Uplink Power Control in Multi-Base Station Mobile Systems
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Solution Overview
Problem
In mobile communication systems where multiple radio base stations receive uplink signals from a radio terminal, traditional transmission power control based on path loss to a single base station can result in excessive power transmission, particularly when a radio terminal is far from a macro base station and near a pico base station.
Innovation Solution
A mobile communication system where at least one radio base station notifies the radio terminal of information specifying all participating radio base stations, allowing the terminal to perform transmission power control based on the smallest path loss or the reciprocal of a sum of path losses among the base stations, thereby avoiding excessive power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transmission power control is performed based on path loss between a single macro base station and the radio terminal, then the uplink signal can be received by the macro base station, but the transmission power becomes excessive when the terminal is near a pico base station
Solution Approach 1:
The invention segments the path loss calculation by identifying multiple base stations (macro and pico) and selecting the appropriate path loss based on the terminal's serving base station. Instead of using a single base station's path loss, the system divides the calculation into separate path losses for different base stations and selects the correct one, thereby avoiding excessive power transmission.
Solution Approach 2:
The invention makes the path loss selection dynamic by allowing the terminal to adaptively choose between different path losses based on which base station is currently serving it. The terminal dynamically switches between using macro base station path loss and pico base station path loss depending on the serving base station, optimizing transmission power in real-time.
2Area of stationary object
If transmission power is increased to ensure reception by all base stations, then coverage is improved, but power consumption increases and interference increases
Solution Approach 1:
The invention applies local quality by using different path loss values appropriate to each base station's characteristics and the terminal's location. Instead of using a uniform path loss for all base stations, the system applies the specific path loss of the serving base station (macro or pico), which is locally optimized for that particular connection, thereby avoiding unnecessary power increase.
3Reliability
If transmission power control uses path loss to the furthest base station, then all base stations can receive the signal, but power efficiency decreases and unnecessary power is consumed
Solution Approach 1:
The invention segments the power control calculation by separating the path loss calculations for different base stations and selecting only the relevant one (the serving base station). This segmentation allows the system to maintain reliable reception by the serving base station without unnecessarily increasing power to reach other base stations, thereby improving power efficiency.
Data Source
AI summary
A mobile communication system is a system in which a plurality of radio base stations receive an uplink signal transmitted from a radio terminal coordinated with one another. At least one radio base station of the plurality of radio base stations comprises: a notification unit that notifies the radio terminal of information for specifying the plurality of radio base stations. The radio terminal comprises a control unit that specifies the plurality of radio base stations on the basis of the information notified from the notification unit, and that performs transmission power control of the uplink signal in accordance with the path losses between each of the plurality of radio base stations and the radio terminal.