Random Access Resource Allocation for Uplink Subframes
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Solution Overview
Problem
In modern cellular radio systems, the random access procedure is challenged by timing and power uncertainties in uplink transmissions, leading to potential collisions and inefficient resource allocation due to the difficulty in synchronizing timing and the need for complex contention resolution schemes.
Innovation Solution
The method involves mapping and allocating random access resources to uplink subframes, expressing these allocations in a way that reduces the amount of data needed for signaling, allowing for efficient configuration and resource management by spreading resources over time and frequency, thereby simplifying the random access process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple random access preambles are provided to distinguish between different requesting UEs, then the ability to resolve RA attempts improves, but the complexity of the RA procedure and signaling overhead increases
Solution Approach 1:
The patent segments the random access procedure into distinct phases: preamble selection from a pool, preamble transmission, and contention resolution. By dividing the RA process into manageable segments with clear state transitions, the system maintains high resolution accuracy through multiple preambles while reducing overall procedural complexity through structured organization.
Solution Approach 2:
The patent implements preliminary actions by pre-configuring pools of random access preambles and establishing contention resolution mechanisms before actual RA attempts occur. The eNodeB prepares resolution identifiers and state machines in advance, enabling efficient handling of multiple simultaneous RA requests without increasing real-time processing complexity.
2Reliability
If a random back off mechanism is implemented to handle collisions, then the reliability of RA success improves, but the time required for RA completion increases
Solution Approach 1:
The patent implements periodic random back-off intervals as part of the contention resolution mechanism. When collisions are detected, UEs are instructed to retry after randomized periodic intervals, which systematically distributes retry attempts over time. This periodic approach maintains high RA success rates by ensuring eventual access while managing time loss through structured retry scheduling rather than unbounded waiting.
3Reliability
If extra guard time is added to the PRACH slot to account for timing uncertainty, then the reliability of timing synchronization improves, but the time resource consumption increases
Solution Approach 1:
The patent applies partial guard time mechanisms where the guard period is optimized to cover the minimum necessary timing uncertainty rather than providing excessive protection. The system calculates guard time requirements based on actual cell size and propagation delay characteristics, implementing just enough guard time to ensure reliable timing synchronization while minimizing time resource consumption in PRACH slots.
4Measurement precision
If many different RA preambles are provided to distinguish requesting UEs, then the ability to resolve simultaneous RA attempts improves, but the signaling overhead and processing load increases
Solution Approach 1:
The patent implements local quality by organizing preambles into cell-specific pools where each cell is configured with a subset of available preambles tailored to its specific conditions (cell size, traffic load, interference characteristics). This local optimization allows each cell to maintain sufficient preamble diversity for accurate UE identification while reducing the overall system-wide signaling overhead compared to providing all preambles in every cell.
Data Source
AI summary
The invention relates to methods and communication devices in a network comprising the steps of mapping and allocating a first random access resource to a first frequency in an uplink subframe of a radio frame, and transmitting an expression on the radio channel expressing mapping of the first random access resource to use in relation to at least one uplink subframe.