The days where swarms of unmanned aerial vehicles (UAVs) will occupy our skies are fast approaching due to the introduction of cost-efficient and reliable small aerial vehicles and the increasing demand for use of such vehicles in a plethora of civil applications. Governments and industry alike have been heavily investing in the development of UAVs. As such it is important to understand the characteristics of networks with UAVs to enable the incorporation of multiple, coordinated aerial vehicles into the air traffic in a reliable and safe manner. To this end, this survey reports the characteristics and requirements of UAV networks for envisioned civil applications over the period 2000–2015 from a communications and networking viewpoint. We survey and quantify quality-of-service requirements, network-relevant mission parameters, data requirements, and the minimum data to be transmitted over the network. Furthermore, we elaborate on general networking related requirements such as connectivity, adaptability, safety, privacy, security, and scalability. We also report experimental results from many projects and investigate the suitability of existing communication technologies for supporting reliable aerial networking.

Survey on Unmanned Aerial Vehicle Networks for Civil Applications: A Communications Viewpoint

Individuals share music through portable audio devices (100) that synchronously play music by transmitting music signals from one device (unit A) to the other (unit B). Upon request, other individuals can join such a sharing group as a member, and these new members can either be accepted automatically, or through voting by existing group members. So that members of a group can converse, the fraction of ambient sound admitted by the earphones of the portable device (100) can be manually set. In order to enhance the enjoyment of the music, wearable transducers (240, 250, 260), such as light emitting diodes, respond to signals related to the beat of the music. Signals can be automatically generated, or manually specified, and signals thereafter stored for playback with the music to which it is related. Wearable transducers associated with individuals at a large music event can be set to receive common signals such that the transducers (240, 250, 260) respond in synchrony with one another.

Localized audio networks and associated digital accessories

The present invention discloses a method, system and apparatus for playing an audio signal synchronously on a first mobile audio player and at least a second mobile audio player. More particularly, the invention pertains to an audio player device enabled for wireless transmission and reception of an audio signal. In one aspect, a delay enables the audio signal to be played synchronously on the audio player with a second audio player. In another aspect synchronization signals are used to play the audio signal synchronously on the first audio player and the second audio player.

Audio player device for synchronous playback of audio signals with a compatible device

In this paper, we investigate a communication system in which unmanned aerial vehicles (UAVs) are used as relays between ground-based terminals and a network base station. We develop an algorithm for optimizing the performance of the ground-to-relay links through control of the UAV heading angle. To quantify link performance, we define the ergodic normalized transmission rate (ENTR) for the links between the ground nodes and the relay, and derive a closed-form expression for it in terms of the eigenvalues of the channel correlation matrix. We show that the ENTR can be approximated as a sinusoid with an offset that depends on the heading of the UAV. Using this observation, we develop a closed-form expression for the UAV heading that maximizes the uplink network data rate while keeping the rate of each individual link above a certain threshold. When the current UAV relay assignments cannot meet the minimum link requirements, we investigate the deployment and heading control problem for new UAV relays as they are added to the network, and propose a smart handoff algorithm that updates node and relay assignments as the topology of the network evolves.

/pdf/wireless-relay-communications-with-unmanned-aerial-vehicles-24bmthm3qf.pdf

Wireless Relay Communications with Unmanned Aerial Vehicles: Performance and Optimization

In recent years, the capabilities and roles of Unmanned Aerial Vehicles (UAVs) have rapidly evolved, and their usage in military and civilian areas is extremely popular as a result of the advances in technology of robotic systems such as processors, sensors, communications, and networking technologies. While this technology is progressing, development and maintenance costs of UAVs are decreasing relatively. The focus is changing from use of one large UAV to use of multiple UAVs, which are integrated into teams that can coordinate to achieve high-level goals. This level of coordination requires new networking models that can be set up on highly mobile nodes such as UAVs in the fleet. Such networking models allow any two nodes to communicate directly if they are in the communication range, or indirectly through a number of relay nodes such as UAVs. Setting up an ad-hoc network between flying UAVs is a challenging issue, and requirements can differ from traditional networks, Mobile Ad-hoc Networks (MANETs) and Vehicular Ad-hoc Networks (VANETs) in terms of node mobility, connectivity, message routing, service quality, application areas, etc. This paper identifies the challenges with using UAVs as relay nodes in an ad-hoc manner, introduces network models of UAVs, and depicts open research issues with analyzing opportunities and future work.

