Received signal strength determination methods and systems

• US 6,006,077 A
• Filed: 10/02/1997
• Issued: 12/21/1999
• Est. Priority Date: 10/02/1997
• Status: Expired due to Term

• Current Assignee: Optis Wireless Technology, LLC (Brevet Capital)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Shull, Eric A.
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): RAMOS FELICIANO, ELISEO
• Application Number:
  US08/942,645
• Time in Patent Office: 810 Days
• Field of Search: 455/226.2, 455/226.4, 375/227, 375/317
• US Class Current: 455/226.2
• CPC Class Codes: H04B 17/21 for calibration; for correcting measurements
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements

Abstract

A signal strength for a received signal such as a radio signal transmitted over a communication network is determined. The signal strength measurement is compensated for non-linear characteristics of the receiver. The compensation is provided by taking two signal strength readings with the receiver set at two different, known, gain levels. The difference between the expected change in the signal strength and the change actually measured by the receiver is used to generate a compensated signal strength measurement A table of compensation factors is generated for each signal strength which is also utilized in generating the compensated signal strength measurement. The compensated signal strength measurement reading is transmitted to the communication network for use in mobile assisted handover.

Claims

1. A method for measuring a strength of a received signal comprising the steps of:

determining an expected strength of a signal strength measurement of the received signal;

obtaining a first signal strength measurement of the received signal from a receiver set at a first gain level;

obtaining a second signal strength measurement of the received signal from the receiver set at a second gain level if the expected strength at least meets a predetermined criteria; and

generating a compensated signal strength measurement characterizing the strength of the received signal based on the first signal strength measurement and the second signal strength measurement, wherein the compensated signal strength measurement is the first signal strength measurement if the expected strength at least meets a predetermined criterion.

2. A method according to claim 1 wherein the compensated signal strength measurement is compensated for non-linear characteristics of the receiver.

3. A method according to claim 2 wherein the second gain level is less than the first gain level.

4. A method according to claim 2 wherein the first and second signal strength measurements are logarithmic received signal strength indications.

5. A method for measuring a strength of a received signal comprising the steps of:

obtaining a first signal strength measurement of the received signal from a receiver set at a first gain level;

obtaining a second signal strength measurement of the received signal from the receiver set at a second gain level; and

generating a compensated signal strength measurement characterizing the strength of the received signal based on the first signal strength measurement and the second signal strength measurement, the compensated signal strength measurement being compensated for non-linear characteristics of the receiver;

wherein the step of generating a compensated signal strength measurement comprises the steps of;

determining an expected difference between the first signal strength measurement and the second signal strength measurement based on the first gain level and the second gain level;

generating the actual difference between the first signal strength measurement and the second signal strength measurement;

comparing the actual difference to the expected difference to provide a signal strength compensating factor; and

generating the compensated signal strength measurement based on the signal strength compensating factor.

6. A method according to claim 5 wherein the step of generating the compensated signal strength measurement based on the signal strength compensating factor comprises the step of summing the signal strength compensating factor and the first signal strength measurement to provide the compensated signal strength measurement.

7. A method according to claim 5 wherein the received signal is a radio communications signal from a communication network and further comprising the step following the summing step of:

transmitting the compensated signal strength measurement to the network for use in mobile assisted handover.

8. A method according to claim 5 wherein the step of generating the compensated signal strength measurement based on the signal strength compensating factor comprises the steps of:

obtaining a previously determined compensation factor associated with the second signal strength measurement; and

summing the signal strength compensating factor, the previously determined compensation factor associated with the second signal strength measurement and the first signal strength measurement to provide the compensated signal strength measurement.

9. A method according to claim 8 wherein the received signal is a radio communications signal from a communication network and further comprising the steps following the summing step of:

averaging the compensated signal strength measurement with an earlier compensated signal strength measurement to provide an averaged signal strength measurement; and

transmitting the averaged signal strength measurement to the network for use in mobile assisted handover.

10. The method of claim 8 further comprising the steps following said summing step of:

obtaining a previously determined compensation factor associated with the second signal strength measurement; and

adjusting the previously determined compensation factor associated with the second signal strength measurement based on the signal strength compensating factor to provide an updated compensation factor associated with the second signal strength measurement.

11. A system for measuring a strength of a received signal comprising:

a receiver capable of operating at a first gain and a second gain;

means for determining an expected signal strength of a next signal strength measurement of the received signal;

a received signal strength indication generating circuit electrically connected to the receiver which provides a signal strength indication corresponding to a strength of a signal received by the receiver; and

a compensated signal strength measurement generating circuit which characterizes the strength of the received signal based on a first signal strength measurement at the first gain and a second signal strength measurement at the second gain.

12. A system according to claim 11 wherein the compensated signal strength measurement generating circuit further comprises:

means for causing the receiver to operate at one of the first gain or the second gain.

13. A system according to claim 11 wherein the compensated signal strength measurement generating circuit compensates for non-linear characteristics of the receiver.

14. A system according to claim 13 wherein the signal strength indication is a logarithmic received signal strength indication.

15. A system for measuring a strength of a received signal comprising:

a receiver capable of operating at a first gain and a second gain;

a received signal strength indication generating circuit electrically connected to the receiver which provides a signal strength indication corresponding to a strength of a signal received by the receiver;

a compensated signal strength measurement generating circuit which characterizes the strength of the received signal based on a first signal strength measurement at the first gain and a second signal strength measurement at the second gain; and

wherein the compensated signal strength measurement generating circuit comprises;

means for determining an expected difference between the first signal strength measurement and the second signal strength measurement;

means for generating an actual difference between the first signal strength measurement and the second signal strength measurement;

means for comparing the actual difference to the expected difference to provide a signal strength compensating factor; and

means for generating a compensated signal strength measurement based on the signal strength compensating factor.

16. A system according to claim 15 wherein the means for generating a compensated signal strength measurement based on the signal strength compensating factor comprises means for summing the signal strength compensating factor and the first signal strength measurement to provide the compensated signal strength measurement.

17. A system according to claim 15 wherein the received signal is a radio communications signal from a communication network and further comprising:

means for transmitting the compensated signal strength measurement to the network for use in mobile assisted handover.

18. A system according to claim 15 wherein the means for generating a compensated signal strength measurement based on the signal strength compensating factor comprises:

means for obtaining a previously determined compensation factor associated with the second signal strength measurement; and

means for sumniming the signal strength compensating factor, the previously determined compensation factor associated with the second signal strength measurement and the first signal strength measurement to provide the compensated signal strength measurement.

19. A system according to claim 18 wherein the received signal is a radio communications signal from a communication nework and further comprising:

means for averaging the compensated signal strength measurement with an earlier compensated signal strength measurement to provide an averaged signal strength measurement; and

means for transmitting the averaged signal strength measurement to the network for use in mobile assisted handover.

20. A system according to claim 18 further comprising:

memory means for storing a previously determined compensation factor associated with the second signal strength measurement; and

means for adjusting the previously determined compensation factor associated with the second signal strength measurement based on the signal strength compensating factor and for storing the adjusted previously determined compensation factor associated with the second signal strength measurement in the memory means.