Sunil Kumar

San Diego State University | SDSU · Department of Electrical and Computer Engineering

The medium access control (MAC) design in mobile networks with directional antennas is challenging due to the difficulty of defining the exact RF interference range between two neighboring directional links and the frequent changes of interference range due to node mobility. This research targets directional data reception (Rx) and transmission (Tx...

By applying a simple shortest/minimum-cost routing algorithm, the mobile ad-hoc network (MANET) with heavy data transmissions may be easily congested if multiple routing paths meet at the same relay node. A path may be unable to provide high throughput since some of its path nodes are helping other paths to forward the heavy traffic. Therefore, tho...

UAV networks consisting of reduced size, weight, and power (low SWaP) fixed-wing UAVs are used for civilian and military applications such as search and rescue, surveillance, and tracking. To carry out these operations efficiently, there is a need to develop scalable, decentralized autonomous UAV network architectures with high network connectivity...

A directional airborne network consisting of nodes equipped with multibeam antennas is considered. These nodes use the frequency division duplex mode of communication. This allows formation of multiple routes between a pair of source and destination nodes, where every forward and reverse route completely overlaps. Each of these routes supports the...

An autonomous airborne network (AN) consists of multiple unmanned aerial vehicles (UAVs), which can self-configure to provide seamless, low-cost and secure connectivity. AN is preferred for applications in civilian and military sectors because it can improve the network reliability and fault tolerance, reduce mission completion time through collabo...

The Terahertz (THz) link provides over 100 Gbps of data transmission rate. However, it is extremely vulnerable to obstacles and requires very narrow (highly directional) beams for highly focused energy radiation. The main task of THz medium access control (MAC) protocol is not channel access collision avoidance; instead, it is to coordinate all the...

Autonomous and decentralized UAV networks are used in many applications, including disaster management, environment monitoring and surveillance. The performance of the routing protocols in these networks drops significantly due to frequent route breaks and traffic congestion at high node speeds. This is partly because the routing metrics used in ma...

A node equipped with a multi-beam antenna can achieve a throughput of up to m times as compared to a single-beam antenna, by simultaneously communicating on its m non-interfering beams. However, the existing multi-beam medium access control (MAC) schemes can achieve concurrent data communication only when the transmitter nodes are locally synchroni...

This paper focuses on the congestion control issues of Unmanned Aerial Vehicle (UAV) Swarm Networks (USNs). In a USN, many network factors can cause segment loss, such as dynamic swarming, high mobility, etc. With traditional transport layer protocols such as Transmission Control Protocol (TCP), these losses are interpreted as congestion events and...

Recent advances in antenna technology have made the design of multi-beam antennas (MBA) feasible. Compared to an omni-directional or a single beam directional antenna, an MBA equipped node can achieve a throughput of up to m times, by simultaneously communicating on its m non-interfering beams. As a result, a few multi-beam directional medium acces...

The unmanned aerial vehicle (UAV) network is a special type of mobile ad hoc network (MANET). ¹There are two types of UAV swarm communications: Communications within a swarm (i.e. intra-swarm) and communication between different swarms (i.e. inter-swarm). This paper proposes the concept of bridge routing to establish the route(s) for efficient inte...

A challenging issue for a three-dimensional (3D) unmanned aerial vehicle (UAV) network is addressed in this paper - how do we efficiently establish and maintain one or multiple routes among swarm regions (i.e., groups of UAVs), during the dynamic swarming process? Inspired by the human nervous system which can efficiently send brain signals to...

Time division multiple access (TDMA) based medium access control (MAC) schemes are widely used for communication among directional nodes since they can provide a conflict-free transmission schedule. However, the existing directional TDMA schemes introduce significant overhead and delay, and cannot adapt in real-time to topology changes in a directi...

A swarm of unmanned aerial vehicles (UAVs) requires the transmission of mission-related data across the network. The resource constraints and dynamic nature of the swarm bring critical challenges to the design of UAV routing protocols. Most of the conventional ad hoc routing schemes are not intelligent and cannot adapt to the dynamic nature of UAV...

