Personal paging, communications, and locating system

Claims

I claim:

1. A method for transmitting a message to an individual, comprising the steps of:

originating said message addressed to said individual;

transmitting the message to a central communications station;

receiving and storing the message at said central communications station;

creating a packet containing data from the message;

transmitting said packet to a communications unit carried by the individual by the steps of:

(1) computing an error checking code and adding said code to the packet;

(2) adding a code to the packet identifying said communications unit;

(3) transmitting the packet by means of radio to the communications unit;

(4) receiving the packet at the communications unit;

(5) computing an error checking code;

(6) determining whether the packet has been correctly received by comparing the error checking code computed at the communications unit with the error checking code contained in the packet;

(7) constructing a packet at the communications unit comprising a code identifying the communications unit;

(8) adding a code identifying and thus acknowledging the received packet to said packet constructed at the communications unit, should the received packet contain a correct error checking code;

(9) transmitting the packet constructed at the communications unit from the communications unit via a medium selected from the group consisting of infrared light and ultrasonic sound to one or more of a plurality of remote stations, should the received packet contain a correct error checking code;

(10) receiving the packet constructed at the communications unit from the communications unit at a remote station and temporarily storing it;

(11) transmitting the packet constructed at the communications unit from said remote station, by means of a communications circuit via a medium selected from the group consisting of wire and optical fiber, to said central station;

repeating the steps of creating the packet containing data from the message and transmitting the packet to a communications unit carried by the individual, until all data in the message has been transmitted from the central station to the communications unit;

displaying said message to the individual.

2. The method of claim 1, wherein the step of transmitting the packet from the communications unit comprises the steps of:

transmitting a poll packet from the central station containing a code identifying the communications unit;

receiving said poll packet at the communications unit;

transmitting the packet from the communications unit.

3. The method of claim 1, wherein the step of transmitting the packet to the communications unit comprises the steps of:

determining a priority for each incoming message, with at least one level reserved for incoming telephone calls;

assigning said priority to each packet the message is broken up into, with each packet containing a code indicating the priority;

allocating capacity of the radio communications channel such that messages with higher priority are given preference;

providing a humanly perceptible signal to the user at the communications unit when messages of particularly high priority have been received.

4. The method of claim 1, further comprising the steps of:

transmitting a packet from the central station to each communications unit containing a sequence number for the last packet transmitted containing message text;

receiving said packet containing said sequence number at the communications unit;

determining whether packets containing message text have been transmitted to the communications unit but not received by the unit;

providing a humanly perceptible signal to the user when it has been determined that a packet containing message text has not been received.

5. The method of claim 1, wherein the step of transmitting the packet from the remote communications station comprises the steps of:

transmitting a poll packet from the central station to the remote station;

receiving said poll packet at the remote station;

transmitting a packet from the remote station to the central station in response to said poll packet that contains those packets received from communication units since the receipt of the last poll packet at the remote station.

6. The method of claim 1, wherein a plurality of packets is transmitted from the central station to the communications unit before an acknowledgement is received for any of the packets.

7. The method of claim 6, wherein transmission of a packet from the central station comprises the steps of:

assigning a sequence number to the packet;

transmitting the packet to the communications unit with said sequence number included as part of the packet;

receiving the packet and checking the packet for errors at the communications unit;

transmitting a response from the communications unit containing an acknowledgement of the original packet, with the acknowledgement containing the sequence number of the original packet.

8. The method of claim 7, wherein transmission of the packet comprises the steps of:

transmitting a packet containing a sequence number to the communications unit;

waiting for a predetermined length of time for a response from the communications unit containing an acknowledgement with the corresponding sequence number;

removing the packet from a queue of packets to be transmitted should an acknowledgement be received;

ignoring any further acknowledgements that are received for packets already removed from said queue of packets to be transmitted;

retransmitting the packet to the communications unit, should an acknowledgement with the proper sequence number not be received within the predetermined length of time.

