Scheduling in Successive Interference Cancellation based Wireless Ad Hoc Networks

Successive Interference Cancellation (SIC) allows multiple transmissions in the same neighborhood by enabling both concurrent reception and interference rejection via decoding and subtracting the signals successively from the composite received signal. In this paper, we study the scheduling problem for minimizing the schedule length required to satisfy the traffic demands of the links in SIC based wireless ad hoc networks.

Upon proving the NP-hardness of the problem, we propose a novel efficient heuristic scheduling algorithm based on the greedy assignment of the links to each time slot by using a novel metric called Interference Effect (IE). The IE of a feasible link is defined as the total Signal-to-Interference-plus-Noise Ratio (SINR) drop of the links in the scheduled set with the addition of that link. We demonstrate via extensive simulations that the proposed algorithm performs better than the previous algorithms, with lower computational complexity.

VaSili – A simulation runtime environment for applications in Vehicular Ad-Hoc Networks

In recent years, Vehicular Ad-Hoc Networks (VANETs) have become a very active research field. Since real-world experiments might involve potentially costly and complex hardware installations, simulations are a widely used alternative. However, due to, e.g., different scopes of functionality of available VANET simulators, simulations of VANET applications yield different results when using different simulators. Thus, it would be beneficial to test a VANET application in multiple simulation environments. Unfortunately, VANET applications are typically implemented inside of a certain simulator.

Hence, to switch the simulator, the source code of the application has to be adapted. To solve this problem, we developed a VANET API which defines the structure and interfaces of crucial VANET components to make them accessible in a unified way. We further developed VANET Simulation Runtime (VaSili), a framework which allows executing VANET API-compliant VANET applications in different VANET simulators without modification. Hence, applications developed using our proposed API can be run in different simulation environments and, since the VANET API is independent of VaSili, on real hardware.

A MAC protocol for link maintenance in multichannel cognitive radio ad hoc networks

To provide an efficient link maintenance approach, we propose a cross layer medium access control (LM-MAC) protocol for multichannel cognitive radio ad hoc networks. Link establishment and reliable transmission are two key problems for a perfect link maintenance mechanism. Since the cognitive user (CU) pairs have to reestablish their links each frame, in the proposed MAC protocol, three different access modes are designed to guarantee transmission efficiency in continuous frames. To enhance the transmission reliability, each CU will create a father spectrum list (FSL) after joining in the network.

FSL is divided into three groups of sub-channels with different functions to compensate the packet loss caused by the primary users’ appearance and the deep fading. Meanwhile, since the transmitter and the receiver will share the same FSL, periodical cooperative sensing is adopted to further optimize the former problem. Finally, compared with the existing opportunistic multichannel (OMC)-MAC protocol, the proposed LM-MAC protocol achieves better system performance in terms of saturation throughput, continuity and access delay.

New Reservation Multiaccess Protocols for Underwater Wireless Ad Hoc Sensor Networks

In a wireless network, where propagation delay is high and communications are sporadic, some kind of reservation protocol is generally used. Reservation access protocols were proposed earlier in earth stations-to-satellite communication with known propagation delay. However, optimality of the number of access slots with respect to the system performance parameters, such as system utilization, blocking probability, and delay, were not thoroughly studied. Besides, the effect of propagation delay uncertainty, which predominantly happens in underwater communications, are yet to be addressed. In this paper, we first analyze the system performance in many-to-one multiaccess data transfer scenario in underwater wireless ad hoc sensor networks with a fixed number of access slots and with the assumption of perfect propagation delay information.

We propose two system state aware dynamic approaches to suitably adjust the number of access slots, and investigate the optimum slotting strategy to maximize the system utilization. Next, by accounting the propagation delay uncertainty, we relook into the optimality criteria on the number of access slots, where we apply a modified receiver-synchronized slotted Aloha principle to maximize the access performance. Via mathematical analysis, supported by discrete event simulations, we show that the system utilization and blocking probability performances with our proposed dynamic reservation protocols are consistently better compared to the competitive reservation protocols with fixed as well as variable access slots. Further, we conduct NS3 simulations to study the protocol performances under more realistic channel and traffic conditions, which also demonstrate that the proposed optimized dynamic slotting offers a much better system utilization performance compared to a similar underwater reservation multiaccess protocol.

Application of fuzzy logic for selecting the route in AODV routing protocol for vehicular ad hoc networks

One of the known routing protocols in vehicular ad hoc networks is AODV routing protocol which usually uses the criterion of the minimum number of hops to select the route. According to frequent change of topology and the rapid movement of vehicles in these networks, considering the criterion of the minimum hops in AODV prevents selecting more stable routes and decreases the networkefficiency. The purpose of this paper is to increase the efficiency of AODV routing protocol using fuzzy logic.

