Interference Coordination in Millimeter Wave Cellular Systems
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Solution Overview
Problem
Intercell interference in millimeter wave (mmWave) communications systems, particularly when adjacent cells use different time division duplexed (TDD) frame configurations, leads to reduced cell capacity and increased interference, as traditional techniques cluster cells into the same TDD configuration, not optimizing for individual uplink/downlink load conditions.
Innovation Solution
Each evolved NodeB (eNB) is allowed to select its optimal TDD frame configuration based on its specific load conditions and shares this information with neighbors to minimize interference through beamforming scheduling decisions, using transmit and receive beam blanking to avoid high interference directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If cells are clustered into the same TDD configuration, then intercell interference is reduced, but cell capacity is not optimized for individual uplink/downlink load conditions
Solution Approach 1:
The system segments the network into individual cells that can independently select TDD configurations based on their specific uplink/downlink load conditions, rather than forcing all cells to use the same configuration. This allows each cell to be optimized independently while still coordinating with neighbors to manage interference.
Solution Approach 2:
The system enables dynamic TDD configuration selection where each cell can adapt its TDD configuration based on real-time or near-real-time traffic conditions. This dynamic adaptation allows cells to respond to changing load conditions while maintaining interference coordination through information sharing with neighboring cells.
2Productivity
If each eNB selects optimal TDD configuration independently, then cell capacity is optimized, but intercell interference increases due to configuration mismatches
Solution Approach 1:
The system implements feedback mechanisms where eNBs share their selected TDD configuration information with neighboring cells. This feedback allows neighbors to be aware of each other's configurations and adjust their beamforming scheduling decisions accordingly, preventing severe interference while maintaining individual cell optimization.
Solution Approach 2:
The patent introduces an intermediary coordination mechanism where eNBs exchange configuration information through a standardized interface. This intermediary layer enables independent optimization while coordinating interference management, as each eNB can make independent decisions but with knowledge of neighbor configurations to avoid severe interference scenarios.
3Illumination intensity
If beamforming is used in mmWave systems, then signal coverage is improved, but intercell interference becomes more directional and severe
Solution Approach 1:
The system performs preliminary actions by having eNBs share their TDD configuration and beamforming scheduling information with neighbors before actual transmissions occur. This advance coordination allows neighboring eNBs to schedule their beams to avoid directional interference, particularly by coordinating which subframes use directional beamforming versus omnidirectional transmissions.
Solution Approach 2:
The patent applies local quality by allowing each cell to optimize its beamforming characteristics based on its specific traffic conditions and neighbor configurations. Different cells can use different beamforming strategies (directional vs. omnidirectional) in different subframes based on their local needs, while coordination ensures that directional beams do not cause severe interference to neighbors during critical subframes.
Data Source
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AI summary
A method for communicating in a communications system using beamformed transmissions includes blanking an interference antenna beam out of a plurality of available antenna beams that one of causes interference to and receives interference from at least one neighboring base station during a conflict time interval of a frame, wherein the blanking is in accordance with configuration information comprising frame configuration information received from the at least one neighboring base station and frame configuration information of a serving base station (SBS), thereby producing a plurality of candidate antenna beams, scheduling communications opportunities for user equipments (UEs) in the conflict time interval on the plurality of candidate antenna beams, and communicating with scheduled UEs using the communications opportunities.