Network

Developing real time multimedia applications for best effort networks such as the Internet requires prohibitions against jitter delay and frame loss. This problem is further complicated in wireless networks as the rate of frame corruption or loss is higher in wireless networks while they generally have lower data rates compared to wired networks. On the other hand, variations of the bandwidth and the receiving device characteristics require data rate adaptation capability of the coding method. Multiple description Scalable Coding (MDS) methods are used to solve the jitter delay and frame loss problems by making the transmitted data more error resilient, however, this results in reduced data rate because of the added overhead. MDS methods do not address the bandwidth variation and receiver characteristics differences. In this paper a new method based on integrating MDS and the scalable coding extension of H.264 standard is proposed. Our method can handle both jitter delay and frame loss, and data rate adaptation problems. Our method utilizes motion compensating scheme and, therefore, is compatible with the current video coding standards such as MPEG-4 and H.264. Based on the simulated network conditions, our method shows promising results and we have achieved up to 38.3607dB for average Y-PSNR.

Jamming is defined as the act of intentionally directing electromagnetic energy towards a communication system to disrupt or prevent signal transmission. A jamming attacker launches jamming attacks easily by transmitting high-power signals and all legitimate sensor nodes interfered by jamming signals suffer corrupted packet transmissions. In this paper, model the interaction between the sensor network model and the attacker model as a non-cooperative non-zero-sum static game. In such a game, the sensor network has a set of strategies of controlling its probability of accessing the wireless channel and the attacker manipulates its jamming by controlling its jamming probability after sensing a transmission activity. The jammer action ceases when it is found by a monitoring node in the network, and an intimation of jamming message is transferred out of the jamming region. In this paper implements, algorithm for computing jamming attack and network defense. A critical issue is that there may exist a number of possible strategy profiles of Nash equilibria and its solve by applying Pareto-dominance and risk dominance.Results provide valuable insights about the structure of the jamming attack problem and associated defense policies and the adoption of sophisticated strategies on achieving desirable performance.

Mobile Ad-Hoc Networks (MANETs) uses security routing scheme for establishing secure route and securely data transmission. The security issues in MANET are mostly concentrated in two parts. The main security threat in MANET is integrity, non-repudiation and privacy. To combat with these security threats, many secure routing protocols has been designed to reduce the security threats in MANET. In this paper we have proposed Privacy Aware Routing Protocol (ESARP) to enhance the security levels in the routing protocol to prevent the network attacks. The proposed work consists of three parts. In the first part each node perform a key exchange operation with its one and two hop distance neighbours, in the second step, secure route establishment and in the third step, secure data communication is performed. Key exchange operation is done in two steps; in the first step, source node (S) exchanges public key (e) with its one hop distance nodes and establish a secret key (SK), and in the second step, source node exchanges public key with its two hop distance nodes and establish a secret key. On establishing the key exchange process node can participate in routing process. In route establishment process, secure route will be established between the sender and receiver. In the third step, sender and receiver will exchange their public key securely and establish a secret key for communication and then data communication is performed.

Today, the wide variety of devices in the digital world ranges from desktops to mobile phones. Within the currently available interactive multimedia applications, which are very demanding in terms of video quality and coding efficiency, the cost as well as the limited performances of scalability obtained in the current standards remains unacceptable. That is why; there is a need for intrinsically scalable video coding schemes providing fully progressive bit streams. Scalable Video Coding targets on seamless delivery of digital content and access to the same, enabling optimal user centered multi-channel and cross-platform media services, providing a straightforward solution for universal video delivery to a broad range of applications. Scalable video coding gives a nice way to perform rate shaping for video streams adapting to the available transmission resource. The work in this paper deals with a rate distortion approach in Scalable Video Coding in order to achieve a performance that is comparable to a non-scalable system. The rate distortion curves of the scaled video streams are employed to adapt to both static and dynamic channels. We consider a multiuser scenario which re?ects network heterogeneity and propose to perform a joint optimization between these multiple streams which have different performance curves.

Proxy blind signature combines the properties of both proxy signature and blind signature. In a proxy signature scheme, a signer delegates his signing power to a proxy, who signs a message on behalf of the original signer. In a blind signature scheme, the signer cannot link the relationship between the blind message and the signature of the chosen message. Therefore, it is very suitable for electronic commerce application. In this paper, a proxy blind signature scheme based on ECDLP for multiple signer has been proposed, which satisfy the security properties of both the blind signature and the proxy signature. In this proposed scheme multiple original signers are delegates their signing power to one proxy signer, who give signature on behalf of them. Analysis shows that our scheme is secure and efficient.

