Variable bitrate radio modem system to enhance data transmission and reduce error rates

• US 5,862,141 A
• Filed: 06/14/1996
• Issued: 01/19/1999
• Est. Priority Date: 06/14/1996
• Status: Expired due to Term

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Trotter, John Andrew
• Primary Examiner(s): Pham, Chi H.
• Assistant Examiner(s): NGO, RICKY QUOC
• Application Number:
  US08/665,131
• Time in Patent Office: 949 Days
• Field of Search: 370/242, 370/252, 370/253, 370/333, 370/465, 370/545, 370/468, 375/220, 375/222, 375/225, 371/5.1, 371/5.2, 371/5.5, 455/556, 455/557
• US Class Current: 370/468
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication

Abstract

Disclosed is a variable bitrate radio modem unit that includes a transmit section and a receive section that are linked through a host computer. In the transmit section, the host computer is connected to a data modulator equipped with a variable bitrate data generator which in turn is connected to a radio transmit modem. In the receive section, a radio receive modem is connected to a clock/data recovery circuit which in turn is connected to an error detection and correction circuit. The error detection and correction circuit is then connected to the host computer. A connection is established at a predetermined bitrate between two host computers of two individual radio modem units. While data is being transmitted back and forth, the error rate of the data being received is determined by the error detection circuit. If the error rate is larger than a predetermined rate, the bitrate of the radio transmit modem of the transmitting unit is reduced. Conversely, if the error rate is smaller than a second predetermined rate, the bitrate of the radio transmit modem of the transmitting unit is increased.

Claims

1. A variable bitrate radio modem system, comprising:

a transmitter for transmitting data at a bitrate to a receiving device;

a receiver for receiving a bitrate control signal from said receiving device;

a processor connected to said transmitter for varying said bitrate at which said transmitter transmits data according to said bitrate control signal; and

a data modulator, within said transmitter and connected to said processor, equipped with a variable bitrate data generator varying said bitrate based on said bitrate control signal.

2. A system according to claim 1, wherein said transmitter comprises a radio transmit modem.

3. A system according to claim 1, wherein said receiver comprises a radio receive modem.

4. A variable bitrate radio modem system, comprising:

a receiver for receiving data transmitted at a bitrate by a transmitting device;

an error detection circuit for detecting an error rate of said data received by said receiver;

a processor for establishing a bitrate control signal based upon said error rate;

a transmitter for transmitting said bitrate control signal to said transmitting device; and

a data modulator within said transmitting device equipped with a variable bitrate data generator varying said bitrate based on said bitrate control signal.

5. A system according to claim 4, wherein said receiver receives said data at a first bitrate and said transmitter transmits data at a second bitrate.

6. A system according to claim 5, wherein said first bitrate and said second bitrate are equal.

7. A system according to claim 5, wherein said first bitrate and said second bitrate are different than one another.

8. A system according to claim 4, wherein said receiver comprises a radio receive modem.

9. A system according to claim 4, wherein said transmitter comprises a radio transmit modem.

10. A system according to claim 4, further comprising an error correction circuit.

11. A system according to claim 4, further comprising a clock/data recovery circuit connected to said receiver.

12. A variable bitrate radio modem system, comprising:

a transmitter transmitting first data and a first bitrate control signal at a first bitrate to a remote device;

a receiver receiving second data and a second bitrate control signal transmitted by said remote device at a second bitrate;

a data modulator within said transmitter equipped with a variable bitrate data generator varying said first bitrate based on said second bitrate control signal;

an error detection circuit within said receiver detecting an error rate of said second data received by said receiver; and

a processor connected to said variable bitrate data generator and said error detection circuit establishing said first bitrate control signal based upon said error rate.

13. A system according to claim 12, wherein said first bitrate and said second bitrate are different than one another.

14. A system according to claim 12, further comprising an error correction circuit.

15. A system according to claim 12, further comprising a clock/data recovery circuit within said receiver recovering said second data using said first bitrate control signal.

16. A system according to claim 12, wherein said transmitter comprises a radio transmit modem.

17. A system according to claim 12, wherein said receiver comprises a radio receive modem.

18. A method of enhancing the transmission of data from a first radio modem unit to a second radio modem unit, said method comprising the steps of:

(a) establishing a communications link between said first radio modem unit and said second radio modem unit;

(b) transmitting a packet of data and a first bitrate control signal from said first radio modem unit to said second radio modem unit at a bitrate set at a predetermined level based on a second bitrate control signal which indicates said bitrate;

(c) receiving said packet of data and said first bitrate control signal at said second radio modem unit, recovering said packet of data using said second bitrate control signal which indicates said bitrate, and determining an error rate of said packet of data received by said second radio modem unit;

(d) increasing said bitrate by a predetermined amount if said error rate is greater than a predetermined upper threshold;

(e) decreasing said bitrate by a predetermined amount if said error rate is less than a predetermined lower threshold;

(f) transmitting said second bitrate control signal which indicates said bitrate from said second radio modem unit to said first radio modem unit, and transmitting another packet of data from said first radio modem unit to said second radio modem unit at said bitrate; and

(g) repeating steps c, d, e, and f until all of said data has been transmitted.

19. A method of enhancing the transmission of data from a first radio modem unit to a second radio modem unit, said method comprising the steps of:

(a) establishing a communications link between said first radio modem unit and said second radio modem unit;

(b) transmitting a packet of data and a first bitrate control signal from said first radio modem unit to said second radio modem unit at a bitrate set at a predetermined level based on a second bitrate control signal which indicates said bitrate;

(c) receiving said packet of data and said first bitrate control signal at said second radio modem unit, recovering said packet of data using said second bitrate control signal which indicates said bitrate, and determining an error rate of said packet of data received by said second radio modem unit;

(d) increasing said bitrate by a predetermined amount if said error rate is greater than a predetermined upper threshold for longer than a predetermined time interval;

(e) decreasing said bitrate by a predetermined amount if said error rate is less than a predetermined lower threshold for longer than a predetermined time interval;

(f) transmitting said second bitrate control signal which indicates said bitrate from said second radio modem unit to said first radio modem unit, and transmitting another packet of data from said first radio modem unit to said second radio modem unit at said bitrate; and

(g) repeating steps c, d, e, and f until all of said data has been transmitted.

20. A variable bitrate radio modem system, comprising:

a transmitter which transmits first data and a first bitrate control signal at a first bitrate to a remote device;

a data modulator within said transmitter equipped with a variable bitrate data generator which varies said first bitrate based on a second bitrate control signal;

a receiver which (i) receives second data and said second bitrate control signal from said remote device, (ii) determines an error rate based on said second data, and (iii) generates an error rate signal based on said error rate;

a clock/data recovery circuit within said receiver which recovers said second data using said first bitrate control signal; and

a processor coupled to said transmitter and to said receiver which generates said first bitrate control signal based on said error rate signal.

21. A system according to claim 20, further comprising:

a radio transmit modem within said transmitter.

22. A system according to claim 20, further comprising:

a radio receive modem within said receiver.

23. A system according to claim 20, further comprising:

an error detection and correction circuit within said receiver which determines said error rate of said second data.

24. A system according to claim 20, wherein said first bitrate and said second bitrate are equal.

25. A system according to claim 20, wherein said first bitrate and said second bitrate are different than one another.