The concept of cross-layer optimization has been around for several years now. The primary goal o... more The concept of cross-layer optimization has been around for several years now. The primary goal of the cross-layer approach was to liberate the strict boundary between the layers of the traditional OSI protocol stack. This is to enable information flow between layers which then can be leveraged to optimize the network’s performance across the layers. This concept has been of keen interest for tactical application as there is an overwhelming requirement to operate in a challenging and dynamic environment. The advent of software defined radios (SDR) accelerated the growth of this domain due to the added flexibility provided by SDRs. Even with the immense interest and progress in this area of research, there has been a gaping abyss between solutions designed in theory and ones deployed in practice. To the best of our knowledge, this is the first time in literature, an embedded SDR has been leveraged to successfully design a cross-layer optimized transceiver that provides high throughpu...
2020 29th International Conference on Computer Communications and Networks (ICCCN), 2020
Multiple-input multiple-output (MIMO) systems find immense potential and applicability in the lon... more Multiple-input multiple-output (MIMO) systems find immense potential and applicability in the long term evolution (LTE), 5G, Internet of Things (IoT), vehicular ad hoc networks (VANETs), and tactical communication systems. Jamming poses significant communication hindrance as well as security risks to the wireless communication systems. The achievable rate and reliability are the two most compromised aspects of a wireless link under such severe jamming. Owing to the high capacity and reliability of MIMO systems, they are increasingly used in tactical and critical applications. Therefore, it becomes essential to assess and enhance their sustenance under hostile jamming scenarios. To this end, we address the rate and reliability requirements of a MIMO OFDM system and propose a novel rate-reliability beamformer transceiver design for highly reliable and spectrally efficient operation under the most detrimental jamming attacks. We consider the disguised all band and multiband jamming whe...
2020 14th International Conference on Signal Processing and Communication Systems (ICSPCS), 2020
Intentional and unintentional interferences collectively referred to as Radio Frequency Interfere... more Intentional and unintentional interferences collectively referred to as Radio Frequency Interference (RFI) resuit in severe security threat to the public safety, first responder emergency rescue and military missions. Such RFI if not detected and localized can disrupt the wireless communication which forms the backbone of first responder and military operations. The prime objective of this work was to design and prototype a RFI detection and localization device, Jam-Guard that significantly outperforms traditional approaches in real-life deployment yet be computationally feasible to be developed as a low SWaC (size, weight, and cost) device. The proposed device employs a unique combination of robust parallel detection algorithms based on Kurtosis and FRactional Fourier Transform (FRFT) with Golden Section Search algorithm to rapidly detect RFI that affects critical communication signais. The localization scheme is designed to leverage the FRFT output from the detection phase to ease...
Space Time Block Codes (STBCs) from orthogonal designs have attracted significant interest in rec... more Space Time Block Codes (STBCs) from orthogonal designs have attracted significant interest in recent years. However, with the growing demand for higher capacity schemes, the multiantenna transmission techniques must support and achieve higher symbol transmission rates. In this article, we focus on three and four transmit antenna schemes. For over two decades, STBC schemes for three and four transmit antennas that achieve a very high symbol transmission rate while being orthogonal, fully diverse, delay-efficient, and with very low decoding complexity have not been achieved. The schemes proposed so far trades off orthogonality, delay, diversity, or decoding complexity while achieving rate or vice-versa. This work is first of its kind to solve this problem while fulfilling all the desired properties. In this work, we carefully study the various aspects that must be considered in designing higher symbol transmission rate STBCs. The proposed designs, hereby referred to as, Jagannath sche...
2019 IEEE Cognitive Communications for Aerospace Applications Workshop (CCAAW), 2019
In this position paper, the authors argue the need for a novel framework that provides flexibilit... more In this position paper, the authors argue the need for a novel framework that provides flexibility, autonomy and optimizes the use of scarce resources to ensure reliable communication during next-generation space missions. To this end, the authors present the shortcomings of existing space architectures and the challenges in realizing adaptive autonomous space-networking. In this regard, the authors aim to jointly exploit the immense capabilities of deep reinforcement learning (DRL) and cross-layer optimization by proposing an artificial intelligence-based cognitive cross-layer decision engine to bolster next-generation space missions. The presented software-defined cognitive cross-layer decision engine is designed for the resource-constrained Internet-of-Space-Things. The framework is designed to be flexible to accommodate varying (with time and location) requirements of multiple space missions such as reliability, throughput, delay, energy-efficiency among others. In this work, th...
