Dynamic Cyclic Prefix Length for Two-Step Random Access
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Solution Overview
Problem
In wireless communication, the two-step random access procedure faces interference issues due to the lack of timing advance instructions for UEs, leading to conflicts and increased signaling overheads, particularly in the two-step random access scenario where data channels are sent without pre-configured timing adjustments.
Innovation Solution
Determine the cyclic prefix (CP) length for data channels based on the CP length of the random access preamble and the cyclic shift interval to avoid interference and reduce signaling overheads, by setting the CP length to be greater than or equal to the smaller of these two values, thereby improving resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the CP length of the data channel is increased to avoid interference between multiple UEs, then the reliability of data transmission is improved, but the CP overhead increases, reducing resource utilization
Solution Approach 1:
The patent dynamically adjusts the CP length parameter based on the detected random access preamble sequence. Different preamble sequences are associated with different CP length configurations, allowing the system to optimize between reliability and overhead by selecting appropriate CP lengths matched to the specific transmission scenario and interference conditions.
Solution Approach 2:
The system transitions from a static CP length configuration to a dynamic one where the CP length is selected based on the random access preamble detection results. This dynamic adaptation allows the CP length to be optimized in real-time according to the actual channel conditions and interference levels, resolving the contradiction between maintaining high reliability and minimizing overhead.
2Reliability
If timing advance instructions are provided to UEs to eliminate interference, then the data transmission reliability is improved, but the signaling overhead increases
Solution Approach 1:
The system performs preliminary timing adjustment through the association between random access preamble sequences and CP length configurations. By pre-configuring multiple UEs with different preamble sequences that correspond to different CP lengths, the timing alignment is achieved in advance during the random access phase, eliminating the need for subsequent timing advance signaling and reducing overall signaling overhead.
Solution Approach 2:
The random access preamble sequence acts as an intermediary that carries timing information implicitly. Instead of directly signaling timing advance values, the system uses the preamble sequence selection as a mediator to convey timing alignment information, which is then reflected in the CP length configuration for data channel transmission, thereby reducing explicit signaling overhead.
3Productivity
If the CP length is set to be equal to the cyclic shift interval to minimize overhead, then resource utilization is improved, but interference between UEs may increase
Solution Approach 1:
The patent applies different CP length qualities to different UE groups based on their preamble sequence selections. Instead of using a uniform CP length for all UEs, the system configures locally optimized CP lengths tailored to each UE's specific transmission characteristics and interference environment, allowing resource-efficient operation while maintaining adequate interference protection for each local context.
Data Source
AI summary
A method includes determining, based on a cyclic prefix (CP) length corresponding to a random access preamble and a time length corresponding to a cyclic shift interval, a CP length corresponding to a data channel, and sending the data channel. The method may be applied to a random access procedure.