OFDM Transmission Apparatus Sub-Carrier Power Control
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Solution Overview
Problem
In wireless communication systems using OFDMA, the varying number of transmission sub-carriers allocated to terminal apparatuses leads to fluctuations in transmission power and noise floors, causing interference and reduced signal-to-noise ratios when different terminal apparatuses transmit simultaneously.
Innovation Solution
A transmission apparatus is designed with a multiplier and an inverse fast Fourier transformer, along with a multiplication-coefficient output circuit that adjusts the signal amplitude based on the number of transmission sub-carriers, maintaining constant amplitude and reducing noise interference across different sub-carrier allocations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of transmission sub-carriers is varied to allocate resources dynamically, then the adaptability of the system is improved, but the transmission power and noise floor fluctuate causing interference
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the multiplication coefficient based on the number of transmission sub-carriers. When the number of sub-carriers changes, the system calculates a corresponding multiplication coefficient and applies it to the signal to maintain constant transmission power and noise floor, thereby resolving the contradiction between flexible sub-carrier allocation and stable transmission parameters
2Adaptability or versatility
If dynamic sub-carrier allocation is implemented, then the system can adapt to different transmission requirements, but the noise floor becomes unstable affecting signal quality
Solution Approach 1:
The patent implements feedback by monitoring the number of transmission sub-carriers and using this information to adjust the multiplication coefficient. This closed-loop control ensures that the noise floor remains stable despite changes in sub-carrier allocation, as the system continuously adapts the signal parameters based on actual transmission conditions
Data Source
AI summary
A transmission apparatus includes: a multiplier configured to multiply a signal provided on a complex plane by a multiplication coefficient corresponding to a number of transmission sub-carriers; and an inverse fast Fourier transformer configured to perform an inverse fast Fourier transform on the multiplied signal.