Cellular telephone data communication system and method

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.

I 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. 
     
     
       2. The method of claim  1  which includes adding an error control correction data format to said data signal before providing said data signal to said modem. 
     
     
       3. A method of claim  1  which includes repetitively providing a unique data byte to said modem during a break in said data signal. 
     
     
       4. The method of claim  2  wherein the addition of said error control correction format involves 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, providing said data signal to said modem for transmission to said receiving station, examining the data words in each received data packet at the receiving station for error and determining which data words are acceptable, transmitting an acknowledgment signal to the transmitting station for each acceptable data word, determining from the transmitted acknowledgement 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. 
     
     
       5. The method of claim  4  which includes decreasing the size of subsequent data packets to be transmitted as the frequency of error in received data packets increases and increasing the packet size of subsequent data packets to be transmitted as the frequency of error in received data packets decreases. 
     
     
       6. The method of claim  4  which includes sensing a complete loss of said carrier signal for a predetermined period at said transmitting station and initiating said predetermined time period in response to said loss to maintain said modem in the activated state. 
     
     
       7. The method of claim  6  which includes causing said modem to disconnect and terminate transmission to said receiving station of all data packets if the signal is not resumed within said predetermined time period. 
     
     
       8. The method of claim  7  which includes operating said modem without a scrambler polynomial and continuously changing said data signal provided to said modem for modem synchronization. 
     
     
       9. The method of claim  8  which includes repetitively providing a unique data byte to said modem during a break in said data signal to prevent the modem from entering a static condition. 
     
     
       10. A method for transmitting data between a transmitting station and a receiving station 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, 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. 
     
     
       11. The method of claim  10  which includes decreasing the size of subsequent data packets to be transmitted as the frequency of error in received data packets increases and increasing the packet size of subsequent data packets to be transmitted as the frequency of error in received data packets decrease. 
     
     
       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 acknowledgement 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 sad 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 provide 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. 
     
     
       13. The signal processing interface of claim  12  wherein said modem means operates without a scrambler polynomial, said processing means operating to continuously change said data signal to provide synchronization for said modem means. 
     
     
       14. The signal processing interface of claim  13  wherein said processing means operates in response to a break in said data to repetitively provide a unique data byte to said modem means for the duration of said break in the data. 
     
     
       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 said 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. 
     
     
       16. The cellular telephone data communication system of claim  15  wherein the data signal format is formed by the signal processing and control means for the mobile or static signal processing interface means operating in the transmitting mode by 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, the signal processing and control means for the mobile or static signal processing interface means operating in the receiving mode being operative to receive and examine the data words in each transmitted data packet for error to determine which data words are acceptable and to transmit an acknowledgement signal for each acceptable data word to the transmitting mobile or static signal processing interface means, the signal processing and control means for the transmitting mobile or static signal processing interface means operating to receive and determine the frequency of error in said received data packets from said acknowlegment signals and to adjust the size of subsequent data packets to be transmitted in accordance with said error frequency. 
     
     
       17. The cellular telephone data communication system of claim  16  wherein the signal processing and control means for the transmitting mobile or static signal processing interface means operates to control the size of subsequent data packets inversely to the error frequency detected thereby. 
     
     
       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 therefrom, 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. 
     
     
       19. The data processing interface of claim  18  wherein said processing and control means determines from the acknowledgment signals which data packets were received with unacceptable errors and provides said data packets to said modem means for retransmission by said cellular telephone system. 
     
     
       20. The data processing interface of claim  19  wherein said modem means operates without a scrambler polynomial, said processing and control means operating to continuously change the data signal to provide synchronization for said modem means. 
     
     
       21. The data processing interface of claim  19  wherein said modem means operates without a scrambler polynomial, said processing and control means operating in response to a break in the data from said data source to repetitively provide a unique data byte to said modem means for the duration of said break in the data. 
     
     
       22. The data processing interface of claim  19  wherein said modem means is operative to disconnect from said cellular telephone system in response to a disconnect signal and inoperative to disconnect in response to a loss of a cellular telephone radio carrier signal, said processing and control means operating to provide a disconnect signal to said modem means when a delay period subsequent to a loss of said cellular radio carrier signal has elapsed without the resumption of said cellular telephone carrier radio signal. 
     
     
       23. The data processing interface of claim  22  which is operative in a receiving mode to receive a data signal transmitted by said cellular telephone system, said modem means receiving the data signal from said cellular telephone system and providing said data signal to said processing and control means, the processing and control means operating to examine the data words in each received data packet for error to identify acceptable data words and providing an acknowledgment signal to said cellular telephone system for each acceptable data word, the processing and control means operating to remove the error control correction data format from said data section. 
     
     
       24. The data processing interface of claim  23  wherein said modem means operates without a scrambler polynomial, said processing and control means operating to continuously change said data signal to provide synchronization for said modem means. 
     
     
       25. The data processing interface of claim  24  wherein said processing and control means operates in response to a break in the data from said data source to repetitively provide a unique data byte to said modem means for the duration of the break in said data. 
     
