OTFDM Downlink Symbol Time-Multiplexing for Low-Latency 5G
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Solution Overview
Problem
Current 5G standards face challenges with low power-amplifier efficiency and high latency due to the use of OFDM waveforms that require separate symbols for data and reference signals, leading to increased latency and overhead, which is not suitable for future wireless communication systems requiring extremely low latency and high energy efficiency.
Innovation Solution
The implementation of Orthogonal Time Frequency-Division Multiplexing (OTFDM) symbols that time-multiplex synchronization signals, control channels, and data channels within a single OFDM symbol, allowing for low PAPR, high PA efficiency, and low latency transmission using multiple antenna ports or beams, while supporting flexible RS overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional OFDM waveform is used with separate symbols for data and reference signals, then frequency multiplexing is achieved, but latency doubles and RS overhead increases to 50%
Solution Approach 1:
The patent merges data and reference signals into a single OTFDM symbol by time-multiplexing them within the same symbol duration. The transmitter time-multiplexes at least one of PSS, SSS, and PBCH sequences to generate a multiplexed sequence, which is then processed to generate an OTFDM symbol. This combining approach eliminates the need for separate dedicated RS symbols, reducing latency from two symbols to one symbol while lowering RS overhead from 50% to approximately 25%.
2Use of energy by moving object
If DFT-S-OFDM is used for high energy efficiency, then power amplifier efficiency improves, but a dedicated OFDM symbol is required for RS transmission resulting in two symbols duration and 50% RS overhead
Solution Approach 1:
The patent combines data and reference signals within a single OTFDM symbol, maintaining the low-PAPR properties of DFT-S-OFDM for high power amplifier efficiency while eliminating the need for a separate dedicated RS symbol. The time-multiplexed structure within one symbol achieves both energy efficiency and reduced transmission duration.
Solution Approach 2:
The patent transitions from frequency multiplexing (conventional OFDM) to time multiplexing within a single symbol (OTFDM). By organizing data and RS in the time dimension rather than frequency dimension, the system achieves low latency transmission while maintaining the energy efficiency benefits of DFT-S-OFDM waveform.
3Productivity
If conventional slot structure with multiple OFDM symbols is used, then frequency multiplexing of data and control is achieved, but latency increases due to slot duration being multiple symbols
Solution Approach 1:
The patent employs time multiplexing within a single OFDM symbol instead of using multiple symbols in the frequency domain. This dimensional shift from frequency-based multiplexing to time-based multiplexing within one symbol enables extremely low latency transmission while maintaining the capacity to carry multiple channels (PSS, SSS, PBCH) through temporal separation.
Data Source
AI summary
Embodiments of the present disclosure relate methods and systems for transmitting downlink Orthogonal time frequency-division multiplexing (OTFDM) symbol. The method comprising time-multiplexing, by the transmitter, at least one of a primary synchronization signal (PSS) sequence, a secondary synchronization signal (SSS) sequence and a physical broadcast channel (PBCH) sequence to generate a multiplexed sequence. Also the method comprises processing, by the transmitter, the multiplexed sequence to generate a SS Block OTFDM symbol.