Method and circuit for acquisition by a radio receiver

• US 5,711,001 A
• Filed: 05/29/1996
• Issued: 01/20/1998
• Est. Priority Date: 05/08/1992
• Status: Expired due to Term

• Current Assignee: Motorola Mobility, Inc. (Lenovo Group Ltd.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Binzel, Charles P., Bussan, Christopher F., Marry, Patrick J., Arora, Arvind S., Rabe, Duane C.
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): LE, THANH C
• Application Number:
  US08/657,694
• Time in Patent Office: 601 Days
• Field of Search: 455/33.1, 455/33.2, 455/33.4, 455/34.1, 455/34.2, 455/53.1, 455/54.1, 455/56.1, 455/62, 455/63, 455/161.1, 455/161.2, 455/161.3, 455/422, 455/432, 455/434, 455/435, 455/450, 455/452, 455/455, 379/59, 379/60
• US Class Current: 455/432.1
• CPC Class Codes: H03J 1/0091 provided with means for scanning over a band of frequencies H03J1/0058 takes precedence
• CPC Class Codes: H04W 48/20 Selecting an access point

Abstract

A method and associated circuitry for acquiring a channel of a set of frequency channels by a radio receiver. The radio receiver scans selected control channels and measures the power levels of signals generated upon the respective ones of the control channels and stores values. An attempt to effectuate a communication link with a transmitter which transmits a data signal upon one of the control channels is only attempted if the measured power level on such control channel increases beyond a certain amount. The tuning frequency of the tuning circuitry can be retuned when the tuning circuitry is initially tuned to receive a communication signal transmitted by a transmitter of a less-than-most desired network of transmitters according to a second embodiment.

Claims

1. A method for camping a radio receiver to receive a communication signal transmitted upon a channel of a set of channels defined upon a frequency band by a transmitter of a group of remotely-positioned transmitters, said method comprising the steps of:

(a) measuring power levels of communication signals transmitted upon individual ones of channels of a set of channels;

(b) selecting channels upon which communication signals are transmitted of measured power levels above at least a minimum power level to form a first subset of channels;

(c) after said step (b) determining whether a communication link is effectuated with transmitters which transmit communication signals upon the channels of the first subset of channels;

(d) storing measured power levels of channels;

(e) re-measuring power levels of communication signals transmitted upon the individual ones of the channels of the set of channels,

(f) selecting channels re-measured in said step (e) having communication signals exhibiting power levels above a level related to the previously measured power levels stored in said step (d),

(g) forming a second subset of channels using at least those channels selected in step (f),

(h) determining whether a communication link is effectuated between the radio receiver and individual ones of the transmitters which transmit communication signals upon the channels of the second subset of channels,

(i) when said step (f) determines that a communication link is effectuated, camping the radio receiver to a channel of the second subset of channels, and

(j) when said step (i) determines that a communication link is not effectuated, returning to step (d) of storing.

2. The method of claim 1 wherein the channels are frequency channel and wherein the method further comprises the step of (i) sequentially tuning circuitry of the radio receiver to each frequency channel of the set of frequency channels defined upon the frequency band.

3. The method of claim 1 wherein said step (a) of measuring power levels comprises the step of (al) measuring amplitudes of signals representative of the communication signals upon the individual ones of the channels.

4. The method of claim 1 wherein said step (d) comprises the step of (d1) storing values of measured power levels of individual ones of the channels measured during said step (a).

5. The method of claim 4 wherein said step (d1) of storing comprises the substep of (d1i) storing the measured power levels in a memory element.

6. The method of claim 1 wherein the minimum power level utilized during said step (b) of selecting channels to form the first subset of channels selects channels above a predetermined, absolute-valued noise floor.

7. The method of claim 1 wherein the minimum power level utilized during said step (b) is of a value corresponding to a predetermined value above a measured power level of the measured power levels of lowest magnitude.

8. The method of claim 1 wherein said step (h) of determining when a communication link is effectuated comprises the substeps of:

(h1) decoding the communication signals transmitted upon the channels of the selected subset of channels to form decoded signals; and

(h2) comparing portions of the decoded signal with data stored at the radio receiver.

9. The method of claim 1 further comprising the step of (k) delaying the re-measuring of said step (e) for a time period based on a time necessary to measure and attempt to establish a communication link.

10. The method of claim 1 wherein said step (f) of selecting channels which exhibit power levels above a level related to previously measured power levels comprises the substep of (f1) selecting channels upon which communication signals having measured power levels beneath a predetermined absolute-valued noise floor during the measuring of said step (a) exhibit an increase in power levels measured during the re-measuring of said step (c) to be above the predetermined, absolute-valued noise floor.

11. The method of claim 1 wherein said step (f) of selecting channels which exhibit power levels above a level related to previously measured power levels comprises the substep of (f1) selecting channels upon which communication signals exhibit power level increases above a predetermined amount of power level rise.

12. The method of claim 1, further comprising the steps of:

(k) initially camping the radio receiver to receive a communication signal transmitted by a transmitter of a network of remotely-positioned transmitters on one of the first subset of channels;

(l) when said step (k) initially camps to a less-than-most desired network of remotely-positioned transmitters, performing the steps of (d) through (j) to determine if the radio receiver later becomes in range of the most desired network of remotely-positioned transmitters and camping to a transmitter of the most desired network in said step (i).

13. The method of claim 1 wherein said step (f) of selecting channels which exhibit power levels above a level related to previously measured power levels comprises the substep of (f1) selecting channels upon which communication signals exhibit a power level above a predetermined value above a measured power level of the measured power levels of lowest magnitude.

