Top PDF Performance Evaluation of Packet Relaying in Ad Hoc Networks

Performance Evaluation of Packet Relaying in Ad Hoc Networks

Performance Evaluation of Packet Relaying in Ad Hoc Networks

It is important to mention that most of the studies of scaling laws of delay and throughput in wireless MANETs assume a uniform spatial distribution of nodes, which is the case, for example, when the nodes perform a symmetric Random Walk over the region of interest [6, 9], or when nodes move according to the Random Direction model [13]. In the present work, we replace this assump- tion by assuming that the inter-meeting time between two nodes, defined as the time duration time between two consecutive points in time where these nodes meet (i.e. come within transmission range of one another), is exponentially distributed. The validity of this assumption has been discussed in [8], and its accuracy has been shown for a number of mobility models (Random Walker, Random Direction, Random Waypoint) in the case when the node transmission range is small with respect to the area where the nodes evolve. It is worth pointing out that for some of these mobility models (non-symmetric Random Walk and Random Waypoint) nodes are not uniformly distributed over the area of interest.
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Authentication and consensus overhead in vehicular ad hoc networks

Authentication and consensus overhead in vehicular ad hoc networks

9 Conclusion and future work VANETs deployment has the potential to greatly increase vehicular safety and improve driving experience. But, ve- hicular communications need to be secured. Therefore, the DSRC standard for vehicular ad hoc networks is based on the ECDSA algorithm for supporting authentication mecha- nism. But, security mechanisms come with overheads that affect the performance of the V2V communications, and hence that of the safety applications. In this paper, we inves- tigate the total overhead of ECDSA, combining the packet size, processing and communication overheads. We focus on safety applications, and analyze the impact of the au- thentication on the braking distance. We conduct simulation study in order to evaluate the performance of secured beacon safety message dissemination in vehicular ad hoc networks. We pay special attention to safety requirements while study- ing networking performance issues.
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A Cross-layer Framework for Multiobjective Performance Evaluation of Wireless Ad Hoc Networks

A Cross-layer Framework for Multiobjective Performance Evaluation of Wireless Ad Hoc Networks

It is difficult to derive analytical models that provide bounds for more than two objectives at a time. As a conse- quence, providing a framework to obtain analytical bounds for multiple optimization objectives becomes relevant in the context of a practical two dimensional network. The modeling framework that we present facilitates the perfor- mance evaluation of multiple criteria. For the problem we address, we consider jointly optimizing reliable information transfer, end-to-end delay, and overall energy consumption. A similar approach in the context of routing design for wireless sensor networks has been proposed in [23] . In this paper, the network is fully connected and the authors look for the set of Pareto optimal routing unicast and multicast paths that minimize energy and delay. Hence, reliability is assumed to be guaranteed since all links are considered perfect and interference-free. This assumption is not made in our case and transmission between any two nodes is modeled using a fading channel. In this paper, the proba- bility of a successful transmission on a channel is derived according to the statistical distribution of interference. Our work therefore introduces a cross-layer approach that accurately accounts for the interference generated by the routing and resource allocation decisions.
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Cooperative Communications in Ad Hoc Networks

Cooperative Communications in Ad Hoc Networks

Issues in Cooperative Protocols The first challenge concerns the medium access method in distributed networks. Currently, the most popular Medium Access Control (MAC) protocol is the wifi one; it is conformed to the IEEE 802.11 standard. This protocol can support different transmission rates. The transmission rates are adjusted based on the channel conditions. If the distance between the terminals is important and/or the channel conditions are too bad, the message transmission is done at low rate. Thus, the performance of the whole distributed network (the packet delivery rations, for example) decreases. Moreover, if the channel conditions are really too bad, a network protocol should discover a multi-hop route that will pass through better links. However, multi-hop route may provide less rapid transmission links than the initial route (with the good channel quality). Therefore, the introduction of a relay terminal (or a helper terminal as named by different authors) would lead to high speed cooperative transmission and efficient route. Nevertheless, since a relay terminal and a source terminal have to access to the same medium, some additional exchanges have to be added to the IEEE 802.11 protocol in order to avoid collisions. Various protocols have been proposed in literature. In this content, we will focus on IEEE solutions, which will be presented in chapter 3, since our objective is to propose a MAC solution that is compatible with the IEEE 802.11.
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Simulation and Performance Analysis of MP-OLSR for Mobile Ad hoc Networks

