@article{asokan_ozdemir_guvenc_sichitiu_2024, title={Aerial RF and Throughput Measurements on a Non-Standalone 5G Wireless Network}, ISBN={["979-8-3503-1765-7"]}, ISSN={["2473-070X"]}, DOI={10.1109/DySPAN60163.2024.10632812}, journal={2024 IEEE INTERNATIONAL SYMPOSIUM ON DYNAMIC SPECTRUM ACCESS NETWORKS, DYSPAN 2024}, author={Asokan, Ram and Ozdemir, Ozgur and Guvenc, Ismail and Sichitiu, Mihail L.}, year={2024}, pages={120–123} }
 @article{maeng_raouf_guvenc_ozdemir_sichitiu_dutta_2024, title={Key Observations from Altitude-Dependent Sub-6 GHz Spectrum Measurements at AERPAW}, ISBN={["979-8-3503-1765-7"]}, ISSN={["2473-070X"]}, DOI={10.1109/DySPAN60163.2024.10632856}, journal={2024 IEEE INTERNATIONAL SYMPOSIUM ON DYNAMIC SPECTRUM ACCESS NETWORKS, DYSPAN 2024}, author={Maeng, Sung Joon and Raouf, Amir H. F. and Guvenc, Ismail and Ozdemir, Ozgur and Sichitiu, Mihail L. and Dutta, Rudra}, year={2024}, pages={135–138} }
 @article{maeng_ozdemir_guvenc_sichitiu_2024, title={Kriging-Based 3-D Spectrum Awareness for Radio Dynamic Zones Using Aerial Spectrum Sensors}, volume={24}, ISSN={["1558-1748"]}, url={https://doi.org/10.1109/JSEN.2024.3357430}, DOI={10.1109/JSEN.2024.3357430}, abstractNote={Radio dynamic zones (RDZs) are geographical areas within which dedicated spectrum resources are monitored and controlled to enable the development and testing of new spectrum technologies. Real-time spectrum awareness within an RDZ is critical for preventing interference with nearby incumbent users of the spectrum. In this article, we consider a 3-D RDZ scenario and propose to use unmanned aerial vehicles (UAVs) equipped with spectrum sensors to create and maintain a 3-D radio map of received signal power from different sources within the RDZ. In particular, we introduce a 3-D Kriging interpolation technique that uses realistic 3-D correlation models of the signal power extracted from extensive measurements carried out at the NSF Aerial Experimentation and Research Platform for Advanced Wireless (AERPAW) platform. Using ${C}$ -band signal measurements by a UAV at altitudes between 30 and 110 m, we first develop realistic propagation models on air-to-ground path loss, shadowing, spatial correlation, and semi-variogram, while taking into account the knowledge of antenna radiation patterns and ground reflection. Subsequently, we generate a 3-D radio map of a signal source within the RDZ using the Kriging interpolation and evaluate its sensitivity to the number of measurements used and their spatial distribution. Our results show that the proposed 3-D Kriging interpolation technique provides significantly better radio maps when compared with an approach that assumes perfect knowledge of path loss. Specifically, the root-mean-square error (RMSE) of the signal power prediction achieved by our proposed 3-D Kriging method is notably lower compared to that of the perfect path loss-based prediction, especially when the height difference between measured and the target locations is less than 20 m.}, number={6}, journal={IEEE SENSORS JOURNAL}, author={Maeng, Sung Joon and Ozdemir, Ozgur and Guvenc, Ismail and Sichitiu, Mihail L.}, year={2024}, month={Mar}, pages={9044–9058} }
 @article{maeng_ozdemir_guvenc_sichitiu_dutta_mushi_2023, title={AERIQ: SDR-Based LTE I/Q Measurement and Analysis Framework for Air-to-Ground Propagation Modeling}, ISSN={["1095-323X"]}, DOI={10.1109/AERO55745.2023.10115787}, abstractNote={In this paper, we introduce AERIQ: a software-defined radio (SDR) based I/Q measurement and analysis framework for wireless signals for aerial experimentation. AERIQ is integrated into controllable aerial vehicles, it is flexible, repeatable, and provides raw I/Q samples for post-processing the data to extract various key parameters of interest (KPIs) over a 3D volume. Using SDRs, we collect I/Q data with unmanned aerial vehicles (UAVs) flying at various altitudes in a radio dynamic zone (RDZ) like outdoor environment, from a 4G LTE eNB that we configure to operate at 3.51 GHz. Using the raw I/Q samples, and using Matlab's LTE Toolbox, we provide a step-by-step description for frequency offset estimation/correction, synchronization, cell search, channel estimation, and reference signal received power (RSRP). We provide various representative results for each step, such as RSRP measurements and corresponding analytical approximation at different UAV altitudes, coherence bandwidth and coherence time of the channel at different UAV altitudes and link distances, and kriging based 3D RSRP interpolation. The collected raw data as well as the software developed for obtaining and post-processing such data are provided publicly for potential use by other researchers. AERIQ is also available in emulation and testbed environments for external researchers to access and use as part of the NSF AERPAW platform at NC State University.}, journal={2023 IEEE AEROSPACE CONFERENCE}, author={Maeng, S. J. and Ozdemir, O. and Guvenc, I. and Sichitiu, M. L. and Dutta, R. and Mushi, M.}, year={2023} }
 @article{raouf_maeng_guvenc_ozdemir_sichitiu_2023, title={Cellular Spectrum Occupancy Probability in Urban and Rural Scenarios at Various UAS Altitudes}, ISSN={["2166-9570"]}, DOI={10.1109/PIMRC56721.2023.10293763}, abstractNote={The ever-growing demand for wireless connectivity, coupled with limited spectrum resources, has resulted in spectrum congestion and interference. This research investigates the probability of occupancy in common sub-6 GHz cellular network bands based on measurements conducted in urban and rural environments. Specifically, we analyze the spectrum occupancy of various long-term evolution (LTE), 5th generation (5G) and Citizens Broadband Radio Service (CBRS) bands used in the United States, considering both uplink and downlink transmissions at altitudes up to 180 meters. Additionally, we explore the influence of altitude on the probability of spectrum occupancy in these bands. Our findings reveal that the probability of occupancy is generally higher in the downlink compared to the uplink. Moreover, we observe that line-of-sight (LoS) signals play a critical role in higher altitudes. These results provide insights spectrum utilization in various cellular bands across different altitudes, with implications on interference and spectrum coexistence between terrestrial networks and unmanned aerial systems (UASs) in the future.}, journal={2023 IEEE 34TH ANNUAL INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, PIMRC}, author={Raouf, Amir Hossein Fahim and Maeng, Sung Joon and Guvenc, Ismail and Ozdemir, Ozgur and Sichitiu, Mihail}, year={2023} }
 @article{gurses_funderburk_kesler_powell_rahman_ozdemir_mushi_sichitiu_guvenc_dutta_et al._2023, title={Demonstration of Joint SDR/UAV Experiment Development in AERPAW}, ISSN={["2155-7578"]}, url={http://dx.doi.org/10.1109/milcom58377.2023.10356351}, DOI={10.1109/MILCOM58377.2023.10356351}, abstractNote={The Aerial Experimentation and Research Platform for Advanced Wireless (AERPAW) is an outdoor testbed providing the experimenters access to programmable radios and programmable vehicles. A key aspect of AERPAW is its experiment development environment. This demo introduces potential users to the main capabilities of AERPAW’s development environment. The demo exercises the main three flexible testbed capabilities, namely the ability of an experimenter to choose a wireless radio setup, a vehicle setup, and to set up traffic. The experiment is then executed live, and the collected data is post-processed and displayed.}, journal={MILCOM 2023 - 2023 IEEE MILITARY COMMUNICATIONS CONFERENCE}, author={Gurses, Anil and Funderburk, Mark and Kesler, John and Powell, Keith and Rahman, Talha F. and Ozdemir, Ozgur and Mushi, Magreth and Sichitiu, Mihail L. and Guvenc, Ismail and Dutta, Rudra and et al.}, year={2023} }
 @article{drago_gurses_heath_sichitiu_zorzi_2023, title={End-to-end Full-Stack Drone Measurements: A Case Study Using AERPAW}, ISSN={["2164-7038"]}, url={http://dx.doi.org/10.1109/iccworkshops57953.2023.10283735}, DOI={10.1109/ICCWORKSHOPS57953.2023.10283735}, abstractNote={While $a$ lot of studies have been made to include drone communications in the 5th Generation of Mobile Networks (5G), it is still arguable how reliably current air-to-ground infrastructures can perform. To apply a further boost to this research direction, the National Science Foundation (NSF) recently funded the Aerial Experimentation Research Platform for Advanced Wireless (AERPAW) for the creation of a high-end publicly available testbed. Considering the current lack in the literature of experimental studies carried out with open testbeds, in this paper we target two contributions. First, we use AERPAW for the end-to-end evaluation of the performance of an emulated Uplink (UL) traffic between an Unmanned Aerial Vehicle (UAV) and a Fixed Node (FN), connected through an open source LTE network software (srsRAN). Second, in addition to providing a thorough analysis of the results obtained from our experiments, we made our testbed's configuration files and collected dataset available to the public, to provide a reference for future research on UAV communication, enabled by AERPAW.}, journal={2023 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS WORKSHOPS, ICC WORKSHOPS}, author={Drago, Matteo and Gurses, Anil and Heath, Robert W., Jr. and Sichitiu, Mihail L. and Zorzi, Michele}, year={2023}, pages={1422–1427} }
 @article{maeng_ozdemir_guvenc_sichitiu_mushi_dutta_2023, title={LTE I/Q Data Set for UAV Propagation Modeling, Communication, and Navigation Research}, volume={61}, ISSN={["1558-1896"]}, DOI={10.1109/MCOM.005.2200784}, abstractNote={Unmanned aerial vehicles (UAVs) have recently been gaining considerable attention due to their vast range of potential applications. To facilitate UAV use cases involving beyond visual line of sight (BVLOS), cellular networks have emerged as ground connectivity points, enabling remote control and payload communication for UAV links. However, the availability of limited datasets obstructs the study of cellular technology coverage for UAV flights at different altitudes and the development of machine learning (ML) techniques for improving UAV communication and navigation. In this article, we introduce raw LTE in-phase and quadrature (I/Q) sample data sets obtained from physical field experiments of the NSF AERPAW experimentation platform. A UAV equipped with a software-defined radio (SDR) was flown at altitudes ranging from 30 m to 110 m, collecting raw I/Q samples from an SDR-based LTE base station operating at 3.51 GHz. We have implemented a standardized metadata format that can be used to replicate the results obtained from the collected datasets. The post-processing of raw I/Q samples is described and representative results are provided. In the end, we give examples of potential uses of the provided dataset, post-processing sample code, and I/Q collection sample experiment code by other ML, wireless, and UAV researchers.}, number={9}, journal={IEEE COMMUNICATIONS MAGAZINE}, author={Maeng, Sung Joon and Ozdemir, Ozgur and Guvenc, Ismail and Sichitiu, Mihail L. and Mushi, Magreth and Dutta, Rudra}, year={2023}, month={Sep}, pages={90–96} }
