the data files identified by the network addresses, and output means for outputting the data files received to a user. 
     Preferably, the network addresses each comprise a Uniform Resource Locator and the data files each comprise a World Wide Web page. 
     In preferred embodiments of the present invention, the network comprises a plurality of geographically spaced base stations each comprising a receiver for receiving the requests for delivery transmitted by each remote user terminal and for forwarding the requests for delivery to the remote locations identified by the network addresses via the Internet. 
     In use, each transmitter may continuously transmit the network address. Alteratively, in use, each transmitter may transmit the network address on detection of an interrogation signal generated by each user terminal. 
     The output means may comprise a display device for displaying the data files received. Furthermore, the output means may comprise an audio output device for generating an audio output as a function of the data files received. 
     Viewing the present invention from another aspect there is now provided a method of accessing a data file in a data communications network, the method comprising: transmitting, by wireless communications, a different network address from each of a plurality of geographically spaced wireless transmitters; receiving, in a mobile user terminal, by wireless communications, the network addresses transmitted by the transmitters; transmitting from the mobile user terminal, by wireless communications, requests for delivery of data files from remote locations identified by the network addresses; receiving, by wireless communications, in the user terminal, the data files identified by the network addresses from the remote locations; and, outputting, by the user terminal, the data files received. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
     FIG. 1 is a block diagram of a data communications network; 
     FIG. 2 is a block diagram of a base station server computer system of the data communications network; 
     FIG. 3 is a block diagram of a WWW server computer system as the data communications network; 
     FIG. 4 is a block diagram of a user terminal of the data communications network; and, 
     FIG. 5 is a block diagram of a tagging device of the data communications network. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring first to FIG. 1, a data communication network embodying the present invention comprises the Internet  10  and a wireless network  60 . The wireless network  60  comprises a plurality of geographically divided cells  61 - 63  (shown as elements  61   a  and  61   b ,  62   a  and  62   b , and  63   a  and  63   b ) of substantially equal area, a plurality of geographically spaced transmitters  80 - 130 , and a plurality of base station computer systems  50 - 52 . Each base station  50 - 52  is located in a different cell  61 - 63 . Each cell  61 - 63  comprises a different group of the transmitters  80 - 130 . Each cell  61 - 63  is geographically divided into a plurality of sub-cells  61   a   61   b . Each transmitter  80 - 130  of each group of transmitters  80 - 130  is located in a different sub-cell  61   a - 61   b . Each base station  50 - 52  of the wireless network  60  is connected to the Internet  10 . Also connected to the Internet are a plurality of WWW server computer systems  2040 . The wireless network  60  further comprises a user terminal  70 . 
     Referring now to FIG. 2, each base station  50 - 52  comprises a random access memory (RAM)  210 , a read only storage (ROS) or memory (ROM)  220 , a central processing unit (CPU)  200 , a mass storage device  230  comprising one or more large capacity magnetic disks or similar data recording media, a network adapter  240 , a keyboard adapter  260 , a pointing device adapter  250 , a display adapter  270 , and a radio frequency (RF) transceiver  290 , all interconnected via a bus architecture  280 . A keyboard  310  is coupled to the bus architecture  280  via the keyboard adapter  260 . Similarly, a pointing device  300 , such as a mouse, touch screen, tablet, tracker ball or the like, is coupled to the bus architecture  280  via the pointing device adapter  250 . Equally, a display output device  320 , such as a cathode ray tube (CRT) display, liquid crystal display (LCD) panel, or the like, is coupled to the bus architecture  280  via the display adapter  270 . The RF transceiver  290  has sufficient range for RF communications with the user terminal  70  only when the user terminal  70  is located within the same cell  61 - 63 . 
     Basic input output system (BIOS) software is stored in the ROM  220  for enabling data communications between the CPU  200 , mass storage  230 , RAM  210 , ROM  220 , adapters  240 - 270 , and the wireless data link  290  via the bus architecture  280 . Stored on the mass storage device  230  is operating system software and application software. The operating system software cooperates with the BIOS software in permitting control of the base station  50  by the application software. The application software includes communications software for enabling communication of data between the WWW servers  2040  and the base stations  50 - 52  via the network adapter  240  and the Internet  10 , and between the user terminal  70  and the base stations  5052  via the wireless link  290 . 
