Dynamic MCS Adaptation for Grant-less Uplink Random Access
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Solution Overview
Problem
Current wireless communication systems lack an efficient mechanism for link adaptation in uplink grant-less random access, leading to suboptimal spectrum usage and latency issues, especially for applications requiring low latency and reliable transmissions.
Innovation Solution
Implementing a method for dynamic modulation and coding scheme (MCS) adaptation based on uplink long-term measurements, allowing for either upgrading or downgrading the MCS in response to changing channel conditions, thereby optimizing transmission efficiency and supporting more users.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed robust MCS such as QSPK is used in random access channel, then transmission reliability is improved, but spectrum efficiency deteriorates
Solution Approach 1:
The patent implements dynamic MCS selection where the MCS is no longer fixed but adapts based on channel conditions. The base station measures uplink channel quality and selects appropriate MCS from multiple options (QSPK, 64QAM, 256QAM) based on current channel state, transforming the static MCS system into a dynamic one that optimizes both reliability and efficiency
Solution Approach 2:
The patent changes the MCS parameter based on measured channel conditions. When channel quality is good, higher order modulation (256QAM) and higher coding rates are used; when channel quality is poor, more robust schemes (QSPK with lower coding rates) are selected. This parameter adaptation resolves the contradiction between reliability and spectrum efficiency
2Quantity of substance
If more aggressive MCS are used to support more users, then user capacity is improved, but transmission reliability deteriorates
Solution Approach 1:
The patent adjusts MCS parameters dynamically based on individual user channel conditions. Users with good channel conditions can use aggressive MCS (256QAM, high coding rates) to increase capacity, while users with poor conditions automatically receive more robust configurations, maintaining reliability across the entire user base
Solution Approach 2:
Different MCS configurations are applied to different users based on their local channel conditions. Instead of using a uniform MCS for all users, the system tailors the modulation and coding parameters to each user's specific situation, allowing aggressive MCS for capable users while ensuring reliability for others
3Reliability
If a robust MCS is used for random access channel, then transmission success probability is improved, but latency increases
Solution Approach 1:
The patent implements dynamic MCS selection that responds to real-time channel conditions. When channels are favorable, aggressive MCS reduces the number of retransmissions needed, lowering latency. When channels are poor, robust MCS ensures first-transmission success, also reducing latency. This dynamic adaptation eliminates the need to always use conservative MCS
Solution Approach 2:
The base station measures uplink channel quality and uses this feedback to select appropriate MCS. This closed-loop feedback mechanism allows the system to adapt MCS based on actual channel state, optimizing both reliability and latency by avoiding unnecessary retransmissions
Data Source
AI summary
Embodiments are provided for a scheme of link adaptation (LA) in uplink grant-less random access (RA) communications. The scheme includes changing a modulation and coding (MCS) of a user, instead of using a fixed MCS over time, as the user link, channel, or non-link conditions vary during the RA communications. In an embodiment, a transmission point (TP) receives from a UE a packet encoded using a MCS, and detects a condition associated with uplink measurements or other non-link based condition of the UE. The TP then initiates an upgrade or a downgrade of the MCS in accordance with the condition, and signals the UE indicating a second MCS as a result. The UE thus sends a second packet encoded using the second MCS. In another embodiment, the UE initiates the MCS change in accordance to detecting a link or non-link based condition, such as change of mobility.