Antenna Port Selection for Distributed RRHs in LTE Mobility
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Solution Overview
Problem
Current wireless communication systems, particularly in LTE networks, face challenges in supporting mobility procedures effectively with multiple distributed remote radio heads (RRHs), as existing methods do not efficiently manage antenna port selection based on user equipment (UE) mobility and location changes, leading to potential performance losses due to unequal path losses and colliding reference signals.
Innovation Solution
The method involves receiving channel state information (CSI) feedback from user equipment (UE) to select and update antenna ports for transmitting reference signals, including those of base stations and remote radio heads (RRHs), based on UE mobility and location changes, optimizing antenna port configuration to account for varying path losses and improve signal differentiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If antenna ports are selected based on fixed configuration without considering UE mobility, then device complexity is reduced, but signal quality deteriorates due to unequal path losses and colliding reference signals
Solution Approach 1:
The patent implements dynamic antenna port selection that adapts to UE mobility conditions. The system transitions from static configuration to dynamic adjustment based on UE location and mobility state, selecting appropriate antenna ports (e.g., eNB ports vs. RRH ports) according to real-time channel conditions and UE movement patterns
Solution Approach 2:
The system uses CSI feedback from the UE to inform antenna port selection decisions. The UE reports channel state information that helps the eNB determine the optimal antenna port configuration, creating a feedback loop that continuously optimizes signal quality based on actual channel conditions
2Reliability
If antenna ports are updated frequently to track UE mobility, then signal quality is improved, but loss of time increases due to reconfiguration overhead
Solution Approach 1:
The system implements periodic antenna port selection updates triggered by mobility events or time intervals rather than continuous reconfiguration. This periodic approach maintains signal quality by updating ports at appropriate intervals while minimizing unnecessary reconfiguration overhead and time loss
Solution Approach 2:
The patent changes the parameter of antenna port selection based on UE mobility parameters such as speed and location. By monitoring mobility parameters and adjusting antenna port configuration accordingly, the system optimizes performance without excessive reconfiguration, updating only when mobility conditions warrant a change
3Area of stationary object
If all remote radio heads transmit reference signals on all antenna ports, then coverage is improved, but interference increases due to colliding reference signals
Solution Approach 1:
The patent applies local quality by assigning different antenna ports to different RRHs based on their geographic locations and coverage areas. Each RRH transmits reference signals on specific antenna ports appropriate to its local coverage zone, preventing reference signal collisions while maintaining comprehensive coverage through coordinated transmission
Solution Approach 2:
The system segments the antenna port resource space by assigning specific antenna ports to specific RRHs. This segmentation divides the reference signal transmission resources across multiple RRHs, allowing each to transmit on dedicated ports without collision while collectively providing wide coverage
Data Source
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AI summary
Wireless networks may include remote radio heads (RRHs) for extending the coverage of a macro cell. The macro cell may be connected to the RRHs, for example, by optical fiber, and there may be negligible latency between the macro cell and the RRHs. As a user equipment (UE) moves within the macro cell, or between other macro cells, mobility procedures followed by the UE may vary based on the release of the UE (e.g., Rel-8/9, Rel-10, or Rel-11 and beyond). The macro cell may handle all the scheduling within the cell, for itself and the RRHs. The method comprises the steps of: - Receiving CSI feedback from a user equipment based on the CSI feedback, select one or more antenna ports for transmitting reference signals, wherein the one or more antenna ports are a least antenna ports of a base station or antenna ports of remote radio heads under control of the base station, - determine whether to update the selection of the one or more antenna ports based at least in part on a change in location or a mobility of the user equipment.