Femtocell Carrier Selection for Macro Interference
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Solution Overview
Problem
Co-channel deployment between macro and femtocell layers in cellular networks causes interference, leading to degradation of macro network quality and unauthorized handsets experiencing service disruptions or channel blocking, which affects user experience and network capacity.
Innovation Solution
A method for a femtocell basestation to select a carrier that partially overlaps with adjacent macro layer carriers, using a channel offset to minimize interference while ensuring seamless handover between layers, by configuring inter-frequency cell reselection parameters and adjusting power settings based on measured signal strengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If co-channel deployment is used between macro and femtocell layers, then mobility between layers is simplified and handsets can easily search for femtocell coverage, but interference between the two layers degrades macro network quality and causes service disruptions for unauthorized handsets
Solution Approach 1:
The patent changes the frequency parameter by allocating a dedicated frequency for femtocell basestations instead of using co-channel deployment. This frequency separation eliminates interference between macro and femto layers while maintaining mobility capabilities through inter-frequency cell reselection parameters and compressed mode measurements.
2Object-affected harmful factors
If a dedicated frequency is allocated to femtocell basestations, then interference between macro and femto layers is eliminated, but all handsets must search for femtocell coverage causing capacity and quality problems
Solution Approach 1:
The patent applies local quality by configuring inter-frequency cell reselection parameters selectively on macro layer basestations in proximity to femtocell basestations. This targeted approach ensures only handsets in the femtocell coverage area search for and measure femtocell signals, preventing network-wide capacity degradation while maintaining interference-free operation.
3Adaptability or versatility
If inter-frequency cell reselection parameters are configured on macro network, then handsets can detect femtocell layer, but handsets in connected mode require compressed mode which reduces capacity and quality
Solution Approach 1:
The patent uses partial action by configuring inter-frequency cell reselection parameters only on specific macro layer basestations that are geographically close to femtocell basestations, rather than network-wide. This selective configuration minimizes the number of handsets requiring compressed mode measurements, preserving network capacity and quality while enabling femtocell detection where needed.
Data Source
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AI summary
A femtocell basestation selects its carrier frequency by detecting a carrier used by at least one other basestation in its network, and selecting its own carrier frequency such that it partially overlaps with the detected carrier. The downlink power of the femtocell basestation is set based on the degree of overlap between the selected carrier and the detected carrier, so that a user equipment having a connection to the other basestation is forced to search for the selected carrier.