Orthogonal Code Covers for Low-PAPR Multiuser DFT-s-OFDM
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Solution Overview
Problem
Existing communication systems face challenges in efficiently transmitting DFT-s-OFDM symbols due to high Peak Power to Average Ratio (PAPR), intermodulation distortion, and phase noise in mm wave systems, especially in scenarios with high mobility and phase variations, leading to inefficient bandwidth utilization and channel tracking issues.
Innovation Solution
The method involves time-multiplexing data and reference sequences in a single slot of the DFT-s-OFDM symbol, followed by DFT processing to generate DFT-s-OFDM symbols, which are then processed through shaping filters and sub-carrier mapping to reduce PAPR and enable efficient transmission, while allowing for channel and phase tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If OFDM is used for uplink transmission, then bandwidth utilization is improved, but Peak Power to Average Ratio (PAPR) increases
Solution Approach 1:
The patent segments the uplink transmission into two distinct modes: OFDM mode for downlink-centric slots and DFT-s-OFDM mode for uplink-centric slots. This segmentation allows each mode to be optimized for its specific use case, with DFT-s-OFDM providing lower PAPR for uplink transmissions while OFDM maintains high bandwidth utilization for downlink communications.
Solution Approach 2:
The system dynamically switches between OFDM and DFT-s-OFDM modes based on the slot type and transmission requirements. The gNodeB configures the UE to use different modulation schemes depending on whether the slot is downlink-centric or uplink-centric, enabling adaptive optimization of PAPR and bandwidth utilization in real-time.
2Reliability
If data sequence and reference sequence are time multiplexed in separate slots, then transmission reliability is improved, but transmission time increases
Solution Approach 1:
The patent merges the data sequence and reference sequence transmission into a single slot by using DFT-s-OFDM modulation. Both sequences are transmitted simultaneously in the time domain, with the reference sequence enabling channel equalization while the data sequence carries user information, thereby reducing transmission time without compromising reliability.
Solution Approach 2:
The system transitions from time-domain multiplexing to frequency-domain multiplexing through DFT-s-OFDM. By transforming the time-multiplexed sequences into the frequency domain, the reference and data sequences can be transmitted simultaneously without interference, effectively adding a frequency dimension to the transmission.
3Device complexity
If PUCCH is transmitted in adjacent RBs with PUSCH, then device complexity is reduced, but intermodulation distortion increases
Solution Approach 1:
The patent extracts the PUCCH transmission from the PUSCH resource blocks by allocating dedicated control resource sets for PUCCH. This separation removes the source of intermodulation distortion caused by simultaneous PUCCH-PUSCH transmission in the same RBs, while maintaining simple FDM multiplexing through frequency allocation.
Solution Approach 2:
The system introduces frequency division as an intermediary mechanism to separate PUCCH and PUSCH transmissions. By allocating different frequency resources for control and data channels, the system mediates between the need for simple multiplexing and the requirement to avoid intermodulation distortion.
4Device complexity
If SRS is transmitted only within long UL duration, then device complexity is reduced, but adaptability decreases
Solution Approach 1:
The patent implements dynamic SRS transmission configuration where the gNodeB can flexibly configure SRS to be transmitted in either long UL duration or short UL duration based on channel conditions and system requirements. This dynamic adaptability allows the system to optimize for different scenarios without increasing device complexity.
Solution Approach 2:
The system changes the transmission parameter (UL duration type) based on operational needs. By allowing SRS to be configured in different UL duration contexts, the system adapts to varying channel conditions and mobility scenarios while maintaining manageable complexity through parameter-based configuration.
Data Source
AI summary
The present disclosure discloses a method and a system for providing a code cover to Orthogonal Frequency Division Multiplexing (OFDM) symbols in a multiple user system. A data sequence is received from each of a plurality of users. Further, a reference sequence is generated for the data sequence of each of the plurality of users. Each of the reference sequence is multiplied with a code cover which are orthogonal to each other. Each of the reference sequence is time multiplexed with corresponding data sequence, to generate a corresponding multiplexed sequence. Further, a Discrete Fourier Transform (DFT) is performed on each of the multiplexed sequence to generate a corresponding DFT-spread-Orthogonal Frequency Division Multiplexing (DFT-s-OFDM) symbol. Lastly, the corresponding DFT-s-OFDM symbol is processed for transmitting over corresponding one or more channels.