This paper reports on challenges and opportunities associated with the development of an electroe... more This paper reports on challenges and opportunities associated with the development of an electroencephalogram (EEG) based personalized device for monitoring of brain activities pertaining large scale neural dynamics in the observed and providing relevant feedback to the observer. The envisioned device interprets signals and categorizes them on classes of typical responses. This could enable a speechless interaction between an observer and a participant wearing the device. This framework is different from the brain-computer-interface (BCI) framework as it focuses on indicators relevant to the human observer, brain-observer-indicator (BOI). Sensors detect resting states of the brain with associated patterns, synchrony between regions, and spectral changes in response to a cognitive event. A cognitive event results in notable changes in the associated patterns of electrical potentials. Recognition of these patterns has a broad application base, if the pattern-activity mechanism is char...
This paper introduces innovative technology development that will improve performance of next-gen... more This paper introduces innovative technology development that will improve performance of next-generation cognitive wireless networking among space, air, and ground assets. The paper describes methods to develop a system where cognitive users transmit wideband spread-spectrum signals that are designed to adaptively avoid the interference dynamics of the available spectrum at the receiver. These technological advances can achieve improvement in network throughput, delay, and reliability. Theoretical performance expectations are given. The theoretical approach is translated to the construction of specific software techniques and their implementation within the cross-layer wireless communications architecture. The hardware/software testbed that simulates a dynamic Ad Hoc Software Defined Radio (SDR) network is described, and a series of tests to measure the value of the optimization techniques is given. Preliminary test results and the total expected performance improvements are shown. ...
In this position paper, we discuss the critical need for integrating zero trust (ZT) principles i... more In this position paper, we discuss the critical need for integrating zero trust (ZT) principles into next-generation communication networks (5G/6G) for both tactical and commercial applications. We highlight the challenges and introduce the concept of an intelligent zero trust architecture (i-ZTA) as a security framework in 5G/6G networks with untrusted components. While network virtualization, software-defined networking (SDN), and service-based architectures (SBA) are key enablers of 5G networks, operating in an untrusted environment has also become a key feature of the networks. Further, seamless connectivity to a high volume of devices in multi-radio access technology (RAT) has broadened the attack surface on information infrastructure. Network assurance in a dynamic untrusted environment calls for revolutionary architectures beyond existing static security frameworks. This paper presents the architectural design of an i-ZTA upon which modern artificial intelligence (AI) algorit...
Smart grids are vulnerable to cyber-attacks. This paper proposes a game-theoretic approach to eva... more Smart grids are vulnerable to cyber-attacks. This paper proposes a game-theoretic approach to evaluate the variations caused by an attacker on the power measurements. Adversaries can gain financial benefits through the manipulation of the meters of smart grids. On the other hand, there is a defender that tries to maintain the accuracy of the meters. A zero-sum game is used to model the interactions between the attacker and defender. In this paper, two different defenders are used and the effectiveness of each defender in different scenarios is evaluated. Multi-layer perceptrons (MLPs) and traditional state estimators are the two defenders that are studied in this paper. The utility of the defender is also investigated in adversary-aware and adversary-unaware situations. Our simulations suggest that the utility which is gained by the adversary drops significantly when the MLP is used as the defender. It will be shown that the utility of the defender is variant in different scenarios,...
Wireless signal recognition is becoming increasingly more significant for spectrum monitoring, sp... more Wireless signal recognition is becoming increasingly more significant for spectrum monitoring, spectrum management, and secure communications. Consequently, it will become a key enabler with the emerging fifth-generation (5G) and beyond 5G communications, Internet of Things networks, among others. State-of-the-art studies in wireless signal recognition have only focused on a single task which in many cases is insufficient information for a system to act on. In this work, for the first time in the wireless communication domain, we exploit the potential of deep neural networks in conjunction with multi-task learning (MTL) framework to simultaneously learn modulation and signal classification tasks. The proposed MTL architecture benefits from the mutual relation between the two tasks in improving the classification accuracy as well as the learning efficiency with a lightweight neural network model. Additionally, we consider the problem of heterogeneous wireless signals such as radar an...
