Abstract:
A secure communication channel is established between a portable computing device and a fixed public network outlet. Infrared beaming is employed wherein the IR beam is confined to an optical fiber placed between the IR beaming ports of the portable device and the fixed outlet. A portable computing device such as a PDA or a laptop PC has an infrared beaming port capable of bidirectional serial communication. A fiber optic system includes an optical fiber, a retractable spool for retaining the optical fiber, a fiber mount for mounting a first end of the optical fiber in alignment with the infrared beaming port of the portable computing device, and a terminator at a second end of the optical fiber. A public network outlet is provided in a fixed location and has an infrared data port in communication with an optical fiber connector adapted to receive the terminator. The infrared data port is in bidirectional serial communication with the infrared beaming port in order to authenticate the portable computing device and to provide public network services in response to the authentication.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   Not Applicable. 
   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
   Not Applicable. 
   BACKGROUND OF THE INVENTION 
   The present invention relates in general to the connection and use of mobile computing devices with a fixed public network interface, and, more specifically, to obtaining a secure network connection using a fiber optic system. 
   Many people, such as travelers, are becoming increasingly reliant upon their mobile (i.e., portable) computing devices for many day-to-day tasks. Examples of portable computing devices include laptop computers and personal digital assistants (PDA&#39;s). Typical tasks include establishing and/or managing personal communications (e.g., telephone and electronic mail), conducting transactions (e.g., making reservations and paying by credit card), managing a schedule or calendar, monitoring financial information, and obtaining news and weather information, to name just a few. 
   When away from a home or office connection, it may often be desired to interface a personal portable device with a fixed outlet into a network such as 1) the public switched telephone network (PSTN) at a payphone or other telephone station to engage in a voice telephone call or 2) a computer data network (e.g., a wide area network, or WAN, connection to the Internet) at a public data terminal or kiosk to engage in computer networking applications such as e-mail. Use of such a fixed network outlet typically involves the use of personal, confidential information which may be transmitted from the personal computing device during use. For example, a phone card number and a personal identification number (PIN) or a credit card number may be used in establishing a pay telephone call (e.g., a long distance call). A private contact list may be consulted to determined a called telephone number. Computer network usernames and passwords may be accessed in launching the desired computer network applications. 
   The privacy of personal information transmitted by the portable computing devices may be compromised by thieves who actively attempt to obtain the information using various kinds of surveillance and eavesdropping. For example, when information from a PDA or a traditional telephone calling card such as a telephone card number and PIN are entered manually on a telephone keypad, thieves have been known to videotape the keypad entries. 
   A wireless RF link between a portable device and a fixed station can avoid the visible display of personal information that might be videotaped, but the RF communication signals radiate throughout an uncontrolled area around the device and are subject to being intercepted by thieves. The RF signals can be encrypted, but that requires coordination (e.g., exchange of secret keys) between the sender and receiver, which is often not practical for a public network outlet that is intended to provide service to any requesting device. In this situation, the encryption keys would have to be exchanged in the same unsecured manner and could be intercepted and used by the information thieves using a “man in the middle” ploy or other techniques. 
   Both PDA&#39;s and laptop computers are typically provided with an infrared (IR) beaming port for achieving serial communication using one of the IrDA standards of the Infrared Data Association. The IR beam for such a beaming operation spreads over a defined angular region to ensure that the desired receiver is illuminated by the IR beam. However, there is substantial spillage beyond the intended receiver which makes it possible for thieves to intercept the transmitted data when used in a public place. 
   SUMMARY OF THE INVENTION 
   The present invention has the advantage of enabling a secure communication channel between a portable computing device and a fixed public network outlet. Infrared beaming is employed wherein the IR beam is confined to an optical fiber placed between the IR beaming ports of the portable device and the fixed outlet. The invention obtains a low cost of hardware by using available IR beaming components which are both reliable and inexpensive. A cheaply-produced optical fiber having relatively low optical performance can be employed due to the short distance involved. 
