Fallback PDCCH Recovery for Secondary Cell Radio Link Failure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In dual connection and/or carrier aggregation scenarios, radio link failures in secondary cells (SCells) lead to physical downlink control channel (PDCCH) resource congestion on primary cells (PCells), compromising communication reliability.
Innovation Solution
Implementing fallback PRACH resources and CORESETs on PCells or PSCells to enable quick recovery of physical layer control channels by sending random access preambles and receiving PDCCHs, allowing continued data scheduling on PCells or PSCells even when SCells experience radio link failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cross-carrier scheduling is implemented where PCell or PSCell schedules SCell, then scheduling flexibility and spectrum utilization are improved, but radio link failures in SCell cause PDCCH resource congestion on PCell
Solution Approach 1:
The patent segments the control channel resources by introducing separate fallback PDCCH resources on PCell/PSCell that are dedicated to receiving control information when SCell experiences radio link failure. This segmentation isolates the failure impact to specific resources rather than affecting all PDCCH resources on PCell, thus maintaining scheduling flexibility while improving reliability.
Solution Approach 2:
The fallback PDCCH resources act as an intermediary mechanism between the failed SCell and the PCell. When SCell fails, the intermediary fallback resources enable the terminal to still receive control information from PCell, preventing complete communication breakdown and maintaining system reliability without sacrificing scheduling flexibility.
2Speed
If fallback PRACH resources and CORESETs are configured on PCell or PSCell, then radio link recovery speed is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring fallback PRACH resources and CORESETs on PCell/PSCell before actual radio link failure occurs. The network device and terminal both prepare the fallback resources in advance, so when failure happens, the terminal can immediately use these pre-prepared resources for rapid recovery without needing to configure anything at the moment of failure, thus achieving fast recovery with manageable complexity.
3Device complexity
If PDCCH resources are concentrated on PCell for cross-carrier scheduling, then control signal transmission is simplified, but resource congestion occurs during SCell radio link failure
Solution Approach 1:
The patent segments PDCCH resources into normal PDCCH resources for regular scheduling and fallback PDCCH resources for failure recovery scenarios. This segmentation allows the system to maintain simplified control signal transmission during normal operation while ensuring sufficient resource availability during failures, as the fallback resources are specifically allocated for congestion scenarios.
Solution Approach 2:
The fallback PDCCH resources serve as a cushion prepared in advance for congestion scenarios. When SCell fails and PDCCH resources on PCell become congested, the beforehand prepared fallback resources provide an additional buffer that ensures continuous control signal transmission, preventing resource exhaustion and maintaining system functionality.
Data Source
AI summary
A method for radio link monitoring and recovery is performed by a terminal, and includes: sending a random access preamble on a fallback random access chancel resource in response to a radio link failure occurring in a secondary cell; and receiving a first physical downlink control channel (PDCCH) sent on a fallback control resource (CORESET) resource, wherein the first PDCCH is configured to schedule a data channel on one of a primary cell, a primary secondary cell, the secondary cell, or another secondary cell.