NR RACH Procedure Selection Under Latency and Collision Constraints
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Solution Overview
Problem
Existing wireless communication systems face challenges in selecting the optimal New Radio (NR) Random Access Channel (RACH) procedure, particularly in scenarios with high network load or dual-stack UEs, leading to increased latency, inefficient resource use, and potential collisions.
Innovation Solution
A method and system for selecting the optimal NR RACH procedure based on Received Signal Strength Indicator (RSRP) information and idle periods, and prioritizing stacks in dual-SIM UEs to manage simultaneous transmissions, using a RACH optimizer module to determine the most efficient RACH type (two-step or four-step) and handle conflicts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the two-step RACH procedure is selected to reduce access latency, then connection establishment speed is improved, but the risk of collision increases in high network load scenarios
Solution Approach 1:
The patent dynamically changes the RACH procedure parameters by selecting between two-step and four-step procedures based on RSRP thresholds and network conditions. When RSRP is above a threshold, the two-step procedure is selected for faster access; when below, the four-step procedure is selected to reduce collision risk, thus adapting parameters to resolve the contradiction between speed and reliability
Solution Approach 2:
The patent implements dynamic selection of RACH procedure types based on real-time RSRP measurements and network load conditions. The system transitions between static procedure choices and dynamic adaptation, allowing the UE to switch between two-step and four-step procedures according to current channel conditions, resolving the trade-off between latency and collision risk
2Reliability
If the four-step RACH procedure is selected to reduce collision risk, then reliability is improved, but access latency increases
Solution Approach 1:
The patent changes the RACH procedure parameters dynamically by selecting four-step procedure when RSRP is below a threshold or network load is high, reducing collision risk at the cost of increased latency. This parameter adaptation resolves the contradiction by accepting longer access time in exchange for higher reliability in challenging conditions
3Productivity
If dual-SIM UEs perform simultaneous RACH transmissions on multiple stacks, then connection establishment parallelism is improved, but resource conflicts and collisions increase
Solution Approach 1:
The patent applies preliminary action by checking for transmission conflicts before initiating simultaneous RACH procedures on multiple stacks. The UE determines whether transmission occasions overlap in time and applies priority rules or delays to prevent collisions, ensuring that parallel connection attempts do not result in resource conflicts
Solution Approach 2:
The patent introduces an intermediary conflict resolution mechanism that mediates between multiple stacks attempting simultaneous transmissions. When a conflict is detected, the system applies priority rules (e.g., RACH occasion index, SSB index) to determine which transmission proceeds, acting as a mediator to prevent collisions while maintaining parallel processing capability
Data Source
AI summary
A method executed by a User Equipment (UE) including receiving, from a network device, system information including first Physical RACH (PRACH) configuration information associated with a two-step PRACH procedure and second PRACH configuration information associated with a four-step PRACH procedure, detecting that the two-step PRACH procedure meets criteria for transmitting at least one message, determining whether a first value associated with the two-step PRACH procedure is greater than or less than a second value associated with the four-step PRACH procedure, determining whether an idle period is sufficient between two consecutive occasions associated with the two-step PRACH procedure, and performing one of selecting the four-step PRACH procedure when the first value is greater than the second value and the idle period is sufficient, or selecting the two-step PRACH procedure when the first value is less than or equal to the second value, and the idle period is not sufficient.