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In ad-hoc networks, routing is one of the most important issues, and various protocols are proposed. However, as situations and topologies of an ad-hoc network are various and dynamic, it is difficult for a single fixed protocol to perform well for all occasions. Therefore, some dynamic and adaptive mechanism in routing protocols is necessary. In this paper, we propose an adaptive routing system for ad-hoc networks. This system begins in the same manner as a reactive protocol, and when the network situation gets unsuitable for the protocol, the system changes its manner of routing with a router-node, or a pseudo cluster-head in Cluster-based Routing, which emerges autonomously at the place of “hot spots” in the network. This paper presents its principle, design, and some preliminary experiment results.

In P2P network, there are a considerable proportion of free riders, which contribute nothing or little to the P2P system but obtain resources from the system. In order to address this problem, we present a utility-based auction cooperation incentive mechanism in the P2P network. Our approach is that before communicating with destination peer, the source peer first demands peers to auction their utilities, and then select the maximum utility as its destination peer, and gives some benefit to it, at the same time, gives some punishment to the liars. By using this mechanism, the more the peers contribute to the system, the more utility the peers can obtain, and therefore, the more benefits the peers can gain from the system. The experiment results show that the incentive mechanism assures the justice of gaining benefits for different kinds of peers in the system, and hence, controls the free riders effectively, and improves the whole performance of the P2P network.

Mobile devices have difficulty in sustaining various services as in a wired environment, due to the storage shortage of the mobile device. The research[8] which provides remote storage service for mobile appliances using iSCSI has been conducted to overcome the storage shortage in mobile appliances. In research the proposed cache server performed well with relatively small files of sizes, however, did not perform well with large files such as database files, multimedia files, etc. The reason was the mobile device could not grasp the file as a whole and thus the cache server encountered frequent cache miss in spite of its huge buffer. In this paper we propose a proxy server that accommodates large files for mobile devices thus attains very high hit ratio.

We study the maximization of throughput and energy utilization in noisy wireless channels by adjusting packet length adaptively to network instant statistics. The optimal packet length adaptation (PLA) for throughput and energy utilization in wireless networks with and without re-transmission is respectively derived and developed. As more noises introducing more energy consumptions, the noises are equivalently regarded as lengthening of transmission distances. Therefore, an equivalent distance model of noisy channels is developed for more accurate estimation of the dissipated proportion in the residual energy such that further improvement of energy utilization and throughput is obtained. We integrate the PLA with the energy-proportional routing (EPR) algorithm for best balance of energy load. Therefore, performance metrics such as lifetime extension, throughput, and energy utilization are maximized even the distribution of channel noise is so un-predictable. Since the equivalent distance is dynamic, we believe that it is useful for network topology re-organization and will be useful in the future work of mobile ad-hoc networks.

In order to develop a variety of context-aware application systems, we require a context script language to describe both various decisions on context-awareness and appropriate procedures according to the decision. In this paper, we propose a new context script language which can represent a variety of contexts as a standard syntax. The proposed context script language is a general purpose one to provide users with functions to define a given context in a clear and precise manner. To show the usefulness of the proposed context script language, we develop a context-aware application system using it, which can provide users with a music playing service in ubiquitous computing environment.

Object replication is an important and sophisticated question, it can reduce access latency and bandwidth consumption, replication can also help in load balancing and can improve reliability by creating multiple replicas of the same storage object. But there are many difficulties to realize object replication in efficiently. In this paper, we discuss the architecture of object storage system with object replication, and analyze key question of dynamic replication such as replica granularity, When to replicate storage object and Where to place the replicas etc.. In the theory, we give the formulas of these question, the analysis prove these formulas are reasonable.

A mobile network is an entire network, moving as a unit, which dynamically change its point of attachment to the Internet and its reach-ability in the topology. Network Mobility is thus the opportunity to realize the Ubiquitous Internet, i.e. permanent access anywhere at anytime, in fixed locations and while on the move, provided that any available access network can be accommodated. In this paper, we propose a cost-effective mobility modelling in nested Network Mobility which is based on binding update multi-cast by various mobility patterns of mobile nodes in nested Network Mobility. This proposed scheme is combined Hierarchical Mobile IPv6 with Network Mobility because a mobile networks and mobile nodes move in tandem and create a hierarchy in the wireless network to management of micro-mobility and seamless handoff. These issues are focuses on the area of mobility modelling in nested Network Mobility. We address the key function for our proposed scheme and simulate the usefulness of our proposed method using mathematically analyze. We then testify that the proposal has best performance compared with Network Mobility protocol.

To free analysts from knowing about the internal details of middleware when evaluating the performance of component-based system (CBS), this paper proposes a framework to automatically integrate middleware component interactions and their performance attributes to application Unified Model Language (UML) model. The framework defines a general sub-model template library of middleware, a middleware usage description file, and an approach to compositing application-specific sub-model instances and application UML models. The process is illustrated by a case study.

In the IEEE 802.15.3-based HR-WPAN(High Rate Wireless Personal Area Networks), the selection of PNC is based on the capability of each DEV in the piconet. The selected DEV playing the role of a PNC will consume the most amount of energy among the DEVs in the piconet. Since the energy consumption of the PNC is closely related to its frame transmission range in the piconet, it is important to consider the relative location of each DEV when selecting the PNC among DEVs. In this paper, we propose a novel approach to the PNC selection procedure in the piconet that attempts to position the PNC at the center of the topology. By doing so, it can minimize the total transmission distances from the PNC to all other DEVs, resulting in saving energy for the PNC and therefore extending the life-time of the PNC as well as the piconet. We describe our method in detail and present experimental results that show the significant improvement in the energy saving.

In wireless ad hoc networks, many multicast routing protocols are proposed such as ODMRP, MAODV, etc. In general, the IEEE 802.11 standard is assumed as a MAC protocol in those protocol and multicast data packets are transmitted at the basic transmission rate which is 2Mbps at the IEEE 802.11 or 802.11b. However, if the multicast packet can be transmitted at higher transmission rates than 2Mbps in a multi-rate WLAN such as IEEE 802.11b, we can achieve higher throughput gain and lower transmission delay than those at 2Mbps transmission rate. In this paper, we propose a new multicast routing protocol in multi-rate wireless ad hoc networks. In the proposed protocol, we design a multicast mesh creation method considering multiple transmission rates between any two nodes in the ad hoc networks. We also design a multicast mesh maintenance scheme when the transmission rate between two nodes comprising a multicast mesh is changed because of node mobility. The performance of the proposed protocol is compared with ODMRP using ns2 simulation, and the proposed protocol shows higher packet delivery ratio and lower end-to-end delay than the ODMRP.