 @article{singh_sichitiu_guvenc_bhuyan_2023, title={Minimizing Ground Risk in Cellular-Connected Drone Corridors With mmWave Links}, volume={59}, ISSN={["1557-9603"]}, url={https://doi.org/10.1109/TAES.2023.3301824}, DOI={10.1109/TAES.2023.3301824}, abstractNote={Unmanned Aircraft Systems (UASs) have been receiving significant interest and support from academia, industry, and regulatory bodies over the past decade due to their various use cases. To safely integrate UAS operations into the national airspace, particularly overpopulated regions, the risk posed to ground users, buildings, and vehicles due to unmanned aerial vehicle (UAV) flight should be minimized. This risk can be represented by a numerical metric, which we refer to in this article as the “ground risk.” Many UAS applications also depend on the presence of a reliable wireless communication link between the UAV and a control station for the transmission of UAV position, surveillance video, UAV payload commands, and other mission-related data. Such wireless communication requirements also need to be considered in the design of UAS operations. In this article, we consider both these aspects and study the design of nonintersecting trajectories for UAS operations to minimize ground risk, subject to constraints on the wireless signal strength and geometry of the trajectory, specified in terms of: 1) an enclosing cylinder within which the trajectory must lie and 2) an integrated angular change along the UAV's trajectory. The performance of a computationally expensive optimal algorithm is compared with that of a computationally faster heuristic approach within the dense urban environment of Manhattan, NY, USA. Performance evaluation using ray-tracing simulations shows that the heuristic approach performs close to the optimal algorithm at a reduced computation cost. This research can be utilized to make UAS operations safe and reliable and accelerate their adoption.}, number={6}, journal={IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS}, author={Singh, Simran and Sichitiu, Mihail L. and Guvenc, Ismail and Bhuyan, Arupjyoti}, year={2023}, month={Dec}, pages={7923–7937} }
 @article{maeng_ozdemir_nandakumar_guvenc_sichitiu_dutta_mushi_2023, title={Spectrum Activity Monitoring and Analysis for Sub-6 GHz Bands Using a Helikite}, ISSN={["2155-2487"]}, DOI={10.1109/COMSNETS56262.2023.10041314}, abstractNote={In this paper, we report sub-6 GHz spectrum measurement results at multiple ground fixed nodes and a helikite flying at altitudes up to 500 feet. Measurements are carried out at the NSF AERPAW platform in Raleigh, NC. We first describe our measurement methodology using software defined radios (SDRs) and explain the details of the measurement environment. Subsequently, we analyze the impact of terrain, measurement altitude, measurement frequency, and the time of the day on spectrum measurements for various different sub-6 GHz bands. In particular, we present spectrum occupancy results from various different LTE bands first in a rural environment, and then in an urban campus environment. Results show that for both environments, measured power at a given spectrum band increases with altitude up to 500 feet. On the other hand, in the urban environment, an abrupt increase in the aggregate received power is observed in all considered bands as the helikite rises above the buildings, when compared with the more gradual increase of the received power in same bands for the rural environment.}, journal={2023 15TH INTERNATIONAL CONFERENCE ON COMMUNICATION SYSTEMS & NETWORKS, COMSNETS}, author={Maeng, S. J. and Ozdemir, O. and Nandakumar, H. N. and Guvenc, I. and Sichitiu, M. L. and Dutta, R. and Mushi, M.}, year={2023} }
 @article{raouf_maeng_guvenc_ozdemir_sichitiu_2023, title={Spectrum Monitoring and Analysis in Urban and Rural Environments at Different Altitudes}, ISSN={["2577-2465"]}, DOI={10.1109/VTC2023-Spring57618.2023.10200994}, abstractNote={Due to the scarcity of spectrum resources, the emergence of new technologies and ever-increasing number of wireless devices operating in the radio frequency spectrum lead to data congestion and interference. In this work, we study the effect of altitude on sub-6 GHz spectrum measurement results obtained at a Helikite flying over two distinct scenarios; i.e., urban and rural environments. Specifically, we aim at investigating the spectrum occupancy of various long-term evolution (LTE), 5th generation (5G) and citizens broadband radio service (CBRS) bands utilized in the United States for both uplink and downlink at altitudes up to 180 meters. Our results reveal that generally the mean value of the measured power increases as the altitude increases where the line-of-sight links with nearby base stations is more available. SigMF-compliant spectrum measurement datasets used in this paper covering all the bands between 100 MHz to 6 GHz are also provided.}, journal={2023 IEEE 97TH VEHICULAR TECHNOLOGY CONFERENCE, VTC2023-SPRING}, author={Raouf, Amir Hossein Fahim and Maeng, Sung Joon and Guvenc, Ismail and Ozdemir, Ozgur and Sichitiu, Mihail}, year={2023} }
 @article{du_mujumdar_ozdemir_ozturk_guvenc_sichitiu_dai_bhuyan_2022, title={60 GHz Outdoor Propagation Measurements and Analysis Using Facebook Terragraph Radios}, ISSN={["2164-2958"]}, DOI={10.1109/RWS53089.2022.9719957}, abstractNote={The high attenuation of millimeter-wave (mmWave) would significantly reduce the coverage areas, and hence it is critical to study the propagation characteristics of mmWave in multiple deployment scenarios. In this work, we investigated the propagation and scattering behavior of 60 GHz mmWave signals in outdoor environments at a travel distance of 98 m for an aerial link (rooftop to rooftop), and 147 m for a ground link (light-pole to light-pole). Measurements were carried out using Facebook Terragraph (TG) radios. Results include received power, path loss, signal-to-noise ratio (SNR), and root mean square (RMS) delay spread for all beamforming directions supported by the antenna array. Strong line-of-sight (LOS) propagation exists in both links. We also observed rich multipath components (MPCs) due to edge scatterings in the aerial link, while only LOS and ground reflection MPCs in the other link.}, journal={2022 IEEE RADIO AND WIRELESS SYMPOSIUM (RWS)}, author={Du, Kairui and Mujumdar, Omkar and Ozdemir, Ozgur and Ozturk, Ender and Guvenc, Ismail and Sichitiu, Mihail L. and Dai, Huaiyu and Bhuyan, Arupjyoti}, year={2022}, pages={156–159} }
 @article{funderburk_kesler_sridhar_sichitiu_guvenc_dutta_zajkowski_marojevic_2022, title={AERPAW Vehicles: Hardware and Software Choices}, DOI={10.1145/3539493.3539583}, abstractNote={AERPAW (Aerial Experimentation and Research Platform for Advanced Wireless) is an advanced wireless research platform centered around fully programmable radios and fully programmable vehicles. In this paper we detail the vehicle aspects of the testbed, including the AERPAW UAVs, UGVs, as well as the hardware and software choices made by the team, as well as our experience earned in the past few years.}, journal={PROCEEDINGS OF THE 2022 EIGHTH WORKSHOP ON MICRO AERIAL VEHICLE NETWORKS, SYSTEMS, AND APPLICATIONS, DRONET 2022}, author={Funderburk, Mark and Kesler, John and Sridhar, Keshav and Sichitiu, Mihail L. and Guvenc, Ismail and Dutta, Rudra and Zajkowski, Thomas and Marojevic, Vuk}, year={2022}, pages={37–42} }
 @article{samal_dutta_guvenc_sichitiu_floyd_zajkowski_2022, title={Automating Operator Oversight in an Autonomous, Regulated, Safety-Critical Research Facility}, ISSN={["1095-2055"]}, DOI={10.1109/ICCCN54977.2022.9868858}, abstractNote={The deployment at scale of Unmanned Aerial Systems have become increasingly imminent in the last few years, even as concerns regarding the dependability and predictability of their command and control channels remain fully to be addressed. The intersection of ground-to-air wireless communications, aerial networking, and trajectory control has become a research area of sharp interest. The validation of such research, beyond the theoretical/simulation stage, requires a facility that is both realistic, and admits of potentially risky or unsafe operation, while in the end guaranteeing personnel and equipment safety. The AERPAW project is an ambitious project, funded by the PAWR program of the US NSF, to create a remote accessible research platform for a research facility to enable such validation. To enable remote usage of such a testbed, yet provide the researcher with complete experimental freedom, the AERPAW facility includes a combination of architectural mechanisms that balance freedom of experimentation with regulatory compliance and safety. In this paper, we articulate the challenges and considerations of designing such mechanisms, and present the architectural features of AERPAW that attempt to realize these lofty goals.}, journal={2022 31ST INTERNATIONAL CONFERENCE ON COMPUTER COMMUNICATIONS AND NETWORKS (ICCCN 2022)}, author={Samal, Tripti and Dutta, Rudra and Guvenc, Ismail and Sichitiu, Mihail L. and Floyd, Brian and Zajkowski, Thomas}, year={2022} }
 @article{maeng_guvenc_sichitiu_floyd_dutta_zajkowski_ozdemir_mushi_2022, title={National Radio Dynamic Zone Concept with Autonomous Aerial and Ground Spectrum Sensors}, ISSN={["2164-7038"]}, DOI={10.1109/ICCWORKSHOPS53468.2022.9814648}, abstractNote={National radio dynamic zone (NRDZs) are intended to be geographically bounded areas within which controlled experiments can be carried out while protecting the nearby licensed users of the spectrum. An NRDZ will facilitate research and development of new spectrum technologies, waveforms, and protocols, in typical outdoor operational environments of such technologies. In this paper, we introduce and describe an NRDZ concept that relies on a combination of autonomous aerial and ground sensor nodes for spectrum sensing and radio environment monitoring (REM). We elaborate on key characteristics and features of an NRDZ to enable advanced wireless experimentation while also coexisting with licensed users. Some preliminary results based on simulation and experimental evaluations are also provided on out-of-zone leakage monitoring and real-time REMs.}, journal={2022 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS WORKSHOPS (ICC WORKSHOPS)}, author={Maeng, S. J. and Guvenc, I and Sichitiu, M. L. and Floyd, B. and Dutta, R. and Zajkowski, T. and Ozdemir, O. and Mushi, M.}, year={2022}, pages={687–692} }
 @article{maeng_guvenc_sichitiu_ozdemir_2022, title={Out-of-Zone Signal Leakage Sensing in Radio Dynamic Zones}, ISSN={["1550-3607"]}, DOI={10.1109/ICC45855.2022.9838534}, abstractNote={Radio dynamic zones (RDZs) are geographically bounded areas where novel advanced wireless technologies can be developed, tested, and improved, without the concern of interfering to other incumbent radio technologies nearby the RDZ. In order to operate an RDZ, use of a real-time spectrum monitoring system carries critical importance. Such a monitoring system should detect out-of-zone (OoZ) signal leakage outside of the RDZ, and if the interference to nearby receivers is intolerable, the monitoring system should be capable of mitigating such interference. This can e.g. be achieved by stopping operations inside the RDZ or switching to other bands for RDZ operation. In this paper, we introduce a spectrum monitoring concept for OoZ signal leakage detection at RDZs, where sensor nodes (SNs) are installed at the boundary of an RDZ and monitor the power leakage from multiple transmitters within the RDZ. We propose a prediction algorithm that estimates the received interference at OoZ geographical locations outside of the RDZ, using the measurements obtained at sparsely located SNs at the RDZ boundary. Using computer simulations, we evaluate the performance of the proposed algorithm and study its sensitivity to SN deployment density.}, journal={IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC 2022)}, author={Maeng, Sung Joon and Guvenc, Ismail and Sichitiu, Mihail L. and Ozdemir, Ozgur}, year={2022}, pages={5579–5584} }
