Milica Stojanovic's research while affiliated with Northeastern University and other places

Publications (173)

Article
The papers in this special section were presented at the Underwater Communications and Networking (UComms) conference that was held August 28–30, 2018, in Lerici, Italy.
Article
Underwater acoustic communications and networking technologies are critical tools for underwater exploration, subsea resource extraction, national defensemissions, etc. Their roles are becoming ever more important as nations around the globe turn to the oceans as sustainable sources of food and energy. The quest for acoustic communications has stea...
Article
In this paper, we investigate an automatic repeat request (ARQ) for reliable transmission over half-duplex links. We design a method based on grouped packet coding (GPC) that combines a stop-and-wait (S&W) ARQ procedure with random linear packet coding and selective acknowledgments applied to groups of coded packets. Our goal in doing so is to boos...
Article
Acoustic links are challenged by high bit error rates, which cause data packets to be declared as erroneous. To prevent the packet loss and achieve reliable data transmission over such links, some form of feedback must be implemented to deliver acknowledgments from the receiver to the transmitter, thus initiating re-transmission of erroneous packet...
Article
We consider random linear packet coding for fading channels with long propagation delays, such as underwater acoustic channels. We propose a scheme in which the number of coded packets to transmit is determined to achieve a prespecified outage/reliability criterion and investigate joint power and rate control with constrained resources. Using the c...
Conference Paper
We investigate reliable data packet delivery employing random linear packet coding for a half-duplex underwater acoustic link. Packet coding is performed on a group of M information-bearing packets so as to form N ≥ M coded packets, where N is chosen such that a pre-specified probability of successful decoding is maintained at the receiver. We rega...
Chapter
Marine robots communicating wirelessly is an increasingly attractive means for observing and monitoring the ocean, but acoustic communication remains a major impediment to real-time control. In this paper we address through experiments the capability of acoustics to sustain highly dynamic, multi-agent missions, in particular range-only pursuit in a...
Article
Full-text available
We develop an adaptive sensing framework for tracking time-varying fields using a wireless sensor network. The sensing rate is iteratively adjusted in an online fashion using a scheme that relies on an integrated sensing and communication architecture. As a result, this scheme allows for an implementation that is both energy efficient and robust. T...
Article
Actuated sensor networks enabled by underwater acoustic communications can be efficiently used to sense over large marine expanses that are typically challenged by a paucity of resources (energy, communication bandwidth, number of sensor nodes). Many marine phenomena of interest admit sparse representations, which, coupled with actuation and cooper...
Conference Paper
We consider random linear packet coding for an underwater acoustic broadcast network. Joint power and rate control is considered as a means to overcome the effects of channel fading. Two main constraints are imposed in our optimization: (i) the transmit power cannot exceed a maximal value, and (ii) the number of coded packets should not exceed a ma...
Article
The special issue showcases selected papers arising out of the Underwater Communications and Networking Conference held in Sestri Levante, Italy, September 3???5, 2014 (UComms14), second in a series of focused meetings intended to bring the best in the field together to present,discuss, and review the state of the art. Major topics span from physic...
Conference Paper
Random linear packet coding combined with adaptive power and rate control is being considered as an alternative to traditional ARQ techniques for the underwater acoustic channel. We first analyze a scheme where the number of coded packets to transmit is determined so as to achieve a pre-determined reliability at the receiver, and hence eliminate th...
Article
Random linear packet coding is considered for channels that experience fading and have long propagation delay, such as the underwater acoustic channels. Previously, we employed power control (adjusting the transmission power according to the channel gain) and rate control (adjusting the number of coded packets according to the channel gain) to coun...
Article
Random linear packet coding is considered for underwater acoustic communications in situations where reliability is essential, i.e., where data packet delivery has to be guaranteed with some probability. We develop an adaptive power and rate control strategy for a half duplex acoustic channel in which the receiver can inform the transmitter about t...
Article
Random linear packet coding is considered for efficient broadcasting in networks with large propagation delays, such as underwater acoustic networks. To additionally overcome the effects of fading, we combine packet coding with adaptive power control, whereby the transmitter adjusts its power upon receiving feedback from the receiver on the current...
Conference Paper
This article considers the problem of packet scheduling for localization in an underwater acoustic sensor network where sensor nodes are distributed randomly in an operating area. Our goal is to minimize the localization time, and to do so we consider two packet transmission schemes, namely collision-free, and collision-tolerant. Through analytical...
Article
This article considers the joint problem of packet scheduling and self-localization in an underwater acoustic sensor network where sensor nodes are distributed randomly in an operating area. In terms of packet scheduling, our goal is to minimize the localization time, and to do so we consider two packet transmission schemes, namely a collision-free...
