TDD Small-Cell Power Control for Adjacent-Channel Interference
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Solution Overview
Problem
In broadband wireless communications networks with time division duplexing (TDD), adjacent cells with different TDD configurations can experience mutual interference due to opposite transmission directions during certain sub-frames, particularly between macrocells and small cells using adjacent frequency channels.
Innovation Solution
Adjusting the transmit powers of transmissions in small cells and introducing an adjacent channel association bias to mitigate interference, allowing dynamic TDD configuration selection based on traffic conditions and reducing interference by optimizing power levels during incongruent sub-frames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different TDD configurations are used in macrocell and small cell to adapt to traffic conditions, then adaptability is improved, but interference between adjacent cells increases
Solution Approach 1:
The patent applies local quality by configuring different TDD uplink-downlink patterns for macrocell and small cell based on their specific traffic conditions. The small cell can dynamically select TDD configurations that match its local traffic demands while the macrocell maintains its configuration, creating localized optimization without requiring network-wide uniformity. This resolves the contradiction by allowing adaptability at the local cell level while managing interference through targeted power control in the overlapping region.
Solution Approach 2:
The patent changes the transmit power parameter dynamically based on the TDD configuration mismatch between macrocell and small cell. When incongruent sub-frames are detected (where macrocell is in downlink and small cell is in uplink, or vice versa), the transmit power is adjusted to reduce interference. This parameter change approach allows the system to maintain different TDD configurations for adaptability while controlling interference through real-time power adjustment.
2Area of stationary object
If transmit power is increased in small cell to improve coverage, then coverage area is improved, but interference with macrocell uplink increases
Solution Approach 1:
The patent implements dynamics by making the transmit power adjustable and time-varying rather than fixed. The small cell's transmit power is dynamically controlled based on the TDD configuration state and detected interference conditions. During incongruent sub-frames where interference occurs, the power is reduced; during congruent sub-frames or when interference is low, power can be increased to expand coverage. This dynamic approach resolves the contradiction between coverage area and interference.
3Object-affected harmful factors
If transmit power is reduced to minimize interference, then interference is reduced, but coverage area and signal strength decrease
Solution Approach 1:
The patent applies periodic action by controlling transmit power in a time-varying manner that follows the TDD frame structure. Power is periodically adjusted based on whether the current sub-frame is congruent or incongruent between macrocell and small cell TDD configurations. During incongruent sub-frames, power is reduced to minimize interference; during congruent sub-frames, power is increased to maintain coverage. This periodic power adjustment resolves the contradiction by providing both low interference and adequate coverage at different time intervals.
Data Source
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AI summary
Techniques for adjacent channel interference mitigation are described. In one embodiment, for example, a user equipment (UE) may comprise logic, at least a portion of which is in hardware, the logic to associate the UE with a pico evolved node B (eNB) in a time-division duplex (TDD) picocell, identify an incongruent uplink (UL) sub-frame for the picocell, and select an enhanced UL transmit power for the incongruent UL sub-frame. Other embodiments are described and claimed.