Cross-Carrier Indicator Field for LTE Scheduling Overhead
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Solution Overview
Problem
Current LTE wireless communication systems face challenges in efficiently scheduling transmissions across multiple carriers and subframes, particularly in heterogeneous networks, where cross-carrier and cross-subframe indications are not effectively managed, leading to increased overhead and interference.
Innovation Solution
The implementation of a cross-subframe/cross-carrier indicator field (xSF/CIF) in the physical downlink control channel (PDCCH) allows for dynamic mapping of control information across different subframes and component carriers, enabling simultaneous scheduling of transmissions and resource partitioning to mitigate interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cross-carrier PDCCH indication is implemented with carrier index bits, then scheduling flexibility across carriers is improved, but PDCCH overhead increases
Solution Approach 1:
The patent extracts the carrier indication function from the traditional PDCCH carrier index bits and relocates it to a separate cross-carrier indicator field (CIF) in the downlink control information (DCI). This separation allows the PDCCH to maintain its original scheduling function while the CIF handles carrier identification, reducing PDCCH overhead while preserving scheduling flexibility across multiple carriers.
Solution Approach 2:
The cross-carrier indicator field (CIF) acts as an intermediary between the PDCCH and the scheduled transmission on different carriers. Instead of embedding carrier information directly in the PDCCH, the CIF mediates the connection by carrying the carrier index that links the control information to the appropriate data transmission carrier, thus reducing overhead while maintaining adaptability.
2Adaptability or versatility
If control information is transmitted on each component carrier, then carrier-specific scheduling is improved, but control signaling overhead increases
Solution Approach 1:
The patent implements a universal cross-carrier indicator field (CIF) that can indicate multiple different component carriers using the same field structure. This multi-functional approach allows a single CIF design to serve all carrier indication needs across different carriers, enabling carrier-specific scheduling without requiring separate control signaling mechanisms for each carrier, thus reducing overall control signaling overhead.
3Device complexity
If carrier aggregation is implemented without cross-carrier indication, then system complexity is reduced, but interference management capability deteriorates
Solution Approach 1:
The patent segments the control information structure by separating the carrier indication function into a distinct cross-carrier indicator field (CIF) within the downlink control information. This segmentation allows the system to manage multiple carriers with differentiated interference conditions by providing specific carrier indicators, enabling targeted interference management for each carrier while maintaining overall system structure and avoiding excessive complexity.
Data Source
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AI summary
Techniques for cross-subframe and cross-carrier scheduling of uplink and downlink transmissions in a multi-carrier wireless communication system are disclosed. A base station can include cross-subframe, carrier indication (xSF/CIF) information in a PDCCH message to signal to a user equipment (UE) which subframes and/or component carriers pertain to control information carried therein. The UE may utilize the xSF/CIF information to determine to which subframes and/or component carriers the control information is to be applied.