Method and apparatus for providing a communication link quality indication

• US 5,469,471 A
• Filed: 02/01/1994
• Issued: 11/21/1995
• Est. Priority Date: 02/01/1994
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Wheatley, Charles E. III
• Primary Examiner(s): Swann, Tod R.
• Application Number:
  US08/190,517
• Time in Patent Office: 658 Days
• Field of Search: 375/1, 375/205, 379/63, 455/226.2, 455/226.3, 455/233.1, 455/52.1, 455/25, 455/33.1, 455/67.5, 455/67.6, 455/67.7, 455/226.4, 342/359, 380/34, 367/119, 348/725
• US Class Current: 370/335
• CPC Class Codes: H04W 52/225 Calculation of statistics, e.g. average, variance
• CPC Class Codes: H04W 52/226 using past references to control power, e.g. look-up-table
• CPC Class Codes: H04W 52/54 Signalisation aspects of the TPC commands, e.g. frame structure

Abstract

A link quality improvement system for a cellular communication system in which portable units are used to facilitate communication of information signals between system users, via at least one cell-site, using code division multiple access spread spectrum communication signals. The system enables users to improve the quality of reverse communication links from the portable units to the cell-site by providing to each system user a link quality signal indicative of power received at the cell-site relative to an optimum level of received power. At a cell-site communicating with a portable unit associated with a particular system user, the portable unit transmitted power is measured as received at the cell-site. A command signal is generated at the cell-site and transmitted to the portable unit for adjusting portable unit transmitter power. The command signals are also accumulated in order to enable generation of a link quality signal in response thereto. In a preferred implementation the link quality signal is an audible interference signal inducing the system user to adjust orientation of the portable communication unit so as to improve signal quality on the reverse link.

Claims

1. In a communication system in which system users communicate information signals between one another via at least one cell-site using code division multiple access (CDMA) spread spectrum communication signals, a system for improving quality of signals transmitted to said at least one cell-site from a portable communication unit utilized by one of said system users, said cell-site and said portable communication unit each including a transmitter and a receiver wherein said receiver of said portable communication unit is operative to provide an output signal to said one system user, said system comprising:

first power measurement means, coupled to said cell-site receiver, for measuring signal power in each CDMA communication signal directed to said cell-site from said transmitter of said portable communication unit;

first power adjustment command generator means, coupled to said cell-site transmitter and to said first power measurement means, for generating a first set of power adjustment commands corresponding to deviations in power measurements of said first power measurement means from a first predetermined power level, said cell-site transmitter transmitting said first set of power adjustment commands;

means for generating a link quality signal at least partially in response to said first set of power adjustment commands; and

summing means for combining said link quality signal with said output signal provided to said one system user;

whereby in response to said link quality signal said one system user may adjust the position of said portable communication unit in order to improve said quality of said signals transmitted to said cell-site.

2. The signal quality improvement system of claim 1 wherein said means for generating said link quality signal is disposed within said portable communication unit and wherein said link quality signal is indicative of the level of signal power received at said cell-site relative to a predetermined optimum level, said means for generating a link quality signal being connected to said summing means.

3. The signal quality improvement system of claim 1 further including speech codec means for generating said output signal as an audible signal, and wherein said means for generating said link quality signal includes means for generating an audible link quality signal.

4. The signal quality improvement system of claim 3 wherein said means for generating said link quality signal includes noise generator means for producing a background noise signal, and further includes means for scaling said background noise signal in accordance with said first set of power adjustment commands.

5. The signal quality improvement system of claim 4 wherein said means for scaling includes:

microprocessor means for accumulating said first set of power adjustment commands and for producing a noise indicator gain signal in response thereto; and

means for multiplying said background noise signal by said noise indicator gain signal.

6. The signal quality improvement system of claim 1 wherein said means for generating said link quality signal is disposed within said cell-site, said cell-site transmitter including means for transmitting said link quality signals to said portable communication unit.

7. The signal quality improvement system of claim 6 wherein said means for generating said link quality signal includes a noise generator for producing a background noise signal, and further includes means for scaling said background noise signal in accordance with said first set of power adjustment commands.

8. The signal quality improvement system of claim 7 wherein said means for scaling includes:

microprocessor means for accumulating said first set of power adjustment commands and for producing a noise indicator gain signal in response thereto; and

means for multiplying said background noise signal by said noise indicator gain signal.

9. The signal quality improvement system of claim 1 further including signal processor means, disposed in said portable communication unit, for:

accumulating said first set of power adjustment commands into an accumulated set of power adjustment commands;

determining an average value corresponding to said accumulated set; and

comparing said average value with a predetermined gain control level setting, and, based on said comparison, generating a transmitter gain adjustment signal.

10. The signal quality improvement system of claim 9 further including:

microprocessor means for providing said link quality signal in response to said transmitter gain adjustment signal; and

amplifier means, operatively coupled to said transmitter of said portable communication unit, for receiving said transmitter gain adjustment signal, said amplifier means including means for varying signal power of said transmitter in accordance with said transmitter gain adjustment signal.

11. The signal quality improvement system of claim 5 wherein said microprocessor means includes means determining an average value of said first set of power adjustment commands, and further includes means for setting magnitude of said noise indicator gain signal in accordance with said average value wherein said magnitude is a function of said average value.

