Mobile Station Power Control for Soft Handover Signal Quality
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Solution Overview
Problem
In cellular systems, the existing methods for controlling transmission power during soft handover lead to a slow response to signal quality variations, resulting in a high probability of erroneous power control and a deterioration in the receiving quality of acknowledge/non-acknowledge signals, particularly for packet-transmitting base stations.
Innovation Solution
A novel cellular system that employs a dual transmission power control mechanism, where a mobile station activates a second power control function when receiving packets, adjusting the transmission power based on specific information from the packet-transmitting base station to rapidly reach a target signal-to-interference ratio, thereby improving the quality of control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a mobile station continuously sets the dedicated physical channel to the base station during stand-by state, then the data transmission can commence promptly upon receipt of a request, but the transmission power control response becomes slow due to receiving power control signals from multiple link base stations
Solution Approach 1:
The patent segments the power control signal reception into two distinct modes: during packet reception, the mobile station receives power control signals only from the packet-transmitting base station; during non-packet reception, it receives signals from all link base stations. This segmentation resolves the contradiction by isolating the fast-response power control path from the multi-base-station coordination path.
Solution Approach 2:
The mobile station dynamically switches between two power control reception modes based on whether it is receiving a packet. When in packet reception state, it activates the first power control function for rapid response; otherwise, it uses the second power control function for coordinated control. This dynamic adaptation allows the system to optimize response speed according to operational context.
2Reliability
If the mobile station receives power control signals from all link base stations, then the power control coordination is maintained, but the receiving quality of acknowledge/non-acknowledge signals deteriorates due to slow power adjustment response
Solution Approach 1:
The patent divides power control signal reception into two segmented paths: one for packet-transmitting base stations (prioritizing signal quality) and another for other link base stations (maintaining coordination). During packet reception, only the packet-transmitting base station's power control signals are processed, ensuring high receive signal quality while maintaining overall system coordination through the alternative path.
Solution Approach 2:
The mobile station acts as an intermediary that selectively processes power control signals based on reception state. It mediates between the need for coordinated power control from all base stations and the need for rapid, high-quality power control from the packet-transmitting base station by activating appropriate processing functions based on current operational state.
3Measurement precision
If the transmission power is increased rapidly to reach target signal-to-interference ratio, then the receive signal quality improves, but the interference to other cells increases
Solution Approach 1:
The patent applies local quality by differentiating power control processing based on the source base station. Power control signals from the packet-transmitting base station receive prioritized processing to ensure high receive signal quality, while power control signals from other link base stations are processed separately to maintain coordination without causing excessive interference. This localized differentiation allows optimized power control for critical communications while controlling overall interference.
Data Source
AI summary
In a cellular system, each mobile station concurrently linked to plural link base stations in soft handover state and receiving packet from the packet-transmitting base station controls a transmission power of an up-link dedicated physical channel based on a first transmission power control information included in down-link dedicated physical channels of the link base stations. In other state, the mobile station controls the transmission power based on a second transmission power control information included in a down-link dedicated physical channel of the packet-transmitting base station. This accelerates the power increase up to a target power level causing that the measured signal-to-interference-ratio at the packet-transmitting base station reaches a target signal-to-interference-ratio, thereby improving receiving quality of control signal from the mobile station at the packet-transmitting base station.