A Statistical Analysis of the Long-Run Node Spatial Distribution in Mobile Ad

In this paper, we analyze the node spatial distribution of mobile wireless ad hoc networks. Characterizing this distribution is of fundamental importance in the analysis of many relevant properties of mobile ad hoc networks, such as connectivity, average route length, and network capacity. In particular, we have investigated under what conditions the node spatial distribution resulting after a large number of mobility steps resembles the uniform distribution. This is motivated by the fact that the existing theoretical results concerning mobile ad hoc networks are based on this as sumption. In order to test this hypothesis, we performed extensive simulations using two well-known mobility models: the random waypoint model, which resembles intentional movement, and a Brownian-like model, which resembles non-intentional movement. Our analysis has shown that in the Brownian-like motion the uniformity assumption does hold,and that the intensity of the concentration of nodes in the center of the deployment region that occurs in the ran dom waypoint model heavily depends on the choice of some mobility parameters. For extreme values of these parameters,the uniformity assumption is impaired

The critical transmitting range for Connectivity in Mobile Packet Radio Networks

It is known that the critical transmitting range for connectivity in stationary packet radio networks is $r=c sqrt{frac{log n}{n}}$, for some constant $c!>!0$, under the assumption that $n$ nodes are uniformly distributed in $R=[0,1]^2$. In this note, we investigate how mobility affects this asymptotic result. We consider the well known random waypoint mobility model, whose asymptotic node spatial distribution has been recently derived. We prove that as long as the spatial distribution has a non-null uniform component, the mobile critical transmitting range differs from the stationary one at most by a constant factor. On the contrary, when the uniform component is null there is an asymptotic gap between the mobile and stationary case, i.e. $r!gg!c sqrt{frac{log n}{n}}$ for any constant $c!>!0$. Hence, the asymptotic behavior of the mobile critical transmitting range depends on the choice of the mobility parameters

Improving Network Performance with Affinity based Mobility Model in Opportunistic Network

Opportunistic network is a type of Delay Tolerant Network which is characterized by intermittent connectivity amongst the nodes and communication largely depends upon the mobility of the participating nodes. The network being highly dynamic, traditional MANET protocols cannot be applied and the nodes must adhere to store-carry-forward mechanism. Nodes do not have the information about the network topology, number of participating nodes and the location of the destination node. Hence, message transfer reliability largely depends upon the mobility pattern of the nodes. In this paper we have tried to find the impact of RWP (Random Waypoint) mobility on packet delivery ratio. We estimate mobility factors like number of node encounters, contact duration(link time) and inter-contact time which in turn depends upon parameters like playfield area (total network area), number of nodes, node velocity, bit-rate and RF range of the nodes. We also propose a restricted form of RWP mobility model, called the affinity based mobility model. The network scenario consists of a source and a destination node that are located at two extreme corners of the square playfield (to keep a maximum distance between them) and exchange data packets with the aid of mobile 'helper' nodes. The source node and the destination node are static. The mobile nodes only help in relaying the message. We prove how affinity based mobility model helps in augmenting the network reliability thereby increasing the message delivery ratio and reduce message delivery latency.Comment: IJWMN Journal, Opportunistic Network, 14 pages, 10 figures with Appendi

Formal and Executable Specification of Random Waypoint Mobility Model Using Timed Coloured Petri Nets for WMN

The wireless mesh network (WMN) is an emerging and cost-effective alternative paradigm for the next generation wireless networks in many diverse applications. In the performance evaluation of routing protocol for the WMN, it is essential that it should be evaluated under realistic conditions. The usefulness of specific mobility protocol can be determined by selection of mobility model. This paper introduces a coloured Petri nets (CP-nets) based formal model for implementation, simulation, and analysis of most widely used random waypoint (RWP) mobility model for WMNs. The formal semantics of hierarchical timed CP-nets allow us to investigate the terminating behavior of the transitions using state space analysis techniques. The proposed implementation improves the RWP mobility model by removing the “border effect” and resolves the “speed decay” problem

