Uplink Beam Selection Under MPE Limits in Multi-Beam 5G
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Solution Overview
Problem
Existing 5G wireless networks face challenges in uplink beam selection that comply with maximum permissible exposure (MPE) limits and avoid link failure, particularly in the presence of human bodies, which can lead to interference and reduced network performance.
Innovation Solution
A method for uplink beam selection in 5G networks that involves beam sweeping to identify and select uplink beams satisfying MPE limits and avoiding link failure, using reference signals like CSI-RS and SSBs, with power management and human body detection to optimize beam alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If uplink beam selection is performed without considering MPE limits, then uplink transmission power can be maximized, but human body exposure limits are exceeded causing link failures
Solution Approach 1:
The system performs preliminary beam sweeping and measurement of reference signals before actual uplink transmission to identify beams that satisfy MPE limits. This preliminary action allows the selection of safe beams in advance, avoiding the need to reduce power during transmission while still protecting against excessive human body exposure.
Solution Approach 2:
The system changes the selection criteria for uplink beams by introducing MPE limit satisfaction as a key parameter. Instead of simply selecting beams with highest power, the system evaluates and selects beams based on whether they meet the MPE limits, thus changing the optimization parameter from pure power maximization to power optimization within safety constraints.
2Reliability
If beam sweeping process is implemented to identify MPE-compliant beams, then link reliability is improved, but system complexity and measurement overhead increase
Solution Approach 1:
The beam sweeping process serves multiple functions simultaneously: it identifies the best uplink beams for transmission, determines which beams satisfy MPE limits, and provides measurement data for beam selection. This multi-functionality reduces the need for separate procedures and minimizes overall system complexity despite the comprehensive beam evaluation required.
Solution Approach 2:
The user equipment (UE) autonomously performs the beam sweeping, measurement, and selection process based on downlink beam measurements. The UE independently determines the uplink beam correspondence and identifies MPE-compliant beams without requiring complex network-side coordination, thus reducing overall system complexity while maintaining reliability.
3Ease of operation
If uplink-downlink beam correspondence is assumed, then beam selection is simplified, but accuracy deteriorates when correspondence does not hold
Solution Approach 1:
The system dynamically adapts its beam selection approach based on the actual beam correspondence conditions. When downlink beam measurements indicate strong correspondence, the system uses the simplified assumption. When measurements show poor correspondence, the system transitions to a more rigorous measurement-based selection process, thus maintaining both simplicity and accuracy in different operating conditions.
Solution Approach 2:
The system uses feedback from downlink reference signal measurements to validate the uplink-downlink beam correspondence assumption. By measuring downlink beams and comparing with uplink performance, the system can detect when correspondence breaks down and adjust its beam selection strategy accordingly, maintaining measurement precision while preserving operational simplicity when conditions permit.
Data Source
AI summary
A method of uplink beam selection that includes receiving, by a user equipment (UE), one or more messages comprising configuration parameters of reference signals associated with a plurality of downlink beams comprising a first downlink beam; first determining, based on a beam sweeping process comprising measurement, of the reference signals, a plurality of uplink beams associated with the first downlink beam; second determining a first subset of uplink beams, of the plurality of uplink beams, that satisfy maximum permissible exposure (MPE) limits and that are not subject to link failure; first transmitting, to a base station (BS), a configuration message including configuration parameters of the first subset of the uplink beams; and second transmitting, by the UE, uplink data or control information using one or more beams of the first subset of the uplink beams.