High capacity protocol with multistation capability

• US 4,897,835 A
• Filed: 05/12/1989
• Issued: 01/30/1990
• Est. Priority Date: 11/27/1985
• Status: Expired due to Term

• Current Assignee: Protocol-ip.com, LLC, Seiko Instruments Incorporated (Seiko Group)
• Original Assignee: AT&T, Inc.
• Inventors: Dey, Norbert E., Park, Daniel J., Gaskill, Garold B., Ragan, Lawrence H., Peek, William H.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Marcelo, Melvin
• Application Number:
  US07/352,635
• Time in Patent Office: 263 Days
• Field of Search: 370/17, 370/94, 370/95, 370/99, 455/32, 455/38, 455/70, 455/71, 340/825.44, 379/97, 371/37
• US Class Current: 370/314
• CPC Class Codes: G04G 21/04 using radio waves radio-controlled time-pieces G04R
• CPC Class Codes: G04R 20/14 the radio signal being a telecommunication standard signal, e.g. GSM
• CPC Class Codes: G04R 20/20 the radio signal being an AM/FM standard signal, e.g. RDS
• CPC Class Codes: G04R 60/04 Antennas attached to or integrated in watch bracelets
• CPC Class Codes: G08B 3/1016 using wireless transmission calling systems using transmission by inductive loop H04B5/00
• CPC Class Codes: G08B 5/223 using wireless transmission
• CPC Class Codes: G08B 5/228 combined with other devices having a different main function, e.g. watches
• CPC Class Codes: H04L 1/18 Automatic repetition systems, e.g. Van Duuren systems
• CPC Class Codes: H04W 88/026 using digital address codes
• CPC Class Codes: H04W 88/187 using digital or pulse address codes
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A wide area paging system is disclosed in which paging messages input to the system in one local area can be broadcast to a receiver in any other local area without necessarily broadcasting the message in all areas. A local area clearinghouse in each area stores resident subscriber data including current location and receiver serial number. This data is used to transfer messages over a data network to the correct clearinghouse. The system uses a TDM data protocol. The data is encoded and transmitted at a very high rate (e.g., 19,000 baud) in short packets (256 bits/13 milliseconds) via stereo FM sidebands. Receivers are assigned to receive sequentially numbered time slots matching a portion of their address. The addresses of intended receivers are included in the data packets. Battery-powered receivers are deactivated between packets and reactivated in accordance with the sequential time slot number scheme to receive an incoming packet. Messages longer than a packet are segmented and transmitted in two or more packets, linked together by data contained in the packets. A watch pager used in the system employs a wristband antenna which electromagnetically couples to the user'"'"'s body. The watch pager displays time, telephone numbers and icons representing common types of paging messages.

Claims

1. In a time division multiplexed communication method of transmitting periodic frames of a first duration subdivided into subframes having time slots of a second duration, the subframes and time slots having unique identification numbers, and assigning receivers an address that includes a unique number as one portion of the address and a subframe and time slot identification number as another portion, and encoding data into digital data packets bearing a time slot identification number, each packet of substantially equal duration to a time slot, a method of transmitting multiple messages for one or more receivers in a single time slot, comprising:

encoding format information within the data packet which alerts receivers assigned the time slot number as a portion of their address that more than one message is contained in the packet;

placing the messages in predetermined positions within the packet to be recognized by the alerted receivers as multiple messages; and

encoding within each message an address that corresponds to the unique numbered portion of the receiver address so that only the intended receiver reads the message.

2. The method of claim 1 in which the message itself contains format information indicating to the addressed receiver that the information therein is either an actual data message or is a pointer to a target time slot where the data message can be found.

3. The method of claim 2 in which the actual data messages are transmitted as binary numbers corresponding to predetermined messages.

4. In a time division multiplexed communication system having a transmitter system comprising a plurality of stations transmiting on different frequencies digital data packets to a plurality of receivers each having an address, a method of increasing the number of individual receivers that can be served by a single transmitter system, comprising:

encoding format information in a data packet uniquely addressed to a receiver within the transmitter system indicating that the data therein is received control information rather than message information;

encoding in the receiver control information the identification of stations within the transmitter system to which the addressed receiver must tune for message information;

transmitting the data packet from all stations within the transmitter system to alert the addressed receiver to tune to any of the identified stations; and

transmitting the data packets having message information to the addressed receiver only from the identified stations.

5. The method of claim 4 in which encoding the identification of stations comprises identifying each station by a time offset that corresponds to the station'"'"'s frequency in a list of frequencies and offsets known to the receiver.

