Ns3 Projects

In this paper, a new network topology control mechanism is proposed to improve routing path duration in Aeronautical ad hoc network, which can effectively decrease the probability of routing path breaks in the process of nodes high-speed moving, and be integrated with existing routing protocols used in Adhoc network smoothly. The main principle of topology control mechanism is according to the different node densities with different topology construction method. For network regions having a high density of aircraft, the packets are preferentially routed over the long available links created by the aircraft moving in same direction.

For low density of aircraft, the routing preferentially uses the short available links created by the aircraft moving in both directions. This mechanism can increase the routing path duration effectively. We combine the topology control mechanism with OLSR, and give the Path Link Availability Routing Protocol (PLAR). We compare the performance of PLAR protocol with other routing protocols in different scenes. Experimental results show that, PLAR protocol exhibits a significant improvement over most routing protocols base on topology and position.

Mobile ad hoc network (Manet) is a kind of ad hoc network, Multihop with no fixed centralized node. Every node in Manet acts as host and router at the same time. Since nodes are highly dynamic, routing in such a network is challenging task. This article presents a routing strategy for Manet called Spatial Destination Sequenced Distance Vector (S-DSDV) which is an improved version of destination sequence distance vector (DSDV) routing protocol.

The proposed S-DSDV composed of 3 phases i.e. identification of activity area, identification of representative node and route discovery process. Finally S-DSDV reduces the overhead, end to end delay and increases network life time by sending and receiving more number of packet across the network and provides the better throughput when compare to DSDV routing protocol.

An increasing number of intelligent transportation applications require robust and reliable wireless adhoc communication. The process of communicating using radio requires a series of software and hardware modules to be functioning correctly. For many vehicle safety and automation applications communication is relied upon to the point where undetected faults can result in potentially dangerous situations, for example if a warning cannot be given in time to prevent a collision. The consequence of problems with any of the network components can be a partial or complete loss of radio communication.

Generally, most systems will consider network failure when there is no communication, but this overlooks problems where a partial fault causes degradation in the communication performance. There is a fundamental requirement to detect and respond to the partial failure of a network to ensure that communication is not intermittent, or performs poorly after a certain range. The partial loss of communication is difficult to detect, and is often overlooked in mobile ad hoc network applications. This paper introduces a novel method for modeling the antenna performance using collected data, and using the model to determine the probability that an antenna has some level of performance degradation.

With the shift towards wireless technology increasing at a faster rate than ever before, it is becoming ever more important to focus on optimising the routing functionality of a wireless network. The purpose of this paper is to outline the different types of routing that can be applied in a Mobile Ad Hoc Network(MANET) and to propose a new routing protocol named SOAP.

The SOAP routing protocol is designed as a cognitive hybrid protocol, making use of the functionality that exists in the popular proactive OLSR (Optimized Link State Routing) and reactive AODV (Ad hoc On-Demand Distance Vector) MANET routing protocols. The paper concludes that the SOAP protocol brings about performance improvements across a few Quality of Service metrics such as a lower delay than AODV and a lower routing overhead than OLSR but more work needs to be placed in ensuring its reliability and consistency across different network conditions. The SOAP protocol did not perform consistently in terms of packet loss and throughput and these issues should be addressed in further research.

We study the problem of disseminating videos to mobile users by using a hybrid cellular and ad hocnetwork. In particular, we formulate the problem of optimally choosing the mobile devices that will serve as gateways from the cellular to the ad hoc network, the ad hoc routes from the gateways to individual devices, and the layers to deliver on these ad hoc routes. We develop a Mixed Integer Linear Program (MILP)-based algorithm, called POPT, to solve this optimization problem. We then develop a Linear Program (LP)-based algorithm, called MTS, for lower time complexity.

While the MTS algorithm achieves close-to-optimum video quality and is more efficient than POPT in terms of time complexity, the MTS algorithm does not run in real time for hybrid networks with large numbers of nodes. We, therefore, propose a greedy algorithm, called THS, which runs in real time even for large hybridnetworks. We conduct extensive packet-level simulations to compare the performance of the three proposed algorithms. We found that the THS algorithm always terminates in real time, yet achieves a similar video quality to MTS. Therefore, we recommend the THS algorithm for video dissemination over hybrid cellular and ad hoc networks.

Lifetime optimization and security are two conflicting design issues for multi-hop wireless sensor networks (WSNs) with non-replenishable energy resources. In this paper, we first propose a novel secure and efficient Cost-Aware SEcure Routing (CASER) protocol to address these two conflicting issues through two adjustable parameters: energy balance control (EBC) and probabilistic-based random walking. We then discover that the energy consumption is severely disproportional to the uniform energy deployment for the given network topology, which greatly reduces the lifetime of the sensor networks. To solve this problem, we propose an efficient non-uniform energy deployment strategy to optimize the lifetime and message delivery ratio under the same energy resource and security requirement.

