OFDM Transmitter Signal Processing for OOB Reduction
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Solution Overview
Problem
The discontinuity of OFDM symbols in the time domain leads to high out-of-band (OOB) energy, affecting the performance of wireless transmission systems by causing interference between different communication systems.
Innovation Solution
A signal processing method that adds zero power padding (ZP) to the tail end of OFDM symbols and uses symmetric time domain window function point multiplication to improve continuity between neighboring OFDM symbols, reducing OOB energy by aligning data points as prefixes or suffixes and ensuring the sum of point coefficients corresponds to a symmetric window function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If OFDM symbols are transmitted independently without continuity processing, then the transmission structure is simple and easy to implement, but the out-of-band energy becomes excessively high causing interference between different communication systems
Solution Approach 1:
The patent applies preliminary action by performing continuity processing on OFDM symbols before transmission. Specifically, it copies the last several samples of each OFDM symbol and appends them to the beginning of the next symbol, creating temporal overlap and continuity. This preprocessing step ensures smooth transitions between symbols, reducing spectral leakage and out-of-band energy before the signals are transmitted, thereby preventing interference with other communication systems.
2Object-generated harmful factors
If continuity processing is applied to OFDM symbols to reduce out-of-band energy, then interference between communication systems is reduced, but the processing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the continuity processing into distinct, manageable steps: (1) extracting the last N samples from each OFDM symbol, (2) storing these samples temporarily, and (3) appending them to the beginning of the next symbol. This segmented approach breaks down the complex continuity processing into simple, modular operations that can be efficiently implemented in existing OFDM transmitters with minimal additional hardware or software complexity.
Data Source
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AI summary
Embodiments of the present invention disclose a signal processing method and a transmitter. The method is applied to an OFDM wireless transmission system, the system includes at least two OFDM symbols, and the method includes: adding, by a transmitter, a zero power padding ZP to a tail end of each of the at least two OFDM symbols; adding, by the transmitter, data of Nw consecutive points at one end of a first OFDM symbol of the at least two OFDM symbols to the ZP at the other end of the first OFDM symbol, so that the data of the Nw points is used as a prefix and/or a suffix of the first OFDM symbol, where the first OFDM symbol includes data of N points, and N > Nw; and performing, by the transmitter, point multiplication processing with symmetric time domain window function on the data of the Nw points at the two ends of the first OFDM symbol to which the prefix and/or the suffix is added, so that a sum of point coefficients corresponding to the symmetric time domain window function is 1. This aims to improve continuity between neighboring OFDM symbols to reduce an OOB.