Method and apparatus for coordinating transmission of short messages with hard handoff searches in a wireless communications system

• US 7,653,157 B2
• Filed: 03/02/2007
• Issued: 01/26/2010
• Est. Priority Date: 05/21/1998
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Glauser, Olivier, Tiedemann, Edward G. Jr.
• Primary Examiner(s): Bocure; Tesfaldet
• Application Number:
  US11/681,630
• Publication Number:
  US 20070153941A1
• Time in Patent Office: 1,061 Days
• Field of Search: 375/344, 375/354, 375/316, 375/295, 375/130, 375/141, 375/147, 375132-136, 375/377, 455436-444, 455/150.1, 4551821-1823, 370328-334, 370/335, 370/337, 370/442, 370/342
• US Class Current: 375/344
• CPC Class Codes: H04W 36/0088 Scheduling hand-off measurements
• CPC Class Codes: H04W 36/142 over the same radio air interface technology
• CPC Class Codes: H04W 52/56 Detection of errors of TPC bits

Abstract

A method and apparatus for coordinating the time at which a mobile station performs searches for alternative systems to which a hard handoff will occur. The mobile station receives a command which instructs the mobile station as to when to tune to alternative frequencies in order to search for indicates of the presence of an alternative system. In another system which includes the present invention, predetermined times are defined with respect to a reference point in time that is common to both the origination base station and a mobile station. The mobile station tunes to alternative frequencies to perform searches only during these predetermined times. In addition, the mobile station coordinates the transmission of reports, which indicate the results of searches for alternative systems such that these reports are only transmitted from the mobile station when the mobile station is tuned to the origination frequency.

Claims

1. A method for coordinating times at which a mobile station monitors alternative frequencies with times at which an origination base station transmits short messages, the method comprising:

a) determining at the origination base station when the mobile station will be tuned to receive frequencies other than an origination frequency; and

b) transmitting short messages only at times when the mobile station is known to be tuned to receive the origination frequency based on the knowledge of when the mobile station will be tuned to frequencies other than the origination frequency, the base station transmitting a signal commanding the mobile station to tune to an alternative frequency at a particular time, wherein a window is created during which said mobile station can cease receiving information over the origination frequency without any reduction in a total amount of data.

2. The method of claim 1, wherein determining at the origination base station when the mobile station will be tuned to receive frequencies other than the origination frequency includes sending a message which commands the mobile station to tune to a frequency other than the origination frequency at a predetermined time.

3. The method of claim 1, wherein determining at the origination base station when the mobile station will be tuned to receive frequencies other than the origination frequency includes sending a message which commands the mobile station to tune to a frequency other than the origination frequency at any time within a predetermined period in time.

4. The method of claim 1, wherein the mobile station identifies pilot signal offsets at which multipath signals are received by the mobile station from a base station targeted for handoff before executing the handoff.

5. The method of claim 1, wherein the mobile station narrows a search window over which the mobile station looks for multipath signal assignable for handoff.

6. A method for receiving and monitoring an origination frequency at times when an origination base station transmits short messages to the mobile station and for receiving and monitoring alternative frequencies at other times, the method comprising:

a) receiving in the mobile station commands from the origination base station indicating when the mobile station can be tuned to receive frequencies other than the origination frequency, wherein a window is created during which said mobile station can cease receiving information over the origination frequency without any reduction in a total amount of data; and

b) selecting times during which the mobile station will be tuned to frequencies other than the origination frequency based upon the commands received from the origination base station.

7. A base station for coordinating times at which a mobile station monitors alternative frequencies with times at which the base station transmits short messages, the base station comprising:

a) means for determining when the mobile station will be tuned to receive frequencies other than an origination frequency; and

b) means for transmitting short messages only at times when the mobile station is known to be tuned to receive the origination frequency based on the knowledge of when the mobile station will be tuned to frequencies other than the origination frequency, said means for transmitting is operable to transmit a signal commanding the mobile station to tune to an alternative frequency at a particular time, wherein a window is created during which said mobile station can cease receiving information over the origination frequency without any reduction in a total amount of data.

8. The base station of claim 7, further comprising:

means for sending a message which commands the mobile station to tune to a frequency other than the origination frequency at a predetermined time.

9. The base station of claim 7, further comprising:

means for sending a message which commands the mobile station to tune to a frequency other than the origination frequency at any time within a predetermined period in time.

