Showing papers in "ICTACT Journal on Communication Technology in 2010"
TL;DR: The classification suggested here summarizes the chief distinctiveness of many published proposals for energy efficient routing and the enhancements that can be done to improvise the existing routing protocols are pointed out.
Abstract: The routing in Mobile Ad Hoc Network (MANET) consumes huge amount of power and bandwidth and undergoes frequent topology changes to which it must adjust quickly. Energy efficient routing protocols have an important role in MANET. In this survey, few of the emerging energy efficient routing protocols for MANET are reviewed and their performance critically compared. The energy efficient protocols either minimize the active communication energy required to transmit or receive packets or minimize the inactive energy. The classification suggested here summarizes the chief distinctiveness of many published proposals for energy efficient routing. After getting insight into the different emerging energy efficient protocols, the enhancements that can be done to improvise the existing routing protocols are pointed out. The purpose of this paper is to facilitate the research efforts in combining the existing solutions to offer a more energy efficient routing mechanism.
9 citations
TL;DR: In this article, a new symmetric encryption algorithm is proposed that prevents the outside attacks, which avoids key exchange between users and reduces the time taken for the encryption and decryption.
Abstract: Hacking is one of the greatest problems in the wireless local area networks. Many algorithms have been used to prevent the outside attacks to eavesdrop or prevent the data to be transferred to the end-user safely and correctly. In this paper, a new symmetrical encryption algorithm is proposed that prevents the outside attacks. The new algorithm avoids key exchange between users and reduces the time taken for the encryption and decryption. It operates at high data rate in comparison with The Data Encryption Standard (DES), Triple DES (TDES), Advanced Encryption Standard (AES-256), and RC6 algorithms. The new algorithm is applied successfully on both text file and voice message.
8 citations
TL;DR: The network performance is estimated in terms of a quality of service (QoS) constraint given by the maximum tolerable bit error rate (BER) and optimal transmit power in presence of Rayleigh fading is derived.
Abstract: Design of an energy efficient wireless sensor network (WSN) has emerged as an important research area. Minimizing energy consumption is the primary objective for WSN. WSN is usually characterized by tiny size, low cost and low transmission power. So optimization of transmission power is of great importance. Optimal transmit power not only achieves better network lifetime but also reduces inter-node interference significantly. In this paper we carry out simulation studies to investigate the effects of Rayleigh fading on the performance of WSN and optimal transmit power in presence of Rayleigh fading is derived. The effects of bit rate and Rayleigh fading on optimal transmit power are investigated under several network conditions. In this paper the network performance is estimated in terms of a quality of service (QoS) constraint given by the maximum tolerable bit error rate (BER). The derived optimal transmit power maintains a minimum BER constraint. The impact of fading on critical bit rate i.e., the bit rate below which a desired BER can not be achieved with any amount of transmit power is also studied.
7 citations
TL;DR: The proposed approach is a speech enhancement method based on the spectral subtraction method, and the preprocessing is done by using partial differential equation, which provides a greater degree of flexibility and control on the noise subtraction levels that reduces artifacts in the enhanced speech, resulting in improved speech quality and intelligibility.
Abstract: Speech Enhancement can be used as a preprocessing technique in any of the speech communication systems. Speech communication involves a speaker, listener and communication device. The background noise present in the speech signal while transmitting has to be removed from the noisy speech signal to increase the signal intelligibility and to minimize the listener fatigue. The proposed approach is a speech enhancement method based on the spectral subtraction method, and the preprocessing is done by using partial differential equation. This method provides a greater degree of flexibility and control on the noise subtraction levels that reduces artifacts in the enhanced speech, resulting in improved speech quality and intelligibility. This method can be applied as a speech enhancement technique in Digital hearing aids, where sensor neural loss patients need 5dB to 10 dB higher SNR than normal hearing subjects.
7 citations
TL;DR: The hardware architecture of secure routing for wireless sensor networks is described and the results show that the data packets are secured and defend against the routing attacks with minimum energy consumption.
