D.L. Gu

Bio: D.L. Gu is an academic researcher from University of California, Los Angeles. The author has contributed to research in topics: Wireless network & Hierarchical routing. The author has an hindex of 4, co-authored 4 publications receiving 346 citations.

Adaptive Security for Multi-layer Ad-hoc Networks

Abstract: Secure communication is critical in military environments where the network infrastructure is vulnerable to various attacks and compromises A conventional centralized solution breaks down when the security servers are destroyed by the enemies In this paper we design and evaluate a security framework for multi-layer ad-hoc wireless networks with unmanned aerial vehicles (UAVs) In battlefields, the framework adapts to the contingent damages on the network infrastructure Depending on the availability of the network infrastructure, our design is composed of two modes In infrastructure mode, security services, specifically the authentication services, are implemented on UAVs that feature low overhead and flexible managements When the UAVs fail or are destroyed, our system seamlessly switches to infrastructureless mode, a backup mechanism that maintains comparable security services among the surviving units In the infrastructureless mode, the security services are localized to each node’s vicinity to comply with the ad-hoc communication mechanism in the scenario We study the instantiation of these two modes and the transitions between them Our implementation and simulation measurements confirm the effectiveness of our design

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

Abstract: 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.

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

Abstract: 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.

Landmark routing in large wireless battlefield networks using UAVs

Abstract: 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.

Secure routing in wireless sensor networks: attacks and countermeasures

Abstract: We consider routing security in wireless sensor networks. Many sensor network routing protocols have been proposed, but none of them have been designed with security as a goal. We propose security goals for routing in sensor networks, show how attacks against ad-hoc and peer-to-peer networks can be adapted into powerful attacks against sensor networks, introduce two classes of novel attacks against sensor networks sinkholes and HELLO floods, and analyze the security of all the major sensor network routing protocols. We describe crippling attacks against all of them and suggest countermeasures and design considerations. This is the first such analysis of secure routing in sensor networks.

Statistical en-route filtering of injected false data in sensor networks

Abstract: In a large-scale sensor network individual sensors are subject to security compromises. A compromised node can be used to inject bogus sensing reports. If undetected, these bogus reports would be forwarded to the data collection point (i.e., the sink). Such attacks by compromised nodes can result in not only false alarms but also the depletion of the finite amount of energy in a battery powered network. In this paper, we present a statistical en-route filtering (SEF) mechanism to detect and drop false reports during the forwarding process. Assuming that the same event can be detected by multiple sensors, in SEF each of the detecting sensors generates a keyed message authentication code (MAC) and multiple MACs are attached to the event report. As the report is forwarded, each node along the way verifies the correctness of the MAC's probabilistically and drops those with invalid MACs. SEF exploits the network scale to filter out false reports through collective decision-making by multiple detecting nodes and collective false detection by multiple forwarding nodes. We have evaluated SEF's feasibility and performance through analysis, simulation, and implementation. Our results show that SEF can be implemented efficiently in sensor nodes as small as Mica2. It can drop up to 70% of bogus reports injected by a compromised node within five hops, and reduce energy consumption by 65% or more in many cases.

Intrusion detection in wireless ad hoc networks

Abstract: Intrusion detection has, over the last few years, assumed paramount importance within the broad realm of network security, more so in the case of wireless ad hoc networks. These are networks that do not have an underlying infrastructure; the network topology is constantly changing. The inherently vulnerable characteristics of wireless ad hoc networks make them susceptible to attacks, and it may be too late before any counter action can take effect. Second, with so much advancement in hacking, if attackers try hard enough they will eventually succeed in infiltrating the system. This makes it important to constantly (or at least periodically) monitor what is taking place on a system and look for suspicious behavior. Intrusion detection systems (IDSs) do just that: monitor audit data, look for intrusions to the system, and initiate a proper response (e.g., email the systems administrator, start an automatic retaliation). As such, there is a need to complement traditional security mechanisms with efficient intrusion detection and response. In this article we present a survey on the work that has been done in the area of intrusion detection in mobile ad hoc networks.

Channel surfing and spatial retreats: defenses against wireless denial of service

Abstract: Wireless networks are built upon a shared medium that makes it easy for adversaries to launch denial of service (DoS) attacks. One form of denial of service is targeted at preventing sources from communicating. These attacks can be easily accomplished by an adversary by either bypassing MAC-layer protocols, or emitting a radio signal targeted at jamming a particular channel. In this paper we present two strategies that may be employed by wireless devices to evade a MAC/PHY-layer jamming-style wireless denial of service attack. The first strategy, channel surfing, is a form of spectral evasion that involves legitimate wireless devices changing the channel that they are operating on. The second strategy, spatial retreats, is a form of spatial evasion whereby legitimate mobile devices move away from the locality of the DoS emitter. We study both of these strategies for three broad wireless communication scenarios: two-party radio communication, an infrastructured wireless network, and an ad hoc wireless network. We evaluate several of our proposed strategies and protocols through ns-2 simulations and experiments on the Berkeley mote platform.

Wireless Relay Communications with Unmanned Aerial Vehicles: Performance and Optimization

Abstract: 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.