Data communication system having a speed setting variable with transmission quality factors

• US 4,991,184 A
• Filed: 12/18/1989
• Issued: 02/05/1991
• Est. Priority Date: 12/16/1988
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Hashimoto, Shinji
• Primary Examiner(s): Safourek, Benedict V.
• Application Number:
  US07/452,071
• Time in Patent Office: 414 Days
• Field of Search: 375/7, 375/8, 375/13, 375/34, 375/37, 375/58, 375/106, 375/109, 375/121, 370/24, 370/84, 455/52, 455/68, 455/69, 371/5.1, 371/5.5, 371/30, 371/32, 371/43, 371/46
• US Class Current: 375/219
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0015 characterised by the adaptation strategy
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/0054 Maximum-likelihood or sequential decoding, e.g. Viterbi, Fano, ZJ algorithms
• CPC Class Codes: H04L 1/16 in which the return channel carries supervisory signals, e.g. repetition request signals
• CPC Class Codes: H04L 1/206 for modulated signals

Abstract

In a full-duplex data communication system, the signal-to-noise ratio, error rate and occurrences of out-of-sync condition of signals transmitted on the data channel of a first transmission medium from a first station to a second station are detected by the latter and a first set of quality signals of the first transmission medium is generated. The signal-to-noise ratio, error rate and occurrences of out-of-sync condition of signals transmitted on the data channel of a second transmission medium in the opposite direction are likewise detected by the first station and a second set of quality signals of the second transmission medium are generated. The first set of quality signals are modulated and transmitted on a control channel of the second transmission medium from the second station and received and demodulated by the first station, which derives a speed setting command signal from the second set of quality signals as well as from the first set of quality signals represented by the demodulated signals, and the transmission speed of the first station is controlled according to the speed setting command signal. The speed setting command signal is modulated and transmitted on a control channel of the first transmission medium from the first to second station, which demodulates it and controls its transmission speed according to the demodulated speed setting command signal.

Claims

1. A data communication system comprising:

a first data-channel modulator having a variable speed setting connected to one end of a first transmission medium, and a second data-channel modulator having a variable speed setting connected to the other end ot the first transmission medium;

a first data-channel demodulator having a variable speed setting connected to one end of a second transmission medium, and a second data-channel demodulator having a variable speed setting connected to the other end of said transmission medium;

first signal-to-noise quality detector means for detecting a signal-to-noise ratio of said first transmission medium, and second signal-to-noise quality detector means for detecting a signal-to-noise ratio of said second transmission medium;

first error rate quality detector means for detecting an error rate of said first transmission medium, and second error rate quality detector means for detecting an error rate of said second transmission medium;

first out-of-sync quality detector means for detecting occurrences of out-of-sync condition on said first transmission medium, and second out-of-sync quality detector means for detecting occurrences of out-of-sync condition on said second transmission medium;

control means for deriving a speed setting command signal from a first set of output signals from said first signal-to-noise ratio quality detector means, said first error rate quality detector means and said first out-of-sync quality detector means as well as from a second set of output signals, and controlling the speed settings of said first data-channel modulator and said first data-channel demodulator according to said speed setting command signal;

a first control-channel modulator for modulating said speed setting command signal and transmitting the modulated command signal on said first transmission medium;

a second control-channel demodulator for demodulating the modulated speed setting command signal transmitted on said first transmission medium and controlling the speed settings of said second data-channel modulator and said second data-channel demodulator according to the demodulated speed setting command signal;

a second control-channel modulator for modulating output signals of said second signal-to-noise ratio quality detector means, said second error rate quality detector means and said second out-of-sync detector means and transmitting the modulated signals on said second transmission medium; and

a first control-channel demodulator for demodulating signals transmitted on said second transmission medium and supplying the demodulated signals to said control means as said second set of output signals.

