Cross-Cell Scheduling Collision Avoidance in TDD Carrier Aggregation
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Solution Overview
Problem
In a time division duplex (TDD) wireless access system supporting carrier aggregation, there are challenges in smoothly transmitting and receiving reference signals and scheduling data transmission times across component carriers with different uplink-downlink configurations, leading to potential collisions during cross carrier scheduling.
Innovation Solution
The method involves configuring cell groups with the same uplink-downlink configuration for user equipment, performing cross cell scheduling between cells, checking for collision subframes, and adjusting the transmission position of uplink or downlink data to prevent collisions, thereby enabling smooth data transmission and reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cross carrier scheduling is performed between component carriers with different uplink-downlink configurations, then transmission capacity is increased, but collision between downlink of one component carrier and uplink of another component carrier occurs
Solution Approach 1:
The patent segments component carriers into different cell groups based on their uplink-downlink configurations. Each cell group contains component carriers with the same TDD configuration, preventing collisions within groups while allowing cross-group scheduling with proper collision detection and resolution mechanisms.
Solution Approach 2:
The patent introduces a scheduling mechanism that acts as an intermediary between cell groups with different configurations. The base station performs cross-carrier scheduling by selecting appropriate transmission positions that avoid collision, effectively mediating between the conflicting uplink and downlink requirements of different component carriers.
2Speed
If multiple component carriers are aggregated to support wideband, then data transmission rate is increased, but scheduling complexity increases due to different uplink-downlink configurations
Solution Approach 1:
The patent divides the aggregated component carriers into multiple cell groups, where each group shares the same TDD configuration. This segmentation reduces scheduling complexity by allowing independent scheduling within each group while managing inter-group scheduling separately, thus handling the complexity of multiple carriers with different configurations.
Solution Approach 2:
The patent changes the scheduling parameter by introducing cell group identifiers and configuration-based grouping. Instead of scheduling each component carrier individually, the system schedules at the cell group level, reducing the number of scheduling decisions and simplifying the overall scheduling complexity while maintaining high data transmission rates.
3Reliability
If cell groups are configured with the same uplink-downlink configuration, then collision is avoided, but flexibility in resource allocation is reduced
Solution Approach 1:
The patent segments component carriers into cell groups with identical TDD configurations to ensure reliable collision-free operation within each group. Simultaneously, it maintains adaptability by allowing multiple cell groups with different configurations to coexist, enabling the system to adapt to diverse traffic requirements while preserving reliability through intra-group consistency.
Solution Approach 2:
The patent creates a universal scheduling framework that can handle both intra-group scheduling (with same configuration for reliability) and inter-group scheduling (with different configurations for flexibility). This multi-functional approach allows the system to maintain collision avoidance within groups while providing adaptable resource allocation across the entire aggregated bandwidth.
Data Source
AI summary
In the present invention, a method for transmitting/receiving data in a wireless access system and a base station for same are disclosed. More particularly, the method comprises the following steps: setting a cell group per at least one cell having an identical uplink-downlink configuration, if a plurality of cells are set to a user equipment; performing via a first cell cross-cell scheduling with regard to a second cell, which belongs to a cell group that is different from that including the first cell, according to the uplink-downlink configuration of the first cell; confirming the occurrence of a collision subframe, in which an uplink subframe and a downlink subframe exist simultaneously in the same time interval, in two cells performing the cross-cell scheduling; and transmitting/receiving data with the user equipment when scheduled in the collision subframe due to the cross-cell scheduling, by modifying a transmission position of the uplink or the downlink according to the cross-cell scheduling.