 @article{mushi_joshi_dutta_guvenc_sichitiu_floyd_zajkowski_2022, title={The AERPAW Experiment Workflow - Considerations for Designing Usage Models for a Computing-supported Physical Research Platform}, ISSN={["2159-4228"]}, DOI={10.1109/INFOCOMWKSHPS54753.2022.9798061}, abstractNote={The AERPAW project is an ambitious project, funded by the PAWR program of the US NSF, to create a remote accessible research platform for a research facility with some distinct features that makes its usage model unique, and non-obvious to many researchers desirous of making use of this platform. AERPAW is primarily a physical resource (not a computing or cyber-resource) - the RF enviroment, and the airspace. Experimenters can explore them through radio transceivers and Unmanned Aerial Vehicles, both under the Experimenter’s programmatic control. Since the entire workflow of the user is through the mediation of virtual computing environments, users often tend to think of AERPAW as a computing resource, and find some of the experiment workflow counter-intuitive. In this paper, we articulate the challenges and considerations of designing an experiment workflow that balances the need for guaranteeing safe testbed operation, and providing flexible programmatic access to this unique resource.}, journal={IEEE INFOCOM 2022 - IEEE CONFERENCE ON COMPUTER COMMUNICATIONS WORKSHOPS (INFOCOM WKSHPS)}, author={Mushi, Magreth and Joshi, Harshvardhan P. and Dutta, Rudra and Guvenc, Ismail and Sichitiu, Mihail L. and Floyd, Brian and Zajkowski, Thomas}, year={2022} }
 @article{chowdhury_anjinappa_guvenc_sichitiu_ozdemir_bhattacherjee_dutta_marojevic_floyd_2021, title={A Taxonomy and Survey on Experimentation Scenarios for Aerial Advanced Wireless Testbed Platforms}, volume={2021-March}, ISSN={["1095-323X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85111405299&partnerID=MN8TOARS}, DOI={10.1109/AERO50100.2021.9438449}, abstractNote={There are various works in the recent literature on fundamental research and experimentation on unmanned aerial vehicle (UAV) communications. On the other hand, to our best knowledge, there is no taxonomy and survey on experimentation possibilities with a software-defined aerial wireless platform. The goal of this paper is first to have a brief overview of large-scale advanced wireless experimentation platforms broadly available to the wireless research community, including also the Aerial Experimentation and Research Platform for Advanced Wireless (AERPAW). We then provide a detailed taxonomy and a comprehensive survey of experimentation possibilities that can be carried out in a platform such as AERPAW. In particular, we conceptualize and present eleven different classes of advanced and aerial wireless experiments, provide several example experiments for each class, and discuss some of the existing related works in the literature. The paper will help to develop a better understanding of the equipment and software resources that can be available for experimentation in mid-scale wireless platforms, as well as the capabilities and limitations of such platforms.}, journal={2021 IEEE AEROSPACE CONFERENCE (AEROCONF 2021)}, author={Chowdhury, Md Moin Uddin and Anjinappa, Chethan K. and Guvenc, Ismail and Sichitiu, Mihail and Ozdemir, Ozgur and Bhattacherjee, Udita and Dutta, Rudra and Marojevic, Vuk and Floyd, Brian}, year={2021} }
 @article{panicker_ozdemir_sichitiu_guvenc_dutta_marojevic_floyd_2021, title={AERPAW emulation overview and preliminary performance evaluation}, volume={194}, ISSN={["1872-7069"]}, url={https://doi.org/10.1016/j.comnet.2021.108083}, DOI={10.1016/j.comnet.2021.108083}, abstractNote={The Aerial Experimentation and Research Platform for Advanced Wireless (AERPAW) has been recently funded by the National Science Foundation (NSF)'s Platforms for Advanced Wireless Research (PAWR) program. The AERPAW platform will enable experiments with programmable radios and programmable unmanned aerial vehicles (UAVs), conducted in a safe and repeatable manner. Several architectural components are crucial for enabling the envisioned capabilities of the testbed. In this paper, after providing a high level overview of AERPAW, we first present the emulation design of AERPAW vehicles. Subsequently, we describe various different options for wireless channel emulation in AERPAW. We start with a generalized model for wireless emulation, and expand that model to packet-level emulation, I-Q level emulation, and radio-frequency (RF)-level emulation. A discussion on the trade-offs among these various different emulation possibilities is also provided.}, journal={COMPUTER NETWORKS}, publisher={Elsevier BV}, author={Panicker, Ashwin and Ozdemir, Ozgur and Sichitiu, Mihail L. and Guvenc, Ismail and Dutta, Rudra and Marojevic, Vuk and Floyd, Brian}, year={2021}, month={Jul} }
 @article{singh_lee_tran_zhou_sichitiu_guvenc_bhuyan_2021, title={FPV Video Adaptation for UAV Collision Avoidance}, volume={2}, ISSN={["2644-125X"]}, url={https://doi.org/10.1109/OJCOMS.2021.3106274}, DOI={10.1109/OJCOMS.2021.3106274}, abstractNote={First person view (FPV) technology for unmanned aerial vehicles (UAVs) provides an immersive experience for pilots and enables various personal and commercial applications such as aerial photography, drone racing, search and rescue operations, agricultural surveillance, and structural inspection. While real time video streaming from a UAV and vision-based collision avoidance strategies have been studied in literature as separate topics, in this paper we tackle collision avoidance in FPV scenarios, taking into account network delays and real time video parameters. We present a theoretical model for obstacle collisions that considers the current communication channel conditions, the real time video parameters, and the UAV’s position relative to the closest obstacle. A video adaptation algorithm is then designed, using this metric, to tune the FPV video resolution, number of re-transmission attempts, and the modulation scheme to maximize the probability of avoiding collisions. This algorithm also takes into account specific latency constraints of the application. This video algorithm was evaluated in various scenarios and its ability to respond to both distances to the obstacle as well as the communication channel conditions was demonstrated. It was found that, for the considered scenarios, the performance of the proposed adaptive algorithm was, on an average, 58.63% higher than the closest non-adaptive one in terms of maximizing the probability of avoiding collision. Such collision avoidance strategies could be used to make UAV FPV applications safer and more reliable.}, journal={IEEE OPEN JOURNAL OF THE COMMUNICATIONS SOCIETY}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Singh, Simran and Lee, Hee Won and Tran, Tuyen X. and Zhou, Yu and Sichitiu, Mihail L. and Guvenc, Ismail and Bhuyan, Arupjyoti}, year={2021}, pages={2095–2110} }
 @article{singh_bhattacherjee_ozturk_guvenc_dai_sichitiu_bhuyan_2021, title={Placement of mmWave Base Stations for Serving Urban Drone Corridors}, DOI={10.1109/VTC2021-Spring51267.2021.9448923}, abstractNote={As the use of unmanned aerial vehicles (UAVs) in various commercial, civil, and military applications increases, it becomes important to study the design of aerial drone corridors that can support multiple simultaneous UAV missions. In this work, we study the placement of base stations (BSs) to serve aerial drone corridors while satisfying specific UAV mission requirements, such as the geometrical waypoints for the UAV to fly through and the minimum data rate to be supported along the mission trajectory. We develop a mathematical model of the drone corridor and propose a brute force algorithm that leverages A* search to meet the quality of service (QoS) requirements of the corridor by choosing the minimal set of BS locations from a pre-determined initial set. Using raytracing simulations, BS placement results are presented for various antenna array sizes in a dense urban region in East Manhattan. It was found that, for the scenario under consideration, a single BS equipped with an 8x8 antenna array is sufficient to satisfy the given QoS requirements of the corridor, while two BSs are required when using 4x4 antenna arrays.}, journal={2021 IEEE 93RD VEHICULAR TECHNOLOGY CONFERENCE (VTC2021-SPRING)}, author={Singh, Simran and Bhattacherjee, Udita and Ozturk, Ender and Guvenc, Ismail and Dai, Huaiyu and Sichitiu, Mihail and Bhuyan, Arupjyoti}, year={2021} }
 @article{bhuyan_guvenc_dai_sichitiu_singh_rahmati_maeng_2021, title={Secure 5G Network for a Nationwide Drone Corridor}, ISSN={["1095-323X"]}, DOI={10.1109/AERO50100.2021.9438162}, abstractNote={5G can provide the multiplicative capacity gains needed to support a large number of drones/UAS (Unmanned Aircraft Systems). 5G cellular networks with newly available millimeter wave (mmWave) frequency bands can provide wireless communication links for control as well as data traffic for drones and drone swarms. Drones are becoming increasingly important for commercial uses such as delivery and transportation as well as for public safety search and rescue of natural disaster victims, surveillance of remote critical infrastructure, surveys of environmental quality in protected regions, and detection of threats during major public events. This paper presents research findings in the following areas critical to validating the effectiveness of providing required 5G access to the drones with security, reliability, and spectral efficiency: 1) Radio coverage for the drone corridor by adding a separate set of antennas for coverage in the air while the conventional set of antennas continues to provide coverage on the ground. Beam transmission and validation with ray-tracing simulations are covered. 2) Optimization of uplink communication from a swarm of drones with a single mmWave beam by grouping the drones with power allocations for non-orthogonal multiple access (NOMA). 3) Optimization of the network lifetime of a swarm of drones resulting in suitable trajectories in the presence of interference. 4) Methods including precoding that can enhance physical layer security with channel information about the interference source. The paper concludes with plans for future research to provide further scientific basis for the proposed cellular drone network.}, journal={2021 IEEE AEROSPACE CONFERENCE (AEROCONF 2021)}, author={Bhuyan, Arupjyoti and Guvenc, Ismail and Dai, Huaiyu and Sichitiu, Mihail L. and Singh, Simran and Rahmati, Ali and Maeng, Sung Joon}, year={2021} }
 @article{xiong_sichitiu_2019, title={A Lightweight Localization Solution for Small, Low Resources WSNs}, volume={8}, url={https://doi.org/10.3390/jsan8020026}, DOI={10.3390/jsan8020026}, abstractNote={The increasing demand for location-dependent services in wireless sensor networks (WSNs) calls for solutions capable of handling the diversified demands and the unique challenges presented in WSNs. In most applications, nodes need to determine their locations in a reliable manner while operating under stringent constraints in computation, communication, and energy resources. This paper offers a novel solution to bridge the gap between the high accuracy demand and low resources available for range-based localization. We propose KickLoc, a fully distributed scheme, which considers the uncertainty of the distance measurements to minimize localization errors introduced from the range measurement, and leverages information from all neighboring nodes for better position estimations. Our work is evaluated via extensive simulations, with comparisons to other well-known localization schemes, and the Cramér-Rao lower bound (CRLB). In addition, we implement and evaluate the proposed system on sensor platforms with different range measurement mechanisms. The results show that this localization solution outperforms existing methods in various scenarios, while remains lightweight and suitable for small, low resources WSNs.}, number={2}, journal={Journal of Sensor and Actuator Networks}, publisher={MDPI AG}, author={Xiong, Hong and Sichitiu, Mihail L.}, year={2019}, month={May}, pages={26} }
