5G Two-Step Random Access for Variable MsgA Payloads
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Solution Overview
Problem
The 5G wireless communication system faces challenges in efficiently supporting variable sizes of message A (MsgA) payloads in the 2 step random access procedure, leading to resource wastage for smaller payloads and ambiguity in network responses, particularly for UEs near and far from the gNB.
Innovation Solution
Configuring multiple MsgA PUSCH resource pools with varying sizes and repetition levels to accommodate variable payload sizes and ensuring reliable transmission, along with methods to differentiate network responses for 2 step and 4 step RA procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single MsgA PUSCH resource pool is configured, then device complexity is reduced, but adaptability to variable payload sizes deteriorates
Solution Approach 1:
The MsgA PUSCH resource pool is segmented into multiple sub-pools, each configured with different payload size capabilities and repetition levels. This allows the system to handle variable payload sizes efficiently while keeping each individual sub-pool configuration relatively simple.
Solution Approach 2:
The resource pool configuration is made dynamic by allowing UEs to select appropriate sub-pools based on their payload size requirements and channel conditions. This dynamic adaptation enables the system to balance between complexity and versatility.
2Adaptability or versatility
If MsgA PUSCH resource is allocated for maximum payload size, then adaptability to large payloads is improved, but resource wastage for smaller payloads increases
Solution Approach 1:
The resource pool is divided into multiple sub-pools with different size configurations. UEs select the appropriate sub-pool based on their actual payload size, ensuring that resources are allocated efficiently without over-provisioning for maximum size in all cases.
Solution Approach 2:
Different sub-pools are optimized for different payload size requirements. Each sub-pool has local quality characteristics (repetition levels, resource allocation) matched to its intended payload size range, avoiding the inefficiency of uniform maximum-size allocation across all UEs.
3Device complexity
If network response format is unified, then device complexity is reduced, but measurement precision in identifying procedure type deteriorates
Solution Approach 1:
Different response formats are introduced to clearly indicate whether the response is for 2-step or 4-step RA procedure. This is analogous to using different colors to distinguish between different types of responses, making procedure type identification unambiguous while maintaining manageable device complexity.
Solution Approach 2:
A new indication field or format element acts as an intermediary marker in the network response to clearly differentiate between 2-step and 4-step RA procedures. This intermediary element provides precise procedure type identification without significantly increasing overall device complexity.
4Reliability
If repetition level is increased for reliable transmission, then reliability is improved, but resource wastage increases
Solution Approach 1:
The repetition level is made dynamic and configurable based on UE selection of different sub-pools and current channel conditions. This allows the system to achieve reliable transmission when needed while avoiding excessive repetition (and associated resource wastage) when channel conditions are good or payload size is small.
Solution Approach 2:
Different sub-pools are configured with different repetition levels appropriate to their intended use cases. Sub-pools for smaller payloads or better channel conditions use lower repetition levels, while sub-pools for larger payloads or worse conditions use higher repetition levels, optimizing the balance between reliability and resource consumption.
Data Source
AI summary
A communication method and system for converging a fifth generation (5G) communication system for supporting higher data rates beyond a fourth generation (4G) system with a technology for Internet of things (IoT) are provided. The communication method and system may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. A method by a terminal configured with at least one serving cell for performing a random access (RA) procedure is provided. The method includes measuring downlink reference signal received power (DL RSRP) of a serving cell on which the RA procedure is initiated, determining whether the DL RSRP of the serving cell is greater than a threshold, and performing a two-step RA procedure based on the DL RSRP of the serving cell being greater than the threshold.