The use of frequency division duplex (FDD) communication in a multihop wireless network partitions the nodes in two operating modes. Since the FDD nodes of the same mode cannot communicate with each other, it can limit the node connectivity and also lead to network partitioning. In this paper, a novel, distributed, low-complexity mode reassignment...

This research targets the robust routing protocols in airborne networks (ANs). Particularly, we target the AN which is equipped with the latest antenna technology, called Multi-Beam Directional Antenna (MBDA) [1]. MBDA allows the simultaneously packet delivery in multiple directions without RF interference between directions/beams. We have found th...

In this paper, we study the communication-oriented unmanned air vehicle (UAV) placement issue in a typical manned-and-unmanned (MUM) airborne network. The MUM network consists of a few powerful aircraft nodes in the higher layer and high-density UAVs in the lower layer. While the aircraft network is relatively stable, the UAVs can form different sw...

The emergence of multi-beam directional antennas (MBDAs) has paved the way for fast and high-throughput data communications by providing concurrent multi-directional transmissions. However, the existing routing protocols are not capable of utilizing the advantages of MBDAs. In this paper, we have developed a new routing scheme, called as the volcan...

We consider a decentralized, multihop wireless network consisting of frequency division duplex (FDD) nodes, which use separate frequency bands for transmission and reception. The use of FDD communication in a multihop wireless network partitions the nodes in two operating modes (or genders), depending on the frequency bands used for the transmissio...

A heterogeneous medium access control (MAC) scheme (with both scheduled and random communications) is proposed for airborne networks. These networks have a hierarchical topology with a small number of powerful aircraft nodes with multi-beam antennas and long-distance links at the higherlevel, and high-density UAV nodes with single-beam directional...

By using the multi-beam smart antennas (MBSAs), the nodes can form a high-throughput wireless mesh network (WMN) with concurrent packet delivery in multiple directions. A novel medium access control (MAC) scheme is designed for multi-beam airborne mesh networks, in this paper. It has the following two features: (1) IEEE 802.11-compatible, interfere...

In this research we target the routing design in a directional hierarchical airborne network. Such a network has the following 2 main features: (1) Two-level architecture: The high level is a sparse wireless network with long-distance links and high-rate communications. It also has a commander node. The lower level is a high-density network with sh...

The Multi-Path, Multi-Hop (MPMH) communications have been extensively used in wireless network. It is especially suitable to big data transmissions due to its high throughput. To provide congestion and end-to-end reliability control, two types of transport layer protocols have been proposed in the literature: the TCP-based protocols and the rateles...

Use of multi-beam directional antennas (MBDAs) allows a node to simultaneously communicate in multiple directions on its different beams, which can significantly improve the data throughput compared with omni-directional or singlebeam directional antennas. However, conventional multi-hop wireless routing protocols cannot effectively exploit the ben...

A real-time cognitive radio network (CRN) testbed is implemented by using the universal software radio peripheral (USRP) and GNU Radio to demonstrate the use of reinforcement learning and transfer learning schemes for spectrum handoff decisions. By considering the channel status (idle or occupied) and channel condition (in terms of packet error rat...

In the software defined networking (SDN)-based wireless mesh network (WMN) architecture (SD-WMN), the network is monitored and managed in a centralized manner. Although the use of SDN simplifies the WMN management, it is still not clear whether the SDN architecture, which was originally designed for wired links, can effectively handle the dynamic t...

The frequency-division duplex (FDD) nodes use two separate frequency bands (separated by a guard band) for transmission and reception, thus enabling the full-duplex (FD) communication. On the other hand, the use of directional FDD nodes in multihop wireless network offers the advantages of larger transmission range, better link reliability, and spa...

A novel spectrum handoff scheme, called Feature Stacking (FEAST), is proposed to achieve the optimal “channel + beam” handoff (CBH) control in cognitive radio networks (CRNs) with multi-beam smart antennas (MBSAs). FEAST uses the online supervised learning based on the support vector machine (SVM) to maximize the long-term quality of experience (Qo...

The frequency-division duplex (FDD) nodes use two separate frequency bands (separated by a guard band) for transmission and reception, thus enabling the full-duplex (FD) communication. On the other hand, the use of directional FDD nodes in multihop wireless network offers the advantages of larger transmission range, better link reliability, and spa...

