Earticle

The delay and dispersion of the packet train have been widely used in most network measurement tools. The timestamp of the packet is critical for the measurement accuracy. However, timestamping performed either in the application or the kernel layer would be easily affected by the source and destination hosts especially in high-speed network. Therefore, to evaluate the impact of the timestamp precision on the measurement, a high accuracy timestamping hardware system (HATS) based on NetFPGA was designed and implemented. With HATS, the deviation of timestamp accuracy among the application, the kernel and the hardware layers was analyzed.

Total exchange or all-to-all personalized communication problem is that each node in a network has a message to be sent to every other node. To solve this communication problem, we present a time-optima algorithm in anonymous Cayley graphs as assuming a single-port full duplex model in which every node is able to send and receive at most one message in each time unit.

As deployment of sensor networks are recently expanding, a variety of services based on sensor network have been introduced. Nevertheless, problems such as network bandwidth reduction, collision occurrence and performance deterioration due to broadcasting of message in large scale networks have become main challenges. Above all, prolonging of battery lifetime becomes primary challenge to overcome for deploying sensor networks in various fields. In this paper, we present a new routing algorithm based on data-centric routing and address-based routing schemes, which is that query messages are delivered to target area by using address-based routing scheme, then, broadcast scheme is used in target area by inserting additional information of neighbor nodes into the message payload. This method prevents severe broadcast storm caused by broadcasting messages, and also provides reliable data delivery at reasonable level by utilizing address information in message. By computer simulation, our proposed scheme significantly reduces energy consumption caused by broadcasting of messages as well as it improves appropriate data reliability in wireless sensor networks.

Mobility of nodes is an important issue in mobile adhoc networks (MANET). Nodes in MANET move from one network to another individually and in the form of group. In single node mobility scheme every node performs registration individually in new MANET whereas in group mobility scheme only one node in a group i.e group representative (GR) performs registration on behalf of all other nodes in the group and is assigned Care of Address (CoA). Internet protocol (IP) of all other nodes in the group remains same. Our simulated results prove that group mobility scheme reduces number of messages and consumes less time for registration of nodes as compared to single node mobility scheme. Thus network load is reduced in group mobility scheme. This research paper evaluates the performance of group mobility with single node mobility scheme. Test bed for this evaluation is based on Network Simulator 2 (NS-2) environment.

Video sequence matching is the most crucial step to verify whether a video sequence has been copied from another or not. The video sequence in question is represented by a set of visual descriptors. Based on such descriptors the sequence has to be matched with the sequences present in the database. Thus, sequence matching becomes a crucial task. Furthermore, to evade the verification process, one may incorporate visual distortions in the original sequence to generate the copied version. Again, the copied sequence may be generated by taking few sampled frames or a part of the original sequence. Thus, the task of sequence matching becomes more challenging. In this work, rather than concentrating on the visual descriptors, we have focused on the technique of sequence matching that can sustain the challenges posed. We have proposed a hypothesis test based scheme for sequence matching which has inherent strength to withstand the said attacks considerably. Experimental result also indicates its capability of the scheme in doing so.

The use of mobile networks is rapidly increasing day by day. There are two aspects in mobile networks such as host mobility and network mobility. The protocols used for host mobility takes care of only single node to be connected with the internet. But, the protocols used for network mobility takes care of whole network to be connected with the internet using mobile router. The need for NEtwork MObility (NEMO) support is inevitable in mobile platforms such as car, bus, train, air-plane, etc. The Mobile Internet Protocol version 6 (MIPv6) and NEMO Basic Support Protocol (BSP) is used to support host mobility and network mobility, respectively. The NEMO BSP introduces several advantages, such as reduced signaling, increased manageability, reduced power consumption and conservation of bandwidth when compared to MIPv6 to be used in the mobile platforms. The NEMO BSP also suffers from a number of limitations, like inefficient route and increased handoff latency. The recent researches on NEMO have proposed several Route Optimization (RO) schemes that solves inefficient route. Though the proposed RO mechanisms solve inefficient route, it also has limitations such as signaling overflow, complexity and processing overload, delay during handoff, security breach, etc. The objectives of this survey are to identify, classify RO mechanisms and to select suitable RO mechanisms to enhance Quality of Service (QoS) in different kinds of internet applications.

One of today’s most important developing wireless technologies is Cognitive Radio (CR). In our current fixed-assignment spectrum management policy, much of the available frequencies go unused. CR aims to make use of this unutilized space to provide wireless broadband services. This paper aims to give a background to CR and describe the key players in standardization and allocation of the unused spectrum. Furthermore, it discusses the policies and policy makers that are guiding the future of CR.