More Like this

1. Positioning Helper Nodes to Improve Robustness of Wireless Mesh Networks to Jamming Attacks

   Feng, Jixin ; Dixon, Warren E. ; Shea, John M. ( January 2017 , IEEE Global Communications Conference)

   Wireless communication systems are susceptible to both unintentional interference and intentional jamming attacks. For mesh and ad-hoc networks, interference affects the network topology and can cause the network to partition, which may completely disrupt the applications or missions that depend on the network. Defensive techniques can be applied to try to prevent such disruptions to the network topology. Most previous research in this area is on improving network resilience by adapting the network topology when a jamming attack occurs. In this paper, we consider making a network more robust to jamming attacks before any such attack has happened. We consider a network in which the positions of most of the radios in the network are not under the control of the network operator, but the network operator can position a few “helper nodes” to add robustness against jamming. For instance, most of the nodes are radios on vehicles participating in a mission, and the helper nodes are mounted on mobile robots or UAVs. We develop techniques to determine where to position the helper nodes to maximize the robustness of the network to certain jamming attacks aimed at disrupting the network topology. Using our recent results for quickly determining how to attack a network, we use the harmony search algorithm to find helper node placements that maximize the number of jammers needed to disrupt the network 

   more » « less
2. Experimentation Framework for Wireless Communication Systems under Jamming Scenarios Dataset

   https://doi.org/10.5281/zenodo.4749668  

   Jacovic, Marko ( January 2021 , Zenodo)

   Data files were used in support of the research paper titled "“Experimentation Framework for Wireless
   Communication Systems under Jamming Scenarios" which has been submitted to the IET Cyber-Physical Systems: Theory & Applications journal. 

   Authors: Marko Jacovic, Michael J. Liston, Vasil Pano, Geoffrey Mainland, Kapil R. Dandekar
   Contact: krd26@drexel.edu

   ---------------------------------------------------------------------------------------------

   Top-level directories correspond to the case studies discussed in the paper. Each includes the sub-directories: logs, parsers, rayTracingEmulation, results. 

   --------------------------------

   logs:    - data logs collected from devices under test
       - 'defenseInfrastucture' contains console output from a WARP 802.11 reference design network. Filename structure follows '*x*dB_*y*.txt' in which *x* is the reactive jamming power level and *y* is the jaming duration in samples (100k samples = 1 ms). 'noJammer.txt' does not include the jammer and is a base-line case. 'outMedian.txt' contains the median statistics for log files collected prior to the inclusion of the calculation in the processing script. 
       - 'uavCommunication' contains MGEN logs at each receiver for cases using omni-directional and RALA antennas with a 10 dB constant jammer and without the jammer. Omni-directional folder contains multiple repeated experiments to provide reliable results during each calculation window. RALA directories use s*N* folders in which *N* represents each antenna state. 
       - 'vehicularTechnologies' contains MGEN logs at the car receiver for different scenarios. 'rxNj_5rep.drc' does not consider jammers present, 'rx33J_5rep.drc' introduces the periodic jammer, in 'rx33jSched_5rep.drc' the device under test uses time scheduling around the periodic jammer, in 'rx33JSchedRandom_5rep.drc' the same modified time schedule is used with a random jammer. 

   --------------------------------

   parsers:    - scripts used to collect or process the log files used in the study
           - 'defenseInfrastructure' contains the 'xputFiveNodes.py' script which is used to control and log the throughput of a 5-node WARP 802.11 reference design network. Log files are manually inspected to generate results (end of log file provides a summary). 
           - 'uavCommunication' contains a 'readMe.txt' file which describes the parsing of the MGEN logs using TRPR. TRPR must be installed to run the scripts and directory locations must be updated. 
           - 'vehicularTechnologies' contains the 'mgenParser.py' script and supporting 'bfb.json' configuration file which also require TRPR to be installed and directories to be updated. 

   --------------------------------

   rayTracingEmulation:    - 'wirelessInsiteImages': images of model used in Wireless Insite
               - 'channelSummary.pdf': summary of channel statistics from ray-tracing study
               - 'rawScenario': scenario files resulting from code base directly from ray-tracing output based on configuration defined by '*WI.json' file 
               - 'processedScenario': pre-processed scenario file to be used by DYSE channel emulator based on configuration defined by '*DYSE.json' file, applies fixed attenuation measured externally by spectrum analyzer and additional transmit power per node if desired
               - DYSE scenario file format: time stamp (milli seconds), receiver ID, transmitter ID, main path gain (dB), main path phase (radians), main path delay (micro seconds), Doppler shift (Hz), multipath 1 gain (dB), multipath 1 phase (radians), multipath 1 delay relative to main path delay (micro seconds), multipath 2 gain (dB), multipath 2 phase (radians), multipath 2 delay relative to main path delay (micro seconds)
               - 'nodeMapping.txt': mapping of Wireless Insite transceivers to DYSE channel emulator physical connections required
               - 'uavCommunication' directory additionally includes 'antennaPattern' which contains the RALA pattern data for the omni-directional mode ('omni.csv') and directional state ('90.csv')

