Abstract:
A communications system ( 30 ) enables two communications devices ( 10, 12 ) to communicate with each other over an extended distance using a limited range communication protocol, such as the IrDA or Bluetooth protocol. The communications system includes a pair of repeaters ( 32, 34 ), each having a protocol stack ( 38 ) that includes a portion of the limited range communications protocol. The repeaters communicate with each other over an extended range communications channel ( 36 ) such as the PSTN, while each communications device utilizes its native, limited range communications technique to communicate with an associated repeater. Thus, each communications device can readily communicate with another like device using its native protocol over a distance otherwise beyond the range of that technique.

Description:
CROSS-REFERENCE TO CONTINUING APPLICATION 
   This application constitutes a continuation-in-part of co-pending U.S. patent application Ser. No. 10/134,163, filed Apr. 26, 2002, now abandoned, which claims priority under 35 U.S.C. 119(e) to U.S. Provisional Patent Application 60/347,386, filed Jan. 10, 2002. 

   TECHNICAL FIELD 
   This invention relates to a technique for data communication between wireless devices over a distance. 
   BACKGROUND ART 
   Presently, different types of data communications devices, such as lap top computers, and Personal Data Assistant devices (PDAs), incorporate an infrared data communications port for transmitting data to, and receiving data from a device that has a similar type infrared data communications port. Some computer peripheral devices, such as printers, also have an infrared data communications port for receiving infrared signals from a lap top computer or PDA to allow wireless receipt of data by such a peripheral device. While different protocols exist to facilitate communication of data via infrared signals, the IrDA protocol established by the Infrared Data Association, an industry-based standards body, has achieved widespread acceptance as the infrared data communications protocol of choice for many manufacturers of data communications devices and peripherals. 
   Providing a data communication device such as a laptop computer or PDA with an infrared data communication port allows a user to accomplish data exchange with a data communication device or peripheral device that likewise has an infrared data communications port without the need for any cable linking the devices. Indeed, the user need only position his/her data communication device generally within the line of sight of the recipient device to send data thereto and to receive data therefrom via infrared beams. 
   Another wireless communications protocol is the Bluetooth protocol. The Bluetooth communications protocol allows devices so equipped with this protocol to exchange information over Radio Frequency channel, as compared to the IrDA protocol, which utilizes an infrared beam. In contrast to the IrDA protocol, the Bluetooth protocol doesn&#39;t suffer from a line of sight restriction. 
   Current day wireless communications protocols, such as the above-described IrDA and Bluetooth protocols typically make use of relatively low power transceivers within the device, affording a relatively short communication range. For, example present day devices utilizing the IrDA protocol often have a communication of about 3 meters, while Bluetooth-equipped devices often have a communication range of 100 meters. Safety constraints, radio frequency interference issues, and power consumption constraints all play a role in limiting the range these communications protocols. 
   Many users of communications devices that embody such present-day limited range communication protocols often desire to exchange information with other device users but cannot do so using such communication protocols because the distance between devices exceeds the maximum allowable range. While other communications techniques do exist which have a longer range, such techniques have a different user interface, making ease of use more difficult. 
   Thus, a need exists for a communication technique capable of extending the range of a limited range communications protocol such as the IrDA and Bluetooth Protocols. 
   BRIEF SUMMARY OF THE INVENTION 
   Brief, in accordance with the present principles, there is provided a method for communicating information over an extended distance between first and second communications devices, each employing a limited range communications protocols. Such limited range protocols can include the IrDA and Bluetooth protocols. The method commences upon the receipt at a first repeater station of a communications packet, sent from the first communications device via the limited range communications protocol. The first repeater station has a protocol stack containing at least a portion of the limited range communications protocol to enable receipt of the communications packet from the first device transmitted using the limited range communications protocol. The first repeater then forwards the communications packet across an extended range communications channel (e.g., a phone line or broadband link) via a protocol different than the limited range communications protocol to a second repeater station having protocol stack that also contains at least a portion of the limited range communications protocol. The second repeater transmits the communications packet to the second user via the limited range communications protocol. In this way, the first and second communications devices can exchange information using their native communications protocol over an extended distance. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  discloses a block schematic diagram of a pair of portable data communications devices communicating via a limited range communications protocol in accordance with the prior art; and 
       FIG. 2  discloses a block schematic diagram of a communications system in accordance with the present principles for enabling the portable communications devices of  FIG. 1  to communicate with each other over an extended distance using their native, limited range communications protocols. 