Background: Quantitative structure-activity relationship (QSAR) models can be used as a predictive tool for virtual screening of chemical libraries to identify novel drug candidates. The aims of this paper were to report the results of a study performed for descriptor selection, QSAR model development, and virtual screening for identifying novel H...

In recent years, Open Flow [1] is becoming a popular network architecture. As more and more users starts to join the conventional Internet, the drawbacks of the conventional networks are now gradually appearing. OpenFlow network provides us a brand new sight to the development of networks. This architecture separates the control plane and data plan...

We propose a novel spectrum decision scheme (i.e., channel selection and handoff) for wireless mesh networks (WMN) which use multiple channels and nodes equipped with multi-beam directional antennas. Our scheme has the following features: (i) It performs spectrum decision by considering various WMN parameters, including the channel quality, beam or...

An optimal spectrum handoff scheme for cognitive radio networks (CRNs) is presented in this paper. This scheme has two novel features: 1) Hybrid rule-based priority queuing model: To overcome the limitations of preemptive resume priority and nonpreemptive resume priority (PRP/NPRP) queuing models, a hybrid queuing model with discretion rule is prop...

Demand response offers financial incentives for consumers who are willing to relocate some or all of their electricity demand during peak periods. In price based demand response programs, utility companies can use energy pricing as an effective control signal to reschedule electricity demand from peak hours to off-peak periods. A real-time (RT) res...

We propose the use of the Least Absolute Shrinkage and Selection Operator (LASSO) regression method in order to predict the Cumulative Mean Squared Error (CMSE), incurred by the loss of individual slices in video transmission. We extract a number of quality-relevant features from the H.264/AVC video sequences, which are given as input to the LASSO....

Video transmission over wireless channels is affected by channel-induced packet losses. Distortion due to channel errors can be alleviated by applying forward error correction. Aggregating H.264/AVC slices to form video packets with sizes adapted to their importance can also improve transmission reliability. Larger packets are more likely to be in...

The cumulative mean squared error (CMSE) is a widely used measure of distortion introduced by a slice loss. We propose a low-complexity and low-delay generalized linear model for predicting CMSE contributed by the loss of individual H.264/AVC encoded video slices. We train the model over a video database by using a combination of video factors that...

Mobility and spectrum change of the cognitive radio networks (CRNs), make the traffic information exchange among the secondary users (SUs) a high-overhead task. In order to quickly estimate the queuing delay in the multimedia over CRN applications without exchanging traffic information among SUs, we are the first group to propose the use of Dirichl...

Enabling the spectrum handoff for multimedia applications in cognitive radio networks (CRNs) is challenging, due to multiple interruptions from primary users (PUs), contentions among secondary users (SUs), and heterogenous Quality-of-Experience (QoE) requirements. In this paper, we propose a learning-based and QoE-driven spectrum handoff scheme to...

The unequal error protection (UEP) has shown promising results for transmitting video over error-prone wireless channels. In this paper, we investigate the cross-layer design of forward error correction (FEC) schemes by using the UEP Raptor codes at the application layer (AL) and UEP rate compatible punctured convolutional (RCPC) codes at physical...

In this paper, we propose a mixed preemptive and non-preemptive resume priority (PRP/NPRP) M/G/1 queueing model for the modeling of the traffic in Cognitive Radio (CR) Networks with prioritized transmissions. A traffic-adaptive spectrum handoff scheme is then developed based on the proposed queueing model for delay sensitive applications. This spec...

Cognitive Radio (CR) can efficiently utilize the licensed wideband spectrum whenever the primary users (PUs) are absent. Spectrum sensing is the first step and an important function to fulfill the CR system. A cyclostationary feature detector can robustly detect the PU's modulated signals even under strong interferences. However this detector needs...

Forward error correction (FEC) codes that can provide unequal error protection (UEP) have been used recently for video transmission over wireless channels. These video transmission schemes may also benefit from the use of FEC codes both at the application layer (AL) and the physical layer (PL). However, the interaction and optimal setup of UEP FEC...

