Method and system for defining a search window based on a mobile station's direction of motion and speed
First Claim
1. A method of searching for a target spread spectrum signal transmitted by a target transmitter in a spread spectrum communication system, said method comprising:
- determining a direction of motion and speed of said mobile station relative to said target transmitter;
determining a previously-measured phase of said target spread spectrum signal, wherein said previously-measured phase was previously measured by said mobile station;
determining that said speed is greater than a first threshold value;
defining a search window such that a first portion of said search window is before said previously-measured phase and a second portion of said search window is after said previously-measured phase, wherein said first portion is larger than said second portion when said direction of motion is toward said target transmitter and said first portion is smaller than said second portion when said direction of motion is away from said target transmitter; and
said mobile station searching for a spread spectrum signal having a phase at said mobile station that is within said search window.
6 Assignments
0 Petitions
Accused Products
Abstract
A mobile station receives a target pilot signal transmitted by a target transmitter in a spread spectrum communication system and measures its phase. The mobile station then defines a search window to search for the target pilot signal at a later time. The mobile station defines the center point of the search window based on the previously-measured phase and the mobile station'"'"'s direction of motion and speed relative to the target transmitter. If the mobile station is moving toward the target transmitter, the center point is less than the previously-measured phase by an adjustment amount. If the mobile station is moving away from the target transmitter, the center point is greater than the previously-measured phase by an adjustment amount. The adjustment amount may depend on the mobile station'"'"'s speed. After the search window is defined, the mobile station uses the search window to search for the target pilot signal.
22 Citations
19 Claims
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1. A method of searching for a target spread spectrum signal transmitted by a target transmitter in a spread spectrum communication system, said method comprising:
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determining a direction of motion and speed of said mobile station relative to said target transmitter; determining a previously-measured phase of said target spread spectrum signal, wherein said previously-measured phase was previously measured by said mobile station; determining that said speed is greater than a first threshold value; defining a search window such that a first portion of said search window is before said previously-measured phase and a second portion of said search window is after said previously-measured phase, wherein said first portion is larger than said second portion when said direction of motion is toward said target transmitter and said first portion is smaller than said second portion when said direction of motion is away from said target transmitter; and said mobile station searching for a spread spectrum signal having a phase at said mobile station that is within said search window. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A mobile station, comprising:
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a communication receiver for receiving spread spectrum signals; a processor; data storage; and program instructions stored in said data storage and executable by said processor to perform functions comprising; (a) determining a direction of motion and speed of said mobile station relative to a target transmitter; (b) determining a previously-measured phase of a target spread spectrum signal transmitted by said target transmitter, wherein said previously-measured phase was previously measured by said mobile station; (c) defining a search window based on said direction of motion and speed, wherein most of said search window is before said previously-measured phase when said direction of motion is toward said target transmitter and said speed is greater than a first threshold value, and wherein most of said search window is after said previously-measured phase when said direction of motion is away from said target transmitter and said speed is greater than said first threshold value; and (d) controlling said communication receiver to search for a spread spectrum signal having a phase at said mobile station that is within said search window. - View Dependent Claims (16, 17, 18, 19)
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Specification