D2D Interference Mitigation via Spatial Alignment
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Solution Overview
Problem
In device-to-device (D2D) communications within LTE networks, managing interference between D2D transmissions and cellular user communications is challenging, especially when shared resources are non-orthogonal, leading to increased interference as the distance between D2D devices grows, complicating power control methods.
Innovation Solution
The implementation of opportunistic interference alignment and clustering techniques, where the base station selectively allows D2D transmissions based on spatial decoding to mitigate interference, using either centralized or distributed admission control, and base-station aided space-time interference alignment to overhear and forward interference patterns, allowing D2D receivers to cancel inter-D2D link interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If D2D transmissions use the same licensed band as LTE network, then spatial reuse and throughput are improved, but interference management becomes significantly more difficult
Solution Approach 1:
The base station acts as an intermediary that receives channel state information from both cellular UEs and D2D devices, computes spatial decoders, and provides feedback to D2D transmitters. This centralized coordination mechanism enables interference mitigation through base-station aided space-time interference alignment, resolving the complexity of direct D2D interference management.
Solution Approach 2:
The system changes spatial parameters by computing and applying spatial decoders that transform the signal reception process. The base station computes spatial decoders based on channel state information and provides feedback to D2D transmitters, enabling dynamic adaptation of spatial parameters to mitigate interference while maintaining spectral efficiency.
2Object-affected harmful factors
If power control is used to reduce D2D interference, then interference to cellular users is reduced, but the effectiveness decreases as distance between D2D devices increases
Solution Approach 1:
The patent replaces traditional power control mechanisms with spatial processing techniques. Instead of relying solely on power adjustment, the system uses base station computed spatial decoders and feedback to enable D2D transmitters to adjust their transmission spatial characteristics, providing more effective interference control especially for long-distance D2D communications.
Solution Approach 2:
The base station serves as a mediator that collects channel state information, computes optimal spatial decoders, and provides feedback to D2D transmitters. This intermediary coordination enables sophisticated interference management that overcomes the limitations of simple power control, particularly for distant D2D device pairs.
3Quantity of substance
If non-orthogonal resources are shared between D2D communications and cellular network, then resource efficiency is improved, but interference between D2D and cellular transmissions increases
Solution Approach 1:
The patent moves the interference mitigation problem from the time-frequency domain to the spatial domain. By computing and applying spatial decoders at the base station and providing feedback to D2D transmitters, the system exploits the spatial dimension to separate D2D and cellular transmissions, enabling non-orthogonal resource sharing without excessive interference.
Solution Approach 2:
The system dynamically changes spatial parameters through base station computed decoders and feedback mechanisms. This enables adaptive resource allocation where D2D and cellular transmissions can share non-orthogonal time-frequency resources while maintaining acceptable interference levels through spatial processing.
Data Source
AI summary
Described are techniques for managing the interference produced by D2D (device-to-device) transmissions that may be used in conjunction with transmit power control but operate independently. In one technique, interference between D2D transmissions and cellular uplink transmissions using common resources as received at a base station is managed by opportunistic interference alignment and clustering of D2D devices. In another technique, interference between different D2D devices using the same resources is mitigated by base-station aided space-time interference alignment.