To satisfy the ever increasing network capacity, cellular systems should operate effectively with good grade of service (GoS) and quality of service (QoS). This paper proposes a quantitative approach to measuring the GoS and QoS performance of CDMA systems. It studies a realistic CDMA system operating in Nigeria and obtains empirical data from the field. A multi-dimensional Markov chain model is derived using related parameters and simulated under ideal conditions. The performance metrics of interest include blocking probability, handoff failure probability and weighted cost for GoS, and loss of communication quality for QoS. Simulation results show that effective link adaptation policies can greatly improve the system’s performance.

Transitioning IPv6 takes several challenges and hurdles. Significant work has been carried out to different transition scenarios to prove their suitability is under research. It is observed in the literature that the Internet infrastructure still has not significantly migrated from IPv4 to IPv6, even after the introduction of IPv6 in 1995. While IPv4 and IPv6 Internet infrastructures co-exists together, IPv4 mobile users should not be restricted to utilize only IPv4 based networks and IPv6 mobile users should not be restricted to utilize only IPv6 based networks. The current Internet protocols IPv4 and IPv6 adopted for the Mobile Internet connectivity provide facility for roaming of IPv4 mobile node into IPv4 based networks and facility for roaming of IPv6 mobile node into IPv6 based networks. This paper highlights the need of mobile Internet connectivity while roaming of IPv4 mobile node into IPv6 based networks and similarly while roaming of IPv6 mobile node into IPv4 based networks by providing inter-mobility and interoperability between IPv4 and IPv6 mobile nodes when they are in each other’s IP networks. This paper also emphasizes that more research have to be carried out, to design an integrated architecture addressing, inter-mobility and interoperability for IPv4 nodes in IPv6 networks and to design an integrated architecture addressing, inter-mobility and interoperability for IPv6 nodes in IPv4 networks.

One of the most important and challenging problems for seamless access of wireless and mobile services is mobility management, which will be regardless of the services and networks. Mobility management enables the Mobile (MT) to switch between networks for better resource management and is still a hot research topic. With so many handover algorithms available, how to evaluate and select the best algorithm becomes critical, thus making handover algorithms one of the essential components for the successful implementation of mobility. These algorithms need to be designed to provide the required Quality of Service (QoS) over a wide range of applications. This work is based on new criterion called Wrong Decision Probability (WDP) which is used to evaluate the performance of vertical handover algorithms and is based on signal strength (SS) and the available bandwidth (BW), which are combined together to obtain a better decision for handover. This paper proposes a new user centric algorithm for vertical handovers, which minimizes the wrong decisions during a handover process and maximize the user throughput by taking into account Bandwidth and Signal Strength of the network.

With the advent of OFDM for WLAN communications, as exemplified by IEEE 802.11a, it has become imperative to have efficient and reliable synchronization algorithms for OFDM WLAN receivers. The main challenges with synchronization deal with the delay spread and frequency offset introduced by the wireless channel. In this paper, research is done into OFDM WLAN synchronization algorithms, and a synchronizer implementation is presented. This synchronizer performs packet detection; frequency offset estimation, and time synchronization.

Designing of Very Large Scale Integrated Circuits (VLSI) operates at Megahertz and Gigahertz satisfying the design constraints for desired applications is a challenging job due to various reasons like transient time effect, high power requirement and consumption etc. Phase Locked Loop (PLL) is an important integrated circuit used in various areas of communications. Frequency synthesizers when used in Frequency Hopping Spread Spectrum (FH-SS) requires strict timing synchronization between transmitting and receiving system for successfully despreading and the power consumption is also high due to high frequency operation. In this contribution a new scheme has been proposed, in which frequency hopping transmitter and receiver has been operated at intermediate frequency and the same hopping rate was obtained as can be achieved by fast hopping spread spectrum operated at high frequency and therefore requires low speed frequency synthesizers and offers many advantages like more user capability, Low cost and simple amplifiers, filters, ADC and DAC converters requirement. The IFH-SS transmitter and receiver based on proposed intermediate frequency hopping spread spectrum has been experimentally verified. The results of experimental investigation have been presented in the paper. The waveforms obtained at various check nodes have also been presented.