385 research outputs found
Design and Analysis of SD_DWCA - A Mobility based clustering of Homogeneous MANETs
This paper deals with the design and analysis of the distributed weighted
clustering algorithm SD_DWCA proposed for homogeneous mobile ad hoc networks.
It is a connectivity, mobility and energy based clustering algorithm which is
suitable for scalable ad hoc networks. The algorithm uses a new graph parameter
called strong degree defined based on the quality of neighbours of a node. The
parameters are so chosen to ensure high connectivity, cluster stability and
energy efficient communication among nodes of high dynamic nature. This paper
also includes the experimental results of the algorithm implemented using the
network simulator NS2. The experimental results show that the algorithm is
suitable for high speed networks and generate stable clusters with less
maintenance overhead
Design and Performance Analysis of an Aeronautical Routing Protocol with Ground Station Updates
Aeronautical routing protocol (AeroRP) is a position-based routing protocol developed for highly dynamic airborne networks. It works in conjunction with the aeronautical network protocol (AeroNP). AeroRP is a multi-modal protocol that operates in different modes depending on the mission requirements. Ground station (GS) update mode is an AeroRP mode in which the GS sends geolocation or topology updates to improve routing accuracy. The main contribution of this thesis is to develop and implement the GS updates in AeroRP and analyse its performance in the various modes and compare them against canonical MANET routing protocols such as DSDV, OLSR, AODV, and DSR. The simulation analysis shows that AeroRP outperforms the traditional MANET protocols in various scenarios
A framework and mathematical modeling for the vehicular delay tolerant network routing
Vehicular ad hoc networks (VANETs) are getting growing interest as they are expected to play crucial role in making safer, smarter, and more efficient transportation networks. Due to unique characteristics such as sparse topology and intermittent connectivity, Delay Tolerant Network (DTN) routing in VANET becomes an inherent choice and is challenging. However, most of the existing DTN protocols do not accurately discover potential neighbors and, hence, appropriate intermediate nodes for packet transmission. Moreover, these protocols cause unnecessary overhead due to excessive beacon messages. To cope with these challenges, this paper presents a novel framework and an Adaptive Geographical DTN Routing (AGDR) for vehicular DTNs. AGDR exploits node position, current direction, speed, and the predicted direction to carefully select an appropriate intermediate node. Direction indicator light is employed to accurately predict the vehicle future direction so that the forwarding node can relay packets to the desired destination. Simulation experiments confirm the performance supremacy of AGDR compared to contemporary schemes in terms of packet delivery ratio, overhead, and end-to-end delay. Simulation results demonstrate that AGDR improves the packet delivery ratio (5-7%), reduces the overhead (1-5%), and decreases the delay (up to 0.02 ms). Therefore, AGDR improves route stability by reducing the frequency of route failures. © 2016 Mostofa Kamal Nasir et al
Polycyclic aromatic hydrocarbons biodegradation using isolated strains under indigenous condition
The treatment and disposal of domestic sIudge is an expensive and environmentally sensitive
problem. It is also a growing problem since sludge production will continue to increase as
new wastewzter treatment plants are built due to population increase. The large volume of
domestic sIudge produced had made it difficult for many countries including Malaysia to
assure complete treatment of the sludge before discharging to the receiving environment.
Domestic sludge contains diverse range of pollutants such as pathogen, inorganic and organic
compounds. These pollutants are toxic, mutagenic or carcinogenic and may threaten human
health. Iiilproper disposal and handling of sludge may pose serious impact to the environment
especially on soil and water cycles. Previous studies on Malaysian domestic sludge only
reported on bulk parameters and heavy metals. Thus, no study reported on organic micro
pollutants, namely, polycylic aromatic hydrocarbons (PAHs). Their recalcitrance and
persistence make them problematic environmental contaminants. Microbial degradation is
considered to be the primary mechanism of PAHs removal from the environment. Much has
been reported on biodegradation of PAHs in several countries but there is a lack of
information quantitative on this subject in Malaysia. This study is carried out to understand
the nature of domestic sludge and to provide a better understanding on the biodegradation
processes of PAHs. The methodology of this study comprised field activities, laboratory work
and mathematical modelling. Field activities involved sampling of domestic sludge from
Kolej Mawar, Universiti Teknologi MARA, Shah Alam, Selangor. Laboratory activities
include seven phases of experimental works. First phase is characterization study of domestic
sludge based on bulk parameters, heavy metals and PAHs. Second phase is enrichment and
purification of bacteria isolated from domestic sludge using single PAHs and mixed PAHs as
growth substrate. This was followed by identification of bacteria using BIOLOG system. The
fourth phase focussed on turbidity test to monitor growth rate of the isolated bacteria.
