Multi-tier Drone Architecture for 5G/B5G Cellular Networks: Challenges, Trends, and Prospects (1711.08407v1)

Abstract: Drones (or unmanned aerial vehicles [UAVs]) are expected to be an important component of fifth generation (5G)/beyond 5G (B5G) cellular architectures that can potentially facilitate wireless broadcast or point-to-multipoint transmissions. The distinct features of various drones such as the maximum operational altitude, communication, coverage, computation, and endurance impel the use of a multi-tier architecture for future drone-cell networks. In this context, this article focuses on investigating the feasibility of multi-tier drone network architecture over traditional single-tier drone networks and identifying the scenarios in which drone networks can potentially complement the traditional RF-based terrestrial networks. We first identify the challenges associated with multi-tier drone networks as well as drone-assisted cellular networks. We then review the existing state-of-the-art innovations in drone networks and drone-assisted cellular networks. We then investigate the performance of a multi-tier drone network in terms of spectral efficiency of downlink transmission while illustrating the optimal intensity and altitude of drones in different tiers numerically. Our results demonstrate the specific network load conditions (i.e., ratio of user intensity and base station intensity) where deployment of drones can be beneficial (in terms of spectral efficiency of downlink transmission) for conventional terrestrial cellular networks.

• The paper presents a novel multi-tier UAV framework that significantly improves spectral efficiency in 5G/B5G networks.
• It analyzes the deployment of low and high altitude drones to optimize network capacity and manage interference effectively.
• The study highlights practical challenges such as energy constraints and regulatory hurdles, guiding future research directions.

Multi-tier Drone Architecture for 5G/B5G Cellular Networks: Challenges, Trends, and Prospects

The paper "Multi-tier Drone Architecture for 5G/B5G Cellular Networks: Challenges, Trends, and Prospects" by Silvia Sekander, Hina Tabassum, and Ekram Hossain presents a focused analysis on the implications, benefits, and challenges of integrating UAVs in a multi-tier framework within 5G/B5G cellular networks. Drones are increasingly seen as viable components or supplements to terrestrial cellular infrastructures, particularly in scenarios characterized by severe shadowing, high interference, overloaded networks, or when rapid deployment is essential.

Key Contributions and Findings

The paper carefully delineates a multi-tier UAV framework, contrasting it against a single-tier drone network, and investigates the spectral efficiency ramifications of such an architecture. A multi-tier approach leverages different types of drones—categorized by their size, weight, and power (SWAP) constraints—across varying operational altitudes. These UAVs are classified into low altitude platforms (LAPs) and high altitude platforms (HAPs), each with distinct operational benefits and constraints. For instance, LAPs enable rapid deployment and cost-effectiveness, albeit at the cost of limited payload and operational endurance, while HAPs offer extended coverage and endurance at higher altitudes.

Numerical investigations reveal that the strategic deployment of diverse UAV types within a multi-tier framework yields excellent spectral efficiency benefits compared to traditional terrestrial networks. In particular scenarios characterized by high user-to-base station ratios, multi-tier drone architectures significantly enhance the overall network capacity by complementing existing cellular infrastructures.

Challenges

Executing a multi-tier drone network model encounters several challenges, notably including:

1. Interference Management: The introduction of UAVs in cellular networks necessitates meticulous interference control, particularly in scenarios where multiple drone tiers and terrestrial networks coexist. Strategies such as spectrum optimization and spatio-temporal allocation will be pivotal.
2. Energy Efficiency: Addressing the UAVs' power consumption, specifically in maintaining optimal operational altitudes and mobility paths, needs efficient management to ensure sustainable deployments.
3. Regulatory and Cost Barriers: The regulatory landscape concerning drone operations remains limited, especially concerning coordination without fixed backhaul support. Moreover, the high initial costs and potential security risks related to UAVs must be considered.
4. Trajectory and Mobility Planning: Optimal path planning for drones, balancing coverage and resource utilization, remains a complex task particularly in diverse environmental settings.

Implications and Future Directions

The integration of multi-tier drone systems provides compelling prospects for versatile, adaptive, and efficient wireless communication networks, offering resilient network responses to disaster zones and easing urban network congestion. This paper lays the groundwork for future developments including:

• Hybrid spectrum strategies that exploit both licensed and unlicensed spectrum, thus broadening operational bandwidth.
• Advanced energy harvesting mechanisms to bolster the endurance of LAPs and HAPs, reducing reliance on traditional power sources.
• Adaptive deployment strategies that dynamically adjust drone densities and altitudes in response to real-time network conditions and environmental factors.

As 5G and beyond technologies continue to evolve, the inclusion of multi-tier drone networks holds the potential to dramatically transform the landscape of wireless communications, enabling more robust, agile, and efficient network architectures. The paper's insights into spectral efficiency optimization through UAV deployment provide a strategic avenue for achieving significant advancements in cellular network capacities and performances. Future research could explore the economic aspects of drone integration, potential swarming strategies for coordinated UAV operations, and the implications of 3D aerial traffic management on cellular connectivity dynamics.