     Referring now to FIG. 3, each WWW server  20 - 40  comprises a RAM  340 , a ROM  350 , a CPU  330 , a mass storage device  360  comprising one or more large capacity magnetic disks or similar data recording media, a network adapter  380 , a keyboard adapter  335 , a pointing device adapter  390 , and a display adapter  345  all interconnected via a bus architecture  370 . A keyboard  375  is coupled to the bus architecture  370  via the keyboard adapter  335 . Similarly, a pointing device  365 , such as a mouse, touch screen, tablet, tracker ball or the like, is coupled to the bus architecture  370  via the pointing device adapter  390 . Equally, a display output device  385 , such as a CRT display, LCD panel, or the like, is coupled to the bus architecture  370  via the display adapter  345 . 
     BIOS software is stored in the ROM  350  for enabling data communications between the CPU  330 , mass storage  360 , RAM  340 , ROM  350 , and adapters  380 ,  390 ,  335 , and  345  via the bus architecture  370 . Stored on the mass storage device  360  is operating system software and application software. The operating system software cooperates with the BIOS software in permitting control of the server  20 - 40  by the application software. The application software includes communications software for enabling communication of data between the server  20 - 40  and the base stations  50 - 52  via the network adapter  380  and the Internet  10 . Also stored on the mass storage device  360  is a WWW page.  360 , RAM  340 , ROM  350 , and adaptors  380 ,  390 ,  335 , and  345  via the bus architecture  370 . Stored on the mass storage device  360  is operating system software and application software. The operating system software cooperates with the BIOS software in permitting control of the server  20 - 40  by the application software. The application software includes communications software for enabling communication of data between the server  20 - 40  and the base stations  50 - 52  via the network adapter  380  and the Internet  10 . Also stored on the mass,storage device  360  is a WWW page. 
     Referring now to FIG. 4, the user terminal  70  comprises a CPU  400 , a RAM  410 , a ROM  420 , a user input  460 , a display  470 , an RF receiver  450 , and an RF transceiver  430  all interconnected by a bus architecture  440 . The RF transceiver  430  is tuned for RF communications with the base stations  50 - 52 . The RF transceiver  430  only has sufficient range for RF communications with the RF transceiver  290  of the base station  50 - 52  in the same cell  61 - 63  as the user terminal  70 . The RF receiver  450  is tuned to receive RF signals from the transmitters  80 - 130 . The RF receiver  450  has sufficient sensitivity to receive RF signals from the transmitter located in the same sub-cell  61   a - 61   b  as the user terminal  70 . The display  470  comprises a flat panel display such as an LCD panel and the user input  460  comprises a touch sensitive screen overlaying the flat panel, display for actuation by a stylus, finger or the like. In other embodiments of the present invention, the user input  460  may comprise a different form of input transducer, such as a keyboard for example. 
     BIOS software is stored in the ROM  420  for enabling data communications between the CPU  400 , RAM  410 , ROM  420 , display  470 , user input  460 , receiver  450 , and transceiver  430  via the bus architecture  440 . Also stored in the ROM  420  is operating system software and application software. The operating system software cooperates with the BIOS software in permitting control of the user terminal  70  by the application software. The application software comprises a web browser for accessing, via the transceiver  430 , the base stations  50 - 52 , and the Internet  10 , WWW pages stored on WWW servers  20 - 40  and for displaying WWW pages read from the WWW servers  2040  on the display screen  470 . The application software also includes communication software for reading, via the receiver  450 , data from the transmitters  80 - 130  and for supplying, via the transceiver  430 , data read from the transmitters  80 - 130  to the base stations  50 - 52 . 
     Referring now to FIG. 5, each of transmitters  80 - 130  comprises a data store  500 ,. control logic  510  and an RF transmitter  520  all interconnected by a bus architecture  530 . The data store  500  contains a URL identifying one of the WWW pages stored on WWW servers  20 - 40 . The RF transmitter  520  is tuned to transmit RF signals for reception by the receiver  450  of the user terminal  70 . The RF signals transmitted by the RF transmitter  520  have sufficient power to enable reception by the receiver  450  of the user terminal  70  when the user terminal  70  is located within the same sub-cell  61   a - 61   b . The data store  500  of each of the transmitters  80 - 130  contains a different URL. 
     In operation, the RF transmitter  520  of each of the transmitters  80 - 130  continuously transmits, under control of the logic  510 , an RF signal containing the URL stored in the data store  500 . When the user terminal  70  passes into a sub cell,  61   a  say, the receiver  450  detects the RF signal transmitted by the transmitter  80  located in the sub-cell  61   a . The receiver  450  thus receives the URL stored in the data store  500  of the transmitter  80 . The CPU  400  activates the web browser and inputs the received URL. The web browser instructs the CPU  400  to communicate, via the transceiver  430 , the received URL to the base station  50  located in the same cell  61 . The wireless data link  290  of the base station  50  receives the URL from the user terminal  70 . The base station  50  retrieves the WWW page specified by the received URL from the associated WWW server  20  to  40  via the Internet  10 . The WWW page obtained from the Internet  10  is sent by the base station  50  to the user terminal  70  via the transceiver  290 . The user terminal  70  then displays the received WWW page to the user of the display screen  470 . In some embodiments of the present invention, the user terminal may comprise an audio output device for generating an audio output as a function of the received WWW page. 