 @article{singh_atrey_sichitiu_viniotis_2019, title={Clearer than Mud: Extending Manufacturer Usage Description (MUD) for Securing IoT Systems}, volume={11519}, ISBN={["978-3-030-23356-3"]}, ISSN={["1611-3349"]}, DOI={10.1007/978-3-030-23357-0_4}, abstractNote={Internet of Things (IoT) devices, expected to increase exponentially over the next several years, are easy targets for attackers. To make these devices more secure, the IETF's draft of Manufacturer Usage Description (MUD) provides a means for the manufacturer of an IoT device to specify its intended purpose and communication patterns in terms of access control lists (ACLs), thereby defining the device's normal behaviour. However, MUD may not be sufficient to comprehensively capture the normal behaviour specification, as it cannot incorporate variable operational settings that depend on the environment. Further, MUD only supports limited features. Our approach overcomes these limitations by allowing the administrator to define the normal behaviour by choosing combinations from a wider set of features that includes physical layer parameters, values of packet headers, and flow statistics. We developed and implemented a learning-based system that captures and demodulates wireless packets from IoT devices over a period of time, extracts the features specified in the normal behaviour specification, and uses a learning algorithm to create a normal model of each device. Our implementation also enforces these normal models by detecting violations and taking appropriate actions, in terms of ACLs on an Internet Gateway, against the misbehaving devices. Hence, our framework makes the specification tighter and clearer than what is possible with MUD alone, thereby making IoT systems more secure.}, journal={INTERNET OF THINGS - ICIOT 2019}, author={Singh, Simran and Atrey, Ashlesha and Sichitiu, Mihail L. and Viniotis, Yannis}, year={2019}, pages={43–57} }
 @article{qi_sichitiu_2019, title={Physical Layer Performance of a Cooperative Amplify and Forward Scheme for MIMO WLANs}, volume={68}, ISSN={["1939-9359"]}, DOI={10.1109/TVT.2019.2916375}, abstractNote={This paper proposes a novel cooperative amplify and forward (CAF) architecture for MIMO WLANs to improve their coverage and transmission rates, without requiring any modifications in the IEEE 802.11 standards at the clients. System models are used for analyzing the physical layer of CAF networks, and compared with the conventional amplify-and-forward (AF) and decode-and-forward (DF) networks. Numerical results demonstrate that the CAF network clearly outperforms conventional 802.11 networks, and AF and DF networks in terms of coverage and throughput.}, number={7}, journal={IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY}, author={Qi, Yuepeng and Sichitiu, Mihail L.}, year={2019}, month={Jul}, pages={6709–6720} }
 @article{koohifar_guvenc_sichitiu_2018, title={Autonomous Tracking of Intermittent RF Source Using a UAV Swarm}, volume={6}, ISSN={["2169-3536"]}, url={http://dx.doi.org/10.1109/access.2018.2810599}, DOI={10.1109/access.2018.2810599}, abstractNote={The localization of a radio-frequency transmitter with intermittent transmissions is considered via a group of unmanned aerial vehicles (UAVs) equipped with omnidirectional received signal strength sensors. This group embarks on an autonomous patrol to localize and track the target with a specified accuracy, as quickly as possible. The challenge can be decomposed into two stages: 1) estimation of the target position given previous measurements (localization) and 2) planning the future trajectory of the tracking UAVs to get lower expected localization error given current estimation (path planning). For each stage, we compare two algorithms in terms of performance and computational load. For the localization stage, we compare a detection-based extended Kalman filter (EKF) and a recursive Bayesian estimator. For the path planning stage, we compare a steepest descent posterior Cramer–Rao lower bound path planning and a bioinspired heuristic path planning. Our results show that the steepest descent path planning outperforms the bioinspired path planning by an order of magnitude, and recursive Bayesian estimator narrowly outperforms detection-based EKF.}, journal={IEEE ACCESS}, author={Koohifar, Farshad and Guvenc, Ismail and Sichitiu, Mihail L.}, year={2018}, pages={15884–15897} }
 @article{carpenter_sichitiu_2018, title={BUR-GEN: A Bursty Packet Generator for Vehicular Communication Channels}, volume={67}, ISSN={["1939-9359"]}, DOI={10.1109/TVT.2018.2866946}, abstractNote={Common vehicular channel models (VCMs) accurately predict the packet reception ratio (PRR) observed from dedicated short-range communication (DSRC) field operational tests. However, such independent and identically distributed (i.i.d.) based packet generation models fail to match the bursty channel conditions that result in occasional long periods of packet losses that thwart the ability of safety applications to assist drivers in improving their situational awareness. In this paper, we propose a bursty packet generation algorithm called BUR-GEN, which we evaluate through simulation and, along with several common VCMs, compare to the PRR, inter-packet gap (IPG), and consecutive reception run length (CRRL) of the safety pilot model deployment, a large-scale DSRC-based measurement campaign. The model that incorporates the BUR-GEN packet generation algorithm improves the root-mean-square error of IPG and CRRL by factors of six and four, respectively. Additionally, we assess safety effectiveness using awareness probability. Our results show that safety reliability estimates for vehicle-to-vehicle safety applications are increased by a factor of 31 for maximum safety tolerances, as compared to an i.i.d.-based model that produces that same PRR but does not account for bursty channel behaviors.}, number={11}, journal={IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY}, author={Carpenter, Scott E. and Sichitiu, Mihail L.}, year={2018}, month={Nov}, pages={10232–10242} }
 @article{detection, tracking, and interdiction for amateur drones_2018, url={http://dx.doi.org/10.1109/mcom.2018.1700455}, DOI={10.1109/mcom.2018.1700455}, abstractNote={Unmanned aerial vehicles, also known as drones, are expected to play major roles in future smart cities, for example, by delivering goods and merchandise, serving as mobile hotspots for broadband wireless access, and maintaining surveillance and security. The goal of this survey article is to study various potential cyber and physical threats that may arise from the use of UAVs, and subsequently review various ways to detect, track, and interdict malicious drones. In particular, we review techniques that rely on ambient radio frequency signals (emitted from UAVs), radars, acoustic sensors, and computer vision techniques for detection of malicious UAVs. We present some early experimental and simulation results on range estimation of UAVs and receding horizon tracking of UAVs. Finally, we summarize common techniques that are considered for interdiction of UAVs.}, journal={IEEE Communications Magazine}, year={2018}, month={Apr} }
 @article{li_sichitiu_qiu_2019, title={Fog Radio Access Network: A New Wireless Backhaul Architecture for Small Cell Networks}, volume={7}, ISSN={["2169-3536"]}, DOI={10.1109/ACCESS.2018.2886449}, abstractNote={In this paper, we develop a novel wireless backhauling strategy for small-cell networks based on dynamic base station (BSs) cooperation, which we call the fog-radio access network (F-RAN) backhauling strategy. By taking advantage of fog-computing, our proposed strategy enables BSs to combine and process signals received from diverse paths, which can significantly increase the transmission efficiency of the backhaul network. We first model an F-RAN-enabled network and three existing backhauling strategies, namely, direct transmission, decode and forward, and cloud-RAN. We then analyze and compare the performance of these strategies. The numerical results show that our proposed strategy provides the highest throughput for cell edge users while maintaining the same performance in most of the other areas. Moreover, for dense small-cell networks with poor backhaul channels, F-RAN outperforms all other strategies.}, journal={IEEE ACCESS}, author={Li, Zifan and Sichitiu, Mihail L. and Qiu, Xuesong}, year={2019}, pages={14150–14161} }
 @article{carpenter_sichitiu_2017, title={Evaluating the Accuracy of Vehicular Channel Models in a Large-Scale DSRC Test}, ISSN={["2155-6806"]}, DOI={10.1109/mass.2017.19}, abstractNote={Vehicle-to-vehicle channel characteristics differ significantly from those of conventional cellular channels, especially in terms of fading statistics due to varying environmental conditions, link types, vehicle types, and objects that result in complex propagation effects. Accurate modeling of the vehicular channel remains a complex challenge. In this paper, existing, common vehicular channel models (VCMs) are evaluated and compared to measurement data from the UMTRI large-scale Dedicated Short-Range Communications (DSRC) testbed involving nearly 3000 vehicles and conducted over several months around Ann Arbor, MI. While many VCMs can predict reasonably well the frequent packet error rates observed near Ann Arbor, they over-estimate inter-packet gap and under-estimate the likelihood of runs of consecutively and successfully received packets. The testbed environment shows significant fading (i.e., sub-Rayleigh) and/or shadowing effects that challenge the accuracy of traditional VCMs. Furthermore, despite 60% of the inter-vehicle paths being obstructed by items available using OpenStreetMap (OSM) geodata, a deterministic obstacle shadowing model that makes use of such geodata does not account for all shadowing effects. Evaluating vehicular channel models in terms of real-world, large-scale experiments helps researchers better understand actual behaviors and allows for the development of new and/or improved models that more accurately reflect reality.}, journal={2017 IEEE 14TH INTERNATIONAL CONFERENCE ON MOBILE AD HOC AND SENSOR SYSTEMS (MASS)}, author={Carpenter, Scott E. and Sichitiu, Mihail L.}, year={2017}, pages={241–249} }
 @article{lee_sichitiu_thuente_2017, title={NEAT: Network link emulation with adaptive time dilation}, volume={104}, ISSN={["1096-0848"]}, DOI={10.1016/j.jpdc.2017.01.013}, abstractNote={In evaluating the performance of highly complex networked systems, emulation is often used as it maintains much of the realism of testbeds, while offering increased flexibility and scalability. In large emulation systems, multiple and heterogeneous virtual machines can be deployed in relatively few general purpose physical hosts. Time dilation is a technique that allows virtual time to pass at a different (and potentially variable) rate with respect to real time, allowing for increased scalability of the emulated system. In this paper we present networking links in a large emulated system employing adaptive time dilation. The link emulation focuses on accurate delay and throughput emulation while allowing varying time dilation factors. To evaluate our system, we measure the delay and throughput of the virtual links under variable system loads.}, journal={JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING}, author={Lee, Hee Won and Sichitiu, Mihail L. and Thuente, David}, year={2017}, month={Jun}, pages={88–98} }
 @article{gong_sichitiu_2017, title={On the Accuracy of Pairwise Time Synchronization}, volume={16}, ISSN={["1558-2248"]}, DOI={10.1109/twc.2017.2671862}, abstractNote={Time synchronization is a fundamental problem in any distributed system. In particular, wireless sensor networks require scalable time synchronization for implementing distributed tasks on multiple sensor nodes. Different synchronization schemes and hardware systems are able to achieve widely different levels of synchronization accuracy. Since synchronization accuracy is very sensitive to random delays and clock rate fluctuations, we model the pairwise synchronization error as a function of random delays and clock drifts to quantitatively model synchronization performance as a function of the relevant parameters, such as the beacon interval, the number of beacons per synchronization period, and the measurement point. The synchronization error is analyzed for different state-of-the-art pairwise synchronization schemes, based on one-way sender–receiver, two-way sender–receiver, and receiver–receiver approaches, using application layer or medium access control layer timestamping. The models are validated through numerical and experimental results.}, number={4}, journal={IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS}, author={Gong, Fengyuan and Sichitiu, Mihail L.}, year={2017}, month={Apr}, pages={2664–2677} }
