PDCCH Format Adaptation for Cross-Carrier Scheduling Transitions
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communication systems, particularly in LTE-Advanced, the transition between cross carrier scheduling and non-cross carrier scheduling for user equipment (UE) is challenging due to differences in downlink control channel formats, leading to ambiguity for the UE and eNB regarding the use of carrier indicator fields, which affects resource allocation and scheduling efficiency.
Innovation Solution
The solution involves changing the format of the downlink control channel for the UE between cross carrier scheduling and non-cross carrier scheduling, either implicitly or explicitly, based on Connection Reconfiguration messages, ensuring the UE uses the appropriate format for its configured set of component carriers, thereby eliminating the need to decode multiple formats simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the downlink control channel format is changed when switching between cross carrier scheduling and non-cross carrier scheduling, then the UE can correctly interpret carrier indicator fields and avoid ambiguity, but the system complexity increases due to format switching management
Solution Approach 1:
The patent applies dynamics by making the PDCCH format adaptable and changeable based on the scheduling mode. The system dynamically switches between format 0 (without CIF) and format 1b (with CIF) depending on whether cross-carrier scheduling is enabled, allowing the control channel structure to flexibly respond to different operational requirements rather than being fixed.
Solution Approach 2:
The patent changes the parameter of PDCCH format (specifically the inclusion of CIF field) based on the scheduling configuration. When cross-carrier scheduling is enabled, the system transitions to a format that includes the 3-bit CIF field; when disabled, it uses a format without CIF. This parameter change resolves the ambiguity in carrier indicator interpretation.
2Adaptability or versatility
If multiple PDCCH formats are supported simultaneously, then the system can handle both cross carrier and non-cross carrier scheduling, but the UE complexity increases due to the need to decode multiple formats
Solution Approach 1:
The patent implements a dynamic format selection mechanism where the UE is configured to use a single PDCCH format at any given time based on the cross-carrier scheduling configuration. The system transitions between formats rather than maintaining multiple simultaneous formats, reducing UE decoding complexity while preserving adaptability to different scheduling modes through configuration changes.
3Adaptability or versatility
If cross carrier scheduling is enabled, then resource allocation flexibility improves, but the ambiguity in carrier indicator field usage increases
Solution Approach 1:
The patent resolves the carrier indicator field ambiguity by changing the PDCCH format parameter to include a 3-bit CIF field when cross-carrier scheduling is enabled. This explicit CIF field clearly indicates which component carrier is being scheduled, eliminating the ambiguity that would otherwise exist in the carrier indicator interpretation and allowing flexible cross-carrier resource allocation.
Data Source
AI summary
Format of a downlink control channel for a user equipment UE is changed in conjunction with switching the UE between being enabled for cross carrier scheduling and being disabled for cross carrier scheduling. The changed format is used on at least one serving cell of the UE's configured set of component carriers CCs. In one embodiment the changed format comprises an explicit carrier indicator field CIF for the case in which the switching is from disabled to enabled; and the changed format has no explicit CIF when the switching is from enabled to disabled. In another embodiment switching from disabled to enabled comprises the UE's configured set of CCs being changed from one to multiple cells; and switching from enabled to disabled comprises the UE's configured set of CCs being changed from multiple cells to one cell. In one embodiment the changed format is implicit.