2. A data communication system comprising:

a first data-channel modulator having a variable speed setting connected to one end of a first transmission medium;

a first data-channel demodulator having a variable speed setting connected to one end of a second transmission medium;

a first sequential decoder for sequentially decoding a convolutional code contained in the output of the first data-channel demodulator;

first signal-to-noise quality detector means for detecting a signal-to-noise ratio of said first transmission medium from the output of said data-channel demodulator;

first error rate quality detector means for detecting an error rate of said first transmission medium from the sequentially decoded convolutional code;

first out-of-sync quality detector means for detecting training sequences on said first transmission medium from the sequentially decoded convolutional code;

control means for deriving a speed setting command signal from a first set of output signals from said first signal-to-noise ratio quality detector means, said first error rate quality detector means and said first out-of-sync quality detector means as well as from a second set of output signals, and controlling the speed setting of said first data-channel modulator and said first data-channel demodulator according to said speed setting command signal;

a first control-channel modulator for modulating said speed setting command signal and transmitting the modulated command signal on said first transmission medium;

a first control-channel demodulator for demodulating signals transmitted on said second transmission medium and supplying the demodulated signals to said control means as said second set of output signals;

a second data-channel modulator having a variale speed setting connected to the other end of said first transmission medium;

a second data-channel demodulator having a variable speed setting connected to the other end of said second transmission medium;

second signal-to-noise ratio detector means for detecting a signal-to-noise ratio of said second transmission medium form the output of said second data-channel demodulator;

a second sequential decoder for sequentially decoding a convolutional code contained in the output of the second data-channel demodulator;

second error rate quality detector means for detecting an error rate of said second transmission medium from the output of said second sequential decoder means;

second out-of-sync quality detector means for detecting training sequences on said second transmission medium from the output of said second sequential decoder means;

a second control-channel demodulator for demodulating the modulated speed setting command signal transmitted on said first transmission medium and controlling the speed settings of said second data-channel modulator and said second data-channel demodulator according to the demodulated speed setting command signal; and

a second control-channel modulator for modulating output signal of said second signal-to-noise ratio quality detector means, said second error rate quality detector means and said second out-of-sync detector means and transmitting the modulated signals on said second transmission medium.

3. A method for controlling the operating speed of a data communication system including first and second stations interconnected by first and second transmission mediums operating in a full-duplex mode, each of said transmission mediums having a data channel and a control channel, comprising the steps of:

(a) detecting a signal-to-noise ratio, an error rate and occurrences of out-of-sync condition of signals transmitted on the data channel of said first transmission medium and generating a first set of quality signals of said first transmission medium, and detecting a signal-to-noise ratio, an error rate and occurrences of out-of-sync condition of signals transmitted on the data channel of said second transmission medium and generating a second set of quality signals of said second transmission medium;

(b) modulating said first set of quality signals and transmitting the modulated signals on the control channel of said second transmission medium;

(c) demodulating signals transmitted on the control channel of said second transmission medium;

(d) deriving a speed setting command signal from said second set of quality signals detected by the step (a) as well as from the signals demodulated by the step (c) and controlling the transmission speed of said first station according to said speed setting command signal;

(e) modulating said speed setting command signal derived by by the step (d) and transmitting the modulated command signal on the control channel of said first transmission medium; and

(f) demodultating the modulated speed setting command signal transmitted on the control channel of said first transmission medium and controlling the transmission speed of said second station according to the demodulated speed setting command signal.

4. A method for controlling the operating speed of a data communication system including first and second stations, said first and second stations exchanging convolutional codes through data channels of first and second transmission mediums in a full-duplex mode, each of said transmission mediums having a control channel, comprising the steps of:

(a) demodulating convolutional codes transmitted on said first transmission medium and sequentially decoding the demodulated convolutional codes;

(b) demodulating convolutional codes transmitted on said second transmission medium and sequentially decoding the demodulated convolutional codes;

(c) detecting a signal-to-noise ratio of signals transmitted on said first transmission medium from the convolutional codes demodulated by the step (a), detecting an error rate and training sequences of signals transmitted on said first transmission medium from the convolutional codes decoded by the step (a), and generating a first set of quality signals of said first transmission medium;

(d) detecting a signal-to-noise ratio of signals transmitted on said second transmission medium from the convolutional codes demodulated by the step (b), detecting an error rate and training sequences of signals transmitted on said second transmission medium from the convolutional codes decoded by the step (b), and generating a second set of quality signals of said second transmission medium;

(e) modulating said first set of quality signals and transmitting the modulated signals on the control channel of said second transmission medium;

(f) demodulating signals transmitted on the control channel of said second transmission medium;

(g) deriving a speed setting command signal from said first set of quality signals detected by the step (c) as well as from the signals demodulated by the step (f) controlling the transmission speed of said first station according to said speed setting command signal;

(h) modulating said speed setting command signal derived by the step (g) and transmitting the modulated command signal on the control channel of said first transmission medium; and

(i) demodulating the modulated speed setting command signal transmitted on the control channel of said first transmission medium and controlling the transmission speed of said second station according to the demodulated speed setting command signal.