Dedicated Random Access Preamble Validity Pattern for LTE
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Solution Overview
Problem
In LTE telecommunications systems, the random access procedure faces delays and collisions due to the shortage of dedicated random access preambles, leading to inefficiencies in uplink synchronization and resource allocation.
Innovation Solution
Introducing a validity pattern for dedicated random access preambles, where the radio base station assigns a dedicated preamble to a UE with an identification number and specifies the PRACH occurrences when it is valid for use, allowing the UE to perform random access efficiently and reducing collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dedicated random access preambles are assigned to UEs for contention-free random access, then collision risk is reduced and access reliability is improved, but the number of available dedicated preambles is limited causing delays when all preambles are in use
Solution Approach 1:
The patent applies dynamics by making the preamble availability dynamic through validity patterns. Instead of static dedicated preamble assignment, the system dynamically determines which preambles are valid for use in each PRACH occurrence based on current system state, allowing flexible reuse of preambles across different time instances while maintaining contention-free access when available.
Solution Approach 2:
The patent implements periodic action through validity patterns that repeat across PRACH occurrences. The validity pattern information indicates periodic intervals where dedicated preambles are valid for use, allowing the system to systematically reuse preambles in a periodic manner, thereby extending availability without increasing the total number of preambles.
2Loss of time
If the number of dedicated random access preambles is increased to reduce delays, then random access delay is reduced, but the device complexity and resource allocation complexity increase
Solution Approach 1:
The patent applies universality by making dedicated preambles serve multiple functions and multiple UEs across different time instances through validity patterns. The same dedicated preamble can be assigned to different UEs at different times, and the validity pattern mechanism provides a universal framework for managing preamble availability, reducing the need for additional dedicated preambles for each UE.
Solution Approach 2:
The patent changes parameters by introducing validity pattern parameters that control preamble availability. Instead of changing the number of preambles, the system changes the temporal parameters (validity patterns) of existing preambles, allowing flexible control of preamble availability without increasing the total number of preambles or managing complexity.
3Productivity
If dedicated preambles are assigned to multiple UEs simultaneously, then resource efficiency is improved, but the risk of collision increases when preambles are reused before previous assignments are complete
Solution Approach 1:
The patent applies segmentation by dividing the validity period of dedicated preambles into segments defined by validity patterns. Each validity pattern segment specifies when a preamble is valid for use, creating temporal segmentation that prevents overlapping usage conflicts. This segmentation allows multiple UEs to use the same preamble in different time segments without collision.
Solution Approach 2:
The system uses feedback mechanisms where the eNB monitors PRACH occurrences and tracks which UEs are using which preambles. Based on this feedback, the eNB dynamically updates validity patterns and reassigns preambles, ensuring that collision risk is minimized while maintaining high resource efficiency through coordinated reuse.
Data Source
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AI summary
The present invention relates to methods and apparatuses (radio base station (120, 600) and UE (110, 700) for enabling a UE to perform a random access. According to embodiments of the present invention, an identification number of a dedicated random access preamble is, in a message, transmitted together with information indicating in which channel or channels the preamble is valid for the UE. The UE (110, 700) can then use the received information and based on that information perform a random access.