W-CDMA System Acquisition Using Pilot Signal Timing Reference
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Solution Overview
Problem
Current wireless communication systems face challenges in minimizing system acquisition time, which is crucial for efficient resource allocation and power reduction in mobile stations, as they lack a timely timing reference during the scanning process, leading to prolonged AFC convergence times.
Innovation Solution
A system acquisition method in W-CDMA systems uses a detected pilot signal from a non-requested system as a timing reference for remaining candidate frequencies, reducing or eliminating the need for initial AFC window time, thereby accelerating the scanning process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a system acquisition scan is performed over multiple candidate frequencies without using a detected pilot signal as timing reference, then the scanning process is straightforward and simple, but the AFC convergence time is prolonged and system acquisition time increases
Solution Approach 1:
The patent applies preliminary action by detecting and decoding system information from a non-requested system before completing the full acquisition scan. The detected pilot signal from this intermediate system is then used as a timing reference for subsequent frequency scans, eliminating the need for AFC convergence at each frequency step and significantly reducing overall acquisition time.
2Speed
If the pilot signal of a non-requested system is used as timing reference for remaining candidate frequencies, then AFC window time is reduced or eliminated, but the system must decode information from a non-requested system which adds processing complexity
Solution Approach 1:
The patent converts the potentially harmful situation of detecting a non-requested system (which would normally be discarded as interference or unwanted signal) into a beneficial resource. By decoding the system information and using its pilot signal as a timing reference, the patent transforms what was previously wasted processing into a time-saving mechanism that accelerates the overall acquisition process.
3Measurement precision
If AFC window time is maintained for each candidate frequency to ensure accurate frequency convergence, then frequency acquisition accuracy is maintained, but system acquisition time increases
Solution Approach 1:
The patent introduces an intermediary element - the pilot signal from a non-requested system - that serves as a timing reference for subsequent frequency scans. This intermediary allows the system to skip the traditional AFC convergence process at each frequency step while still maintaining accurate frequency acquisition, because the timing reference provides the necessary synchronization information without requiring full AFC convergence.
Data Source
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AI summary
In one illustrative example, a system acquisition method suitable for use in W-CDMA utilizes a receiver having an automatic frequency control (AFC) circuit. A system acquisition scan is performed over a plurality of candidate frequencies in an RF band. During the system acquisition scan, a pilot signal of a system on one of the candidate frequencies is detected. When information of the system is successfully decoded, and the system is different from a requested system (e.g. not the RPLMN or HPLMN), the pilot signal of the system is assigned as a timing reference in the receiver for one or more remaining candidate frequencies of the system acquisition scan. Therefore, an AFC window time otherwise needed to converge on a remaining candidate frequency is not needed or reduced.