Demand Response (DR) and Time-of-Use (TOU) pricing refer to programs which offer incentives to customers who curtail their energy use during times of peak demand. In this paper, we propose an integrated solution to predict and re-engineer the electricity demand (e.g., peak load reduction and shift) in a locality at a given day/time. The system pres...

The classification of image-objects is usually done using parametric statistical measures of central tendency and/or dispersion (e.g., mean or standard deviation). The objectives of this study were to analyze digital number histograms of image objects and evaluate classifications measures exploiting characteristic signatures of such histograms. Two...

As the world energy crisis continues to burden our natural resources, it is imperative that current technologies be employed to make energy usage more efficient. In this paper, an intelligent residential home energy management system is discussed. A Master Energy Controller was developed to forecast future power demand based on user's life style an...

Demand Response (DR) and Time-of-Use (TOU) pricing refer to programs offering incentives to customers who reduce their energy use during times of peak demand. A demand response system coordinates the demand and supply between the energy provider and the customer. In this study, a turn-key solution is developed to offer demand response services for...

We investigate the rate-compatible punctured convolutional (RCPC) codes concatenated with hierarchical QAM for designing a cross-layer unequal error protection scheme for H.264 coded sequences. We first divide the H.264 encoded video slices into three priority classes based on their relative importance. We investigate the system constraints and pro...

Node mobility in mobile ad hoc networks (MANETs) causes frequent route breakages and intermittent link stability. In this paper, we introduce a robust routing scheme, known as ad hoc on-demand multipath distance vector with dynamic path update (AOMDV-DPU), for delay-sensitive data transmission over MANET. The proposed scheme improves the AOMDV sche...

Recent developments in cognitive radio networks have enabled intelligent spectrum management, dynamic message traffic patterns, and adaptive platform configuration. However, as these developments extend from the software-defined radio, there are numerous research questions that require further analysis over the user, network, and application qualit...

In cognitive radio networks, spectrum sensing and channel assignment are very important. Each user senses the channels and sends the results to a cluster head (CH) to make a decision about the channels by combining the results from different users. Moreover, the CH can assign the channels to the secondary users based on their requirements and prior...

With the need to provide efficient means for improving energy consumption comes the need to apply the latest technologies for home energy management as well as the necessity to include the residential customer in the energy usage decision loop. Thus, the user should have as much information about past energy profiles, scheduling scenarios, and pric...

The transmission over error-prone networks of block-based coded images may results in the lost of the several images blocks, degrading drastically the visual quality of images. Consequently, if retransmission is not feasible, then applications of error concealment techniques are required to reduce this degradation caused mainly by the missing infor...

We propose a low complexity Generalized Linear Model (GLM) for prioritizing slices during real-time H.264/AVC compressed video streaming. We train the GLM over a video database to predict the Cumulative Mean Square Error (CMSE) corresponding to individual slice losses by using a combination of efficient video parameters which can be easily extracte...

The quality of H.264/AVC compressed video delivery over wireless channels is affected by packet losses. Aggregating H.264/AVC slices to form video packets with sizes adaptive to their importance can improve transmission reliability. Larger packets are more likely to be in error but smaller packets cause more overhead. A second method is assigning s...

A hybrid differential evolution-binary particle swarm optimization (DE-BPSO) algorithm is proposed as a feature selection algorithm in the development of quantitative structure-activity relationship (QSAR) models. DE is used to evolve the velocities of the particle swarm from which a series of rules are used to determine the discrete values of the...

A comparative analysis of three important shape analysis techniques viz. real spherical harmonic (RSH) coefficient, shape signatures based on ray-tracing, and multi-resolution attributed contour tree (MACT) is performed to understand their strengths and weaknesses in terms of their shape description power and computational ability. The analysis is...

We introduce a cross-layer priority-aware packet fragmentation scheme at the MAC layer to enhance the quality of pre-encoded H.264/AVC compressed bitstreams over bit-rate limited error-prone links in wireless networks. The H.264 slices are classified in four priorities at the encoder based on their cumulative mean square error (CMSE) contribution t...

The human immunodeficiency virus type 1 (HIV-1) integrase is an emerging target for novel antiviral drugs. Quantitative structure-activity relationship (QSAR) models for HIV-1 integrase inhibitors have been developed to understand the protein-ligand interactions to aid in the design of more effective analogs. This review paper presents a comprehens...