 @article{gong_sichitiu_2017, title={Temperature compensated Kalman distributed clock synchronization}, volume={62}, ISSN={["1570-8713"]}, DOI={10.1016/j.adhoc.2017.04.009}, abstractNote={Time synchronization is a fundamental problem in any distributed system. In particular, wireless sensor networks (WSNs) require scalable time synchronization for implementing distributed tasks on multiple sensor nodes. We propose a temperature-compensated Kalman based distributed synchronization protocol (TKDS) using a two-way sender-receiver synchronization scheme, to achieve high synchronization accuracy while modelling the clock skew change based on its physical characteristics. By asynchronously combining estimates from neighbours, TKDS achieves better performance than the spanning tree based protocols in a fully-distributed fashion. The synchronization performance is evaluated numerically and compared with that of other well-known synchronization protocols.}, journal={AD HOC NETWORKS}, author={Gong, Fengyuan and Sichitiu, Mihail L.}, year={2017}, month={Jul}, pages={88–100} }
 @article{bozkurt_lobaton_sichitiu_2016, title={A Biobotic Distributed Sensor Network for Under-Rubble Search and Rescue}, volume={49}, ISSN={["1558-0814"]}, url={http://dx.doi.org/10.1109/mc.2016.136}, DOI={10.1109/mc.2016.136}, abstractNote={Utilizing the latest neural engineering developments, researchers have enabled biobotic insects that function as search-and-rescue agents to help map under-rubble environments and locate survivors and hazardous conditions. The Web extra at http://youtu.be/oJXEPcv-FMw is a video in which authors Alper Bozkurt, Edgar Lobaton, and Mihail Sichitiu demonstrate the acoustic steering of roach biobots to search for disaster victims trapped under rubble.}, number={5}, journal={COMPUTER}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Bozkurt, Alper and Lobaton, Edgar and Sichitiu, Mihail}, year={2016}, month={May}, pages={38–46} }
 @inproceedings{carpenter_sichitiu_2016, title={Analysis of packet loss in a large-scale DSRC field operational test}, DOI={10.1109/pemwn.2016.7842909}, abstractNote={Dedicated Short-Range Communication (DSRC) intends to improve transportation safety by using wireless technology to allow vehicles to exchange safety-awareness message between them. Using a large empirical dataset collected from a field operational test of nearly 3000 vehicles operating around Ann Arbor, Michigan, we characterize the packet-level performance of safety messages exchanged among vehicular encounters. Specifically, to better understand the real-world operating conditions of the vehicular wireless channel, the characteristics of Packet Reception Ratio (PRR) and Inter-Packet Gap (IPG) behaviors and temporal and spatial correlations are examined. Analysis of vehicle-pair encounters shows DSRC packet losses differing from other, static-node wireless beaconing networks, due mainly to the vehicles' high mobility and the possibilities of signal scatterers and/or obstructers that may come between them. As long bursts of consecutively lost packets could jeopardize vehicle safety awareness, IPG is explored further, with short-gapped consecutive losses commonly uncorrelated and longer gaps exhibiting temporal correlation tendencies. The findings of this paper can be used to inform channel models for DSRC systems, which in turn can produce meaningful simulation results.}, booktitle={5th IFIP International Conference On Performance Evaluation And Modeling In Wired And Wireless Networks Pemwn 16}, author={Carpenter, S. E. and Sichitiu, Mihail L.}, year={2016} }
 @inproceedings{xiong_latif_lobaton_bozkurt_sichitiu_2016, title={Characterization of RSS variability for biobot localization using 802.15.4 radios}, DOI={10.1109/wisnet.2016.7444305}, abstractNote={A cyber-physically organized swarm of insect biobots or biological robots can aid first responders in search-and-rescue scenarios after natural disasters or earthquakes by establishing an under-rubble sensor network. In such a network, the nodes are represented by the insect biobots equipped with electronic backpacks utilizing a system-on-chip. This application requires effective real-time localization of the mobile sensor nodes. Radio signal strength (RSS) is a measurement of the received signal power, and can be used in estimating the distance between two nodes, which then can help localize the biobotic sensor nodes in the future. This paper investigates RSS variability and its suitability for biobotic localization.}, booktitle={2016 ieee topical conference on wireless sensors and sensor networks (wisnet)}, author={Xiong, H. and Latif, T. and Lobaton, E. and Bozkurt, A. and Sichitiu, Mihail L.}, year={2016}, pages={1–3} }
 @inproceedings{xiong_sichitiu_2016, title={KickLoc: Simple, distributed localization for wireless sensor networks}, DOI={10.1109/mass.2016.037}, abstractNote={The emergence of location-based applications in wireless sensor network has galvanized extensive research on localization. Nonetheless, localization remains a difficult problem due to trade-offs between accuracy, energy consumption and computing resources. Searching for a solution that is sufficiently robust to handle a variety of scenarios, we propose KickLoc, which is a fully distributed solution. KickLoc takes the reliability of distance measurements into account to mitigate errors resulting from distance measurement errors, and fuses information from all neighboring nodes to provide position estimates. We evaluated the proposed algorithms both through simulations and experiments, the results are compared with other localization schemes and the Cramer-Rao lower bound (CRLB). The results show that the proposed algorithms outperform existing solutions in most of scenarios, while requiring significantly lower resources.}, booktitle={Proceedings 2016 ieee 13th international conference on mobile ad hoc and sensor systems (mass 2016)}, author={Xiong, H. and Sichitiu, Mihail L.}, year={2016}, pages={228–236} }
 @inproceedings{latif_gong_dickey_sichitiu_bozkurt_2016, title={Using liquid metal alloy (EGaIn) to electrochemically enhance SS stimulation electrodes for biobotic applications}, DOI={10.1109/embc.2016.7591152}, abstractNote={Biobotics is an emerging and useful advent in the field of robotics which harnesses the mechanical power of live invertebrates and benefits from them as "working" animals. Most biobotic applications rely on neural or muscular stimulation through implanted electrodes for achieving direct control of their locomotory behavior. Degradation of stimulation efficiency is often noticed through extended usage, partly owing to incompatibility of implanted electrodes to the application. Our previous achievements in biobotics utilized commercially available stainless steel wires as stimulation electrodes due to its availability and lower cost. In this study, we look into the potential of using a liquid metal alloy, eutectic gallium-indium (EGaIn), as a means of enhancing properties of the stainless steel electrodes and its first time consideration as in vivo neurostimulation electrodes. We present in vitro analysis of the electrodes in terms of the electrolyte-electrode interface impedance and interface equivalent circuit model.}, booktitle={2016 38th annual international conference of the ieee engineering in medicine and biology society (embc)}, author={Latif, T. and Gong, F. Y. and Dickey, Michael and Sichitiu, Mihail L. and Bozkurt, A.}, year={2016}, pages={2141–2144} }
 @article{gong_sichitiu_2016, title={CESP: A Low-Power High-Accuracy Time Synchronization Protocol}, volume={65}, ISSN={["1939-9359"]}, DOI={10.1109/tvt.2015.2417810}, abstractNote={Time synchronization is a fundamental problem in any distributed system. In particular, wireless sensor networks (WSNs) require scalable time synchronization for implementing distributed tasks on multiple sensor nodes. We propose an energy-efficient coefficient exchange synchronization protocol (CESP) based on a receiver-receiver synchronization scheme, which minimizes the impact of access-time delays. Most of the existing synchronization protocols focus on improving the synchronization accuracy by assuming the availability of packet-level timestamping and with little concern for power consumption. The proposed time-synchronization protocol achieves high synchronization accuracy similar to the classic reference broadcast synchronization (RBS) protocol without requiring packet-level timestamping but with a significant reduction on communication overhead to achieve low power consumption. CESP works in a fundamentally different way from RBS: In order to synchronize two receivers, RBS exchanges all beacon packets between two receivers, whereas CESP receivers first process a large number of received beacon packets and only then exchange a small amount of information between the two receivers: synchronization coefficients. The synchronization performance and power consumption are evaluated and compared with that of other well-known synchronization protocols through experimental results.}, number={4}, journal={IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY}, author={Gong, Fengyuan and Sichitiu, Mihail L.}, year={2016}, month={Apr}, pages={2387–2396} }
 @article{pandian_sichitiu_dai_2015, title={Optimal Resource Allocation in Random Access Cooperative Cognitive Radio Networks}, volume={14}, ISSN={["1558-0660"]}, DOI={10.1109/tmc.2014.2343968}, abstractNote={Cooperative cognitive radio networks (CCRNs) incorporates cooperative communication into cognitive radio networks, in which, primary users lease their spectrum to secondary users, and in exchange, the primary users leverage secondary users as cooperative relays to enhance their own throughput. Mobile operators offload their Internet traffic to privately owned Wi-Fi access points (APs), much to the inconvenience of non-cellular users served by the APs. However, by employing the CCRN scheme, the mobile operator can lease a licensed channel to the AP, effectively doubling its capacity. In this paper, we propose an implementation of the CCRN framework applied to IEEE 802.11 WLANs. The cooperation is cast as a two-player bargaining game where the two players are the primary users (users of the mobile operator) and the secondary users (users of the AP before spectrum leasing) who bargain for either throughput share or channel access time share. The optimal resource allocation that ensures efficiency as well as fairness among users is provided by the Nash solution. Simulation results show that the users achieve higher throughput via the proposed CCRN scheme, thus providing the mobile operator (e.g., AT&T) and the private Wi-Fi provider (e.g., a Starbucks coffee shop) with incentives for cooperation.}, number={6}, journal={IEEE TRANSACTIONS ON MOBILE COMPUTING}, author={Pandian, Mani Bharathi and Sichitiu, Mihail L. and Dai, Huaiyu}, year={2015}, month={Jun}, pages={1245–1258} }
