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Richard Wolff

Montana State University - Bozeman, Engineering, Faculty Member

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Address: Bozeman, Montana, United States

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Papers by Richard Wolff

Search for X-Ray Polarization in Sco X-1

Physical Review Letters, 1969

An x-ray polarimeter sensitive to x rays in the energy range from 6 to 18 keV, flown above the at... more An x-ray polarimeter sensitive to x rays in the energy range from 6 to 18 keV, flown above the atmosphere on 27 July 1968, was used both to set an upper limit on the polarization of Sco X-1 and to check for spurious indications of polarization which might result from the anisotropy of the cosmic rays. %'ithin the statistical limitations of the data, no evidence was found for spurious background polarization. A Thomson-scattering x-ray polarimeter sensitive in the spectral range of about 6 to 18 keV was flown from the White Sands Missle Range at 0356 UT on 27 July 1968 in an Aerobee-150 sounding rocket. Initially the instrument was

Simple and effective routing and wavelength assignment in transparent optical networks

2012 IEEE International Conference on Communications (ICC), 2012

ABSTRACT Transparent optical networks must support dynamic traffic demands and end-to-end optical... more ABSTRACT Transparent optical networks must support dynamic traffic demands and end-to-end optical transmission. We present a new physically-aware algorithm based on dynamic programming for routing and wavelength assignment in such networks that considers both linear and nonlinear impairments that accumulated along the transmission path. We show that our algorithm scales well to large networks and typically yields the lowest blocking probability when compared to several existing methods. In addition, it is flexible and can adapt to situations where either linear or nonlinear impairments dominate.

Upper Limit of the X-ray Polarization of the Crab Nebula

The Crab Nebula, 1971

A rocket-borne X-ray polarimeter was flown to search for polarization in Taurus X-l. Although a r... more A rocket-borne X-ray polarimeter was flown to search for polarization in Taurus X-l. Although a result consistent with zero polarization was obtained, the statistics were such that X-ray polarization comparable in magnitude and direction to that of radio and optical continuum emission cannot be excluded.

A Large Area Thomson-Scattering Stellar X-Ray Polarimeter

Symposium - International Astronomical Union, 1971

An instrument for measuring the polarization of stellar X-ray emission has been designed, constru... more An instrument for measuring the polarization of stellar X-ray emission has been designed, constructed, and tested. The polarization dependence of incoherent Thomson scattering in lithium metal is utilized. Means for suppression of cosmic ray background effects have been provided. The apparatus has been flown in rockets to obtain data in the polarization of X-ray sources in Sco X-1 and Tau X-1.

Beam scheduling and relay assignment in wireless relay networks with smart antennas

2013 Proceedings IEEE INFOCOM, 2013

Relay Stations (RSs) can be deployed in a wireless network to extend its coverage and improve its... more Relay Stations (RSs) can be deployed in a wireless network to extend its coverage and improve its capacity. Smart (directional) antennas can enhance the functionalities of RSs by forming the beam only towards intended receiving Subscriber Stations (SSs). In this paper, we study a joint problem of selecting a beam width and direction for the smart antenna at each RS and determining the RS assignment for SSs in each scheduling period. The objective is to maximize a utility function that can lead to a stable and high-throughput system. We define this as the Beam Scheduling and Relay Assignment Problem (BS-RAP). We show that BS-RAP is NP-hard, present a Mixed Integer Linear Programming (MILP) formulation to provide optimal solutions and present two polynomial-time greedy algorithms, one of which is shown to have a constant factor approximation ratio.

Mobile computing and communications (abstract)

Proceedings of the 22nd annual ACM computer science conference on Scaling up : meeting the challenge of complexity in real-world computing applications meeting the challenge of complexity in real-world computing applications - CSC '94, 1994

OSO-8 X-Ray Polarimeter and Bragg Crystal Spectrometer Observations

Highlights of Astronomy, 1977

The OSO-8 satellite contains a focusing mosaic graphite crystal X-ray polarimeter that is oriente... more The OSO-8 satellite contains a focusing mosaic graphite crystal X-ray polarimeter that is oriented along the spin axis of the wheel section of the satellite. The polarimeter operates at 2.6 and 5.2 keV. Polarization in a source appears as a modulation of the counting rate at twice the satellite spin frequency. The amplitude and phase of the modulation are simply related to the polarization and position angle, respectively. Two independent polarimeters are employed, and their axes are offset by 128°. Focusing is achieved by mounting the crystals on a parabolic sector, which reduces the background without reducing the sensitivity. The low background that results from the focusing not only improves the statistical quality of the data but also substantially reduces the danger that an asymmetry in the charged particle background may produce a spurious polarization result. This is particularly important in the case of weak sources. The instrument has been described in detail elsewhere (No...

