Per-tone Power Control in OFDM Sub-carriers
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Solution Overview
Problem
MIMO systems face limitations in performance due to high costs and complexity from requiring multiple antennas, and existing beamforming techniques are incompatible with single-antenna systems, with performance also being limited by the number of antennas.
Innovation Solution
A method for calculating channel state information (CSI) to determine signal attenuation levels across sub-carrier frequencies, allowing for power compensation by increasing power on sub-carriers with greater attenuation and decreasing power on those with lesser attenuation, enabling improved signal transmission without the need for multiple antennas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MIMO systems use multiple antennas to improve performance, then spectral efficiency and link reliability increase, but device complexity and cost increase
Solution Approach 1:
The patent changes the parameter of signal power distribution across sub-carriers based on channel state information. By adjusting power levels dynamically for each sub-carrier frequency, the system achieves improved link reliability without adding multiple antennas, thus avoiding increased device complexity
Solution Approach 2:
The patent segments the overall signal into multiple sub-carrier frequencies and applies different power control to each segment. This per-sub-carrier power control allows targeted optimization of signal transmission on frequencies with better channel conditions, improving reliability without requiring multiple physical antennas
2Productivity
If beamforming techniques are used to improve signal transmission, then throughput increases, but compatibility with single-antenna systems decreases
Solution Approach 1:
The patent implements a power control mechanism that functions universally across different antenna configurations. The same per-sub-carrier power control algorithm can be applied whether the system has one antenna or multiple antennas, making it compatible with both single-antenna and MIMO systems while improving throughput
3Device complexity
If equal power is distributed across all sub-carriers, then system simplicity is maintained, but transmission performance deteriorates due to frequency selective fading
Solution Approach 1:
The patent applies local quality by assigning different power levels to different sub-carrier frequencies based on their individual channel conditions. Sub-carriers experiencing less fading receive higher power allocation, while those with severe fading receive lower power, optimizing transmission performance locally for each frequency band
Data Source
AI summary
A first communication device calculates channel state information (CSI), and based on the CSI, (i) determines a first signal attenuation level corresponding to signals transmitted over a first sub-carrier frequency signal, and (ii) determines a second signal attenuation level corresponding to signals transmitted over a second sub-carrier frequency signal. The first communication device transmits data encoded over the first sub-carrier frequency and the second and second sub-carrier frequency to a second communication device by (i) increasing power loaded to signals transmitted over a sub-carrier frequency from among the first sub-carrier frequency and the second sub-carrier frequency that is associated with greater signal attenuation, and (ii) decreasing power loaded to signals transmitted over a sub-carrier frequency from among the first sub-carrier frequency and the second sub-carrier frequency that is associated with lesser signal attenuation.