Maximizing Transmission Opportunities in Wireless Multihop Networks

Being readily available in most of 802.11 radios, multirate capability appears to be useful as WiFi networks are getting more prevalent and crowded. More specifically, it would be helpful in high-density scenarios because internode distance is short enough to employ high data rates. However, communication at high data rates mandates a large number of hops for a given node pair in a multihop network and thus, can easily be depreciated as per-hop overhead at several layers of network protocol is aggregated over the increased number of hops. This paper presents a novel multihop, multirate adaptation mechanism, called multihop transmission opportunity (MTOP), that allows a frame to be forwarded a number of hops consecutively to minimize the MAC-layer overhead between hops. This seemingly collision-prone nonstop forwarding is proved to be safe via analysis and USRP/GNU Radio-based experiment in this paper. The idea of MTOP is in clear contrast to the conventional opportunistic transmission mechanism, known as TXOP, where a node transmits multiple frames back-to-back when it gets an opportunity in a single-hop WLAN. We conducted an extensive simulation study via OPNET, demonstrating the performance advantage of MTOP under a wide range of network scenarios

A Realistic Mobility Model for Wireless Networks of Scale-Free Node Connectivity

Recent studies discovered that many of social, natural and biological networks are characterised by scale-free power-law connectivity distribution. We envision that wireless networks are directly deployed over such real-world networks to facilitate communication among participating entities. This paper proposes Clustered Mobility Model (CMM), in which nodes do not move randomly but are attracted more to more populated areas. Unlike most of prior mobility models, CMM is shown to exhibit scale-free connectivity distribution. Extensive simulation study has been conducted to highlight the difference between Random WayPoint (RWP) and CMM by measuring network capacities at the physical, link and network layers

The Node Spatial Distribution of the Generalized Random Waypoint Mobility Model for Wireless Ad Hoc Networks

In this paper we analyze the node spatial distribution generated by nodes moving according to the random waypoint model, which is widely used in the simulation of mobile ad hoc networks. We extend an existing analysis for the case in which nodes are continuously moving (i.e., the pause time is 0) to the more general case in which nodes have arbitrary pause times between movements. We also generalize the mobility model, allowing the nodes to remain stationary for the entire simulation time with a given probability. Our analysis shows that the structure of the resulting asymptotic spatial density is composed by three distinct components: the initial, the pause and the mobility component. The relative values of these components depend on the mobility parameters. We derive an explicit formula of the one-dimensional node spatial density, and an approximated formula for the two-dimensional case. The quality of this approximation is verified through experimentation, which shows that the accuracy heavily depends on the choice of the mobility parameters

A survey on mobility models for performance analysis in tactical mobile networks, Journal of Telecommunications and Information Technology, 2008, nr 2

In scenarios of military operations and catastrophes – even when there is no infrastructure available or left – there is a need for communication. Due to the specific context the communication systems used in these tactical scenarios need to be as reliable as possible. Thus, the performance of these systems has to be evaluated. Beside field-tests, computer simulations are an interesting alternative concerning costs, scalability, etc. Results of simulative performance evaluation strongly depend on the models used. Since tactical networks consist of, or, at least, contain mobile devices, the mobility model used has a decisive impact. However, in common performance evaluations mainly simple random-based models are used. In the paper we will provide classification and survey of existing mobility models. Furthermore, we will review these models concerning the requirements for tactical scenarios

Connectivity, Coverage and Placement in Wireless Sensor Networks

Wireless communication between sensors allows the formation of flexible sensor networks, which can be deployed rapidly over wide or inaccessible areas. However, the need to gather data from all sensors in the network imposes constraints on the distances between sensors. This survey describes the state of the art in techniques for determining the minimum density and optimal locations of relay nodes and ordinary sensors to ensure connectivity, subject to various degrees of uncertainty in the locations of the nodes