Multi-Carrier AFC Synchronization With Shared Clock Compensation
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Solution Overview
Problem
In wireless communication devices using carrier aggregation, frequency error values between carriers can differ due to cell tower-to-carrier mapping and Doppler rate, requiring separate automatic frequency corrections (AFCs) for each receiver path, which is inefficient, especially for single radio frequency (RF) transceiver implementations.
Innovation Solution
A synchronization controller estimates frequency errors for both receiver paths and determines AFCs to target either a shared clock or exclusively local clocks, synchronously applying these corrections to minimize phase locked loops and optimize frequency synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate automatic frequency corrections (AFCs) are used for each receiver path, then frequency error compensation accuracy is improved, but device complexity and hardware requirements increase
Solution Approach 1:
The patent merges the frequency correction functions by having the first AFC target a shared clock that is common to both receiver paths. This consolidation reduces the number of separate phase-locked loops needed while maintaining frequency synchronization accuracy across both paths through the shared clock mechanism.
Solution Approach 2:
The shared clock serves multiple functions simultaneously - it acts as the frequency reference for both the first and second receiver paths, and is targeted by the first AFC to compensate for frequency errors affecting both paths. This multi-functionality eliminates the need for separate dedicated clocks and AFCs for each path.
2Device complexity
If a shared clock is targeted by the first AFC, then hardware complexity is reduced, but frequency correction accuracy for the second receiver path may be compromised
Solution Approach 1:
The patent introduces a compensating AFC (second AFC) that targets the second receiver path's local clock or signal processing stage. This intermediary correction mechanism compensates for any frequency errors that the shared clock-based first AFC cannot address, thereby maintaining accuracy for the second path while still benefiting from the hardware reduction achieved by sharing the clock.
Data Source
AI summary
A method and system provides an automatic frequency correction (AFC) within a wireless communication device. A synchronization controller estimates first and second frequency errors respectively associated with a first received signal corresponding to a first receiver path and a second received signal corresponding to a second receiver path. The synchronization controller determines a value and a type of target clock of a first AFC associated with the first frequency error. If the first AFC is not generated to target a shared clock such as a reference clock, the synchronization controller generates a second AFC to compensate for the second frequency error. However, if it is determined that the first AFC targets a shared clock, the synchronization controller generates the second AFC to compensate for the first AFC and the second frequency error. The synchronization controller synchronously applies the first and second AFCs to the relevant clocks.