The year 2019 witnessed the rollout of the 5G standard, which promises to offer significant data ... more The year 2019 witnessed the rollout of the 5G standard, which promises to offer significant data rate improvement over 4G. While 5G is still in its infancy, there has been an increased shift in the research community for communication technologies beyond 5G. The recent emergence of machine learning approaches for enhancing wireless communications and empowering them with much-desired intelligence holds immense potential for redefining wireless communication for 6G. The evolving communication systems will be bottlenecked in terms of latency, throughput, and reliability by the underlying signal processing at the physical layer. In this position paper, we motivate the need to redesign iterative signal processing algorithms by leveraging deep unfolding techniques to fulfill the physical layer requirements for 6G networks. To this end, we begin by presenting the service requirements and the key challenges posed by the envisioned 6G communication architecture. We outline the deficiencies ...
The year 2019 witnessed the rollout of the 5G standard, which promises to offer significant data ... more The year 2019 witnessed the rollout of the 5G standard, which promises to offer significant data rate improvement over 4G. While 5G is still in its infancy, there has been an increased shift in the research community for communication technologies beyond 5G. The recent emergence of machine learning approaches for enhancing wireless communications and empowering them with much-desired intelligence holds immense potential for redefining wireless communication for 6G. The evolving communication systems will be bottlenecked in terms of latency, throughput, and reliability by the underlying signal processing at the physical layer. In this position paper, we motivate the need to redesign iterative signal processing algorithms by leveraging deep unfolding techniques to fulfill the physical layer requirements for 6G networks. To this end, we begin by presenting the service requirements and the key challenges posed by the envisioned 6G communication architecture. We outline the deficiencies ...
Automatic modulation classification (AMC) is a key component of intelligent communication systems... more Automatic modulation classification (AMC) is a key component of intelligent communication systems used in various military and cognitive radio applications. In AMC, it is desired to increase the number of different modulation formats that can be classified, reduce the computational complexity of classification, and improve the robustness and accuracy of the classifier. Generally, AMC techniques are classified into feature based (FB) and likelihood based (LB) classifiers. In this paper, we propose a novel hierarchical hybrid automatic modulation classifier (HH-AMC) that employs both feature based and likelihood based classifiers to improve performance and reduce complexity. As another major contribution of this paper, we implement and evaluate the performance of HH-AMC over-the-air (OTA) using software defined radios (SDRs) to demonstrate the feasibility of the proposed scheme in practice. Experimental evaluation shows high probability of correct classification (P cc) for both linear and non-linear modulation formats including BPSK, QPSK, 8-PSK, 16-QAM, 32-QAM, CPFSK, GFSK and GMSK under lab conditions.
Visible Light Ad Hoc Networks (LANETs) have the potential to offer capabilities to satisfy growin... more Visible Light Ad Hoc Networks (LANETs) have the potential to offer capabilities to satisfy growing industrial and military requirements, including low-latency, high bandwidth communication under high network density and jamming conditions. The challenges imposed by hidden nodes, deafness and blockage are unique to LANET and influence the network differently from traditional Mobile Ad Hoc Networks (MANETs) due to directionality and Line of Sight (LOS) requirements. Therefore, networking protocols have to be redesigned with careful consideration of these challenges. As an initial step in this direction, this paper proposes a utility based opportunistic three-way handshake mechanism to negotiate medium access. First, a node chooses the optimal transmission sector, i.e., the "direction" that maximizes the probability of establishing a link even when some of the neighbors are affected by blockage or deafness. The utility function is designed to favor the establishment of full-duplex communication links. The full-duplex transmission or busy tone along with power control employed by the proposed Medium Access Control (MAC) protocol is aimed at mitigating the hidden node problem. All these factors contribute towards maximizing the throughput of LANET. Performance evaluation studies through extensive simulations show up to 61% increase in throughput and significant improvement in the number of full-duplex links established with respect to Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA).
