Femtocell Reference Signal Pattern Assignment for Interference Reduction
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Solution Overview
Problem
In a multi-cell environment, particularly in LTE networks, femtocells face challenges in channel estimation due to interference from neighboring cells, as the existing reference signal patterns selected for macrocells are not effective for femtocells, leading to difficulties in providing service and managing interference.
Innovation Solution
A method is introduced to assign and manage reference signal patterns using a time division scheme, a frequency division scheme, or a hybrid approach in a multi-cell environment, where a central control unit receives femtocell information, requests and transmits reference signal reuse pattern information to network devices, including femtocells, to minimize interference by optimizing signal distribution based on neighboring cell information and signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the existing reference signal pattern selected for macrocells is applied to femtocells, then the device complexity is reduced, but the channel estimation accuracy deteriorates due to interference from neighboring cells
Solution Approach 1:
The patent applies different reference signal patterns to different cell types (macrocells vs. femtocells) based on their specific characteristics. Femtocells use dedicated reference signal patterns that are optimized for their indoor deployment environment and interference conditions, while macrocells use their own patterns. This local differentiation resolves the contradiction by tailoring the reference signal configuration to the specific operational context of each cell type.
Solution Approach 2:
The patent segments the reference signal patterns into distinct sets for macrocells and femtocells. By dividing the single reference signal pattern space into separate segments (macrocell patterns and femtocell patterns), the system avoids the interference issues that would arise from using macrocell patterns in femtocells, thereby improving channel estimation accuracy without requiring a completely new pattern design.
2Area of stationary object
If multiple femtocells are installed in a building, then the coverage is improved, but the interference between neighboring femtocells increases
Solution Approach 1:
The patent segments the reference signal patterns into different sets that can be assigned to different femtocells. By having multiple distinct reference signal patterns available and assigning them to different femtocells in the building, the system enables frequency division or time division multiplexing, allowing multiple femtocells to operate simultaneously without mutual interference while maintaining comprehensive coverage.
Solution Approach 2:
The patent implements dynamic reference signal pattern assignment where the eNodeB can select and assign appropriate reference signal patterns to femtocells based on real-time interference conditions and traffic demands. This dynamic adaptation allows the system to manage interference between multiple femtocells while maintaining extensive coverage.
3Reliability
If reference signal reuse pattern information is transmitted to multiple network devices, then the interference management is improved, but the signaling overhead increases
Solution Approach 1:
The patent implements preliminary action by having the eNodeB pre-configure and pre-assign reference signal patterns to femtocells before they start operating. The eNodeB maintains a table of assigned patterns and can proactively manage interference by adjusting patterns before conflicts arise, reducing the need for continuous signaling and thereby minimizing overhead while maintaining reliable interference management.
Solution Approach 2:
The patent enables self-service by allowing femtocells to autonomously configure their reference signal patterns based on information received from the eNodeB. The femtocells can independently manage their own interference characteristics by selecting appropriate patterns from predefined sets, reducing the signaling burden on the network while maintaining effective interference management.
Data Source
AI summary
A method of assigning and managing reference signals in a multi-cell environment, and a network device and a terminal for applying the method, are provided. Reference signal patterns may be assigned to multiple femtocells through a long term coordination of a central control unit that is used to control multiple cells.