Dynamic Modulation Selection for Two-Step RACH
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Solution Overview
Problem
Current wireless communication technologies, such as LTE and NR, face challenges in improving spectral efficiency and coverage for random access messages in two-step random access procedures, particularly in terms of signaling overhead and latency, while maintaining power efficiency and capacity.
Innovation Solution
A method where user equipment (UE) determines a set of modulations for random access messages based on signal strength thresholds, selecting between different modulation schemes such as QPSK, 16 QAM, or π/2 BPSK to optimize coverage and transmission efficiency, and transmits these messages using a physical uplink shared channel (PUSCH).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed modulation scheme is used for random access messages, then device complexity is reduced, but spectral efficiency and coverage are limited
Solution Approach 1:
The patent implements dynamic modulation selection where the UE determines the modulation scheme (QPSK, 16QAM, or π/2-BPSK) based on real-time signal strength measurements compared to thresholds. This dynamic adaptation allows the system to optimize spectral efficiency by using higher-order modulations when channel conditions permit, while maintaining reliability when conditions are poor, thereby resolving the contradiction between fixed complexity and variable performance.
Solution Approach 2:
The patent changes the modulation parameter based on signal strength conditions. By monitoring signal quality and selecting from multiple modulation schemes (QPSK for poor conditions, 16QAM for good conditions, π/2-BPSK as alternative), the system adapts transmission parameters to channel conditions, improving spectral efficiency without requiring complex device architecture.
2Productivity
If higher-order modulations are used for random access messages, then spectral efficiency is improved, but coverage is reduced
Solution Approach 1:
The patent dynamically selects modulation schemes based on measured signal strength. When signal strength exceeds a threshold, higher-order modulations like 16QAM are used to improve spectral efficiency. When signal strength is below the threshold, more robust modulations like QPSK or π/2-BPSK are selected to ensure coverage and reliable delivery, thus dynamically balancing spectral efficiency and coverage requirements.
Solution Approach 2:
The patent changes modulation parameters adaptively based on channel conditions. By comparing signal strength against thresholds and selecting from multiple modulation options, the system optimizes the trade-off between spectral efficiency (higher with 16QAM) and coverage/reliability (higher with QPSK and π/2-BPSK), ensuring both objectives are met under different conditions.
3Productivity
If signal strength threshold-based modulation selection is implemented, then spectral efficiency and coverage are optimized, but device complexity increases
Solution Approach 1:
The patent segments the signal strength range into distinct regions defined by thresholds, with each segment associated with a specific modulation scheme. This segmentation simplifies the decision process compared to continuous optimization, as the UE only needs to compare measured signal strength against predefined thresholds to determine the appropriate modulation, reducing computational complexity while maintaining optimization benefits.
Solution Approach 2:
The patent implements parameter changes based on threshold comparisons rather than complex optimization algorithms. By defining specific signal strength thresholds and associated modulation schemes, the system achieves spectral efficiency optimization through simple threshold-based decision logic, minimizing the increase in device complexity while maximizing performance benefits.
4Adaptability or versatility
If multiple modulation schemes are supported, then adaptability to different channel conditions is improved, but processing complexity increases
Solution Approach 1:
The patent segments channel conditions into distinct categories (good, poor, marginal) based on signal strength thresholds, with each segment mapped to a specific modulation scheme. This segmentation approach provides adaptability to different channel conditions while keeping processing simple, as the UE only needs to measure signal strength and select the corresponding pre-defined modulation rather than performing complex analysis for each modulation option.
Solution Approach 2:
The patent changes modulation parameters based on channel condition assessment through threshold comparison. By supporting multiple modulation schemes (QPSK, 16QAM, π/2-BPSK) with simple threshold-based selection logic, the system achieves high adaptability to varying channel conditions without proportionally increasing processing complexity, as the decision mechanism remains straightforward.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may determine a set of modulations for a random access message associated with a two-step random access channel (RACH) procedure. The set of modulations may be either a first set of modulations or a second set of modulations that is different from the first set of modulations. The set of modulations may be determined based at least in part on whether a signal strength satisfies a signal strength threshold. The UE may transmit the random access message based at least in part on the determined set of modulations. The random access message may include a physical uplink shared channel modulated using the determined set of modulations. Numerous other aspects are provided.