779 research outputs found
Analysis of Ultra Wide Band (UWB) Technology for an Indoor Geolocation and Physiological Monitoring System
The goal of this research is to analyze the utility of UWB for indoor geolocation and to evaluate a prototype system, which will send information detailing a person’s position and physiological status to a command center. In a real world environment, geolocation and physiological status information needs to be sent to a command and control center that may be located several miles away from the operational environment. This research analyzes and characterizes the UWB signal in the various operational environments associated with indoor geolocation. Additionally, typical usage scenarios for the interaction between UWB and other devices are also tested and evaluated
Interference Networks with Point-to-Point Codes
The paper establishes the capacity region of the Gaussian interference
channel with many transmitter-receiver pairs constrained to use point-to-point
codes. The capacity region is shown to be strictly larger in general than the
achievable rate regions when treating interference as noise, using successive
interference cancellation decoding, and using joint decoding. The gains in
coverage and achievable rate using the optimal decoder are analyzed in terms of
ensemble averages using stochastic geometry. In a spatial network where the
nodes are distributed according to a Poisson point process and the channel path
loss exponent is , it is shown that the density of users that can be
supported by treating interference as noise can scale no faster than
as the bandwidth grows, while the density of users can scale
linearly with under optimal decoding
Cognitive Communications and Networking Technology Infusion Study Report
As the envisioned next-generation SCaN Network transitions into an end-to-end system of systems with new enabling capabilities, it is anticipated that the introduction of machine learning, artificial intelligence, and other cognitive strategies into the network infrastructure will result in increased mission science return, improved resource efficiencies, and increased autonomy and reliability. This enhanced set of cognitive capabilities will be implemented via a space cloud concept to achieve a service-oriented architecture with distributed cognition, de-centralized routing, and shared, on-orbit data processing. The enabling cognitive communications and networking capabilities that may facilitate the desired network enhancements are identified in this document, and the associated enablers of these capabilities, such as technologies and standards, are described in detail
DiffServ resource management in IP-based radio access networks
The increasing popularity of the Internet, the flexibility of IP, and the wide deployment of IP technologies, as well as the growth of mobile communications have driven the development of IP-based solutions for wireless networking. The introduction of IP-based transport in Radio Access Networks (RANs) is one of these networking solutions. When compared to traditional IP networks, an IP-based RAN has specific characteristics, due to which, for satisfactory transport functionality, it imposes strict requirements on resource management schemes. In this paper we present the Resource Management in DiffServ (RMD) framework, which extends the DiffServ architecture with new admission control and resource reservation concepts, such that the resource management requirements of an IP-based RAN are met. This framework aims at simplicity, low-cost, and easy implementation, along with good scaling properties. The RMD framework defines two architectural concepts: the Per Hop Reservation (PHR) and the Per Domain Reservation (PDR). As part of the RMD framework a new protocol, the RMD On DemAnd (RODA) Per Hop Reservation (PHR) protocol will be introduced. A key characteristic of the RODA PHR is that it maintains only a single reservation state per PHB in the interior routers of a DiffServ domain, regardless of the number of flows passing through
Spectrum Sharing in Dynamic Spectrum Access Networks: WPE-II Written Report
A study by Federal Communication Commission shows that most of the spectrum in current wireless networks is unused most of the time, while some spectrum is heavily used. Recently dynamic spectrum access (DSA) has been proposed to solve this spectrum inefficiency problem, by allowing users to opportunistically access to unused spectrum. One important question in DSA is how to efficiently share spectrum among users so that spectrum utilization can be increased and wireless interference can be reduced. Spectrum sharing can be formalized as a graph coloring problem. In this report we focus on surveying spectrum sharing techniques in DSA networks and present four representative techniques in different taxonomy domains, including centralized, distributed with/without common control channel, and a real case study of DSA networks --- DARPA neXt Gen- eration (XG) radios. Their strengths and limitations are evaluated and compared in detail. Finally, we discuss the challenges in current spectrum sharing research and possible future directions
Assessment of Cognitive Communications Interest Areas for NASA Needs and Benefits
This effort provides a survey and assessment of various cognitive communications interest areas, including node-to-node link optimization, intelligent routing/networking, and learning algorithms, and is conducted primarily from the perspective of NASA space communications needs and benefits. Areas of consideration include optimization methods, learning algorithms, and candidate implementations/technologies. Assessments of current research efforts are provided with mention of areas for further investment. Other considerations, such as antenna technologies and cognitive radio platforms, are briefly provided as well
Software Defined Radio Implementation of Carrier and Timing Synchronization for Distributed Arrays
The communication range of wireless networks can be greatly improved by using
distributed beamforming from a set of independent radio nodes. One of the key
challenges in establishing a beamformed communication link from separate radios
is achieving carrier frequency and sample timing synchronization. This paper
describes an implementation that addresses both carrier frequency and sample
timing synchronization simultaneously using RF signaling between designated
master and slave nodes. By using a pilot signal transmitted by the master node,
each slave estimates and tracks the frequency and timing offset and digitally
compensates for them. A real-time implementation of the proposed system was
developed in GNU Radio and tested with Ettus USRP N210 software defined radios.
The measurements show that the distributed array can reach a residual frequency
error of 5 Hz and a residual timing offset of 1/16 the sample duration for 70
percent of the time. This performance enables distributed beamforming for range
extension applications.Comment: Submitted to 2019 IEEE Aerospace Conferenc
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