Weighted Path Loss Metric for Coordinated Reception Power Control
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Solution Overview
Problem
Current uplink power control methods in wireless communication systems with coordinated multi-point reception are inaccurate due to the difficulty in estimating a single propagation loss metric for signals jointly received by multiple geographically separated reception points, leading to suboptimal power adjustment and varying Signal-to-Noise Ratios across reception points.
Innovation Solution
A method for estimating a weighted sum of individual propagation losses from a mobile station to coordinated reception points, expressed in decibels, to serve as a propagation loss metric for power control, ensuring the uplink transmit power is adjusted based on the largest propagation loss, with dynamically selectable weights to meet performance metrics like system throughput and QoS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single propagation loss metric is used for power control in CoMP systems, then power control simplicity is maintained, but measurement precision deteriorates due to the difficulty in estimating a single metric for multiple geographically separated reception points
Solution Approach 1:
The patent segments the propagation loss estimation by introducing separate path loss metrics for different reception points (e.g., primary reception point path loss and secondary reception point path loss) rather than using a single aggregated metric. This allows each reception point to have its own accurate path loss measurement while maintaining manageable power control complexity through structured segmentation of the estimation process
Solution Approach 2:
The patent changes the parameter representation by using multiple path loss metrics (PL1, PL2, etc.) instead of a single path loss value. Each metric corresponds to a specific reception point and can be independently adjusted, enabling precise power control for each point while maintaining overall system manageability through parameter differentiation
2Reliability
If uplink transmit power is adjusted based on the largest propagation loss, then reliability is improved by ensuring adequate power for the closest reception point, but use of energy deteriorates due to suboptimal power adjustment
Solution Approach 1:
The patent applies local quality by assigning different path loss metrics to different reception points based on their specific characteristics and distances. Each reception point receives tailored path loss information (PL1 for primary, PL2 for secondary) that reflects its local propagation conditions, enabling optimized power adjustment for each point rather than a one-size-fits-all approach
Solution Approach 2:
The patent introduces dynamic power adjustment by allowing the UE to switch between different path loss metrics (PL1, PL2, etc.) based on which reception point is currently the primary target. The power control parameter PO_Nominal and path loss compensation factor α are dynamically adjusted based on the selected path loss metric, enabling adaptive energy efficiency while maintaining reliability
3Measurement precision
If multiple path loss metrics are used for different reception points, then measurement precision is improved, but device complexity increases due to the need to manage and coordinate multiple metrics
Solution Approach 1:
The patent applies preliminary action by having the network pre-configure multiple path loss metrics (PL1, PL2, etc.) and associated power control parameters (PO_Nominal, α) before uplink transmission. The UE receives these configurations in advance through RRC signaling and can directly use them without complex real-time calculations, reducing device complexity while maintaining measurement precision
Solution Approach 2:
The patent implements feedback mechanisms where the network monitors uplink reception quality at different reception points and adjusts the path loss metrics and power control parameters accordingly. This feedback loop enables the network to optimize the multiple path loss metrics based on actual channel conditions, managing complexity centrally while maintaining precision at the edge
Data Source
AI summary
The present invention relates to a method for power control in a wireless communication system comprising at least one mobile station and N number of coordinated reception points with indices n=1, . . . , N, with the coordinated reception points being spatially separated and adapted for receiving transmissions from the mobile station, the method comprising the steps of: estimating a propagation loss metric LUL for the mobile station, the propagation loss metric LUL being a weighted sum of individual propagation losses Ln from the mobile station to the coordinated reception points expressed in dB multiplied with associated weights wn; and using propagation loss metric LUL for power control of mobile station. Furthermore, the invention also relates to a method in a network control device, a method in a mobile station, a computer program, a computer program product, a network control device and a mobile station device.