M Tech Dissertations

Permanent URI for this collectionhttp://ir.daiict.ac.in/handle/123456789/3

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Subject: search.filters.subject.Asynchronous transfer mode

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Now showing 1 - 4 of 4
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    Traffic profile measurement and traffic driven network reconfiguration
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2011) Monga, Jasneet Kaur; Srivastava, Sanjay
    In multi hop ad hoc network, nodes are constrained by the power or the energy sources that are available. Efficient algorithms for saving the energy are required to manage the network in such a manner that the resources available, get properly utilized and nodes in the network do not drain out. Switching and working over idle and busy periods of a node, one can achieve this dual goal and it comes under the category of sleep scheduling. In this approach, the basic emphasis is on the traffic profiles of the network nodes which is estimated based on the network traffic flows. The traffic estimated becomes the weight of the path between the different source destination pairs available in the network and this value averaged either at the local level or the global level is needed to be reduced, hence saving the overall energy of the network. The traffic weighted paths which consume energy above the average or the threshold value become the prime candidates for the consideration. The aim is to go for shorter and lighter paths in the network which require the sleeping nodes in the proximity of heavy and longer paths to be awaken to be a part of network topology and saving the extra energy wasted on longer paths. This makes the nodes in longer paths go through a sleep state so that they can be utilized when they are required, hence making topology changes by reconfiguring the paths.
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    Fair downlink packet scheduling approach to support QoS in HSDPA environment
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2007) Singhal, Deepti; Jotwani, Naresh D.
    Traditionally, only best-effort traffic is supported by packet switching networks, but newer applications need communication services that allow end client to transport data with performance guarantees given in terms of data transfer reliability, available bandwidth and delay bounds. The choice of the packet-scheduling algorithm to be used at switching nodes is very crucial to provide the Quality of Service, QoS.

    This work aims at designing a downlink packet scheduling approach to QoS provisioning in High Speed Downlink Packet Access, HSDPA, based UMTS networks. In UMTS a single logical channel is shared among multiple contending users. Besides better link utilization, scheduling disciplines seek to achieve fair allocation of this shared resource. However, these two criterions can potentially be in conflict. In this work a scheduling discipline, \Wireless Fair - High Speed Scheduling", is proposed, which addresses the above-mentioned conflict. The idea is to allocate the channel fairly among users, even during short time scales, according to their data rate requirements.

    The proposed algorithm is compared with Adaptive Proportional Fair Algorithm, which provides fair distribution of channel bandwidth, proportional to the data rate requirements of users. Several experiments were conducted using simulation for comparing the performance of the algorithms in different scenarios. The results ensure that the proposed scheduling algorithm provides better link utilization, and long-term and short-term fairness among users even in heavy load conditions.

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    Packet scheduling algorithm to improve delay bounds in HSDPA
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2007) Pradhan, Pratik; Jotwani, Naresh D.
    With tremendous growth in mobile subscribers in recent past and trend of accessing packet data services in wireless networks, 3GPP has introduced an enhancement to Universal Mobile Telecommunications System (UMTS) standard known as High Speed Downlink Packet Access (HSDPA) to provide high data rate services, especially in the downlink. The main focus of HSDPA concept is to increase peak data rates, improve Quality of Service (QoS) and enhance the spectral efficiency for downlink packet data traffic. HSDPA introduces new transport channel named High Speed-Downlink Shared Channel (HS-DSCH) in downlink that is shared among the users accessing packet data services. Scheduling of these users is one of the most challenging and interesting problem because of constantly varying state of the wireless channel. The problem is even worse when users require certain level of QoS and the transmission rate supported by wireless channel is also varying. The Exponential Scheduling Algorithm, proposed in literature, is a good candidate to provide bounded delays when QoS requirements are speci¯ed in terms of maximum tolerable delays, but the investigations in this thesis show that it fails to provide delay bounds when it is still possible with some trade-o® with system throughput and sometimes not even that. The thesis proposes Delay Sense-Exponential Scheduling Algorithm, a variant of Exponential Scheduling Algorithm, to improve on the delay bounds provided by Exponential algorithm. The simulation results ensure that the new proposed algorithm improves on providing delay bounds to the Real Time (RT) services simultaneously providing comparable throughput to Non-Real Time (NRT) services. The proposed algorithm is studied under wide range of scenarios including NRT, RT and mixture of NRT and RT services.
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    Buffer aware routing in interplanetary ad hoc network
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2007) Mistry, Kamal; Srivastava, Sanjay; Lenin, R. B.
    Recent research has shown that existing TCP/IP protocol suit exhibits poor performance in space communication networks. To deal with communication challenges in deep space such as long propagation delay, high channel error rate, limited bandwidth etc. the architecture called Interplanetary Ad hoc Network (IPAN) is envisioned to establish a communication infrastructure in environment which allows to connect planets, natural and artificial satellites, and various mission elements such as space- crafts and rovers. The communication links in IPANs possess the properties of low bandwidth, high error rate, high latency and link unavailability for longer period of time. Nodes in such networks are resource constrained in terms of storage, energy and processing power. This work proposes a probabilistic routing protocol called \Buffer Aware Routing Protocol in Interplanetary Ad hoc Network (BARPIN)" based on the store and forward principle of Delay Tolerant Networking (DTN). Here IPAN is modeled as the network of two kinds of nodes, one having deterministic mobility patterns with greater resources and the others having random movement patterns with limited resources in terms of storage and energy. The delivery ratio performance measure of BARPIN is studied for different network conditions by changing field sizes, traffic rates, available resources on various nodes and for different source-destination pairs. Further we propose a model to estimate the minimum required buffer size of nodes for different data rates to reduce the packet loss due to buffer overflow, and justified the simulation results with analytical results.