Mahdi Asadpour

Application-driven design of aerial communication networks

Networks of micro aerial vehicles (MAVs) equipped with various sensors are increasingly used for civil applications, such as monitoring, surveillance, and disaster management. In this article, we discuss the communication requirements raised by applications in MAV networks. We propose a novel system representation that can be used to specify different application demands. To this end, we extract key functionalities expected in an MAV network. We map these functionalities into building blocks to characterize the expected communication needs. Based on insights from our own and related real-world experiments, we discuss the capabilities of existing communications technologies and their limitations to implement the proposed building blocks. Our findings indicate that while certain requirements of MAV applications are met with available technologies, further research and development is needed to address the scalability, heterogeneity, safety, quality of service, and security aspects of multi- MAV systems.

Micro aerial vehicle networks: an experimental analysis of challenges and opportunities

The need for aerial networks is growing with the recent advance of micro aerial vehicles, which enable a wide range of civilian applications. Our experimental analysis shows that wireless connectivity among MAVs is challenged by the mobility and heterogeneity of the nodes, lightweight antenna design, body blockage, constrained embedded resources, and limited battery power. However, the movement and location of MAVs are known and may be controlled to establish wireless links with the best transmission opportunities in time and space. This special ecosystem undoubtedly requires a rethinking of wireless communications and calls for novel networking approaches. Supported by empirical results, we identify important research questions, and introduce potential solutions and directions for investigation.

Characterizing 802.11n aerial communication

In Search And Rescue missions, Unmanned Aerial Vehicles (UAVs) equipped with cameras allow for efficient scanning of large areas. Yet, delivering high resolution images to rescuers also requires high-speed communication. In this paper, we investigate the potential and challenges of wireless communication between UAVs in such scenarios. Our fleet of UAVs supports both a high-bandwidth network for bulk data transfer (802.11n) as well as a long-range radio for control messages (XBee-PRO 802.15.4). Extensive experiments show that 802.11n performs poorly in highly mobile scenarios, as the throughput between UAVs drops far below the theoretical maximum as soon as they become airborne. We consider several potential causes and present an analysis of their impact in isolation.

A Privacy-Friendly RFID Protocol Using Reusable Anonymous Tickets

A majority of the existing privacy-friendly RFID protocols use the output of a cryptographic hash function in place of real identity of an RFID tag to ensure anonymity and untraceability. In order to provide unique identification for the tags, these protocols assume that the hash functions are collision resistant. We show that, under this assumption on the hash functions, a substantial number of the existing protocols suffer from a trace ability problem that causes differentiating a tag from another. We propose a scalable privacy-friendly RFID protocol and describe its design and implementation issues. Our protocol substitutes the hash functions used for identification with anonymous tickets, thus avoiding the aforementioned trace ability problem. The anonymous tickets are reusable. They nevertheless identify the tags uniquely, at any given point in time. The query and search algorithm of our proposed protocol is of O(1) time complexity, and it imposes small storage overhead on the back-end database. We show that the protocol is scalable, and compare its storage and computational requirements to some existing protocols. We formally prove the security requirements of our protocol, and mechanically analyze some of its requirements using the model checker OFMC.

Now or later?: delaying data transfer in time-critical aerial communication

Search and rescue missions are entering a new era with the advent of small scale unmanned aerial vehicles (UAVs) with communication capabilities and embedded cameras. Yet, delivering high resolution images of the supervised surface to rescuers is time-critical. To help resolving this problem, we study how UAVs can take advantage of their controlled mobility to derive the optimum strategy for data transmission. Driven by real-world aerial experiments with both airplanes and quadrocopters equipped with 802.11n technology, we show that the UAV should not necessarily transmit as soon as a wireless link is established. Instead, it should wait until it reaches a suitable distance to the receiving UAV, only to transmit when the time to move to the new location and transmit is minimal. We then apply the principle of delayed gratification, where the UAV attempts to solve the tradeoff between postponing until it reaches this minimum and the impatience to deliver as much data as soon as possible, before any physical damage on-the-fly may occur. Our empirical-driven simulations demonstrate that the optimal distance of transmission greatly depends on the interplay of actual throughput, data size, UAV cruise speed, and failure rate, and that state-of-the-art UAVs can already benefit from our approach.

