Synchronized Subframe Assignment for Macro and CSG Cell Interference
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Solution Overview
Problem
In mobile communication systems, interference between Home NodeB (HeNB)/Home NodeB (HNB) cells and macro cells leads to communication disruptions due to increased interference power, especially when HeNB/HNB cells are installed within macro cell coverage, causing UEs to lose connection during handover or cell reselection.
Innovation Solution
Implementing a mobile communication system where HeNB/HNB cells and macro cells use orthogonal frequency division multiplexing (OFDM) for downlink and single carrier frequency division multiple access (SC-FDMA) for uplink, with synchronized control signal transmission using radio frames that assign control signals to specific subframes, and managing cell identification information to facilitate proper handover and cell selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If HeNB/HNB cells are installed within macro cell coverage to provide localized service, then service coverage and accessibility are improved, but interference power increases causing communication disruptions
Solution Approach 1:
The system segments the coverage area into macro cell regions and HeNB/HNB regions, allowing each to operate independently with optimized parameters. The macro cell provides broad coverage while HeNB/HNB cells provide localized high-speed access, reducing mutual interference through spatial segmentation of services.
Solution Approach 2:
The system changes transmission parameters dynamically based on cell type and user location. By adjusting modulation schemes, coding rates, and power allocation according to channel conditions and cell characteristics, the system optimizes performance while managing interference between macro and HeNB/HNB cells.
2Productivity
If control signals are transmitted simultaneously from multiple base stations, then communication efficiency is improved, but signal overlap and interference increase
Solution Approach 1:
The system uses periodic transmission patterns for control signals with carefully designed periods and offsets. By transmitting control signals in periodic intervals rather than continuously, and by staggering the timing between different base stations, the system maintains high communication efficiency while avoiding signal overlap and interference.
3Adaptability or versatility
If UEs perform handover between cells with different access schemes, then mobility and service continuity are improved, but handover failures and disconnections increase
Solution Approach 1:
The system introduces an intermediary handover management mechanism that coordinates the handover process between cells with different access schemes. The intermediary entity prepares target cell resources in advance, validates compatibility between source and target cells, and manages the transition smoothly, thereby maintaining mobility while ensuring handover reliability.
Data Source
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AI summary
There is a problem that when a closed subscriber group (CSG) cell (1303) available to subscribers is installed in a macro cell area (1301), communication cannot be performed due to the interference between a macro cell (1302) and the CSG cell (1303) in an area (1304) thereof. The CSG cell (1303) that is provided in the CSG cell area (1304) and transmits a downlink synchronization signal using a radio frame assigns control signals to a first subframe and a second subframe among a plurality of subframes constituting the radio frame, and the macro cell (1302) that is provided in the macro cell area (1301) and transmits a downlink synchronization signal using the radio frame assigns control signals to a third subframe and a fourth subframe, which are shifted from the first subframe and the second subframe by a predetermined number of subframes, respectively, among the plurality of subframes constituting the radio wave, the CSG cell (1303) and the macro cell (1302) being configured to perform transmission in synchronization with each other.