Millimeter-Wave Uplink Beam Selection Under MPE Constraints
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Solution Overview
Problem
Existing wireless communication systems face challenges in selecting uplink beams that comply with maximum permissible exposure (MPE) constraints, particularly in millimeter wave communications, leading to potential safety issues and suboptimal performance due to reciprocal beam pair assumptions.
Innovation Solution
User equipment (UE) determines transmit power based on MPE constraints, estimates receive power for the base station, and selects distinct uplink and downlink beams to ensure compliance with MPE limits while optimizing communication performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If reciprocal beam pair assumptions are used for uplink and downlink beam selection, then device complexity is reduced, but MPE compliance cannot be guaranteed and safety issues arise
Solution Approach 1:
The patent segments the beam selection process into independent uplink and downlink procedures. Instead of assuming reciprocal beam pairs, the system separately determines uplink transmit beams at the UE and downlink receive beams at the BS, allowing independent optimization and MPE constraint satisfaction for each direction.
Solution Approach 2:
The patent inverts the traditional approach by having the UE report MPE-related metrics (such as power headroom indicators or MPE constraint indicators) to the BS, rather than the BS directly controlling uplink beam selection. This allows the BS to make informed scheduling decisions while the UE maintains autonomy over its transmit beam choices to ensure MPE compliance.
2Reliability
If MPE constraints are strictly enforced by reducing transmit power, then safety compliance is improved, but communication performance deteriorates
Solution Approach 1:
The patent changes the parameter being optimized from transmit power alone to a combination of beam selection and power allocation. By introducing beam-specific MPE metrics and allowing different beams to have different power assignments, the system achieves MPE compliance without uniformly reducing power across all transmissions, thus maintaining communication performance.
Solution Approach 2:
The patent introduces dynamic beam selection and power adjustment mechanisms where the UE can switch between different uplink beams based on MPE conditions. When one beam approaches MPE limits, the system dynamically transitions to alternative beams, maintaining both safety compliance and communication performance through adaptive behavior.
3Reliability
If distinct uplink and downlink beams are selected, then MPE compliance is improved, but device complexity increases
Solution Approach 1:
The patent implements preliminary action by having the UE pre-report MPE-related metrics and candidate beam information to the BS before actual uplink transmissions. This advance information allows the BS to pre-determine appropriate beam pairs and power levels, reducing real-time complexity while ensuring MPE compliance.
Solution Approach 2:
The patent introduces an intermediary reporting mechanism where the UE provides MPE metrics and beam quality indicators to the BS. This intermediary information layer enables the BS to make intelligent beam selection decisions without the UE needing to implement complex beam management algorithms, distributing complexity appropriately between devices.
Data Source
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AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may determine, for a candidate UE uplink beam, a transmit power due to a maximum permissible exposure (MPE) constraint; estimate, for the candidate UE uplink beam, a receive power for a base station based at least in part on the transmit power due to the MPE constraint; determine a target receive power for the base station; and select the candidate UE uplink beam as an active UE uplink beam based at least in part on the estimated receive power for the base station and the target receive power for the base station. Numerous other aspects are provided.