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This work proposes CAC-RD: a call admission control for UMTS (universal mobile terrestrial system) networks. Its main challenge is to guaranty the maximum access/network availability while maintaining satisfactory performance levels. It is based on two schemes: channel reservation and network diagnosis. It reserves dynamically some channels to handovers, based on the network behavior. The diagnosis...
Owing to the limited requirement for sensor processing in early networked sensor nodes, embedded software was generally built around the communication stack. Modern sensor nodes have evolved to contain significant on-board functionality in addition to communications, including sensor processing, energy management, actuation and locationing. The embedded software for this functionality, however, is...
In recent years, we have seen tremendous growth in the applications of wireless sensor networks (WSNs) operating in unlicensed spectrum bands. However, there is evidence that existing unlicensed spectrum is becoming overcrowded. On the other hand, with recent advances in cognitive radio (CR) technology, it is possible to apply the dynamic spectrum access (DSA) model in WSNs to get access to less congested...
We present DESALalpha, a realization of the dynamic embedded sensor-actuator language for Telos-based devices. The platform provides native support for: (i) rule-based programming; (ii) synchronized action scheduling; (iii) neighborhood management; and (iv) distributed state sharing. We describe the design and implementation of DESALalpha, present examples that illustrate its use, and summarize the...
Developing routing protocol for vehicular ad hoc networks (VANET) is a challenging task due to potentially large network sizes, rapidly changing topology and frequent network disconnections, which can cause failure or inefficiency in traditional ad hoc routing protocols. We propose an adaptive connectivity aware routing (ACAR) protocol that addresses these problems by adaptively selecting an optimal...
The current access point (AP) association schemes in wireless LANs, such as IEEE 802.11, cause an unbalanced load which reduces the performance of both the entire network and individual users. Intensive studies were motivated to determine efficient methods of balancing loads among APs. Previous works provided either the heuristics without theoretical analysis on the performance, or algorithms that...
A rule-based intrusion detection system compares the incoming packets against rule set in order to detect intrusion. Unfortunately, it spends the majority of CPU time in packet classification to search for rules that match each packet. A common approach is to build a graph such as rule trees or finite automata for a given rule set, and traverse it using a packet as an input string. Because of the...
The Internet includes thousands of Internet service providers (ISPs) which are interconnected to provide connectivity and service for end-users. Traditionally, the settlement between the ISPs are determined based on bilateral agreements that result from pair-wise negotiations. Although this settlement mechanism is intuitive and easy to implement, it does not encourage network- wide cooperation, as...
The modeling of energy components in wireless sensor network (WSN) simulation is important for obtaining realistic lifetime predictions and ensuring the faithful operation of energy-aware algorithms. The use of supercapacitors as energy stores on WSN nodes is increasing, but their behavior differs from that of batteries. This paper proposes a model for a supercapacitor energy store based upon experimental...
Centrality is a concept often used in social network analysis to study different properties of networks that are modeled as graphs. We present a new centrality metric called localized bridging centrality (LBC). LBC is based on the bridging centrality (BC) metric that Hwang et al. recently introduced. Bridging nodes are nodes that are strategically located in between highly connected regions. LBC is...
We propose ORCHESTRA, a channel access protocol that uses reservations and virtual MIMO to provide high throughput and bounded channel access delays. Channel access process is divided into a contention-based access period and a scheduled access period. To attain high throughput, nodes build the channel schedule using the contention-based access period, and utilize the spatial multiplexing gain of...
We show that the fundamental problems in providing quality-of-service in the existing Internet architecture has been the assumption that a single, "best" path from source to destination is adequate for any communications requirements of the network. We present a new, best-effort architecture for providing quality-of-service in the Internet based on the use of the "best set of paths"...
In a semantic routed network (SRN), messages are routed based on the meaning of the message key. This means network nodes can be addressed by the meaning of the data content. Providing fast and successful semantic routing for any key is a challenging task due to conflicting performance demands. We present semantic routing table optimizing techniques to realize small world topology for fast and successful...
The problem of designing high capacity and high bit rate IP-over-WDM networks, which can provide uninterrupted service in the presence of network equipment failures, continues to attract significant interest from the research community. An IP-over-WDM network implements Internet Protocol (IP) directly over physical WDM network by establishing lightpaths using IP routers, optical crossconnects (OXC)...
This paper presents a framework of wireless multi-hop networks exploiting an ad hoc routing protocol working on the layer 2.5, called REAL (reputation based approach on 2.5-Layer) routing protocol. The framework of REAL routing protocol incorporates following three things: a new concept of wireless multi-hop network architecture, a new 2.5-layer routing technique with a reputation management scheme,...
Observing that simplicity implies efficiency and scalability, this paper proposes a position-based deployment and routing strategy, and then gives a concrete approach under this strategy, for the emerging wireless mesh networks with multiple radios and directional antennas. The main idea of this strategy is to deploy the mesh network in certain kind of geometric graph and then design a position-based...
Fault tolerant topology control in wireless networks has been studied recently. In order to achieve both sparseness (i.e., the number of links is linear with the number of nodes) and fault tolerance (i.e., can survive certain level of node/link failures), different geometric topologies were proposed and used as the underlying network topologies for wireless networks. However, most of the existing...
As the sale of digital content is moving more and more online, the content providers are beginning to realize that bandwidth infrastructures are not easily scalable. The emergence of peer-to-peer content delivery networks present these providers with a way to overcome this limitation. However, such networks have so far been ad-hoc in nature. One of the main reason for this has been the lack of incentives...
Portable video communication devices operate on batteries with limited energy supply. However, video compression is computationally intensive and energy-demanding. Therefore, one of the central challenging issues in portable video communication system design is to minimize the energy consumption of video encoding so as to prolong the operational lifetime of portable video devices. In this work, we...
Corruption of photopleythsmograms by motion artifacts has been a serious obstacle to the reliable use of pulse oximeters for real-time, continuous state-of-health monitoring. In this work, we propose a motion artifact reduction methodology that is effective even in the case of severe subject movement. The methodology involves an enhanced preprocessing unit consisting of a motion detection unit (MDU),...
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