 @article{bozkurt_lobaton_sichitiu_hedrick_latif_dirafzoon_whitmire_verderber_marin_xiong_et al._2014, title={Biobotic Insect Swarm based Sensor Networks for Search and Rescue}, volume={9091}, ISSN={["1996-756X"]}, url={http://dx.doi.org/10.1117/12.2053906}, DOI={10.1117/12.2053906}, abstractNote={The potential benefits of distributed robotics systems in applications requiring situational awareness, such as search-and-rescue in emergency situations, are indisputable. The efficiency of such systems requires robotic agents capable of coping with uncertain and dynamic environmental conditions. For example, after an earthquake, a tremendous effort is spent for days to reach to surviving victims where robotic swarms or other distributed robotic systems might play a great role in achieving this faster. However, current technology falls short of offering centimeter scale mobile agents that can function effectively under such conditions. Insects, the inspiration of many robotic swarms, exhibit an unmatched ability to navigate through such environments while successfully maintaining control and stability. We have benefitted from recent developments in neural engineering and neuromuscular stimulation research to fuse the locomotory advantages of insects with the latest developments in wireless networking technologies to enable biobotic insect agents to function as search-and-rescue agents. Our research efforts towards this goal include development of biobot electronic backpack technologies, establishment of biobot tracking testbeds to evaluate locomotion control efficiency, investigation of biobotic control strategies with Gromphadorhina portentosa cockroaches and Manduca sexta moths, establishment of a localization and communication infrastructure, modeling and controlling collective motion by learning deterministic and stochastic motion models, topological motion modeling based on these models, and the development of a swarm robotic platform to be used as a testbed for our algorithms.}, journal={SIGNAL PROCESSING, SENSOR/INFORMATION FUSION, AND TARGET RECOGNITION XXIII}, publisher={SPIE}, author={Bozkurt, A. and Lobaton, E. and Sichitiu, Mihail L. and Hedrick, T. and Latif, T. and Dirafzoon, A. and Whitmire, E. and Verderber, A. and Marin, J. and Xiong, H. and et al.}, editor={Kadar, IvanEditor}, year={2014} }
 @article{lee_sichitiu_thuente_2015, title={High-performance emulation of heterogeneous systems using adaptive time dilation}, volume={29}, ISSN={["1741-2846"]}, DOI={10.1177/1094342014554789}, abstractNote={ Building a testbed for evaluating the performance of large-scale heterogeneous systems can be costly and inefficient. Emulation is often used to evaluate the performance of a system in a controlled environment. Time dilation allows virtual machines (VMs) to emulate higher performance than that of their physical machine. We present an approach using adaptive time dilation to emulate large-scale distributed systems composed of heterogeneous machines and Operating Systems (OSs). In our implementation, VMs are globally synchronized. To evaluate our system, distributed VMs running Linux, Windows, FreeBSD, and Junos are emulated on general-purpose physical machines. }, number={2}, journal={INTERNATIONAL JOURNAL OF HIGH PERFORMANCE COMPUTING APPLICATIONS}, author={Lee, Hee Won and Sichitiu, Mihail L. and Thuente, David}, year={2015}, pages={166–183} }
 @inproceedings{integrated simulation and emulation using adaptive time dilation_2014, url={http://dx.doi.org/10.1145/2601381.2601384}, DOI={10.1145/2601381.2601384}, abstractNote={Simulation and emulation techniques are commonly used to evaluate the performance of complex networked systems. Simulation conveniently predicts the behavior of a complex networked system while usually requiring fewer simplifying model assumptions often necessary for theoretical analysis. In contrast, emulation does not need to re-implement the target real systems, so it may improve on the implementation efficiency of simulation while maintaining much of the realism of testbeds. A hybrid approach in which simulation nodes connect to emulation hosts can be used to combine the advantages of both approaches. In this paper, we propose integrating simulation with emulation using adaptive time dilation to evaluate system performance. If a simulator schedules its events in real time and the simulation time keeps up with the real time, then the hybrid system works very well and meets its deadlines. However, a heavily-loaded simulator can introduce significant simulation delays and thereby create situations where these delays impact the accuracy of the system. Our approach uses time dilation to reduce simulation delays and thus increasing the accuracy of the integrated simulation and emulation system. Our adaptive time dilation dynamically controls the time dilation factor to avoid system overloads for both the simulation and the emulation components and to improve the execution correctness of the hybrid system.}, booktitle={Proceedings of the 2nd ACM SIGSIM/PADS conference on Principles of advanced discrete simulation - SIGSIM-PADS '14}, year={2014} }
 @article{lim_jang_sichitiu_2015, title={MCAS-MAC: A multichannel asynchronous scheduled MAC protocol for wireless sensor networks}, volume={56}, ISSN={["1873-703X"]}, DOI={10.1016/j.comcom.2014.10.008}, abstractNote={Due to their energy efficiency, many duty cycling-based MAC protocols have been proposed in WSNs. Although these protocols considerably reduce energy consumption by minimizing idle listening and overhearing, the energy efficiency comes at the cost of decreased packet delivery ratio and increased delay. In this paper, we present a multichannel asynchronous scheduled MAC protocol, called MCAS-MAC, which inherits the basic asynchronous scheduling operation from AS-MAC and adds back-to-back packet transmissions and multichannel support for high traffic dense WSN. Using RaPTEX, we evaluate the performance of MCAS-MAC by comparing it with existing duty cycling MAC protocols including BMAC, SMAC and AS-MAC.}, journal={COMPUTER COMMUNICATIONS}, author={Lim, Jun Bum and Jang, Beakcheol and Sichitiu, Mihail L.}, year={2015}, month={Feb}, pages={98–107} }
 @article{zhao_sichitiu_rhee_2015, title={N-body: A social mobility model with support for larger populations}, volume={25}, ISSN={["1570-8713"]}, DOI={10.1016/j.adhoc.2014.10.005}, abstractNote={An accurate reproduction of real human movement is essential in simulations of MANETs in order to obtain meaningful performance results. Existing models capturing real world mobility features often require knowledge of the underlying dynamics of the target scenario, therefore limiting the application scope. In this paper we tackle this problem from a different perspective. Rather than considering the details of the target scenario, we extract features from a sample trace, and synthesize traces that have similar features. In particular, as human activities are often socially organized, resulting in a tendency of forming groups, we propose an N-body mobility model that captures the group forming tendency from traces of a small number of nodes, and reproduces them in mobility traces of a larger population. Through simulation we show that the N-body model is capable of synthesizing the group forming behavior similar to that observed from sample traces.}, journal={AD HOC NETWORKS}, author={Zhao, Chen and Sichitiu, Mihail L. and Rhee, Injong}, year={2015}, month={Feb}, pages={185–196} }
 @article{jang_lim_sichitiu_2013, title={An asynchronous scheduled MAC protocol for wireless sensor networks}, volume={57}, ISSN={["1872-7069"]}, DOI={10.1016/j.comnet.2012.09.002}, abstractNote={Wireless sensor networks (WSNs) comprise a number of autonomous sensors and one or more sinks to cooperatively monitor physical or environmental conditions. Energy efficiency is a key design factor of a MAC protocol for WSNs. Due to the importance of the problem, a number of energy efficient MAC protocols have been developed for WSNs. Preamble-sampling based MAC protocols (e.g., B-MAC and X-MAC) have overheads due to their preambles, and are inefficient at large wakeup intervals. SCP-MAC, a synchronous scheduled energy-efficient scheduling MAC protocol, minimizes the preamble by combining preamble sampling and scheduling techniques; however, it does not prevent energy loss due to overhearing; in addition, due to its synchronization procedure, it results in increased contention and delay. In this paper, we present an energy efficient MAC protocol for WSNs that avoids overhearing and reduces contention and delay by asynchronously scheduling the wakeup time of neighboring nodes. We provide an energy consumption analysis for multi-hop networks. To validate our design and analysis, we implement the proposed scheme in TinyOS. Experimental results show that AS-MAC considerably reduces energy consumption, packet loss and delay when compared with existing energy efficient MAC protocols.}, number={1}, journal={COMPUTER NETWORKS}, author={Jang, Beakcheol and Lim, Jun Bum and Sichitiu, Mihail L.}, year={2013}, month={Jan}, pages={85–98} }
 @article{jang_sichitiu_2012, title={IEEE 802.11 Saturation Throughput Analysis in the Presence of Hidden Terminals}, volume={20}, ISSN={["1558-2566"]}, DOI={10.1109/tnet.2011.2165322}, abstractNote={Due to its usefulness and wide deployment, IEEE 802.11 has been the subject of numerous studies, but still lacks a complete analytical model. Hidden terminals are common in IEEE 802.11 and cause the degradation of throughput. Despite the importance of the hidden terminal problem, there have been a relatively small number of studies that consider the effect of hidden terminals on IEEE 802.11 throughput, and many are not accurate for a wide range of conditions. In this paper, we present an accurate new analytical saturation throughput model for the infrastructure case of IEEE 802.11 in the presence of hidden terminals. Simulation results show that our model is accurate in a wide variety of cases.}, number={2}, journal={IEEE-ACM TRANSACTIONS ON NETWORKING}, author={Jang, Beakcheol and Sichitiu, Mihail L.}, year={2012}, month={Apr}, pages={557–570} }
 @article{kim_sichitiu_2011, title={Optimal Max-Min Fair Resource Allocation in Multihop Relay-Enhanced WiMAX Networks}, volume={60}, ISSN={["1939-9359"]}, DOI={10.1109/tvt.2011.2163431}, abstractNote={In this paper, an optimal resource allocation scheme is proposed for WiMAX networks that are enhanced with nontransparent relay stations (RSs). We first focus on two-hop relaying networks, because this scenario has the largest throughput gain. Furthermore, several researchers have proposed different resource allocation schemes in two-hop relaying networks, and thus, we can compare the performance of our proposed scheme with the following two well-known schemes in terms of cell throughput, outage rate, and computational time: 1) orthogonal and 2) overlapped . We then explore an extension of the proposed scheme to a general multihop relaying scenario by taking into account spatial reuse in both the access and relay zone periods. The numerical results show that the highest cell throughput can be achieved by the proposed optimal scheme while maintaining the fairness and lower outage performance of the orthogonal scheme at a higher computational cost. Moreover, the cell throughput degradation from increasing the number of hops from two to three hops, under the proposed optimal scheduling scheme, is only 12% and 19% when six and nine RSs are deployed, respectively.}, number={8}, journal={IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY}, author={Kim, Yongchul and Sichitiu, Mihail L.}, year={2011}, month={Oct}, pages={3907–3918} }
 @article{kim_sichitiu_2011, title={Optimal Placement of Transparent Relay Stations in 802.16j Mobile Multihop Relay Networks}, volume={E94B}, ISSN={["1745-1345"]}, DOI={10.1587/transcom.e94.b.2582}, abstractNote={WiMAX (IEEE 802.16) has emerged as a promising radio access technology for providing high speed broadband connectivity to subscribers over large geographic regions. New enhancements allow deployments of relay stations (RSs) that can extend the coverage of the base station (BS), increase cell capacity, or both. In this paper, we consider the placement of transparent RSs that maximize the cell capacity. We provide a closed-form approximation for the optimal location of RS inside a cell. A numerical analysis of a number of case studies validates the closed-form approximation. The numerical results show that the closed-form approximation is reasonably accurate. key words: WiMAX, relay networks, optimal placement}, number={9}, journal={IEICE TRANSACTIONS ON COMMUNICATIONS}, author={Kim, Yongchul and Sichitiu, Mihail L.}, year={2011}, month={Sep}, pages={2582–2591} }