     When the user terminal  70  passes from, say, sub-cell  61   a  to sub-cell  61   b , the receiver  450  begins detecting an RF signal containing a new URL. The new URL is the URL stored in the transmitter  90  located in sub-cell  61   b . The CPU  400  inputs the received new URL to the web browser. The web browser instructs the CPU  400  to communicate, via the transceiver  430 , the received new URL to the base station  50  located in the same cell  61 . The wireless data link  290  of the base station  50  receives the new URL from the user terminal  70 . The base station  50  retrieves the new WWW page specified by the received new URL from the associated WWW server  20  to  40  via the Internet  10 . The new WWW page obtained from the Internet  10  is sent by the base station  50  to the user terminal  70  via the transceiver  290 . The user terminal  70  then displays the received new WWW page to the user of the display screen  470 . 
     When the user terminal  70  passes from, say, sub-cell  61   b  to sub-cell  62   a , the receiver  450  begins detecting an RF signal containing another new URL. The new URL is the URL stored in the transmitter  100  located in sub-cell  62   a . The CPU  400  again inputs the received new URL to the web browser. The web browser instructs the CPU  400  to communicate, via the transceiver  430 , the received new URL to the base station  51  located in the same cell  62 . The wireless data link  290  of the base station  51  receives the new URL from the user terminal  70 . The base station  51  retrieves the new WWW page specified by the received new URL from the associated WWW server  20  to  40  via the Internet  10 . The new WWW page obtained from the Internet  10  is sent by the base station  50  to the user terminal  70  via the transceiver  290 . The user terminal  70  then displays the received new WWW page to the user of the display screen  470 . 
     In a preferred application of the embodiment of the present invention hereinbefore described, the user terminal  70  is mounted within a vehicle such as a car, motorcycle, or lorry (i.e. truck), and the transmitters  80 - 130  are located at intervals throughout a road transportation system. Each of the WWW pages stored on servers  2040  contains travel information relating to the geographical area covered by the sub-cell of the wireless network  60  containing the transmitter  80 - 130  in which the corresponding URL is stored. Thus, as the vehicle passes into one of a plurality of sub-cells, the corresponding WWW page containing information relevant to the associated geographical area is automatically down-loaded into the web browser of the user terminal  70 . The information may include one or more of the following: traffic reports; travel directions; weather conditions; parking availability; and, local attractions such as museums, zoos, art galleries and the like. It will be appreciated that a plurality of vehicles travelling within the same transportation system may each be fitted with examples of the user terminal  70  hereinbefore described. 
     In the preferred embodiment of the present invention hereinbefore described, each transmitter  80 - 130  continuously transmits the URL stored in it. However, in other embodiments of the present invention, each transmitter  80 - 130  may instead transmit the URL on command. For example, in some embodiments of the present invention, each transmitter  80 - 130  may transmit the URL on detection of an RF interrogation signal transmitted by the user terminal  70  when it passes into the relevant sub-cell. In other embodiments of the present invention, the interrogation signal activating each of the transmitters  80 - 130  may be generated independently of the user terminal  70 . For example, the interrogation signal may be generated by a separate RF emitter mounted remotely from the user terminal  70  in the same vehicle. The interrogation signal may be generated automatically as a function of time or distance travelled, or both. Alternatively, the interrogation signal may be selectively generated according to instructions from the user entered via user input  460  for example. It will be appreciated that, in some embodiments of the present invention, the transmitter  80 - 130  may be activated by a pressure switch mounted in the carriage way (i.e. road) on which a vehicle carrying the user terminal  70  travels. 
     In some embodiments of the present invention, the sub-cells may cover substantially equal geographical areas. However, in particularly preferred embodiments of the present invention, the sub-cells cover geographical areas of different sizes, with a greater density of transmitters  80 - 130  disposed in more densely populated areas where more frequent updates of detailed travel information are desirable. 
     It will be appreciated that the embodiments of the present invention enable information in general, and travel information in particular, to be supplied to mobile users quickly and efficiently. Furthermore, the servers enable the information to be updated conveniently for immediate supply to remote users.