Uplink Power Control via Interference Feedback
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Solution Overview
Problem
In cellular communication systems, uplink transmission quality is degraded due to interference from terminals connected to a single base station, as neighbor base stations cannot reduce transmission power of interfering terminals, leading to significant quality degradation in non-soft handover scenarios.
Innovation Solution
The method involves the serving base station selecting groups of terminals to stop transmission temporarily, allowing others to measure and estimate interference on neighboring cells, and adjusting uplink transmission power to limit interference within predefined levels, either autonomously by terminals or through network evaluation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If terminals transmit at high power to improve uplink coverage, then signal strength increases, but interference to neighboring cells increases
Solution Approach 1:
The patent implements a feedback mechanism where the serving base station receives interference measurements from neighboring base stations and uses this information to adjust uplink transmission power limits for terminals. The neighboring base stations measure the uplink interference caused by terminals and send this information back to the serving base station, which then sends resource indications to control terminal transmission power, creating a closed-loop feedback system that dynamically balances signal strength and interference.
Solution Approach 2:
The patent applies preliminary action by having the serving base station proactively send resource indications to terminals before they transmit, setting maximum transmission power limits based on predicted interference conditions. The base station calculates the maximum allowed transmission power taking into account the terminal's distance to the serving base station and the distance to neighboring base stations, preventing interference before it occurs rather than reacting to it afterward.
2Ease of operation
If a single base station controls uplink scheduling for its terminals, then intra-cell interference is managed, but inter-cell interference from neighboring cells cannot be controlled
Solution Approach 1:
The patent introduces an intermediary mechanism where neighboring base stations act as observers and measurement points for interference caused by terminals. The serving base station uses information from these intermediary neighboring base stations to make informed scheduling decisions. The neighboring base stations measure the interference they receive from terminals and provide this data back to the serving base station, enabling indirect control of inter-cell interference while maintaining the simplicity of single-base-station scheduling.
3Object-generated harmful factors
If terminals are forced to stop transmission to reduce interference, then interference to neighboring cells decreases, but uplink resource utilization decreases
Solution Approach 1:
The patent applies dynamics by making transmission power limits dynamic rather than static. The resource indications sent to terminals are continuously adjusted based on current interference conditions measured by neighboring base stations. When interference is high, transmission power limits are reduced; when interference is low or terminals are far from neighboring cells, limits are increased. This dynamic adjustment ensures that uplink resources are utilized as much as possible while maintaining interference control.
Solution Approach 2:
The patent changes the parameter of transmission power limits based on spatial and interference conditions. The serving base station calculates maximum allowed transmission power by considering the terminal's distance to the serving base station and the distance to neighboring base stations. This parameter adjustment allows terminals closer to the serving base station and farther from neighboring cells to transmit at higher powers, maximizing resource utilization while controlling interference through mathematically optimized power limits.
Data Source
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AI summary
The invention relates to a method for uplink transmission interference limitation in a wireless communications system comprising a mobile network (N) arranged in a radio cell configuration, each cell (C1, C2) comprising a serving base station (B1, B2) providing communications service to at least one user terminal (a1, d1 to d3) inside the cell area, the method comprising the steps of (100) selecting and forcing a first group of cell-associated terminals to stop transmission for a certain period of time (MP); (102) selecting a second group of terminals for measuring the signal power present at their uplink transmission frequency; (104, 104') calculating an indication of the interference (I) level generated by at least the second group of selected terminals in at least one neighbouring cell; (106, 1 O6') selecting a third group of cell-associated terminals and setting their uplink transmission power (P) to a certain value (P2, P3) according to the calculated interference (I) level.