Article
Full-text available
In this paper, we explore design aspects of adaptive modulation based on orthogonal frequency-division multiplexing (OFDM) for underwater acoustic (UWA) communications, and study its performance using real-time at-sea experiments. Our design criterion is to maximize the system throughput under a target average bit error rate (BER). We consider two...
Article
As analysis of imagery and other science data plays a greater role in mission execution, there is an increasing need for autonomous marine vehicles to transmit these data to the surface. Communicating imagery and full-resolution sensor readings to surface observers remains a significant challenge. Yet, without access to the data acquired by an unma...
Conference Paper
We consider tracking of multiple objects using a wireless sensor network where distributed nodes transmit to a fusion center using random access. During an initialization phase, targets are identified on a discrete set of locations using a sparse identification method. Tracking then proceeds to update the target locations and amplitudes explicitly,...
Article
Underwater acoustic channel models provide a tool for predicting the performance of communication systems before deployment, and are thus essential for system design. In this paper, we offer a statistical channel model which incorporates physical laws of acoustic propagation (frequency-dependent attenuation, bottom/surface reflections), as well as...
Article
Advances in underwater acoustic communications technology are being enabled by more access to in-water data and an infusion of new techniques, researchers, and students. In-water data collection is being made possible by robust funding in the United States, the European Union, and other countries, typically to multiorganization consortia working on...
Article
Full-text available
This is the second in a two-part series of papers on information-theoretic capacity scaling laws for an underwater acoustic network. Part II focuses on a dense network scenario, where nodes are deployed in a unit area. By deriving a cut-set upper bound on the capacity scaling, we first show that there exists either a bandwidth or power limitation,...
Article
Full-text available
In this two-part paper, information-theoretic capacity scaling laws are analyzed in an underwater acoustic network with n regularly located nodes on a square, in which both bandwidth and received signal power can be limited significantly. Parts I and II deal with an extended network of unit node density and a dense network of unit area, respectivel...
Article
Random Access Compressed Sensing (RACS) is an efficient method for data gathering from a network of distributed sensors with limited resources. RACS relies on integrating random sensing with the communication architecture, and achieves overall efficiency in terms of the energy per bit of information successfully delivered. To address realistic depl...
Article
In this paper, we focus on orthogonal frequency-division multiplexing (OFDM) receiver designs for underwater acoustic (UWA) channels with user- and/or path-specific Doppler scaling distortions. The scenario is motivated by the cooperative communications framework, where distributed transmitter/receiver pairs may experience significantly different D...
Conference Paper
We investigate data collection over an underwater acoustic communication network, where sensor nodes are deployed to measure an environmental process. To enhance the energy-efficiency, the network is organized into a hierarchical structure, in which multiple local fusion centers collect the information and convey it to a master fusion center. The m...
Article
Random linear packet coding is considered for use over underwater acoustic channels where long delays challenge the efficiency of standard ARQ. Adaptive power control and rate control are explored to overcome the effect of fading, while minimizing the average energy per successfully transmitted bit of information. Two extreme scenarios are consider...
Conference Paper
Marine robots are an increasingly attractive means for observing and monitoring the ocean, but underwater acoustic communications remain a major challenge. The channel exhibits long delay spreads with frequency-dependent attenuation; moreover, it is time-varying. We consider the minimum energy wireless transmission problem [MET], augmented by the p...
Conference Paper
Underwater acoustic (UWA) channel models provide a tool for predicting the performance of communication systems prior to system deployment and are thus essential for system design. Small-scale modeling of the UWA channel targets statistical characterization of random effects such as scattering and motion-induced Doppler shifting. In this study, eac...
Conference Paper
We analyze the performance of underwater acoustic random access networks. The assumption is that the nodes are distributed in the plane according to a two dimensional Poisson point process. This is a suitable model for a network of bottom mounted nodes. The node-to-node channel is modeled based on an underwater acoustic propagation path loss and fa...
Article
In this work we explore the feasibility of a cognitive acoustic communication system that exploits a dynamic closed loop between the transmitter and receiver with the goal of maximizing the information throughput. Specifically, we design a power control mechanism and couple it with an adaptive modulation method based on orthogonal frequency divisio...
Article
Full-text available
This paper investigates the signal-to-interference ratio and the achievable rates of underwater acoustic (UA) OFDM systems over channels where time and frequency dispersion are high enough that (i) neither the transmitter nor the receiver can have a priori knowledge of the channel state information and (ii) intersymbol/intercarrier interference (IS...