Abstract: Wireless Sensor Networks are extremely vulnerable to any kind of routing attacks due to several factors such as wireless transmission and resource-constrained nodes. In this respect, securing the packets is of great importance when designing the infrastructure and protocols of sensor networks. This paper describes the hardware architecture of secure routing for wireless sensor networks. The routing path is selected using Ad-hoc on demand distance vector routing protocol (AODV). The data packets are converted into digest using hash functions. The functionality of the proposed method is modeled using Verilog HDL in MODELSIM simulator and the performance is compared with various target devices. The results show that the data packets are secured and defend against the routing attacks with minimum energy consumption.
5 citations
TL;DR: A survey on WDM networks from its development to the current status is presented and an analysis on buffer size in optical networks for real time traffic was performed.
Abstract: Communication networks have emerged as a source of empowerment in today’s society. At the global level, the Internet is becoming the backbone of the modern economy. The new generations in developed countries cannot even conceive of a world without broadband access to the Internet. The inability of the current Internet infrastructure to cope with the wide variety and ever growing number of users, emerging networked applications, usage patterns and business models is increasingly being recognized worldwide. The dynamic growth of Internet traffic and its bursty nature requires high transmission rate. With the advances and the progress in Wavelength Division Multiplexing (WDM) technology, the amount of raw bandwidth available in fiber links has increased to high magnitude. This paper presents a survey on WDM networks from its development to the current status. Also an analysis on buffer size in optical networks for real time traffic was performed.
5 citations
TL;DR: The advantages and disadvantages of the combination of different protocols in the application layer and transport layer are analyzed and a combination of protocols for improving the network performance is arrived at, while retaining the QoS of video transmission.
Abstract: Video data transfer is the major traffic in today’s Internet. With the emerging need for anytime anywhere communication, applications transmitting video is gaining momentum. Real Time Protocol is the primary standard for transfer of video data, as; it requires timely delivery and can tolerate loss of packets. Streaming is the method used for delivering video content from the source server to the user. But this has many drawbacks: a) It sends only the amount of data equivalent to the streaming encoded rate to the client irrespective of the available bandwidth in the path. Hence the links are underutilized; b) It utilizes the link for the entire period of transfer and hence the link is not available to service other new clients. Thus as the number of clients increases, the network performance decreases. In this work, the advantages and disadvantages of the combination of different protocols in the application layer and transport layer are analyzed. The significant characteristics of each of these protocols are utilized and a combination of protocols for improving the network performance is arrived at, while retaining the QoS of video transmission.
5 citations
TL;DR: A pattern synthesis method is proposed based on modified Particle Swarm Optimization (PSO) algorithm and Differential Evolution (DE) algorithm to reduce sidelobe level while keeping the first null beamwidth (FNBW) fixed or variable.
Abstract: Reduction of sidelobe level in concentric ring arrays results in wide first null beamwidth (FNBW). Theauthors propose a pattern synthesis method based on modified Particle Swarm Optimization (PSO) algorithm and Differential Evolution (DE) algorithm to reduce sidelobe level while keeping the first null beamwidth (FNBW) fixed or variable. This is achieved by optimizing both ring spacing and number of elements in each ring of a concentric circular ring array of uniformly excited isotropic antennas. The first null beamwidth is attempted to be made equal to or less than that of a uniformly excited and 0.5 λ spaced concentric circular ring array of same number of elements and same number of rings. The comparative performance of modified Particle Swarm Optimization (PSO) algorithm and Differential Evolution (DE) algorithms based on this particular problem in terms of FNBW, sidelobe level and computational time is also studied.
4 citations
TL;DR: In this paper, the beam pattern of linear array antennas with isotropic elements is examined and a comparison is done between them for both symmetric as well as asymmetric arrays.
Abstract: In this paper, the beam pattern of Linear Array Antennas with isotropic elements is examined. The design goal is to reduce the sidelobe level with a minimum beamwidth increase for the far field radiation pattern of the array by varying its electrical as well as its physical configuration. In this paper the cases of a uniformly excited and uniformly spaced array, uniformly excited and non-uniformly spaced array, and a non-uniformly excited and uniformly spaced array are examined for both symmetric as well as asymmetric array, and a comparison is done between them. Real Coded Genetic Algorithm (RGA) is used to find the optimal locations as well as the optimal excitations for the problem as per the cases considered.