   In one aspect of the invention, a secure communication system is provided. A portable computing device has an infrared beaming port capable of bidirectional serial communication. A fiber optic system includes an optical fiber, a retractable spool for retaining the optical fiber, a fiber mount for mounting a first end of the optical fiber in alignment with the infrared beaming port of the portable computing device, and a terminator at a second end of the optical fiber. A public network outlet is provided in a fixed location and has an infrared data port in communication with an optical fiber connector adapted to receive the terminator. The infrared data port is in bidirectional serial communication with the infrared beaming port in order to authenticate the portable computing device and to provide public network services in response to the authentication. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block, schematic diagram showing one embodiment of the overall system of the present invention. 
       FIG. 2  is a top cross-sectional view of a first embodiment for deploying an optical fiber in alignment with an IR transceiver. 
       FIG. 3  is a top cross-sectional view of an embodiment for deploying a pair of optical fibers in alignment with an IR transceiver on the interior of a portable computing device. 
       FIG. 4  is a side cross-sectional view of an embodiment having a single optical fiber on the interior of the portable computing device and an exterior shutter. 
       FIG. 5  is a top cross-sectional view of another embodiment for deploying an optical fiber on the interior of a portable computing device. 
       FIG. 6  is a side cross-sectional view taken along line  6 - 6  of  FIG. 5 . 
       FIG. 7  is a side cross-sectional view of a spool of the present invention. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   Referring to  FIG. 1 , a portable computing device  10  is shown as a personal digital assistant (PDA) or personal information device (PID), but could also be comprised of any other handheld device, tablet, laptop PC, or mobile computing device. A fixed network outlet  11  makes a network connection available to a public switched telephone network (PSTN)  12  and/or a data network  13  such as a wide area network (WAN) which may include the Internet. Outlet  11  may be constructed as part of a payphone or an Internet kiosk, for example, which is located in a public place such as an airport terminal, hotel, shopping mall, or other publicly accessible area. 
   PDA  10  is shown as a conventional unit including an IR beaming port  14  which is capable of serial communications in conformance with standards and protocols defined by the Infrared Data Association (IrDA). IR transmission/reception pulses to/from an IrDA transceiver extend in a cone which may have a width in the range of about 30° to about 60° and should have an effective range in open air of about 1 meter. Rather than radiating through open air, however, the present invention blocks open air radiation and routes the IR pulses through an optical fiber which cannot be intercepted by a third party. In the embodiment of  FIG. 1 , an accessory  15  comprises a fiber optic system which is releasably attached to PDA  10  (e.g., by sliding-on in the direction of attachment arrow A). An optical fiber  16  is partially wound on a retractable spool  17  which is housed within a sleeve member  18 . A fiber mount  19  holds a first end  20  of optical fiber  16  in a fixed position within sleeve member  18 . Sleeve member  18  conforms to the shape of PDA  10  and when joined to PDA  10  (e.g., by sliding, snapping-on, or other means of releasable attachment), first end  20  of optical fiber  16  is held in alignment with IR beaming port  14 . 
   Optical fiber  16  exits sleeve member  18  via an aperture  21  and has a second end having a terminator for coupling to fixed outlet  11 . Spool  17  pays out optical fiber  16  to provide a desired length of optical fiber  16  to reach outlet  11 . Spool  17  may use a conventional spool retractor mechanism so that a desired length can be locked in place during use and subsequently retracted (e.g., by a quick tug on fiber  16  similar to operation of a window shade). Depending upon the optical quality (i.e., losses) of optical fiber  16 , it may be possible for the total length of optical fiber  16  to exceed one meter. 
   Optical fiber  16  extends from sleeve member  18  through an aperture  21 . The terminator may include a ferrule  22  with a grasping collar  23  at its distal end whereby the second end of optical fiber  16  passes through ferrule  22  and collar  23  to an exposed end for transferring IR radiation. Aperture  21  may be sized to accommodate ferrule  22  to allow collar  23  to abut the exterior surface of sleeve member  18  when retracted. By keeping the tolerance of aperture  21  around optical fiber  16  small and/or by arranging the interior components so that there is no open path directly between IR beaming port  14  and aperture  21 , there is no significant leakage of IR radiation through aperture  21 . A gasket or shroud can also be provided to block any leakage. 