22. The method of claim 1 wherein said step (f) of attempting to decode data on the channels of the subset to determine when a communication link is effectuated comprises the substeps of:

(f1) decoding the communication signals transmitted upon the channels of the subset of channels to form decoded signals; and

(f2) comparing portions of the decoded signal with data stored at the radio receiver.

14. In a cellular communication system having a plurality of spaced-apart base stations wherein each of the spaced-apart base stations transmits communication signals on a control channel of a set of control channels defined upon a frequency band, and a radio transceiver having tuning circuitry and being operative to receive a communication signal transmitted upon a control channel by a base station of the plurality of base stations when positioned within the transmission range of the base station, a method for tuning the tuning circuitry of the radio transceiver to a frequency channel of the set of frequency channels, said method comprising the steps of:

(a) measuring power levels of communication signals transmitted upon individual ones of frequency channels of a set of frequency channels;

(b) selecting frequency channels upon which communication signals are transmitted of measured power levels above at least a minimum power level to form a first subset of frequency channels;

(c) storing measured power levels of frequency channels;

(d) re-measuring power levels of communication signals transmitted upon the individual ones of the frequency channels of the set of frequency channels,

(e) selecting frequency channels re-measured in said step (d) having communication signals exhibiting power levels above a level related to the previously measured power levels stored in said step (c),

(f) forming a second subset of frequency channels using at least those frequency channels selected in step (e),

(g) determining whether a communication link is effectuated between the radio receiver and individual ones of the transmitters which transmit communication signals upon the frequency channels of the second subset of frequency channels, and

(h) when said step (g) determines that a communication link is effectuated, selecting tuning of the radio receiver to a frequency channel of the second subset of frequency channels.

15. The method of claim 14, further comprising the steps of:

(i) after said step (b), initially camping the radio receiver to receive a communication signal transmitted by a basestation of a network on one of the first subset of frequency channels;

(j) when said step (c) initially camps to a less-than-most desired network of remotely-positioned transmitters, performing the steps of (d) through (h) to determine if the radio receiver later becomes in range of the most desired network and camping to a transmitter of the basestation of the most desired network in said step (h).

16. A method for operating a radio receiver to receive a communication signal transmitted upon a channel of a set of channels defined upon a frequency band by a transmitter of a group of remote transmitters, said method comprising the steps of:

(a) initially measuring power levels of communication signals transmitted upon individual ones of channels of a set of channels;

(b) storing measured power levels of channels;

(c) re-measuring power levels of communication signals transmitted upon the channels,

(d) selecting channels re-measured in said step (c) having communication signals exhibiting power levels above a level related to the previously measured power levels stored in said step (b),

(e) forming a subset of channels using at least those channels selected in step (d),

(f) attempting to decode data on the channels of the subset to determine whether a communication link is effectuated between the radio receiver and individual ones of the transmitters, and

(g) when said step (f) determines that a communication link is effectuated, operating the radio receiver on a decodable channel.

17. The method of claim 16, further comprising the step of

(h) when said step (g) determines that a communication link is not effectuated, returning to step (b) of storing.

18. The method of claim 16 wherein the channels are frequency channels and wherein the method further comprises the step of (h) sequentially tuning circuitry of the radio receiver to each frequency channel of the set of channels defined upon the frequency band.

19. The method of claim 16 wherein said step of measuring power levels measures amplitudes of signals representative of the communication signals upon the individual ones of the channels.

20. The method of claim 16 wherein said step (b) comprises the step of (b1) storing values of measured power levels of individual ones of the channels measured.

21. The method of claim 20 wherein said step (b1) of storing comprises the substep of (b1i) storing the measured power levels in a memory element.

23. The method of claim 16, further comprising the step of:

(h) selecting channels initially measured in said step (a) upon which communication signals are transmitted of measured power levels above at least a minimum power level to form an initial subset of channels, and

(i) after said step (h), demodulating to determine whether a communication link is effectuated with transmitters which transmit communication signals upon the channels of the initial subset of channels.

24. The method of claim 23 wherein the minimum power level utilized during said step (h) of selecting channels to form the first subset of channels selects channels above a predetermined, absolute-valued noise floor.

25. The method of claim 23 wherein the minimum power level utilized during said step (h) is of a value corresponding to a predetermined value above a measured power level of the measured power levels of lowest magnitude.

26. The method of claim 16 further comprising the step of (h) delaying the re-measuring of said step (c) for a time period based on a time necessary to measure and attempt to establish a communication link.

27. The method of claim 16 wherein said step (d) of selecting channels which exhibit power levels above a level related to previously measured power levels stored in said step (b) comprises the substep of (d1) selecting channels upon which communication signals having previously measured and stored power levels beneath a predetermined absolute-valued noise floor exhibit an increase in power levels measured during the re-measuring of said step (c) to be above the predetermined, absolute-valued noise floor.

28. The method of claim 16 wherein said step (d) of selecting channels which exhibit power levels above a level related to previously measured power levels stored in said step (b) comprises the substep of (d1) selecting channels upon which communication signals exhibit power level increases above a predetermined amount of power level rise.

29. The method of claim 16 wherein said step (d) of selecting channels which exhibit power levels above a level related to previously measured power levels stored in said step (b) comprises the substep of (d1) selecting channels upon which communication signals exhibit a power level, when compared against a previously measured and stored power level, rises above a predetermined value above a measured power level of the measured power levels of lowest magnitude.

30. The method of claim 16, further comprising the steps of:

(h) initially operating the radio receiver to receive a communication signal transmitted by a transmitter of a network of remotely-positioned transmitters;

(i) when said step (h) initially operates on a less-than-most desired network of remotely-positioned transmitters, performing the steps of (c) through (g) to determine if the radio receiver later becomes in range of the most desired network of remotely-positioned transmitters and operating the radio receiver to receive a decodable channel from a transmitter of the most desired network.