The design and implementation of a novel distributed deadline-based routing and spectrum allocati... more The design and implementation of a novel distributed deadline-based routing and spectrum allocation algorithm for tactical ad-hoc networks is reported in this article. Different traffic classes including text, voice, surveillance video, threat alert among others need to be handled by these networks. Each of these traffic classes have different quality of service (QoS) based deadline requirements. Additionally, these networks are characterized by dynamic channel and traffic conditions that vary with time and location. Even under these conditions, it is critical to receive packets before the deadline expires to make rapid decisions in the battlefield. Therefore, a tactical ad-hoc network should be able to adapt to these requirements and maximize the number of packets delivered to the destination within the specified deadline. A distributed deadline-based routing and spectrum allocation algorithm is designed to maximize the utilization of the available resources and ensure delivery of packets within the deadline constraints. To this end, a weighted virtual queue (VQ) that is used to construct the network utility function is defined. Accordingly, the optimal session, next hop, transmit power and frequency is determined by the distributed algorithm to ensure efficient utilization of the available resources. Hence, maximizing the delivery of packets to the intended destination within the specified deadline. The 49 node simulation shows up to 35 % improvement in effective throughput and 26 % improvement in reliability as compared to joint ROuting and Spectrum Allocation algorithm (ROSA), which does not adapt according to the deadline requirements of the data flowing through the network. As a secondary objective, this work advances the state of the art of the experimental cross layer framework to address the challenges involved in having such cross layer algorithms implemented on a testbed. The required flexibility to change the transmission parameters on-the-fly is provided by the proposed framework. The network is designed to enable the data exchange between neighbors using custom designed control packets (which might be different for different algorithms) since this information is critical for nodes to perform optimization. Cross layer optimization is achieved by means of data management and control entities that enable information exchange between layers. The practicality of the proposed solution was proven by having the novel algorithm implemented on a five-node software defined radio testbed which leverages the proposed cross-layer framework. In contrast to ROSA, the proposed algorithm demonstrated up to 17% improvement in terms of throughput and reliability. The performance improvement achieved is expected to increase on a larger network deployment.
The concept of cross-layer optimization has been around for several years now. The primary goal o... more The concept of cross-layer optimization has been around for several years now. The primary goal of the cross-layer approach was to liberate the strict boundary between the layers of the traditional OSI protocol stack. This is to enable information flow between layers which then can be leveraged to optimize the network’s performance across the layers. This concept has been of keen interest for tactical application as there is an overwhelming requirement to operate in a challenging and dynamic environment. The advent of software defined radios (SDR) accelerated the growth of this domain due to the added flexibility provided by SDRs. Even with the immense interest and progress in this area of research, there has been a gaping abyss between solutions designed in theory and ones deployed in practice. To the best of our knowledge, this is the first time in literature, an embedded SDR has been leveraged to successfully design a cross-layer optimized transceiver that provides high throughpu...
2020 29th International Conference on Computer Communications and Networks (ICCCN), 2020
Multiple-input multiple-output (MIMO) systems find immense potential and applicability in the lon... more Multiple-input multiple-output (MIMO) systems find immense potential and applicability in the long term evolution (LTE), 5G, Internet of Things (IoT), vehicular ad hoc networks (VANETs), and tactical communication systems. Jamming poses significant communication hindrance as well as security risks to the wireless communication systems. The achievable rate and reliability are the two most compromised aspects of a wireless link under such severe jamming. Owing to the high capacity and reliability of MIMO systems, they are increasingly used in tactical and critical applications. Therefore, it becomes essential to assess and enhance their sustenance under hostile jamming scenarios. To this end, we address the rate and reliability requirements of a MIMO OFDM system and propose a novel rate-reliability beamformer transceiver design for highly reliable and spectrally efficient operation under the most detrimental jamming attacks. We consider the disguised all band and multiband jamming whe...
