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Large antenna arrays at the base station can facilitate power efficient single user downlink communication due to the inherent array power gain, i.e., under an average only total transmit power constraint, for a fixed desired information rate, the required total transmit power can be reduced by increasing the number of base station antennas (e.g. with i.i.d. fading, the required total transmit power...
In this paper, we study the multicast capacity of wireless ad hoc networks with infrastructure support. The network under study is termed as hybrid wireless network, where L-Maximum-Hop resource allocation strategy is adopted. There are n uniformly deployed normal wireless nodes and m regularly placed base stations dividing the network region into m cells. We show that the maximum capacity O(n1/2/k...
This paper envisions a near future in which the proliferation of wireless ad hoc networks in urban centers causes excessive spectrum pollution on currently allocated unlicensed bands. One solution for this problem is for the operators to lease freshly released spectrum from the regulators and sublease it to agencies in major cities. We consider one such operator who divides an urban area into regions...
Autonomous mobile robots, such as unmanned aerial or ground vehicles, will play important roles in future military and commercial applications. Future systems will require the robots to communicate with each other on a peer-to-peer basis over a wireless link and are able to form a networked system such as an ad hoc network. In this paper, we consider a problem of optimizing the topology of the network...
Context awareness, namely the provisioning of the current execution context at the application level, forces the continuous delivery of context data to resource-constrained mobile devices, and that can become too severe a constraint even for modern support (Android, iOS, etc.). This article focuses on the realization of a context data distribution infrastructure for Android-based mobile phones, and...
This study proposes an analytic localization algorithm by utilizing radical centers. Assume that a target node (blind node) can measure its distances to three or more anchor nodes (reference nodes). By picking three distance measurements to three anchor nodes, a radical center is computed. Through analytic formulation, the radical center is shown to be able to be treated as an estimation of the target...
As the most competitive and cost-efficient localization technology, the map-aided fingerprinting-assisted positioning has drawn a large body of attentions during the past decade. There are normally two phases, the off-line and on-line phases, and the construction of radio map in the off-line phase will significantly influence the location accuracy in the on-line phase. However, the radio map which...
Vehicular ad hoc networks (VANETs) have attracted much attention over the last few years. Localization and position information of vehicles is very significant in VANETs; this is a result of the special nature of VANETs. In this paper, we propose a location verification approach to prevent position-spoofing attacks on VANETs. Cooperative Location Verification (CLV), which is our approach, basically...
A major driver of healthcare cost is the inefficiencies associated keeping less-critical patients overnight in the hospital when these patients could be treated as outpatients and received comparable quality of care. To this end, we propose the concept of tether-free patient to support patient mobility and ensure privacy-preserving healthcare. The paper addresses issues related to the design of a...
Passive source localization has been the focus of considerable research efforts due to its usefulness in various applications. This paper performs a fundamental investigation of whether the gain ratios of arrival (GROAs) can be utilized in conjunction with the time differences of arrival (TDOAs) to improve the multiple sources localization accuracy with erroneous sensor positions. It's an urgent need...
A lot of works have been dedicated towards understanding the relationship between throughput capacity and packet delay in mobile ad hoc networks (MANETs). However, nearly all these works either assume a localized transmission range, or report the relationship between throughput capacity and packet delay only in terms of the number of users. It remains largely unknown for such a fundamental relationship...
In a disruption/delay tolerant network, message carriers are often used to act as relays between segregated nodes and gateways. In this paper, we study a special routing problem for message carriers in delay tolerant networks, the visiting frequency problem. Specifically, we present a detailed analysis on a near-optimal visiting frequency on the nodes in a subregion of the network, to ensure low average...
Delay/Disruption Tolerant Network (DTN) differs from the conventional networks in that it has no continuous or contemporaneous connections among wireless nodes. Its inherent characteristic of intermittent connections makes existing routing solutions hardly to be applied directly. Epidemic routing using random linear network coding has been studied and proved as an efficient way for delivering small...
Delay/disruption tolerant networking (DTN) offers a new solution to highly stressed communications in space environments. It is considered one of the most suitable technologies to be employed in space internetworking. To date, little work has been done in investigating how to achieve the best performance of DTN transmission over lossy, long-delay space channels. In this paper, we present an experimental...
Delay tolerant networks (DTNs) use mobility-assisted routing, where nodes carry, store, and forward data to each other in order to overcome the intermittent connectivity and limited network capacity of this type of network. In this paper, we propose a routing protocol that includes two mechanisms: message replication and message migration. Each mechanism has two steps: message selection and node selection...
How much information can one transmit over a randomly distributed ad hoc network of n secondary devices, overlaid with m primary devices? Such a network model is referred to as cognitive wireless network (CWN) and our paper addresses the above question by characterizing its throughput capacity. Although a handful of research efforts related to throughput capacity exist in the area of CWNs, most of...
The fc-connectivity of cognitive radio networks is discussed in this paper. By combining asymptotic k-connectivity and percolation, we define that the cognitive radio networks are k-connected if there exists an infinite k-connected component in the secondary network. Utilizing continuum percolation theory, we prove that the secondary network is k-disconnected if secondary users' density λ < log...
Collaborative spectrum sensing has been proposed recently to improve the sensing performance in Cognitive Radio networks. However, cooperative sensing will also introduce extra cost to the collaborator, such as the cooperative time and energy consumption. In reality, whether the rational secondary users have incentive to join the collaboration depends upon whether the benefit of the collaboration...
Spectrum sharing is an important topic in cognitive radio ad hoc networks (CRAHNs) and cognitive radio sensor networks (CRSNs). Bio-inspired consensus-based protocols can provide light-weight and efficient solutions for CRAHNs and CRSNs but the theoretical ground should be investigated for spectrum sharing fairness. In this paper, we investigate the convergence condition when applying a consensus...
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