In this paper, we present a robust transmission scheme for MPEG-4 AAC encoded audio data over fading wireless channels using Unequal Error Protection based on adaptive modulation and forward error correcting (FEC) codes. The encoded audio data is divided into three error sensitivity categories and a suitable combination of FEC and modulation order...

Demand response (DR) can be defined as change in electric usage by end-use customers from their normal consumption patterns in response to change in the price of electricity over time. Demand Response also refers to incentive payments designed to induce lower electricity use at times of high wholesale market prices. Time-of-use (TOU) power pricing...

We introduce a cross-layer priority-aware packet fragmentation scheme to enhance the quality of H.264 compressed bitstreams over bit-rate limited error-prone links in packet networks. The H.264 slices are prioritized in the encoder based on their cumulative mean square error (CMSE) contribution towards the received video quality. Specifically we de...

Recently, multimedia transmission over cognitive radio networks (CRNs) becomes an important topic due to the CR's capability of using unoccupied spectrum for data transmis- sion. Conventional work has focused on typical quality-of-service (QoS) factors such as radio link reliability, maximum tolerable communication delay, and spectral efficiency. H...

In high-mobility cognitive radio networks (CRNs), the fast topology changes increase the complexity of the routing scheme. In this paper, we propose a novel CRN routing scheme that considers the path stability and node capacity. First, a realistic mobility model is proposed to describe the movement of highly mobile airborne nodes [e.g., unmanned ae...

This paper proposes an optimal packet size search method for multimedia transmission over multi-channel link in multi-class cognitive radio networks. Since the transmission power is limited for users, optimal packet size and corresponding power allocation is needed to maximize expected utility function. The performance is evaluated through the comp...

In order to create multimedia products such as smart-phones, media players, gaming consoles among others, developers need to optimize the low-level code. Currently, this code is written mostly in assembly language and must be rewritten for each different hardware platform. For this reason, the development of media infrastructure is very expensive,...

Using a shape analysis technique, a Dataset of 79 (19 wild-type and 60 mutated) HIV-1 protease crystal structures was analyzed for the shape changes in their binding pockets. The structures are reported with different bound inhibitors and consist of a variety of mutations. Several 3D-shape descriptors based on the volumetric shape function are calc...

In this paper, it is proposed to design and implement a physical layer Unequal Error Protection (UEP) scheme based on convolutional codes and asymmetric 8PSK modulation. This scheme is combined with the UEP schemes at the application layer that is, multi-level unequal importance of compressed H.264/AVC video data. The proposed scheme takes the prio...

The demand for electricity is at its peak during the summer months in general and during hot summer days in particular. The increased use of electrical appliances and HVAC systems in residential homes plays a considerable role in this demand. However, usage of these appliances, can be done in a more cost efficient manner through scheduling, avoidin...

Mutations that arise in HIV-1 protease after exposure to various HIV-1 protease inhibitors have proved to be a difficult aspect in the treatment of HIV. Mutations in the binding pocket of the protease can prevent the protease inhibitor from binding to the protein effectively. In the present study, the crystal structures of 68 HIV-1 proteases comple...

Compressed video data is very sensitive to channel-induced errors and network losses. Most conventional unequal error protection techniques involve forward error correction codes of different rates or asymmetric signal constellations for data of different priorities. It is yet unknown if combining the above two techniques can further improve perfor...

The prediction of biological activity of a chemical compound from its structural features plays an important role in drug design. In this paper, we discuss the quantitative structure activity relationship (QSAR) prediction models developed on a dataset of 170 HIV protease enzyme inhibitors. Various chemical descriptors that encode hydrophobic, topo...

The present study develops a classification model to correlate the binding pockets of 70 HIV-1 protease crystal structures in terms of their structural descriptors to their complexed HIV-1 protease inhibitors. The Random Forest classification model is used to reduce the chemical descriptor space from 456 to the 12 most relevant descriptors based on...

