Extended Serving Cell Indexing for Carrier Aggregation
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Solution Overview
Problem
Current LTE systems face limitations in carrier aggregation, specifically in serving cell indexing and activation/deactivation functions, which restrict the number of component carriers that can be aggregated to 32, leading to capacity issues and inefficiencies in managing bandwidth for high data rate requirements.
Innovation Solution
The implementation of extended serving cell indexing and medium access control (MAC) control elements that allow for up to 31 secondary serving cells, using new identification values and cell group indexing, along with variable-sized MAC control elements for efficient activation/deactivation and power headroom reporting, to manage and configure a larger number of component carriers dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If current LTE systems use standard serving cell indexing, then the number of component carriers that can be aggregated is limited to 32, but this limitation causes capacity issues and inefficiencies in managing bandwidth for high data rate requirements
Solution Approach 1:
The patent segments the serving cell indexing into two parts: a cell group ID (identifying one of up to 5 cell groups) and a serving cell index within that group (identifying one of up to 7 cells per group). This segmentation allows the system to address up to 35 serving cells (5 groups × 7 cells/group) instead of being limited to 32, while keeping each indexing component manageable in size (2 bits for group ID, 3 bits for cell index).
Solution Approach 2:
The patent introduces a new dimension to the indexing system by adding the cell group ID as an additional hierarchical level. Instead of using a single 5-bit index (0-31), the system now uses a two-level hierarchy: cell group ID (2 bits) and serving cell index within group (3 bits). This dimensional change enables addressing of 35 cells while maintaining efficient bit representation.
2Adaptability or versatility
If the system supports up to 35 serving cells through extended indexing, then bandwidth management capability is improved, but the complexity of activation/deactivation functions increases
Solution Approach 1:
The activation/deactivation MAC control element is segmented to include both a cell group ID field (2 bits) and a serving cell index field (3 bits), mirroring the segmentation of the serving cell index. This allows the control element to uniquely identify any of the 35 serving cells while maintaining a compact structure. The segmentation enables efficient activation/deactivation signaling without requiring a complete redesign of the MAC control element format.
3Quantity of substance
If variable-sized MAC control elements are used for efficient activation/deactivation, then signaling overhead is reduced, but the complexity of processing and interpreting these elements increases
Solution Approach 1:
The patent uses a compact MAC control element format that includes only the necessary fields (cell group ID: 2 bits, serving cell index: 3 bits, activation/deactivation indicator: 1 bit, and reserved bits) to perform activation/deactivation. This partial action approach provides sufficient functionality for the intended purpose without including unnecessary fields, thereby reducing signaling overhead while keeping the processing complexity manageable through a well-defined, concise format.
Data Source
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AI summary
Systems and methods provide component carrier management in carrier aggregation systems. A medium access control (MAC) protocol data unit (PDU) includes an activation/deactivation MAC subheader and an activation/deactivation MAC control element (CE) and a power headroom report, PHR, MAC control element. A plurality of configured carriers are categorized into at least one cell group. Configured secondary cells (SCells) are activated/deactivated according to the activation/deactivation MAC subheader and the activation/deactivation MAC CE. The extended PHR MAC CE includes one or more octets comprising C-fields, and a variable number of octets comprising respective power headroom values for SCells indicated as active by the C-fileds.