Preliminary degradation study involves optimization of the process at different substrate
concentration, bacteria concentration, pH and temperature. The optimum conditions
established from optimization study were used in degradation study. In biodegradation study,
two experimental conditions were performed. These conditions include using bacteria isolated
from single PAHs as substrate and bacteria isolated from mixed PAHs. Protein and pH tests
were done during degradation study. Final activity is mathematical modelling of the
biodegradation process. In general results on bulk parameters are comparable to previous
studies. Zinc was the main compound with a mean concentration of 11 96.4 mglkg. PAHs
were also detected in all of the samples, with total concentration between 0.72 to 5.36 mglkg
dry weight for six PAHs. In the examined samples, phenanthrene was the main compound
with a mean concentration of 1.0567 mglkg. The results fiom purification studies of bacteria
strains sucessfull isolated 13 bacteria strains fiom single PAH substrate while three bacteria
were isolated from the mixed PAHs substrate. Based on bacteria growth rates, only six strains
grown on single PAHs and three strains grown on mixed PAHs were used for further studies.
Results from the optimization study of biodegradation indicated that maximum rate of PAHs
removal occurred at 100 mg~-' of PAHs, 10% bacteria concentration, pH 7.0 and 30°C. The
results showed that bacteria grown on lower ring of PAHs are not able to grow on higher ring
of PAHs. As for example Micrococcus diversus grown on napthalene as sole carbon source
was unable to degrade other PAHs like acenapthylene, acenapthene, fluorene, phenanthrene
and antlracene. In the case of bacteria isolated from mixed PAHs, the results showed that
most of the napthalene was degraded by isolated strains with the highest average degradation
rate followed by acenapthylene, acenapthene, fluorene, phenanthrene and anthracene. 377.1�781.8�781�+
D4ff + c\,cpda~ition trends were observed in the study could be attributed to the different
subsr , i,lo\~ir 'Led during isolation process. Interaction through cometabolism and synergistic
ocolq bacteria strains isolated from single substrate. Thus, only synergistic interaction
was oL, :a 77ed for bacteria isolated from mixed substrate. Corynebacterium urolyticum
re\e;;ed I,, be the best strain in degrading PAHs. The experimental results have led to a model
conccl~t desclibing I'AHs degradation
Performance Analysis of Mobile Ad Hoc Network Routing Protocols Using ns-3 Simulations
Mobile ad hoc networks (MANETs) consist of mobile nodes that can communicate with each other through wireless links without reliance on any infrastructure. The dynamic topology of MANETs poses a significant challenge for the design of routing protocols. Many routing protocols have been developed to discover routes in MANETs through various mechanisms such as source, distance vector, and link state routing. In this thesis, we present a comprehensive performance comparison of several prominent MANET routing protocols. The protocols studied are Destination-Sequenced Distance-Vector (DSDV), Optimized Link State Routing (OLSR), Ad Hoc On-Demand Distance Vector protocol (AODV), and Dynamic Source Routing (DSR). We consider a range of network dynamicity and node density, model three mobility models: Steady-State Random Waypoint (SS-RWP), Gauss-Markov (G-M), and Lévy Walk, and use ns-3 to evaluate their performance on metrics such as packet delivery ratio, end-to-end delay, and routing overhead. We believe this study will be helpful for the understanding of mobile routing dynamics, the improvement of current MANET routing protocols, and the development of new protocols
Dynamic routing discovery scheme for high mobility in mobile ad hoc wireless networks
An innovative technology that is widely used in many applications is the Mobile Ad-hoc Network (MANET). Discovery and maintenance of routes at MANET are important issues. Within MANET, broadcasting is used to discover a path within on-demand routing protocols. Establishing and maintaining a route periodically among the nodes is the challenge that requires the transmitting of control packets across a network. This state leads to the issue of broadcasting storms. Broadcasting control packets increase control packets overhead and decrease network performance. In this paper, we proposed a scheme called AODV-Velocity and Dynamic (AODV-VD) for effective broadcast control packets. The routing protocol for the ad-hoc on-demand distance victor (AODV) is used to implement the proposed AODV-VD scheme. AODV-VD scheme reduces both the excessive route discovery control packets and network overhead. Network simulator version 2.35 (NS2.35) was used to compare the proposed AODV-VD scheme to the AODV routing protocol in terms of end-to-end latency, average throughput, packet transmission ratio and overhead ratio
