TBS Alignment for CFRA Random Access Data Loss
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Solution Overview
Problem
In New Radio (NR) systems, when switching from Contention Based Random Access (CBRA) to Contention Free Random Access (CFRA) during a random access procedure, the Transport Block Size (TBS) allocated for uplink data transmission is not consistently matched, leading to potential data loss due to mismatched preamble groups, as the NR NodeB does not know which preamble group was used for the CBRA attempt.
Innovation Solution
The method involves determining a granted TBS for CFRA by associating it with the TBS allocated for the initial CBRA request, ensuring consistent TBS allocation for both CBRA and CFRA requests, thereby avoiding data loss and improving transmission efficiency by using the same TBS for subsequent data blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the network device allocates different TBS for CFRA and CBRA preambles, then the TBS allocation flexibility is improved, but the data transmission reliability deteriorates due to mismatched preamble groups causing data loss
Solution Approach 1:
The patent applies universality by making the TBS allocation rule applicable to both CFRA and CBRA preambles. The network device determines TBS based on the preamble group index, and this determination method works universally for both contention-free and contention-based random access procedures, ensuring consistent behavior across different access types while maintaining data transmission reliability
Solution Approach 2:
The patent uses parameter changes by dynamically adjusting the TBS based on the preamble group index parameter. The network device changes the TBS parameter according to which preamble group (first or second group) is detected, allowing flexible adaptation to different random access scenarios while maintaining reliable data transmission through consistent parameter-based allocation
2Device complexity
If the network device uses a fixed TBS allocation method, then the system complexity is reduced, but the data transmission efficiency deteriorates due to inability to handle different preamble groups appropriately
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the TBS based on the detected preamble group index. Instead of using a fixed TBS allocation, the network device changes the TBS parameter according to whether the first or second preamble group is detected, thereby improving data transmission efficiency without significantly increasing system complexity through a straightforward parameter-based differentiation approach
Solution Approach 2:
The patent applies segmentation by dividing the random access preambles into different groups (first preamble group and second preamble group) with different TBS allocations. This segmentation allows the system to handle different random access scenarios appropriately, improving data transmission efficiency by treating different preamble groups differently while maintaining manageable system complexity
Data Source
AI summary
Embodiments of the present disclosure relate to methods, devices and computer readable storage media for determining a transport block size (TBS) for Contention Free Random Access (CFRA) in a random access procedure. In example embodiments, a CFRA request is transmitted by a terminal device to a network device during a random access procedure. The terminal device receives a random access response to the CFRA request from the network device. The random access response indicates a TBS granted by the network device for use in transmission. Based on the granted TBS, the terminal device transmits, to the network device, a first data block with the granted TBS or a second data block to be transmitted and stored in a buffer. In this way, the data loss may be avoided, and the data transmission efficiency may be improved.