Uplink Power Control via Bandwidth and Frequency Allocation
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Solution Overview
Problem
In LTE mobile communication systems, the limitation of maximum transmission power at mobile stations often results in difficulty in achieving the required Signal-to-Interference Ratio (SIR) at the radio base station, especially at cell edges, leading to interference issues between adjacent cells when attempting to compensate for path loss by reducing transmission bandwidth.
Innovation Solution
A radio base station with a power estimate unit, transmission format determination unit, and transmission instruction unit that estimates the transmission power of uplink signals, determines the transmission bandwidth and frequency based on estimated power values and predetermined conditions, and instructs mobile stations to adjust their transmission formats to minimize interference by optimizing bandwidth and frequency allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transmission power of the mobile station is increased to compensate for path loss at cell edge, then the required SIR at the reception end can be realized, but the transmission power exceeds the maximum allowed power limit
Solution Approach 1:
The patent changes the transmission bandwidth parameter to resolve the power contradiction. By reducing the transmission bandwidth, the signal power density increases, which improves the SIR at the reception end without requiring higher transmission power. This allows cell edge users to achieve required SIR while staying within maximum power limits.
2Reliability
If the transmission bandwidth is decreased to improve SIR at the reception end, then the required SIR can be realized, but interference between adjacent cells increases
Solution Approach 1:
The patent applies preliminary action by determining the transmission frequency before assigning resource blocks. The base station calculates a target frequency based on the mobile station's current frequency and path loss, then uses this pre-determined frequency to select appropriate resource blocks. This prevents interference between adjacent cells while maintaining the bandwidth reduction benefits for improved SIR.
Solution Approach 2:
The patent introduces an intermediary mechanism - the base station's frequency determination unit - that mediates between the mobile station's transmission needs and the network's interference management requirements. This intermediary calculates optimal frequencies and coordinates resource block assignments to balance SIR improvement with interference reduction.
3Object-generated harmful factors
If the transmission frequency is changed to reduce interference between cells, then interference can be minimized, but the transmission power may exceed maximum limits
Solution Approach 1:
The patent performs preliminary frequency determination based on path loss calculations before power allocation. By pre-calculating the target frequency and determining appropriate resource blocks, the system ensures that frequency changes are coordinated with power management, preventing power exceedance while achieving interference reduction.
Data Source
AI summary
A radio base station includes a power estimate unit configured to estimate a transmission power of an uplink signal in a mobile station (UE), a transmission format determination unit configured to determine a transmission bandwidth and a transmission frequency of the uplink signal as a transmission format of the uplink signal transmitted by the mobile station (UE), and a transmission instruction unit configured to instruct the mobile station (UE) to transmit the uplink signal by using the determined transmission format. The transmission format determination unit is configured to determine the transmission bandwidth of the uplink signal based on an estimation value of the transmission power, and to determine the transmission frequency of the uplink signal based on information relating to a cell with which the mobile station communicates.