Time Domain Interference Coordination in Heterogeneous LTE Networks
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Solution Overview
Problem
In heterogeneous LTE networks, load imbalance between macro and micro base stations leads to poor user experience and reduced system throughput due to inefficient time-domain interference coordination, particularly when user equipment moves and network load changes rapidly.
Innovation Solution
A time-domain interference coordination method that configures a first Almost Blank Subframe (ABS) proportion parameter and Cell Range Expansion (CRE) parameters for macro and micro cells to expand the micro cell's coverage area, thereby absorbing more user equipment from the macro cell and balancing load, using utility functions to optimize ABS and CRE settings for maximum system capacity and scheduling rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the offset value of CRE parameter is increased to expand micro base station coverage area, then more UEs can be absorbed by micro base station, but UE within CRE area is seriously interfered by macro base station
Solution Approach 1:
The invention segments the time domain into different types of subframes (ABS subframes and non-ABS subframes) to handle interference differently. During ABS subframes, the macro base station transmits only pilot signals, while during non-ABS subframes, it transmits user-specific channels. This temporal segmentation allows the micro base station to serve CRE UEs during ABS subframes with reduced interference, while still providing service during non-ABS subframes.
Solution Approach 2:
The invention implements periodic Almost Blank Subframes (ABS) where the macro base station periodically transmits only pilot signals instead of full downlink channels. This periodic action creates regular low-interference windows that allow CRE UEs to be served by the micro base station with acceptable signal quality, thus resolving the interference issue while maintaining expanded coverage.
2Device complexity
If ABS and CRE parameters are not simultaneously adjusted when network load changes, then configuration complexity is reduced, but load balance between macro and micro cells deteriorates
Solution Approach 1:
The invention implements a feedback mechanism where the network device monitors network load conditions and automatically adjusts both ABS subframe proportion parameters and CRE parameters based on the monitored load state. When the macro cell load exceeds a threshold, the system increases ABS proportion and adjusts CRE offset; when load decreases, it reduces ABS proportion. This closed-loop feedback ensures load balance is maintained without manual intervention.
Solution Approach 2:
The invention makes the ABS subframe proportion and CRE parameters dynamic rather than static. The ABS subframe proportion is adjusted based on real-time network load conditions, and the CRE offset parameter is dynamically modified in response to load changes. This dynamic adaptation allows the system to automatically optimize load distribution between macro and micro cells as network conditions change.
Data Source
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AI summary
The present invention discloses a time-domain interference coordination method, which includes: when load of a macro cell is greater than or equal to a load threshold, or when a timer reaches a system preset time, acquiring, by a network device, a first almost blank subframe ABS subframe proportion parameter of the macro cell and at least one cell range expansion CRE parameter, where the at least one cell range expansion CRE parameter is a CRE parameter for the macro cell and at least one micro cell, and the at least one micro cell is a micro cell within a coverage area of the macro cell; and configuring, by the network device, the first ABS subframe proportion parameter for the macro cell, and configuring the at least one CRE parameter for the macro cell and the at least one micro cell. According to the method of the present invention, when load of a macro cell is greater than or equal to a load threshold, a coverage area of a micro cell can be expanded, so that at least one micro cell adsorbs some user equipments UE that belong to the macro cell, and the load of the macro cell is reduced.