Simulation and Performance Analysis of MP-OLSR for Mobile Ad hoc Networks

better end-to-end delay and load balancing. Because of the overlapping radio-coverage of neighbor nodes and that the limitation of the MAC protocol can result in strong interdependence between multi-routes, the multipath protocol performance gains achieved in ad hoc networks is not as much as in the wired Internet. Moreover, a pure source routing strategy, can appear as a sub-utilization of a good topology knowledge inherent in proactive behavior. We observe that the SR-MPOLSR has worse packet delivery ratio than the OLSR with link layer feedback. However, with the routing recovery, the MP-OLSR can achieve the best performance. To meet the requirement for a reliable transmission, the multiple routes are exploited by a multiple description coding based on Mojette Transform.
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Global visualization of experiments in ad hoc networks

Global visualization of experiments in ad hoc networks

To our knowledge, few works deal with such experiments. The works of [8, 9, 13] aim at depicting the behaviour of some particular routing (DSR for [8, 9] and ABR for [13]). Only APE [6] and Forwarding [2] are completely dedicated to experiments. Their goal is to ease the deployment of scenarios on real ad hoc network. APE concerns essentially the evaluation of routing protocols whereas the aim of Forwarding is to test the MAC protocols. As mentioned in [7], the studied metrics during experiments are essentially packet loss, jitter, end-to-end delay, throughput. All these metrics can be obtained with local log files collected during the experiment. No global visualization of the the run of the experiments is provided in the previously mentionned works. But it can be very useful to get a global log of the experiments. Such kinds of logs can give information on the schedule of the packets during the experiments, the possible spatial re-use, the possible collisions, etc. Such informations help in a better understanding of the protocols under evaluation.
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Authentication protocol runtime evaluation in distributed AAA framework for mobile ad-hoc networks

Authentication protocol runtime evaluation in distributed AAA framework for mobile ad-hoc networks

VI. C ONCLUSIONS AND F UTURE W ORKS In this paper, we analyzed the runtime resulting from the authentication of a joining node by a distributed AAA framework within a mobile ad-hoc network. The built model demonstrates that when routes are already established, the runtime increases as the number of servers rises and as the number of hops rises too. This value doesn’t exceed 380 milliseconds for a maximum of 6 servers and 10 hops. The undertaken simulations validated our model and hence showed that the investigated protocol is scalable when the routes are already established.
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Proximity aware routing in ad hoc networks

Proximity aware routing in ad hoc networks

Abstract: Most of the existing routing protocols for ad hoc networks are designed to scale in networks of a few hundred nodes. They rely on state concerning all links of the network or links on the route between a source and a destination. This may result in poor scaling properties in larger mobile networks or when node mobility is high. Using location information to guide the routing process is one of the most often proposed means to achieve scalability in large mobile networks. However, location- based routing is difficult when there are holes in the network topology. We propose a novel position- based routing protocol called Proximity Aware Routing for Ad-hoc networks (PARA) to address these issues. PARA selects the next hop of a packet based on 2-hops neighborhood information. We introduce the concept of “proximity discovery”. The knowledge of a node’s 2-hops neighborhood enables the protocol to anticipate concave nodes and helps reduce the risks that the routing protocol will reach a concave node in the network. Our simulation results show that PARA’s performance is better in sparse networks with little congestion. Moreover, PARA significantly outperforms GPSR for delivery ratio, transmission delay and path length. Our results also indicate that PARA delivers more packets than AODV under the same conditions.
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Performance Study of an Overlay Approach to Active Routing in Ad Hoc Networks

Performance Study of an Overlay Approach to Active Routing in Ad Hoc Networks

Network diameter ( d ref ) 1 1/2, 1/√2, 1, √2, 2 Overlay density (%) 12.5, 25, 37.5, 50, 62.5, 75, 87.5, 100 2) Static testbed goals: In our reactive approach of active routing, there is no neighbour probe before a route is needed. Active neighbours are implicitly detected during route discoveries. As long as the probability of finding a route composed uniquely of active nodes is high, it is sufficient to use all physical neighbours that are active as next hops. The Time To Live field of the ARREQ packet, the active range (AR), is set to one. This makes overlay neighbours process and eventually resend the ARREQs, while the passive neighbours simply drop them. However, if the network or overlay density is not high enough, a unitary active range may not be sufficient to allow communication. In the static study, we run each simulation with an increasing active range until it becomes successful and then log the performance obtained : path length, control traffic and delivery delay. We thus show RAR performance in the ideal case, i.e. when the active range used is the minimum one allowing to find a route between the source and destination nodes. The network characteristics, density and diameter, and the overlay density effect on performance are pointed out. We take the AODV protocol as a reference for evaluating RAR.
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Congestion Control in Vehicular Ad Hoc Networks

