RLC Acknowledged Mode Window Synchronization for Multicast Bearer
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Solution Overview
Problem
Current wireless communication systems, particularly in New Radio (NR) and LTE, face challenges in efficiently managing multicast or broadcast services, leading to increased latency and reduced reliability due to the lack of movement of the RLC acknowledged mode window and inefficient packet delivery mechanisms.
Innovation Solution
The implementation of a method that allows user equipment (UE) to adjust the RLC acknowledged mode transmission window and reception window in synchronization with the base station, enabling in-sequence or out-of-sequence packet delivery and adaptive status reporting to improve packet retransmission and reduce latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multicast or broadcast services are delivered using traditional RLC unacknowledged mode, then network load is reduced, but reliability and packet delivery assurance deteriorate
Solution Approach 1:
The patent implements dynamic RLC window adjustment where the transmission and reception windows are no longer fixed but adaptively move based on packet delivery status. The base station and UE synchronize window positions through status reports, allowing the window to dynamically advance as packets are successfully delivered, thereby providing reliable multicast/broadcast service while maintaining manageable complexity through automated synchronization mechanisms.
2Loss of time
If RLC acknowledged mode is implemented with fixed transmission window, then implementation is simplified, but latency increases due to lack of window movement
Solution Approach 1:
The patent introduces feedback mechanisms where UEs send status reports to the base station indicating which packets have been successfully received. The base station uses this feedback to determine when to advance the transmission window and notifies UEs of the window adjustment. This feedback loop enables automatic window movement that reduces latency while maintaining synchronization without requiring complex manual coordination.
Solution Approach 2:
The patent implements preliminary window adjustment notifications where the base station informs UEs of upcoming window adjustments before they take effect. This allows UEs to prepare their reception windows in advance, ensuring smooth synchronization and preventing packet loss during window transitions, thereby reducing latency while maintaining operational simplicity.
3Reliability
If status reporting is implemented for all UEs, then packet delivery reliability is improved, but network load and signaling overhead increase
Solution Approach 1:
The patent implements selective status reporting where not all UEs are required to send status reports in every transmission cycle. Instead, the base station can configure UEs to report only when necessary (e.g., when packet loss is detected or at specific intervals), providing sufficient reliability information while significantly reducing signaling overhead compared to mandatory reporting from all UEs.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive a configuration for a multicast or broadcast radio bearer (MRB) in a radio link control (RLC) acknowledged mode (AM). The UE may determine an adjustment of an RLC AM transmission window of a base station. The RLC AM transmission window may be associated with retransmission of RLC packets associated with the MRB. The UE may synchronize an RLC AM reception window of the UE with the RLC AM transmission window based at least in part on determining the adjustment of the RLC AM transmission window of the base station. The RLC AM reception window may be associated with reassembly of RLC packets associated with the MRB. Numerous other aspects are provided.