 @inproceedings{kim_sichitiu_2011, title={Optimal resource allocation in multihop relay-enhanced WiMAX networks}, DOI={10.1109/wcnc.2011.5779254}, abstractNote={Multihop relaying in WiMAX networks is considered an increasingly attractive technology for providing throughput enhancement, coverage extension, or both. In this paper, we consider deploying non-transparent relay stations (RSs) that transmit on the same carrier frequency as the base station (BS) for the purpose of coverage extension. Since it is possible that the RSs and BS are transmitting/receiving simultaneously to/from the subscriber stations (SSs) during the access zone period, it is challenging to schedule resources optimally for serving SSs in a fair manner. We propose an optimal scheduling scheme that preserves fairness among active SSs, and compare its performance with two different resource allocation schemes, namely, the overlapped and orthogonal in terms of cell throughput and outage performance. Our numerical results show that proposed scheme can achieve more throughput than the orthogonal scheme, while maintaining the fairness and lower outage performance of the orthogonal one.}, booktitle={2011 IEEE Wireless Communications and Networking Conference (WCNC)}, author={Kim, Y. and Sichitiu, Mihail L.}, year={2011}, pages={737–742} }
 @article{zhao_sichitiu_2011, title={Contact time in random walk and random waypoint: Dichotomy in tail distribution}, volume={9}, ISSN={["1570-8713"]}, DOI={10.1016/j.adhoc.2010.03.005}, abstractNote={Contact time (or link duration) is a fundamental factor that affects performance in Mobile Ad Hoc Networks. Previous research on theoretical analysis of contact time distribution for random walk models (RW) assume that the contact events can be modeled as either consecutive random walks or direct traversals, which are two extreme cases of random walk, thus with two different conclusions. In this paper we conduct a comprehensive research on this topic in the hope of bridging the gap between the two extremes. The conclusions from the two extreme cases will result in a power-law or exponential tail in the contact time distribution, respectively. However, we show that the actual distribution will vary between the two extremes: a power-law-sub-exponential dichotomy, whose transition point depends on the average flight duration. Through simulation results we show that such conclusion also applies to random waypoint.}, number={2}, journal={AD HOC NETWORKS}, author={Zhao, Chen and Sichitiu, Mihail L.}, year={2011}, month={Mar}, pages={152–163} }
 @inproceedings{kim_sichitiu_2010, title={Fairness schemes in 802.16j mobile multihop relay networks}, DOI={10.1109/glocom.2010.5683326}, abstractNote={Multihop relaying in WiMAX networks is considered a cost effective way to extend the coverage of the base stations, increase cell capacity, or both. In this paper, we consider deploying non-transparent relay stations for coverage extension and study the issue of fairness schemes in such networks. Since there are access and relay zones in both downlink and uplink frames and simultaneous transmissions are possible in the access zone, it is challenging to schedule resources optimally for serving subscriber stations in a fair manner. We evaluate the performance of well known fairness schemes such as max-min and proportional fairness in such networks. We also propose a new scheduling scheme, named subsection fairness that can achieve better throughput than traditional fairness schemes by maximizing bandwidth utilization. Our numerical results evaluate the performance of each scheduling scheme in terms of cell throughput and fairness.}, booktitle={2010 ieee global telecommunications conference globecom 2010}, author={Kim, Y. C. and Sichitiu, Mihail L.}, year={2010} }
 @article{lim_jang_yoon_sichitiu_dean_2010, title={RaPTEX: Rapid Prototyping Tool for Embedded Communication Systems}, volume={7}, ISSN={["1550-4859"]}, DOI={10.1145/1806895.1806902}, abstractNote={Advances in microprocessors, memory, and radio technology have enabled the emergence of embedded systems that rely on communication systems to exchange information and coordinate their activities in spatially distributed applications. However, developing embedded communication systems that satisfy specific application requirements is a challenge due to the many tradeoffs imposed by different choices of underlying protocols and their parameters. Furthermore, evaluating the correctness and performance of the design and implementation before deploying it is a nontrivial task due to the complexity of the resulting system. This article presents the design and implementation of RaPTEX, a rapid prototyping tool for embedded communication systems, especially well suited for wireless sensor networks (WSNs), consisting of three major subsystems: a toolbox, an analytical performance estimation framework, and an emulation environment. We use a hierarchical approach in the design of the toolbox to facilitate the composition of the network stack. For fast exploration of the tradeoff space at design time, we build an analytical performance estimation model for energy consumption, delay, and throughput. For realistic performance evaluation, we design and implement a hybrid, accurate, yet scalable, emulation environment. Through three use cases, we study the tradeoff space for different protocols and topologies, and highlight the benefits of using RaPTEX for designing and evaluating embedded communication systems for WSNs.}, number={1}, journal={ACM TRANSACTIONS ON SENSOR NETWORKS}, author={Lim, Jun Bum and Jang, Beakcheol and Yoon, Suyoung and Sichitiu, Mihail L. and Dean, Alexander G.}, year={2010}, month={Aug} }
 @article{xie_zhang_sichitiu_fu_yao_2010, title={Feasibility of optimally assigning channels by exhaustive search in commercial multi-radio wireless mesh networks}, volume={44}, ISSN={["1018-4864"]}, DOI={10.1007/s11235-009-9216-3}, number={1-2}, journal={TELECOMMUNICATION SYSTEMS}, author={Xie, Wei and Zhang, Ying Jun and Sichitiu, Mihail L. and Fu, Liqun and Yao, Yan}, year={2010}, month={Jun}, pages={171–178} }
 @article{jun_sichitiu_2008, title={MRP: Wireless mesh networks routing protocol}, volume={31}, ISSN={["1873-703X"]}, DOI={10.1016/j.comcom.2008.01.038}, abstractNote={Wireless Mesh Networks (WMNs) are one of the few commonly implemented types of mobile ad-hoc networks (MANETs); several companies offer WMNs for broadband Internet access and for extending the coverage of wireless local area networks. Several particularities differentiate WMNs from MANETs. First, in WMNs, most of the traffic originates or terminates at the gateways (nodes connected to the wired infrastructure/Internet). Second, in most applications, WMN nodes tend to be neatly differentiated as either stationary nodes (providing connectivity and coverage) or mobile nodes (utilizing the coverage afforded by the stationary nodes). While general MANET routing protocols can be used in WMNs, it is expected that a protocol that takes the particularities of WMNs into account will outperform the general protocol. In this paper, we propose such a routing protocol and evaluate its performance via simulations. Results show that, for WMNs, the proposed routing protocol outperforms general purpose MANET protocols in terms of routing overhead, packet delivery ratio, network throughput, end-to-end delay, and average hop-count.}, number={7}, journal={COMPUTER COMMUNICATIONS}, author={Jun, Jangeun and Sichitiu, Mihail L.}, year={2008}, month={May}, pages={1413–1435} }
 @article{taggart_viniotis_sichitiu_2009, title={Modeling the effect of node synchronization times in ultra-wideband wireless networks}, volume={66}, ISSN={["1872-745X"]}, DOI={10.1016/j.peva.2008.10.008}, abstractNote={Ultra-wideband wireless (UWB) can provide the physical layer for high-throughput personal area networks. When UWB is used for communication between many nodes, relatively long acquisition times are needed when dropping and re-establishing wireless links between the nodes. This paper describes the development and use of mathematical and simulation models to investigate the impact of dropping and reacquiring links between nodes on average packet delay; we also consider the performance of the alternative strategy of forwarding packets through intermediate nodes without breaking the established wireless links. The work presented here assumes that no specific MAC layer protocol, such as WiMedia UWB MAC, is in operation. The paper describes the models, explains the selection of modeling parameters used, compares the average packet delay for a network of three simple UWB nodes and for a ring of ten UWB nodes and explains the use of these results for network design engineers.}, number={3-5}, journal={PERFORMANCE EVALUATION}, author={Taggart, Christopher S. and Viniotis, Yannis and Sichitiu, Mihail L.}, year={2009}, month={Mar}, pages={223–239} }
 @article{rhee_warrier_aia_min_sichitiu_2008, title={Z-MAC: A hybrid MAC for wireless sensor networks}, volume={16}, ISSN={["1558-2566"]}, DOI={10.1109/TNET.2007.900704}, abstractNote={This paper presents the design, implementation and performance evaluation of a hybrid MAC protocol, called Z-MAC, for wireless sensor networks that combines the strengths of TDMA and CSMA while offsetting their weaknesses. Like CSMA, Z-MAC achieves high channel utilization and low latency under low contention and like TDMA, achieves high channel utilization under high contention and reduces collision among two-hop neighbors at a low cost. A distinctive feature of Z-MAC is that its performance is robust to synchronization errors, slot assignment failures, and time-varying channel conditions; in the worst case, its performance always falls back to that of CSMA. Z-MAC is implemented in TinyOS.}, number={3}, journal={IEEE-ACM TRANSACTIONS ON NETWORKING}, author={Rhee, Injong and Warrier, Ajit and Aia, Mahesh and Min, Jeongki and Sichitiu, Mihail L.}, year={2008}, month={Jun}, pages={511–524} }
 @inbook{kihl_sichitiu_ekeroth_rozenberg_2007, title={Reliable Geographical Multicast Routing in Vehicular Ad-Hoc Networks}, ISBN={9783540726944 9783540726975}, url={http://dx.doi.org/10.1007/978-3-540-72697-5_27}, DOI={10.1007/978-3-540-72697-5_27}, abstractNote={Vehicular ad-hoc networks (VANETs) offer a large number of new potential applications without relying on significant infrastructure. Many of these applications benefit from multi-hop relaying of information, thus requiring a routing protocol. Characteristics unique to VANETs (such as high mobility and the need for geographical addressing) make many conven tional ad hoc routing protocols unsuitable. Also, some envisioned applica tions have end-to-end QoS requirements. In this paper we propose a new multicast routing protocol specifically designed for VANETs. Its purpose is to provide a routing service for a future reliable transport protocol. We eval uate its performance using realistic network and traffic models. It is shown that it is possible to implement a reliable multicast routing protocol for VANETs.}, booktitle={Lecture Notes in Computer Science}, publisher={Springer Berlin Heidelberg}, author={Kihl, Maria and Sichitiu, Mihail and Ekeroth, Ted and Rozenberg, Michael}, year={2007}, month={Jun}, pages={315–325} }
 @article{yoon_veerarittiphan_sichitiu_2007, title={Tiny-sync: Tight time synchronization for wireless sensor networks}, volume={3}, ISSN={["1550-4867"]}, DOI={10.1145/1240226.1240228}, abstractNote={Time synchronization is a fundamental middleware service for any distributed system. Wireless sensor networks make extensive use of synchronized time in many contexts (e.g., data fusion, TDMA schedules, synchronized sleep periods, etc.). We propose a time synchronization method relevant for wireless sensor networks. The solution features minimal complexity in network bandwidth, storage as well as processing, and can achieve good accuracy. Especially relevant for sensor networks, it also provides tight, deterministic bounds on offset and clock drift. A method for synchronizing the entire network is presented. The performance of the algorithm is analyzed theoretically and validated on a realistic testbed. The results show that the proposed algorithm outperforms existing algorithms in terms of precision and resource requirements.}, number={2}, journal={ACM TRANSACTIONS ON SENSOR NETWORKS}, author={Yoon, Suyoung and Veerarittiphan, Chanchai and Sichitiu, Mihail L.}, year={2007}, month={Jun} }