   Fixed outlet  11  includes an optical fiber connector  25  for receiving the second end of optical fiber  16 . An environmental cover  26  such as a hinged doorway protects a receptacle  27  when not in use and opens upon insertion of collar  23  so that it may be connected to receptacle  27 . At least a portion of receptacle  27  is transparent to IR radiation so that when collar  23  is retained in receptacle  27 , optical fiber  16  is aligned with an IrDA transceiver  28  which provides an IR data port of outlet  11 . Transceiver  28  is connected to a controller/interface block  30  which may be comprised of a microcontroller, one or more digital signal processors (DSP&#39;s), an application specific integrated circuit (ASIC), or a combination of these. Block  30  interfaces the data streams between portable device  10  and the telephone system and/or between portable device  10  and the computer data network. Although fixed outlet  11  is shown having network access to both a telephone system and a data network, the invention can also be used with either type of network access alone. 
   Fixed outlet  11  includes telephone equipment  31  (e.g., a handset, a ringer, and a dialing circuit) connected to control block  30 . A dual-tone multi-frequency (DTMF) generator  32  is connected to phone  31  and to control block  30 . In order to transfer call set-up information such as a dialed telephone number, telephone card number, and PIN number to phone  31 , a software application executing in PDA  10  is activated by the user to transmit or “beam” the desired data via the fiber optic system to transceiver  28 . An encoded digital data stream from transceiver  28  is decoded in control block  30  and a corresponding software application uses the decoded data to control a phone call via DTMF generator  32 . For example, control block  30  may take phone  31  off-hook (or the handset may be manually taken off hook by the user) and then a telephone number sent from PDA  10  is dialed by causing the appropriate DTMF tones to be generated in sequence. Then the user may initiate an action on PDA  10  for supplying a phone card number and/or PIN number after PSTN  12  has given a voice prompt to request the information (e.g., PSTN  12  includes an IVR or intelligent voice response unit for receiving DTMF tones and performing desired actions within PSTN  12 ). 
   Fixed outlet  11  further includes equipment to interface with a data network such as a data modem  33  connected to control block  30 . Alternatively, another wideband network gateway or a dial-up interface could be provided. In an alternative embodiment using DSL (not shown), a shared telephone line to PSTN  12  and WAN  13  is employed (with highpass and lowpass filters to separate voice and data traffic) as is known in the art. Conventional software programs can also be used to provide the necessary functionality of PDA  10  and outlet  11  to generate and receive the desired computer data and to encode and decode signals for IrDA transmission. 
   Because portable device  10  is not a known or trusted device within a particular data network being accessed, an authentication, authorization, and accounting (AAA) server  34  is connected within WAN  13  to control the data network access via fixed outlet  11 . AAA server  34  interacts with access and gateway servers in a conventional manner (e.g., using RADIUS) to obtain identification and billing information from a user. Thus, fixed outlet  11  acts as a pass-through link to the data network that is blocked by an access router on the WAN side of the data connection until appropriate authentication, authorization, and accounting functions have been performed by the user. 
   Details of the fiber optic system are shown in greater detail in  FIGS. 2-7 . As shown in  FIG. 2 , PDA  10  includes a lower shell portion  40  having an opening for retaining an IR-transmissive window  41 . An IrDA-compliant transceiver  42  is mounted to a printed circuit board  43  which preferably also contains other electronic components (not shown) such as a microprocessor, an IrDA encoder/decoder, a power supply, and others. Transceiver  42  may, for example, be comprised of an HSDL-2300 Infrared IrDA Compliant 4 Mb/s 3.3 V Transceiver available from Agilent Technologies, Inc., of Palo Alto, Calif. 
