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One of the fundamental differences between the terrestrial radio frequency (RF) signal and underwater acoustic signal is long propagation delay. This paper is focused on a scheduling scheme for regional data collection in underwater acoustic sensor networks. Long propagation delay of the acoustic signal causes a serious problem for transmission scheduling. In this paper, we propose an efficient transmission...
Dynamic spectrum access can enable secondary network users to access unused spectrum, or whitespace, which is found between the transmissions of primary users in a wireless network. The main design objectives for secondary user access strategy are to be able to ??scavenge?? spatio-temporally fragmented whitespace opportunities while limiting the amount of interference caused to the primary users....
The FlexNet-Waveform (FN-WF) is a new, highly-configurable MANET waveform for the international ground-based SDR arena, designed for the new FlexNet-One and FlexNet-Four hardware platforms. To ensure maximum compatibility and interoperability, the FN-WF assumes an IP-based platform with standard COTS protocols on the wired, Ethernet connections, while the wireless links utilize the best practices...
Modern Unmanned Aerial Vehicles (UAVs) have the capability of carrying sensors that produce large amounts of data. A high speed wireless data link is required to transfer this data to other systems for processing. This paper presents an FPGA-based implementation of a high data-rate (350 Mbps) QPSK modulator and demodulator to support a high data rate relay from a UAV to a ground station. By using...
This paper presents an analysis of satellite communications (SATCOM) systems that use Internet protocol (IP) with quality of service (QoS) metrics, and addresses IP efficiency measures. Key contributing elements for the IP efficiency are network structure, provisional efficiency, and bandwidth-on-demand features. IP bandwidth gains will also depend on the network size, the level of hierarchy, and...
Technology advancement has allowed submarines to evade standard sonar detection. A viable alternative is to place magnetic or acoustic sensors in close proximity to possible underwater pathways of submarines. This approach may require deploying large-scale underwater sensor networks to form 3-dimensional barriers. We devise an energy-conserving scheme to construct 3-dimensional barriers using mobile...
Bluetooth is one of the most widely available wireless technologies with over 2 billion Bluetooth-enabled devices shipped. Used by cell phones, laptops, gaming consoles and many other devices, it is the predominant wireless personal area networking technology. Over the last couple of years, US Government Departments including the Department of Defense (DoD) have begun to embrace Bluetooth due to its...
Daily sensor data volumes are increasing from gigabytes to multiple terabytes. The manpower and resources needed to analyze the increasing amount of data are not growing at the same rate. Current volumes of diverse data, both live streaming and historical, are not fully analyzed. Analysts are left mostly to analyzing the individual data sources manually. This is both time consuming and mentally exhausting...
Communications systems are increasingly reliant on system-on-chip (SoC) solutions. As the complexity and size of SoCs continues to grow, so does the risk of ??Trojan?? attacks, in which an integrated circuit (IC) design is surreptitiously and maliciously altered at some point during the design or manufacturing process. Despite the risks that such an attack entail, relatively little attention has been...
The foray of wireless sensor networks into time-sensitive applications demands support for emergency services with guaranteed quality of service (QoS) bounds. We introduced CP-EDCA, a channel preemptive enhancement to the IEEE 802.11e EDCA standard, for guaranteed emergency medium access in distributed wireless environments. The performance results for emergency traffic depicted 50% uniform decrease...
This paper discusses the database structure of an RF taxonomy modeling tool being developed on a Missile Defense Agency (MDA), Phase II, Small Business Innovative Research (SBIR) augmentation contract. The tool is called the communications system taxonomy (CommTax) toolkit. The data model underlying the Commtax toolkit will be available to other users as a framework for the transfer of data to other...
A proper situation management system is one of the keys to success on the battlefield. It strongly relies on data collection, fusion and interpretation. Unmanned Aerial Vehicles (UAVs) are becoming a major collection platform, but there is almost no collaborative intelligence in these systems. We claim that a swarm of small UAVs connected together that could make cooperative decisions in an autonomous...
OFDM offers high bandwidth efficiency and low receiver equalization complexity; consequently OFDM is growing in popularity for adoption into robust high data rate services in wireless multipath channels. While these advantages have been proven for many wireless applications (including numerous IEEE wireless standards), one potential disadvantage of OFDM is that it exhibits high peak-to-average power...
We consider a physical layer security based on the wiretap channel for wireless communication systems in which there are one transmitter and multiple receivers/users who report their channel state information (CSI) to the transmitter. This scenario is practically useful since it models the forward link of cellular systems where the systems can take advantage of the multiuser diversity. We are curious...
To support highly flexible network mobility in mobile communication systems, various types of movable network entities, especially mobile base stations (M-BSs), will appear in near future. In this environment, a scanning process to identify the availability of neighbor M-BSs for handoff should be newly designed, because a conventional method does not reflect the motion of base stations. Therefore,...
Frequency hopping provides some protection against multiple access interference in random-access ad hoc networks. Power control and the use of short routing hops can further reduce interference by promoting spatial reuse. If the network is fully connected, frequency hopping and power control alone may be sufficient to allow good throughput without the use of routing. This approach is particularly...
We introduce complete analytical characterization of the nonlinear interference that results when passing more than one high-order modulation carrier through the same nonlinear transponder HPA. Based on this analysis, a novel Volterra filter is proposed that models nonlinear intersymbol interference (ISI) and adjacent channel interference (ACI). Our focus is on adaptive algorithms so that the solutions...
Limited capabilities and mission requirements imply that nodes in tactical mobile ad-hoc networks (MANETs) carry a significant risk of being compromised physically or logically. In addition nodes or groups of nodes may defect, which is a particular concern in coalition environments where networks may spread beyond organizational boundaries. To identify defecting or compromised nodes including Byzantine...
The army is increasingly reliant on beyond line of sight (BLOS) communications due to a non-contiguous battlefield. The war fighter also requires mobility and network connectivity to provide the needed level of near real-time, tactically-relevant information. On-the-move (OTM) space based communications forms a critical layer in supporting these essential networking capabilities. There are a significant...
We present a systematic network coding strategy for cooperative communication, in which some nodes may replicate-and-forward packets in addition to sending random linear combinations of the packets. We argue that if this strategy is used only at certain nodes in the network, the throughput will not be reduced relative to random linear network coding. Furthermore, if packets can traverse the entire...
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