Cellular telephone data communication system and method
DCFirst Claim
1. A method for transmitting data from a transmitting station over a cellular telephone system to a receiving station by means of a modem connected to said cellular telephone system which is operative in an activated state to modulate a carrier signal for said cellular telephone system with a data signal, said method including the steps of placing said modem in the activated state, providing a data signal to said activated modem, maintaining said modem in the activated state for a predetermined time period after a loss of said carrier signal before permitting said modem to deactivate, and causing said modem to remain in said activated state after the loss of said carrier signal if said carrier signal resumes within said predetermined time period.
6 Assignments
Litigations
0 Petitions
Accused Products
Abstract
The cellular telephone data communication system and method involves the use of a mobile data processing interface and a cooperating static data processing interface to effectively transmit data over a cellular telephone system. Each data processing interface includes a processor which operates in the transmitting mode to add an error control correction data format to data received from an external data source. The data is divided into packets and provided to a modem which is uniquely operated to eliminate the action of the modem scramble system and to remain active in spite of a carrier signal loss. The modem is deactivated or disconnected by a disconnect signal from the processor, and when carrier signal loss occurs, this disconnect signal is provided only after the lapse of a delay period without the resumption of the carrier signal. The error control correction data format causes a receiver to evaluate the received data for error and to retransmit an acknowledgment signal for each acceptable packet of received data. In the absence of an acknowledgment signal, the processor will again provide a data packet to the modem for retransmission. Also, the processor will determine the frequency of error in the received data from the acknowledgment signals and subsequently adjust the data packet size in accordance with this error frequency.
257 Citations
28 Claims
- 1. A method for transmitting data from a transmitting station over a cellular telephone system to a receiving station by means of a modem connected to said cellular telephone system which is operative in an activated state to modulate a carrier signal for said cellular telephone system with a data signal, said method including the steps of placing said modem in the activated state, providing a data signal to said activated modem, maintaining said modem in the activated state for a predetermined time period after a loss of said carrier signal before permitting said modem to deactivate, and causing said modem to remain in said activated state after the loss of said carrier signal if said carrier signal resumes within said predetermined time period.
- 10. A method for transmitting data between a transmitting station and a receiving station .Iadd.using a cellular network .Iaddend.which includes dividing data to be transmitted into a plurality of data packets, each data packet including a plurality of data words, the number of data words in a data packet determining the size of the data packet, transmitting said data packets to the receiving station, examining the data words in each received data packet for error and determining which data words are acceptable, transmitting an acknowledgment signal to the transmitting station for each acceptable data .[.word.]. .Iadd.packet.Iaddend., determining from the transmitted acknowledgment signals which data packets were received with unacceptable errors and retransmitting said unacceptable data packets, and determining the frequency of error in said received data packets from said acknowledgment signals and adjusting the size of subsequent data packets to be transmitted in accordance with said error frequency.
- 12. A signal processing interface for communicating data from a data source over a cellular telephone system to a receiving means via a cellular telephone radio carrier signal comprising processing means connected to receive data from said data source, said processing means operating to form said data into a data signal format to be transmitted as a data signal, the data signal format including blocks of data, at least one acknowledgment signal to be retransmitted by said receiving means back to said processing means upon receipt of each of said data blocks, cellular telephone transmission means operative upon receipt of said data signal format to transmit said data signal to said receiving means, and modem means connected to said signal processing means and said cellular telephone transmission means and operative to receive said data signal containing said data signal format from said processing means and to provided said data signal for transmission to said cellular telephone transmission means, said modem means being operative to disconnect from said cellular telephone transmission means in response to a disconnect signal and inoperative to disconnect in response to a loss of said cellular telephone radio carrier signal, said processing means operating to provide a disconnect signal to said modem means when a delay period subsequent to a loss of said cellular telephone radio carrier signal has elapsed without the resumption of said cellular telephone radio carrier signal.
- 15. A cellular telephone data communication system for communicating data from a data source over a cellular telephone system having a mobile transceiver unit operative to transmit and receive cellular telephone signals and a plurality of fixed transceiver units connected to transmit signals over a conventional telephone line system comprising a mobile signal processing interface means connected to said mobile transceiver unit and operative to communicate data from a data source to said mobile transceiver unit for transmission via a cellular telephone radio carrier signal or to receive a transmitted data signal from said mobile transceiver unit, and a static signal processing interface means connected to said conventional telephone line system and operative to communicate data from a data source over said conventional telephone line system to one of said fixed transceiver units for transmission via a cellular telephone radio carrier signal to said mobile unit or to receive a transmitted data signal via said conventional telephone line system, each said mobile signal processing interface means and static signal processing interface means being operative in a transmitting or receiving mode while the other operates in the opposite mode and each including signal processing and control means connected to receive data from a respective data source in the transmitting mode, said signal processing and control means also being operative in the receiving mode to receive a data signal from the associated mobile transceiver unit or associated conventional telephone line system, and modem means connected to said signal processing and control means, the signal processing and control means of the mobile or static signal processing interface means operating in the transmitting mode being operative to receive data from the associated data source and to form data into a data signal format to be transmitted as a data signal to the modem means connected thereto, said modem means being operative to disconnect in response to a disconnect control signal and inoperative to disconnect in response to a loss of said cellular telephone radio carrier signal, the signal processing and control means operating to provide a disconnect control signal to the modem means connected thereto when a delay period subsequent to a loss of said radio carrier signal has elapsed without the resumption of said telephone radio carrier signal.
