Saman Atapattu

Saman Atapattu
University of Melbourne | MSD ·  Department of Electrical and Electronic Engineering

PhD

About

94
Publications
15,014
Reads
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2,847
Citations
Additional affiliations
August 2013 - May 2014
University of Alberta
Position
  • PostDoc Position
September 2008 - August 2013
University of Alberta
Position
  • Research Assistant
January 2005 - December 2006
Asian Institute of Technology
Position
  • MEng

Publications

Publications (94)
Preprint
Incorporating mobile edge computing (MEC) in the Internet of Things (IoT) enables resource-limited IoT devices to offload their computation tasks to a nearby edge server. In this paper, we investigate an IoT system assisted by the MEC technique with its computation task subjected to sequential task dependency, which is critical for video stream pro...
Article
This paper studies the performance and key structural properties of the optimum location-based relay selection policy for wireless networks consisting of homogeneous Poisson distributed relays. The distribution of the channel quality indicator at the optimum relay location is obtained. A threshold-based distributed selective feedback policy is prop...
Preprint
Full-text available
In this letter, we consider an underlay cognitive radio network assisted by dual-hop decode-and-forward (DF) relaying. For a general multi-user network, we adopt a max-min fairness relay selection scheme and analyse the outage probability when the channels are subject to independent and non-identical Nakagami-m fading. The relay network operates wi...
Article
This letter investigates the exploitation of an intelligent reflecting surface (IRS) to communicate securely in a two-way network consisting of an untrusted user. In particular, the transmit powers and the phase shift at each element of the IRS are optimized to maximize the sum-secrecy rate, such that the IRS-reflected and non-IRS-reflected signals...
Preprint
The reconfigurable intelligent surface (RIS) is a promising technology that is anticipated to enable high spectrum and energy efficiencies in future wireless communication networks. This paper investigates optimum location-based RIS selection policies in RIS-aided wireless networks to maximize the signal-to noise ratio (SNR) for a power path-loss m...
Article
We investigate a single-antenna multi-user multi-relay interference network, where multiple source nodes simultaneously communicate with their respective destination nodes via half-duplex decode-and-forward relays. To ensure fairness among users, we consider a power allocation strategy to maximize the worst-case energy efficiency (EE) of all users...
Article
We consider a two–tile reconfigurable intelligent surface (RIS) assisted wireless network with a two-antenna transmitter and receiver over Rayleigh fading. We show that the average received signal-to-noise-ratio (SNR) optimal combining and transmission vectors are given by the left and right singular spaces of the RIS-receiver and transmit-RIS chan...
Preprint
Full-text available
We consider a two--tile reconfigurable intelligent surface (RIS) assisted wireless network with a two-antenna transmitter and receiver over Rayleigh fading. We show that the average received signal-to-noise-ratio (SNR) optimal transmission and combining vectors are given by the left and right singular spaces of the RIS-receiver and transmit-RIS cha...
Article
In this paper, we investigate the two-way communication between two users assisted by a reconfigurable intelligent surface (RIS). The scheme that two users communicate simultaneously over Rayleigh fading channels is considered. The channels between the two users and RIS can either be reciprocal or non-reciprocal. For reciprocal channels, we determi...
Article
Full-text available
Signal detection in colored noise with an unknown covariance matrix has a myriad of applications in diverse scientific/engineering fields. The test statistic is the largest generalized eigenvalue (l.g.e.) of the whitened sample covariance matrix, which is constructed via m-dimensional p signal-plusnoise samples and m-dimensional n noise-only sample...
Preprint
This paper derives the performance and key structural properties of optimum location-based relay selection schemes for wireless networks consisting of spatially deployed decode-and-forward relays. For a homogeneous Poisson point process (PPP) of relays and general path-loss models, we obtain the distribution for channel quality indicator of the rel...
Article
We consider a relay-assisted non-orthogonal multiple access (NOMA) network consisting of a source (S), an energy-constrained relay (R), and two users, where a hybrid power-splitting (PS) and time-splitting (TS) scheme is applied at R for energy harvesting. We provide optimal transmission designs for such a network by jointly optimizing the transmit...
Article
Full-text available
This letter considers integrating a backscatter link with a reconfigurable intelligent surface to enhance backscatter communication while assisting the direct communication. We derive the probability that the backscatter channel dominates in the composite channel. This probability is a useful performance measure to determine the number of reflector...