4 citations
TL;DR: A closed form solution for crosstalk is obtained by incorporating initial conditions using difference model approach for distributed RLCG interconnects and the SPICE simulation justifies the accuracy of the proposed approach.
Abstract: On chip interconnect plays a dominant role on the circuit performance in both analog and digital domains. Interconnects can no longer be treated as mere delays or lumped RC networks. Crosstalk, ringing and reflections are just some of the issues that need to be addressed for the efficient design of high speed VLSI circuits. In order to accurately model these high frequency effects, inductance had been taken into consideration. Within this frequency range, the most accurate simulation model for on-chip VLSI interconnects was the distributed RLC model. Unfortunately, this model has many limitations at much higher of operating frequency used in today’s VLSI design. This can lead to inaccurate simulations if not modeled properly. At even higher frequency the conductance metrics has become a dominant factor and has to be taken into consideration for accurate modeling of the different on-chip performance parameters. The traditional analysis of crosstalk in a transmission line begins with a lossless LC representation, yielding a wave equation governing the system response. With the increase in frequency and interconnection length due to the increase in the number of on-chip devices, the lossy components are prevailing than the lossless components. With the reduction of pitch between the adjacent wires in deep sub-micron technologies, coupling capacitances are becoming significant. This increase in capacitances results the introduction of noise which is capable of propagating a logical fault. An inaccurate estimation of the crosstalk could be the origin of the malfunction of the circuit. Cross talk can be analyzed by computing the signal linkage between aggressor and victim nets. The aggressor net carries a signal that couples to the victim net through the parasitic capacitances [13]. To determine the effects that this cross talk will have on circuit operation, the resulting delays and logic levels for the victim nets must be computed. This paper proposes a difference model approach to derive crosstalk in the transform domain. A closed form solution for crosstalk is obtained by incorporating initial conditions using difference model approach for distributed RLCG interconnects. We have proposed an explicit expression for the estimation of cross-talk noise. Our model considers both lossless components (i.e. L, C) and lossy components (i.e. R, G). The SPICE simulation justifies the accuracy of our proposed approach.
3 citations
TL;DR: A comparison of the performance of hard and soft-decision turbo coded Orthogonal Frequency Division Multiplexing systems with Quadrature Phase Shift Keying and 16-Quadrature Amplitude Modulation is considered, and a novel turbo decoding scheme for AWAN channel is proposed.
Abstract: A comparison of the performance of hard and soft-decision turbo coded Orthogonal Frequency Division Multiplexing systems with Quadrature Phase Shift Keying (QPSK) and 16-Quadrature Amplitude Modulation (16-QAM) is considered in the first section of this paper. The results show that the soft-decision method greatly outperforms the hard-decision method. The complexity of the demapper is reduced with the use of simplified algorithm for 16-QAM demapping. In the later part of the paper, we consider the transmission of data over additive white class A noise (AWAN) channel, using turbo coded QPSK and 16-QAM systems. We propose a novel turbo decoding scheme for AWAN channel. Also we compare the performance of turbo coded systems with QPSK and 16-QAM on AWAN channel with two different channel values- one computed as per additive white Gaussian noise (AWGN) channel conditions and the other as per AWAN channel conditions. The results show that the use of appropriate channel value in turbo decoding helps to combat the impulsive noise more effectively. The proposed model for AWAN channel exhibits comparable Bit error rate (BER) performance as compared to AWGN channel.
TL;DR: System performance measures like Complementary Cumulative Distribution Function (CCDF) of PAPR and bit error rate (BER) are analyzed through MATLAB simulation which proves the efficacy of the proposed pulse shaping scheme.
