CFRA Preamble Allocation via Timer-Based Mode Switching
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Solution Overview
Problem
Current wireless communication systems face inefficiencies in random access procedures, particularly during handovers, due to limited contention-free random access preambles and potential interference from contention-based preamble usage, leading to increased latency and resource bottlenecks.
Innovation Solution
The proposed solution involves allocating user equipment-specific random access preambles and timing information, allowing user equipment to switch from contention-free to contention-based preambles based on a timer and timing information, optimizing preamble usage and reducing resource reservation conflicts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contention-free random access preambles are allocated to user equipment for handover, then handover reliability is improved, but the number of available preambles is limited causing resource bottlenecks
Solution Approach 1:
The system dynamically switches between contention-free and contention-based random access modes based on timer expiration and timing information. User equipment initially uses contention-free preambles for reliable handover, then transitions to contention-based preambles after timer expiration, allowing the system to adapt preamble allocation based on handover progress and timing conditions.
Solution Approach 2:
The system changes the timing parameter of preamble usage by providing timing information that indicates when user equipment should switch from contention-free to contention-based preambles. This timing control allows multiplexing of preambles across different time instants, effectively increasing the available preamble resources.
2Quantity of substance
If contention-based preambles are used during handover, then more preambles are available, but interference from contention-based usage increases access latency
Solution Approach 1:
The system performs preliminary allocation of contention-free preambles to user equipment before handover execution. This ensures that when handover occurs, user equipment can immediately use reserved preambles without waiting for contention-based access, thereby reducing access latency while still allowing broader preamble availability through the timer-based transition mechanism.
3Quantity of substance
If multiple user equipment share contention-free preambles, then resource utilization is improved, but timing coordination becomes complex
Solution Approach 1:
The system uses periodic timer mechanisms and timing information to coordinate preamble usage. Each user equipment has a timer that expires at predetermined intervals, and timing information specifies when preambles should be used. This periodic structure simplifies coordination by creating predictable, rhythm-based access patterns rather than requiring complex continuous coordination.
Data Source
AI summary
There is provided an apparatus comprising means for: receiving, at a user equipment from a first access point supporting a serving cell, one or more user equipment specific allocations of a random access preamble and timing information associated with the random access preamble, the timing information indicating when the user equipment is to use the associated random access preamble; responsive to the receiving, starting a timer; and sending, to a second access point supporting a target cell, a random access request including one of the one or more random access preambles, the included random access preamble being selected based on a value of the timer and the timing information.