 @article{visweswara_dutta_sichitiu_2006, title={Adaptive ad hoc self-organizing scheduling for quasi-periodic sensor network lifetime}, volume={29}, ISSN={["1873-703X"]}, DOI={10.1016/j.comcom.2006.01.037}, abstractNote={Wireless sensor networks are poised to revolutionize our abilities in sensing and controlling our environment. Power conservation is a primary research concern for these networks. Often, the single most important savings can be obtained by switching off the wireless receiver when not needed. In this paper, we describe an algorithm which allows the nodes to learn the behavior of each other by only observing the transmission behaviors, and from this derive the schedule without external help. Our approach is robust to statistical variations in the nodal transmission periods. We draw important conclusions on the effect of quasi-periodicity on the scalability of the solution. We provide results of numerical simulations that show the effectiveness of our approach.}, number={17}, journal={COMPUTER COMMUNICATIONS}, author={Visweswara, Sharat C. and Dutta, Rudra and Sichitiu, Mihail L.}, year={2006}, month={Nov}, pages={3366–3384} }
 @article{sichitiu_bauer_2006, title={Asymptotic stability of congestion control systems with multiple sources}, volume={51}, ISSN={["1558-2523"]}, DOI={10.1109/TAC.2005.863531}, abstractNote={Congestion in computer networks is the main reason for reduced performance and poor quality of service; therefore, a good congestion control system is essential. The basic property of any control system is stability. We consider the problem of stability in computer network congestion control systems with multiple sources, which is the most common case in general purpose computer networks. The main result of the note is the proof that for congestion control systems with linear controllers (e.g., ATM-ABR), the stability of the congestion control system with a single source is equivalent to the stability of the one with multiple sources. In other words, for the considered congestion control systems, if the system is stable for a single source it will be stable for an arbitrary large number of sources. The proof is based on a well-known necessary and sufficient stability test.}, number={2}, journal={IEEE TRANSACTIONS ON AUTOMATIC CONTROL}, author={Sichitiu, ML and Bauer, PH}, year={2006}, month={Feb}, pages={292–298} }
 @article{amorim_benbadis_fdida_sichitiu_viniotis_2006, title={Dissecting the routing architecture of self-organizing networks}, volume={13}, ISSN={["1558-0687"]}, DOI={10.1109/MWC.2006.275204}, abstractNote={The proper operation of self-organizing networks (SONs) relies on the autonomous behavior of their individual nodes. Routing in such networks has been a challenging task since their conception, due to their nontraditional characteristics and design requirements. Although a large amount of routing architectures and protocols for SONs has been proposed, very little work has been done on the fundamental characteristics that make a routing strategy efficient for a particular network and/or design requirement. Contrary to traditional techniques where the routing architecture is structured as a single unit, we suggest in this article that routing be thought of as a combination of four main architectural components, namely, addressing, dissemination, discovery, and forwarding. This logical decomposition offers significant advantages from both the analysis and the design perspectives. We conclude from our observations that routing architectures should be scenario-driven, in the sense that the configuration parameters are not necessarily universally good for all application scenarios}, number={6}, journal={IEEE WIRELESS COMMUNICATIONS}, author={Amorim, Marcelo and Benbadis, Farid and Fdida, Serge and Sichitiu, Mihail L. and Viniotis, Yannis}, year={2006}, month={Dec}, pages={98–104} }
 @inproceedings{jun_sichitiu_2006, title={Scalable OSPF updates for MANETs}, booktitle={Globecom 2006 - 2006 ieee global telecommunications conference}, author={Jun, J. and Sichitiu, M. L.}, year={2006} }
 @inbook{sichitiu_dutta_2005, title={Benefits of multiple battery levels for the lifetime of large wireless sensor networks}, volume={3462}, ISBN={3540258094}, DOI={10.1007/11422778_133}, abstractNote={In large wireless sensor networks, the few nodes close to the monitoring station are likely to prove the bottleneck in the useful lifetime of the network. We examine a strategy of equipping these nodes with a larger share of the total initial energy (battery) than the others, and generalizing this notion to the rest of the network. We solve a design problem involving optimizing the network lifetime using no more than a given number of distinct battery levels, and verify the results from the model by direct simulation.}, booktitle={Networking 2005: Networking technologies, services, and protocols: Performance of computer and communication networks: Mobile and wireless communication systems: 4th International IFIP-TC6 Networking Conference, Waterloo, Canada, May 2-6, 2005: Proceedings (Lecture notes in computer science; 3462)}, publisher={Berlin; New York: Springer}, author={Sichitiu, Mihail L. and Dutta, R.}, year={2005}, pages={1440–1444} }
 @inproceedings{cross-layer scheduling for power efficiency in wireless sensor networks_2004, url={http://dx.doi.org/10.1109/infcom.2004.1354585}, DOI={10.1109/infcom.2004.1354585}, abstractNote={Wireless sensor networks are considered the sensing technology of the future. Large numbers of untethered sensor nodes can be used for tracking small animals and targets, environmental monitoring, enforcing security perimeters, etc. A major problem for many sensor network applications is determining the most efficient way of conserving the energy of the power source. Some networks use batteries, while others suggest different methods of gathering energy (e.g., solar cells). Regardless of the powering method, energy conservation is of prime importance for sensor networks. The best way to conserve energy is to turn the sensor nodes off; however, since an inactive sensor node is no longer part of the network, the network can become disconnected. This creates a fundamental trade-off. In this paper, we propose a deterministic, schedule-based energy conservation scheme. In the proposed approach, time-synchronized sensors form on-off schedules that enable the sensors to be awake only when necessary. The schedule establishment is fully distributed and thus appropriate for large sensor networks. The performance of the proposed approach is evaluated through the use of simulations}, booktitle={IEEE INFOCOM 2004}, year={2004} }
 @article{sichitiu_bauer_premaratne_2003, title={The effect of uncertain time-variant delays in ATM networks with explicit rate feedback: A control theoretic approach}, volume={11}, ISSN={["1558-2566"]}, DOI={10.1109/TNET.2003.815293}, abstractNote={A new, more realistic model for the available bit rate traffic class in ATM network congestion control with explicit rate feedback is introduced and analyzed. This model is based on recent results by Ekanayake regarding discrete time models for time-variant delays. The discrete time model takes into account the effect of time-variant buffer occupancy levels of ATM switches, thus treating the case of time-variant delays between a single congested node and the connected sources. For highly dynamic situations, such a model is crucial for a valid analysis of the resulting feedback system. The new model also handles the effects of the mismatch between the resource management cell rates and the variable bit rate controller sampling rate as well as buffer and rate nonlinearities. A brief stability study shows that an equilibrium in the buffer occupancy is impossible to achieve in the presence of time-variant forward path delays. Stability conditions for the case of time-variant delays in the return path are presented. Finally, illustrative examples are provided.}, number={4}, journal={IEEE-ACM TRANSACTIONS ON NETWORKING}, author={Sichitiu, ML and Bauer, PH and Premaratne, K}, year={2003}, month={Aug}, pages={628–637} }
 @article{jun_sichitiu_2003, title={The nominal capacity of wireless mesh networks}, volume={10}, ISSN={["1558-0687"]}, DOI={10.1109/mwc.2003.1241089}, abstractNote={Wireless mesh networks are an alternative technology for last-mile broadband Internet access. In WMNs, similar to ad hoc networks, each user node operates not only as a host but also as a router; user packets are forwarded to and from an Internet-connected gateway in multihop fashion. The meshed topology provides good reliability, market coverage, and scalability, as well as low upfront investments. Despite the recent startup surge in WMNs, much research remains to be done before WMNs realize their full potential. This article tackles the problem of determining the exact capacity of a WMN. The key concept we introduce to enable this calculation is the bottleneck collision domain, defined as the geographical area of the network that bounds from above the amount of data that can be transmitted in the network. We show that for WMNs the throughput of each node decreases as O(1/n), where n is the total number of nodes in the network. In contrast with most existing work on ad hoc network capacity, we do not limit our study to the asymptotic case. In particular, for a given topology and the set of active nodes, we provide exact upper bounds on the throughput of any node. The calculation can be used to provision the network, to ensure quality of service and fairness. The theoretical results are validated by detailed simulations.}, number={5}, journal={IEEE WIRELESS COMMUNICATIONS}, author={Jun, JG and Sichitiu, ML}, year={2003}, month={Oct}, pages={8–14} }
 @article{bauer_lorand_sichitiu_premaratne_2003, title={Total delay compensation in LAN control systems and implications for scheduling}, volume={34}, ISSN={["1464-5319"]}, DOI={10.1080/00207720310001614862}, abstractNote={The first part of this paper shows that long access delays are not necessarily detrimental to the stability of local area network embedded control systems. The second part shows that (under some mild conditions on the control system) scheduling in the return path is not needed. This is a consequence of the fact that for local area networks the access delays can be exactly determined and completely eliminated from the system representation.}, number={10-11}, journal={INTERNATIONAL JOURNAL OF SYSTEMS SCIENCE}, author={Bauer, PH and Lorand, C and Sichitiu, M and Premaratne, K}, year={2003}, pages={599–605} }
 @article{bauer_sichitiu_premaratne_2002, title={Queue control under time-variant delays: A discrete time system approach}, volume={11}, DOI={10.1142/s0218126602000380}, abstractNote={ This paper introduces a discrete time model for time-variant delays and investigates the very nature of such delays. It is shown that a linear system-delay interface is a system theoretic necessity for the construction of composite linear systems with time-variant delays. Based on this analysis, two interfaces of particular importance are presented and used to obtain new, simple to check stability results for queue control systems. The relevance of the presented modeling and stability results on queue control systems to QoS control in modern communication networks is illustrated via several examples. }, number={2}, journal={Journal of Circuits, Systems, and Computers}, author={Bauer, P. H. and Sichitiu, Mihail L. and Premaratne, K.}, year={2002}, pages={187–211} }