Two-Step RACH Procedure for Reduced Random Access Time
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Solution Overview
Problem
The existing RACH procedures in wireless communication networks often take longer than desired, necessitating a more efficient approach.
Innovation Solution
A two-step random access channel procedure is implemented, where a preamble is transmitted in a first time slot, followed by an uplink data transmission in a second time slot with a specific time offset, and a response message containing a radio network temporary identifier (RNTI) is received, using distinct calculation formulas for RNTI in the two-step and four-step procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional four-step RACH procedure is used, then the access process is more comprehensive and reliable, but the access time is longer
Solution Approach 1:
The patent combines the preamble transmission and uplink data transmission into a single first step, and merges the random access response and contention resolution into a single second step. This merging of message exchanges reduces the number of round trips from four to two, thereby reducing access time while maintaining the essential functions of each step through integrated message structures.
Solution Approach 2:
The patent segments the random access procedure into distinct time slots with specific offsets. The first step occurs in a first time slot with preamble and uplink data, the second step in a second time slot with random access response, and the third step in a third time slot with contention resolution. This temporal segmentation allows parallel processing of multiple functions within reduced timeframes.
2Loss of time
If a two-step RACH procedure is implemented, then the access time is reduced, but the procedure complexity increases
Solution Approach 1:
The patent changes the temporal parameters of message transmission by defining specific time slots and time offsets. The first time slot contains both preamble and uplink data transmissions, the second time slot contains the random access response, and the third time slot contains contention resolution. These parameterized time slot definitions provide a structured framework that manages complexity through standardized timing relationships.
Solution Approach 2:
The patent introduces time slot structures and time offset parameters as intermediaries that mediate between the reduced step count and the required functional complexity. These temporal intermediaries organize the compressed procedure into manageable segments with clear boundaries and relationships, making the simplified two-step process implementable with controlled complexity.
3Measurement precision
If distinct RNTI calculation formulas are used for two-step and four-step procedures, then the identification accuracy is improved, but the calculation complexity increases
Solution Approach 1:
The patent applies different RNTI calculation formulas tailored to specific procedure types. The first formula is specifically designed for two-step RACH procedures while the second formula is designed for four-step RACH procedures. This local optimization ensures each formula is precisely suited to its intended use case, improving identification accuracy for each specific scenario.
Solution Approach 2:
The patent changes the calculation parameters based on the procedure type. By selecting different formulas based on whether a two-step or four-step procedure is being performed, the system adapts the RNTI calculation to match the specific temporal and structural characteristics of each procedure variant, ensuring accurate identification while managing complexity through conditional selection.
Data Source
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AI summary
Apparatuses, methods, and systems are disclosed for performing a two-step random access channel procedure. One method (700) includes determining (702) whether to perform a two-step random access channel procedure or a four-step random access channel procedure. The method (700) includes, in response to determining to perform the two-step random access channel procedure: in a first step: transmitting (704) a preamble in a first time slot; and transmitting an uplink data transmission via a physical uplink shared channel in a second time slot different from the first time slot; and, in a second step, receiving a response message corresponding to the first step, wherein the response message comprises a radio network temporary identifier.