     
       26. A cellular computer data transmission interface device for allowing a portable computer having a conventional data output terminal to operate a mobile cellular telephone having a cellular transceiver linked via radio signals to a cellular system in response to bus- compatible control signals generated by a control unit in response to direct operator input and supplied to the cellular transceiver over a bus directly connected to the control unit and the cellular transceiver, comprising:    
       ( a )  receiving means for receiving instructions from the portable computer,    
       ( b )  processing means connected with said receiving means for interpreting the instructions received from the portable computer and for generating cellular transceiver control signals in response to said portable computer generated instructions,    
       ( c )  transmitting means connected with said processing means for receiving said cellular transceiver control signals, generating bus - compatible signals from said control signals, and for transmitting said bus compatible signals to the bus through a connection between the transmitting means and the bus to cause the cellular transceiver to place a cellular telephone network call.    
     
     
       27. The device of claim  26  wherein the receiving means for receiving instructions from the portable computer comprises a serial data interface.  
     
     
       28. The device of claim  26  wherein the transmitting means comprises an eight- bit parallel input/output cellular interface.    
     
     
       29. A cellular telephone data transmission interface device comprising interface means to connect to a cellular radiotelephone bus sensing means connected to the interface means for sensing digital cellular telephone control signals on control lines of the cellular bus, control signal generating means connected to the interface means for generating digital cellular telephone control signals and transmitting said digital cellular telephone control signals to the control lines of the cellular bus, and processing means connected to the sensing means and to the control signal generating means for receiving and evaluating the digital cellular telephone control signals sensed by the sensing means, wherein the processing means compares the sensed digital cellular telephone control signals to expected digital cellular telephone control signal values incorporated in said processing means and selects a first mode of operation of the control signal generating means enabling data transmission when the sensed digital cellular telephone control signals correspond to the expected digital cellular telephone control signal values and selects a second mode of operation of the control signal generating means if said sensed digital cellular telephone control signals do not correspond to said expected digital cellular telephone control signal values.  
     
     
       30. A cellular telephone data transmission interface device for use with a mobile cellular telephone of the type that has a cellular transceiver linked via radio signals to a cellular system in response to control signals generated by a control unit and supplied to the cellular transceiver over a bus directly connected to the control unit and the cellular transceiver, which allows an analog signaling device external to the mobile cellular telephone to transmit data signals to or receive data signals from the cellular transceiver using the cellular bus, so that the analog signaling device may transmit or receive data signals using the cellular system, comprising: 
       ( a )  bus interface means for connecting external devices to the cellular bus so that said external devices may transmit signals to or receive signals from the cellular transceiver,    
       ( b )  switching means for selectably connecting one or more external devices to the bus interface means with at least one of said external devices being the external analog signaling device, and    
       ( c )  control means for selectively controlling the operation of the switching means to connect the external analog signaling device to the bus interface means.    
     
     
       31. The device of claim  30  wherein the control means controls the operation of the switching means in response to a program internal to the device.  
     
     
       32. The device of claim  30  further comprising a computer interface means for receiving instructions from a portable computer, said interface means connected to the control means, wherein the control means controls the operation of the switching means in response to said received instructions.  
     
     
       33. The device of claim  30  wherein the switching means is an analog switch.  
     
     
       34. The device of claim  30  wherein the external analog signaling device is a modem.  
     
     
       35. A system for transferring data over a radio telephone network when directly connected to a radio telephone network access device for allowing external control of the radio telephone network access device, comprising: 
       
         computer means for providing and receiving data signals;  
       
       
         modem means operably connected to the computer means for modulating data signals received from said computer means for transmission over a radio telephone network access device and for demodulating data signals received from the radio telephone network access device for transmission to the computer means;  
       
       
         interface means connected between said modem means and the radio telephone network access device for transmitting data signals to and receiving data signals from the radio telephone network access device, said interface means providing parallel lines for connection to said radio telephone network access device, said lines including  
       
       
         a data transmit line for transmitting data signals from said modem means to the radio telephone network access device,  
       
       
         a data receive line for transmitting data signals from the radio telephone network access device to said modem means, and  
       
       
         plural control lines for providing digital control signals to the radio telephone network access device to control the operation of the device.  
       
     
     
       36. A system as defined in claim  35 , including a control means connected to said computer means, said interface means, and said modem means for controlling the radio telephone network access device to establish a telephone communication link and to enable data signal transmission over the radio telephone network.  
     
     
       37. The data transmission interface device of claim  26  wherein said receiving means further comprises data transfer means for transferring digital data between the portable computer and the cellular transceiver for transmission over the cellular transceiver to a remote station.  
     
     
       38. The data transmission interface device of claim  37  further comprising modem means operably connected to the data transfer means and the cellular transceiver for modulating data signals received from the portable computer for transmission over the cellular transceiver to the remote station and for demodulating data signals received from the radio telephone network access device for transmission to the computer means.  
     
     
       39. The system of claim  35  wherein the modem means modulates a voice band carrier using data signals received from said computer means for transmission over the radio telephone network access device and demodulates voice band data signals received from the radio telephone network access device for transmission to the computer means.