Parallel Baseband Processing for Cell Search Synchronization
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Solution Overview
Problem
The overlap of frequency bands due to spectrum refarming in wireless communication systems leads to increased adjacent channel interference and co-channel interference, resulting in prolonged cell searching and synchronization times for mobile stations, which in turn increases battery power consumption and reduces standby and talk/data times.
Innovation Solution
A method involving frequency shifting and low-pass filtering of received signals to filter out adjacent carrier frequencies, followed by parallel baseband processing based on an adjacent carrier power criterion, adapted for detecting frequency correction bursts in multiple adjacent carrier frequencies, thereby reducing initial cell searching and synchronization times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spectrum refarming is implemented to increase frequency reuse and transmission capacity, then network capacity and frequency efficiency are improved, but adjacent channel interference and co-channel interference increase, leading to prolonged cell searching and synchronization times
Solution Approach 1:
The patent segments the frequency search process by dividing the frequency spectrum into multiple candidate frequencies and processing them in parallel. The mobile station divides the cell search task into independent frequency segments that can be searched simultaneously, reducing the total time required despite the presence of interference from spectrum refarming.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and storing frequency offset values and candidate frequency lists before the actual cell search. The mobile station prepares a list of candidate frequencies based on expected offsets from the serving cell, so that when cell search is needed, the device can immediately begin parallel processing without delay.
2Device complexity
If traditional sequential cell search methods are used in refarmed spectrum environments, then device complexity is kept low, but cell searching and synchronization times are prolonged, increasing battery power consumption
Solution Approach 1:
The patent prepares candidate frequency lists and frequency offset information in advance, storing them in the mobile station's memory. This preliminary preparation reduces the computational burden during actual cell search operations, allowing parallel processing without requiring complex real-time calculations, thus saving battery power.
Solution Approach 2:
The patent dynamically adjusts the cell search process by using measured frequency offsets from the serving cell to generate candidate frequency lists. The search process adapts to the specific radio environment, processing only the most likely candidate frequencies in parallel, which optimizes the balance between processing speed and energy consumption.
3Loss of time
If parallel processing of multiple carrier frequencies is implemented, then cell searching time is reduced, but device complexity and processing requirements increase
Solution Approach 1:
The patent segments the parallel processing task into independent frequency branches, where each branch processes a specific candidate frequency independently. This segmentation allows the use of simplified processing algorithms in each branch while achieving overall speedup through parallel execution, managing device complexity effectively.
Solution Approach 2:
The patent pre-generates candidate frequency lists based on frequency offset measurements from the serving cell. By preparing this information in advance, the patent reduces the complexity of real-time parallel processing, as the mobile station only needs to execute pre-planned search sequences rather than performing complex frequency analysis during the actual cell search.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces initial cell searching and synchronization times for GSM-capable mobile stations, enhancing user experience by minimizing battery drain and improving connectivity efficiency.
Implementation Method 1
low-pass filtering the frequency shifted received signal at a first cutoff frequency to filter out a plurality of adjacent carrier frequencies
Data Source
AI summary
Disclosed is an apparatus, method and computer program which frequency shifts a received signal by a first frequency value and low-pass filters the frequency shifted received signal at a first cutoff frequency to filter out a plurality of adjacent carrier frequencies. Parallel baseband processing is then performed on two or more adjacent carrier frequencies among the plurality of adjacent carrier frequencies based upon an adjacent carrier power criterion. In certain examples, the parallel baseband processing is adapted for detecting a frequency correction burst in two or more adjacent Global System for Mobile Communications carrier frequencies or an Enhanced Data Rates for Global System for Mobile Communications Evolution carrier frequencies.