Dynamic Transmission Power Allocation in OFDMA Cellular Systems
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Solution Overview
Problem
Existing power allocation schemes in cellular mobile radio systems, such as OFDMA and CDMA, struggle to directly address user demands for bit rate, throughput, and delay, often leading to inefficient resource utilization and slow convergence of transmission power control, especially in multi-cell interference-limited environments.
Innovation Solution
A method and system for dynamic transmission power allocation based on user-measured packet bit rate, packet delay, and buffer size, using a scaling parameter to adjust power increments and decrements, ensuring user performance targets are met while balancing co-channel interference and system throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If existing power allocation schemes are used in multi-cell interference-limited environments, then system complexity is reduced and ease of operation is maintained, but convergence speed of transmission power control is slow and user performance requirements are not directly met
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing power allocation parameters in lookup tables before actual power control operations. The access point pre-processes power allocation based on buffer status indicators and user performance measurements, storing results that can be quickly retrieved and applied during real-time operation. This pre-computation approach enables rapid convergence without requiring complex real-time calculations, directly resolving the contradiction between fast convergence speed and system complexity.
2Productivity
If transmission power is increased to meet user bit rate and throughput requirements, then user performance is improved, but co-channel interference in multi-cell environment increases
Solution Approach 1:
The patent implements local quality by applying differentiated power allocation strategies to different users and different time intervals based on their specific performance requirements and buffer status. Instead of uniform power increase across all users, the system selectively adjusts power for specific user equipment based on measured user performance and buffer status indicators. This localized, user-specific power control achieves the necessary bit rate and throughput for each user while minimizing overall co-channel interference in the multi-cell environment.
Solution Approach 2:
The patent employs feedback mechanisms by continuously measuring user performance metrics (bit rate, throughput, delay) and buffer status, then using this information to dynamically adjust transmission power. The access point receives feedback on user performance and buffer conditions, and adjusts power allocation in response to maintain user requirements while managing interference. This closed-loop feedback approach ensures power is increased only when and where necessary to meet user performance targets, preventing unnecessary interference generation.
3Productivity
If transmission power control adjusts power frequently to meet user performance targets, then user perceived performance is satisfied, but system stability decreases due to rapid power fluctuations
Solution Approach 1:
The patent applies periodic action by adjusting transmission power at regular time intervals based on periodically measured user performance and buffer status, rather than continuously or excessively frequently. The system measures user performance over defined time periods and adjusts power in periodic cycles, which satisfies user performance requirements while avoiding the instability caused by overly frequent power changes. This periodic adjustment rhythm maintains system stability while still responding to user needs.
Solution Approach 2:
The patent implements beforehand cushioning by using buffer status indicators to anticipate future performance needs and pre-adjusting power allocation accordingly. The system monitors buffer fill levels and predicts future user performance requirements, making gradual power adjustments in advance rather than reactive changes. This anticipatory approach cushions against rapid power fluctuations by smoothing transitions and preparing power allocation changes before performance degradation occurs, thereby maintaining both user perceived performance and system stability.
Data Source
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AI summary
The present invention relates to cellular mobile radio systems, and more especially it relates to multi-cell interference-limited environments, such as Orthogonal Frequency Division Multiple Access, OFDMA, and Code Division Multiple Access, CDMA, cellular mobile radio systems. Particularly, it relates to transmission power allocation in such systems. Method and systems where transmission power is based on parameters directly affecting perceived user performance parameters are disclosed.