Three criteria such as speed, direction and distance of vehicles to destination are used as the inputs of fuzzy system. The result of the fuzzy system can be considered as the probability of selecting route. The proposed protocol has been compared with AODV and FCAR. The evaluation results show that the proposed protocol has a lower average end to end delay than AODV. Packet delivery rate has also increased more than AODV and FCAR.

Weighted Sum Energy Efficiency Maximization in Ad Hoc Networks

In this letter, we propose a distributed adaptive-pricing algorithm aimed at solving the weighted sum energy efficiency (EE) maximization problem in ad hoc networks. It is theoretically proven that the proposed distributed algorithm strictly converges to the Karush-Kuhn-Tucker (KKT) point of the problem.

Significant performance enhancement is observed by numerical results with fast convergence. Moreover, it is shown that the proposed algorithm degrades gracefully when decreasing overhead of information exchange.

A Quasigroup based cipher algorithm for Ad-Hoc wireless networks

Security is the main concern in today’s wireless network environment. However, cipher algorithms consume a lot of resources to provide the required confidentiality. Ad-Hoc wireless networks are one area where the devices are extremely resource constrained. Therefore computationally simple yet cryptographically strong cipher algorithms are required for such kind of networks.

In this paper a light weight Quasi group based stream cipher is proposed and implemented on a Virtex-6 FPGA. It is also subjected to the NIST-STS test suite. Its performance is evaluated in MANETs using Glomosim simulator.

Dynamic Routing for Flying Ad Hoc Networks

This paper reports experimental results on self-organizing wireless networks carried by small flying robots. Flying ad hoc networks (FANETs) composed of small unmanned aerial vehicles (UAVs) are flexible, inexpensive and fast to deploy. This makes them a very attractive technology for many civilian and military applications. Due to the high mobility of the nodes, maintaining a communication link between the UAVs is a challenging task. The topology of these networks is more dynamic than that of typical mobile ad hoc networks (MANETs) and of typical vehicle ad hoc networks (VANETs). As a consequence, the existing routing protocols designed for MANETs partly fail in tracking network topology changes. In this work, we compare two different routing algorithms for ad hoc networks: optimized link-state routing (OLSR), and predictive-OLSR (P-OLSR).

The latter is an OLSR extension that we designed for FANETs; it takes advantage of the GPS information available on board. To the best of our knowledge, P-OLSR is currently the only FANET-specific routing technique that has an available Linux implementation. We present results obtained by both Media Access Control (MAC) layer emulations and real-world experiments. In the experiments, we used a test bed composed of two autonomous fixed-wing UAVs and a node on the ground. Our experiments evaluate the link performance and the communication range, as well as the routing performance. Our emulation and experimental results show that POLSR significantly outperforms OLSR in routing in the presence of frequent network topology changes.

Robustness analysis of mobile ad hoc networks using human mobility traces

With the rapid advancement of wireless technology and the exponential increase of wireless devices in the past decades, there are more consumer applications for MANETs (mobile ad hoc networks) in addition to the traditional military uses. A resilient and robust MANET is essential to high service quality for applications. The dynamically changing topologies of MANETs pose a huge challenge to normalnetwork operations. Furthermore, malicious attacks against critical nodes in the network could result in the deterioration of the network.

In this paper, we employ several real-world human mobility traces to analyze network robustness in the time domain. We apply attacks against important nodes of the human topology and compare the impact of attacks based on different centrality measures. Our results confirm that nodes with high betweenness in a well-connected large dynamic network play the most pivotal roles in the communication between all node pairs.

A new adaptive algorithm for data dissemination in Vehicular Ad hoc Networks

The idea or concept of intelligent traffic management in which data from the TIC (Traffic Information Centre) infrastructures could be reachable at any point is included mightily in Smart cities. Living labs (cities in which new designed systems can be tested in real conditions) have been created all over Europe to test the possibilities of these future cities. It’s the new concept where vehicular networks play relevant role. The Vehicular Ad-hoc Networks VANETs are a sub-class of the most studied Mobile Adhoc Networks MANET, in which vehicles are considered as mobile nodes. VANETs differ from other MANETs because of their specific characteristics, inducing numerous problems and constraints, which lead us to discuss many issues in VANETs as they are decentralized, self organized, self monitoring with distributed nature of network.

When and if deployed, VANETs will be the most implemented MANET ever and will continue their development over next years; it is indeed the reason why many issues are of great concern to be studied. Ample research efforts have been devoted to VANETs in the broadcasting domain. In order to have optimal and adaptive approaches, we focus on a number of requirements. In this light, this article will present an overview of VANETs, chiefly broadcasting protocols with the aim to resolve this relevant related issue, it also present some suggested broadcasting solutions and a propose a new algorithm with the idea of integrating the concept of Intelligent Traffic Lights ITLs in order to solve the core’s problem which is how to minimize the number of rebroadcast packets while maintaining good latency and reachability using dynamic parameters from the counter, probability based and distance based.