Multiplex communications – Communication over free space
Reexamination Certificate
1998-05-20
2001-10-02
Ton, Dang (Department: 2661)
Multiplex communications
Communication over free space
C370S388000
Reexamination Certificate
active
06298047
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a data communication system in which a data link is established between a portable data communication device and an interface circuit, such as an interface circuit that provides data communication access to a network or to another electronic device. In particular, the invention relates to an infrared data communication system in which a wireless data link is automatically established and retained between the portable data communication device and the interface circuit when an electrical signal transmitted from the communication device is detected within a defined communication area.
BACKGROUND OF THE INVENTION
In recent years, the use of portable data communication devices has become commonplace and even necessary in today's work environment. Workers must often travel from their offices and yet must retain connectivity to the workplace to access their workfiles and to respond to communications from others. Portable data communication devices, such as laptop computers, wireless telephones and pagers, facilitate travel outside of the workplace by enabling the mobile worker to maintain access to workfiles, such as via a modem or wireless link to a wired local area network (LAN), and to respond to communications from others, such as by e-mail, wireless telephone or pager.
Even within the work environment itself, workers often move about freely to attend meetings or to engage in conferences with co-workers. Yet, for a worker to retain connectivity to the workplace while moving about within the workplace, the worker must transport much of the same burdensome baggage as if he were traveling away from the workplace: a laptop computer, a pager, and perhaps even a wireless telephone, and possibly even a collection of wires and connectors. In addition, to gain access to the LAN, the internally mobile worker must find an available access port to establish a communications link, which may be difficult in conference rooms or offices where more than one user wants to connect. Thus, the worker may not be able to gain access to workfiles or presentation programs that would be useful when communicating to co-workers, or, if borrowing an access port assigned to another person, the mobile worker may not be able to access coded files or other privileges that have been tailored to the mobile worker's needs. Also, a worker who is often absent from his designated work space may often miss important communications from others, such as phone calls, because the worker cannot be located within the work facility.
Although solutions are known which address the foregoing problems, the solutions are not complete or introduce other complications. For example, to ensure that a mobile worker receives incoming communications, one known solution includes a public address system for paging the worker. Other more sophisticated solutions include systems that locate mobile workers within the work environment through the use of a network of wireless transmitters, such as badges worn by the worker, and receivers that may be mounted in fixed locations throughout the work facility. Once the individual's location has been determined, such systems may, for example, automatically route telephone calls to the telephone nearest the individual's location. Additionally, such systems may provide the individual with certain privileges, such as access to restricted work areas or customized automatic control of environmental conditions.
Solutions are also known that allow the internally mobile worker to freely access a local wired network regardless of the worker's location within the work facility. For example, many systems are known which permit the worker to establish a wireless data link between a portable communication device and a wired LAN. To ensure that the wireless data link remains intact regardless of the position of the portable communication device within the communication space, such systems typically use either RF or diffused IR. However, RF transmissions may be intercepted, thus compromising the confidential nature of many communications. Diffused IR suffers from being sensitive to interference from other optical sources, such as the fluorescent lamps commonly found in the work environment. Thus, it would be desirable to provide a data link that is relativity immune to optical or electronic interference and that is relatively difficult to intercept. An obvious solution is to provide an infrared (IR) line-of-sight data link between an IR transceiver in the communications device and an IR transceiver in communication with the LAN. However, such a solution may unduly restrict mobility within the work space because any inadvertent movement of the communication device or the IR transceiver in communication with the LAN may interrupt the data link. Further, the worker may not be able to freely alter the position of the communication device to permit others to easily view workfiles or other presentation materials displayed by the device. Moreover, the worker may be forced to sit in an inconvenient location solely for the purpose of establishing the data link.
Line-of-sight systems are known which address some of these shortcomings. For example, an infrared transceiver may be attached to a cable wired to the LAN such that the transceiver can be freely moved about the room or placed in various positions on a work surface, such as on a conference table or a desk top. Or, once a link is established between the communication device and the transceiver, an alarm may sound if the individual starts moving the communication device out of range of the transceiver. Still another solution is to lock the position of the communication device relative to the transceiver through the use, for example, of magnets or other types of restraining devices. However, all of these solutions are awkward in certain respects.
Thus, it would be desirable to provide a more elegant solution to these problems than offered by known systems. Such a solution would allow a worker to move freely about the work facility without hindering access to wired systems, such as a LAN. Such a solution also would be capable of locating the worker within the work facility such that communications can be automatically routed to the worker and such that the worker may enjoy certain customized privileges regardless of the worker's location. Locating the worker could be accomplished, for example, by detecting the presence of the worker's portable communication device within a known work area. Further, such a solution would provide a secure data link between the communication device and the LAN that is relatively immune to interference from other optical or electronic sources. Moreover, the solution would ensure that the data link remains intact, despite movement of the portable communication device, without the use of annoying alarms, lengthy cables that clutter the work area, or cumbersome locking devices. The solution could also be used in applications other than data communications with a LAN. For example, a data link could also be established and retained between the portable communication device and an interface circuit that provides data communication access to other electronic devices, such as printers, other peripherals, televisions, etc.
SUMMARY OF THE INVENTION
The present invention provides for detecting the presence of a portable communication device within a work space and then establishing and retaining a data link between the portable communication device and an interface circuit, such as a network access circuit or a serial or parallel communication port. Thus, in accordance with a first aspect of the invention, a wireless data communication system includes an interface circuit, a plurality of transceivers configured to transmit and receive wireless signals within a transceiver space associated with each transceiver, and a control circuit in communication with the interface circuit and the plurality of transceivers. The control circuit initiates a scanning se
Steffes Christopher Carl
Tonizzo Anthony
Vallillee, IV George William
Foley & Lardner
Sam Phirin
Steelcase Development Inc.
Ton Dang
LandOfFree
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