Article
In this paper, we investigate the effect of packet size selection on the performance of media access control (MAC) protocols for underwater wireless sensor networks, namely, carrier sense multiple access (CSMA) and the distance-aware collision avoidance protocol (DACAP). Our comparative analysis, conducted via ns-2 simulations, considers scenarios...
Article
For networks that are deployed for long-term monitoring of environmental phenomena, it is of crucial importance to design an efficient data gathering scheme that prolongs the life-time of the network. To this end, we consider a Random Access Compressed Sensing (RACS) scheme that considerably reduces the power and bandwidth usage of a large network....
Conference Paper
In this work we explore the performance of a selective decision directed (DD) channel estimation (CE) method for orthogonal frequency division multiplexing (OFDM) based communications over multipath Rician fading channels, where fading is modeled as an auto-regressive (AR) random process. The method is based on soft-selection of data sub-carriers t...
Article
Full-text available
We examine the problem of utilizing an autonomous underwater vehicle (AUV) to collect data from an underwater sensor network. The sensors in the network are equipped with acoustic modems that provide noisy, range-limited communication. The AUV must plan a path that maximizes the information collected while minimizing travel time or fuel expenditure...
Conference Paper
This work focuses on random linear packet coding as an efficient method for reliable high-speed underwater communications over acoustic links with long delay. The transmitter sends coded packets with a pre-determined redundancy over a simplex link with no feedback. The receiver checks each received packet, discarding packets with errors, until the...
Article
Divers executing strategic underwater missions as well as recreational divers have a great need for communication. Divers can communicate between themselves as well as to a surface boat, to share information, perform cooperative maneuvers and call for help. In addition, it would be useful to know the location of all divers relative to the boat. Suc...
Article
We address efficient data gathering from a network of distributed sensors deployed in a challenging field environment with limited power and bandwidth. Utilizing the low-rank property of the sensing field, we leverage results from the matrix completion theory to integrate the sensing procedure with a simple and robust communication scheme based on...
Article
This paper examines the main approaches and challenges in the design and implementation of underwater wireless sensor networks. We summarize key applications and the main phenomena related to acoustic propagation, and discuss how they affect the design and operation of communication systems and networking protocols at various layers. We also provid...
Conference Paper
Full-text available
We examine the problem of collecting data from an underwater sensor network using an autonomous underwater vehicle (AUV). The sensors in the network are equipped with acoustic modems that provide noisy, range-limited communica-tion to the AUV. One challenge in this scenario is to plan paths that maximize the information collected and minimize trave...
Article
We analyze the performance of underwater acoustic ad-hoc networks in the presence of interference. We assume a uniform distribution of nodes over a finite area, and focus for simplicity on a two-dimensional network. The node-to-node channel is modeled using frequency dependent path loss and Ricean fading. We adopt a communication theoretic approach...
Conference Paper
We consider a hierarchical underwater acoustic sensor network architecture in which the sensors and the collector stations operate in distinct layers. The hierarchical architecture is motivated by the property of the acoustic underwater transmission medium that for each transmission distance there exists an operating frequency for which the narrow-...
Conference Paper
This paper addresses the feasibility of underwater wireless video transmission using an acoustic system, which consists of a video compressor/decompressor and an OFDM modulator/demodulator. This work includes two main parts: the design of an algorithm aimed to compensate for the Doppler effect and the assessment of a set of error resilience tools o...
Article
In this paper we propose new bounds on the achievable information rate for discrete-time Gaussian channels with intersymbol interference (ISI) and independent and uniformly distributed (i.u.d.) channel input symbols drawn from finite-order modulation alphabets. Specifically, we are interested in developing new bounds on the achievable rates for spa...
Article
We address the design of a large-scale sensor network, deployed for long-term environmental monitoring. Taking into account the sparse nature of the monitored field, we integrate the sensing and the communication aspects of the network into an efficient Random Access Compressed Sensing (RACS) scheme. RACS is inspired by the theory of compressed sen...
Conference Paper
In this paper we analyze the performance of adaptive orthogonal frequency division multiplexing (OFDM) for underwater acoustic (UWA) communications. Our goal is to maximize the system throughput under a target average bit error rate (BER). We consider two different schemes based on the level of adaptivity: in the first scheme only the modulation le...
Article
Full-text available
Information-theoretic throughput scaling laws are analyzed in an underwater acoustic network with n regularly located nodes on a unit square, in which both bandwidth and received signal power can be severely limited. A narrow-band model is assumed where the carrier frequency is allowed to scale as a function of n. We first characterize an attenuati...
