Micro Base Station Downlink Control Channel Symbol Shifting
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Solution Overview
Problem
In HetNets, severe interference occurs from macro base stations with higher transmission power to small transmission power nodes, affecting the performance and coverage of micro cells.
Innovation Solution
A micro base station is configured to transmit signals with lower power and shift the downlink control channel's starting symbol to avoid overlap with quality measurement signals from macro cells, using techniques like Almost Blank Subframes and rate matching to reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a micro cell is formed by a small transmission power node with low transmission power in a macro cell, then the coverage area of the micro cell is limited, but severe interference is given from the macro base station to the small transmission power node
Solution Approach 1:
The subframe structure is segmented into different regions: the top symbol is allocated for quality measurement signals from macro cells, while the remaining symbols are used for downlink control channels in the micro cell. This temporal segmentation prevents interference between macro base station quality measurement signals and micro cell downlink control channels by assigning them to distinct time resources.
Solution Approach 2:
The starting symbol position of the downlink control channel is dynamically adjusted based on the presence of quality measurement signals. In subframes where quality measurement signals are transmitted by macro base stations, the downlink control channel starts from a later symbol position, avoiding the interfered top symbol. This dynamic adaptation allows the micro cell to maintain reliable control channel operation while coexisting with macro cell quality measurement activities.
2Stability of the object's composition
If the downlink control channel is arranged in the top several symbols of a micro cell subframe synchronized with the macro cell subframe, then the downlink control channel may overlap with quality measurement signals from macro cells, but maintaining synchronization is important for system operation
Solution Approach 1:
Different parts of the subframe are assigned different functions to avoid interference. The top symbol is reserved for quality measurement signals from macro cells, while the remaining symbols are used for downlink control channels in the micro cell. This local differentiation of resource usage within the subframe structure allows both macro and micro cells to operate simultaneously without mutual interference, maintaining synchronization while preventing harmful overlaps.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
The present invention is designed to reduce interference and relates to a radio communication control method in a radio base station, the method comprising the steps of allocating in a specific subframe, a physical downlink data channel (PDSCH) and a physical downlink control channel (X-PDCCH) by frequency-division-multiplexing to a first radio resource, from a first symbol in the first radio resource, the first radio resource being a data field corresponding to symbols following a first predetermined number of symbols in the specific subframe, and allocating, in another specific subframe, a physical downlink data channel (PDSCH) and a physical downlink control channel (X-PDCCH) by frequency-division-multiplexing to a second radio resource, the second radio resource being an expanded data field including given symbols prior to the first radio resource, the physical downlink data channel (PDSCH) being allocated to the second radio resource, from a first symbol in the second radio resource, and the physical downlink control channel (X-PDCCH) being allocated to symbols following the given symbols in the second radio resource; and notifying a user terminal (UE) of information about physical downlink control channel (X-PDCCH) configuration by higher layer signalling. The present invention is also characterized in providing a radio communication control method in a user terminal, a radio base station, a user terminal and a radio communication system.