10. The base station of claim 7, wherein the mobile station identifies pilot signal offsets at which multipath signals are received by the mobile station from a base station targeted for handoff before executing the handoff.

11. The base station of claim 7, wherein the mobile station narrows a search window over which the mobile station looks for multipath signal assignable for handoff.

12. A mobile station for receiving and monitoring an origination frequency at times when an origination base station transmits short messages to the mobile station and for receiving and monitoring alternative frequencies at other times, the mobile station comprising:

a) means for receiving commands from the origination base station indicating when the mobile station can be tuned to receive frequencies other than the origination frequency, wherein a window is created during which said mobile station can cease receiving information over the origination frequency without any reduction in a total amount of data; and

b) means for selecting times during which the mobile station will be tuned to frequencies other than the origination frequency based upon the commands received from the origination base station.

13. A computer program product comprising:

(a) instructions operative to cause a computer to determine at an origination base station when a mobile station will be tuned to receive frequencies other than an origination frequency; and

b) instructions operative to cause the computer to transmit short messages only at times when the mobile station is known to be tuned to receive the origination frequency based on the knowledge of when the mobile station will be tuned to frequencies other than the origination frequency, the base station transmitting a signal commanding the mobile station to tune to an alternative frequency at a particular time, wherein a window is created during which said mobile station can cease receiving information over the origination frequency without any reduction in a total amount of data.

14. The computer program product of claim 13, wherein the instructions operative to cause a computer to determine at the origination base station when the mobile station will be tuned to receive frequencies other than the origination frequency includes instructions operative to cause the computer to send a message which commands the mobile station to tune to a frequency other than the origination frequency at a predetermined time.

15. The computer program product of claim 13, wherein the instructions operative to cause a computer to determine at the origination base station when the mobile station will be tuned to receive frequencies other than the origination frequency include instructions operative to cause the computer to send a message which commands the mobile station to tune to a frequency other than the origination frequency at any time within a predetermined period in time.

16. The computer program product of claim 13, wherein the mobile station identifies pilot signal offsets at which multipath signals are received by the mobile station from a base station targeted for handoff before executing the handoff.

17. The computer program product of claim 13, wherein the mobile station narrows a search window over which the mobile station looks for multipath signal assignable for handoff.

18. A computer program product comprising:

a) instructions operative to cause a computer to receive in the mobile station commands from the origination base station indicating when the mobile station can be tuned to receive frequencies other than the origination frequency, wherein a window is created during which said mobile station can cease receiving information over the origination frequency without any reduction in a total amount of data; and

b) instructions operative to cause the computer to select times during which the mobile station will be tuned to frequencies other than the origination frequency based upon the commands received from the origination base station.

19. A base station for coordinating times at which a mobile station monitors alternative frequencies with times at which the base station transmits short messages, the base station comprising:

a) a determination module operative to determine when the mobile station will be tuned to receive frequencies other than an origination frequency; and

b) a transmitter operative to transmit short messages only at times when the mobile station is known to be tuned to receive the origination frequency based on the knowledge of when the mobile station will be tuned to frequencies other than the origination frequency, said means for transmitting is operable to transmit a signal commanding the mobile station to tune to an alternative frequency at a particular time, wherein a window is created during which said mobile station can cease receiving information over the origination frequency without any reduction in a total amount of data.

20. The base station of claim 19, wherein:

the transmitter is further operative to send a message which commands the mobile station to tune to a frequency other than the origination frequency at a predetermined time.

21. The base station of claim 19, further comprising:

the transmitter is further operative to send a message which commands the mobile station to tune to a frequency other than the origination frequency at any time within a predetermined period in time.

22. The base station of claim 19, wherein the mobile station identifies pilot signal offsets at which multipath signals are received by the mobile station from a base station targeted for handoff before executing the handoff.

23. The base station of claim 19, wherein the mobile station narrows a search window over which the mobile station looks for multipath signal assignable for handoff.

24. A mobile station comprising:

a) a receiver operative to receive commands from the origination base station indicating when the mobile station can be tuned to receive frequencies other than the origination frequency, wherein a window is created during which said mobile station can cease receiving information over the origination frequency without any reduction in a total amount of data; and

b) a selection module operative to select times during which the mobile station will be tuned to frequencies other than the origination frequency based upon the commands received from the origination base station.