OFDM Cyclic Prefix Generation with Half Tone Offset
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Solution Overview
Problem
OFDM-based systems face inefficiencies due to direct current (DC) bias from local oscillator leakage, which increases computational burdens when implementing a half tone offset to mitigate signal distortion and inter-symbol interference (ISI), particularly in systems like LTE, OFDMA, and 5G communications.
Innovation Solution
The method involves applying a half tone offset to the OFDM symbol before generating the cyclic prefix, reducing computational complexity by performing complex operations on a smaller symbol size, rather than on a symbol with a prepended cyclic prefix, thereby reducing the size of the symbol and the complexity of the processing required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a half tone offset is applied to mitigate DC bias and signal distortion, then signal quality is improved, but computational complexity increases
Solution Approach 1:
The patent applies the half tone offset to the OFDM symbol before generating the cyclic prefix, performing the complex frequency shifting operation on the smaller symbol rather than on the larger symbol with prepended cyclic prefix. This preliminary action reduces computational complexity while maintaining signal quality improvement.
Solution Approach 2:
The patent separates the half tone offset application from the cyclic prefix generation process, treating them as distinct operations where the offset is applied first to the base symbol. This segmentation allows the complex operation to be performed on fewer samples, reducing overall computational burden.
2Reliability
If a cyclic prefix is prepended to reduce inter-symbol interference, then reliability is improved, but the size of the symbol increases
Solution Approach 1:
The patent performs the half tone offset application before cyclic prefix generation, so that the frequency shifting operation is applied only to the original symbol samples rather than to the extended symbol with cyclic prefix. This preliminary action maintains reliability while reducing the number of samples requiring complex processing.
3Reliability
If complex operations are performed on a symbol with prepended cyclic prefix, then complete signal processing is achieved, but power consumption increases
Solution Approach 1:
The patent applies the half tone offset to the OFDM symbol before generating the cyclic prefix, performing complex operations on the smaller symbol size. This preliminary action reduces the number of computational operations required, thereby reducing power consumption while maintaining complete signal processing through subsequent cyclic prefix generation.
Solution Approach 2:
The patent segments the signal processing into distinct stages: first applying half tone offset to the base symbol, then generating the cyclic prefix. This segmentation allows complex operations to be performed only on the necessary samples, reducing overall power consumption while maintaining processing completeness.
Data Source
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Figure 3A~3B
AI summary
Half tone offset may be utilized to mitigate signal distortion caused by DC bias within OFDM-based systems. In addition a cyclic prefix may be utilized within an OFDM-based system to mitigate inter-symbol-interference. Presented herein are techniques and methods to efficiently apply a cyclic prefix to an OFDM symbol with half tone offset for low power systems.