We also provide a quantitative security analysis on the proposed routing protocol. Our theoretical analysis and OPNET simulation results demonstrate that the proposed CASER protocol can provide an excellent tradeoff between routing efficiency and energy balance, and can significantly extend the lifetime of the sensor networks in all scenarios. For the non-uniform energy deployment, our analysis shows that we can increase the lifetime and the total number of messages that can be delivered by more than four times under the same assumption. We also demonstrate that the proposed CASER protocol can achieve a high message delivery ratio while preventing routing traceback attacks.

The Internet of Things (IoT) is becoming an attractive system paradigm to realize interconnections through the physical, cyber, and social spaces. During the interactions among the ubiquitous things, security issues become noteworthy, and it is significant to establish enhanced solutions for security protection. In this work, we focus on an existing U2IoT architecture (i.e., unit IoT and ubiquitous IoT), to design an aggregated-proof based hierarchical authentication scheme (APHA) for the layered networks.

Concretely, 1) the aggregated-proofs are established for multiple targets to achieve backward and forward anonymous data transmission; 2) the directed path descriptors, homomorphism functions, and Chebyshev chaotic maps are jointly applied for mutual authentication; 3) different access authorities are assigned to achieve hierarchical access control. Meanwhile, the BAN logic formal analysis is performed to prove that the proposed APHA has no obvious security defects, and it is potentially available for the U2IoT architecture and other IoT applications.

Cooperative wireless networking, which is promising in improving the system operation efficiency and reliability by acquiring more accurate and timely information, has attracted considerable attentions to support many services in practice. However, the problem of secure cooperative communication has not been well investigated yet. In this paper, we exploit physical layer security to provide secure cooperative communication for wireless ad hoc networks (WANETs) where involve multiple source-destination pairs and malicious eavesdroppers. By characterizing the security performance of thesystem by secrecy capacity, we study the secrecy capacity optimization problem in which security enhancement is achieved via cooperative relaying and cooperative jamming.

Specifically, we propose asystem model where a set of relay nodes can be exploited by multiple source-destination pairs to achieve physical layer security. We theoretically present a corresponding formulation for the relay assignment problem and develop an optimal algorithm to solve it in polynomial time. To further increase the system secrecy capacity, we exploit the cooperative jamming technique and propose a smart jamming algorithm to interfere the eavesdropping channels. Through extensive experiments, we validate that our proposed algorithms significantly increase the system secrecy capacity under various network settings.

A key design goal of erasure-coded storage clusters is to minimize reconstruction time, which in turn leads to high reliability by reducing vulnerability window size. PULL-Rep and PULL-Sur are two existing reconstruction schemes based on PULL-type transmission, where a rebuilding node initiates reconstruction by sending a set of read requests to surviving nodes to retrieve surviving blocks. To eliminate the transmission bottleneck of replacement nodes in PULL-Rep and mitigate the extra overhead caused by noncontiguous disk access in PULL-Sur, we incorporate PUSH-type transmissions to node reconstruction, where the reconstruction procedure is divided into multiple tasks accomplished by surviving nodes in a pipelining manner.

We also propose two PUSH-based reconstruction schemes (i.e., PUSH-Rep and PUSH-Sur), which can not only exploit the I/O parallelism of PULL-Sur, but also maintain sequential I/O accesses inherited from PULL-Rep. We build four reconstruction-time models to study the reconstruction process and estimate the reconstruction time of the four schemes in large-scale storage clusters. We implement a proof-of-concept prototype where the four reconstruction schemes are deployed and quantitatively evaluated. Experimental results show that the PUSH-based reconstruction schemes outperform the PULL-based counterparts. In a real-world (9,6)RS-coded storage cluster, PUSH-Rep speeds up the reconstruction time by a factor of 5.76 compared with PULL-Rep; PUSH-Sur accelerates the reconstruction by a factor of 1.85 relative to PULL-Sur.

With the recent advent of cloud computing technologies, a growing number of content distribution applications are contemplating a switch to cloud-based services, for better scalability and lower cost. Two key tasks are involved for such a move: to migrate the contents to cloud storage, and to distributethe web service load to cloud-based web services. The main issue is to best utilize the cloud as well as the application provider’s existing private cloud, to serve volatile requests with service response time guarantee at all times, while incurring the minimum operational cost. While it may not be too difficult to design a simple heuristic, proposing one with guaranteed cost optimality over a long run of the systemconstitutes an intimidating challenge.

Employing Lyapunov optimization techniques, we design a dynamic control algorithm to optimally place contents and dispatch requests in a hybrid cloud infrastructure spanning geo-distributed data centers, which minimizes overall operational cost over time, subject to service response time constraints. Rigorous analysis shows that the algorithm nicely bounds the response times within the preset QoS target, and guarantees that the overall cost is within a small constant gap from the optimum achieved by a T-slot lookahead mechanism with known future information. We verify the performance of our dynamic algorithm with prototype-based evaluation.