Ultra Reliable UAV Communication Using Altitude and Cooperation Diversity (1705.02877v1)

Abstract: The use of unmanned aerial vehicles (UAVs) that serve as aerial base stations is expected to become predominant in the next decade. However, in order for this technology to unfold its full potential it is necessary to develop a fundamental understanding of the distinctive features of air-to-ground (A2G) links. As a contribution in this direction, this paper proposes a generic framework for the analysis and optimization of the A2G systems. In contrast to the existing literature, this framework incorporates both height-dependent path loss exponent and small-scale fading, and unifies a widely used ground-to-ground channel model with that of A2G for analysis of large-scale wireless networks. We derive analytical expressions for the optimal UAV height that minimizes the outage probability of a given A2G link. Moreover, our framework allows us to derive a height-dependent closed-form expression and a tight lower bound for the outage probability of an \textit{A2G cooperative communication} network. Our results suggest that the optimal location of the UAVs with respect to the ground nodes does not change by the inclusion of ground relays. This enables interesting insights in the deployment of future A2G networks, as the system reliability could be adjusted dynamically by adding relaying nodes without requiring changes in the position of the corresponding UAVs.

• The paper derives closed-form expressions for optimal UAV altitude to minimize A2G outage probability.
• The study shows that cooperative ground relays can be integrated without altering the optimal UAV positioning.
• Numerical results validate the altitude-dependent model across various transmit power scenarios.

Overview of the Research on Ultra Reliable UAV Communication using Altitude and Cooperation Diversity

The research conducted by Azari et al. extends the understanding of unmanned aerial vehicle (UAV) communication systems, with an emphasis on optimizing air-to-ground (A2G) links for reliable connectivity. The paper proposes a novel framework that integrates the impact of UAV altitude on path loss exponent and small-scale fading, effectively merging traditional ground-to-ground (G2G) channel models with A2G scenarios. This analytical approach allows for the derivation of a height-dependent closed-form expression and a tight lower bound for the outage probability, providing clear implications for designing robust UAV communication networks.

Key Findings

1. Optimal UAV Altitude: The authors derive specific analytical expressions to determine the optimal UAV height that minimizes the outage probability of an A2G link. These expressions offer a reliable method to calculate UAV positioning, which could significantly enhance link reliability.
2. Cooperative Communication Benefits: The framework highlights that the optimal placement of UAVs remains largely unchanged whether ground relays are present or not. This insight simplifies the deployment strategies for A2G networks, as system reliability can be dynamically adjusted by incorporating ground relays without necessitating changes in UAV locations.
3. Numerical Analysis and Model Validation: The paper validates its theoretical findings with numerical data, which aligns closely with simulation results. The paper explores various transmit power scenarios and confirm the viability of the proposed altitude-dependent models.

Implications and Future Directions

The framework extends beyond theoretical developments to practical implications for the deployment of future UAV networks. It enables more effective system design, particularly in urban environments where UAV alignment can be critically important. The revelation that UAV positioning strategies need not be altered with ground relays simplifies system modifications, making deployment more cost-effective and scalable.

Future research may expand on this work by exploring:

• Integration with next-generation network standards (e.g., 5G and beyond) to handle increased A2G traffic.
• The influence of environmental variables, such as varying urban density or extreme weather conditions, on the path loss and fading models.
• Developing more comprehensive frameworks that consider additional cooperative communication techniques and their implications on network capacity and latency.

This work opens avenues for enhanced UAV network design, fostering more reliable, efficient, and adaptive wireless communication systems, especially significant as the telecommunications landscape shifts towards incorporating aerial platforms for broader connectivity solutions. Potential extensions of this research could enrich both theoretical foundations and practical applications, leading to better-integrated and more resilient communication infrastructures.