Waveform Indication for High-Frequency 5G Link Budget
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Solution Overview
Problem
Current 5G New Radio (NR) standards are limited to OFDM for downlink and SC-FDM/OFDM for uplink in high-frequency bands, which may not optimize link budget and complexity, and there is a need for flexible waveform support to improve transmission efficiency and coverage in unlicensed/shared spectrum above 52.6 GHz.
Innovation Solution
The method involves indicating multiple waveforms, such as SC-QAM and SC-FDM, for both downlink and uplink transmissions using synchronization signal blocks, primary and secondary synchronization signals, and physical broadcast channels, allowing for flexible waveform selection and mixed waveform scenarios to enhance link budget and reduce complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If OFDM waveform is used for high-frequency transmissions above 60 GHz, then transmission capability is maintained, but peak-to-average power ratio increases affecting link budget and coverage area
Solution Approach 1:
The system dynamically selects between OFDM and single-carrier waveforms based on frequency band and service requirements. For frequencies above 60 GHz, single-carrier waveforms are preferred to reduce PAPR and improve link budget, while OFDM can be used in other scenarios. This dynamic adaptation resolves the contradiction by allowing the system to optimize for link budget when needed while maintaining the option for other waveforms when appropriate.
Solution Approach 2:
The patent changes the waveform parameter from fixed OFDM to variable waveform types (OFDM, DFT-S-OFDM, SC-QAM) based on frequency band and service requirements. This parameter change enables the system to achieve lower PAPR in high-frequency bands above 60 GHz, directly improving link budget while maintaining transmission capability.
2Productivity
If multiple waveform types are supported for frequencies above 60 GHz, then transmission efficiency and coverage are improved, but system complexity increases
Solution Approach 1:
The system is designed with multi-functionality to support multiple waveform types (OFDM, DFT-S-OFDM, SC-QAM) within a unified framework. The base station and user equipment can adaptively select the appropriate waveform based on frequency band, service type, and channel conditions. This universality allows the system to achieve high transmission efficiency across different scenarios while managing complexity through standardized procedures for waveform indication and selection.
Solution Approach 2:
The base station performs preliminary waveform indication through synchronization signal blocks and system information before actual data transmission. This allows user equipment to prepare the appropriate waveform processing in advance, reducing real-time complexity while enabling flexible waveform selection for optimal transmission efficiency in high-frequency bands.
3Reliability
If single-carrier waveforms are used for downlink transmissions in high-frequency bands, then peak-to-average power ratio is reduced improving link budget, but waveform flexibility is limited
Solution Approach 1:
The system dynamically adapts waveform selection based on frequency band and service requirements. For downlink transmissions above 60 GHz, single-carrier waveforms are preferred to reduce PAPR and improve link budget. However, the system maintains flexibility by allowing switching to other waveform types when service requirements or channel conditions dictate, resolving the contradiction between link budget optimization and waveform flexibility.
Solution Approach 2:
The waveform parameter is changed from fixed to variable, allowing the system to select single-carrier waveforms when link budget is the priority (high-frequency bands) while maintaining the capability to use other waveforms when adaptability is needed. This parameter flexibility resolves the contradiction by enabling context-dependent waveform selection.
Data Source
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Figure 3A~3D
AI summary
There is a large chunk of unlicensed/shared high-frequency spectrum above the 5G radio frequency that begin to be utilized for 5G applications. 5G currently supports a limited number of waveforms. The other waveforms may be beneficial to the shared high-frequency bands, such as SC-QAM/SC-FDM for downlink transmission and SC-QAM for uplink transmission to improve link budget and to reduce complexity. A method, apparatus, and computer-readable medium at a user equipment (UE) are disclosed to determine a first waveform for a broadcast channel, based in part on a received synchronization block signal from a base station. Then the UE further determines a second waveform for at least one signaling channel, based in part on the received broadcast channel.