Base Station Control Device Frequency Offset Synchronization
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Solution Overview
Problem
In wireless communication systems where multiple base stations transmit to multiple mobile stations at the same time and frequency, existing methods struggle to perform frequency offset compensation, leading to degraded reception characteristics due to oscillator frequency errors between base stations.
Innovation Solution
A base-station control device collects frequency offset data from mobile stations and calculates phase rotation amounts for each base station to ensure that the frequency offsets of their transmission signals are synchronized, allowing for equal frequency errors across all base stations communicating with a mobile station.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If frequency offset compensation is performed individually for each mobile station channel, then frequency offset can be cancelled for single mobile station communication, but multiple base stations cannot transmit to multiple mobile stations at the same time and same frequency
Solution Approach 1:
The patent changes the frequency offset parameter from being individually compensated per channel to being uniformly applied across all base stations. By determining a common frequency offset value and applying it to all base stations' transmission signals, the system enables coordinated multi-point transmission while maintaining frequency synchronization, thus improving both productivity and reliability
Solution Approach 2:
The patent creates a universal frequency offset compensation mechanism that serves all base stations and mobile stations simultaneously. Instead of having separate compensation processes for each channel, a single frequency offset value is determined and applied universally across the entire system, enabling multiple base stations to transmit to multiple mobile stations at the same time and frequency
2Measurement precision
If different phase rotation amounts are used for different mobile stations, then individual frequency offset compensation is achieved, but base stations cannot perform phase rotation with a unified phase rotation amount
Solution Approach 1:
The patent merges the individual frequency offset compensation processes into a single unified process. By combining the frequency offset information from all base stations and determining a common phase rotation amount, the system simplifies the control mechanism while maintaining accurate frequency offset compensation for all mobile stations
Solution Approach 2:
The patent changes the phase rotation parameter from being individually customized for each mobile station to being uniformly applied across all base stations. This parameter change simplifies the control operation while maintaining the ability to accurately compensate for frequency offsets through the common phase rotation amount
3Productivity
If multiple base stations transmit at the same frequency, then system capacity is improved, but frequency offsets from different oscillators cause signal degradation
Solution Approach 1:
The patent converts the harmful frequency offset interference into a beneficial uniform frequency characteristic. By deliberately applying a common phase rotation amount to all base stations, the patent transforms the originally harmful frequency offsets into a unified frequency reference, causing all transmitted signals to have the same frequency offset that can be easily compensated by mobile stations
Solution Approach 2:
The patent changes the frequency offset parameter from a random, base-station-specific value to a controlled, uniform value across all base stations. This parameter change eliminates the harmful interference caused by different frequency offsets while preserving the system capacity benefits of multiple base stations transmitting at the same frequency
Data Source
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AI summary
To provide a control station 40 serving as a base-station control device that issues an operation instruction to each of base stations 10 in a wireless communication system 50 in which a plurality of base stations 10 (101, 102, ...) perform transmission at the same time and the same frequency, wherein a frequency offset of a reception signal from a mobile station 30 (301, 302, ...) that is detected by each of the base stations 10 is collected, and a phase rotation amount that is a rotation amount when the base stations 10 rotate a phase of a transmission signal is determined for each of the base stations 10 so that frequency offsets of the respective transmission signals having been subjected to phase rotation by the respective base stations 10 are the same.