   

   DETAILED DESCRIPTION 
   The communications technique of the present principles enables two communications devices, each using a limited range communications protocol, to communicate over an extended distance. To best understood the technique of the present principles, a understanding of how such devices communicate using the limited range communications will prove helpful.  FIG. 1  depicts a block schematic of first and second of portable data communications  10  and  12  devices communicating via a limited range communications protocol in accordance with the prior art. In embodiment of  FIG. 1 , the portable communications devices  12  and  14  take the form of a Personal Data Assistant (PDA) that communicate with each other an infra red beam using the IrDA communications protocol. Alternatively, the PDAs  10  and  12  could user another other limited range communication protocol such as the Bluetooth protocol. Presently both the Bluetooth and IrDA protocols enjoy application in a wide variety of communications devices other than PDAs  10  and  12 . 
   Both of the PDAs  10  and  12  of  FIG. 1  have the same structure, so like numbers designate the same element in each device. Each PDA includes a processor  15  that executes an operating program that implements a communications protocol having individual protocols stored in a stack  16 . In the illustrated embodiment, the stack  16  stores a set of individual protocols  20   1 - 204 , which collectively implement the IrDA protocol, thus allowing the PDA to send and receive communications packets to another PDA via an infrared transceiver  18 . 
   To better understand the IrDA protocol, consider each of the individual protocols  20   1 - 20   4  stored in the stack  16 . During a simple transmission of information from the PDA  10  to the PDA  12 , the processor  14  in the PDA  10  operating under control of the an operating system first activates a high-level protocol  20   1 , typically the IrOBEX protocol, to initiate the transfer of desired information. The IrOBEX protocol  20   1  activates a transport protocol  20   2 , such as the TinyTP protocol, at a level below the IrOBEX protocol, to provide reliable transport. Activating the TinyTP protocol  20   2  activates a link layer protocol  20   3 , such as the IrLMP protocol, residing below the Tiny Tp protocol, to create a communications link to the other PDA for transport. 
   The IrLMP protocol  20   3  activates a physical layer protocol  20   4  below the IrLMP protocol to locate the other PDA for linkage. The physical layer protocol typically includes the IrLAP protocol which makes use of the IrPHY protocol to handle the packetization of the data converted by the IR  18  transceiver into bursts of infrared light conforming to the IrDA physical interface specification. 
   Upon receipt of the communications packet at the PDA  12 , the above-described protocols  20   1 - 20   4  in the stack  16  of that PDA operate in reverse. In other words, the IrLAP/IrPHY protocol  20   4  at the bottom of the stack operates to receive packets, whereas the IrLMP protocol  20   3  operates to answer a request for a connection. The TinyTP protocol  20   2  provides reliable transport so that the actual data record desired can be conveyed using the IrOBEX protocol  26   1 , at the top of the stack of the receiving PDA  12 . In the illustrated embodiment, each PDA can also include one or more additional protocols, such as the IrComm protocol  20   5  which are not active during an IrOBEX exchange as described above. 
   The above described method only works when the PDAs  10  and  12  lie within the visible IR range of each other (about 3 meters). A similar limitation (about 100 meters) exists where the PDAs utilize the Bluetooth radio protocol rather than the IrDA protocol. 
     FIG. 2  depicts a communications system  30  in accordance with a preferred embodiment of the present principles for enabling two communications devices, such as the PDAs  10  and  12 , to communicate over an extended distance using a limited range communications protocol, such as IrDA or Bluetooth protocols. In other words, the communications system  30  of  FIG. 2  allows the PDAs  10  and  12  to communicate using a low range communications protocol, in the manner described above, but over a distance that heretofore exceeded the range of such a protocol. In this regard, not only the IrOBEX protocol  20   1  can be conveyed using the method of present principles, but also the IrComm protocol  20   5 , as well as any other protocol used above the IrLAP protocol layer. 
