Base Station Beamforming Nulls for Semi-Synchronous TDD Interference
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Solution Overview
Problem
Current wireless communication systems face challenges in mitigating interference between base stations operating with different Time Division Duplex (TDD) configurations, leading to inefficient spectrum utilization and potential performance impacts due to cross-link interference, especially in semi-synchronous or asynchronous TDD operations across adjacent networks.
Innovation Solution
The solution involves determining the likelihood of interference between base stations based on their locations and forming nulls in downlink transmissions to avoid interfering with uplink signals, as well as adjusting transmission schedules based on user equipment elevation angles to prevent cross-link interference, allowing for more flexible deployments without the need for large guard bands or coordinated duplex directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If base stations operate with different TDD configurations to increase spectrum utilization flexibility, then spectrum efficiency is improved, but cross-link interference between base stations increases
Solution Approach 1:
The patent applies local quality by forming directional nulls in the beam pattern specifically toward interfering base stations. Instead of uniformly reducing transmission power in all directions, the system maintains high power transmission in most directions while creating localized nulls only in the directions where interference occurs. This allows flexible TDD operation to continue while mitigating cross-link interference in specific spatial locations.
Solution Approach 2:
The patent changes the spatial parameter of the transmission beam by dynamically adjusting beamforming weights to create nulls in specific directions. By modifying the angular distribution of transmitted energy rather than changing frequency or time parameters, the system enables flexible TDD configurations while preventing downlink transmissions from interfering with uplink receptions at neighboring base stations.
2Adaptability or versatility
If base stations use semi-synchronous or asynchronous TDD operations to avoid coordinated duplex directions, then deployment flexibility is improved, but interference mitigation capability deteriorates
Solution Approach 1:
The patent implements self-service by enabling each base station to autonomously identify interfering directions and form nulls without requiring coordination with neighboring base stations. The system independently determines which directions contain interfering base stations and adjusts its beamforming accordingly, allowing semi-synchronous or asynchronous TDD operations to proceed without complex inter-base-station coordination while still achieving interference mitigation.
3Object-affected harmful factors
If large guard bands are used to prevent cross-link interference, then interference mitigation is improved, but spectrum utilization efficiency deteriorates
Solution Approach 1:
The patent transitions from frequency-domain interference mitigation (guard bands) to spatial-domain interference mitigation (directional nulls). Instead of leaving unused frequency resources as guard bands, the system utilizes the spatial dimension by forming directional nulls in the beam pattern. This allows full utilization of the allocated spectrum while preventing interference through spatial filtering, effectively moving the solution from one dimension (frequency) to another dimension (space).
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces cross-link interference, enhances spectrum efficiency, and allows for more flexible network deployments by minimizing the impact of interference between base stations, thereby improving overall network performance and reducing throughput loss.
Implementation Method 1
forming a null in a beam of the downlink transmission in a direction matching the location of the other base station
Data Source
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AI summary
Certain aspects of the present disclosure provide techniques for interference mitigation. An exemplary method performed by a base station generally includes determining, based on a location of another base station and information regarding the other base station, that the other base station is likely to experience interference while receiving an uplink transmission due to a downlink transmission by the base station and forming a null in a beam of the downlink transmission in a direction matching the location of the other base station.