Carrier Aggregation Control Channel Sharing
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Solution Overview
Problem
In mobile communication systems, existing technologies face challenges in efficiently sharing a control channel across multiple carriers in carrier aggregation, leading to resource allocation difficulties and increased interference levels, which complicates the implementation of Physical Downlink Control Channels (PDCCH) on all carriers.
Innovation Solution
The system allows for the sharing of a single control channel resource, such as a PDCCH region, amongst two or more carriers, using existing DCI control message formats, where CCEs are assigned to different groups and carriers, and carrier identification fields are used to determine resource allocations, enabling efficient resource management without modifying existing DCI formats.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate control channel is allocated to each carrier in carrier aggregation, then resource allocation is simplified and interference is reduced, but control channel resources are insufficient and device complexity increases
Solution Approach 1:
The patent merges control channel resources across multiple carriers by implementing a shared PDCCH region that can allocate control messages to multiple component carriers. This consolidation ensures sufficient control channel resources are available while reducing the complexity of implementing separate control channels on each carrier.
Solution Approach 2:
The control channel is designed with multi-functionality to serve multiple carriers simultaneously. The PDCCH region can dynamically allocate control messages to different component carriers based on traffic needs, making the control channel resource universal across the carrier aggregation scenario.
2Productivity
If control channel resources are shared across multiple carriers, then resource utilization efficiency is improved and device complexity is reduced, but interference levels increase and resource allocation becomes complex
Solution Approach 1:
The shared control channel resources are segmented into different search spaces - common search space and UE-specific search space. This segmentation allows different types of control messages to be organized separately, improving resource utilization efficiency while managing interference through structured allocation.
Solution Approach 2:
The control channel allocation is made dynamic through the introduction of Carrier Indication Field (CIF) that enables flexible carrier identification within DCI messages. This dynamic allocation allows the system to adapt resource distribution based on traffic conditions while maintaining efficient resource utilization and managing interference levels.
3Device complexity
If existing DCI control message formats are used without modification, then implementation complexity is reduced and compatibility is maintained, but carrier identification capability is insufficient
Solution Approach 1:
The Carrier Indication Field (CIF) is preliminarily configured and integrated into the existing DCI message structures. This preliminary action maintains compatibility with existing DCI formats while enabling carrier identification capability, avoiding the need for complex format modifications.
Solution Approach 2:
The CIF acts as an intermediary element within the DCI messages that enables carrier identification without fundamentally changing the existing DCI format structure. This intermediary approach maintains compatibility while adding the necessary adaptability for carrier aggregation scenarios.
Data Source
AI summary
A method for processing a control channel at a user agent (UA) to identify at least one of an uplink and a downlink resource allocated by a resource grant within a multi-carrier communication system wherein resource grants are specified by control channel element (CCE) subset candidates wherein the carriers used for data transmission and reception are configured carriers, the method comprising the steps of receiving activation signals specifying active and deactivated carriers from among the configured carriers, for active carriers (i) identifying a number of CCE subset candidates to decode and (ii) decoding up to the identified number of CCE subset candidates in an attempt to identify the resource grant; and for deactivated carriers, ignoring CCE subset candidates associated with the deactivated carriers.