Random Access Preamble Repetition With Unified RAR Window Timing
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Solution Overview
Problem
Existing communication systems face low reliability of random access, particularly in frequency range 2 (FR2) bands, where terminals at the cell edge struggle to achieve target transmission performances and may not access the network.
Innovation Solution
A method involving the transmission of preambles with repetitions on multiple physical random access channel occasions, followed by a defined random access response (RAR) window starting from a specific symbol of a control resource set, to enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If preambles are transmitted with repetitions on multiple physical random access channel occasions, then the reliability of random access is improved, but the signaling overhead and resource consumption increase
Solution Approach 1:
The patent segments the random access procedure by defining distinct RAR window starting points for different preamble transmission scenarios. When preambles are transmitted with repetitions, the RAR window starts from the first RO; when transmitted without repetitions, it starts from the last RO. This segmentation allows optimized resource allocation and reduces signaling overhead for each specific case.
Solution Approach 2:
The patent implements dynamic adjustment of the RAR window starting point based on the transmission mode. The network device dynamically determines whether to start the RAR window from the first RO or last RO depending on whether preamble repetitions are used, allowing flexible resource management that reduces overall signaling overhead while maintaining reliability.
2Productivity
If the RAR window starts from the first symbol of the earliest control resource set, then the terminal can monitor PDCCH efficiently, but the timing synchronization between terminal and network may be ambiguous
Solution Approach 1:
The patent establishes a clear feedback mechanism where the network device determines the RAR window starting point based on the preamble transmission mode, and this determination is implicitly feedback to the terminal through the defined association rules. The terminal can infer the correct timing by knowing whether its preamble was transmitted with repetitions, ensuring both efficient PDCCH monitoring and accurate timing synchronization.
Solution Approach 2:
The patent changes the timing parameter (RAR window start point) based on the transmission mode parameter. When preamble repetitions are used, the RAR window starts from the first RO; when not used, it starts from the last RO. This parameter adjustment resolves the timing synchronization ambiguity while maintaining PDCCH monitoring efficiency.
3Reliability
If multiple RAR windows are defined for preamble repetitions, then the network can respond to each transmission occasion, but the device complexity and processing overhead increase
Solution Approach 1:
The patent merges multiple potential RAR windows into a single unified RAR window that starts from the first RO when preamble repetitions are used. Instead of managing separate RAR windows for each transmission occasion, the network and terminal agree on a single window that covers all necessary responses, reducing device complexity while maintaining response reliability.
Solution Approach 2:
The unified RAR window serves multiple functions: it responds to all preamble repetition transmissions, provides a single monitoring opportunity for the terminal, and simplifies network device processing. This multi-functional approach reduces complexity while maintaining the ability to respond reliably to each transmission occasion.
Data Source
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AI summary
Disclosed are a random access processing method and apparatus, a terminal, a network-side device, and a storage medium, belonging to the technical field of communication. The random access processing method includes: A terminal transmits a preamble with repetitions on a plurality of ROs, where the preamble is used for random access. The terminal starts an RAR window, and monitors RAR information. The RAR window starts from a first symbol of an earliest control resource set associated with a first PDCCH, and the first PDCCH is a PDCCH in a Type 1-physical downlink control channel (Type1-PDCCH) common resource set. The RAR window satisfies at least one of the following: The RAR window is at least one symbol following a last symbol of a first RO occupied by the preamble with repetitions. The RAR window is at least one symbol following a last symbol of a last RO occupied by the preamble with repetitions. The RAR window is at least one symbol following a last symbol of each RO occupied by the preamble with repetitions.