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Wireless mesh networks (WMNs) have emerged recently to extend Internet access and other networking services. WMNs routers provide network access to the clients and other networking functions such as routing, and packet forwarding. Bandwidth scarcity is the main challenge that limits the performance of WMNs. Although considerable research has been conducted on spectrum allocation, spectrum management...
Hierarchical architectures are more and more widely adopted for organizing wireless sensor networks. In such architectures, middle-tier nodes take important roles, and preventing a malicious node from impersonating a middle-tier node and injecting falsified messages becomes critical. In this paper, we propose an energy efficient, distributed scheme to secure the multicast messages from the middle-tier...
Wireless sensor networks consist of low-cost and low- power radio devices and are deployed in open and unprotected areas. Privacy is becoming one of the major issues that jeopardize the successful deployment of wireless sensor networks. While confidentiality of the message can be ensured through content encryption, it is much more difficult to adequately address the source-location privacy. For wireless...
We analyze routing algorithm for wireless sensor networks called power aware differentiated routing (PADR), which is proposed for collaborative routing of real-time (RT) and non-real time (NRT) traffic in a sensor field in order to prolong the otherwise shorter life time of RT sensor network. PADR uses nodes in the non-real time network as backup for routing RT traffic. It involves swapping a forwarding...
We validate a call admission control (CAC) method for mobile cellular networks under more restrictive conditions than those assumed in its design. The method uses distribution and the first and second moments of the channel holding time (CHT) parameter to compute the algorithm's main admission control metric: remaining CHT. Our goal is to generalize the handover method when only the mean and variance...
Communication between a transmitter and a receiver using electromagnetic waves does not scale to nano-sizes. To enable communication between nano-sized devices separated by a short distance, molecular communication has recently been proposed as a feasible scheme. The transmitter disperses molecules into the medium, which propagate to, and are sensed by, the receiver. In this paper, we wish to mathematically...
In this research, we propose a robust Sybil attack detection framework for MANETs based on cooperative monitoring of network activities. We do not require designated and honest monitors to perform the Sybil attack detection. Each mobile node in the network observes packets passing through it and periodically exchanges its observations in order to determine the presence of an attack. Malicious nodes...
The idea of identifying and removing repetitive patterns in the raw network data transmissions, also known as protocol-independent redundancy elimination, has received thorough consideration in the academic community and also was integrated into several commercial appliances. The original intention of the redundancy elimination was to increase the capacity of low bandwidth network connections, utilizing...
To minimize the number of wavelengths required by a multicast session in sparse light splitting wavelength division multiplexing (WDM) networks, a light-hierarchy structure, which occupies the same wavelength on all links, is proposed to span as many destinations as possible. Different from a light-tree, a light-hierarchy accepts cycles, which are used to traverse crosswise a 4-degree (or above) multicast...
Joint channel-aware and queue-aware scheduling has been studied widely for direct downlink transmission in cellular networks. In this paper, we combine this cross-layer scheduling concept with opportunistic relaying for slotted multiuser packet transmissions. Cooperative relaying can bring additional degree of freedom, resulting in the system performance improvement in terms of throughput and fairness...
Automated geolocation of IP addresses has important applications to targeted delivery of local news, advertising and other content over the Internet. Previous measurement-based approaches to geolocation employ active probing to measure delays among a set of landmark nodes with known locations. The location of a target IP address can be approximated by that of the nearest landmark, as determined by...
This paper presents an adaptive MAC (AMAC) protocol for supporting MAC layer adaptation in cognitive radio networks. MAC protocol adaptation is motivated by the flexibility of emerging software-defined radios which make it feasible to dynamically adjust radio protocols and parameters. Dynamic changes to the MAC layer may be useful in wireless networking scenarios such as tactical or vehicular communications...
The Internet was designed as a packet-switched network in the 1960's and 1970's, with the explicit intent of sacrificing quality-of-service guarantees for an individual application in order to optimize channel usage and provide optimal median service for all applications. This approach was successful, since the application mix of the Internet heretofore has been dominated by applications with low...
There have been extensive studies on RFID security, in particular authentication and privacy issues. In most protocols, the discussions focus on scenarios that RFID tags are used mainly for tracing or identification, and the access to data stored on RFID is enforced through authentication. Recently, there rise interests of using RFID tags as distributed storage, e.g., storing floorplans which can...
Popular Internet applications deploy a multi-tier architecture, with each tier provisioning a certain functionality to its preceding tier. The session-based admission control approach (SBAC) designed for a single Web server is not effective for a multi-tier architecture. This is due to the fact that the bottleneck in a multi-tier Website dynamically shifts among tiers as client access patterns change...
In this paper, we propose contention resolution algorithms for multi-packet reception slotted ALOHA systems with immediate- and delayed-first-transmission protocols, in which a base station broadcasts the retransmission probability for each slot to all mobile terminals. As a cross-layer approach, the base station estimates the system backlog by exploiting information on multiple access interference...
In this paper, we propose two novel data fusion schemes for cooperative spectrum sensing in the IEEE 802.22 WRAN system. The data fusion structure is proper for the WRAN system due to its centralized structure, and it can provide reliable sensing performance. The proposed data fusion schemes improve the sensing reliability by utilizing confidence vector of the sensing result. Moreover, application...
Particle filters have been successfully employed to track multiple-input multiple-output (MIMO) fiat fading channels for mobile wireless communications. However, an optimal importance density cannot be always found to optimize the performance of a particle filter. A suboptimal importance density such as the prior can be used; but it has a problem of ignoring the current observations. In addition,...
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