Common Comb Reference Signals for Unified OFDM and DFTS-OFDM
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Solution Overview
Problem
The differing transmission schemes for DL and UL in LTE, specifically the use of OFDM and DFTS-OFDM, lead to issues in reference signal design, particularly in the context of 5G NR, which complicates channel estimation and implementation due to the use of different FDM technologies.
Innovation Solution
A common comb-based reference signal structure is proposed for both OFDM and DFTS-OFDM in the uplink, allowing for unified handling and simplifying switching between these modes, with resource elements not used for reference signals in DFTS-OFDM being left empty to maintain low PAPR/CM, while in OFDM, these elements can be used for data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different reference signal structures are used for OFDM and DFTS-OFDM, then each transmission scheme can be optimized for its specific characteristics, but the system complexity increases and switching between modes becomes difficult
Solution Approach 1:
The patent applies universality by designing a common reference signal structure that works for both OFDM and DFTS-OFDM transmission schemes. The reference signal is defined with comb structure parameters (comb factor, offset, density) that can be configured to support multiple transmission modes without requiring separate reference signal designs, thereby reducing system complexity while maintaining optimization capabilities.
2Productivity
If different FDM technologies are used for UL transmissions, then transmission performance can be optimized for different scenarios, but channel estimation becomes more complex
Solution Approach 1:
The patent applies homogeneity by ensuring that the reference signal structure maintains consistent characteristics across different FDM technologies. By using a unified comb-based reference signal design with configurable parameters, the channel estimation process becomes standardized and simpler, as the same estimation algorithms can be applied regardless of whether OFDM or DFTS-OFDM is used for the data transmission.
3Productivity
If resource elements are used for data transmission in OFDM, then spectral efficiency increases, but PAPR increases requiring power backoff
Solution Approach 1:
The patent applies local quality by allowing different resource element configurations for different transmission modes. For OFDM, resource elements can be allocated for data transmission to achieve high spectral efficiency, while for DFTS-OFDM, the reference signal configuration can be adjusted to maintain low PAPR. The comb structure parameters enable localized optimization for each transmission scheme's specific requirements.
Data Source
AI summary
The present disclosure pertains to a terminal for a Radio Access Network, the terminal being adapted for transmission based on a first frequency division multiple access (FDMA) technology and for transmission based on a second frequency division multiple access technology. The terminal is adapted for transmitting reference signaling having a comb structure for transmission based on either the first FDMA technology or the second FDMA technology. The disclosure also pertains to related devices and methods.