Reverse Link Power Control for Wireless Systems
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Solution Overview
Problem
Wireless communication systems face interference issues due to non-orthogonal transmissions from multiple terminals, leading to degraded performance, as existing power control techniques fail to effectively mitigate intra-sector and inter-sector interference.
Innovation Solution
Terminals adjust their transmit power based on feedback and interference information, such as rise over thermal ratio (RoT) or interference over thermal ratio (IoT), received from sectors, to minimize interference and optimize performance for both CDMA and OFDMA channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple terminals transmit simultaneously on the reverse link, then system capacity and communication service coverage are improved, but interference between terminals increases due to non-orthogonal transmissions
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the transmit power levels of terminals based on real-time interference conditions. The base station measures interference metrics (such as rise over thermal ratio) and sends power control commands to terminals, which then modify their transmit power parameters accordingly. This allows the system to maintain high capacity while controlling interference through continuous parameter optimization.
Solution Approach 2:
The patent implements a feedback mechanism where the base station continuously monitors interference levels on the reverse link and sends power control commands back to terminals. The base station measures metrics such as the rise over thermal ratio (RoT) and uses this feedback information to adjust terminal transmit powers. This closed-loop feedback system enables dynamic interference management while maintaining system capacity.
2Reliability
If transmit power of terminals is increased to improve signal quality, then reception performance is improved, but interference to other terminals and base stations increases
Solution Approach 1:
The patent uses parameter changes to dynamically adjust terminal transmit power based on measured interference conditions. Instead of using fixed high power levels, the system continuously modifies power parameters according to real-time base station measurements of interference metrics, achieving optimal reception performance while minimizing interference to other users.
Solution Approach 2:
The patent implements feedback-based power control where the base station measures reception quality and interference levels, then sends power control commands to terminals. This feedback loop allows the system to increase power when reception performance is poor while automatically reducing power when interference levels become excessive, balancing reliability and interference control.
3Object-generated harmful factors
If power control techniques are implemented to reduce interference, then interference mitigation is improved, but system complexity increases due to additional signaling and measurements
Solution Approach 1:
The patent applies self-service by having terminals autonomously adjust their transmit power based on simple power control commands from the base station, rather than requiring complex distributed interference coordination between multiple base stations. Each terminal independently responds to base station commands, simplifying the overall system architecture while achieving effective interference mitigation.
Data Source
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AI summary
Techniques for controlling transmit power of a terminal are described. The terminal may send a first transmission (e.g., for pilot or signaling) on the reverse link, receive feedback (e.g., a power control command or an erasure indicator) for the first transmission, and adjust a reference power level based on the feedback. The terminal may also receive interference information and possibly other parameters such as a pilot quality indicator (PQI), an offset factor, and a boost factor from a sector. The terminal may determine transmit power for a second transmission to the sector based on the interference information, the reference power level, and/or the other parameters. The terminal may receive the feedback from one sector and may send the second transmission with CDMA or OFDMA to the same sector or a different sector.