Base Station Identification via CRC Masking in Hybrid Femto Networks
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Solution Overview
Problem
Current technologies face challenges in distinguishing and managing femto base stations from macro cells and differentiating between open-access and closed-subscriber group (CSG) femto base stations, which affects handover operations and access control in wireless communication systems.
Innovation Solution
The system identifies femto base stations by using cyclic redundancy check (CRC) masks and scrambling sequences applied to broadcast channel communications, allowing mobile stations to determine their access authorization and differentiate between various types of base stations, including open-access and CSG femto base stations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CRC masks and scrambling sequences are applied to broadcast channel communications to identify femto base stations, then access control and handover management are improved, but device complexity and processing overhead increase
Solution Approach 1:
The patent applies CRC masks and scrambling sequences preliminarily to broadcast channel communications before mobile stations attempt access. This preliminary encoding allows mobile stations to identify femto base station types and verify access authorization in advance, improving access control reliability while distributing processing requirements across the communication protocol stack rather than concentrating complexity in single devices.
2Measurement precision
If base station identifiers are extracted from CRC masks or scrambling sequences, then differentiation between open-access and CSG femto base stations is improved, but measurement and detection difficulty increases
Solution Approach 1:
The patent uses CRC masks and scrambling sequences as intermediary elements that carry base station identifier information. Instead of directly transmitting identifiers that would be easily detectable, the system embeds identification data within these intermediary coding structures. Mobile stations extract identifiers by processing the intermediary CRC masks or scrambling sequences, achieving precise base station differentiation while the intermediary layer obscures the direct measurement path.
3Reliability
If hybrid femto base stations use CRC masks applied to broadcast channel CRC, then access authorization determination is improved, but loss of time in processing increases
Solution Approach 1:
The patent applies CRC masks partially to specific broadcast channel communications rather than all communications. By selectively applying CRC masking to broadcast channels that carry access authorization information, the system improves access authorization reliability for critical messages while avoiding excessive processing time that would result from applying the same mechanism to all communication types. The partial application focuses computational resources only where needed.
Data Source
AI summary
A system and method for identifying the accessibility of a base station in a communication system. The system includes at least one Closed Subscriber Group (CSG)-Open (hybrid) base station. The base station can apply a base station identifier, such as a CSG identifier, as a cyclic redundancy check (CRC) mask to a first broadcast channel communication and can include the base station identifier in the payload of, or as a CRC mask applied to, a second broadcast channel communication. A mobile station can determine from the base station identifier in the first broadcast communication if the mobile station is a member authorized closed access to the base station. The mobile station can determine from the base station identifier in second first broadcast communication if the mobile station is a non-member authorized open access to the base station.