From ground to aerial communication: dissecting WLAN 802.11n for the drones

Micro Unmanned Aerial Vehicles (UAVs) employed in civil missions are receiving remarkable attention from both research and industry. UAVs embed more and more sensor technology, and their small mounted cameras allow for efficient mapping of large areas in short time. Yet, civil missions such as rescue operations would need a timely delivery of high-resolution images, which calls for high-speed communication such as provided by WLAN IEEE 802.11n. Driven by extensive experiments, the key finding of this contribution is that 802.11n performs poorly in highly mobile and aerial scenarios, as the throughput between UAVs drops far below the theoretical maximum as soon as they become airborne. This is partially caused by the limitations of the embedded hardware, but also a result of the network dynamics of the aerial links. In order to dissect the origins of the low performance figures, we isolate the potential causes of degradation by analyzing our data of throughput, packet loss, aircraft and antenna orientation, and cruise speed. We discuss quantitatively how practical it is to deliver high-resolution images when being exposed to aerial throughput. We believe that it will be a long way until micro UAVs transferring large-size data become reality and argue for a new amendment of IEEE 802.11 addressing the communication among highly-mobile UAVs.

Route or Carry: Motion-Driven Packet Forwarding in Micro Aerial Vehicle Networks

Micro aerial vehicles (MAVs) provide data such as images and videos from an aerial perspective, with data typically transferred to the ground. To establish connectivity in larger areas, a fleet of MAVs may set up an ad-hoc wireless network. Packet forwarding in aerial networks is challenged by unstable link quality and intermittent connectivity caused by MAV movement. We show that signal obstruction by the MAV frame can be alleviated by adapting the MAV platform, even for low-priced MAVs, and the aerial link can be properly characterized by its geographical distance. Based on this link characterization and making use of GPS and inertial sensors on-board of MAVs, we design and implement a motion-driven packet forwarding algorithm. The algorithm unites location-aware end-to-end routing and delay-tolerant forwarding, extended by two predictive heuristics. Given the current location, speed, and orientation of the MAVs, future locations are estimated and used to refine packet forwarding decisions. We study the forwarding algorithm in a field measurement campaign with quadcopters connected over Wi-Fi IEEE 802.11n, complemented by simulation. Our analysis confirms that the proposed algorithm masters intermittent connectivity well, but also discloses inefficiencies of location-aware forwarding. By anticipating motion, such inefficiencies can be counteracted and the forwarding performance can be improved.

Routing in a fleet of micro aerial vehicles: first experimental insights

Micro aerial vehicles (MAVs) have the potential to support civilian applications in large areas by providing an ad-hoc multi-hop wireless network. Yet, available network routing protocols have not been designed for the micro aerial use case and it is unclear how well they can cope in practice with the wireless link and topology dynamics posed by MAVs. To answer this question, we provide a first assessment of major ad-hoc routing protocols in a lab study. Further, we present measurement results for B.A.T.M.A.N. and greedy geographical routing in a small IEEE 802.11n MAV testbed and discuss potential directions for future research.

UAV networks in rescue missions

Small-scale unmanned aerial vehicles (UAVs) have received high attention by the robotics community for delivering sensory data of limited size. Yet, the communication capabilities of off-the-shelf UAVs are insufficient for high volume data, such as images and videos. In this demo, we present our networking solution to this problem, residing next to the auto-pilot, and able to create an ad-hoc multi-hop network of UAVs. We show the effectiveness of our implementation in two representative scenarios of rescue missions: [(i)] the establishment of end-to-end connectivity for a smartphone in an area with network outage and the delivery of a high-resolution video of a supervised area from a flying UAV to the ground station.

Scalable, privacy preserving radio-frequency identification protocol for the internet of things

It is now possible to embed radio‐frequency identification tags into almost any physical device. However, issues regarding privacy remain a concern and limit their widespread use. We propose a scalable anonymous radio‐frequency identification authentication protocol using what we refer to as anonymous tickets. These tickets uniquely identify tags and are reusable. This considerably strengthens its non‐traceability and requires just O(1) search/query time, with minimal storage overhead on the back‐end system. We formally prove the protocol and compare the performance of the proposed protocol with selected works found in literature. Copyright