Configurable DFT Window for Single Carrier Waveform Data Transmission
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Solution Overview
Problem
Single carrier waveforms, such as DFT-s-FDM and SC-QAM, lack a natural DFT window, requiring periodic cyclic prefixes or guard intervals to prevent inter-symbol interference, which adds overhead and reduces system efficiency.
Innovation Solution
Implementing a mixed symbol structure where data is transmitted without a cyclic prefix or guard interval, while reference signals use a fixed DFT window with a cyclic prefix or guard interval, allowing for a configurable DFT window and overlapping FFT windows to maintain system flexibility and reduce overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cyclic prefix or guard interval is introduced periodically into the transmitted single carrier waveform signal, then inter-symbol interference is protected against, but overhead is increased
Solution Approach 1:
The transmitted signal is segmented into different symbol types: reference signal symbols with cyclic prefix/guard interval for reliability, and data symbols without cyclic prefix/guard interval for efficiency. This segmentation allows different parts of the signal to serve different functions optimally.
Solution Approach 2:
Different quality levels are applied locally to different signal components. Reference signal symbols receive the full protection of cyclic prefix or guard interval, while data symbols use a simplified approach with configurable DFT window and overlapping FFT windows, optimizing the trade-off between reliability and efficiency for each component.
2Reliability
If a cyclic prefix or guard interval is used, then timing inaccuracies are compensated, but system efficiency is reduced
Solution Approach 1:
The system dynamically adjusts the DFT window configuration and overlapping FFT window parameters based on channel conditions and timing requirements. This allows the system to maintain reliability when needed while maximizing efficiency in other transmission segments.
Solution Approach 2:
The DFT window length and overlapping FFT window parameters are made configurable rather than fixed. This allows optimization of the balance between timing accuracy compensation and system efficiency based on specific transmission conditions and requirements.
3Measurement precision
If a fixed DFT window is used for reference signals, then channel estimation is improved, but flexibility is reduced
Solution Approach 1:
The signal is divided into reference signal symbols with fixed DFT window for precise channel estimation and data symbols with configurable DFT window for flexibility. This segmentation allows both precision and adaptability to coexist in different parts of the transmission.
Solution Approach 2:
The reference signal symbols with fixed DFT window serve multiple functions: channel estimation, timing synchronization, and as a basis for deriving the configurable DFT window parameters for data symbols. This multi-functionality justifies the fixed structure while maintaining overall system flexibility.
Data Source
AI summary
In order to maintain flexible system bandwidth and a flexible center frequency, without requiring a cyclic prefix or guard interval, a transmitter apparatus transmits a reference signal based on a single carrier waveform having a mixed symbol structure, in reference signal symbols using at least one of a cyclic prefix and a guard interval and transmits data based on the single carrier waveform without the cyclic prefix or the guard interval. The data may be based on input data processed using overlapping FFT windows, and an amount of overlap between the FFT windows may be configurable by the transmitter or the receiver. An apparatus receiving the downlink transmission comprising data based on a single carrier waveform may process the data based on overlapping FFT windows.