Network

Orthogonal Frequency Division Multiplexing (OFDM) is regarded as one of the most outstanding multicarrier modulation technique in fourth generation (4G) wireless networks, which makes it possible to transfer very high bit rates despite extensive multipath radio propagation (echoes). The use of smart antenna arrays both at transmitter and receiver further increases the bit rate and enhance the system diversity on time variant and frequency selective channels resulting in a multiple-input multiple-output (MIMO) configuration. However one of the main disadvantages associated with MIMO-OFDM is the high Peak-to-Average Power Ratio (PAPR) of the transmitter’s output signal on different antennas. High Peak to Average Power Ratio (PAPR) for MIMO-OFDM system is still a demanding area and difficult issue. So far numerous techniques based on PAPR reduction have been proposed. In this paper a new method based on the combination of OSTBC Encoder andSpreading code sequence have been implemented and simulated. The results obtained are compared with earlier results based on transformtechniques.Simulations show that better results are obtained in proposed technique.

Multi-hop Wireless Networks (MHWNs) are anticipated to play an important role at the edge of the Internet, enabling a large number of innovative applications. The great demand for capacity from a large number of users and applications, coupled with the sparse bandwidth available on the wireless channel, place particular emphasis on effective congestion management approaches. Effective and well-studied algorithms for congestion control at the transport layer exist in wired networks. However, for a number of reasons, these approaches do not translate directly to wireless environments. In this chapter, we first describe the problem of congestion control in MHWNs, and discuss approaches for solving it. The presentation is organized into two components: (1) a review of the causes of congestion and algorithms for congestion avoidance in MHWNs at different layers of protocol stack; and (2) a review of analytical models for the rate control problem and their use for congestion control.

In this paper Game Theory is applied to the context of SYN flooding and modeled the game as a two-person non-cooperative zero sum game between the defender (web server administrator) and attacker (any malicious client). This is basically a static Bayesian game model. The elements of the payoff matrix are computed based on Erlang loss queuing cost model. The numerical illustrations are also provided.

The emerging Cognitive Technology promises to improve the network spectrum-utilization efficiency by allowing cognitive secondary users (SUs) to intelligently sense and opportunistically access those spectrum holes temporarily unused by license-holding primary users (PUs). Cognitive radios hold tremendous promise for increasing spectral efficiency in wireless systems. In this paper, we propose a cooperative spectrum sharing scheme between cellular network downlink and mobile ad-hoc network based on the analysis using stochastic geometry theory. The licensed spectrum belongs to the cellular network and the strong interference at cell-edge becomes a bottleneck to guarantee the quality of service requirement. In this case, the secondary ad-hoc users can assist the transmission between the base station and cell-edge mobile users in exchange for spectrum usage. Through maximizing the transmission capacity of secondary system under the constraint of throughput improvement of primary system, an optimal spectrum allocation can be obtained. Numerical and simulation results are provided to validate the analysis and verify the efficiency of the proposed scheme.

Vehicular Ad Hoc Networks (VANET) is a subclass of Mobile ad hoc networks which provides a distinguished approach for Intelligent Transport System (ITS). The survey of routing protocols in VANET is important and necessary for smart ITS. This paper discusses the advantages / disadvantages and the applications of various routing protocols for vehicular ad hoc networks. It explores the motivation behind the designed, and traces the evolution of these routing protocols. This paper discusses the main 5 types of protocols for VANET Topology Based, Positioned Based, Geo Cast, Broad Cast, Cluster Based Protocols.

MANETs use various anonymous routing protocols for hiding node identities and/or route identities from the outside observers in order to provide anonymity protection. Perhaps, existing anonymous routing protocols generate high cost or cannot offer complete anonymity protection to sources, destination and routes. To suggest high anonymity protection at a low cost, one of the proposed system is ALERT. ALERT energetically partitions the network field into zones and arbitrarily chooses nodes in zones as intermediate relay nodes, which form a nontraceable anonymous route. This partition process is called as hierarchical zone partition. In addition ALERT hides the data initiator or receiver among many initiators or receiver to reinforce the source as well as destination anonymity protection. Thus, ALERT offers anonymity protection to sources, destinations, and routes. It also has strategies to effectively encounter the intersection and timing attacks. Experimental results display stability with the theoretical analysis, and show that ALERT achieves better route anonymity protection in a low cost which it is compared with the other anonymous routing protocols.

The Next Generation Wireless Networks (NGWN) are heterogeneous in nature and Call Admission Control (CAC) in NGWN is a challenging problem. User differentiation is becoming increasingly important to the service providers as Quality of Service (QoS) requirements vary amongst users. The number of users in the network is directly controlled by CAC and hence must be carefully designed to guarantee the varying QoS needs of users. This paper proposes a channel partitioning model for CAC in NGWN by taking into account the users QoS needs and the simulation results for the call blocking probability of different user classes is presented.

Wireless ad-hoc networks allow the construction of flexible and adaptive networks with no fixed infrastructure or any base station. The core challenge is to develop efficient routing protocols for the dynamic nodes to commune with each other without any hazard or latency. A number of routing protocols such as Dynamic Source Routing (DSR), Ad Hoc on Demand Distance Vector Routing (AODV), Destination–Sequenced Distance Vector (DSDV) and Temporally Ordered Routing Algorithm (TORA) have already been presented for the communication purpose while AODV outperforms the others in terms of the efficiency. Considering several performance factors such as the packet delivery fraction (PDF), end to end delivery, normalized routing overload and the normalized MAC, this paper has proposed an improvement over the existing AODV protocol and termed it as I-AODV (improved AODV). Effectiveness of the proposed I-AODV algorithm under different level of nodal mobility is confirmed through Cygwin simulation.

Wireless Sensor Networks consists of spatially distributed autonomous sensors called nodes which co-operatively monitor a physical or environmental condition. Due to the scarce energy reserves in the sensor networks it is necessary to design protocols which minimize the energy consumption. In this paper, we firstly analyze the LEACH protocol in a homogeneous environment and then present a novel clustering based routing protocol for sensor networks. The simulation results show that the proposed protocol prolongs the network lifetime with 70% of the nodes remaining alive when compared to LEACH.

Cloud computing is clearly one of today’s most enticing technology areas due, at least in part, to its cost-efficiency and flexibility. However, despite the surge in activity and interest, there are significant, persistent concerns about cloud computing that are impeding momentum and will eventually compromise the vision of cloud computing as a new IT procurement model. In this paper, we characterize the problems and their impact on adoption. In addition, and equally importantly, we describe how the combination of existing research thrusts has the potential to alleviate many of the concerns impeding adoption. In particular, we argue that with continued research advances in trusted computing and computation-supporting encryption, life in the cloud can be advantageous from a business intelligence standpoint over the isolated alternative that is more common today