In this paper, we discuss a novel priority assignment and packetization scheme to transport H.264/AVC video packets over wireless networks. Specifically, we discuss a comprehensive packet priority assignment scheme for unequal error protection, followed by the use of adaptive network abstraction layer unit (NALU) sizes and NALU fragmentation scheme...

We present a cross-layer and multilevel unequal error protection (UEP) approach for robust video transmission over noisy wireless channels. We combine the UEP schemes at the application layer (i.e., multi-level unequal importance of compressed H.264/AVC video data) and physical layer (multi-resolution asymmetric 8-PSK modulation). The proposed sche...

An event-to-sink reliable transport (ESRT) control scheme was recently proposed to address the event-to-sink reliability issues in wireless sensor network (WSN). In this paper, we study the performance of ESRT in the presence of ‘over-demanding’ event reliability, using both the analytical and simulation approaches. We show that the ESRT protocol d...

This paper proposes AM-AOMDV, a novel multi-metric and multipath reactive routing scheme for wireless ad hoc networks. The AM-AOMDV extends the AOMDV scheme by including a multiple route metrics, a novel local route update and route maintenance algorithm. The algorithm uses the one-hop information exchange between neighboring nodes to increase the...

We propose a receiver-oriented resource reservation mechanism, called dynamic management of QoS with priority (DMQP), for multimedia multicasting over the internet that provides quality of service (QoS) guarantees with service differentiation for heterogeneous users. In the DMQP protocol, a real-time application requests QoS by specifying a range o...

In this paper we discuss a novel multihop transport scheme for wireless sensor and actor networks (WSAN) that facilitates (a) reliable multihop data packet transmission from the sensor nodes to a centralized controller (sink), and (b) reliable multihop control packet transmission from the sink to different actor nodes. The transport scheme works on...

Summary Underwater Acoustic Networks (UANs) have important applications in ocean exploration and lake pollution monitoring. UANs are however different from terrestrial sensor networks due to their highly variable, long propagation delay, and mobility. Clock synchronization is an important protocol to achieve timing-based sensor communications. In t...

Using a shape analysis technique, a dataset of 83 (20 wild-type and 63 mutated) HIV-1 protease crystal structures is analyzed for the shape changes in their binding pockets. The structures were reported with different bound inhibitors (ligands) and consist of a variety of mutations. Several geometrical and topological attributes based on the volume...

The prediction of biological activity of a chemical compound from its structural features, representing its physico-chemical properties, plays an important role in drug discovery, design and development. Since the biological data is highly non-linear, the machine-learning techniques have been widely used for modeling it. In the present work, the cl...

The interaction between multicasting and real-time multimedia streams poses various new and interesting problems in research on communication protocols and architectures. For example, display systems of heterogeneous users in the same session may have different or even varying latency, display resolution, and/or processing capabilities. In this pap...

In this paper, we discuss a novel reservation-based, asynchronous MAC protocol called 'Multi-rate Multi-hop MAC Protocol' (MMMP) for multi-hop ad hoc networks that provides QoS guarantees for multimedia traffic. MMMP achieves this by providing service differentiation for multi- rate real-time traffic (both constant and variable bit rate traffic) an...

In this paper, we analyze the performance of peer-to-peer video telephony (VT) services over 1x EV-DO Revision A (DOrA) cellular networks. Through simulation studies in OPNET, we illustrate the throughput and delay of both video and voice data during multiple video telephony sessions under varying traffic density (number of users, video bit rate an...

It is important to consider fast and reliable detections of sensing events occurring in various parts of the sensor network. We propose a cluster-based, energy-aware event-detection scheme where events are reliably relayed to a sink in the form of aggregated data packets. The clustering scheme provides faster and better event detection and reliabil...

New wireless technologies, such as wireless LAN and sensor networks, for telecardiology purposes give new possibilities for monitoring vital parameters with wearable biomedical sensors, and give patients the freedom to be mobile and still be under continuous monitoring and thereby better quality of patient care. This paper will detail the architect...

Image-guided percutaneous interventions have successfully replaced invasive surgical methods in some cardiologic practice, where the use of 3D-reconstructed cardiac images, generated by magnetic resonance imaging (MRI) and computed tomography (CT), plays an important role. To conduct computer-aided catheter ablation of atrial fibrillation accuratel...