Femto Base Station Handover via BS-ID Mapping
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Solution Overview
Problem
The existing broadband wireless communication systems face limitations in supporting handover due to the restricted number of Base Station Identifiers (BS-IDs) in neighbor lists, particularly in scenarios with densely located femto/pico base stations, which hinders smooth handover operations and efficient air/MAC configuration management.
Innovation Solution
The method involves configuring and transmitting mapping information related to BS-IDs and power levels from macro base stations to sub base stations, allowing for controlled handover and efficient air/MAC configuration management, even when multiple base stations share the same BS-ID, by managing frequency bands, TX power, DCD CCCs, and UCD CCCs, and utilizing Self Organization Network (SON) parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of neighbor lists is increased to support more base stations, then handover capability is improved, but the limitation of 255 neighbor lists per base station cannot be overcome
Solution Approach 1:
The patent divides the base station identification system into two parts: a common BS-ID shared by multiple base stations and a cell-specific identifier (CID or C-RNTI) that distinguishes individual cells. This segmentation allows multiple base stations to be identified within the existing 255 neighbor list limit by using different cell identifiers rather than requiring unique BS-IDs for each base station.
Solution Approach 2:
The patent introduces an intermediary mapping mechanism that translates between the limited BS-IDs in the neighbor list and the actual large number of base stations. The mapping information stored in the base station associates BS-IDs with multiple cell identifiers, enabling the system to indirectly reference more base stations than the neighbor list can directly hold.
2Measurement precision
If all base stations use unique Base Station Identifiers (BS-IDs), then identification accuracy is improved, but the number of available BS-IDs is limited to 255
Solution Approach 1:
The identification system is segmented into a shared BS-ID component and a cell-specific identifier component. The BS-ID provides coarse-grained identification that can be reused across multiple base stations, while the cell identifier (CID/C-RNTI) provides fine-grained differentiation. This segmentation allows the system to maintain identification accuracy for individual cells while overcoming the 255 BS-ID limit.
Solution Approach 2:
Different parts of the identification system serve different purposes: the BS-ID provides local quality of shared identification for neighbor list compatibility, while the cell identifier provides local quality of unique cell differentiation. This local quality approach allows each identifier type to optimize for its specific function rather than requiring all identifiers to be globally unique.
3Ease of operation
If mapping information is configured and transmitted from macro base station to sub base stations, then handover control is improved, but system complexity increases
Solution Approach 1:
The mapping information is pre-configured and stored in the base station before handover operations are needed. This preliminary action allows the base station to quickly perform lookups during handover without real-time computation, reducing the operational complexity during actual handover execution while maintaining good handover control.
Solution Approach 2:
The base station autonomously manages its own mapping information between BS-IDs and cell identifiers without requiring external coordination during handover operations. This self-service approach simplifies the system architecture by eliminating the need for complex centralized management systems while maintaining effective handover control.
Data Source
AI summary
A method and an apparatus for supporting a handover in a broadband wireless access communication system are provided. The method includes configuring mapping information based on information related to base station IDs (BS-IDs) and power used in a plurality of sub base station, and transmitting the mapping information to the plurality of femto base stations, and when a handover request is received from a terminal, performing a handover to one of the plurality of femto base stations is set as a target base station.