Networking Models in Flying Ad-Hoc Networks (FANETs): Concepts and Challenges

Large homogeneous ad hoc wireless networks have a problem: the bandwidth available to a mobile user decreases as the number of nodes in the network increases. Using the embedded ad-hoc networking mechanism, nodes are able to transport packets across the network in a multihop fashion. An embedded mobile backbone is dynamically constructed to form a 2-level physical heterogeneous multihop wireless network. These backbone nodes provide two critical functions: (1) direct communication between neighboring cluster heads; and (2) efficient route discovery in HSR. With the broadcast feature of unmanned aerial vehicle (UAV), the link state can be broadcast to backbone nodes instead of "flooding" on the level 2. Thus, the routing overhead can be tremendously reduced, and the throughput will be improved. We modified hierarchical state routing (HSR) to have an intelligent selection algorithm to reduce the system latency caused by the long propagation delay of the UAV channel. The performance of the system is evaluated through simulation experiments.

https://www.cs.arizona.edu/~bzhang/paper/00-wcnc-uav.pdf

UAV aided intelligent routing for ad-hoc wireless network in single-area theater

Routing scalability in multi-hop wireless networks faces many challenges. The spatial concurrency constraint on nearby nodes sharing the same channel is the fundamental limitation. A previous theoretical study shows that the throughput furnished to each user is rapidly reduced as network size is increased. In order to solve this problem, we extended the hierarchical state routing scheme to a hierarchical multilayer environment. With the hierarchical approach, many problems caused by "flat" multi-hopping disappear. In the real battlefield, a multi-level physical heterogeneous network with UAVs provides an ideal support for the multi-area theater with a large number of fighting units. Extended hierarchical state relating (EHSR) shows very promising results in this hierarchical infrastructure.

Hierarchical routing for multi-layer ad-hoc wireless networks with UAVs

Multi-layer ad hoc wireless networks with UAVs is an ideal infrastructure to establish a rapidly deployable wireless communication system any time any where in the world for military applications. In this tactical environment, information traffic is quite asymmetric. Ground fighting units are information consumers and receive far more data than they transmit. The up-link is used for sending requests for information and some networking configuration overhead with a few kilobits, while the down-link is used to return the data requested with megabits size (e.g. multimedia file of images and charts). Centralized intelligent channel assigned multiple access (C-ICAMA) is a MAC layer protocol proposed for ground backbone nodes to access UAV (unmanned aerial vehicle) to solve the highly asymmetric data traffic in this tactical environment. With it's intelligent scheduling algorithm, it can dynamically allocate bandwidth for up-link and downlink to fit the instantaneous status of asymmetric traffic. The results of C-ICAMA is very promising, due to the dynamic bandwidth allocation of asymmetric up-link and down-link, the access delay is tremendously reduced.

C-ICAMA, a centralized intelligent channel assigned multiple access for multi-layer ad-hoc wireless networks with UAVs

In the future automated battle field communications will be supported in part by a hierarchical wireless network that includes: ad hoc ground radio subnets; point to point wireless long haul backbone, and; unmanned aerial vehicles (UAVs). In such a hierarchical network, nodes are generally partitioned into groups. Each group has one or more backbone nodes that provide access points to the backbone network and to UAVs. Communications between groups can thus utilize links at higher level. A critical protocol in the operation of such a large mobile network is routing. Previous research of UAV based systems has generally assumed the use of a hierarchical routing scheme, for example, extended hierarchical state routing (EHSR). However, a hierarchical scheme like EHSR has some limitations. In this paper, we extend landmark ad hoc routing (LANMAR) to a hierarchical structure with backbone nodes, high quality backbone links and UAVs. We show that the basic LANMAR scheme can be extended to incorporate backbone and UAV links. We will also show how backbone links and UAV links are automatically discovered by the LANMAR routing algorithm and are used effectively to reach remote destinations (thus reducing the hop distance). In other words, our scheme will combine the benefits of "flat" LANMAR routing and physical network hierarchy, without suffering of the intrinsic EHSR limitations.

http://ieeexplore.ieee.org/iel5/7739/21247/00985795.pdf

H. Ly

Papers

UAV aided intelligent routing for ad-hoc wireless network in single-area theater

Hierarchical routing for multi-layer ad-hoc wireless networks with UAVs

C-ICAMA, a centralized intelligent channel assigned multiple access for multi-layer ad-hoc wireless networks with UAVs

Landmark routing in large wireless battlefield networks using UAVs