issues in manet

8/3/2019 Issues in MANET

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5.2 Issues in Ad Hoc Wireless Networks

Medium access schemeRoutingMulticastingTransport layer protocolPricing schemeQuality of service provisioningSelf-organization

SecurityEnergy managementAddressing and service discoveryScalability

Deployment considerations


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5.2.1 Medium Access Scheme

The primary responsibility of a MAC protocol in adhoc wireless network is the distributed arbitrationfor the shared channel for transmission of packetsMajor issues in medium access scheme Distributed operation Synchronization Hidden terminals, exposed terminals Throughput Access delay Fairness


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5.2.1 Medium Access Scheme (Cont.)Major issues in medium access scheme Real-time traffic support Resource reservation Ability to measure resource availability Capability for power control Adaptive rate control Use of directional antennas


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5.2.1 Medium Access Scheme (Cont.)

Distributed operations- Need to operate in environmentwhere No centralized coordination is possible.Synchronization- MAC Protocol design should take timesynchronization into account for TDMA based systems for Management and Transmission of slots.

Hidden Terminals- Nodes that are hidden from the sender of the data but reachable to the receiver.

Exposed Terminals- Nodes that are in the transmissionrange of the sender of the on-going session are prevented from

making transmission.Throughput- The MAC protocol used in adhoc wireless networkwant to maximize the throughput by minimizing the occurence of collision, Maximizing channel utilization, minimizing controloverhead.


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5.2.1 Medium Access Scheme (Cont.)

Access Delay- Average delay that any packet experience duringtransmission.

Fairness- Ability of MAC Protocol to provide an equal share of thebandwidth to all competing nodes.

Real Time Traffic Support- Supporting Time sensitive trafficsuch as voice, video and real time data requires explicit support fromMAC Protocol.Resource Reservation-Ability to measure Resource AvailabilityCapability for power controlAdaptive Rate Control- variation in the data bit rate achieved over thechannelUse of Directional Antennas- has advantages of increased spectrumreuse, reduction in interference, reduced power consumption.


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5.2.2 Routing

Routings responsibilities Exchanging the route information Finding a feasible path Gathering information about path breaks Mending the broken paths Utilizing minimum bandwidth

Major challenges for routing protocol Mobility Bandwidth constraint Error-prone and shared channel

Location-dependent contention


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5.2.2 Routing (Cont.)Major requirements of a routing protocol in ad hoc Minimum route acquisition delay Quick route reconfiguration Loop-free routing Distributed routing approach Minimum control overhead Scalability

Provisioning of QoS Support for time-sensitive traffic Security and privacy


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5.2.3 MulticastingMulticasting plays an important role in the typicalapplications of ad hoc wireless networks, namely,emergency search-and-rescue operations and militarycommunication

Provisioning of multiple links among the nodes in ad hocresults in a mesh-shaped structure

The major issues in designing multicast Robustness

Efficiency Control overhead Quality of service Efficient group management Scalability

Security


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5.2.4 Transport Layer Protocols

The main objectives of the transport layer protocolsinclude setting up and maintaining end-to-endconnections, reliable end-to-end delivery of datapackets, flow control, and congestion control


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5.2.5 Pricing Scheme

We need a pricing scheme for compensatingrelaying node for their consumption of resourcessuch as battery charge and computing power


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5.2.6 Quality of Service Provisioning

QoS is the performance level of services offeredby a service provider or a network to the user QoS parametersQoS-aware routingQos framework


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5.2.7 Self-Organization

One very important property that an ad hocshould exhibit is organizing and maintaining thenetwork by itself Major activities in self organization neighbor discovery topology reorganization topology organization


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5.2.9 Addressing and Service Discovery

Each device in ad hoc wireless network shouldhas unique addressWith unique address for each device, location of each device and whole network configurationcan be maintainedSo we can discover the node offering service


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5.2.10 Energy Management

Energy management can be classified intofollowing categories Transmission power management

Battery energy management Processor power management Devices power management


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5.2.11 Scalability

When size of ad hoc wireless network growingup, there are some problems such as install,latency, periodic routing overheadHierarchical topology system can improve thisproblem


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5.2.12 Deployment Considerations

The deployment of a commercial ad hoc wirelessnetwork has the following benefits comparing towired networks Low cost of deployment Incremental deployment Short deployment time Reconfigurability


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5.2.12 Deployment Considerations(Cont.)

Issues of considering deployment of ad hoc Scenario of deployment Required longevity of network Area of coverage Service availability Operational integration with other infrastructure Choice of protocols

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