Congestion Control in Vehicular Ad Hoc Networks

Mobile Computing and Networking Research Laboratory (LARIM), Department of Computer Engineering, Polytechnique de Montréal, Montreal, Canada Abstract Vehicular Ad Hoc Networks (VANets) is considered as a technology which can increase safety and convenience of drivers and passenger. Due to channel congestion in high density situation, VANets’ safety applications suffer of performance degradation. In order to improve performance, reliability, and safety over VANets, congestion control should be taken into account. However, congestion control is a challenging task due to the special characteristics of VANets (e.g. high mobility, high rate of topology change, frequently route break, and so on). In this paper, DySch and TaSch strategies are proposed. Those strategies assign priorities to the safety and service messages based on the content of messages (static factor), state of network (dynamic factor) and size of messages. DySch and TaSch strategies schedule the messages dynamically and heuristically, respectively. Their performance is investigated using highway and urban scenarios while the average delay, average throughput, number of packet loss, packet loss ratio, and waiting delay in queues are considered. Simulation results show that DySch and TaSch strategies can significantly improve the performance of VANets in comparison to the best conventional strategies. Employing the proposed strategies to control congestion in VANets helps increase reliability and safety by giving higher priority to the safety messages.
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Authentication services in mobile ad hoc networks

Authentication services in mobile ad hoc networks

Before using virtualization it is important also to know the possible vulnerabilities of the package to use in order to implement basic security mechanism that can ensure the isolation and protection of the host environment and guest machines. In the case of securing the routing protocol we worked with an active routing protocol called OLSR. We used an open source daemon implementation (www.olsr.org). This daemon already has a secure plugin which uses a shared key to sign the packets and uses timestamps to avoid replay attacks and establish neighbor trust relationships. Regarding the key, it assumes that it is already available for the nodes that join the network. In our solution we modified the secure plugin of OLSR daemon to add an authentication phase and we called it Authenticated OLSR (AOLSR), thus we assume also the availability of a shared key while the authentication process could protect the network from attacker that were able to get the shared key. It means, there is an initial node that acts as Authentication server and runs AOLSR which will enable the formation of a MANET, then any node that wants to join the network has to run AOLSR and has to be authenticated by the server, if succeeds it will be part of the network. For practical implementation we add new functions in the secure plugin to have authentication, in fact we keep the timestamp procedure and we added access control conditions for authentication and a new table to keep the known and authenticated IP address of the neighbors. We tested the implementation among three nodes and it worked, however a deep evaluation is required to test the performance of this solution.
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Routing and Broadcasting in Hybrid Ad Hoc Networks

Routing and Broadcasting in Hybrid Ad Hoc Networks

Projet POPS Rapport technique n° 0291 — Février 2004 — 14 pages Abstract: Hybrid ad hoc networks consist of two kinds of nodes, regular nodes and nodes with additional capabilities. For example, multi-hop cellular and wireless Internet networks consist of static or mobile nodes and access points to a fixed infrastructure. Each node may access fixed infrastructure either directly or via other nodes in multi-hop fashion. Another example is heterogeneous sensor networks, which consists of regular tiny sensors, and spe- cial nodes capable of communicating between themselves and to monitoring station using their own backbone network. In this paper, we propose some protocols for broadcasting and routing in hybrid ad hoc networks. Hybrid blind flooding uses backbone of access nodes to spread the message, otherwise blind flooding is applied. Component neighbor elimination based flooding applies neighbor elimination based broadcasting separately within each com- ponent, consisting of all nodes with the same closest access point. In adaptive flooding, each node additionally estimates whether each of its neighbor from a different component already received the packet via its own access point in the neighbor elimination process. Multipoint relaying, and dominating set based broadcasting are generalized from existing ad hoc net- work protocols, utilizing the capabilities of access points. These broadcasting protocols can be applied for route discovery in proactive or reactive routing protocols for hybrid ad hoc networks. Hybrid routing protocol for hybrid ad hoc networks applies proactive routing to maintain the link to the closest access point, and reactive routing to find route between two ad hoc nodes. Access points cooperate to reduce the hop count of later route discovery.
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Performance evaluation of reactive and proactive routing protocol in IEEE 802.11 ad hoc network