Abstract: OFDM is a form of multicarrier modulation technique with high spectral efficiency, robustness to channel fading, immunity to impulse interference, uniform average spectral density capacity of handling very strong echoes and non-linear distortion. Despite of its many advantages, one major disadvantage of OFDM is that the time domain OFDM signal which is a sum of several sinusoids leads to high peak to average power ratio (PAPR). The peak to average power ratio of the time domain envelope is an important parameter at the physical layer of the communication system using OFDM signaling. The signals must maintain a specified average energy level in the channel to obtain the desired Bit-error-rate. Pulse shaping techniques are very effective and mitigate problems associated with PAPR. In this paper conventional pulse shapes like Raised Cosine (RC), and sinc Power (SP) pulses are modified as Modified Raised Cosine Pulse (MRC) and Improved sinc Power pulse (ISP) introducing design parameter ‘d’ and amplitude parameter ‘a’ etc . The proposed method has fast decaying rate by decreasing the lobes of sinc function and its implementation complexity is also less. In this paper OFDM system performance measures like Complementary Cumulative Distribution Function (CCDF) of PAPR and bit error rate (BER) are analyzed through MATLAB simulation which proves the efficacy of the proposed pulse shaping scheme. It was observed from the performance curves using ISP pulse shaping filter at the OFDM transmitter’s end outperforms others.
TL;DR: A novel encryption scheme with time based key technique on an FPGA that ensures right key to be entered at right time and hence, vulnerability of encryption through brute force attack is eliminated.
Abstract: In this paper, a novel encryption scheme with time based key technique on an FPGA is presented. Time based key technique ensures right key to be entered at right time and hence, vulnerability of encryption through brute force attack is eliminated. Presently available encryption systems, suffer from Brute force attack and in such a case, the time taken for breaking a code depends on the system used for cryptanalysis. The proposed scheme provides an effective method in which the time is taken as the second dimension of the key so that the same system can defend against brute force attack more vigorously. In the proposed scheme, the key is rotated continuously and four bits are drawn from the key with their concatenated value representing the delay the system has to wait. This forms the time based key concept. Also the key based function selection from a pool of functions enhances the confusion and diffusion to defend against linear and differential attacks while the time factor inclusion makes the brute force attack nearly impossible. In the proposed scheme, the key scheduler is implemented on FPGA that generates the right key at right time intervals which is then connected to a NIOS – II processor (a virtual microcontroller which is brought out from Altera FPGA) that communicates with the keys to the personal computer through JTAG (Joint Test Action Group) communication and the computer is used to perform encryption (or decryption). In this case the FPGA serves as hardware key (dongle) for data encryption (or decryption).
TL;DR: A novel Scheduling Algorithm using Fuzzy logic and Ar networks that addresses both fairness and bandwidth allocation simultaneously is proposed and initial results show that a fair amount of fairness is attained while keeping the priority intact.
Abstract: During the last few years, users all over the world have become more and more familiar to the availability of broadband access. When users want broadband Internet service, they are generally restricted to a DSL (Digital Subscribers Line), or cable-modem-based connection. Proponents are advocating worldwide interoperability for microwave access (WiMAX), a technology based on an evolving s point-to multipoint wireless networking. Scheduling algorithms that support Quality of Service (QoS) differentiation and guarantees for wireless data networks are crucial to the deployment of broadband wireless networks. The performance affecting paramet fairness, bandwidth allocation, throughput, latency are studied found out that none of the conventional algorithms effectively for both fairness and bandwidth allocation simultaneously. Hence it is absolutely essential for an efficient scheduling algorithm with a better trade off for these two parameters. So we are proposing a novel Scheduling Algorithm using Fuzzy logic and Ar networks that addresses these aspects simultaneously. The initial results show that a fair amount of fairness is attained while keeping the priority intact. Results also show that maximum utilization is achieved with a negligible increment in processing time.
TL;DR: In this article, the authors proposed a fault localization algorithm for WDM networks which can identify the location of a failure on a failed lightpath and then attempt to reroute data stream through an alternate path.