9. The method of claim 8, wherein retransmission of an unacknowledged packet comprises the steps of:

determining the identity of the remote station last receiving a packet from the communications unit;

determining the time of receipt of said packet from the communications unit;

computing the probability that the unit is likely to receive the retransmitted packet if it is transmitted at the time the probability is computed at;

retransmitting the packet if the probability of receipt is above a certain threshold value.

10. The method of claim 1, wherein the step of transmitting the packet from the communications unit comprises the steps of:

transmitting the packet from the communications unit;

waiting for a specified period of time until the next transmission of the packet; in which the above steps are carried out repeatedly.

11. The method of claim 10, wherein the time delay before the next transmission of the packet is determined by the steps of:

determining the time since the last receipt of a packet with message text;

computing a time delay such that the frequency of repeated transmissions decreases as the time since the last receipt of a packet with message text increases.

12. The method of claim 10, wherein the step of transmitting the packet from the communications unit comprises the steps of:

transmitting the packet from the communications unit;

transmitting a packet from the central station to the communications unit acknowledging the acknowledgement of the original packet;

receiving said packet acknowledging the acknowledgement at the communications unit;

removing the sequence number of the acknowledged packet from the list of packets for which acknowledgements will be sent.

13. The method of claim 10, wherein the repeated transmission of the packet from the communications unit continues with the packet containing the unit identification code alone, should all received packets have been acknowledged.

14. A method for transmitting a message to an individual and returning a response to the originator of said message, comprising the steps of:

originating the message addressed to said individual;

transmitting the message to a central communications station;

receiving and storing the message at said central communications station;

creating a packet containing data from the message;

transmitting said packet to a communications unit carried by the individual by the steps of:

(1) computing an error checking code and adding said code to the packet;

(2) adding a code to the packet identifying said communications unit;

(3) transmitting the packet by means of radio to the communications unit;

(4) receiving the packet at the communications unit;

(5) computing an error checking code;

(6) determining whether the packet has been correctly received by comparing the error checking code computed at the communications unit with the error checking code contained in the packet;

(7) constructing a packet at the communications unit comprising a code identifying the communications unit;

(8) adding a code identifying and thus acknowledging the received packet to said packet constructed at the communications unit, should the received packet contain a correct error checking code;

(9) transmitting the packet constructed at the communications unit from the communications unit via a medium selected from the group consisting of infrared light and ultrasonic sound to one or more of a plurality of remote stations, should the received packet contain a correct error checking code;

(10) receiving the packet from the communications unit at a remote station and temporarily storing it;

(11) transmitting the packet originating from the communications unit from said remote station, by means of a communications circuit via a medium selected from the group consisting of wire and optical fiber, to said central station;

repeating the steps of creating the packet containing data from the message and transmitting the packet to a communications unit carried by the individual, until all data in the message has been transmitted from the central station to the communications unit;

displaying said message to the individual;

accepting a response message by the individual at the communications unit in response to the received message;

transmitting said response message from the communications unit by means of a medium selected from the group consisting of infrared light and ultrasonic sound to one or more of a plurality of remote stations;

receiving the response message at a remote station and temporarily storing the response message;

transmitting the response message from said remote station by means of a communications circuit via a medium selected from the group consisting of wire and optical fiber to the central station;

receiving the response message at the central station;

transmitting the response message from the central station to the originator of the message;

receiving the response message by the originator of the message.

15. The method of claim 14, wherein the step of transmitting the response message comprises the steps of:

transmitting the response message from the communications unit;

waiting for a specified period of time until the next transmission; in which the above steps are carried out repeatedly.

16. The method of claim 14, wherein the step of transmitting a response message comprises the steps of:

selecting said response message from a set of preprogrammed responses;

encoding the response message as a numerical index to said set of preprogrammed responses rather than the text itself.

17. The method of claim 14, wherein transmitting the message and accepting a corresponding response message comprises the steps of:

assigning a channel number to each message received at the central station;

transmitting the message from the central station to the communications unit, with said channel number contained in the message;

transmitting the response from the communications unit to the central station, with the channel number contained in the response;

converting the channel number to an electronic mail address identifying the originator of the message;

transmitting the response to the originator of the message by use of said electronic mail address.