12. The signal quality improvement system of claim 2 further including amplifier means, coupled to said transmitter and said receiver of said portable communication unit, said amplifier means responsive to said first set of power adjustment commands directed to said portable communication unit, for adjusting transmission signal power of said portable communication unit.

13. In a communication system in which system users communicate information signals between one another via at least one cell-site using code division multiple access (CDMA) spread spectrum communication signals, a method for improving quality of signals transmitted to said at least one cell-site from a portable communication unit utilized by one of said system users, said cell-site and said portable communication unit each including a transmitter and a receiver wherein said receiver of said portable communication unit is operative to provide an output signal to said one system user, said method comprising the steps of:

measuring signal power in each CDMA communication signal directed to said cell-site from said transmitter of said portable communication unit;

generating a first set of power adjustment commands corresponding to deviations in power measurements of said first power measurement means from a first predetermined power level, said cell-site transmitter transmitting said first set of power adjustment commands;

generating a link quality signal at least partially in response to said first set of power adjustment commands; and

combining said link quality signal with said output signal provided to said one system user;

whereby in response to said link quality signal said one system user may adjust the position of said portable communication unit in order to improve said quality of said signals transmitted to said cell-site.

14. The method of claim 13 further including the step of generating said output signal as an audible signal, said step of generating said link quality signal including the step of generating an audible link quality signal.

15. The method of claim 14 wherein said step of generating said link quality signal includes the step of producing a background noise signal, and further includes the step of scaling said background noise signal in accordance with said first set of power adjustment commands.

16. The method of claim 15 wherein said step of scaling includes the steps of:

accumulating said first set of power adjustment commands and producing a noise indicator gain signal in response thereto; and

multiplying said background noise signal by said noise indicator gain signal.

17. The method of claim 13 further including the step of transmitting said link quality signals to said portable communication unit.

18. The method of claim 13 further including the steps of:

accumulating said first set of power adjustment commands into an average value,

comparing said average value with a predetermined gain control level setting, and, based on said comparison, generating a first transmitter gain adjustment signal.

19. The method of claim 18 further including the steps of:

compiling a table in which values of link quality signals are indexed as a function of corresponding values of transmitter gain adjustment signals, and

determining a value of said link quality signal from said table by using said first transmitter gain adjustment signal as an index into said table.

20. The method of claim 16 further including the steps of:

determining an average value of said first set of power adjustment commands, and

setting magnitude of said noise indicator gain signal in accordance with said average value, said magnitude being inversely related to said average value.

21. The method of claim 13 further including the step of adjusting transmission signal power of said portable communication unit in response to said first set of power adjustment commands.

22. A method of providing a communication link quality indication in a communication system having a cell-site and having a set of portable units wherein at least one of said set of portable communication units has a plurality of positions in relation to said cell-site, the method comprising the steps of:

measuring a power level of a signal received from a particular portable unit of said set of portable communication units;

comparing said measured power level to a desired power level and producing a power adjustment indication based on a difference between said measured power level and said desired power level;

providing to said particular portable unit said power adjustment indication;

accumulating at said particular portable unit a set of said power adjustment indications and producing an average value thereof; and

producing at said particular portable unit a communication link quality indication when said average value exceeds a predetermined threshold;

wherein the position of said particular portable communication unit is adjusted in relation to the cell-site in response to the communication link quality indication.

23. The method of claim 22 wherein said communication link quality indication is an audible noise signal.

24. The method of claim 23 wherein said audible noise signal increases in volume as said communication link quality indication further exceeds said predetermine threshold.

25. The method of claim 22 wherein said communication link quality indication is presented on a visible display.

26. The method of claim 22 wherein said communication link quality indication is an audible tone.

27. The method of claim 26 wherein said audible tone is periodic.

28. The method of claim 27 wherein the period of said periodic audible tone increases is a function of the amount by which said average value exceeds said predetermined threshold.

29. The method of claim 22 wherein said average value controls said power level of said signal received from said particular portable unit at said cell-site.

30. A portable radio that communicates in a wireless communication environment and has a communication link quality indication capability, the radio comprising:

a receiver section that receives signals from the wireless communication environment;

a first processor, coupled to the receiver, for processing the received signals to generate a gain adjust signal;

a second processor, coupled to the first processor, for generating a noise indicator signal in response to the gain adjust signal;

a random number generator for generating a number sequence; and

a first summer, coupled to the second processor and the random number generator, for generating the communication link quality indication in response to the noise indicator and the number sequence.

31. The radio of claim 30 and further including:

a speech codec, coupled to the first processor, for generating a speech signal;

a second summer, coupled to the speech codec and the first summer, for generating an audible output signal from the speech signal and the communication link quality indication; and

an audio transducer, coupled to the second summer, for emitting the audible output signal.

32. The radio of claim 30 wherein the number sequence is a pseudorandom number sequence.

33. A method for providing a communication link quality indication in a portable radio that communicates in a wireless communication environment, the method comprising the steps of:

receiving signals from the wireless communication environment;

generating a gain adjust signal in response to the received signals;

generating a noise indicator signal in response to the gain adjust signal;

generating a number sequence; and

summing the noise indicator and the number sequence to generate the communication link quality indication.

34. The method of claim 33 and further including the steps of:

generating a speech signal from a speech codec;

summing the speech signal and the communication link quality indication to generate an audible output signal; and

emitting the audible output signal through an audio transducer.