6. In a time division multiplexed communication system having a plurality of transmitter systems each comprising a plurality of stations for transmitting on different frequencies digital data packets including system control packets to a plurality of receivers each having an address, a method of splitting the receivers in an area among several transmitter systems to increase the number of receivers that can be served, comprising:

encoding in a control packet a mask bit field corresponding to a predetermined portion of a receiver'"'"'s address;

encoding in a control packet an address field corresponding to the same portion of the receiver address; and

masking bits in the mask bit field to indicate the bits in the address field that must be matched by the corresponding portion of the receiver address for the receiver to be served by the transmitter system transmitting to the control packet.

7. In a time division multiplexed communication system having a transmitter system comprising a plurality of stations for transmitting on different frequencies data packets including system control packets and message packets to a plurality of receivers each having an address, a method of improving the probability of reception of the message packet by the receiver, comprising:

offsetting the time of transmission of data packets from each station within the transmitter system so that the same data packets are transmitted at different relative times;

encoding within a control packet the frequency and time offset of the currently tuned station relative to a predetermined zero offset station; and

encoding within a control packet a list of other station frequencies and the time offset for each other station,

each receiver determining from the control packets the frequency and time offset of the station that will next transmit a message to the receiver.

8. In a time division multiplexed communication system for transmitting periodic frames of a first duration subdivided into subframes having time slots of a second duration, the subframes and time slots having unique identification numbers, the system including receivers each assigned an address that includes a unique number as one portion of the address and a subframe and time slot identification number as another portion, apparatus comprising:

means for encoding data into digital data packets bearing a time slot identification number, each packet of substantially equal duration to a time slot;

means for encoding format information within the data packet which alerts receivers assigned the time slot number as a portion of their address that more than one message is contained in the packet;

means for placing the messages in predetermined positions within the packet to be recognized by the alerted receivers as multiple messages; and

means for encoding within each message an address that corresponds to the unique numbered portion of the receiver address so that only the intended receiver reads the message.

9. The apparatus of claim 8 including means for formatting information within the message to tell the addressed receiver that the information therein is either an actual data message or is a pointer to a target time slot where the data message can be found.

10. The apparatus of claim 9 in which the formatting means transmits the actual data messages as binary numbers corresponding to predetermined messages.

11. In a time division multiplexed communication system having a transmitter system comprising a plurality of stations transmitting on different frequencies digital data packets to a plurality of receivers each having an address, apparatus for increasing the number of individual receivers that can be served by a single transmitter system, comprising:

means for encoding format information in a data packet uniquely addressed to a receiver within the transmitter system indicating that the data therein is receiver control information rather than message information;

means for encoding in the receiver control information the identification of stations within the transmitter system to which the addressed receiver must tune for message information;

means for transmitting the data packet from all stations within the transmitter system to alert the addressed receiver to tune to any of the identified stations; and

means for transmitting from the identified stations to the addressed receiver the data packets having message information.

12. The apparatus of claim 11 in which the means for encoding the identification of stations comprises means for identifying each station by a time offset that corresponds to the station'"'"'s frequency in a list of frequencies and offsets known to the receiver.

13. In a time division multiplexed communication system having a plurality of transmitter systems each comprising a plurality of stations for transmitting on different frequencies digital data packets including system control packets to a plurality of receivers each having an address, apparatus for splitting the receivers in an area among several transmitter systems to increase the number of receivers that can be served, comprising:

means for encoding in a control packet a mask bit field corresponding to a predetermined portion of a receiver'"'"'s address;

means for encoding in a control packet an address field corresponding to the same portion of the receiver address; and

means for masking bits in the mask bit field to indicate the bits in the address field that must be matched by the corresponding portion of the receiver address for the receiver to be served by the transmitter system transmitting the control packet.

14. In a time division multiplexed communication system having a transmitter system comprising a plurality of stations for transmitting on different frequencies data packets including system control packets and message packets to a plurality of receivers each having an address, apparatus for improving the probability of reception of the message packet by the receiver, comprising:

means for offsetting the time of transmission of data packets from each station within the transmitter system so that the same data packets are transmitted at different relative times;

means for encoding within a control packet the frequency and time offset of the currently tuned station relative to a predetermined zero offset station; and

means for encoding within a control packet a list of other station frequencies and the time offset for each other station,

each receiver determining from the control packets the frequency and time offset of the station that will next transmit a message to the receiver.