   The communications system  30  comprises a pair of repeaters,  32  and  34  linked by a communications network  36 , illustratively represented by the Public Switched Telephone Network (PSTN). The network  36  could take on other forms such as a Local Area Network, a Wide Area Network, a wireless network, (e.g., cellular or Wi-Fi), a corporate Intranet, or the Internet, or some combination of networks. Each of the repeaters  32  and  34  has the same structure and therefore only the details of repeater  32  appear here. The repeater  32  includes an IR transceiver  36  that has the same structure and operates in the same manner as the transceiver  18  in each of the PDAs  10  and  12 . Thus, the transceiver  36  of  FIG. 2  sends and receives communications packets in accordance with the IrDA protocol. The transceiver  36  connects to a processor  37 , which executes an operating system that relies on a communications protocol comprised of a plurality of individual protocols stored in a stack  38 . 
   The communications protocol implanted by the processor  37  within each of the repeaters  32  and  34  will implement the limited range communications protocol of the PDAs  10  and  12 . Thus, the protocol stack  38  within each repeater  32  will contain some but not all of the same protocols as the protocol stack  16  in each of the PDAs  10  and  12 . In the illustrated embodiment, the protocol stack  38  contains a slightly modified version of IrLAP/Ir/PHY protocol  20   4  that is contained in the protocol stack  16  in each PDA. The presence of the IrLAP/Ir/PHY protocol  20   4  facilitates the transfer of communications packets formatted in the IrDA protocol between the processor  37  and the transceiver  36 , thus allowing each repeater to exchange such communications packets with an associated PDA. 
   Unlike the protocol stack  16  within each of the PDAs  10  and  12  that includes the IrOBEX, TinyTP, and IrLMP protocols  20   1 ,  20   2  and  20   3 , respectively, the protocol stack  38  contains a protocol IrConduit  40  which recognizes a communications attempt from a PDA or a similar device using the IrDA protocol. In response, the IrConduit protocol will establish a data connection via a modem  42  to the repeater  34  through communications network  36  to enable communications with the PDA  12  associated with repeater  34 . 
   The structure of the modem  42  in each of the repeaters  32  and  34  will depend in large measure on the nature of the communications network  36  that carries packets between repeaters. In the illustrated embodiment where the communications network comprises the PSTN  36 , the modem  42  in each of the repeaters  32  and  34  typically comprises a telephony-type data modem having a data rate of 33.6 K baud although a higher data rate will assure faster data communications. As discussed, the network  36  can take other forms, and to that end, the modem  42  in each repeater will have a structure compatible the network. 
   To best understand the manner in which the communications system  30  of the present invention enables communication between the PDAs  10  and  12  across a distance greater than the limited range of the IrDA protocol, consider the exchange of a contact record between the two PDAs as described above with respect to  FIG. 1 . To exchange a record with the PDA  12 , the PDA  10  attempts an communications exchange with the repeater  32 . The repeater  32  recognizes the attempt to communicate (using its implementation of the IrLAP protocol  20   4 ). The IrConduit protocol  40  establishes a data connection through the modem  42  to the modem  42  in the repeater  34  across the PSTN  36 . After establishing a connection, the IrDA commands embodied in the IrPHY and IrLAP protocol  20   4  of the repeater  32  enable the PDA  10  to search for, and establish a connection with the PDA  12  via the repeater  34 , thus enabling the exchange of data, just as if the two PDAs lay within the limited distance required for the IrDA protocol. Once the PDAs  10  and  12  have completed the transfer, the repeaters  32  and  34 , respectively, can disconnect, either in response to a command from one of the PDAs, or in response to a time out. 
   By interpreting and manipulating the IrDA data packets as they are received, the repeaters  32  and  34  permit a connection between the PDAs  10  and  12  to progress normally, such that the PDAs appear to each other as being directly connected. The method of the preset principles also has applicability for transporting Bluetooth data packets that use the same low level protocols as IrDA. Depending on the speed of the media (e.g. 33.6 k baud modem, or 10 mbit/sec LAN) the communication speed between the PDAs across the network  36  may be slower that what would be possible with the devices in direct range of each other (115 k baud). There may also be a delay in starting up a communication with a remote device as compared with one in direct range, due to time needed to establish the long distance connection between the conduit devices. 
   The foregoing describes a technique for enabling two communications device to communicate over an extended distance using a limited range communications protocol.