Uplink Terminal Waveform Switching for Coverage and Resource Efficiency
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Solution Overview
Problem
Current 5G NR systems lack an efficient method for switching between OFDM and DFT-s-OFDM signal waveforms in uplink transmission, particularly for terminals with varying maximum transmission power, which affects coverage and flexibility in different communication environments.
Innovation Solution
A terminal and communication method that efficiently switch between OFDM and DFT-s-OFDM by limiting the number of resource blocks allocated for DFT-s-OFDM, allowing proper waveform determination based on the number of allocated resource blocks, thereby maintaining coverage and simplifying design commonality between downlink and uplink transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If DFT-s-OFDM is used for uplink transmission, then coverage is improved due to lower PAPR and higher power efficiency, but the number of supported resource blocks is limited
Solution Approach 1:
The patent applies dynamics by making the waveform selection adaptive rather than static. The terminal dynamically switches between DFT-s-OFDM and CP-OFDM based on real-time conditions including the number of allocated resource blocks, maximum transmission power capability, and coverage requirements. This dynamic adaptation resolves the contradiction by allowing the system to use DFT-s-OFDM's low PAPR benefit when resource blocks are limited while transitioning to CP-OFDM when more resource blocks are allocated, thus optimizing both coverage and resource utilization.
Solution Approach 2:
The patent changes the parameter of waveform type based on the number of resource blocks and transmission power. When the number of resource blocks is below a threshold or when high transmission power is required, DFT-s-OFDM is selected to improve coverage. When resource blocks exceed the threshold, CP-OFDM is selected to support larger bandwidth allocations. This parameter-based selection mechanism resolves the contradiction between coverage improvement and resource block limitation.
2Adaptability or versatility
If OFDM is used for uplink transmission, then resource allocation flexibility is improved, but PAPR increases reducing power efficiency
Solution Approach 1:
The system dynamically selects between CP-OFDM and DFT-s-OFDM based on allocation size and power requirements. For small resource block allocations where power efficiency is critical, DFT-s-OFDM is chosen. For larger allocations where flexibility is more important, CP-OFDM is selected. This dynamic waveform selection resolves the contradiction by matching the waveform characteristics to the specific allocation scenario.
Solution Approach 2:
The patent changes the waveform parameter based on the resource block allocation size. When resource blocks are few, DFT-s-OFDM provides better power efficiency. When resource blocks increase, CP-OFDM provides better flexibility for resource allocation. The threshold-based parameter change resolves the contradiction between power efficiency and resource allocation flexibility.
3Adaptability or versatility
If waveform switching between OFDM and DFT-s-OFDM is implemented, then adaptability to different use cases is improved, but system complexity increases
Solution Approach 1:
The patent simplifies waveform switching by establishing clear parameter thresholds. The terminal compares the number of allocated resource blocks against a predetermined threshold and selects the waveform accordingly. This threshold-based parameter change approach provides adaptability to different use cases while avoiding complex decision-making algorithms, thus resolving the contradiction between adaptability and system complexity.
Solution Approach 2:
The patent segments the uplink transmission scenarios into distinct regions based on resource block allocation size. One segment uses DFT-s-OFDM for small allocations, another uses CP-OFDM for large allocations. This segmentation simplifies the waveform selection process by creating clear boundaries between different waveform usage scenarios, reducing the complexity of waveform switching while maintaining adaptability.
4Use of energy by moving object
If DFT-s-OFDM is used for uplink, then amplifier power efficiency is improved, but signal waveform generation complexity increases compared to simple OFDM
Solution Approach 1:
The system dynamically selects DFT-s-OFDM only when the benefits of amplifier power efficiency outweigh the additional waveform generation complexity. By making waveform selection adaptive based on resource block allocation and power requirements, the system optimizes the trade-off between power efficiency and generation complexity, using DFT-s-OFDM's advanced generation only when necessary for power-critical scenarios.
Solution Approach 2:
The patent changes the waveform parameter to DFT-s-OFDM when power efficiency is the priority (small resource block allocations). The additional complexity of DFT-based spreading is accepted only when it provides meaningful power efficiency improvements. When resource blocks are abundant, the system reverts to simpler CP-OFDM, thus managing the complexity-power efficiency trade-off through parameter-based selection.
Data Source
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AI summary
In a terminal (200), a Pre-IFFT unit (204) generates a signal waveform for multicarrier transmission (OFDM) or single carrier transmission (DFT-s-OFDM) in uplink. A transmitter (208) transmits a signal with the generated signal waveform using a resource block (PRB) allocated to the terminal (200). In this process, a restriction is imposed on the number of resource blocks for which the Pre-IFFT unit (204) is allowed to generate the signal waveform for the single carrier transmission. Thus, it is possible to efficiently switch between OFDM and DFT-s-OFDM in the signal waveform generation.