Abstract: For several high speed networks, providing resilience against failures is an essential requirement. The main feature for designing next generation optical networks is protecting and restoring high capacity WDM networks from the failures. Quick detection, identification and restoration make networks more strong and consistent even though the failures cannot be avoided. Hence, it is necessary to develop fast, efficient and dependable fault localization or detection mechanisms. In this paper we propose a new fault localization algorithm for WDM networks which can identify the location of a failure on a failed lightpath. Our algorithm detects the failed connection and then attempts to reroute data stream through an alternate path. In addition to this, we develop an algorithm to analyze the information of the alarms generated by the components of an optical network, in the presence of a fault. It uses the alarm correlation in order to reduce the list of suspected components shown to the network operators. By our simulation results, we show that our proposed algorithms achieve less blocking probability and delay while getting higher throughput.
TL;DR: The performance of Low Density Parity Check codes with GMSK modulation (BT product=0.25) technique in Nakagami fading channel is demonstrated and it is shown that average bit error rate decreases as the ‘m’ parameter increases (Less fading).
Abstract: LDPC codes (Low Density Parity Check Codes) have already proved its efficacy while showing its performance near to the Shannon limit. Channel coding schemes are spectrally inefficient as using an unfiltered binary data stream to modulate an RF carrier that will produce an RF spectrum of considerable bandwidth. Techniques have been developed to improve this bandwidth inefficiency or spectral efficiency, and ease detection. GMSK or Gaussian-filtered Minimum Shift Keying uses a Gaussian Filter of an appropriate bandwidth so as to make system spectrally efficient. A Nakagami model provides a better explanation to less and more severe conditions than the Rayleigh and Rician model and provide a better fit to the mobile communication channel data. In this paper we have demonstrated the performance of Low Density Parity Check codes with GMSK modulation (BT product=0.25) technique in Nakagami fading channel. In results it is shown that average bit error rate decreases as the ‘m’ parameter increases (Less fading).
TL;DR: This paper proposes a MAC layer protocol denoted as Power Aware medium Access Control (PAMAC) protocol which enables the network layer to select a route with minimum total power requirement among the possible routes between a source and a destination provided all nodes in the routes have battery capacity above a threshold.
Abstract: Power consumption of nodes in ad hoc networks is a critical issue as they predominantly operate on batteries. In order to improve the lifetime of an ad hoc network, all the nodes must be utilized evenly and the power required for connections must be minimized. Energy management deals with the process of managing energy resources by means of controlling the battery discharge, adjusting the transmission power and scheduling of power sources so as to increase the lifetime of the nodes of an ad hoc wireless network. In this paper, two protocols are proposed to improve the lifetime of the nodes. The first protocol assumes smart battery packages with L cells and uses dynamic programming (DP) to optimally select the set of cells used to satisfy a request for power. The second one proposes a MAC layer protocol denoted as Power Aware medium Access Control(PAMAC) protocol which enables the network layer to select a route with minimum total power requirement among the possible routes between a source and a destination provided all nodes in the routes have battery capacity above a threshold. The life time of the nodes using the DP based scheduling policy is found through simulation and compared with that obtained using the techniques reported in the literature. It is found that DP based policy increases the lifetime of the mobile nodes by a factor of 1.15 to 1.8. The life expectancy, the average power consumption and throughput of the network using PAMAC protocol are computed through simulation and compared with that of the other MAC layer protocols 802.11, MACA, and CSMA. Besides this, the life expectancy and average power consumption of the network for different values of threshold are also compared. From the simulation results, it is observed that PAMAC consumes the least power and provides the longest lifetime among the various MAC Layer protocols. Moreover, using PAMAC as the MAC layer protocol, the performance obtained using different routing layer protocols are studied. It is observed that AODV consumes the least power and provides the longest lifetime.
TL;DR: A novel scheme is proposed which comprises of asynchronous pipelining techniques and the advantages of FPGAs for implementing a 200Mbps MB-OFDM UWB transmitter digital backend modules for four-phase bundled-data protocol.