Internet of Unmanned Aerial Vehicles: QoS Provisioning in Aerial Ad-Hoc Networks
Aerial ad-hoc networks have the potential to enable smart services while maintaining communication between the ground system and unmanned aerial vehicles (UAV). Previous research has focused on enabling aerial data-centric smart services while integrating the benefits of aerial objects such as UAVs in hostile and non-hostile environments. Quality of service (QoS) provisioning in UAV-assisted communication is a challenging research theme in aerial ad-hoc networks environments. Literature on aerial ad hoc networks lacks cooperative service-oriented modeling for distributed network environments, relying on costly static base station-oriented centralized network environments. Towards this end, this paper proposes a quality of service provisioning framework for a UAV-assisted aerial ad hoc network environment (QSPU) focusing on reliable aerial communication. The UAV’s aerial mobility and service parameters are modelled considering highly dynamic aerial ad-hoc environments. UAV-centric mobility models are utilized to develop a complete aerial routing framework. A comparative performance evaluation demonstrates the benefits of the proposed aerial communication framework. It is evident that QSPU outperforms the state-of-the-art techniques in terms of a number of service-oriented performance metrics in a UAV-assisted aerial ad-hoc network environment
Multipoint Relay Selection based on Stability of Spatial Relation in Mobile Ad hoc Networks
Increasing stability is one of the main objectives in designing routing protocols for Mobile Ad-Hoc Network (MANETS). Various research schemes have been addressed to this challenge and to support it. In fact, some papers have considered modifications to MPRs selection mechanism in OLSR. In this paper, the author proposes a new mechanism to elect stable and sustainable nodes relay between all nodes in MANETs. In this mechanism, a mobility function is used as the main selection criterion based on the calculation of the spatial relation of a node relative to its neighbor. This mechanism is applied in OLSR protocol to choose stable and supportable MPRs nodes. This mechanism significantly finds more stable MPRs and it promises QoS metrics such as lost packets and delay. Simulation results reveals a significant performance gains and it motivates further examinations to develop the mechanism in order to improve the routing protocol requirements. Performances are evaluated based on Random Waypoint model and network simulator ns3
A Hybrid (Active-Passive) VANET Clustering Technique
Clustering serves a vital role in the operation of Vehicular Ad hoc Networks (VANETs) by continually grouping highly mobile vehicles into logical hierarchical structures. These moving clusters support Intelligent Transport Systems (ITS) applications and message routing by establishing a more stable global topology. Clustering increases scalability of the VANET by eliminating broadcast storms caused by packet flooding and facilitate multi-channel operation. Clustering techniques are partitioned in research into two categories: active and passive. Active techniques rely on periodic beacon messages from all vehicles containing location, velocity, and direction information. However, in areas of high vehicle density, congestion may occur on the long-range channel used for beacon messages limiting the scale of the VANET. Passive techniques use embedded information in the packet headers of existing traffic to perform clustering. In this method, vehicles not transmitting traffic may cause cluster heads to contain stale and malformed clusters. This dissertation presents a hybrid active/passive clustering technique, where the passive technique is used as a congestion control strategy for areas where congestion is detected in the network. In this case, cluster members halt their periodic beacon messages and utilize embedded position information in the header to update the cluster head of their position. This work demonstrated through simulation that the hybrid technique reduced/eliminated the delays caused by congestion in the modified Distributed Coordination Function (DCF) process, thus increasing the scalability of VANETs in urban environments. Packet loss and delays caused by the hidden terminal problem was limited to distant, non-clustered vehicles. This dissertation report presents a literature review, methodology, results, analysis, and conclusion
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