RACH Selection Information for Carrier Aggregation Random Access
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Solution Overview
Problem
In LTE-A systems, User Equipment (UE) faces difficulties in determining which Random Access Channel (RACH) carrier to use for the random access process when multiple carriers are allocated, leading to inefficiencies in resource allocation.
Innovation Solution
A method where the base station configures and transmits Random Access Channel (RACH) selection information to the UE, which includes pathloss threshold and Probability Factors (PFs), allowing the UE to select and use the appropriate uplink carrier for random access based on available PRACH resources and channel conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple carriers are allocated to a single UE in LTE-A system, then transmission bandwidth and data rate are improved, but the UE cannot determine which RACH carrier to use for random access process
Solution Approach 1:
The eNB performs preliminary configuration by providing RACH selection information to the UE before the random access process occurs. This includes pre-configuring the UE with multiple RACH configuration sets, each associated with specific carriers and pathloss thresholds, so that when random access is needed, the UE can immediately select the appropriate carrier without requiring real-time determination.
Solution Approach 2:
The patent introduces RACH selection information as an intermediary mechanism between the eNB and UE. This selection information acts as a mediator that guides the UE in choosing the correct RACH carrier by providing configuration sets that include pathloss thresholds and carrier associations, thereby resolving the ambiguity in carrier selection.
2Measurement precision
If multiple RACH configuration sets are provided to UE, then carrier selection accuracy is improved, but system complexity increases
Solution Approach 1:
The patent segments the RACH configuration into multiple distinct sets, where each set corresponds to specific carriers and pathloss conditions. This segmentation allows the UE to handle complex carrier selection by dividing the problem into manageable configurations, each with clear association rules and selection criteria.
Solution Approach 2:
The patent utilizes parameter changes, specifically pathloss thresholds, to dynamically select between different RACH configuration sets. By changing the threshold parameter based on current channel conditions, the system achieves accurate carrier selection without requiring the UE to process all configuration sets simultaneously, thereby managing complexity.
Data Source
AI summary
A random access method of a User Equipment (UE) in a wireless communication system supporting carrier aggregation which allows transmitting data on multiple carriers is provided. A random access method for a wireless communication system supporting carrier aggregation according to the present invention includes receiving, at a terminal, Random Access Channel (RACH) selection information necessary for random access, the RACH selection information being transmitted by a base station; selecting, when the random access is triggered, an uplink carrier on which the random access is attempted based on the RACH selection information; and attempting the random access on the selected uplink carrier.