CP-OFDM Signal Decoding Using Maximal Ratio Combining
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Orthogonal frequency-division multiplexing (OFDM) systems with cyclic-prefix (CP) guard intervals suffer from signal energy efficiency loss due to the discarding of energy in the CP guard interval, which is presumed to be affected by inter-symbol interference, resulting in only 80% of the transmitted signal energy being usable for data decoding.
Innovation Solution
A method that involves determining two data sets from different time windows of a CP-OFDM signal data block, where the second data set includes repeated-data not present in the first data set, and combining these sets through time-alignment and maximal ratio combining (MRC) to increase the signal-to-noise ratio by utilizing the non-correlated noise in the CP guard interval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the CP guard interval is used to reduce inter-symbol interference, then signal reliability is improved, but signal energy efficiency deteriorates due to discarding the repeated data energy
Solution Approach 1:
The patent recovers the signal energy that was previously discarded in the CP guard interval by extracting and combining the repeated data portions with the main data, transforming waste energy into useful signal energy to improve overall energy efficiency
Solution Approach 2:
The patent converts the harmful effect of discarding CP energy into a benefit by utilizing the repeated data in the CP interval for signal combining, where the previously wasted energy becomes a source of additional signal strength and diversity
2Reliability
If the CP-OFDM signal repeats symbol data in the guard interval, then inter-symbol interference is reduced, but the transmission time increases due to the additional guard interval
Solution Approach 1:
The patent makes the CP guard interval serve multiple functions: it continues to protect against inter-symbol interference while simultaneously providing redundant data for signal combining and energy recovery, maximizing the utility of the guard interval
3Device complexity
If the receiver discards the CP guard interval data, then processing complexity is reduced, but signal-to-noise ratio deteriorates due to loss of signal energy
Solution Approach 1:
The patent applies partial processing to the CP interval by extracting only the repeated data portions for combining, rather than processing the entire CP interval, thus balancing the trade-off between processing complexity and signal-to-noise ratio improvement
Data Source
AI summary
A method to decode an orthogonal frequency-division multiplex (OFDM) signal data block that includes symbol-data in a data interval, repeated-data in a cyclic-prefix (CP) guard interval, and noise. The signal is often called a CP-OFDM signal. The method includes determining a first data set based on data samples taken during a first time window of a data block. The method also includes determining a second data set based on data samples taken during a second time window of the data block, wherein the second time window is selected so that the second data set includes repeated-data not present in the first data set. The method also includes combining the first data set and the second data set in a manner effective to increase a signal-to-noise ratio of the signal. The combining process increases signal data energy more than noise data energy.