Dynamic Downlink Waveform Switching for PAPR and Bandwidth Trade-offs
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Solution Overview
Problem
Current wireless communication systems, particularly those using OFDMA waveforms, face challenges in providing optimal broadband access and user experience due to high peak-to-average power ratio (PAPR) transmissions, which limit transmit power and are less effective in scenarios with low geometry wireless nodes experiencing high path loss and diminished signal quality.
Innovation Solution
The system dynamically switches between multiple carrier (MC) and single carrier (SC) waveforms based on downlink geometry and channel conditions, using radio resource control (RRC) and downlink control information (DCI) to select the appropriate waveform for improved performance, especially in millimeter wave (mmW) frequency ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If OFDMA waveforms are used for downlink communication, then bandwidth efficiency and multiplexing capability are improved, but peak-to-average power ratio increases and transmit power is limited
Solution Approach 1:
The system dynamically switches between OFDMA and single-carrier waveforms based on channel conditions, UE location, and quality of service requirements. This allows the system to adaptively select the optimal waveform characteristic (high bandwidth efficiency or high transmit power) for each specific communication scenario, resolving the contradiction between bandwidth efficiency and transmit power.
2Productivity
If OFDMA waveforms are used to serve multiple UEs, then multiplexing capability is improved, but performance deteriorates for low geometry wireless nodes experiencing high path loss
Solution Approach 1:
The system applies different waveform characteristics to different user scenarios: OFDMA for median to high geometry UEs with good channel conditions, and single-carrier waveforms for low geometry UEs experiencing high path loss. This localized adaptation of waveform quality to specific user needs resolves the contradiction between multiplexing capability and signal quality for vulnerable nodes.
3Productivity
If high PAPR transmissions are used to increase bandwidth efficiency, then bandwidth utilization is improved, but transmit power amplifiers cannot operate at higher power
Solution Approach 1:
The system changes the waveform parameter (PAPR) based on communication requirements by switching between OFDMA and single-carrier modes. When high transmit power is needed, the system selects single-carrier waveforms with low PAPR, allowing power amplifiers to operate efficiently. When bandwidth efficiency is the priority and channel conditions permit, OFDMA with high PAPR is used. This dynamic parameter adjustment resolves the contradiction between bandwidth efficiency and transmit power amplifier operation.
Data Source
AI summary
Systems and methods providing for dynamic switching between the various waveforms on the downlink are described. Embodiments of a dynamic downlink waveform switching implementation may, for example, support utilization of one or more multiple carrier (MC) waveform (e.g., OFDMA) or other high peak to average power ratio (PAPR) waveform and one or more SC (SC) waveform (e.g., discrete Fourier transform-spread-orthogonal frequency division multiplexing (DFT-S-OFDM)) or other low PAPR waveform. Dynamic selection of a downlink waveform may be made by an access point based upon various metrics, including relative distance to a served an access terminal and the preference of downlink waveform indicated by a served an access terminal. A downlink waveform selection indication may be signaled from the access point to the served an access terminal using downlink control information (DCI).