FDM Waveform Scheduling for PAPR Control in 5G
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Solution Overview
Problem
In wireless communication systems, particularly in 5G New Radio (NR) standards, the peak-to-average power ratio (PAPR) of high-frequency transmissions increases when frequency division multiplexing (FDM) multiple low-PAPR waveforms through the same power amplifier, leading to potential PA saturation and distortion, which affects signal reception at the cell edge.
Innovation Solution
Implementing new scheduling modes that restrict the range of parameters known to increase PAPR for FDM transmissions, such as limiting the rank, modulation order, and bandwidth of waveforms, and employing finer minislot partitioning with shared reference signals to minimize PAPR during time-frequency resource allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If frequency division multiplexing (FDM) is used to transmit multiple low-PAPR waveforms through the same power amplifier, then spectral efficiency and resource utilization are improved, but the PAPR increases causing power amplifier saturation and distortion
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting modulation order, rank, and bandwidth parameters based on FDM transmission conditions. The gNB schedules waveforms with restricted parameter ranges that are known to increase PAPR, thereby maintaining lower PAPR while enabling FDM transmissions through the same power amplifier.
Solution Approach 2:
The patent implements dynamic scheduling modes that adapt waveform parameters in real-time based on channel conditions and FDM transmission requirements. The system dynamically selects between different scheduling modes (e.g., mode 1 with restricted parameters, mode 2 with finer minislot partitioning) to optimize the balance between spectral efficiency and PAPR control.
2Productivity
If multiple waveforms are frequency division multiplexed to increase transmission capacity, then system throughput is improved, but signal quality at cell edge deteriorates due to power amplifier saturation
Solution Approach 1:
The patent changes operational parameters by restricting modulation order and rank for FDM transmissions. By limiting these parameters to ranges that produce lower PAPR, the system prevents power amplifier saturation and maintains signal quality at the cell edge while still achieving improved system throughput through FDM.
Solution Approach 2:
The system implements feedback mechanisms where the gNB monitors PAPR levels and signal quality metrics, then adjusts scheduling decisions accordingly. When FDM transmissions cause PAPR to exceed thresholds or degrade cell edge performance, the scheduler modifies parameter selections to restore acceptable signal quality while maintaining throughput.
3Device complexity
If conventional scheduling modes are used for FDM transmissions, then implementation complexity is reduced, but PAPR control capability is insufficient leading to distortion
Solution Approach 1:
The patent segments the scheduling space into distinct modes with predefined parameter restrictions. By dividing the complex scheduling problem into manageable modes (e.g., mode 1 for restricted parameters, mode 2 for fine-grained minislot control), the system achieves effective PAPR control without overwhelming implementation complexity.
Solution Approach 2:
The patent applies preliminary action by pre-defining restricted parameter ranges and scheduling modes before FDM transmissions occur. The gNB is configured with advance knowledge of which parameter combinations produce acceptable PAPR levels, allowing it to make rapid scheduling decisions without real-time PAPR optimization complexity.
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AI summary
A method of wireless communication is disclosed, which comprises: receiving frequency division multiplexed, FDM, symbols in a receiver, wherein the FDM symbols are scheduled by a transmitter based on one or more waveform parameters during a time interval over which the FDM symbols are transmitted by the transmitter; and decoding the FDM symbols in the receiver based on application of the one or more waveform parameters.