2020 14th International Conference on Signal Processing and Communication Systems (ICSPCS), 2020
Intentional and unintentional interferences collectively referred to as Radio Frequency Interfere... more Intentional and unintentional interferences collectively referred to as Radio Frequency Interference (RFI) resuit in severe security threat to the public safety, first responder emergency rescue and military missions. Such RFI if not detected and localized can disrupt the wireless communication which forms the backbone of first responder and military operations. The prime objective of this work was to design and prototype a RFI detection and localization device, Jam-Guard that significantly outperforms traditional approaches in real-life deployment yet be computationally feasible to be developed as a low SWaC (size, weight, and cost) device. The proposed device employs a unique combination of robust parallel detection algorithms based on Kurtosis and FRactional Fourier Transform (FRFT) with Golden Section Search algorithm to rapidly detect RFI that affects critical communication signais. The localization scheme is designed to leverage the FRFT output from the detection phase to ease...
Space Time Block Codes (STBCs) from orthogonal designs have attracted significant interest in rec... more Space Time Block Codes (STBCs) from orthogonal designs have attracted significant interest in recent years. However, with the growing demand for higher capacity schemes, the multiantenna transmission techniques must support and achieve higher symbol transmission rates. In this article, we focus on three and four transmit antenna schemes. For over two decades, STBC schemes for three and four transmit antennas that achieve a very high symbol transmission rate while being orthogonal, fully diverse, delay-efficient, and with very low decoding complexity have not been achieved. The schemes proposed so far trades off orthogonality, delay, diversity, or decoding complexity while achieving rate or vice-versa. This work is first of its kind to solve this problem while fulfilling all the desired properties. In this work, we carefully study the various aspects that must be considered in designing higher symbol transmission rate STBCs. The proposed designs, hereby referred to as, Jagannath sche...
2019 IEEE Cognitive Communications for Aerospace Applications Workshop (CCAAW), 2019
In this position paper, the authors argue the need for a novel framework that provides flexibilit... more In this position paper, the authors argue the need for a novel framework that provides flexibility, autonomy and optimizes the use of scarce resources to ensure reliable communication during next-generation space missions. To this end, the authors present the shortcomings of existing space architectures and the challenges in realizing adaptive autonomous space-networking. In this regard, the authors aim to jointly exploit the immense capabilities of deep reinforcement learning (DRL) and cross-layer optimization by proposing an artificial intelligence-based cognitive cross-layer decision engine to bolster next-generation space missions. The presented software-defined cognitive cross-layer decision engine is designed for the resource-constrained Internet-of-Space-Things. The framework is designed to be flexible to accommodate varying (with time and location) requirements of multiple space missions such as reliability, throughput, delay, energy-efficiency among others. In this work, th...
This paper reports on challenges and opportunities associated with the development of an electroe... more This paper reports on challenges and opportunities associated with the development of an electroencephalogram (EEG) based personalized device for monitoring of brain activities pertaining large scale neural dynamics in the observed and providing relevant feedback to the observer. The envisioned device interprets signals and categorizes them on classes of typical responses. This could enable a speechless interaction between an observer and a participant wearing the device. This framework is different from the brain-computer-interface (BCI) framework as it focuses on indicators relevant to the human observer, brain-observer-indicator (BOI). Sensors detect resting states of the brain with associated patterns, synchrony between regions, and spectral changes in response to a cognitive event. A cognitive event results in notable changes in the associated patterns of electrical potentials. Recognition of these patterns has a broad application base, if the pattern-activity mechanism is char...
This paper introduces innovative technology development that will improve performance of next-gen... more This paper introduces innovative technology development that will improve performance of next-generation cognitive wireless networking among space, air, and ground assets. The paper describes methods to develop a system where cognitive users transmit wideband spread-spectrum signals that are designed to adaptively avoid the interference dynamics of the available spectrum at the receiver. These technological advances can achieve improvement in network throughput, delay, and reliability. Theoretical performance expectations are given. The theoretical approach is translated to the construction of specific software techniques and their implementation within the cross-layer wireless communications architecture. The hardware/software testbed that simulates a dynamic Ad Hoc Software Defined Radio (SDR) network is described, and a series of tests to measure the value of the optimization techniques is given. Preliminary test results and the total expected performance improvements are shown. ...