- 18. A data processing interface for operation in a transmitting mode for transmitting data from a data source over a cellular telephone system to a receiving means via a cellular telephone radio carrier signal comprising processing and control means connected to receive data from said data source, said processing and control means operating to form said data into a data signal format to be transmitted as a data signal, said data signal format including a plurality of data packets, each said data packet including a number of data and control words, the number of words in a data packet determining the size of the data packet, each said data packet including an error control correction data format having at least one acknowledgement section, the acknowledgement section adapted to be retransmitted by said receiving means as an acknowledgment signal when an acceptable data packet is received by said receiving means, and modem means connected to said processing and control means to receive said data signal therfrom, said modem means being operable to modulate said cellular telephone radio carrier signal with said data signal and to provide said modulated signal to said cellular telephone system, said modem means receiving the acknowledgment signals transmitted by the receiving means and operating to provide such acknowledgment signals to said processing and control means, the processing and control means determining from said acknowledgment signals the frequency of error in the received data packets and adjusting the size of subsequent data packets in the data signal in accordance with said error frequency.
-
26. An interface system for correcting error in digital data transmitted and received between first and second digital data processing units via a cellular radio telephone link established between (1) a mobile transceiver unit which is adapted to be interfaced with the first digital data processing unit and (2) one of a plurality of fixed transceiver units which are adapted to be interfaced with the second digital data processing unit, comprising:
-
(a) a mobile signal processing interface means adapted to be connected with the first data processing unit and the mobile transceiver unit for supplying in digital form the data transmitted from the second digital data processing unit via the cellular telephone system to the first digital data processing unit and for receiving in digital form data from the first digital data processing unit for transmission to the second digital data processing unit via the cellular telephone system; (b) a static signal processing interface means adapted to be connected between the second data processing unit and the one fixed transceiver unit for supplying in digital form the data transmitted from the first digital data processing unit via the cellular telephone system to the second digital data processing unit and for receiving in digital form data from the second digital data processing unit for transmission to the first digital data processing unit via the cellular telephone system;
wherein each of said mobile signal processing interface means and said static signal processing interface means includes;
microprocessor means for controlling respectively said mobile signal processing interface means and said static signal processing interface means, each said microprocessor means being programmed to form dividing means for dividing the data produced by the corresponding digital data processing unit into plural groups of digital data, forward error correction encoding means for generating and associating with each group of digital data an error correcting signal for transmission to the other of said mobile signal processing interface means and said static signal processing interface means, and forward error correcting decoding means for receiving the forward error correcting signal generated by the microprocessor of the other of said mobile signal processing interface means and said static signal processing interface means in association with each group of digital data received from the other of said mobile signal processing interface means and said static signal processing interface means and for using said forward error correcting signal to detect errors and to correct those errors in the associated group of digital data when the number of detected errors is below a predetermined amount. .Iaddend. .Iadd. - View Dependent Claims (27)
-
-
28. mobile transceiver unit is moving. .Iaddend. .Iadd.29. A data transmission system for transmitting data from a data source to a data receiver over a radiotelephone system in which errors may occur at a varying error rate, the data transmission occurring in a data stream comprising a plurality of data packets, with the radiotelephone system including at least one portable transceiver unit operative to transmit and receiver radiotelephone signals and a plurality of fixed transceiver units connected to receive signals from a conventional telephone line system and transmit the signals to the portable transceiver unit and also to receive signals from the portable transceiver unit and transmit the signals to the conventional telephone line system, with the data receiver including a protocol decoding circuit that is in signal communications connection with at least one of the fixed transceiver unit, comprising:
-
a portable signal processing interface means adapted to be connected to the portable transceiver unit and operative to transmit data from the data source to the portable transceiver unit, said portable signal processing interface means including a signal processing means for implementing an error-handling data transmission protocol, including an error compensation protocol portion which adapts signal formatting of the transmitted data stream to minimize the propagation of data errors beyond the protocol decoding circuit, said error compensation protocol portion being effective for frequencies of error of less than a predetermined error rate, and an error limiting protocol portion which is operationally effective to vary, in response to changes in the radiotelephone system error rate, the size of the data packets transmitted, thereby reducing the quantity of data affected by errors occurring at frequencies greater than said predetermined error rate, said error correction protocol portion operating at least when the radiotelephone system error rate exceeds said predetermined error rate. .Iaddend. .Iadd.30. The data transmission system of claim 29 wherein the error compensation protocol portion further includes a forward error correction protocol which is enabled to correct errors occurring at a specified frequency which is not greater than the error rate capacity of the error compensation protocol portion. .Iaddend. .Iadd.31. The data transmission system of claim 29 wherein the sizes of the packets transmitted are varied within predetermined limits during operation of the error correction protocol portion. .Iaddend. .Iadd.32. The data transmission system of claim 31 wherein the packet sizes are increased when the error rate of the radiotelephone system decreases, and decreased when the said error rate increases. .Iaddend. .Iadd.33. The data transmission system of claim 32 wherein a forward error correction protocol is included in the error compensation protocol portion to minimize the propagation of errors occurring at a specified frequency which is less than the predetermined error rate. .Iaddend.
-
Specification