   --------------------------------

   results:    - contains performance results used in paper based on parsing of aforementioned log files
    

    

   more » « less
3. Accelerated Device Placement Optimization with Contrastive Learning

   https://doi.org/10.1145/3472456.3472523  

   Lan, Hao ; Chen, Li ; Li, Baochun ( August 2021 , Proceedings of the 50th International Conference on Parallel Processing (ICPP 2021))

   models, it is difficult to fit and train a complete copy of the model on a single computational device with limited capability. Therefore, large neural networks are usually trained on a mixture of devices, including multiple CPUs and GPUs, of which the computational speed and efficiency are drastically affected by how these models are partitioned and placed on the devices. In this paper, we propose Mars, a novel design to find efficient placements for large models. Mars leverages a self-supervised graph neural network pre-training framework to generate node representations for operations, which is able to capture the topological properties of the computational graph. Then, a sequence-to-sequence neural network is applied to split large models into small segments so that Mars can predict the placements sequentially. Novel optimizations have been applied in the placer design to achieve the best possible performance in terms of the time needed to complete training the agent for placing models with very large sizes. We deployed and evaluated Mars on benchmarks involving Inception-V3, GNMT, and BERT models. Extensive experimental results show that Mars can achieve up to 27.2% and 2.7% speedup of per-step training time than the state-of-the-art for GNMT and BERT models, respectively. We also show that with self-supervised graph neural network pretraining, our design achieves the fastest speed in discovering the optimal placement for Inception-V3. 

   more » « less
4. Space-time dynamics of electricity markets incentivize technology decentralization

   https://doi.org/10.1016/j.compchemeng.2019.05.005  

   Shao, Yue ; Zavala, Victor ( January 2019 , Computers chemical engineering)

   We study economic incentives provided by space-time dynamics of day-ahead and real-time electricity markets. Specifically, we seek to analyze to what extent such dynamics promote decentralization of technologies for generation, consumption, and storage (which is essential to obtain a more flexible power grid). Incentives for decentralization are also of relevance given recent interest in the deployment of small-scale modular technologies (e.g., modular ammonia and biogas production systems). Our analysis is based on an asset placement problem that seeks to find optimal locations for generators and loads in the network that minimize profit risk. We show that an unconstrained version of this problem can be cast as an eigenvalue problem. Under this representation, optimal network allocations are eigenvectors of the space-time price covariance matrix while the eigenvalues are the associated profit variances. We also construct a more sophisticated placement formulation that captures different risk metrics and constraints on types of technologies to systematically analyze trade-offs in expected profit and risk. Our analysis reveals that space-time market dynamics provide significant incentives for decentralization and strategic asset placement but that full mitigation of risk is only possible through simultaneous investment in generation and loads (which can be achieved using batteries or microgrids). 

   more » « less
5. Universal MIMO Jammer Mitigation via Secret Temporal Subspace Embeddings

   G. Marti ; C. Studer ( October 2023 , Conference record Asilomar Conference on Signals Systems Computers)

   MIMO processing enables jammer mitigation through spatial filtering, provided that the receiver knows the spatial signature of the jammer interference. Estimating this signature is easy for barrage jammers that transmit continuously and with static signature, but difficult for more sophisticated jammers: Smart jammers may deliberately suspend transmission when the receiver tries to estimate their spatial signature, they may use time-varying beamforming to continuously change their spatial signature, or they may stay mostly silent and jam only specific instants (e.g., transmission of control signals). To deal with such smart jammers, we propose MASH, the first method that indiscriminately mitigates all types of jammers: Assume that the transmitter and receiver share a common secret. Based on this secret, the transmitter embeds (with a linear time-domain transform) its signal in a secret subspace of a higher-dimensional space. The receiver applies a reciprocal linear transform to the receive signal, which (i) raises the legitimate transmit signal from its secret subspace and (ii) provably transforms any jammer into a barrage jammer, which makes estimation and mitigation via MIMO processing straightforward. We show the efficacy of MASH for data transmission in the massive multi-user MIMO uplink. 

   more » « less