OFDM Signal Transmitter IFFT Cyclic Prefix Memory Reduction
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Solution Overview
Problem
In OFDM systems, the addition of a cyclic prefix at the transmission end results in time delays and increased memory usage due to the need to store and read all result values of the inverse fast Fourier transform (IFFT), which affects data processing capability.
Innovation Solution
A signal transmitting apparatus and method that utilize a first memory for re-ordering data, an IFFT unit storing a twiddle factor for shifting output by the cyclic prefix size, a second memory for storing the cyclic prefix data, and a multiplexer to generate OFDM symbols, reducing time delay and memory use without altering hardware or power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all result values of IFFT are stored in memory to add cyclic prefix, then the cyclic prefix can be correctly added, but time delay increases and memory usage increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing only the necessary cyclic prefix portion in a separate memory buffer before the IFFT operation completes. This allows the system to have the cyclic prefix ready for immediate insertion without waiting to store and re-read all IFFT result values, thereby reducing time delay while ensuring correct cyclic prefix addition.
2Reliability
If all result values of IFFT are stored in memory to add cyclic prefix, then the cyclic prefix can be correctly added, but memory usage increases
Solution Approach 1:
The patent extracts only the necessary cyclic prefix portion from the complete IFFT result set and stores it separately in a dedicated buffer. This extraction approach avoids the need to store all IFFT result values in memory, significantly reducing memory usage while maintaining the correctness of cyclic prefix addition by ensuring the required portion is preserved.
3Reliability
If all result values of IFFT are read to add cyclic prefix, then the cyclic prefix can be correctly added, but data processing capability decreases
Solution Approach 1:
The patent extracts and pre-stores only the cyclic prefix portion needed for signal processing, eliminating the need to read through all IFFT result values. This extraction strategy maintains correct cyclic prefix addition while significantly improving data processing capability by reducing the number of memory read operations required.
4Reliability
If additional memory is added to store IFFT result values, then cyclic prefix can be added, but device complexity increases
Solution Approach 1:
The patent extracts only the essential cyclic prefix data for separate storage in a minimal buffer, avoiding the need for large additional memory structures. This approach enables cyclic prefix addition capability while minimizing device complexity by storing only the necessary extracted portion rather than all IFFT results.
Data Source
AI summary
The present invention relates to a signal transmitting apparatus, a method thereof, and an inverse fast Fourier transform (IFFT) apparatus for a signal transmitting apparatus. A signal transmitting apparatus according to an embodiment of the present invention receives data, and performs inverse fast Fourier transform (IFFT) on the data on the basis of a twiddle factor for shifting output data by the size of a cyclic prefix. In addition, the signal transmitting apparatus sequentially stores data corresponding to the size of the cyclic prefix starting with initial data among the transformed data, and generates an OFDM symbol on the basis of the stored data and the transformed data. According to the embodiment of the present invention, it is possible to efficiently reduce a time delay and a memory use amount when a cyclic prefix is added at a transmitting end, without changing the size of hardware and power consumption.