In this position paper, we discuss the critical need for integrating zero trust (ZT) principles i... more In this position paper, we discuss the critical need for integrating zero trust (ZT) principles into next-generation communication networks (5G/6G) for both tactical and commercial applications. We highlight the challenges and introduce the concept of an intelligent zero trust architecture (i-ZTA) as a security framework in 5G/6G networks with untrusted components. While network virtualization, software-defined networking (SDN), and service-based architectures (SBA) are key enablers of 5G networks, operating in an untrusted environment has also become a key feature of the networks. Further, seamless connectivity to a high volume of devices in multi-radio access technology (RAT) has broadened the attack surface on information infrastructure. Network assurance in a dynamic untrusted environment calls for revolutionary architectures beyond existing static security frameworks. This paper presents the architectural design of an i-ZTA upon which modern artificial intelligence (AI) algorit...
Smart grids are vulnerable to cyber-attacks. This paper proposes a game-theoretic approach to eva... more Smart grids are vulnerable to cyber-attacks. This paper proposes a game-theoretic approach to evaluate the variations caused by an attacker on the power measurements. Adversaries can gain financial benefits through the manipulation of the meters of smart grids. On the other hand, there is a defender that tries to maintain the accuracy of the meters. A zero-sum game is used to model the interactions between the attacker and defender. In this paper, two different defenders are used and the effectiveness of each defender in different scenarios is evaluated. Multi-layer perceptrons (MLPs) and traditional state estimators are the two defenders that are studied in this paper. The utility of the defender is also investigated in adversary-aware and adversary-unaware situations. Our simulations suggest that the utility which is gained by the adversary drops significantly when the MLP is used as the defender. It will be shown that the utility of the defender is variant in different scenarios,...
Wireless signal recognition is becoming increasingly more significant for spectrum monitoring, sp... more Wireless signal recognition is becoming increasingly more significant for spectrum monitoring, spectrum management, and secure communications. Consequently, it will become a key enabler with the emerging fifth-generation (5G) and beyond 5G communications, Internet of Things networks, among others. State-of-the-art studies in wireless signal recognition have only focused on a single task which in many cases is insufficient information for a system to act on. In this work, for the first time in the wireless communication domain, we exploit the potential of deep neural networks in conjunction with multi-task learning (MTL) framework to simultaneously learn modulation and signal classification tasks. The proposed MTL architecture benefits from the mutual relation between the two tasks in improving the classification accuracy as well as the learning efficiency with a lightweight neural network model. Additionally, we consider the problem of heterogeneous wireless signals such as radar an...
The year 2019 witnessed the rollout of the 5G standard, which promises to offer significant data ... more The year 2019 witnessed the rollout of the 5G standard, which promises to offer significant data rate improvement over 4G. While 5G is still in its infancy, there has been an increased shift in the research community for communication technologies beyond 5G. The recent emergence of machine learning approaches for enhancing wireless communications and empowering them with much-desired intelligence holds immense potential for redefining wireless communication for 6G. The evolving communication systems will be bottlenecked in terms of latency, throughput, and reliability by the underlying signal processing at the physical layer. In this position paper, we motivate the need to redesign iterative signal processing algorithms by leveraging deep unfolding techniques to fulfill the physical layer requirements for 6G networks. To this end, we begin by presenting the service requirements and the key challenges posed by the envisioned 6G communication architecture. We outline the deficiencies ...
The year 2019 witnessed the rollout of the 5G standard, which promises to offer significant data ... more The year 2019 witnessed the rollout of the 5G standard, which promises to offer significant data rate improvement over 4G. While 5G is still in its infancy, there has been an increased shift in the research community for communication technologies beyond 5G. The recent emergence of machine learning approaches for enhancing wireless communications and empowering them with much-desired intelligence holds immense potential for redefining wireless communication for 6G. The evolving communication systems will be bottlenecked in terms of latency, throughput, and reliability by the underlying signal processing at the physical layer. In this position paper, we motivate the need to redesign iterative signal processing algorithms by leveraging deep unfolding techniques to fulfill the physical layer requirements for 6G networks. To this end, we begin by presenting the service requirements and the key challenges posed by the envisioned 6G communication architecture. We outline the deficiencies ...
