PCI Adaptation for Interference Mitigation in Heterogeneous Networks
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Solution Overview
Problem
In cellular radio communications, interference between base stations and user equipment (UEs) in heterogeneous networks, particularly due to the deployment of Closed Subscriber Group (CSG) Home eNBs, leads to reduced throughput and coverage for non-CSG UEs, and challenges in physical cell identifier (PCI) planning, especially in densely populated areas.
Innovation Solution
A radio network node adapts its cell identifier based on radio measurements from neighboring nodes, replacing or aligning its identifier to mitigate interference, facilitate handovers, and optimize network management tasks such as resource allocation and interference reduction, by comparing and potentially replacing its physical cell identifier with that of a neighboring node, and setting up coordinated multi-point transmission/reception sessions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CSG HeNBs are deployed as overlay to macro network, then local coverage and throughput for in-building users is improved, but interference to non-CSG MUEs increases
Solution Approach 1:
The patent applies local quality by configuring different PCI parameters for different geographical locations and deployment scenarios. Specifically, the system assigns distinct PCI values to CSG HeNBs based on their location relative to macro cells and other HeNBs, ensuring that each local area has optimized PCI configuration to minimize interference to non-CSG users while maintaining service quality for CSG users.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting PCI values based on deployment density, geographical location, and interference conditions. The system modifies PCI parameters according to the number of HeNBs in the area, their spatial distribution, and the resulting interference patterns, thereby optimizing network performance for both CSG and non-CSG users under varying conditions.
2Device complexity
If HeNBs reuse PCIs in densely populated areas, then device complexity and deployment cost are reduced, but interference and network performance deteriorate
Solution Approach 1:
The patent applies dynamics by transitioning from static PCI assignment to dynamic PCI selection based on real-time or near-real-time interference measurements and network conditions. The system continuously monitors interference levels and adjusts PCI configurations accordingly, allowing the network to adapt to changing deployment scenarios, user distributions, and interference patterns in densely populated areas.
Solution Approach 2:
The patent implements feedback mechanisms where the network monitors interference caused by PCI reuse and uses this information to adjust PCI assignments. The system collects interference measurement data from HeNBs and macro cells, analyzes the impact of PCI configurations, and provides feedback to optimize PCI allocation, thereby maintaining network performance while enabling dense deployment.
3Object-affected harmful factors
If HeNBs autonomously control transmit power, then interference to non-CSG MUEs is reduced, but throughput for CSG HUEs may be overly reduced
Solution Approach 1:
The patent applies parameter changes by adjusting transmit power levels based on PCI configuration and interference conditions. Rather than using fixed autonomous power control, the system modifies power parameters in coordination with PCI selection, allowing flexible trade-offs between interference reduction and throughput maintenance depending on the specific deployment scenario and user distribution.
Data Source
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AI summary
A first radio network node (HBS |) adapts its physical cell identifier (PCI1) based on a comparison of its PCI1 to a second PCI (PCI2) used by a neighboring interfering second radio network node (e.g., another HBS2 or a macro node). The first radio network node HBS1 determines the second PCI based on one or more radio measurements performed on a cell 402 and/or on a UE 404 served by the second node. The adaptation of the cell identifier PCI1 is used for one or more radio network management tasks, e.g., resource management such as interference mitigation in a heterogeneous network, radio network planning, etc.