DFT-S-OFDM Multiplexing with Excess Bandwidth Shaping
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Solution Overview
Problem
Existing 5G-NR DFT-s-OFDM waveforms require at least one data symbol and one reference symbol, doubling latency and having a high RS overhead, which is not suitable for low latency and high-power efficiency required in 6G mobile communication systems.
Innovation Solution
A method involving time-multiplexing data and reference sequences to generate a filtered-extended bandwidth DFT-s-OFDM symbol, using spectrum shaping filters to reduce PAPR and enable one-shot transmission with flexible RS overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional DFT-s-OFDM uses separate data symbols and reference symbols, then channel estimation accuracy is improved, but transmission latency is doubled and RS overhead increases to 50%
Solution Approach 1:
The patent merges data and reference sequences into a single multiplexed sequence that is transformed by DFT, allowing both data transmission and channel estimation to occur within one OFDM symbol. This combining eliminates the need for separate data and reference symbols, reducing latency while maintaining channel estimation capability through the integrated structure.
Solution Approach 2:
The multiplexed sequence serves dual functions: it carries user data for transmission and simultaneously provides reference information for channel estimation. By making the same signal structure serve multiple purposes, the system achieves both data communication and channel characterization without requiring separate dedicated symbols.
2Loss of energy
If spectrum shaping filter is applied to DFT-s-OFDM, then PAPR is reduced and power efficiency is improved, but the effect diminishes for higher modulation schemes
Solution Approach 1:
The patent applies spectrum shaping filtering to the multiplexed sequence before DFT transformation, modifying the frequency domain characteristics of the signal. This parameter change in the signal processing chain achieves PAPR reduction while the filtering operation is modulation-agnostic, allowing the technique to work effectively across different modulation schemes including higher-order modulations.
3Speed
If one-shot transmission is used to achieve low latency, then transmission speed is improved, but channel estimation becomes difficult without dedicated reference symbols
Solution Approach 1:
The multiplexed sequence serves dual functions: it carries user data for transmission and simultaneously provides reference information for channel estimation. By making the same signal structure serve multiple purposes, the system achieves both data communication and channel characterization without requiring separate dedicated symbols.
Data Source
AI summary
Embodiments of the present disclosure relate to generating pre DFT RS and data multiplexed DFT-S-OFDM with excess bandwidth shaping. The RS and user data are transmitted in different OFDM symbols, such that channel estimation to equalize the data can be estimated clearly at the receiver. The present disclosure a method for transmitting a waveform is disclosed. The method comprising generating, by a transmitter, at least one of: at least one data sequence and at least one reference sequence (RS). Also the method comprises time-multiplexing the at least one data sequence with the at least one RS, to generate a multiplexed sequence, and generating a filtered-extended bandwidth DFT-s-OFDM symbol using the multiplexed sequence. Also, the method transmits RS and user data in one OFDM symbol with DFT-s-OFDM, which eventually offers low PAPR. Further, the method transmits only RS so that low PAPR is achieved.