   The slip-on fiber optic accessory (only partially shown) locates end  20  of optical fiber  16  in alignment with transceiver  42  by means of fiber mount  19 . End  20  is preferably kept as close to window  41  as possible in order to maximize its apparent angular size as seen from transceiver  42  (while staying within the radiation cones of the transmitter and receiver portions), thereby maximizing the amount of IR radiation coupled into optical fiber  16 . 
   As shown in  FIG. 3 , the fiber optic system can be incorporated into the portable computing device. Thus, transceiver  42  is backed off slightly from window  41  to accommodate optical fiber  16 . Due to the closer proximity of optical fiber  16  to the transceiver lenses, it becomes more difficult to locate the end of the optical fiber within the radiation cones of both the emitter and the receiver. Therefore, optical fiber  16  may comprise a first optical fiber element  46  and a second optical fiber element  47 , each comprising a distinct fiber and the two distinct fibers are preferably joined along their lengths to provide a flexible cable. The first ends of optical fiber elements  46  and  47  are mounted in place by a mounting block  48 , the elements being aligned with a respective one of the transceiver lenses. The second ends of elements  46  and  47  are preferably retained within ferrule  22  and collar  23  in relationship to a reference position (i.e., keyed) so that the position of elements  46  and  47  can be determined when connecting to the receptacle of a fixed network outlet. Preferably, the first element is aligned with the infrared transmitter of transceiver  42  at its first end and with the infrared receiver of the fixed network outlet at its second end, and the second element is aligned with the infrared receiver of transceiver  42  at the first end and the infrared transmitter of the fixed network outlet at its second end. 
   The integrated embodiment of  FIG. 3  has spool  45  mounted in the interior of PDA  10  with optical fiber  16  passing through an aperture  49  in shell  40 . 
   Using an integrated fiber optic system, it may be desirable to maintain the capability of IR beaming through open air (i.e., without using the fiber optic system). Therefore, optical fiber  16  is preferably positioned to intercept only a portion of the radiation cones of the IR transceiver in order to allow a further portion of the cones to penetrate window  41 .  FIG. 4  shows a side view of an embodiment using a single optical fiber which intercepts a lower portion of the radiation cones within the interior of the portable computing device. When the fiber optic system is being used, it is preferable to block the open air radiation of IR so that it cannot be intercepted by third parties. Therefore, a slidable shutter or curtain  50  is affixed to an outer covering of the portable computing device to selectably cover window  41 . Shutter  50  may slide along retention slots (not shown), may be elastically deformed between open and closed positions, or may use any other suitable mechanism. 
     FIG. 5  shows an alternative embodiment with an internal shutter  51  that is slidable along with end  20  of optical fiber  16 . A base  52  includes a slot  53  for guiding moveable shutter  51  between an open-air beaming position (shown in solid lines) and a fiber-optic beaming position (shown in dashed lines). A push lever  54  extending from shutter  51  through a slot  55  in shell  40  allows either position to be manually selected. As shown by cross section in  FIG. 6 , end  20  of the optical fiber can be more directly aligned with the lenses of transceiver  42 . Slot  55  is created by a partial gap between lower shell  40  and an upper shell  40 ′. 
   Retractable spool  17  is shown in greater detail in  FIG. 7 . A spool body  60  is rotationally mounted to an axle  61  which is fixed within the fiber optic system (e.g., to the sleeve member of  FIG. 1  or to the housing shell of  FIGS. 3-6 ). A spring  62  (such as a leaf spring or a coil spring) is mounted between spool body  60  and axle  61  so that when fiber is fed out from the reel, energy is stored in the spring which can then be used to assist in re-coiling the fiber onto spool body  60  when being retracted. A brake  63  selectably engages mating features (not shown) in spool body  60  to maintain a desired position of the spool after a desired amount of optical fiber has been extended for use. Brake  63  can be disengaged in a known manner, such as by a manual lever (not shown) or a quick tug to disengage brake  63  from a catchment (not shown).