Uplink Reference Signal Discrete Mapping for 5G Waveform Flexibility
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Solution Overview
Problem
In 5G radio communication systems, there is a need for a mechanism to appropriately control the resource position for uplink reference signals, especially when using orthogonal frequency-division multiplexing (OFDM) and Discrete Fourier Transform-Spread-OFDM (DFT-s-OFDM waveforms, as DFT-s-OFDM restricts UL reference signal transmission to only one continuous sub-carrier, and higher frequency bands require suitable configurations for beam forming.
Innovation Solution
User equipment creates and transmits uplink reference signals based on predetermined configurations that discretely map frequency resources in the frequency direction within a specific time domain, allowing for flexible SRS configurations such as whole RB range transmission, partial RB transmission, or transmission using multiple beams, ensuring compatibility with both OFDM and DFT-s-OFDM waveforms and supporting beam forming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If DFT-s-OFDM waveform is used, then PAPR is suppressed and coverage is improved, but UL reference signal transmission is restricted to only one continuous sub-carrier
Solution Approach 1:
The patent segments the UL reference signal transmission into multiple parts: it allows transmission on one continuous sub-carrier as required by DFT-s-OFDM, while also enabling discrete frequency resource mapping across multiple sub-carriers through configurable parameters. This segmentation resolves the contradiction by satisfying both the continuous sub-carrier requirement for PAPR suppression and the flexible resource allocation need for reference signal transmission.
Solution Approach 2:
The patent introduces dynamic configurability through parameters such as frequencyResourceAllocation, subcarrierSpacing, and referenceSignalConfiguration, which allow the system to adaptively switch between continuous and discrete frequency resource mapping modes. This dynamic approach enables the system to optimize between PAPR suppression and transmission flexibility based on current channel conditions and service requirements.
2Productivity
If OFDM waveform is used, then throughput and SN ratio are improved, but resource overhead increases due to less efficient reference signal transmission
Solution Approach 1:
The patent changes key parameters including frequencyResourceAllocation (RB allocation), subcarrierSpacing, and referenceSignalConfiguration to optimize the balance between throughput and resource overhead. By adjusting these parameters, the system can achieve efficient reference signal transmission that minimizes overhead while maintaining high data transmission speeds characteristic of OFDM waveform.
3Quantity of substance
If discrete frequency resource mapping is used for UL reference signal, then resource overhead is reduced and beam forming support is improved, but transmission flexibility is constrained
Solution Approach 1:
The patent creates a universal reference signal transmission mechanism that can function in multiple modes: continuous sub-carrier mapping for DFT-s-OFDM compatibility, discrete frequency resource mapping for overhead reduction and beam forming, and hybrid configurations. This multi-functionality resolves the contradiction by allowing the system to select the appropriate mapping mode based on specific transmission requirements while maintaining support for both waveforms.
Data Source
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AI summary
There is provided user equipment of a radio communication system including a base station and the user equipment. The user equipment includes a creation unit that creates an uplink reference signal in accordance with a predetermined uplink reference signal configuration that is reported from the base station, or a predetermined uplink reference signal configuration that is defined in a specification; and a transmission unit that transmits the created uplink reference signal. In the predetermined uplink reference configuration, frequency resources for transmitting the uplink reference signal are discretely mapped in a frequency direction in one symbol within a predetermined time domain.