CFI Determination via RRC Signaling in MBSFN Subframes
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Solution Overview
Problem
In wireless communication systems, determining the Control Format Indicator (CFI) value is inefficient, especially in Multi-Media Broadcast over a Single Frequency Network (MBSFN) configurations, leading to increased overhead and coordination requirements among eNBs due to frequent reconfigurations and signaling needs.
Innovation Solution
Configuring system devices with multiple component carriers for carrier aggregation, receiving PDSCH on a first component carrier, transmitting a corresponding PDCCH on a second component carrier, and using a RRC signal to set an initial CFI value that determines the starting point of PDSCH, with specific settings for MBSFN subframes to reduce resource waste and simplify CFI determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If CFI is signaled for every subframe, then the starting point of PDSCH can be determined, but overhead increases
Solution Approach 1:
The patent extracts the CFI determination from frequent subframe-by-subframe signaling and moves it to less frequent RRC signaling, taking out only the essential initial CFI configuration while allowing UE to autonomously determine subsequent CFI values based on subframe type and MBSFN configuration
Solution Approach 2:
The UE is enabled to self-determine CFI values for different subframe types based on pre-configured RRC parameters and detected subframe characteristics, eliminating the need for continuous network signaling and allowing the system to serve itself without external intervention
2Adaptability or versatility
If MBSFN subframe configuration changes frequently, then service flexibility is improved, but reconfiguration overhead increases
Solution Approach 1:
The patent applies preliminary action by configuring UE with multiple CFI values corresponding to different MBSFN subframe configurations through RRC signaling in advance. When MBSFN configuration changes, the network can simply indicate which pre-configured CFI value to use rather than reconfiguring all parameters, significantly reducing reconfiguration overhead
Solution Approach 2:
The patent utilizes parameter changes by introducing an initial CFI configuration parameter through RRC signaling that remains valid across MBSFN configuration changes. The UE determines actual CFI based on this initial parameter combined with current subframe type, allowing flexible adaptation without frequent reconfiguration
3Ease of operation
If CFI information is maintained for each eNB, then local control is improved, but coordination complexity increases
Solution Approach 1:
The patent segments the CFI control into cell-specific initial configuration (via RRC) and subframe-specific determination (via UE autonomous detection). Each eNB independently configures its own cell-specific CFI parameters without needing to coordinate with other eNBs, while the UE handles the coordination of determining appropriate CFI values across different subframe types
Data Source
AI summary
A method and apparatus are disclosed determine a CFI value in a wireless communication system. In one embodiment, the method comprises configuring system devices, such as a UE or an eNB, with a plurality of component carriers for carrier aggregation. Furthermore, the method comprises receiving PDSCH on a first component carrier. The method also comprises transmitting a corresponding PDCCH on a second component carrier. In addition, the method comprises using a RRC signal to configure a CFI with an initial configured value. The method further comprises setting the CFI so that the CFI could be used to determine a starting point of the PDSCH.