D. K. Lobiyal

Dynamic User Preference Based Network Selection for Vertical Handoff in Heterogeneous Wireless Networks

In Heterogeneous Wireless Networks (HWN), seamless Vertical Handoff (VHO) to the best available network is significant in providing Quality of Experience to the Mobile Users. The selection of best available network is based on multiple contrasting handoff decision attributes along with their respective User Preferences. In literature, the user preferences used in various network selection techniques are pre-fixed i.e. static and arbitrary without any standard theoretical basis. This paper proposes a method to moderate these static user preferences on real time basis according to the current value of respective handoff decision attributes, to make them dynamic and realistic. The effect of Dynamic User Preferences on network selection for vertical handoff, is evaluated with the prominent Multi Attribute Decision Making (MADM) methods like Simple Additive Weighting, Multiplicative Exponential Weighting, Technique of Order Preference Similarity to Ideal Solution, and Grey Relational Analysis. Simulations are performed using both static user preference weights from the user and proposed dynamic user preference weights. The result of simulations shows that the number of vertical handoffs, needs to complete an application by a mobile user, using dynamic user preference weights is less in comparison to using static user preference weights for all considered MADM methods. This proves the effectiveness of the proposed dynamic user preferences in network selections to perform VHOs in HWNs.

Energy based proficiency analysis of ad-hoc routing protocols in wireless sensor networks

In a densely deployed sensor node network, each sensor nodes sense data and transmit it to a particular sink through multi-hop communications. Sensor nodes deployed nearby the sink node need to convey some extra data and control packets and therefore undergo much quicker energy depletion rates and so they have considerably smaller lifespan. This may discontinue network from functioning for a long time. Herein, we have analyzed the lifetime of sensor networks by using AODV, DSR, DYMO and ZRP protocol under different node density. Network Lifetime, throughput, energy consumption analysis, Average end to end delay, work efficiency, packet delivery ratio and packet latency (jitter) of each protocol has been demonstrated. The research of the usefulness of some prevailing methodologies towards lifespan estimation of sensor network has been carried out and simulation results are used to confirm the analysis. Behavior of protocols is observed under different energy models like generic, mica-motes and micaz. ZRP protocol consumes maximum energy under generic model and least energy under Micaz model. Average energy consumption is highest for generic model. For small number of nodes jitter of DYMO is more while for large number of nodes ZRP produces maximum jitter. DYMO produces maximum end to end delay while AODV produces minimum delay. Micaz model give maximum lifetime to a network. Energy consumption in transmission and receiving is highest for generic model. Throughput, work efficiency and packet delivery ratio is highest for DSR protocol.

Game Theory for Vertical Handoff Decisions in Heterogeneous Wireless Networks: A Tutorial

Heterogeneous wireless network (HWN) is an overlay structure of different wireless networks (WN). The WNs may differ in terms of coverage, capacity, underlying technology, service types, and network operators. In such a HWN environment, a mobile user (MU) equipped with multi-mode or multi-home terminal always wish to maintain connectivity with a wireless network which can provide best quality of experience (QoE). Similarly, the WN may allow the connectivity only to a MU which can provide highest revenue. This may leads to an event, called vertical handoff, where the MU leaves current WN and connect to another different WN. The conflicting goals of maximizing QoE and revenue simultaneously while performing a VHO necessitates the selection of mutually best MU and WN. Game theory is an efficient mathematical tool to model such situations where specific actions of decision makers lead to mutually conflicting consequences to each other. This paper, using a tutorial style, presented the game theory concepts and its application for VHO, type of games, and game solutions. It proposes, in specific, the noncooperative game formulations for three different VHO situations and their solutions using NASH for HWNs.

Semantic and keyword based web techniques in information retrieval

Semantic and keyword web based technique is becoming a generic issue in an application of Information Retrieval (IR). Most of the researchers used different web techniques for finding relevant information and find the keyword based search, which are not able to fetch the relevant search result because they do not know the actual meaning of the term or expression and relationship between them in the web search. In this paper, semantic and keyword based web search method have been applied on the different web search engines. The selected search engines such as semantic search engines (Google, Yahoo, Wikipedia) and keyword search engines (Hakia, Bing, DuckDuckGo). Performance is based on their precision ratio and natural language queries. Various queries was input on different search engine and output of the documents was classified a relevant documents and non-relevant documents. Precision ratios were calculated in the final retrieved documents on each web search engines. Also defined some popular semantic and keyword search engine features.

Multi-Gateway-Based Energy Holes Avoidance Routing Protocol for WSN

In wireless sensor networks (WSNs), efficient energy conservation is required to prolong the lifetime of the network. In this work, we have given emphasis on balanced energy consumption and energy holes avoidance. This paper proposes a multi-gateway-based approach to reduce the transmission distance between the sender and the sink node. The area to be monitored is divided into regions and gateway nodes are deployed at optimal positions. We have designed a transmission scheme, in which sensors in the sink region communicate directly to the sink, sensors in the gateway region communicate directly to the gateway, and sensors in the cluster region transmit their data directly to their respective cluster head which transmits data to the gateway in its region. If the distance between a cluster head and the sink is less than the distance between the cluster head and the gateway node, the cluster head transmits data to the sink instead of the gateway node. We have compared the proposed protocol with Low-Energy Adaptive Clustering Hierarchy (LEACH), Gateway Based Energy Aware Multi-Hop Routing (M-GEAR), and Gateway Based Stable Election Protocol (GSEP) protocols. The protocol performs better than other protocols in terms of throughput, stability period, lifetime, residual energy, and the packet transmitted to the sink.

Concepts extraction for medical documents using ontology

In the biomedical domain large amount of text documents are unstructured information is available in digital text form. Text Mining is the method or technique to find for interesting and useful information from unstructured text. Text Mining is also an important task in medical domain. The technique uses for Information retrieval, Information extraction and natural language processing (NLP). Traditional approaches for information retrieval are based on key based similarity. These approaches are used to overcome these problems; Semantic text mining is to discover the hidden information from unstructured text and making relationships of the terms occurring in them. In the biomedical text, the text should be in the form of text which can be present in the books, articles, literature abstracts, and so forth. Most of information is stored in the text format, so in this paper we will focus on the role of ontology for semantic text mining by using WordNet. Specifically, we have presented a model for extracting concepts from text documents using linguistic ontology in the domain of medical.

Dual Transmission Power and Ant Colony Optimization based Lifespan Maximization Protocol for Sensor Networks

A main characteristic of wireless sensor network WSN is its limited battery power. Non-uniform energy depletion in WSN, leads to formation of energy holes in certain areas of network. For a uniform consumption of energy among sensor nodes, some points should be considered like the residual energy of the nodes, energy consumed in the communication and route length. In this work, the authors has achieved the uniform consumption of energy by using dissimilar transmission power levels for communication between cluster heads and the sink node, and for intra-cluster communication. Further, they have used ant colony optimization technique for routing between the base station and sensors which are not the member of any cluster. They have proposed dual transmission power levels and ant colony optimization based DTP-ACO protocol to improve the lifespan of the network. Results demonstrate that DTP-ACO protocol outperforms LEACH protocol in provisions of the life span, residual energy, packets sent to the base station and throughput of the network.