Abstract: In this paper, a novel scheme is proposed which comprises the advantages of asynchronous pipelining techniques and the advantages of FPGAs for implementing a 200Mbps MB-OFDM UWB transmitter digital backend modules. In asynchronous pipelined system, registers are used as in synchronous system. But they are controlled by handshaking signals. Since FPGAs are rich in registers, design and implementation of asynchronous pipelined MBOFDM UWB transmitter on FPGA using four-phase bundled-data protocol is considered in this paper. Novel ideas have also been proposed for designing asynchronous OFDM using Modified Radix2 4 SDF and asynchronous interleaver using two RAM banks. Implementation has been performed on ALTERA STRATIX II EP2S60F1020C4 FPGA and it is operating at a speed of 350MHz. It is assured that the proposed MB-OFDM UWB system can be made to work on STRATIX III device with the operating frequency of 528MHz in compliance to the ECMA-368 standard. The proposed scheme is also applicable for FPGA from other vendors and ASIC.
TL;DR: An integrated mobility management protocol for IP based wireless networks is proposed and analyzed and results presented in this paper are based on ns 2.0.
Abstract: The success of next generation wireless networks will rely much on advanced mechanisms for seamless mobility support among emerging heterogeneous technologies. Currently, Mobile IP is the most promising solution for mobility management in the Internet. Several IP micro mobility approaches have been proposed to enhance the performance of Mobile IP which supports quality of service, minimum packet loss, limited handoff delay and scalability and power conservation but they are not scalable for macro mobility. A practical solution would therefore require integration of Mobile IP and Micro mobility protocols where Mobile IP handles macro mobility and micro mobility protocols handles micro mobility. In this paper an integrated mobility management protocol for IP based wireless networks is proposed and analyzed. Simulation results presented in this paper are based on ns 2.
TL;DR: This work presents an accurate and efficient model to compute the delay and slew metric of on-chip interconnect of high speed CMOS circuits foe ramp input based on the Burr’s Distribution function.
Abstract: This work presents an accurate and efficient model to compute the delay and slew metric of on-chip interconnect of high speed CMOS circuits foe ramp input. Our metric assumption is based on the Burr’s Distribution function. The Burr’s distribution is used to characterize the normalized homogeneous portion of the step response. We used the PERI (Probability distribution function Extension for Ramp Inputs) technique that extends delay metrics and slew metric for step inputs to the more general and realistic non-step inputs. The accuracy of our models is justified with the results compared with that of SPICE simulations.
TL;DR: In this paper, the authors presented a sequentially fed balanced amplifying antenna that exhibits circularly polarized radiation and achieved a good axial ratio of 2.4 GHz at 2.37 GHz frequency.
Abstract: This paper presents a sequentially fed balanced amplifying antenna that exhibits circularly polarized radiation. The inherent benefits of good isolation between input and output ports as well as improved matching capabilities of balanced amplifiers provide overall system gain of 8 dBi at frequency 2.36GHz. The planar arrangement of the patch antenna elements are considered to form an array. The phase of the feeding in the array increases progressively from 0 0 to 270 0 .Each element in the array is linearly polarized. Here four elements were considered and 2arranged at the four corners of a square domain. This arrangement shows that each antenna sees its adjacent ones to be radiating from an edge orthogonal to its edge of radiation. Circular polarization is achieved due to this sequential feeding. This array is designed with operating frequency 2.4 GHz. A good axial ratio of 2.4 is obtained at 2.37 GHz frequency. The noise figure is considerably reduced and which is around -19dB.
TL;DR: A mobile transaction framework in which mobile users can share data which is stored in the cache of a mobile agent which is a special mobile node which coordinates the sharing process.
Abstract: We present a mobile transaction framework in which mobile users can share data which is stored in the cache of a mobile agent. This mobile agent is a special mobile node which coordinates the sharing process. The proposed framework allows mobile affiliation work groups to be formed dynamically with a mobile agent and mobile hosts. Using short range wireless communication technology, mobile users can simultaneously access the data from the cache of the mobile agent. The data Access Manager module at the mobile agent enforces concurrency control using cache invalidation technique. This model supports disconnected mobile computing allowing mobile agent to move along with the Mobile Hosts. The proposed Transaction frame work has been simulated in Java 2 and performance of this scheme is compared with existing frame works.
TL;DR: Automatic segmentation methods for audio broadcast data are proposed using Auto Associative Neural Networks to segment the audio data into predefined categories using the extracted features.
