D2D Buffer Status Reporting During Radio Link Failure Recovery
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Solution Overview
Problem
In device-to-device (D2D) communication, existing methods fail to effectively handle buffer state reports (BSRs) when a radio link failure (RLF) occurs, leading to inefficiencies in resource allocation and system performance.
Innovation Solution
A method and apparatus for managing BSRs in D2D communication, involving establishing an RRC connection, determining RLF, canceling all BSRs for D2D data transmission, and initializing a re-establishment process, including a timer for BSR, to handle exceptional cases and improve system efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a UE autonomously selects resources for D2D communication instead of using base station allocated resources, then network load is reduced and communication flexibility is improved, but buffer state report handling becomes uncertain and resource allocation efficiency deteriorates
Solution Approach 1:
The patent introduces a new parameter 'autonomous resource selection mode' that changes the operational state of the UE from network-scheduled mode to autonomous mode. In this new parameter state, the UE independently selects resources for D2D communication, which fundamentally alters how buffer state reports are handled and enables the UE to operate without continuous base station coordination, thereby reducing network load while maintaining reliable BSR handling through predefined protocols
2Measurement precision
If buffer state reports are continuously triggered for D2D data transmission, then resource allocation accuracy is improved, but system complexity increases and processing overhead worsens
Solution Approach 1:
The patent implements periodic action by introducing a timer mechanism that controls BSR triggering. Instead of continuously triggering BSRs, the system uses periodic checks where the BSR is triggered only when specific conditions are met within a defined time window. This periodic approach maintains accurate buffer status measurement while significantly reducing the complexity of continuous monitoring and reporting
Solution Approach 2:
The patent applies preliminary action by pre-configuring the timer value and BSR triggering conditions before D2D communication begins. The timer is initialized with a predetermined value, and the UE is pre-instructed on when to trigger BSRs based on buffer status changes. This preliminary setup eliminates the need for complex real-time decision-making during communication, reducing processing overhead while maintaining measurement accuracy
3Ease of operation
If base station schedules all D2D data transmission resources, then resource allocation control is improved, but network dependency increases and system autonomy deteriorates
Solution Approach 1:
The patent implements dynamics by allowing the system to transition between two operational states: network-scheduled mode and autonomous resource selection mode. The UE can dynamically switch between these modes based on communication needs and network conditions. In autonomous mode, the UE independently selects resources without base station scheduling, while in network-scheduled mode, the base station maintains control. This dynamic flexibility maintains ease of operation through controlled transitions while significantly improving UE autonomous communication capability
Data Source
AI summary
A method of supporting a buffer status report (BSR) associated with a device-to-device (D2D) communication includes: establishing a radio resource control (RRC) connection with an evolved NodeB (eNB) and receiving configuration information associated with a D2D communication from the eNB, the configuration information including information of a resource allocation mode for a D2D data transmission and information of a timer associated with a BSR for a D2D data transmission; determining, by a user equipment (UE), a radio link failure (RLF), the RLF being associated with a connection problem of the RRC connection; initializing a re-establishment process for the RRC connection; canceling all BSRs for a D2D data transmission in response to the determined RLF, the canceled BSRs for a D2D data transmission being associated with a D2D data transmission scheduled by the eNB; and initializing the timer associated with a BSR for a D2D data transmission.