Femto Access Point Interference Management in Shared Spectrum
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Femto cells experience interference from WAN macro cells due to shared spectrum usage, which affects their performance, especially when WAN access terminals are restricted from connecting to femto cells, leading to interference on specific bandwidth portions.
Innovation Solution
A method and system where the femto access point intercepts control messages from WAN access points to determine jammed bandwidth portions and assigns alternative resources to femto access terminals, thereby mitigating interference by avoiding or utilizing unjammed bandwidth, using sector ID, hopping schemes, and system time data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If femto cells share the same spectrum with WAN macro cells, then spectrum utilization is improved, but signal interference increases
Solution Approach 1:
The patent segments the shared spectrum into multiple bandwidth portions and assigns different portions to WAN and femto cells based on interference conditions. The femto AP divides the available spectrum resources into distinct bands, selectively utilizing unjammed portions while avoiding interfered portions, thereby resolving the contradiction between spectrum utilization and interference avoidance.
Solution Approach 2:
The patent implements dynamic bandwidth portion assignment where the femto AP continuously monitors interference conditions and adapts its resource allocation in real-time. The system dynamically switches between different bandwidth portions based on current interference states, allowing flexible adaptation to changing spectrum conditions while maintaining optimal performance.
2Reliability
If femto cells restrict association to specific users, then network security is improved, but interference susceptibility increases
Solution Approach 1:
The patent implements preliminary interference detection and bandwidth assignment before femto ATs begin communication. The femto AP proactively identifies jammed bandwidth portions by intercepting WAN control messages and pre-assigns clean bandwidth portions to femto ATs, preventing interference issues before they occur while maintaining restricted association policies.
Solution Approach 2:
The patent introduces an intermediary mechanism where the femto AP intercepts and decodes WAN control messages to gain knowledge about WAN AT transmissions. This intermediary action allows the femto AP to indirectly monitor WAN spectrum usage and make informed bandwidth assignment decisions without directly interfering with WAN communications or relaxing association restrictions.
3Object-affected harmful factors
If femto AP intercepts control messages to avoid jammed bandwidth, then interference mitigation is improved, but system complexity increases
Solution Approach 1:
The patent implements a self-service mechanism where the femto AP autonomously intercepts, decodes, and processes WAN control messages to identify jammed bandwidth portions. The system automatically makes bandwidth assignment decisions based on intercepted information without requiring external intervention or complex coordination with WAN network elements, reducing overall system complexity while achieving effective interference mitigation.
Data Source
AI summary
Devices and methods are provided for adapting to interference in a spectrum shared by a WAN macro cell and a femto cell. In particular, described herein are techniques for adapting to the presence of a jamming WAN access terminal (AT) by avoiding or selectively utilizing those bandwidth portions jammed by the WAN AT/AP. For example, the technique may involve intercepting a control message from the WAN AP to the WAN AT, and determining a spectrum resource that the WAN AT will use to communicate with the WAN AP based at least in part on information (e.g., a Cell Radio Network Temporary Identifier, a Media Access Control Identifier, etc.) in the control message.