2,180 research outputs found
QoS in Node-disjoint Routing for Ad Hoc Networks
PhDA mobile ad hoc network (MANET) is a collection of mobile nodes that
can communicate with each other without using any fixed infrastructure.
It is necessary for MANETs to have efficient routing protocol and quality
of service (QoS) mechanism to support multimedia applications such as
video and voice.
Node-Disjoint Multipath Routing Protocol (NDMR) is a practical protocol
in MANETs: it reduces routing overhead dramatically and achieves
multiple node-disjoint routing paths.
Because QoS support in MANETs is important as best-effort routing is
not efficient for supporting multimedia applications, this thesis presents a
novel approach to provide that support.
In this thesis NDMR is enhanced to provide a QoS enabled NDMR that
decreases the transmission delay between source and destination nodes.
A multi-rate mechanism is also implemented in the new protocol so that
the NDMR QoS can minimise the overall delays. It is shown that these
approaches lead to significant performance gains. A modification to
NDMR is also proposed to overcome some of the limitations of the
original
Multipath routing and QoS provisioning in mobile ad hoc networks
PhDA Mobile Ad Hoc Networks (MANET) is a collection of mobile nodes that can
communicate with each other using multihop wireless links without utilizing any
fixed based-station infrastructure and centralized management. Each mobile node
in the network acts as both a host generating flows or being destination of flows
and a router forwarding flows directed to other nodes.
Future applications of MANETs are expected to be based on all-IP
architecture and be capable of carrying multitude real-time multimedia
applications such as voice and video as well as data. It is very necessary for
MANETs to have an efficient routing and quality of service (QoS) mechanism to
support diverse applications.
This thesis proposes an on-demand Node-Disjoint Multipath Routing protocol
(NDMR) with low broadcast redundancy. Multipath routing allows the
establishment of multiple paths between a single source and single destination
node. It is also beneficial to avoid traffic congestion and frequent link breaks in
communication because of the mobility of nodes. The important components of
the protocol, such as path accumulation, decreasing routing overhead and
selecting node-disjoint paths, are explained. Because the new protocol
significantly reduces the total number of Route Request packets, this results in an
increased delivery ratio, smaller end-to-end delays for data packets, lower control
overhead and fewer collisions of packets.
Although NDMR provides node-disjoint multipath routing with low route
overhead in MANETs, it is only a best-effort routing approach, which is not
enough to support QoS. DiffServ is a standard approach for a more scalable way
to achieve QoS in any IP network and could potentially be used to provide QoS
in MANETs because it minimises the need for signalling. However, one of the
biggest drawbacks of DiffServ is that the QoS provisioning is separate from the
routing process. This thesis presents a Multipath QoS Routing protocol for
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supporting DiffServ (MQRD), which combines the advantages of NDMR and
DiffServ. The protocol can classify network traffic into different priority levels
and apply priority scheduling and queuing management mechanisms to obtain
QoS guarantees
Multipath optimized link state routing for mobile ad hoc networks
International audienceMultipath routing protocols for Mobile Ad hoc NETwork (MANET) address the problem of scalability, security (confidentiality and integrity), lifetime of networks, instability of wireless transmissions, and their adaptation to applications. Our protocol, called MP-OLSR (MultiPath OLSR), is a multipath routing protocol based on OLSR. The Multipath Dijkstra Algorithm is proposed to obtain multiple paths. The algorithm gains great flexibility and extensibility by employing different link metrics and cost functions. In addition, route recovery and loop detection are implemented in MP-OLSR in order to improve quality of service regarding OLSR. The backward compatibility with OLSR based on IP source routing is also studied. Simulation based on Qualnet simulator is performed in different scenarios. A testbed is also set up to validate the protocol in real world. The results reveal that MP-OLSR is suitable for mobile, large and dense networks with large traffic, and could satisfy critical multimedia applications with high on time constraints
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. 377.1ïżœ781.8ïżœ781ïżœ+
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
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