Article
Full-text available
Inspired by the theory of compressed sensing and employing random channel access, we propose a distributed energy-efficient sensor network scheme denoted by Random Access Compressed Sensing (RACS). The proposed scheme is suitable for long-term deployment of large underwater networks, in which saving energy and bandwidth is of crucial importance. Du...
Conference Paper
In this paper we explore the performance of a selective decision directed channel estimation (CE) method for underwater acoustic (UWA) orthogonal frequency division multiplexing (OFDM) based communications. The method is based on hard or soft selection of data sub-carriers that are used in the decision directed mode. Particularly, in the process of...
Article
Pre-deployment calculations of the received signal strength in an underwater acoustic channel typically rely on beam tracing of a single-frequency signal for a given (frozen) ocean geometry. The results of such modeling provide an accurate but limited view of transmission loss since acoustic communication systems are necessarily wideband (a typical...
Conference Paper
We investigate the possibility of using orthogonal frequency division multiple access (OFDMA) for design of efficient underwater acoustic (UWA) networks. The major challenge for the OFDMA-based UWA communication systems is the Doppler-induced frequency scaling, which may cause severe intercarrier interference (ICI), and depending on the particular...
Conference Paper
Experimental measurements of shallow water acoustic channels show that the received signal power varies over time as the channel experiences fading. This fact motivates the use of adaptive power (or rate) control as a way to improve the system performance or save the transmit power. In a system with adaptive power control, the transmitter adjusts i...
Conference Paper
A neighbor discovery protocol is proposed for initializing an ad-hoc deployable autonomous underwater system in which the nodes (floating sensors, crawlers, vehicles) have no knowledge of the system topology upon deployment. The goal is to establish multi-hop, minimum-power acoustic communication links over a given coverage area. The protocol uses...
Conference Paper
Full-text available
In this paper we explore the feasibility of predicting an underwater acoustic (UWA) channel impulse response one travel time ahead. Our work is motivated by the design of UWA communication systems that will employ adaptive modulation, whose performance relies on the ability to predict the channel up to a few seconds into the future. The possibility...
Article
Orthogonal frequency division multiplexing (OFDM) has emerged as a promising modulation scheme for underwater acoustic (UWA) communications, thanks to its robustness to channels with severe time dispersion. Compared to conventional single-carrier systems, for which complicated equalization schemes are usually required, OFDM systems are in general m...
Conference Paper
Full-text available
For networks that are deployed for long-term monitoring of environmental phenomena, it is of crucial importance to design an efficient data gathering scheme that prolongs the lifetime of the network. To this end, we exploit the sparse nature of the monitored field and consider a Random Access Compressed Sensing (RACS) scheme in which the sensors tr...
Article
Full-text available
Capacity scaling laws are analyzed in an underwater acoustic network with $n$ regularly located nodes on a square, in which both bandwidth and received signal power can be limited significantly. A narrow-band model is assumed where the carrier frequency is allowed to scale as a function of $n$. In the network, we characterize an attenuation paramet...
Conference Paper
Full-text available
Fast and accurate Carrier Frequency Offset (CFO) estimation is a problem of significance in many multi-carrier modulation based systems, especially in uplink Orthogonal Frequency Division Multiple Access (OFDMA) where the presence of multiple users exacerbates the inter-carrier interference (ICI) and results in multi-user interference (MUI). In thi...
Conference Paper
Full-text available
We study an online random linear network coding approach for time division duplexing (TDD) channels under Poisson arrivals. We model the system as a bulk-service queue with variable bulk size and with feedback, i.e., when a set of packets are serviced at a given time, they might be reintroduced to the queue to form part of the next service batch. W...
Conference Paper
Full-text available
Underwater acoustic (UWA) channels are typically characterized by a multipath structure with large delay spread, where only a few propagation paths carry significant energy. Each path exhibits time variability, which, together with the transmitter and receiver motion, induces Doppler spreading and shifting of the signal. In this paper, we analyze t...
Conference Paper
Full-text available
Accurate time scale compensation is a problem of significance for underwater acoustic channels. Using our proposed partial FFT Demodulation technique, we consider two algorithms for fast and accurate data detection over time scale distorted channels. We present a theoretical analysis to characterize the performance of these algorithms and determine...
Conference Paper
Full-text available
Multiple-input multiple-output (MIMO) communications based on orthogonal frequency division multiplexing (OFDM) are considered for improving the performance and bandwidth utilization of underwater acoustic systems in which cooperation is possible between distributed transmitters. The major challenge in such a framework - and the principal differenc...