Automatic modulation classification (AMC) is a key component of intelligent communication systems... more Automatic modulation classification (AMC) is a key component of intelligent communication systems used in various military and cognitive radio applications. In AMC, it is desired to increase the number of different modulation formats that can be classified, reduce the computational complexity of classification, and improve the robustness and accuracy of the classifier. Generally, AMC techniques are classified into feature based (FB) and likelihood based (LB) classifiers. In this paper, we propose a novel hierarchical hybrid automatic modulation classifier (HH-AMC) that employs both feature based and likelihood based classifiers to improve performance and reduce complexity. As another major contribution of this paper, we implement and evaluate the performance of HH-AMC over-the-air (OTA) using software defined radios (SDRs) to demonstrate the feasibility of the proposed scheme in practice. Experimental evaluation shows high probability of correct classification (P cc) for both linear and non-linear modulation formats including BPSK, QPSK, 8-PSK, 16-QAM, 32-QAM, CPFSK, GFSK and GMSK under lab conditions.
Visible Light Ad Hoc Networks (LANETs) have the potential to offer capabilities to satisfy growin... more Visible Light Ad Hoc Networks (LANETs) have the potential to offer capabilities to satisfy growing industrial and military requirements, including low-latency, high bandwidth communication under high network density and jamming conditions. The challenges imposed by hidden nodes, deafness and blockage are unique to LANET and influence the network differently from traditional Mobile Ad Hoc Networks (MANETs) due to directionality and Line of Sight (LOS) requirements. Therefore, networking protocols have to be redesigned with careful consideration of these challenges. As an initial step in this direction, this paper proposes a utility based opportunistic three-way handshake mechanism to negotiate medium access. First, a node chooses the optimal transmission sector, i.e., the "direction" that maximizes the probability of establishing a link even when some of the neighbors are affected by blockage or deafness. The utility function is designed to favor the establishment of full-duplex communication links. The full-duplex transmission or busy tone along with power control employed by the proposed Medium Access Control (MAC) protocol is aimed at mitigating the hidden node problem. All these factors contribute towards maximizing the throughput of LANET. Performance evaluation studies through extensive simulations show up to 61% increase in throughput and significant improvement in the number of full-duplex links established with respect to Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA).
The design and implementation of a novel distributed deadline-based routing and spectrum allocati... more The design and implementation of a novel distributed deadline-based routing and spectrum allocation algorithm for tactical ad-hoc networks is reported in this article. Different traffic classes including text, voice, surveillance video, threat alert among others need to be handled by these networks. Each of these traffic classes have different quality of service (QoS) based deadline requirements. Additionally, these networks are characterized by dynamic channel and traffic conditions that vary with time and location. Even under these conditions, it is critical to receive packets before the deadline expires to make rapid decisions in the battlefield. Therefore, a tactical ad-hoc network should be able to adapt to these requirements and maximize the number of packets delivered to the destination within the specified deadline. A distributed deadline-based routing and spectrum allocation algorithm is designed to maximize the utilization of the available resources and ensure delivery of packets within the deadline constraints. To this end, a weighted virtual queue (VQ) that is used to construct the network utility function is defined. Accordingly, the optimal session, next hop, transmit power and frequency is determined by the distributed algorithm to ensure efficient utilization of the available resources. Hence, maximizing the delivery of packets to the intended destination within the specified deadline. The 49 node simulation shows up to 35 % improvement in effective throughput and 26 % improvement in reliability as compared to joint ROuting and Spectrum Allocation algorithm (ROSA), which does not adapt according to the deadline requirements of the data flowing through the network. As a secondary objective, this work advances the state of the art of the experimental cross layer framework to address the challenges involved in having such cross layer algorithms implemented on a testbed. The required flexibility to change the transmission parameters on-the-fly is provided by the proposed framework. The network is designed to enable the data exchange between neighbors using custom designed control packets (which might be different for different algorithms) since this information is critical for nodes to perform optimization. Cross layer optimization is achieved by means of data management and control entities that enable information exchange between layers. The practicality of the proposed solution was proven by having the novel algorithm implemented on a five-node software defined radio testbed which leverages the proposed cross-layer framework. In contrast to ROSA, the proposed algorithm demonstrated up to 17% improvement in terms of throughput and reliability. The performance improvement achieved is expected to increase on a larger network deployment.
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Papers by Jithin Jagannath