N1-N2 Bitmap Generation for Cellular Base Station Interference Mitigation
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Solution Overview
Problem
In wireless communication systems, especially in 5G and beyond, there is a challenge in reducing interference to satellite earth stations while maintaining coverage and performance, as cellular networks operating in adjacent bands can cause out-of-band emissions that affect satellite operations, leading to interference and compliance issues with regulatory power flux density thresholds.
Innovation Solution
The implementation of a method for generating an N1-N2 bitmap in base stations to restrict beamforming and reduce directional power towards satellite earth stations, using calculated power flux density, equivalent antenna gain, and directional power back-off levels, along with restricted precoding matrix indicators, to minimize interference while optimizing system throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If base stations increase transmit power to maintain coverage and performance, then cellular system coverage and throughput are improved, but interference to satellite earth stations increases causing regulatory compliance issues
Solution Approach 1:
The patent applies local quality by making the transmit power directional rather than uniform. The base station identifies specific geographic locations (earth station coordinates) and applies power back-off only in those specific directions while maintaining full power in other directions. This is achieved through calculating power flux density in specific directions and generating location-specific bitmap indicators that restrict beams only where earth stations are present, thus locally reducing interference while globally maintaining system throughput.
Solution Approach 2:
The patent implements dynamics by making the power transmission pattern adaptive and changeable. The base station continuously monitors for earth station locations, calculates directional power back-off levels dynamically, and updates bitmap indicators in real-time as earth stations move or new ones are detected. This dynamic adjustment allows the system to optimize power distribution continuously, reducing interference to satellite operations while maintaining maximum cellular performance when possible.
2Reliability
If base stations apply directional power back-off to reduce interference to earth stations, then regulatory compliance is improved, but coverage and system performance deteriorate
Solution Approach 1:
The patent ensures regulatory compliance through local quality by applying power back-off restrictions only in specific geographic directions where earth stations are located, rather than uniformly across all directions. The base station calculates power flux density for each direction and generates bitmap indicators that selectively restrict beams only in directions containing earth stations. This localized approach ensures compliance with power flux density thresholds while maintaining full transmit power in all other directions, thus preserving overall system throughput.
Solution Approach 2:
The patent applies partial action by implementing power back-off only partially - specifically in directions where earth stations are present - rather than applying it excessively across all directions. The base station identifies the minimum necessary restrictions by calculating directional power flux density and comparing it against regulatory thresholds, then applies back-off only to the extent needed for compliance. This partial application minimizes the impact on cellular system performance while achieving the necessary regulatory compliance.
3Object-affected harmful factors
If base stations restrict beamforming directions using N1-N2 bitmap, then interference to satellite operations is reduced, but spatial multiplexing capability is limited
Solution Approach 1:
The patent applies segmentation by dividing the spatial domain into discrete beam directions represented by bitmap indicators. Instead of continuously adjusting beamforming weights, the system segments the angular space into N1 horizontal and N2 vertical beams, creating a grid of discrete directions. Each bitmap bit corresponds to a specific beam direction, allowing the base station to independently control each segmented direction. This segmentation simplifies the complexity by transforming a continuous optimization problem into a discrete selection problem, making it easier to manage beam restrictions while reducing interference to satellite operations.
Solution Approach 2:
The patent implements dynamics by making the beamforming configuration adaptive and changeable over time. The base station dynamically generates and updates N1-N2 bitmap indicators based on real-time detection of earth station locations and movements. As earth stations move or new ones are detected, the bitmap configuration is updated to reflect current spatial restrictions. This dynamic approach allows the system to adapt to changing spatial conditions, maintaining optimal interference reduction while preserving beamforming flexibility and spatial multiplexing capability when restrictions are not needed.
Data Source
AI summary
Methods and apparatuses in a wireless communication system. A base station (BS) includes a transceiver and a processor. The processor regulates a transmit power in a direction of an earth station or a predefined receiver by: calculating a power flux density for the BS to the earth station or the predefined receiver; calculating an equivalent antenna gain for other base stations; calculating a directional power back-off level for the other base stations with respect to the earth station or the predefined receiver; generating a restricted precoding matrix indicator based on the calculated directional power back-off level; generating an N1-N2 bitmap for the BS; and applying the N1-N2 bitmap for signal transmission to at least one UE. The N1-N2 bitmap is generated based on: physical parameters of the earth station of the predefined receiver; physical parameters of the BS; an operator input metric; or restricted precoding matrix indicator.