A Hardware Based Ricean Fading Radio Channel Simulator

Wireless Personal Communications, 2014

In presenting this thesis in partial fulfillment of the requirements for a master's degree at Mon... more

The X-ray line and continuum emission from a solar active region

Solar Physics, 1975

Citizen Political Enfranchisement and Information Access: Telecommunications Services in Rural and Remote Areas

A Wireless Computer Games and Video Entertainment System for the Aircraft Cabin Environment

Current aircraft cabin systems utilize a wired network topology and offer only limited passenger ... more Current aircraft cabin systems utilize a wired network topology and offer only limited passenger entertainment services. In this paper we explore the feasibility of utilizing a wireless network to reduce cabin wiring and reconfiguration costs and to provide passengers with a high-quality entertainment experience including personalized video and audio as well as state-of-the-art computer games. The problem addressed is to determine whether this is feasible given the computer system demands of today’s state-of-the-art network based games combined with the design constraints imposed by the aircraft cabin environment and the bandwidth demands of streaming video. In both cases, the study assumes functionality that would be commercially available in the 2008 timeframe and beyond. We develop several architectures and through a combination of emulation and simulation, assess the viability of each alternative. We show that a highly distributed architecture, utilizing trends in mobile gaming ...

A Wireless Computer Games and Video Entertainment System for the Aircraft Cabin Environment

Current aircraft cabin systems utilize a wired network topology and offer only limited passenger ... more Current aircraft cabin systems utilize a wired network topology and offer only limited passenger entertainment services. In this paper we explore the feasibility of utilizing a wireless network to reduce cabin wiring and reconfiguration costs and to provide passengers with a high-quality entertainment experience including personalized video and audio as well as state-of-the-art computer games. The problem addressed is to determine whether this is feasible given the computer system demands of today’s state-of-the-art network based games combined with the design constraints imposed by the aircraft cabin environment and the bandwidth demands of streaming video. In both cases, the study assumes functionality that would be commercially available in the 2008 timeframe and beyond. We develop several architectures and through a combination of emulation and simulation, assess the viability of each alternative. We show that a highly distributed architecture, utilizing trends in mobile gaming ...

Transient Effects in MEMS-switched All-Optical Networks with EDFAs

We explore and report on the temporal behavior of MEMS-based optical switching elements and optic... more We explore and report on the temporal behavior of MEMS-based optical switching elements and optical amplifiers in multiwavelength systems as may be utilized in next generation optical networks. The importance of this work is underscored by the growing use of dense wavelength division multiplexing (DWDM) in conjunction with dynamically controlled optically transparent network elements. Switching, using MEMS technology, has taken on an important role in supporting dynamic network reconfiguration. Such networks typically include optical amplifiers, and multiple wavelengths are amplified by a single network element The combination of MEMS switching with optical amplifiers and other active elements provides new challenges in overall system design, as the millisecond switching time of MEMS fabrics is comparable to the excited state lifetime in Erbium doped fiber amplifiers (EDFAs), thereby leading to potentially undesirable gain fluctuations and cross talk. Our observations of such transi...

A Terrain based Routing Protocol for Sparse Ad-Hoc Intermittent Networking (TRAIN)

We propose and investigate a new approach of terrain and location based routing (TRAIN) designed ... more We propose and investigate a new approach of terrain and location based routing (TRAIN) designed to improve performance for sparse ad hoc networks where relatively large node separations and terrain blockage can result in periods of intermittent connectivity. Building on DSR, we developed a procedure where a mobile node, through use of terrain and location data, can determine whether there is line of sight (LOS) to another node. Knowledge of trajectories is combined with terrain information to forecast link conditions. Performance assessment was conducted by simulation using OPNET Modeler TM 10.5. Our results show that TRAIN can improve throughput relative to unmodified DSR by as much as a factor of two when path blockage occurs.

