OFDM Symbol Truncation With Receiver Zero Insertion
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Solution Overview
Problem
The existing OFDM scheme in communication systems has limitations in achieving higher transmission efficiency, particularly due to the presence of guard intervals that prevent the shortening of transmission time, and there is a need for a scheme that improves temporal efficiency while maintaining compatibility with current OFDM-based systems.
Innovation Solution
The STT-OFDM scheme truncates a portion of each OFDM symbol on the transmitting side and inserts zeros on the receiving side to maintain orthogonality, utilizing error correction codes to mitigate inter-carrier interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If guard intervals are inserted in OFDM symbols to suppress inter-carrier interference, then reliability is improved, but transmission time cannot be shortened and temporal efficiency deteriorates
Solution Approach 1:
The patent extracts and removes the guard interval (CP) from the OFDM symbol structure, transmitting only the useful data portion. This extraction eliminates the time loss while the receiver compensates by inserting zeros at the appropriate positions during processing, thus maintaining interference suppression without the transmission time penalty.
Solution Approach 2:
Instead of inserting guard intervals at the transmitter to prevent interference, the patent inverts the approach by having the receiver insert zero-padding to maintain orthogonality. The transmitter sends truncated symbols without guard intervals, and the receiver reconstructs the full symbol structure with zeros, achieving the same protective function in reverse.
2Productivity
If zero-padding is inserted into CP interval to increase transmission rate, then productivity is improved, but truncated intervals remain as guard intervals and transmission time cannot be shortened
Solution Approach 1:
The patent completely removes the guard interval portion from transmission, unlike zero-padding schemes that retain the CP structure. By extracting and eliminating the CP entirely and replacing it with direct data transmission followed by receiver-side zero-insertion, the system achieves both higher transmission rate and shorter transmission time.
3Productivity
If OFDM symbols are truncated and concatenated without guard intervals to improve temporal efficiency, then productivity is improved, but inter-carrier interference occurs
Solution Approach 1:
The patent introduces zero-padding as an intermediary element that the receiver inserts to maintain orthogonality between subcarriers. This intermediary restores the protective function against ICI that would otherwise be lost due to truncation, allowing the system to benefit from time efficiency while mitigating the harmful interference effect.
Solution Approach 2:
The patent changes the parameter of symbol structure from conventional CP-OFDM to truncated OFDM with receiver-side zero-insertion. By modifying how orthogonality is maintained (from transmitter-side guard intervals to receiver-side zero-padding), the system achieves better temporal efficiency while controlling ICI through parameter transformation rather than structural retention.
Data Source
AI summary
Provided is a transmission device that is compatible with conventional schemes and can improve transmission efficiency. A transmission device of an orthogonal frequency division multiplexing scheme, includes: a redundant signal addition circuit that adds a redundant signal of a predetermined number of sampling points to multiple sampling points of an output of an IFFT circuit or an IDFT circuit; and a sampling point truncation circuit that truncates a predetermined number of sampling points from each of a front end and a rear end of an output of the redundant signal addition circuit. An output symbol of the sampling point truncation circuit is transmitted.