Open-Loop Power Controller for OFDMA Terminals
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Solution Overview
Problem
In OFDMA communication systems, terminals outside the full loading range (FLR) face challenges with open-loop power control due to limited transmission power, leading to ineffective initial ranging operations as the power amplifier cannot compensate for increased path loss, and initial ranging signals have low strength.
Innovation Solution
A terminal with a power amplifier, open-loop power controller, and gain controller that measures received signal strength to adjust the power concentration gain, allowing the terminal to increase amplifier gain and apply a power concentration gain when necessary to enhance transmission power, enabling normal initial ranging operations outside the FLR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the terminal transmits using one subchannel to all subchannels in OFDMA system, then the full loading range (FLR) distance is extended, but the transmission power must be kept low to avoid interference at cell boundaries
Solution Approach 1:
The patent implements dynamic gain control of the power amplifier based on received signal strength measurements. The open-loop power controller continuously monitors the downlink signal quality and adjusts the uplink transmission gain accordingly, allowing the terminal to adaptively increase power when needed while maintaining low power during good conditions, thus extending FLR without causing cell boundary interference
Solution Approach 2:
The system employs feedback mechanisms where the terminal measures received signal strength from the base station and uses this information to control its own transmission power. The open-loop power controller receives signal quality feedback and adjusts the power amplifier gain to maintain optimal transmission levels, enabling extended coverage while preventing interference
2Length of stationary object
If the terminal increases power amplifier gain to compensate for path loss, then the transmission distance is extended, but the terminal outside FLR cannot perform open-loop power control operation
Solution Approach 1:
The patent applies preliminary action by pre-configuring the power amplifier with an extended maximum gain setting that exceeds the normal FLR limit. This allows terminals outside the conventional FLR to initially transmit with sufficient power to establish connection, after which normal power control operations take over to maintain optimal transmission levels
3Use of energy by moving object
If the terminal transmits initial ranging signal with low power, then energy consumption is reduced, but the initial ranging operation cannot be performed successfully
Solution Approach 1:
The system dynamically adjusts transmission power based on the ranging operation status. During initial ranging, the terminal temporarily increases power amplifier gain to ensure the ranging signal is detected successfully. Once connected, the system transitions to normal dynamic power control that balances energy consumption with reliable communication, allowing the terminal to reduce power when the ranging phase is complete
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables the terminal to perform open-loop power control and maintain effective initial ranging operations even outside the FLR by maximizing the power amplifier's gain, ensuring reliable communication.
Implementation Method 1
a power amplifier, configured to amplify the transmission signal by controlling a gain to increase transmission power
Implementation Method 2
an open-loop power controller, configured to measure a received signal strength to control the transmission power
Data Source
AI summary
A terminal of a communication system includes a power amplifier, an open-loop power controller, a gain controller, a modulator, and a digital/analog converter. The power amplifier amplifies transmission power of a transmission signal. The open-loop power controller measures a received signal strength to control the transmission power, and increases a gain of the power amplifier according to the received signal strength. The gain controller sets a power concentration gain and applies the power concentration gain to the transmission signal when the gain of the power amplifier is maximized. The modulator modulates the transmission signal. The digital/analog converter converts an input signal to an analog signal. The gain controller applies the power concentration gain to the trans mission signal modulated by the modulator, and transmits the power concentration gain to the digital/analog converter.