Multicarrier Random Access Using Allowed RACH Configuration Sets
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Solution Overview
Problem
In wireless communications systems with multiple carriers, existing technologies face challenges in efficiently managing random access procedures due to ambiguity in selecting appropriate RACH resources, leading to increased blind decoding complexity and potential failure of uplink communications.
Innovation Solution
A method for managing random access resources in wireless communications systems with multiple carriers involves configuring an allowed RACH configuration set, which includes determining and managing PRACH/RACH configurations using system information, explicit signaling, and staggering RACH periods across carriers to reduce effective RACH period and improve resource selection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single UL carrier is used, then the RACH resource selection is simple, but the system cannot efficiently handle multiple carriers with ambiguous RACH resource selection
Solution Approach 1:
The patent segments the RACH configuration into multiple allowed configurations, each associated with specific UL carriers. The WTRU maintains an allowed RACH configuration set and selects from these segmented configurations based on the target UL carrier, avoiding the need to evaluate all possible carrier combinations and reducing selection complexity while supporting multiple carriers.
Solution Approach 2:
The patent applies local quality by associating different RACH configurations with specific UL carriers. Each UL carrier has its own set of allowed RACH configurations, allowing the WTRU to use carrier-specific configuration knowledge rather than requiring system-wide complexity, thus enabling multi-carrier operation with manageable local complexity.
2Adaptability or versatility
If multiple RACH resources are available across multiple carriers, then the random access flexibility is improved, but the blind decoding complexity increases
Solution Approach 1:
The patent implements preliminary action by pre-configuring and broadcasting allowed RACH configuration sets for multiple UL carriers before the random access procedure. The WTRU receives and stores these configurations in advance, so during random access it only needs to select from pre-processed configurations rather than performing complex real-time analysis, thus maintaining flexibility while reducing blind decoding complexity.
Solution Approach 2:
The patent uses feedback mechanisms where the eNB broadcasts allowed RACH configuration sets via system information blocks, and the WTRU feeds back its selected configuration and carrier choice during the random access procedure. This feedback loop allows the system to manage complexity by having the network provide structured guidance and the terminal report its decisions, reducing the blind decoding burden.
3Speed
If RACH period is reduced to improve access speed, then the random access response time is reduced, but the resource management complexity increases
Solution Approach 1:
The patent applies dynamics by allowing the effective RACH period to be reduced through carrier staggering while maintaining manageable resource management. The network dynamically configures different RACH periods for different UL carriers, and the WTRU dynamically selects the appropriate carrier and configuration based on current conditions. This dynamic approach enables faster access without requiring complex static resource management across all carriers.
Data Source
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AI summary
Method and apparatus for random access in multicarrier wireless communications are disclosed. Methods and apparatus are provided for physical random access channel (PRACH) resource signaling, PRACH resource handling, preamble and PRACH resource selection, random access response (RAR) reception, preamble retransmission, and transmission and reception of subsequent messages. A method for maintaining an allowed multicarrier uplink (UL) random access channel (RACH) configuration set by adding an UL carrier to the allowed RACH configuration set provided that a triggering event occurs and performing a random access (RA) procedure using the allowed RACH configuration set. A method for sending data in multicarrier wireless communications by determining a set of available UL carriers and selecting an UL carrier from the set of available UL carriers.