DMRS Port Assignment for Inter-Cell Interference Cancellation
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Solution Overview
Problem
The increased cell density in wireless networks due to small cell deployment leads to higher inter-cell interference, severely impacting user equipment (UE) data throughput, especially at the cell edge, as existing advanced receiver algorithms require knowledge of interfering signals to effectively cancel and suppress interference.
Innovation Solution
The method involves assigning orthogonal antenna ports to each base station and neighboring base stations for transmitting user equipment-specific reference signals, with a common DMRS scrambling identity, and transmitting this information to UEs to facilitate inter-cell interference cancellation by recovering DMRS information from interfering signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If small cell deployment is used to increase cell density and data capacity, then network capacity and coverage are improved, but inter-cell interference increases severely impacting UE data throughput
Solution Approach 1:
The patent changes the parameter of DMRS transmission by assigning different antenna ports to serving and interfering base stations, and using a common scrambling identity. This parameter modification enables the UE to distinguish and cancel interference from neighboring cells while maintaining high network capacity from small cell deployment.
Solution Approach 2:
The patent introduces DMRS information as an intermediary element that carries identification and channel state information about interfering signals. By recovering and utilizing this intermediary information, the UE can perform interference cancellation without directly processing the harmful interfering signals themselves.
2Reliability
If advanced receiver algorithms are employed to cancel and suppress inter-cell interference, then UE performance is improved, but knowledge of interfering signals is required which increases receiver complexity
Solution Approach 1:
The patent performs preliminary action by having base stations pre-assign specific antenna ports and transmit DMRS information before the UE needs to perform interference cancellation. This preliminary configuration provides the UE with necessary interference signal characteristics in advance, reducing the complexity of real-time interference suppression operations.
Solution Approach 2:
The patent implements feedback by having the UE recover DMRS information from interfering signals and use it to improve its reception. The successfully cancelled interference provides feedback on the effectiveness of the algorithm, allowing for iterative improvement of UE performance without proportionally increasing complexity.
3Object-affected harmful factors
If orthogonal antenna ports are assigned to base stations with common DMRS scrambling identity, then interference cancellation is facilitated, but signaling overhead increases to transmit port information to UEs
Solution Approach 1:
The patent applies universality by using the common DMRS scrambling identity for multiple coordinating base stations. This single scrambling identity serves multiple functions: it identifies the group of coordinating cells, enables interference recognition, and facilitates cancellation across multiple base stations, reducing the need for separate signaling for each station.
Solution Approach 2:
The patent merges the antenna port information and scrambling identity into a unified signaling framework. By combining these elements into a coordinated transmission scheme, the patent reduces redundant signaling overhead while maintaining the ability to distinguish and cancel interference from multiple base stations.
Data Source
AI summary
Various devices and methods are provided that use enhanced downlink demodulation reference signals (DMRS) to facilitate inter-cell interference cancellation and suppression. Coordinated configuration of DMRS port assignments for transmission from cells in a group of neighboring cells is provided. Each cell's physical cell identification (PCID) is mapped with its corresponding assigned antenna port(s).