18. The method of claim 14, further comprising the steps of:

displaying a preprogrammed response to the user at the communications unit;

editing the text of the response by the user at the communications unit;

transmitting the modified response to the central station to update the corresponding list of preprogrammed responses stored at the central station.

19. The method of claim 14, wherein the step of transmitting the response message comprises the steps of:

transmitting the response message from the communications unit, with the response message containing a sequence number identifying the particular response message;

receiving the response message with corresponding sequence number at the remote station and forwarding it to the central station;

receiving the response message with corresponding sequence number at the central station;

transmitting a packet from the central station to the communications unit acknowledging the response message that contains the corresponding sequence number;

ignoring further copies of the response message, as indicated by the sequence number, that may be received at the central station.

20. The method of claim 19, wherein the step of transmitting the response message comprises the steps of:

transmitting the response message from the communications unit;

waiting a specified period of time after transmission;

providing a humanly perceptible signal to the user of the communications unit, should an acknowledgement of the response message fail to be received within said specified period of time.

21. The method of claim 14, further comprising the steps of:

initiating a message requesting that a physical location be provided for the communications unit assigned to an individual;

transmitting said message to the central station;

determining the last known location of the communications unit assigned to said individual;

transmitting a reply message to the initiator of the request containing the location of the communications unit.

22. The method of claim 21, wherein the step of transmitting the reply message to the initiator of the location request comprises the steps of:

determining whether the communications unit for which the request has been received has had a privacy mode selected by the user;

transmitting a message to the initiator of the location request indicating that said privacy mode has been selected, rather than indicating the location of the communications unit, should the privacy mode be selected.

23. The method of claim 14, further comprising the steps of:

transmitting part of the message stored at the central station to the communications unit;

displaying the part of the message received at the communications unit to the user, together with a response that, when chosen, requests additional text from the message;

choosing said response requesting additional text by the user;

transmitting a code representing the response together with identification of the message from the communications unit to a remote station and then to the central station;

transmitting additional text from the message from the central station to the communications unit;

displaying additional message text to the user.

24. The method of claim 23, further comprising the steps of:

the user performing an action at the communications unit communicating his or her intention of deleting a message;

deleting the part of said message received by the communications unit from its memory;

transmitting a code indicating a deletion request, together with identification of the message to be deleted, from the communications unit to the remote station and then to the central station;

deleting the message stored at the central station.

25. The method of claim 24, wherein the deletion of the message comprises the steps of:

deleting the part of the message received by the communications unit from its memory while saving the message in a temporary memory;

deleting the message stored at the central station, while saving the message in a temporary memory;

selecting a command by the user communicating the intention of reversing the delete action;

restoring the portion of the message received by the communications unit that had been deleted by obtaining the text from said temporary memory in the communications unit;

transmitting a code representing said reversing of the delete action to the remote station and then to the central station;

restoring the message in the central station that had been deleted to its original state by obtaining the message text from said temporary memory in the central station. the message text from said temporary memory in the central station.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application relates to a copending application submitted by Craig A. Will entitled "Control of Miniature Personal Digital Assistant Using Menu and Thumbwheel," Ser. No. 08/423,690, filed Apr. 18, 1995. The application also relates to a copending application submitted by Craig A. Will entitled "Wireless Personal Paging, Communications, and Locating System", Ser. No. 08/200,065, filed Feb. 22, 1994, now U.S. Pat. No. 5,479,408, issued Dec. 26, 1995.

FIELD OF THE INVENTION

This invention relates generally to electronic communication systems for sending signals selectively to portable receivers that provide an indication or alarm to specific individuals that is humanly perceptible, and further to systems that indicate the location of individuals. It relates to the transmission of message data encoded as digital pulses modulating a radio wave to portable receivers, and also relates to the transmission of message data, identification, and location information using digital pulses optically, particularly by infrared light, and acoustically, particularly by ultrasound. The invention further relates to the indication of incoming calls from a telephone PBX system and the forwarding and transfer of such calls.

