Carrier Aggregation Sensing via Empty PDCCH Fields
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Solution Overview
Problem
In carrier aggregation scenarios, especially when deploying LTE on unlicensed bands, there is a challenge in reliably sensing and reporting interference on downlink component carriers to ensure uninterrupted control/scheduling information transmission, particularly due to varying interference situations from different component carriers and unknown systems operating in the same unlicensed spectrum.
Innovation Solution
The method involves configuring user equipment (UE) to perform sensing on empty PDCCH fields of downlink component carriers operating on shared spectrum, using existing signaling mechanisms to derive sensing duration and resources, and reporting feedback through PUCCH, thereby reducing additional signaling overhead and enabling reliable interference measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If carrier aggregation is deployed on unlicensed bands, then more spectrum resources are available, but interference management becomes more complex and unreliable
Solution Approach 1:
The system performs preliminary sensing on empty PDCCH fields before actual data transmission to detect potential interference from unknown systems. This advance detection allows the network to identify interferers and adjust scheduling decisions proactively, ensuring reliable control information transmission despite the unlicensed band environment.
Solution Approach 2:
The UE provides feedback reports about sensed interference conditions on secondary component carriers. This feedback mechanism enables the eNB to continuously monitor the interference environment and dynamically adjust cross-carrier scheduling decisions, maintaining reliable interference management across aggregated carriers in unlicensed spectrum.
2Measurement precision
If sensing is performed on all component carriers, then interference detection is comprehensive, but signaling overhead increases
Solution Approach 1:
Instead of uniform sensing across all carriers, the system applies sensing selectively based on local conditions. Cross-carrier scheduling is employed where a primary component carrier carries control information for multiple secondary carriers, allowing the UE to sense and report interference on secondary carriers without requiring separate PDCCH resources on each carrier. This localized approach maintains detection precision while reducing overall signaling overhead.
3Adaptability or versatility
If control information is transmitted on each component carrier, then scheduling flexibility is improved, but vulnerability to interference increases
Solution Approach 1:
The primary component carrier acts as an intermediary that centralizes control information transmission. Instead of each secondary carrier having its own independent PDCCH, the eNB schedules resources on secondary carriers via cross-carrier scheduling commands transmitted on the primary carrier's PDCCH. This intermediary approach consolidates control signaling, reducing the number of control channels exposed to interference while preserving scheduling flexibility across all aggregated carriers.
Data Source
AI summary
The present invention proposes methods, devices and computer program products in relation to a communication module configured for communication in a carrier aggregation mode aggregating a primary and at least one secondary carrier. Scheduling information is carried in a control channel of one of the carriers, the scheduling information being associated to a respective one of said aggregated carriers and designating search spaces for payload in a payload channel of said respective aggregated carrier. Sensing is performed responsive to a sensing command added to the scheduling information associated to said at least one secondary carrier, which sensing command commands sensing to be performed on said at least one secondary carrier.