Token-Based Power Balancing in Cellular Radio Systems
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Solution Overview
Problem
Existing power allocation schemes in multi-cell OFDMA systems fail to balance downlink transmission power effectively, leading to co-channel interference and inefficient resource utilization, as they do not account for instantaneous channel variations and quality requirements across cells.
Innovation Solution
A token-based power balancing method that dynamically assigns or revokes tokens to radio channels based on channel quality or transmission power, inhibiting conventional power control when tokens are revoked, ensuring balanced interference and throughput across cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional power control schemes are used in multi-cell OFDMA systems, then power allocation can be performed based on channel quality indicators, but co-channel interference cannot be effectively balanced across cells with tight frequency reuse
Solution Approach 1:
The patent introduces a central node as an intermediary that coordinates power control across multiple cells. This central node collects CQI reports from all cells, determines appropriate power adjustments considering inter-cell interference, and sends power control commands to access points. This mediator approach enables global optimization of power allocation while balancing co-channel interference across the multi-cell system.
Solution Approach 2:
The patent implements a feedback mechanism where user equipments continuously report channel quality indicators (CQI) to access points, and access points report interference measurements and power usage to the central node. The central node uses this feedback information to dynamically adjust power allocation decisions, creating a closed-loop control system that adapts to changing channel conditions and interference levels.
2Productivity
If downlink transmission power is increased to meet throughput requirements, then channel quality can be maintained, but interference in neighboring cells increases
Solution Approach 1:
The patent dynamically changes the transmission power parameter based on real-time channel conditions and interference measurements. Instead of using fixed power levels, the system adjusts power parameters adaptively by having access points report actual power usage and interference levels to the central node, which then optimizes power allocation to maintain throughput while minimizing interference generation.
Solution Approach 2:
The patent applies different power control strategies to different cells and frequency chunks based on their local conditions. The central node evaluates CQI reports and interference measurements from each cell individually, allowing each cell to have customized power allocation that optimizes its local throughput while considering the impact on neighboring cells, rather than applying uniform power control across the entire system.
3Device complexity
If fixed power allocation is used in the downlink, then power control implementation is simplified, but cell throughput degrades when transmission power does not match channel requirements
Solution Approach 1:
The patent transforms the static fixed power allocation into a dynamic system where power levels adapt to changing channel conditions. Access points continuously monitor downlink channel quality and report to the central node, which then dynamically adjusts power allocation decisions. This dynamic approach maintains simplicity in implementation while significantly improving cell throughput by matching transmission power to actual channel requirements.
4Productivity
If power control is applied in all cells simultaneously, then each cell can optimize its own performance, but global interference balance deteriorates due to lack of coordination
Solution Approach 1:
The central node serves as a coordinating intermediary that collects performance data from all cells, processes this information globally, and sends coordinated power control commands back to each access point. This prevents the uncoordinated simultaneous optimization that would otherwise occur, ensuring that each cell's performance optimization does not degrade the global interference balance.
Solution Approach 2:
The patent merges the individual power control decisions of multiple cells into a unified coordinated control mechanism. By combining CQI reports and interference measurements from all cells and processing them centrally, the system achieves global optimization that balances both individual cell performance and overall network interference, rather than allowing independent uncoordinated control.
Data Source
AI summary
The invention relates to a method of globally balancing the transmit power in a cellular radio system with tight reuse of frequencies, to a central controller node, and to an access point that in combination with conventional power control schemes balances the downlink transmission power on reused frequencies in order to balance co-channel interference in a multi-cell environment. The power balancing scheme dynamically assigns a token to or takes a token away from an individual reused radio channel based on quality of, or based on transmission power in the channel. A token, if taken away from the channel, inhibits conventional power control thereby freezing the transmission power in the channel on its current power level. A token, if assigned or re-assigned to channel, re-assumes conventional power control thereby allowing dynamic variation of the transmission power in the channel in accordance with the conventional power control.