Virtual Femto Node for Macro-to-Femtocell Handover
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Solution Overview
Problem
Conventional wireless communication systems face inefficiencies in macrocell-to-femtocell handover due to high deployment density of femtocells, leading to strained conventional neighbor-handling capabilities and inefficient access control, especially in indoor environments where path loss and channel quality degradation occur.
Innovation Solution
The implementation of a system that uses a virtual femto node to represent multiple femto access points, allowing for reduced macro-to-femto relationships and associations, and employs location estimates based on GNSS and TOF measurements to select the target femto access point, while verifying access privileges through an access list to ensure seamless handover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If femtocells are deployed at high density to improve indoor coverage, then coverage quality is improved, but handover complexity and signaling overhead increase substantially
Solution Approach 1:
The patent merges multiple femtocell access points into a single virtual femto node representation. Instead of managing handovers to each individual femtocell separately, the system consolidates them into one logical entity, reducing the number of handover relationships from O(N) to O(1) where N is the number of femtocells. This merging approach maintains comprehensive indoor coverage while eliminating the complexity explosion that would otherwise occur at high deployment densities.
Solution Approach 2:
The virtual femto node acts as an intermediary between the macrocell and the multiple femtocell access points. It serves as a single point of contact for handover decisions, simplifying the macrocell's neighbor relationship management while still enabling access to multiple physical femtocells. The virtual node mediates the handover process by receiving handover requests from the macrocell and routing them to appropriate femtocell access points based on subscriber location and access privileges.
2Adaptability or versatility
If conventional neighbor-handling capabilities are used for macro-to-femto handover, then handover can be performed, but the system strains under high femtocell deployment density of 10^5-10^6 femtocells per macrocell
Solution Approach 1:
The patent merges the representation of numerous femtocell access points into a single virtual femto node in the handover neighbor list. This consolidation reduces the number of handover associations from potentially hundreds of thousands to a single entry, enabling the system to efficiently handle the expected high-density deployment of 10^5-10^6 femtocells per macrocell without straining conventional neighbor-handling capabilities.
Solution Approach 2:
The patent segments the femtocell access points into a logical group represented by a virtual node, separating the handover management function from individual femtocell identities. This segmentation allows the macrocell to maintain a simplified neighbor relationship while the virtual node internally manages connections to multiple physical femtocells, improving system efficiency under high deployment density.
3Reliability
If access control is implemented for femtocell handover, then security is improved, but signaling overhead and processing time increase
Solution Approach 1:
The patent implements preliminary action by pre-configuring access control lists at the virtual femto node before handover occurs. The macrocell and network infrastructure prepare access authorization data in advance, so that during the actual handover process, access verification can be performed rapidly using pre-computed criteria. This preliminary preparation of access control information reduces the time penalty that would otherwise be incurred during the handover execution phase.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the complexity of handover processes, enhances battery life by minimizing unnecessary signaling, and ensures efficient access control, thereby improving the overall performance of macrocell-to-femtocell transitions in high-density femtocell deployments.
Implementation Method 1
employs location estimates based on GNSS and TOF measurements to select the target femto access point
Data Source
AI summary
Access to a femtocell can be controlled as part of handover of a mobile device from macrocell to femtocell. Macro network platform issues a handover (HO) request towards femto network platform and a single virtual femto node, which represents a plurality of femto access points (APs). Location estimate(s) for the mobile device drives selection of a target femto AP. Selection of the target AP results in acceptance of the HO request. The mobile device also can request macro-to-femto (MTF) handover. HO neighbor list(s) is generated by decoding a network-issued identifier for each femto APs in a set of femtocells, and selectively ranking each femto AP based at least on channel quality; access privileges of the mobile device to each of the identified femto APs determines selectivity. Validation of mobile device's access right(s) drives acceptance of the MTF HO request to a top ranked femto AP.