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Increasing demand for high-performance 4G broadband wireless is done by the use of multiple antennas at both sides transmitting and receiving. Multiple antenna technologies allow high capacities suited for Internet and multimedia services, and also increase range and reliability of communication systems. Orthogonal frequency-division multiplexing (OFDM) is a popular method for high-data-rate wireless transmission over multipath fading. OFDM may be combined with multiple antennas at both the access point and mobile terminal to increase diversity gain and to enhance system capacity on a time-varying multipath fading channel, resulting a multiple-input multiple-output OFDM system. In this article, we describe a multiple input multiple output OFDM wireless communication system, with compressed technique i.e. Turbo Code. By this, increased capacity, coverage, and reliability of communication systems are clearly evident from the results presented in this article. Thus, the simulation resu...

Next generation wireless networks are envisaged to be an integration of different wireless networks and demand the ability of users to move from one network domain to another network domain seamlessly. Also these networks require superior handover techniques to provide ubiquitous access to roaming users with maximum network resource utilization. In order to fulfill these requirements, it is essential to select an appropriate time to initiate handover. The handover procedure can be completed before link down only if we have prior information about necessity of handover as well as availability of target network. The link down event and link up event provide information about handover requirement and resource availability respectively. In this paper, a predictive handover initiation mechanism is proposed to select an appropriate time to start handover procedure. Also the prediction initiation time is made adaptive to avoid link failure in high velocity applications which was fixed in c...

Mobile users are demanding anywhere and anytime access to high-speed data, real and non-real time multimedia services from wireless systems. Most of the wireless networks have been divided into independent layers and each layer has its specified job without any interaction. But for mobility management during handover (HO), layered architecture leads to inefficiency. So cross layer schemes are proposed for mobility management in wireless networks to improve HO performance in terms of delay, BW and QoS. This paper presents an overview of various cross layer mobility management (CLMM) techniques and also categorized them as Timely trigger based CLMM, Multi-entity based CLMM, Cross module based CLMM, Technology integration based CLMM, velocity-adaptive CLMM, and security enhanced CLMM considering the HO delay as performance metric. Each one of these techniques reduces HO delay but limited by some constraints related to real time applications. In this paper, a predictive LGD trigger sche...

In most of the wireless networks, signal strength is considered as the basic criteria to initiate handover. In future generation heterogeneous wireless systems, the vertical handover between different types of networks take place to satisfy demands of users. The location and velocity of mobile terminal is expected to be available in most of the modern systems. The time to reach boundary of serving cell named as Residual time is calculated using this information. The proposed mechanism makes use of signal strength and residual time to initiate handover. The threshold for residual time and hysteresis margin is determined to optimize vertical handover performance for different velocities. Simulation results show that the proposed mechanism improves handover efficiency in terms of handover rate and probability of call interruption.

Next generation wireless networks are envisaged to be an integration of different wireless networks and demand the ability of users to move from one network domain to another network domain seamlessly. Also these networks require superior handover techniques to provide ubiquitous access to roaming users with maximum network resource utilization. In order to fulfill these requirements, it is essential to select an appropriate time to initiate handover. The handover procedure can be completed before link down only if we have prior information about necessity of handover as well as availability of target network. The link down event and link up event provide information about handover requirement and resource availability respectively. In this paper, a predictive handover initiation mechanism is proposed to select an appropriate time to start handover procedure. Also the prediction initiation time is made adaptive to avoid link failure in high velocity applications which was fixed in c...

The integration of various cellular networks; wireless Local Area Networks, Worldwide interoperability for Microwave Access (WiMAX), Long Term Evolution (LTE), mobile ad-hoc networks and personal area networks utilizing all IP-based architecture constitutes 4G wireless networks. The mobile users roam across the boundaries of different access networks which gives rise to the requirement of effective handover algorithms. The basic criteria, while designing handover algorithms, is link quality, measured in terms of signal strength. In case of received signal strength based handover algorithms, the threshold signal strength and hysteresis margin play an important role. This paper gives an analysis of hysteresis margin for effective handover in 4G wireless networks. The impact of handover margin on handover delay and number of handovers is also investigated. Simulation results are obtained to find appropriate handover margin for users moving with different velocity.