Performance evaluation of reactive and proactive routing protocol in IEEE 802.11 ad hoc network

2.1.2. AODV A source node that wants to send a message to a destination for which it does not have a route, broadcasts a request RREQ packet. All nodes receiving this packet update their information for the source node and maintain only the next hop’s address in a routing table. A RREQ packet contains the source node’s address, broadcast ID, current sequence number and the most recent sequence number of the destination node. The response packet RREP is sent by either the destination or a node that has a route to the destination with the sequence number greater than or equal to the sequence number in the RREQ packet. The route is established once the source node receives the RREP. AODV algorithm includes route maintenance facilities. When a link is broken, the related node sends a RERR message to the neighboring nodes using that route. The main advantage of AODV compared to DSR is the reduced bandwidth due to smaller control and data packet. This algorithm has also good scalability because it needs only two addresses: destination and next hop. However, it works with symmetric links and does not allow for multipath routing. So, new routes must be discovered when a link breaks down. 6
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Performance Evaluation of Broadcasting Protocols for Ad Hoc and Sensor Networks

Performance Evaluation of Broadcasting Protocols for Ad Hoc and Sensor Networks

v if v is not the smallest id neighbor of u. The rule 1 becomes: if it has the smallest id in its neighborhood and it has at least 2 unconnected neighbors. In [2], Basagni et al. proposed a performance comparison of various protocols for computing backbones in ad hoc networks, including the previously cited protocols. They measured miscellaneous parameters, like the computation com- plexity (needed time to create the backbone), the backbone size or even the energy consumption per node in order to determine which protocol suits the best to ad hoc networks. They concluded that Wu and Li’s algorithm used in conjunc- tion with the variant by Stojmenovi´ c et al. [8] is an excellent compromise with respect to all the considered metrics, and overall far superior than any other approach that exists in literature. We therefore limited our study to listed protocols, refering to [2] for justification for not including other approaches in the study. The primary reason for superior perfor- mances of selected protocols is their localized nature, with low overhead for gaining needed neighbor knowledge, and low message overhead involved in constructing and maintaining the underlying backbones.
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Efficient packet transmission in wireless ad hoc networks with partially informed nodes

Efficient packet transmission in wireless ad hoc networks with partially informed nodes

assumed to lie in discrete sets (of states): H i = H  i = H = {h min , . . . , h max } with | H i | = | H  i | = | H| = H; the real- izations of each channel gain will be assumed to be i.i.d.. Technically, continuous channel gains might be assumed. But, as done in the information theory literature for estab- lishing coding theorems, we address the discrete case in the first place, since the continuous case can be obtained by classical arguments (such as assuming standard proba- bility spaces), whereas the converse is not true. Now, from the practical aspect, quantizing the channel gains typi- cally induces a small performance loss compared to the continuous case; one figure assuming a typical scenario illustrates this. The corresponding channel gain model naturally applies to time-selective frequency flat fading single-input single-output channels. If the channel gain is interpreted as the combined effect of path loss and shad- owing, our model can also be used to study more general channel models such as multiple-input multiple-output channels. Fourth, the utility function of a node has a more general form than in the forwarder’s dilemma. The instan-
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A Cross-layer Framework for Multiobjective Performance Evaluation of Wireless Ad Hoc Networks

A Cross-layer Framework for Multiobjective Performance Evaluation of Wireless Ad Hoc Networks

Understanding the trade-offs involved with various routing solutions will enable adaptive resource manage- ment across layers and nodes, leading to a more accurate ‘‘local to global performance mapping’’ for practical rout- ing protocol design. The identification of Pareto optimal solutions provides not only achievable performance bounds, but also specific solution sets for the routing and resource allocation algorithms to operate at those bounds. In this paper, we propose a novel framework capable of providing a bound for joint optimization of multiple per- formance metrics. Our proposed framework comprises both a probabilistic cross-layer network model and a mul- tiobjective optimization problem formulation. Our pro- posed cross-layer network model captures more accurately the interactions between routing decisions and resource allocation, assuming a basic random medium ac- cess control protocol. With its intrinsic probabilistic defini- tion, it is capable of defining various routing techniques such as multi-hop single path routes, broadcast protocols or multi-path protocols. The multiobjective optimization problem is solved using the Parallel Multiobjective Tabu Search (PMOTS) algorithm to retrieve the set of Pareto optimal solutions. This global cross-layer multiobjective framework is applied herein to tackle the problem of ro- bust routing and resource allocation for wireless sensor networks. The following three criteria are relevant in this context: (i) reliability defined as the probability of having a successful packet transmission, (ii) delay, defined as the average end-to-end delay in the network, and (iii) the for- warding energy, defined as the energy spent by the net- work for relaying.
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Authentication and consensus overhead in vehicular ad hoc networks