More specifically, the invention relates to a system for communicating with individuals in a building using digitally encoded radio in one direction and either infrared light or ultrasound in the other, with users receiving paging indications and messages and being able to acknowledge and respond to messages and to originate messages, with the system also tracking the location of and providing communications to allow users to transfer incoming telephone calls remotely.

BACKGROUND OF THE INVENTION

A frequent difficulty in an office or similar environment is communicating with a particular individual when they are not in their office but still in the building. This results not only in "telephone tag" where people continue back-and-forth attempts to return telephone calls, but also in its physical analog where one person visits the office of another, only to find that person to be gone.

One solution to this problem has been the increasingly widespread use of paging receivers, and such devices have become more and more miniaturized. Devices have been constructed, for example, that are the size of a credit card or that are included as part of a watch. Such systems, however, are typically one-way, transmitting only a telephone number, perhaps an additional short numeric code, or possibly a brief alphanumeric message, and are designed for use outside a building.

Within a building, there have been two general directions that system designs have taken. One is the use of radio paging systems within a building, which may be configured to allow receipt of electronic mail messages or to allow users to be notified that they have a call that they can then ask to be transferred to a nearby extension. For example, the Hagl invention (U.S. Pat. No. 5,151,930) transmits the fact of the incoming call and the telephone extension of the calling party by radio to a paging receiver, which indicates to the user that the call has come in and displays the number. The user then locates a telephone instrument and dials a code identifying the user, resulting in the incoming call being transferred to that instrument.

The other direction is the use of automatic personal locating systems that determine where in a building an individual is, and that can automatically route a telephone call to the nearest extension. For example, the Ward invention (U.S. Pat. No. 3,439,320) describes a system that uses ultrasonic sound (using a different frequency for each person) to track the location of individuals in a building so that telephone calls may be routed to them. A number of variations exist using different media. Thus, the Shipley inventions (U.S. Pat. Nos. 4,601,064 and 5,062,151) track the location of individuals that carry devices that repeatedly transmit a digital identifying code via infrared light that is then received by remote sensors installed in individual rooms of a building, with a central computer that polls the remote sensors and determines the location of an individual. Telephone calls can then, if desired, be automatically forwarded to the individual by the PABX system. The individual can, using a switch on the identification device, turn off the forwarding action at a given time if it would be inconvenient.

These approaches have a number of drawbacks. One-way radio paging signals can fail to deliver a messages if the user is in an especially noisy environment, is in a "dead spot" resulting from metal shielding or other interference, or goes outside the range of the transmitter. While these difficulties can be prevented by repeating all transmissions multiple times, this approach does not make efficient use of bandwidth and can also result in considerable delay in receipt of a paging signal or message. One-way communication also does not allow an originator to know whether a message has in fact been received by a user and read, or allow the user to respond. One-way systems that indicate to a user only that a call has come in require the user to find a telephone and dial sufficient digits to cause the call to be transferred, and typically require the caller to be placed on hold during this process, which may be annoying to the caller if the person being paged does not respond or takes a long time to do so.

Systems that automatically track the location of individuals and automatically transfer incoming telephone calls to that location tend to be intrusive, because they necessarily cause a transfer even in circumstances that might be inappropriate (such as transferring a call to an individual who is in an office of someone he or she does not know well or who is in a group meeting that might be disturbed).

The above difficulties are solved by the invention disclosed here (and related inventions) by its provision of both (1) two-way communication and (2) automatic tracking of the location of the individual. This combination allows responses to be sent which are chosen from a set provided with the original message, from a preprogrammed set, or composed by the user. Selection or composition of responses is made easy by use of a thumbwheel that allows display of messages and responses and their choice by pressing a single key (as is described in a copending application). The communication and tracking system also makes possible the transfer of incoming telephone calls remotely by means of selection from a menu.

