2-Step Random Access BSR Transmission for Low-Latency NTN Uplink
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Solution Overview
Problem
The long transmission delays in satellite communication networks due to high distances and long round-trip times result in unsatisfactory quality of service for uplink data transmission in non-terrestrial networks (NTN) using existing 4-step random access channels.
Innovation Solution
Implementing a 2-step random access channel (RACH) for buffer status report (BSR) transmission, allowing BSR to be sent on a physical uplink shared channel (PUSCH) during MSGA, and utilizing uplink resources obtained through scheduling requests (SR) to minimize delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If 4-step random access channel is used for uplink data transmission in NTN, then procedure reliability is maintained, but transmission delay increases significantly due to long round-trip times
Solution Approach 1:
The patent segments the random access procedure into two distinct paths: a fast 2-step RACH path for low-latency BSR transmission and a traditional 4-step RACH path for reliable uplink data transmission. This segmentation allows the system to maintain procedure reliability through the 4-step path while reducing transmission delay through the 2-step path for critical BSR messages.
Solution Approach 2:
The patent introduces dynamic selection mechanisms where the terminal determines whether to use 2-step or 4-step RACH based on real-time conditions such as data volume, QoS requirements, and network status. This dynamic adaptation allows the system to optimize between transmission delay and reliability based on current operational needs.
2Loss of time
If 2-step random access channel is used for BSR transmission, then transmission delay is reduced, but resource occupation increases
Solution Approach 1:
The patent applies local quality by differentiating resource allocation for different transmission scenarios. 2-step RACH resources are specifically allocated and configured for BSR transmission with low latency requirements, while 4-step RACH resources are allocated for uplink data transmission. This localized resource allocation optimizes delay performance for BSR without unnecessarily occupying resources for data transmission.
Solution Approach 2:
The patent changes key parameters including message structure (combining BSR with other signals in MSGA), timing parameters (reducing round-trip time to 2 steps), and resource configuration parameters to enable efficient 2-step RACH operation. These parameter changes allow the system to reduce delay while managing resource occupation through optimized configuration.
3Adaptability or versatility
If dynamic selection of transmission method is implemented, then quality of service compliance is improved, but device complexity increases
Solution Approach 1:
The patent implements preliminary action by pre-configuring both 2-step and 4-step RACH procedures with their respective resource allocations and selection criteria before actual transmission occurs. The terminal evaluates conditions (data volume, QoS requirements, network status) and pre-determines the optimal path, reducing the complexity of real-time decision-making during actual transmission.
Data Source
AI summary
A communication apparatus includes: a receiver, which in operation, receives a resource configuration of 2-step random access procedure; a transmitter, which in operation, transmits a message A (MSGA) of the 2-step random access procedure, where the MSGA includes buffer status report (BSR) in a first case.