SBFD Random Access Occasion Selection for Collision-Aware Retransmission
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Solution Overview
Problem
In wireless communications systems, subband full duplex (SBFD)-aware devices face challenges such as random access collisions, inefficient resource use, and increased latency due to uncoordinated UE selection of random access occasions (ROs), leading to degraded user experience and system performance.
Innovation Solution
Implementing network-controlled RO selection techniques, including probability values and threshold configurations, to guide UEs in selecting between half-duplex and SBFD ROs, thereby optimizing resource use and reducing collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If UEs autonomously select random access occasions without network coordination, then device complexity and operation autonomy are improved, but random access collisions and resource efficiency deteriorate
Solution Approach 1:
The network provides feedback to UEs about the selected RO through downlink control information (DCI), enabling coordinated random access. The network entity monitors UE selections and provides guidance signals that reduce collisions while maintaining UE autonomy in the final selection decision.
Solution Approach 2:
The network entity acts as an intermediary that coordinates between multiple UEs and the random access resources. By providing control signaling that indicates preferred ROs, the network mediates the selection process to reduce collisions without completely removing UE autonomy.
2Adaptability or versatility
If multiple ROs are provided for half-duplex and SBFD modes, then adaptability to different duplex modes is improved, but device complexity and configuration complexity increase
Solution Approach 1:
The random access occasions are segmented into different sets corresponding to different duplex modes (half-duplex and SBFD). Each set is configured with specific parameters, allowing UEs to select the appropriate set based on their operational mode while simplifying the overall management through clear separation.
Solution Approach 2:
The system dynamically selects between different RO sets based on the duplex mode. The network can indicate which RO set to use through control signaling, allowing flexible adaptation between half-duplex and SBFD operations without requiring UEs to manage all configurations simultaneously.
3Productivity
If network-controlled RO selection is implemented, then resource efficiency and collision reduction are improved, but system latency and control signaling overhead increase
Solution Approach 1:
The network pre-configures multiple RO sets for different duplex modes before random access occurs. This preliminary configuration reduces the need for real-time control signaling during the actual random access procedure, thereby reducing latency while maintaining resource efficiency.
Solution Approach 2:
The system changes parameters such as the RO set index based on duplex mode through control signaling. By optimizing which parameters are signaled and when, the system achieves good resource utilization while minimizing the timing impact of control overhead.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A network entity may indicate, to a user equipment (UE), a probability value indicating a likelihood that the UE will select a subband full duplex (SBFD) random access occasion (RO) (e.g., instead of a non-SBFD RO) for an initial random access transmission. In case of random access failure, the UE may select another RO and retransmit a random access preamble. In some examples, the network may also configure one or more additional probability values for subsequent retransmissions. In some examples, the network entity may also provide one or more threshold values providing constraints for switching between types of ROs. The UE may transmit capability information to the network entity indicating its capability to switch between ROs of different types, quantities of times the UE is capable of switching or quantities of transmissions the UE supports before switching.