Network

Orthogonal Frequency Division Multiplexing is a key contender for broadcasting standards, due to its immunity towards multipath fading and ease of implementation. Here a scheme to exploit the frequency diversity within OFDM subcarriers has been proposed which further increases the bit error rate performance. The diversity is achieved by circularly shifting the OFDM subcarrier coefficients in pseudorandom manner. Thus we notice a significant performance improvement without any additional bandwidth requirements.

With the progress of VLSI technology, delay buffer plays an important role affecting the circuit design and performance. This paper presents the design of low power buffer using clock gating and gated driver tree. Since delay buffers are accessed sequentially, it adopts a gated clock ring counter addressing scheme. The ring counter employs double edge triggered (DET) flip flops instead of traditional flip flop to half the operating frequency. Also for generating clock gating signals, combinational elements (C-element) are implemented in the control logic to avoid the increasing loading of the global clock signal. For the clock distribution network, a gated driver tree technique is used and it further reduces the power consumption. In addition, this technique is used in the input and output ports of the memory to decrease their loading. The proposed delay buffer consumes less power comparing to the conventional delay buffers.

Designing cost-efficient, secure network protocols for Wireless Sensor Networks (WSNs) is a challenging problem because sensors are resource-limited wireless devices. Resource limited in the sense limited energy level, memory and computational capacity. Since the communication cost is the most dominant factor in a sensor’s energy consumption. We introduce an Energy-Efficient Energy Based Encryption and Keying with Collision Avoidance scheme for WSNs that significantly reduces the number of transmissions needed for rekeying. This is done to avoid stale keys. Energy based encryption is a secure communication framework where sensed data is encoded using a scheme based on a permutation code generated by using the RC4 encryption mechanism. Dynamic keys are used for the packets in the stream. The intermediate nodes in the path verify the authenticity and integrity of the incoming packets. The key generated by the sender’s virtual energy, this avoids the rekeying. Energy based encryption efficiently transfers data between the nodes that are added in the watched list. Energy based encryption reduces transmission overhead. Transmission overhead increases if the packet size and also while transferring control messages for rekeying. During data transmission, if more than one node transmits data to same destination at same time the data gets collided at the receiving side. Retransmission reduces the energy level of the sensor node. While data is transmitted by first node and the next node must wait in queue until the first node completes its transmission. This mechanism avoids data collision in the destination and also it results in energy savings of a node because there is no need to transfer the same data again and again to the same destination if data collision occurs during transmission.

In MANETs, the Associativity Based Long-Lived Routing (ABR) protocol is an good alternative to the position-based and the location-aided routing protocols.In ABR, the associativity is determined by many factors such as residual battery life time, link stability, storage capacity, processing power and etc., In this paper we consider link stability to determine the associativity of the nodes. Link stability refers to how long any two nodes can communicate with each other. If a mobile host is in high mobility , there will be low stability. If there is low mobility, there will be high stability between any two nodes. Moblity causes frequent topology changes and can break the existing path. In this work, we use various mobility models like random waypoint(RWP) model, reference point group mobility(RPGM) and random direction mobility(RDM) models to study the performance of ABR protocol. These models capture the behaviors of ABR protocol in the simulator. The simulation results can show the performance of the ABR protocol varies based on the mobility models across different performance parameters.

The User Datagram Protocol (UDP) is one of the core members of the Internet Protocol Suite, the set of network protocols used for the Internet. With UDP, computer applications can send messages, in this case referred to as datagrams, to other hosts on an Internet Protocol (IP) network without requiring prior communications to set up special transmission channels or data paths. UDP uses a simple transmission model without implicit handshaking dialogues for providing reliability, ordering, or data integrity. Thus, UDP provides an unreliable service and datagrams may arrive out of order, appear duplicated, or go missing without notice. UDP assumes that error checking and correction is either not necessary or performed in the application, avoiding the overhead of such processing at the network interface level. Time-sensitive applications often use UDP because dropping packets is preferable to waiting for delayed packets, which may not be an option in a real-time system. The Internet has two main protocols in the transport layer, a connectionless protocol and a connection-oriented one. The connectionless protocol is UDP. The connection-oriented protocol is TCP. Because UDP is basically just IP with a short header added.

Using ad-hoc network a reliable technological condition has been provided for automatic Real-time monitoring and control of forest fires. This paper presents a new type of early warning systems which use a wireless sensor network to collect the information of forest fire, wireless sensor motes constitute microcontroller and zigbee protocol for smart monitoring and control the network through the self-organization of route.

Mobile ad-hoc networks operate in the absence of any supporting infrastructure. The absence of any fixed infrastructure in mobile ad-hoc networks makes it difficult to utilize the existing techniques for network services, and poses number of various challenges in the area. The discovery and maintenance of secure route is the most flinty challenge. In this thesis, we first deliberate and implement one secure routing protocol SAODV and study its performance under different scenarios. Then we carry out a number of experiments using NS-3 to compare the performance of AODV, SAODV in terms of security level and routing discovery time under different setups. From these experiments, we can see that performance of AODV and SAODV and Aridane.

In this paper we designed optical wired DWDM based OFDM design and simulation .The system whole setup is achieved by DWDM-OFDM for prefect SSMF optical wired communication (OFC) for 60 KM, using Due to increasing data traffic in network its required to design high effective spectral transmission. Here we implemented design with OFDM-DWDM due to own high spectral efficient property of 60 Gbps using 4- QAM.

This project aims to design a cluster-based multiprocessor system-on-chip (MPSoC) combines of hybrid interconnection composed of both bus based and network on chip (NOC) architecture. Two or more microprocessors working together to perform one or more related tasks using a shared memory is commonly referred to as a multiprocessor system. NoC is used to form a network to pass the message packets more efficiently between the source and destination and to provide additional communication resources so that multiple paths can be operated simultaneously. High performance is achieved by efficient implementation of hardware and software. It is done by fine tuning MPSoC architecture in the early stage of the design process. This project uses the FPGA device to prototype the cluster-based MPSoC. This paper proposes a hierarchical architecture consisting of SMP clustered nodes, each of which is structured by more than one baseline cores through centrally-shared memory and, some parallel applications with different characteristic of parallelism, functionality and communication pattern are designed and presented in this work. In this work a pure VHDL design, integrated with some intellectual property (IP) blocks. This project accounts for the highest throughput ratio.

Broadband and Wireless are the most common adoption in the communication market during the past ten years. Users want to be able to access to multimedia applications, data and voice while still using wireless mobility. To do so a high data rate is required. Moreover, multicasting is a tool used in networking which allows a selected group of users to receive the same information, and it is particularly useful for multimedia traffic. Obviously the research on the possible techniques to obtain such connection is a challenging topic in the field of mobile communication.The technological advances in wireless communications have enabled the realization of various systems which enable us to optimally use various multimedia applications. It is envisioned that many of the future wireless systems will incorporate considerable signal processing intelligence in order to provide advanced services such as multimedia transmission and detection. In general, wireless channels are hostile media to communicate, due to substantial physical impediments, primary radio frequency interference and time varying nature of the channel. The need of providing universal wireless access at high data- rate (which is the aim of many emerging wireless applications) presents a major technological challenge, and meeting this challenge necessities the development of advanced signal processing techniques for multiple- access communications in non- stationary interference rich environments. In this paper we present advanced signal processing methodologies for Multiple Access Interference (MAI) suppression in multiuser communication environment, while considering the transmission over Rayleigh fading channel. We also considered the effect of Doppler shift. A new model for realization of Rayleigh fading channel has been proposed. The statistical tests performed on the proposed channel were found satisfactory.