Abstract: In this paper, we describe automatic segmentation methods for audio broadcast data. Today, digital audio applications are part of our everyday lives. Since there are more and more digital audio databases in place these days, the importance of effective management for audio databases have become prominent. Broadcast audio data is recorded from the Television which comprises of various categories of audio signals. Efficient algorithms for segmenting the audio broadcast data into predefined categories are proposed. Audio features namely Linear prediction coefficients (LPC), Linear prediction cepstral coefficients, and Mel frequency cepstral coefficients (MFCC) are extracted to characterize the audio data. Auto Associative Neural Networks are used to segment the audio data into predefined categories using the extracted features. Experimental results indicate that the proposed algorithms can produce satisfactory results.
TL;DR: This work proposes an adaptive scheme that makes use of an eligibility factor that is calculated based on the distance to the zone center, remaining battery power and average speed to elect a core node that change according to the network dynamics.
Abstract: Providing efficient and scalable service provisioning in Mobile Ad Hoc Network (MANET) is a big research challenge. In adaptive service provisioning mechanism an adaptive election procedure is used to select a coordinator node. The role of a service coordinator is crucial in any distributed directory based service provisioning scheme. The existing coordinator election schemes use either the nodeID or a hash function to choose the coordinator. In these schemes, the leader changes are more frequent due to node mobility. We propose an adaptive scheme that makes use of an eligibility factor that is calculated based on the distance to the zone center, remaining battery power and average speed to elect a core node that change according to the network dynamics. We also retain the node with the second highest priority as a backup node. Our algorithm is compared with the existing solution by simulation and the result shows that the core node selected by us is more stable and hence reduces the number of handoffs. This in turn improves the service delivery performance by increasing the packet delivery ratio and decreasing the delay, the overhead and the forwarding cost.
TL;DR: The proposed Provisioning Restorable Virtual Private Networks Algorithm (PRA) is used to combine the provisioning and restoration algorithms to achieve better results than the ones obtained by independent restoration and provisioning.
Abstract: As internet usage grows exponentially, network security issues become increasingly important. Network security measures are needed to protect data during transmission. Various security controls are used to prevent the access of hackers in networks. They are firewall, virtual private networks and encryption algorithms. Out of these, the virtual private network plays a vital role in preventing hackers from accessing the networks. A Virtual Private Network (VPN) provides end users with a way to privately access information on their network over a public network infrastructure such as the internet. Using a technique called “Tunneling”, data packets are transmitted across a public routed network, such as the internet that simulates a point-to-point connection. Virtual private networks provide customers with a secure and low-cost communication environment. The basic structure of the virtual circuit is to create a logical path from the source port to the destination port. This path may incorporate many hops between routers for the formation of the circuit. The final, logical path or virtual circuit acts in the same way as a direct connection between the two ports. Our proposed Provisioning Restorable Virtual Private Networks Algorithm (PRA) is used to combine the provisioning and restoration algorithms to achieve better results than the ones obtained by independent restoration and provisioning. In order to ensure service quality and availability in Virtual Private Networks, seamless recovery from failures is essential. The quality of service of the Virtual Private Networks is also improved due to the combination of provisioning and restoration. The bandwidth sharing concept is also applied in link to improve the quality of service in the Virtual Private Network. The performance analysis of the proposed algorithm is carried out in terms of cost, the number of nodes, the number of VPN nodes, delay, asymmetric ratio and delay with constraints with Disjoint Path Algorithm and Approximation Restoration Virtual Private Networks Algorithm. The Provisioning Restorable Virtual Private Networks Algorithm performs better than the Disjoint Path Algorithm.
TL;DR: A coexistence model of IEEE 802.15.4 and IEEE802.11b networks is proposed, which attend to their coexistence behavior and explain their coexist performance.