EDFA transient reduction using power shaping

Many erbium doped fiber amplifier (EDFA) based multiwavelength optical networks employ techniques... more Many erbium doped fiber amplifier (EDFA) based multiwavelength optical networks employ techniques such as burst-switching or packet switching where the time interval between traffic blocks can be long enough to induce EDFA optical power transients. The optical power transients are created by abrupt changes in the average input power to the EDFAs and can adversely affect the performance of the network. To mitigate the effects of EDFA optical power transients on optical networks, a method based on power shaping where heads and tails are joined to the beginning and end of a traffic block is proposed. A head (tail) gradually increases (decreases) the channel power by employing a pseudo-random bit sequence in which the probability of a “1” (“0”) increases from 0 to 0.5. Theoretical and experimental results both show that EDFA optical power transients can be significantly reduced with adequate shaping periods. For a linear shaping profile, drop transient deviation was reduced by .5dB whil...

A Border Node Based Routing Protocol for Partially Connected Vehicular Ad Hoc Networks

Journal of Communications, 2010

Research on vehicular ad hoc networks (VANETs) has focused primarily on efficient routing protoco... more Research on vehicular ad hoc networks (VANETs) has focused primarily on efficient routing protocol design under conditions where there are relatively large numbers of closely spaced vehicles, typical of major highways and urban areas. These routing protocols are designed principally for fully connected networks and are not suitable for packet delivery in a sparse, partially connected VANET. In rural areas, vehicle densities are low and roadway communication infrastructure is scarce, leading to long periods where vehicle-to-vehicle or vehicleto-roadside communications is infrequent, interrupted, or simply not possible. These attributes characterize a sparse VANET, and are characteristic of delay tolerant networks (DTNs). In this paper, we examine the challenges of VANETs in sparse network conditions, review alternatives including epidemic routing and propose a Border node Based Routing (BBR) protocol for partially connected VANETs. Unlike many VANET protocols that assume location awareness or mobility patterns to aid in routing decisions, BBR is designed to function in domains where location and mobility information is not available, as is typical in rugged terrain conditions. The BBR protocol can tolerate network partition due to low node density and high node mobility. The performance of this protocol is evaluated in OPNET TM with a Random Waypoint mobility model and a Geographic and Traffic Information (GTI) based mobility model that captures typical highway conditions. The simulation results are compared with those obtained using the Dynamic Source Routing (DSR) protocol and with an epidemic routing protocol. The simulation results show that BBR performs well for partially connected VANETs where other protocols fail and provides the advantage of not relying on a location service required by other protocols proposed for VANETs.

An estimate of network database transaction volume to support personal communications services

1st International Conference on Universal Personal Communications - ICUPC '92 Proceedings

Method and system for communication on optical fiber using mechanical modulation

Reliable Routing for Roadside to Vehicle Communications in Rural Areas

2008 IEEE International Conference on Communications, 2008

The demands for vehicular Internet access are proliferating. Access Points (APs) can be deployed ... more The demands for vehicular Internet access are proliferating. Access Points (APs) can be deployed along the roadside to provide wireless coverage and network access for mobile vehicles. However, high mobility may cause frequent link breakages, which will seriously impact Quality of Service (QoS). In this paper, we study reliable routing for Roadside to Vehicle (R2V) communications in rural areas where rough terrain poses additional challenges. We propose a novel routing protocol where the stationary APs play a key role in route maintenance. The protocol includes a prediction algorithm which can predict the lifetimes of wireless links with consideration for terrain effects, as well as routing algorithms which can find stable paths for packet forwarding based on the prediction. Simulation results based on OPNET Modeler and the rural roadways in the Yellowstone National Park show that the proposed protocol substantially outperforms existing ad-hoc routing protocols.

Measurement of the Polarization of the X-Ray Emission of the Crab Nebula

Thesis Columbia University 1970 Source American Doctoral Dissertations Source Code X1970 Page 0258, 1970