In recent years the technology in the field of wireless networks has been advanced. The mobile users are demanding access to the wireless networks at anytime and anywhere. To ensure the service continuity and to maintain the promising QoS, the decision regarding handoff is to be taken appropriately. The most common criteria for handoff is received signal strength which is not sufficient in advanced networks. Thus, this paper reviews the multi-criteria based handoff decision algorithms in wireless networks. Different techniques for multi-criteria handover are also discussed.

Handover, a process of transferring connection of a mobile unit from an access point to another access point, is a challenging aspect in next generation cellular systems. The major difficulties experienced during handover between various technologies include high handover delay, large number of handovers and poor quality of service experienced by mobile users. This paper attempts to find an appropriate handover point in order to deal with handover related problems and to provide a promising quality to mobile users. The handover decision is taken on the basis of received signal strength and hysteresis margin. The variation of the received signal strength of current access point and the target access point with distance is followed to choose a suitable point for triggering handover. It is observed from the results obtained through Matlab simulation that the handover trigger point gets affected by variation in the hysteresis margin. In addition, the velocity of mobile users also has gr...

Vehicular networks are emerging technology that offers potential for providing a variety of new services. Vehicles are connected through Mobile IP but due high speed of vehicles mobile IP handover is a problem. The handover process, consisting of discovery, registration, and packet forwarding, has a large overhead and disrupts connectivity. With increased handover frequency and smaller access point dwell times in vehicular networks, the handover causes a large degradation in performance. This paper proposes a predictive handover solution, using a combination of a Kalman filter and hidden Markov model, to minimize the effects of prediction errors and to capitalize on advanced handover registration.To evaluate the effectiveness of the proposed methodMATLAB simulationsare carried out.Results show an overallimprovement in network performance with handover. Keywords-Vehicular Networks, Handover, Prediction FilterKalman filter, Hidden Markov Model (HMM),Forward Algorithm. I. INTRODUCTION ...

Today, most of the IT companies are moving towards Cloud infrastructure and technology due to its flexibility, scalability, and cost-effective features. But security is still the main hinderance to accept cloud computing on large scale. There are many security issues related to cloud implementation and one of the major threats is Distributed Denial of Services (DDoS) attack on cloud servers and applications. DDoS attack is a most prevailing security issue where attacker’s intention is to make all victim’s resources like cloud servers, storage, bandwidth etc. unavailable to general user which results to dissatisfactory outcomes in related business. This paper emphasis on understanding of DDoS attacks, their detection and analysis. The paper also explores the possible mitigation strategies to reduce the impact of DDoS.

This paper details information acquired from a secure shell honeypot, including plaintext login credentials and comprehensive attack data. As the number of data breaches and password leaks rises year after year, more dictionaries of reverse-engineered hashed passwords develop. Besides contributing to educational password dictionaries, this article also attempts to provide information about the geographical makeup of hackers encountered, as well as favored protocols. Its goal is to encourage developers to produce practical honeypot solutions for organizations with limited resources for their cyber-protection, as well as to encourage organizations to implement such measures and study their data. The low-interaction, user-friendly honeypot created is capable of running without manual intervention, and without interfering with parallelly running processes. Besides collecting login credentials used with SSH, in plaintext, its capabilities include recording, analyzing, and sending notific...

Multiple Input Multiple output Orthogonal Frequency division Multiplexing (MIMO-OFDM) is a prepossessing modulation technique that have achieve notable heed in wireless environment nowadays. It improves the bandwidth efficiency and increases system capacity so as to provide a reliable transmission. However it has a high increase in PAPR (peak-to-average power ratio) due to the use of large number of sub carriers which result in many restrictions for practical applications. A novel hybrid approach is presented in this paper for the PAPR reduction by merging PTS and clipping together. This paper consists of various technique for reducing peak-to-average power ratio that are developed in last two decades such as PTS, clipping, CMA etc. The simulation result shows a collation between different PAPR reduction techniques. We propose and demonstrate an algorithm using two different techniques together and the results are verified using MATLAB software. We also comment on the computational complexity and practicability of these approaches.