Wireless Power Control for Interference Mitigation
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Solution Overview
Problem
Wireless communication systems face interference issues due to incomplete orthogonality among multiple-access transmissions, leading to degraded performance from intra-sector and inter-sector interference, necessitating effective power control techniques to maintain acceptable interference levels.
Innovation Solution
The proposed solution involves adjusting the transmit power of wireless terminals based on observed interference, channel gains, and proximity to base stations, using probabilistic or deterministic methods to maintain intra-sector and inter-sector interference within acceptable limits by controlling the signal-to-noise ratio (SNR) range for data channels, and utilizing OSI bits broadcast by base stations to guide power adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple terminals transmit simultaneously on the reverse link using multiplexing, then system capacity and throughput are improved, but interference from incomplete orthogonality degrades performance
Solution Approach 1:
The patent dynamically adjusts transmit power parameters for different terminals based on their channel conditions and interference levels. By changing the power parameter adaptively, the system maintains high capacity while controlling interference effects through probabilistic power adjustment strategies.
Solution Approach 2:
The patent implements a feedback mechanism where terminals report channel quality and interference measurements to the base station. The base station uses this feedback to adjust power allocation and multiplexing decisions, creating a closed-loop system that balances capacity and interference control.
2Reliability
If transmit power is increased to improve signal quality, then SNR and data rate are improved, but interference to other terminals increases
Solution Approach 1:
The patent applies different power levels to different terminals based on their local channel conditions. Terminals with better channel conditions receive higher power allocations, while terminals causing more interference receive lower allocations. This localized quality adjustment optimizes overall system performance by matching power distribution to actual needs.
Solution Approach 2:
The patent uses dynamic power adjustment where transmit power levels are not fixed but change adaptively based on real-time channel conditions and interference measurements. This dynamic approach allows the system to respond to changing conditions and maintain optimal signal quality while minimizing interference.
3Object-affected harmful factors
If orthogonal multiplexing is used to separate transmissions, then interference is reduced, but complete orthogonality cannot be achieved due to channel conditions and receiver imperfections
Solution Approach 1:
The patent accepts that complete orthogonality cannot be achieved and instead aims for partial orthogonality sufficient to control interference at acceptable levels. Rather than pursuing perfect separation, the system uses power control to compensate for the incomplete orthogonality, achieving practical interference management without requiring perfect multiplexing separation.
Data Source
AI summary
Techniques for adjusting transmit power to mitigate both intra-sector interference to a serving base station and inter-sector interference to neighbor base stations are described. The amount of inter-sector interference that a terminal may cause may be roughly estimated based on the total interference observed by each neighbor base station, channel gains for the serving and neighbor base stations, and the current transmit power level. The transmit power may be decreased if high interference is observed by a neighbor base station and increased otherwise. The transmit power may be adjusted by a larger amount and/or more frequently if the terminal is located closer to the neighbor base station observing high interference and/or if the current transmit power level is higher, and vice versa. The intra-sector interference is maintained within an acceptable level by limiting a received SNR for the terminal to be within a range of allowable SNRs.