OFDM Receiver FFT Timing Adjustment for ISI Reduction

The patent applies dynamics by making the FFT timing adjustable rather than fixed. The receiver dynamically adapts the FFT timing based on channel delay profiles and interference conditions. Specifically, the system can shift the FFT timing window to align with different transmission points' signal arrivals, allowing optimal demodulation for each TP while minimizing ISI. This dynamic adjustment resolves the contradiction between maintaining stable serving cell demodulation and reducing interference from other TPs.

The patent changes the timing parameter of the FFT operation to optimize performance. By varying the start time and duration of the FFT window based on detected channel conditions and delay profiles, the system adapts to different transmission points. This parameter change allows the receiver to minimize ISI for non-serving cells while maintaining adequate performance for the serving cell, effectively resolving the contradiction between demodulation stability and interference reduction.

The patent segments the timing optimization process into distinct stages: first, the receiver identifies and locks onto the serving cell's timing; second, it detects channel delay profiles for other transmission points; third, it calculates optimal FFT timing shifts based on these profiles. This segmentation breaks down the complex multi-criteria optimization into manageable steps, reducing computational burden while maintaining performance. Each stage builds on the previous one, making the overall process more tractable.

The system employs self-service by using the received signals themselves to determine the optimal FFT timing. The receiver extracts channel delay profiles directly from the incoming signals and uses these profiles to automatically adjust its timing without requiring external control or complex predetermined algorithms. This self-determination simplifies the system architecture while achieving optimal demodulation performance for multiple TPs.

The patent extracts the timing information for each transmission point separately by detecting individual channel delay profiles. Instead of forcing all signals to align with a single reference, the system extracts and utilizes the specific arrival time characteristics of each TP. This extraction allows the FFT timing to be optimized for each signal's actual arrival pattern, reducing ISI for the earliest signal while maintaining adequate alignment for later-arriving signals through selective timing adjustment.

The system performs preliminary detection of channel delay profiles for all transmission points before finalizing the FFT timing decision. By提前 identifying the arrival patterns of multiple TPs, the receiver can make an informed decision about the optimal FFT timing that balances performance across all signals. This preliminary action prevents severe misalignment by anticipating the timing characteristics of all incoming signals before committing to a specific FFT window position.