LTE Random Access Timing Adjustment via Cause Indicator
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Solution Overview
Problem
In LTE cellular networks, the random access channel (RACH) procedure faces challenges in determining the correct time offset for preamble transmission due to different causes, leading to ambiguity and inefficiency in layer L1's ability to manage the allowed transmission time for RACH preamble transmission.
Innovation Solution
A method where a higher layer transmits an indicator to a lower layer, including a cause value that specifies the reason for the RACH preamble transmission, allowing the lower layer to adjust the timing accordingly, enabling layer L1 to determine the allowed transmission time offset and adjust preamble transmission timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the lower layer determines preamble transmission timing without cause information, then the procedure is simple, but timing accuracy deteriorates due to ambiguity
Solution Approach 1:
The higher layer performs preliminary action by determining the cause of RACH preamble transmission in advance and notifying the lower layer through an indicator before the actual transmission occurs. This allows the lower layer to accurately determine the timing offset without ambiguity, resolving the technical contradiction between timing accuracy and procedure complexity.
2Measurement precision
If the higher layer determines transmission timing, then timing accuracy improves, but the lower layer loses autonomy and increases dependency
Solution Approach 1:
The invention segments the timing determination task by dividing responsibilities between layers: the higher layer determines the cause and sets the timing offset, while the lower layer autonomously applies the offset to determine the actual transmission time. This segmentation maintains layer autonomy while improving timing accuracy, resolving the technical contradiction.
3Reliability
If fixed timing offset is used for all causes, then the procedure is straightforward, but collision probability increases due to insufficient timing differentiation
Solution Approach 1:
The invention applies local quality by assigning different timing offsets specifically to different causes of RACH preamble transmission. Instead of using a uniform timing offset for all scenarios, the higher layer configures cause-specific offsets, allowing the system to differentiate timing locally for each cause type. This improves collision avoidance while maintaining manageable complexity through targeted differentiation.
Data Source
AI summary
The invention relates to a method of random access, comprising: a higher layer instructs the lower layer to transmit a random access preamble, wherein the timing transmission of the random access preamble is adjusted by the lower layer according the triggered resources.