Conference Paper
We consider the performance of underwater acoustic ad-hoc networks in the presence of interference. We assume a uniform distribution of nodes over a finite area. The node-to-node channel is modeled using frequency dependent path loss and Ricean fading. We adopt a communication theoretic approach and study the interdependence of the sustainable numb...
Conference Paper
Doppler distortion causes inter-carrier interference which prevents the use of differentially coherent detection in OFDM systems. To recover this efficient detection method, we propose to use several FFT demodulators operating in parallel over non-overlapping time segments, and to combine their outputs prior to detection. This technique aims for ef...
Conference Paper
The paper considers the performance of clustered underwater acoustic ad-hoc networks in the presence of interference. We assume a uniform distribution of nodes over a finite area. The cluster-to-cluster channel is modeled as a Ricean fading channel. We adopt a communication theoretic approach and study the interdependence of the sustainable number...
Article
We consider the performance of clustered underwa-ter acoustic ad-hoc networks. We assume a uniform distribution of nodes over a finite area. The nodes in the network form clusters. The information is transmitted across the network from cluster to cluster with nodes in each cluster organized as virtual transmit/receive arrays. The cluster-to-cluster...
Article
Path loss in an underwater acoustic channel depends not only on the transmission distance, but also on the signal frequency. As a result, the useful bandwidth decreases with distance, a feature not normally present in terrestrial radio networks. This fact motivates the use of multihop communications in an acoustic network, and strongly influences i...
Article
In this paper, a multihop underwater acoustic line network, which consists of a series of equal-distance hops connected by relay transceivers in a tandem, is considered. Messages are originated as coded packets from a source node at one end, relayed sequentially hop by hop (decoded and re-encoded), and finally received by a destination node at the...
Conference Paper
Full-text available
In this paper, we propose a power-efficient underwater sensor network scheme employing compressed sensing and random channel access. The proposed scheme is suitable for applications where a large number of sensor nodes are deployed uniformly over a certain area to measure a physical phenomenon. The underlying assumption is that most physical phenom...
Conference Paper
We study the feasibility of video transmission using an acoustic system for deep-sea oilfield supervisory control and inspection. Such a system is of interest over short distance links, with short delays and high available bandwidth, as near real-time imagery can be transmitted to monitor targeted underwater spots. This work includes three parts: (...
Conference Paper
To obtain full benefits of the Alamouti space-time code design on a time-varying acoustic channel, the channel variation is decoupled into two parts: the gain, which is assumed to be constant over an Alamouti pair (two consecutive OFDM blocks), and the phase, which is not restricted in this manner, but allowed to vary from one block to another in a...
Conference Paper
We consider the performance of underwater acoustic ad-hoc networks. We assume a uniform distribution of the nodes over a finite area. The node-to-node channel is modeled through the Ricean fading model. We adopt a communication theoretic approach and study the interdependence of the sustainable number of hops through the network, end-to-end frame e...
Conference Paper
We propose a hierarchical underwater acoustic sensor network architecture in which the sensors and the collector stations operate in distinct layers. The hierarchical architecture is motivated by the property of the acoustic underwater transmission medium that for each transmission distance there exists an operating frequency for which the narrowba...
Conference Paper
In mobile OFDM systems, such as underwater acoustic and digital video broadcasting (DVB) systems, time variation causes severe inter-carrier interference (ICI) which limits data detection performance. To address this problem, a signal processing strategy using several partial-interval FFTs instead of a conventional full-interval single FFT is propo...
Conference Paper
Energy-efficiency in underwater networks is a key issue that affects all aspects of network design, from hardware to protocols and applications. In this paper we analyze the impact of node density on the energy consumption in transmission, reception and idle-listening, in a network where nodes follow a duty cycle scheme. We consider the energy perf...
Conference Paper
Full-text available
Two MAC layer protocols are considered for multi-hop underwater acoustic networks: Pure CSMA, suitably configured to perform over a long-delay channel, and the Distance-Aware Collision Avoidance Protocol (DACAP), a protocol specifically designed for collision avoidance via a distributed coordination function à la IEEE 802.11. We investigate the imp...
Conference Paper
Full-text available
Random access protocols for multi-hop underwater wireless sensor networks that use control packets such as RTS/CTS have been shown to reduce or eliminate collisions between data packets, but they typically remain prone to collisions between control and data packets. Although control packets are usually much shorter than the data packets, when a con...
Conference Paper
Alamouti space-time coding is investigated in conjunction with OFDM modulation for high-rate underwater acoustic communications over time varying channels. The scheme's diversity gain is exploited using a low-complexity adaptive multichannel receiver. Performance is demonstrated using experimental data transmitted in a 10 kHz bandwidth over a 1 km...