Authentication and consensus overhead in vehicular ad hoc networks

9 Conclusion and future work VANETs deployment has the potential to greatly increase vehicular safety and improve driving experience. But, ve- hicular communications need to be secured. Therefore, the DSRC standard for vehicular ad hoc networks is based on the ECDSA algorithm for supporting authentication mecha- nism. But, security mechanisms come with overheads that affect the performance of the V2V communications, and hence that of the safety applications. In this paper, we inves- tigate the total overhead of ECDSA, combining the packet size, processing and communication overheads. We focus on safety applications, and analyze the impact of the au- thentication on the braking distance. We conduct simulation study in order to evaluate the performance of secured beacon safety message dissemination in vehicular ad hoc networks. We pay special attention to safety requirements while study- ing networking performance issues.
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CONNECTION TIMES IN LARGE AD-HOC MOBILE NETWORKS

CONNECTION TIMES IN LARGE AD-HOC MOBILE NETWORKS

T . This is one of the most decisive quantities in such a system, since it measures the quality of the entire system by means of two sample participants. The regime in which we will be working is the limit of a large number of participants, coupled with the limit of a large region such that the population density (number of participants per area unit) is of finite positive order. In the language of statistical mechanics, this is the thermodynamic limit. We will condition on the two sample trajectories. The connection time is obviously a complex function of the entire system, but we will be able to quantify the influence of the large number of the participants on the connectivity of the two sample participants in terms of a simple function. This function is known from the theory of continuum percolation, which studies connectivity through a union of randomly distributed balls. It turns out that the limiting connection time has a global, deterministic part and a local, probabilistic part, the latter of which is described in terms of the mentioned function. Furthermore, it also turns out that this limit is deterministic, given the two sample participants. This is due to one of our assumptions on the movement scheme, which requires that knowledge about the walker’s location at a later time point does not fix the current location with positive probability. This assumption implies a certain independence of the locations of the totality of the walkers at any two given times and leads to a deterministic limit. This is presented in Sections 1.2 and 1.3.
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Service Provision in Disconnected Mobile Ad Hoc Networks

Service Provision in Disconnected Mobile Ad Hoc Networks

the network, and the header lifetime specifies that this mes- sage should be considered as being valid for only twelve hours after this date. The header md5sum-content, which is the md5 sum of the content, is expected to help node in the content-based management. In both service response and service advertisement, the md5 sum of the request as- sociated with the response or with the advertisement is also specified. With such an information a mobile host receiving a service invocation request pertaining to a service that it not provides itself, but for which it has already played the role of forwarder, can reply itself to this message by sending the response that it has stored previously in its local cache, whether this one is still valid obviously. The headers can also include contextual properties such as the GPS position of the sender.
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Ad Hoc Mobility Notification in Wireless Infrastructure Networks

Ad Hoc Mobility Notification in Wireless Infrastructure Networks

Research efforts aiming at merging cellular wireless and ad hoc networking have been recently increasing [ 5 , 26 , 6 , 13 , 2 , 23 , 7 ]. Hybrid networks, the extension of cellular network using ad hoc connectivity, offer obvious benefits. On one hand, they allow an extension cellular networks range using ad hoc connectivity and on the other hand they provide a global Internet connectivity to ad hoc nodes. However, deployment of a wired cellular infrastructure still represents a high cost as well as a lot of constraints. Both costs and constraints can be reduced if we replace the wired infrastructure network by a fully wireless one. The infrastructure network becomes a collection of static wireless nodes acting both as base stations and infrastructure routers. Infrastructure communications become wireless multi- hop communications. As the wireless medium really differs from the wired one (pervasive medium, non isolated links, higher latency and lower bandwidth), the design of classical micro-mobility protocols must be rethought and if necessary altered. As it seems hard to achieve as good performances in a wireless hybrid network as in a wired one, a deeper attention must be given to each layer of the networking stack in order to design protocols in adequation with the wireless medium characteristics.
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