CSI-RS-Linked PRACH Occasions for Flexible Two-Step Random Access
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Solution Overview
Problem
The existing four-step random access procedure in NR systems is inefficient for larger cells due to the need for timing advance, and there is a lack of flexible configuration of random access channel occasions for two-step random access procedures.
Innovation Solution
Configuring a set of physical random access channel (PRACH) occasions associated with channel state information reference signals (CSI-RS) for two-step random access, allowing for flexible configuration of ROs that can be shared or dedicated, enabling efficient two-step random access without requiring four-step random access resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If four-step random access procedure is used, then timing advance can be achieved, but access efficiency deteriorates for larger cells
Solution Approach 1:
The patent extracts the timing advance function from the four-step random access procedure and integrates it into the two-step procedure. Specifically, the gNB provides timing advance information in the downlink message (msg2) of the two-step procedure, eliminating the need for the separate uplink message exchange required in four-step procedures while maintaining timing synchronization capability.
Solution Approach 2:
The patent merges the random access preamble transmission and uplink data transmission into a single uplink message (msgA) in the two-step procedure. This consolidation reduces the number of round-trip exchanges from four steps to two steps, improving access efficiency while the gNB provides timing advance in the response message to maintain synchronization.
2Adaptability or versatility
If four-step random access resources are allocated, then random access can be performed, but flexibility for two-step random access configuration is insufficient
Solution Approach 1:
The patent segments the random access resources into separate configurations for two-step and four-step procedures. Specifically, it introduces dedicated parameters (msgA-PRACH-ConfigurationIndex, msgA-RO-FDM, msgA-FrequencyStart) for two-step random access PRACH occasions, separating them from four-step procedure configurations. This allows independent optimization and flexible configuration of two-step random access resources without being constrained by four-step resource allocations.
3Productivity
If two-step random access is implemented without dedicated RO configuration, then implementation is simplified, but access efficiency for specific scenarios deteriorates
Solution Approach 1:
The patent introduces dynamic and flexible configuration parameters for two-step random access PRACH occasions. The gNB can configure msgA-PRACH-ConfigurationIndex, msgA-RO-FDM, and msgA-FrequencyStart parameters to dynamically adjust PRACH resource allocation based on network conditions, cell size, and specific access scenarios. This enables optimized access efficiency for different scenarios while maintaining manageable configuration complexity through standardized parameter sets.
Data Source
AI summary
Methods, an access network node and a terminal device for random access procedure are disclosed. According to an embodiment, the access network node transmits a signaling message which configures a set of physical random access channel (PRACH) occasions (ROs) associated with channel state information reference signal (CSI-RS) for two-step random access procedure.