The present invention provides both two-way communication and tracking by making use of a hybrid communication system with radio used for transmitting data to the user, and infrared light (or, in an alternative embodiment, ultrasonic sound) used for receiving data from the user. This hybrid system makes effective use of the strengths of each form of communication. Radio is used in one direction for broad coverage, ease of implementation, and relative reliability, while infrared light (or ultrasound) is used in the other direction (for acknowledgements, responses, original messages, and location tracking) because of its low power requirements, simplicity of design, small size of the necessary electronics, low cost, and its ability to determine the location of individuals (since infrared light and ultrasonic sound do not pass through walls). Radio is also desirable because its use could allow the design of a paging receiver that works both with conventional paging systems when outside the building and, in addition, with the system described here when inside the building, using the same components.

The use of this hybrid mix of communication media required the design of a communication protocol to fit the characteristics of the two media. The radio medium is characterized by good but not perfect reliability, and moderate to substantial capacity, depending upon availability of particular bands and whether the station is licensed or unlicensed. The system is particularly applicable for use in the recently allocated 1,900 Mhz band for personal communications services for unlicensed use in a building. The infrared medium has somewhat limited capacity in this context because of the need for data to be transmitted repeatedly and because of the need to minimize drain on the battery and to minimize conflict with other nearby communication units. Ultrasound has a naturally low capacity resulting from its susceptibility to interference from echoes as the signal bounces off walls, floor, and ceiling. Both infrared, and, to a lesser extent, ultrasound, have somewhat variable reliability as the user moves from one room to another and as the unit changes position and orientation in that environment. Infrared and ultrasound, are, of course, desirable because they do not easily penetrate walls and ceilings and thus allow reliable identification of the location of the unit.

One example of the requirements for the protocol is illustrated by the fact that unlike more conventional protocols where data is transmitted and an acknowledgement signal is expected immediately if the data has been correctly received, with this protocol data must be sent without waiting for immediate acknowledgement of previous packets, with data broken down into packets with assigned sequence numbers and both data and acknowledgement packets containing the appropriate numbers. This is necessary because with a hybrid system, one direction can be reliable at a time when the other is not, and vice-versa. Other characteristics of the protocol include modifying the rate of repeated transmissions from units and polling to and transmissions from remote stations depending on the probability of expected responses and the user of indicators to signal to the user the status of the communication links, particularly when communication is being impeded.

SUMMARY OF THE INVENTION

The goal of the method and apparatus disclosed here is to provide a communications system that can send paging signals and brief messages to individuals within a building or complex of buildings, accept and deliver responses to these messages, and identify the location of individuals within the building.

Individuals communicate with a central communications station by means of a miniature communications unit carried by the individual that is typically about the size of a credit card and can be integrated into a wearable plastic corporate identification badge. The communications unit displays messages visually and can provide a visual and/or auditory alarm indicating the receipt of a message. Users can view messages and select or compose responses by means of a thumbwheel rotating cylinder and key. The unit consists of a microprocessor, a memory, a radio antenna and receiver, a speaker, a visual display, an infrared diode emitter, a thumbwheel and key, and visual and auditory indicators.

Communication from the central communications station to each individual unit is carried out by frequency-shift-keyed digital radio, with a single radio transmitter and antenna typically used for a single building or building complex. Communication from each unit to the central communications station is carried out by a combination of infrared light and wire or optical fiber. Remote communication stations that include an infrared light sensor are installed in individual rooms of the building and along corridors, and data is sent from the unit first to a remote station by infrared and then forwarded to the central station by wire or optical fiber.

The communications system is integrated into the telephone and electronic mail systems typically found in an office environment. A message may be generated as a result of a telephone ringing signal, the leaving of a voicemail message, or the receipt of an electronic mail message (either messages specifically intended to be sent to the remote unit or messages directed to the user's normal electronic mail address, the latter particularly if the sender or topic of the message matches a description provided by the user).

The system allows others (if desired by a user) to determine the current physical location of the user by sending an appropriate "location query"