Uplink-Downlink Co-Scheduling with PIM-Aware Beam Control
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Solution Overview
Problem
In wireless communication systems with a large number of antennas, passive intermodulation (PIM) interference cancellation becomes impractical due to numerical complexity, making traditional time domain PIM cancellation techniques unfeasible, and thus, PIM avoidance is explored to mitigate PIM issues.
Innovation Solution
The system employs advanced antenna systems (AAS) for uplink and downlink co-scheduling based on PIM awareness, using a learning phase to record beam steering directions and create a look-up-table of angles to schedule communications and modify directivity patterns to avoid 'bad' directional combinations that generate or receive PIM interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional time domain PIM cancellation techniques are used, then PIM interference can be reduced, but numerical complexity becomes too high when the number of antennas is large
Solution Approach 1:
The patent extracts and identifies specific PIM-prone directional combinations from the full antenna operation space, creating a restricted set of avoided combinations. Instead of processing all possible antenna combinations, the system extracts only the problematic ones into a lookup table, dramatically reducing computational complexity while maintaining PIM mitigation effectiveness
Solution Approach 2:
The system performs preliminary identification and recording of PIM-prone directional combinations during a learning phase before actual communication operations. By pre-computing and storing problematic antenna direction pairs in a lookup table, the system avoids real-time complex calculations during normal operation, resolving the contradiction between PIM cancellation and numerical complexity
2Object-affected harmful factors
If site clean-up is performed frequently to remove PIM sources, then PIM interference is reduced, but operational cost and time increase
Solution Approach 1:
The patent replaces mechanical site clean-up operations with a software-based beam control system. Instead of physically cleaning antennas to remove PIM sources, the system uses electronic beamforming to avoid directional combinations that generate PIM, substituting mechanical maintenance with intelligent signal processing
Solution Approach 2:
The system implements self-service by automatically identifying and avoiding PIM-prone directional combinations through beam control. The network autonomously manages PIM mitigation without requiring external technician intervention for site clean-ups, reducing both time and operational costs
3Productivity
If a large number of antennas are used for transmission and reception, then system capacity and coverage are improved, but PIM avoidance becomes more difficult due to increased directional combinations
Solution Approach 1:
The patent segments the large antenna system into manageable directional beams with discrete angles of departure and arrival. By dividing the continuous antenna space into discrete directional sectors, the system can efficiently manage PIM avoidance through beam-level control rather than individual antenna element control, making PIM management feasible for large-scale systems
Data Source
AI summary
A first radio node for uplink and downlink co-scheduling is provided. The first radio node includes processing circuitry containing instructions executable to configure the first radio node to: determine a scheduling restriction for joint uplink and downlink scheduling based on passive intermodulation (PIM) generated during simultaneous uplink and downlink communications where the uplink communications corresponds to communications from a second radio node to the first radio node, and perform communications according to the scheduling restriction.