BSR Trigger Cancellation in 5G Dual Connectivity
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Solution Overview
Problem
In 5G wireless communication systems, the efficient reporting and cancellation of Buffer Status Reports (BSRs) and Scheduling Requests (SRs) across different Radio Access Technologies (RATs) like LTE and NR are challenging, leading to potential resource misallocation and inefficiencies due to differing cancellation policies and inter-dependent BSR/SR triggers.
Innovation Solution
A user equipment (UE) with dual connectivity to LTE and NR base stations implements a BSR trigger cancellation mechanism that selects a cancellation policy based on the RAT type and bearer type, ensuring that only BSRs with comprehensive buffer status information are cancelled, and corresponding SRs are stopped, thereby aligning BSR and SR cancellation procedures to prevent resource wastage and ensure accurate reporting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If different BSR cancellation policies are applied for different RAT types (LTE and NR), then each RAT can be optimized independently, but complexity increases due to managing multiple policies and inter-dependent triggers across dual connectivity
Solution Approach 1:
The patent implements dynamic BSR cancellation by checking whether all triggered BSRs have been transmitted before cancelling triggers. The MAC entity monitors the transmission status of BSRs and only cancels triggers when confirmation is received that all BSRs containing buffer status information have been successfully transmitted, adapting the cancellation timing based on actual transmission outcomes rather than using fixed cancellation rules
Solution Approach 2:
The patent introduces feedback mechanisms where the MAC entity tracks and monitors the transmission status of BSRs. The cancellation decision is based on feedback information about whether BSRs have been successfully transmitted, creating a closed-loop control system that adjusts cancellation behavior based on actual system state and transmission outcomes
2Speed
If BSR triggers are cancelled immediately upon MAC PDU assembly, then resource allocation is faster, but accuracy decreases because buffer status may change before transmission
Solution Approach 1:
The patent performs preliminary checks before BSR trigger cancellation by verifying whether all triggered BSRs have been transmitted. This preliminary verification action ensures that cancellation only occurs when it is safe to do so, preventing premature cancellation that would lose buffer status information while still enabling timely cancellation when conditions are met
3Measurement precision
If comprehensive buffer status information is ensured in BSR MAC CE, then reporting accuracy is improved, but resource allocation efficiency decreases due to potential over-allocation
Solution Approach 1:
The patent dynamically changes the buffer status reporting parameters by selecting between short and long BSR formats based on the actual number of LCGs with data. This parameter adaptation allows the system to use compact short BSR formats when few LCGs have data (improving efficiency) while switching to comprehensive long BSR formats when more LCGs have data (ensuring accuracy), thus optimizing the trade-off between reporting accuracy and resource efficiency
Data Source
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Figure 3A~3B
AI summary
Embodiments herein provide a method for buffer status reporting. The method includes triggering a buffer status report (BSR) in a media access control (MAC) layer, based on a BSR triggering condition; transmitting, to a base station, a scheduling request (SR) for transmitting uplink data; receiving an uplink resource allocation grant (UL grant) from the base station, based on the SR; assembling a media access control protocol data unit (MAC PDU); transmitting the MAC PDU; and determining whether to cancel the triggered BSR, based on a BSR MAC control element (BSR MAC CE) included in the MAC PDU.