FDD Guard Zone Separates Conflicting TDD Coverage Areas
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Solution Overview
Problem
Interference occurs between adjacent cellular access nodes operating on the same TDD carrier with different TDD configurations, leading to overlapping coverage areas during concurrent downlink and uplink communications.
Innovation Solution
Implementing a guard zone of FDD coverage between the conflicting TDD coverage areas by configuring one access node to provide FDD service to cell-edge UEs and restricting TDD service to cell-center UEs, creating a spatial buffer between the TDD coverage areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If adjacent access nodes use different TDD configurations on the same carrier, then service flexibility and adaptability are improved, but interference between coverage areas increases
Solution Approach 1:
The coverage area is segmented into cell-center and cell-edge zones. Cell-center UEs are served by TDD carrier while cell-edge UEs are served by FDD carrier. This spatial segmentation allows different TDD configurations to coexist without interference by isolating them geographically.
Solution Approach 2:
An FDD carrier is introduced as an intermediary between conflicting TDD carriers. The FDD coverage acts as a buffer zone that mediates between adjacent TDD coverage areas with different configurations, preventing direct interference while maintaining service continuity.
2Area of stationary object
If TDD coverage areas are expanded to serve more UEs, then service coverage is improved, but interference with adjacent TDD carriers increases
Solution Approach 1:
The solution transitions from a single-carrier TDD system to a multi-carrier system incorporating both TDD and FDD dimensions. By adding the FDD dimension, the system can provide extended coverage to cell-edge UEs without the interference constraints that limit TDD coverage expansion.
Solution Approach 2:
Coverage is segmented across multiple carriers: TDD carrier handles cell-center coverage while FDD carrier handles cell-edge coverage. This allows each carrier to be optimized for its specific coverage zone without causing interference to adjacent cells.
3Object-affected harmful factors
If FDD coverage is used to create a guard zone, then interference between TDD carriers is reduced, but device complexity increases
Solution Approach 1:
Different carrier types are assigned to different spatial locations: TDD carriers serve cell-center regions while FDD carriers serve cell-edge regions. This local differentiation allows interference reduction through strategic carrier placement without requiring complex system-wide changes.
Solution Approach 2:
The system automatically selects appropriate carriers for different UE locations based on predefined criteria. Cell-center UEs are automatically assigned to TDD carriers while cell-edge UEs are assigned to FDD carriers, reducing the need for complex manual configuration and management.
Data Source
AI summary
In a system where a first node provides a first area of TDD coverage on a first TDD carrier using a first TDD configuration and an adjacent second node provides a second area of TDD coverage on a second TDD carrier using a different second TDD configuration, the first node could additionally provide an area of FDD coverage on a first FDD carrier, including causing the area of FDD coverage to sit at least partially between the first and second areas of TDD coverage and therefore to define a spatial buffer between the first and second areas of TDD coverage. For instance, the first access node could restrict its service on the first TDD carrier to be for user equipment devices (UEs) that are relatively close to the first access node and could restrict its service on the first FDD carrier to be for UEs that are relatively far away from the first access node.