5G Reference Signal Mapping for Hybrid Waveforms
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Solution Overview
Problem
The hybrid-waveform scenario in 5G wireless communications, combining OFDM and DFT-s-OFDM, poses challenges in DMRS transmission and reception, requiring a solution that maintains low PAPR characteristics and supports multi-user MIMO transmission while ensuring spectral efficiency and resource scheduling flexibility.
Innovation Solution
A method and device for transmitting reference signals using a resource mapping pattern that maps DFT-s-OFDM waveforms in a comb-shaped manner in the frequency domain and OFDM waveforms to resources not used by DFT-s-OFDM, allowing for orthogonalization of multiple antenna ports and reducing system complexity and overheads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LTE uplink DMRS is consecutively mapped in frequency domain to maintain low-PAPR characteristic, then low-PAPR characteristic is preserved, but resource scheduling flexibility is lowered and cell throughput is decreased
Solution Approach 1:
The patent segments the frequency domain resources by introducing non-consecutive mapping patterns for DMRS, dividing the previously continuous frequency resources into separated segments. This allows data to be multiplexed in the gaps between DMRS symbols, thereby improving resource utilization and scheduling flexibility while maintaining the low-PAPR characteristic through careful selection of mapping patterns.
Solution Approach 2:
The patent introduces time-domain discrete mapping as an additional dimension alongside frequency-domain mapping. By mapping DMRS discretely in both time and frequency domains, the system achieves more flexible resource allocation and enables multi-user MIMO transmission, thereby improving cell throughput and scheduling flexibility without compromising the low-PAPR characteristic.
2Productivity
If LTE downlink DMRS is discretely mapped in time domain and frequency domain to multiplex data and DMRS, then spectral efficiency is improved, but low-PAPR characteristic is destroyed making it inapplicable to DFT-s-OFDM waveform
Solution Approach 1:
The patent applies different mapping strategies to different waveforms: for OFDM waveform, discrete mapping in time and frequency domains is used to maximize spectral efficiency; for DFT-s-OFDM waveform, frequency-domain comb-shaped mapping is used to preserve low-PAPR characteristic. This local adaptation to different waveform requirements resolves the contradiction between spectral efficiency and low-PAPR characteristic.
Solution Approach 2:
The patent changes the mapping parameters (time-domain discreteness, frequency-domain distribution) based on the selected waveform type. By dynamically adjusting these parameters, the system achieves optimal spectral efficiency for OFDM while maintaining low-PAPR for DFT-s-OFDM, enabling hybrid-waveform support in 5G uplink.
3Adaptability or versatility
If hybrid-waveform scenario combines OFDM and DFT-s-OFDM, then system capacity and coverage are improved, but DMRS transmission complexity increases and waveform-specific requirements conflict
Solution Approach 1:
The patent designs a universal DMRS mapping framework that can accommodate both OFDM and DFT-s-OFDM waveforms. By defining antenna port-specific mapping patterns that work for both waveforms, the system reduces transmission complexity and avoids waveform-specific configurations, thereby resolving the conflict between adaptability and complexity.
Solution Approach 2:
The patent introduces dynamic waveform selection and corresponding adaptive DMRS mapping. The system can dynamically switch between OFDM and DFT-s-OFDM waveforms based on channel conditions and user requirements, with each waveform having its optimized mapping pattern. This dynamic adaptation reduces overall system complexity by providing clear, waveform-specific rules rather than attempting a single complex solution for all cases.
Data Source
AI summary
Embodiments of this application provide a method for transmitting a reference signal, including: sending, by a network device to UE, information about a waveform, an antenna port, and a resource block, where the waveform includes an OFDM waveform or a DFT-s-OFDM waveform, the antenna port indicates a resource mapping pattern used by the UE to send or receive a reference signal, and in a symbol of the resource mapping pattern, a reference signal corresponding to the DFT-s-OFDM waveform is mapped in frequency domain in a comb-shaped manner, and a reference signal corresponding to the OFDM waveform is mapped to a frequency domain resource to which the DFT-s-OFDM waveform is not mapped; and sending, by the network device, the reference signal or receiving the reference signal on the resource block based on the information about the waveform, the information about the antenna port, and the information about the resource block.