Femtocell Dual Scrambling Code Selection via Geolocation
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Solution Overview
Problem
Current networking architectures face challenges in integrating femtocells into macro networks for seamless hand-in and hand-out scenarios, particularly in large-scale deployments where traditional methods are inflexible and limited by the number of scrambling codes that can be broadcast, leading to difficulties in selecting the appropriate femtocell for user connectivity.
Innovation Solution
The implementation of a system that uses dual identities for femtocells, including a primary and secondary scrambling code, where geolocation information is used to dynamically build a connected mode neighbor cell list and select the optimal secondary scrambling code for hand-in operations, allowing for open femtocell deployment and full integration into the macro network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional broadcasting methods are used to provide femtocell access information, then the system is simple to implement, but the number of femtocells that can be supported is limited by the broadcast capacity
Solution Approach 1:
The patent segments the femtocell identification system into two distinct parts: primary scrambling codes for idle mode cells and secondary scrambling codes for connected mode neighbor cells. This segmentation allows the system to support a much larger number of femtocells by distributing the identification burden across multiple codes rather than relying on a single broadcast list, directly resolving the contradiction between supporting more femtocells and maintaining system simplicity.
2Adaptability or versatility
If a single scrambling code is used for femtocell identification, then the configuration is simple, but the flexibility for hand-in and hand-out operations is limited
Solution Approach 1:
The patent implements multi-functionality by assigning dual identities to femtocells: primary scrambling codes serve for idle mode cell selection and initial access, while secondary scrambling codes are used for connected mode neighbor cell lists and handover operations. This universal approach allows the same femtocell to be accessed through multiple pathways depending on the operational mode, greatly enhancing adaptability for hand-in and hand-out scenarios while maintaining manageable configuration complexity.
3Measurement precision
If geolocation information is used to dynamically select femtocells, then the accuracy of femtocell selection is improved, but the processing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring both primary and secondary scrambling codes for each femtocell before deployment. The network element stores these codes in advance and uses geolocation information to efficiently select the appropriate secondary scrambling code when building connected mode neighbor cell lists. This pre-preparation significantly reduces real-time processing complexity while maintaining high selection accuracy, as the system only needs to perform lookup and selection operations rather than complex calculations during handover decisions.
Data Source
AI summary
A method is provided in one example embodiment and includes evaluating geolocation information associated with a mobile node and using the geolocation information to identify a femtocell capable of providing network access to the mobile node. A primary scrambling code is provided to the mobile node for operation in an idle mode. The method also includes communicating a secondary scrambling code to initiate access to the femtocell by the mobile node when operating in an active mode. In more particular embodiments, the secondary scrambling code is included in a broadcast message that includes a femtocell identifier associated with the femtocell. The femtocell is identified from a plurality of femtocells based on geolocation information associated with the femtocell. The primary scrambling code is part of a range of primary scrambling codes allocated to a plurality of femtocells within a macro network coverage area.