Selective Crest Factor Reduction and Digital Pre-Distortion in Wireless Transmitters
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Solution Overview
Problem
The high peak-to-average power ratio (PAPR) in OFDM systems for wireless communication leads to distortion issues in power amplifiers, causing out-of-band emissions and spectral regrowth, which can result in increased bit-error-rate and non-linear amplifier output, necessitating reduced power output and inefficient operation.
Innovation Solution
Implementing selective crest factor reduction (CFR) and digital pre-distortion (DPD) techniques based on transmission bandwidth, where CFR reduces signal peaks and DPD linearizes power amplifiers by applying inverse distortion, allowing for higher efficiency and linearity at the amplifier output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If crest factor reduction and digital pre-distortion are applied to reduce PAPR, then amplifier linearity and efficiency improve, but device complexity increases
Solution Approach 1:
The system dynamically adjusts the application of CFR and DPD based on real-time bandwidth conditions. When bandwidth is below the threshold, CFR and DPD are enabled to improve linearity; when bandwidth exceeds the threshold, they are disabled to reduce complexity. This dynamic adaptation resolves the contradiction by making the system flexible rather than static.
Solution Approach 2:
The invention changes the operational parameters of CFR and DPD based on bandwidth conditions. By monitoring the bandwidth parameter and adjusting whether these techniques are applied, the system optimizes the trade-off between linearity improvement and complexity increase, applying these techniques only when beneficial.
2Productivity
If selective CFR and DPD are applied based on bandwidth threshold, then transmitter efficiency improves, but measurement and control difficulty increases
Solution Approach 1:
The system performs self-monitoring of bandwidth conditions and automatically makes decisions about applying CFR and DPD without requiring external control. The transmitter itself detects when bandwidth exceeds the threshold and autonomously adjusts its operation, simplifying the overall control architecture while maintaining efficiency.
Data Source
AI summary
A method for wireless communication includes allocating a transmission bandwidth for transmission to a user equipment (UE). The method further includes determining if the allocated transmission bandwidth is less than or equal to a maximum estimated BWDPD. The maximum estimated BWDPD is the maximum estimated signal bandwidth that a transmitter is configured to digitally pre-distort. The method also includes digitally pre-distorting transmit signals and transmitting the digitally pre-distorted transmit signals to the UE if the allocated transmission bandwidth is less than or equal to the maximum estimated BWDPD. The method also includes transmitting to the UE without digitally pre-distorting the signals if the allocated transmission bandwidth is not less than or equal to the maximum estimated BWDPD. The method also includes applying digital crest factor reduction to the transmit signals if the allocated transmission bandwidth is less than or equal to the maximum estimated BWCFR.