Autocorrelation Switch Notifier for OFDM Parameter Adaptation
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Solution Overview
Problem
In OFDM wireless communication, adaptive modulation changes in communication parameters lead to inaccurate notification and increased processing time due to channel fading, causing difficulties in equalization and demodulation.
Innovation Solution
A communication apparatus that includes a changer for modifying communication parameters based on channel characteristics, a selector for choosing switch data sequences with specific autocorrelation properties, and a switch notifier to generate and transmit transmission frames, ensuring accurate notification of parameter changes using autocorrelation functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If adaptive modulation is performed to improve transmission efficiency by changing communication parameters, then transmission efficiency is improved, but the accuracy of notifying parameter changes deteriorates due to channel fading
Solution Approach 1:
The patent applies preliminary action by pre-processing the notification signal through specific signal processing techniques before transmission. The notification signal is processed to enhance its robustness against channel fading, ensuring that parameter change information can be reliably detected even in degraded channel conditions. This pre-processing step occurs before the actual adaptive modulation takes place, preparing the notification mechanism in advance.
Solution Approach 2:
The patent introduces an intermediary mechanism in the form of a dedicated notification signal processing path. This intermediary process handles the encoding and transmission of parameter change notifications separately from the data transmission, using specific signal processing techniques that make the notification independent of the data signal's susceptibility to fading. This intermediary layer protects the control information from the harmful effects of channel conditions.
2Productivity
If adaptive modulation changes communication parameters to adapt to channel conditions, then transmission efficiency is improved, but processing time increases due to additional equalization requirements
Solution Approach 1:
The patent extracts the notification signal processing from the main data processing flow. By separating the parameter change notification into a distinct, pre-processed signal path, the system eliminates the need for the receiving end to perform time-consuming equalization on the notification signal itself. The notification is extracted as a separate entity that can be processed more efficiently, reducing overall processing time while maintaining adaptive modulation benefits.
Solution Approach 2:
The patent applies preliminary action by pre-processing the notification signal to make it inherently more robust and easier to detect. This pre-processing reduces the computational burden during actual reception and demodulation, as the notification signal requires less complex equalization and detection algorithms compared to raw adaptive modulation signals. The time-consuming equalization work is reduced through this preliminary preparation.
3Adaptability or versatility
If notification signals are transmitted through fading channels, then parameter changes can be communicated, but the reliability of detection deteriorates
Solution Approach 1:
The patent introduces an intermediary notification signal that acts as a mediator between the adaptive modulation control and the receiving end detection. This intermediary signal is specifically processed to enhance its detectability in fading channels, using techniques that make it distinct from and more robust than ordinary data signals. The intermediary layer protects the control information transmission from channel degradation.
Solution Approach 2:
The patent applies preliminary action by pre-processing the notification signal with specific encoding and modulation techniques that enhance its robustness before transmission. This pre-processing ensures that the notification signal maintains its integrity better than unprocessed signals would in fading conditions, improving detection reliability without requiring additional retransmissions or complex error correction during reception.
Data Source
AI summary
When a changer changes a communication parameter based on a channel characteristic, a selector selects a switch data sequence corresponding to the changed communication parameter. A serial-parallel converter performs a serial-parallel conversion on a switch data sequence. An IFFT unit performs an IFFT. A transmitter synthesizes a calculation result from the IFFT unit to generate data symbol, and generates a transmission frame based on the data symbol. The transmitter then transmits the transmission frame to a second apparatus. A receiver receives a transmission frame from the second apparatus to generate data symbol. An FFT unit performs an FFT on the data symbol to generate a parallel signal. If a correlator determines that a notification of the change in the communication parameter has been correctly transmitted based on an autocorrelation analysis of the parallel signal, a communication apparatus starts communication using the changed communication parameter.