Scalable OFDM Numerology for Wireless Network Adaptability
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Solution Overview
Problem
Conventional wireless networks face limitations in accommodating diverse frequency bands and device types due to fixed numerologies, which are inadequate for high-speed mobility and high-frequency bands, and do not efficiently support low-cost, narrow bandwidth devices.
Innovation Solution
A scalable orthogonal frequency division multiplexing (OFDM) numerology system that allows for flexible configuration of subcarrier spacing, cyclic prefix lengths, and transmission time intervals, enabling backward compatibility with LTE while accommodating various applications and environments through integer scalable relationships and multiple parameter options.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single subcarrier spacing of 15 kHz is used in LTE networks, then backward compatibility and standardization are maintained, but the system cannot accommodate high-speed mobility scenarios with high Doppler frequency shift
Solution Approach 1:
The patent implements dynamic numerology configuration where subcarrier spacing and cyclic prefix lengths are adjusted based on channel conditions, mobility scenarios, and service requirements. The system transitions from fixed LTE numerology to flexible 5G numerology that adapts to different transmission scenarios, enabling support for both high-speed mobility and low-cost devices through appropriate parameter selection.
Solution Approach 2:
The patent changes key OFDM parameters including subcarrier spacing (scaling by factor 2^m), cyclic prefix length (scaling by factor 2^n), and transmission time interval duration to accommodate different scenarios. By modifying these parameters, the system can handle high Doppler shifts in mobility scenarios while also supporting narrow bandwidth operations for low-cost devices.
2Reliability
If subcarrier spacing is increased to accommodate high Doppler frequency shift in high-speed mobility scenarios, then mobility performance is improved, but energy consumption increases and coverage is reduced
Solution Approach 1:
The patent applies different numerology configurations to different time-frequency resources based on local channel conditions and service requirements. High subcarrier spacing is applied only when needed for mobility robustness, while lower spacing is used for energy-efficient operations, optimizing the trade-off between reliability and energy consumption on a per-resource basis.
3Use of energy by moving object
If narrow frequency bandwidth is used by low-cost devices for MTC or D2D communications, then coverage is enhanced and energy is saved, but the fixed 15 kHz subcarrier spacing becomes inefficient
Solution Approach 1:
The patent enables low-cost devices to use narrower subcarrier spacings (e.g., 7.5 kHz or lower) and appropriately scaled cyclic prefix lengths for narrowband MTC and D2D operations. This parameter flexibility allows devices to operate efficiently in narrow bandwidths while maintaining robustness against multipath effects through scaled cyclic prefix configurations.
4Adaptability or versatility
If fixed LTE numerology parameters are used, then implementation simplicity is maintained, but the system cannot efficiently support diverse applications including high-frequency bands and varying mobility scenarios
Solution Approach 1:
The patent segments the 5G NR parameter space into discrete, standardized configurations (e.g., subcarrier spacing of 15×2^m kHz, cyclic prefix lengths of 4.69×2^n μs). This segmentation provides a manageable set of numerology options that balance flexibility with implementation feasibility, allowing devices to support diverse applications without requiring continuous parameter adjustment.
Data Source
AI summary
For a wireless communications system, scalable orthogonal frequency division multiplexing (OFDM) numerology is incorporated in a manner that can apply to radio link transmissions in future wireless network for frequency division duplex (FDD) and time division duplex (TDD) communications.