Carrier Aggregation Control via Unified MAC Commands
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Solution Overview
Problem
Carrier aggregation in LTE systems increases complexity in resource management, particularly in efficiently activating or deactivating component carriers, and requires enhancements in scheduling mechanisms like Buffer Status Report (BSR) and Power Headroom Report (PHR) to manage multiple carriers effectively.
Innovation Solution
A single Logic Channel ID (LCID) value is used to represent both activation and deactivation commands for user equipment, with a bitmap format in MAC control elements for multiple CC management, and novel BSR and PHR procedures are introduced to ensure efficient reporting and linking types are created based on carrier indicator fields for improved scheduling flexibility and load balancing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carrier aggregation is implemented to support bandwidth up to 100 MHz and peak data rates exceeding 1 Gbps, then system throughput and data rates are improved, but resource management complexity increases
Solution Approach 1:
The patent combines multiple component carrier activation/deactivation commands into a single MAC control element. Instead of sending separate commands for each component carrier, the eNB packs activation/deactivation instructions for multiple carriers into one unified message, reducing signaling overhead and simplifying resource management while maintaining the ability to manage multiple carriers for high throughput
Solution Approach 2:
The MAC control element is designed with a universal bitmap structure that can represent activation or deactivation states for multiple component carriers simultaneously. This multi-functional command structure allows a single message to perform multiple carrier management operations, addressing both the throughput requirement and the complexity reduction goal
2Productivity
If multiple component carriers are dynamically activated and deactivated to match UE bandwidth requirements, then bandwidth efficiency is improved, but the number of activation/deactivation operations increases
Solution Approach 1:
The patent merges multiple individual activation/deactivation operations into a single consolidated MAC control element transmission. By grouping carrier state changes that occur within the same TTI into one message, the system achieves bandwidth efficiency through dynamic carrier management while minimizing the frequency of separate activation/deactivation operations
Solution Approach 2:
The eNB prepares and transmits a comprehensive activation/deactivation command in advance, covering multiple component carriers simultaneously. This preliminary action approach allows the UE to receive all necessary carrier management instructions in one go, reducing the need for frequent subsequent activation/deactivation operations and improving bandwidth efficiency
3Measurement precision
If separate BSR procedures are implemented for each component carrier, then buffer status tracking precision is improved, but signaling overhead increases
Solution Approach 1:
The patent combines buffer status reporting for multiple component carriers into a single aggregated BSR message. Instead of transmitting separate BSRs for each carrier, the UE consolidates buffer status information across all configured carriers into one reporting instance, maintaining precise buffer tracking while significantly reducing signaling overhead
4Adaptability or versatility
If carrier aggregation with multiple UL CCs is configured, then scheduling flexibility is improved, but DL-UL linking complexity increases
Solution Approach 1:
The patent segments the DL-UL linking mechanism into distinct types: static SIB2 linking for basic carrier associations and dynamic grant-based linking for flexible carrier pairings. This segmentation allows the system to maintain simple static links while adding complexity only where needed for scheduling flexibility, managing the trade-off between adaptability and complexity
Data Source
AI summary
Methods to manage multiple component carriers (CCs) efficiently in a mobile network with carrier aggregation (CA) enabled are proposed. For CC activation/deactivation, a single LCID value is used to represent both activation and deactivation command. A single command with multiple instructions is provided to activate and/or deactivate multiple CCs. In addition, unnecessary re-activation or re-inactivation of a CC is prevented, and explicit feedback for activation/deactivation is considered. For scheduling mechanism, a novel buffer status reporting (BSR) procedure is provided, where only one BSR is calculated after preparing all the transport blocks (TB) within one transmission time interval (TTI). Novel power headroom reporting (PHR) format and trigger are also provided. For DL-UL linking, various linking types are created based on whether there is carrier indicator field (CIF) in DL grant or UL grant. The various linking types are used in different applications to improve scheduling flexibility and load balancing.