Abstract: The recurrent collocation of IEEE 802.15.4 Wireless Sensor Networks (WSNs) and IEEE 802.11b Wireless Local Area Networks (WLANs) consequence in coexistence issues, as these networks share the same 2.4GHz Industrial, Scientific, and Medical (ISM) band. As a result, their performance may degrade. We have proposed a coexistence model of IEEE 802.15.4 and IEEE 802.11b networks, which attend to their coexistence behavior and explain their coexistence performance. The packet error rate (PER) of the IEEE 802.15.4 under the interference of the IEEE 802.11b is taken as a foremost performance measure , and is obtained from the bit error rate (BER). The signal to noise and interference ratio is used to calculate the BER. The minimum distance between IEEE 802.15.4 and IEEE 802.11b is observed from the PER. Throughput, average end-end delay and average jitter is used as performance measures to analyze the performance of IEEE802.15.The methodical results are validated for various topologies with and without mobility model using Qualnet 4.5 simulation.
TL;DR: This work proposes a new efficient AQM (Active Queue Management) scheme known as Exponential Random Early Detection (E-RED) to reduce the packet loss even at more congestion time and shows that the proposed approach E-RED outperforms RED.
Abstract: In today’s globally integrated Emerging technologies, the current Internet protocols uses packet-level mechanisms having end to end links to detect and react to congestion. But the regulation of best-effort traffic and congestion control is largely left to the Queue Management. Drop-tail, Random Early Detection (RED) and Random Exponential Marking are quite effective in reducing packet losses under certain level of congestion and are insufficient to ensure overall network stability. At times of high congestion, not only does the end user experience very poor performance, but also a lot of network resource is wasted due to retransmissions and aborted connections. Hence, it is required to propose a new efficient AQM (Active Queue Management) scheme known as Exponential Random Early Detection (E-RED) to reduce the packet loss even at more congestion time. The proposed probability calculation approach for congestion control in an ERED framework is implemented with probability marking capabilities. We had implemented ERED algorithm and compared with the RED algorithm during packet loss in congestion control at various time intervals. The experimental result shows that our proposed approach E-RED outperforms RED. The experimental result also shows the packet loss for the nodes at various time intervals, Queue sizes and bandwidth.
TL;DR: A MAC protocol with two spectrum sensing schemes, namely Fusion based Arbitrary sensing scheme and Intelligence based sensing scheme are analyzed including the effects of interference and it is found that interference affects the sensing efficiency which in turn affects the throughput of the cognitive radio users.
Abstract: Cognitive Radio technology is a novel and effective approach to improve utilization of the precious radio spectrum. Spectrum sensing is one of the essential mechanisms for cognitive radio (CR) and various sensing techniques are used by the secondary users to scan the licensed spectrum band of the primary radio (PR) users to determine the spectrum holes. These can be intelligently used by the secondary users also referred to as CR users, for their own transmission without causing interference to the PR users. In this paper, a MAC protocol with two spectrum sensing schemes, namely Fusion based Arbitrary sensing scheme and Intelligence based sensing scheme are analyzed including the effects of interference. Rayleigh channel model for PR-PR interference and CR-PR interference is considered. An expression for the aggregate throughput of the cognitive radio network is derived for the two channel sensing schemes. The effects of interference on throughput are studied both by analysis and by simulation. It is found that interference affects the sensing efficiency which in turn affects the throughput of the cognitive radio users. Rate Adaptation techniques are further employed to enhance the cognitive radio network throughput.
TL;DR: This paper presents the design details of a distributed defense mechanism against DDoS attack, the egress routers of the intermediate network coordinate with each other to provide the information necessary to detect and respond to the attack.
Abstract: Distributed Denial of service is a major threat to the availability of internet services. Due to the distributed, large scale nature of the Internet makes DDoS (Distributed Denial-of-Service) attacks stealthy and difficult to counter. Defense against Distributed Denialof Service attacks is one of the hardest security problems on the Internet. Recently these network attacks have been increasing. Therefore more effective countermeasures are required to counter the threat. This requirement has motivated us to propose a novel mechanism against DDoS attack. This paper presents the design details of a distributed defense mechanism against DDoS attack. In our approach, the egress routers of the intermediate network coordinate with each other to provide the information necessary to detect and respond to the attack. Thus, a detection system based on single site will have either high positive or high negative rates. Unlike the traditional IDSs (Intrusion Detection System) this method has the potential to achieve high true positive ratio. This work has been done by using consensus algorithms for exchanging the information between the detection systems. So the overall detection time would be reduced for global decision making.