Digital RoF OFDM Symbol Compression for Optical Bandwidth Efficiency
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Solution Overview
Problem
Conventional digital RoF transmission technologies experience a worsening compression rate when compressing multiple kinds of OFDM symbols, due to differing frequency components and signal properties, leading to inefficient use of optical bandwidth.
Innovation Solution
The optical communication system adjusts the lengths of OFDM symbols by separating a portion of the symbol sequence based on acquired OFDM symbol information, equalizing the lengths of all symbols to be compressed, and multiplexing them for efficient transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple kinds of OFDM symbols are compressed together, then transmission bandwidth is reduced, but compression rate deteriorates due to differing frequency components and signal properties
Solution Approach 1:
The patent segments the compression process by separating the first OFDM symbol from the second and subsequent OFDM symbols. The first OFDM symbol is compressed independently using one set of compression parameters, while the second and subsequent OFDM symbols are compressed separately using different compression parameters. This segmentation allows each symbol type to be compressed optimally according to its specific signal characteristics, preventing the degradation of compression rate that would occur if all symbols were compressed together with a single parameter set.
2Productivity
If compression parameters are optimized for one OFDM symbol type, then compression efficiency improves for that symbol type, but performance deteriorates for other OFDM symbol types with different frequency characteristics
Solution Approach 1:
The patent applies local quality by assigning different compression parameters to different OFDM symbol types. Specifically, the first OFDM symbol (which may have different frequency characteristics, such as containing pilot symbols or synchronization signals) is compressed using a first set of parameters optimized for its properties, while the second and subsequent OFDM symbols (which typically contain data) are compressed using a second set of parameters optimized for data symbols. This localized optimization ensures that each symbol type achieves the best possible compression efficiency without compromising the performance of other symbol types.
Data Source
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Figure 3(A)~3(C)
AI summary
An optical communication system includes a signal processing apparatus and a wireless apparatus between which functions of a base station are divided, wherein a periodic symbol sequence including a cyclic prefix appended to a signal of a predetermined size to which an IFFT (Inverse Fast Fourier Transform) has been applied is transmitted between the signal processing apparatus and the wireless apparatus by means of digital RoF (Radio over Fiber) transmission, the signal processing apparatus and the wireless apparatus each include a transmission unit and a reception unit, the transmission unit includes: a first separation unit that acquires symbol information relating to a starting position of the symbol sequence and lengths of symbols constituting the symbol sequence, and that equalizes the lengths of the symbols by separating a portion of the symbol sequence based on the acquired symbol information; and a compression unit that compresses symbols that are to be compressed from which the separated portion of the symbol sequence has been removed, and the reception unit includes an expansion unit that expands the compressed symbols and restores the symbols.