Article
Full-text available
Employing backscatter communication is a promising solution for Internet of Things (IoT). The novel large intelligent surface (LIS) concept can achieve reliable communication by establishing line-of-sight like channels. This paper thus considers an LIS-aided backscatter system to support high-reliable communications for IoT applications. In this le...
Preprint
In this paper, we investigate the two-way communication between two users assisted by a re-configurable intelligent surface (RIS). The scheme that two users communicate simultaneously in the same time slot over Rayleigh fading channels is considered. The channels between the two users and RIS can either be reciprocal or non-reciprocal. For reciproc...
Preprint
This paper investigates a three-layer IoT-fog-cloud computing system to determine the optimum workload and power allocation at each layer. The objective is to minimize maximum per-layer latency (including both data processing and transmission delays) with individual power constraints. The resulting optimum resource allocation problem is a mixed-int...
Preprint
In this paper, we investigate the two-way communication between two users assisted by a re-configurable intelligent surface (RIS). The scheme that two users communicate simultaneously in the same time slot over Rayleigh fading channels is considered. The channels between the two users and RIS can either be reciprocal or non-reciprocal. For reciproc...
Preprint
The paper considers physical layer security (PLS) of an untrusted unmanned aerial vehicle (UAV) network, where a multitude of UAVs communicate in full-duplex (FD) mode. A source-based jamming (SBJ) scheme is exploited for secure communication without utilizing any external jammers. Firstly, the optimal power allocation between the confidential sign...
Preprint
This paper considers simultaneous wireless information and power transfer (SWIPT) over a dual-hop dynamic decode-and-forward (DF) relay network with the power-splitting (PS) energy harvesting protocol at the relay. The circuit power consumption (CPC), which includes power requirements for both decoding and encoding circuits, is considered at the re...
Article
Full-text available
Ambient backscatter, an emerging green communication technology, has aroused great interest from both academia and industry. One open problem for ambient backscatter communication (AmBC) systems is channel estimation for a massive-antenna reader. In this paper, we focus on channel estimation problem in AmBC systems with uniform linear array (ULA) a...
Preprint
Ambient backscatter, an emerging green communication technology, has aroused great interest from both academia and industry. One open problem for ambient backscatter communication (AmBC) systems is channel estimation for a massive-antenna reader. In this paper, we focus on channel estimation problem in AmBC systems with uniform linear array (ULA) a...
Article
We address the problem of secure wireless communications over an untrusted full-duplex (FD) relay based on the source jamming scheme. The optimal power allocation between the confidential signal and the jamming signal is derived to maximize the secrecy rate. Then the corresponding secrecy outage probability (SOP) and the average secrecy rate (ASR)...
Preprint
This paper investigates the location-based relay selection problem, where the source node chooses its relay from a set of spatially deployed decode-and-forward relays. The advantages of location-based relay selection are the elimination of excessive relay switching rate and the feedback reduction avoiding the requirement of having full channel stat...
Preprint
Full-text available
Signal detection in colored noise with an unknown covariance matrix has a myriad of applications in diverse scientific/engineering fields. The test statistic is the largest generalized eigenvalue (l.g.e.) of the whitened sample covariance matrix, which is constructed via $m$-dimensional $p $ signal-plus-noise samples and $m$-dimensional $n $ noise-...
Preprint
Wireless energy transferring technology offers a constant and instantaneous power for low-power applications such as Internet of Things (IoT) to become an affordable reality. This paper considers simultaneous wireless information and power transfer (SWIPT) over a dual-hop decode-and-forward (DF) relay network with the power-splitting (PS) energy ha...
Preprint
In this paper we consider wireless energy transfer for a point-to-point link. The energy transmitter sees a finite number of independent channel realizations, and, armed with (causal) knowledge of the channels, must decide how much energy to transmit in each time slot. The objective is to maximize the expected energy transferred to the receiver at...
Preprint
Full-text available
This paper investigates the classical statistical signal processing problem of detecting a signal in the presence of colored noise with an unknown covariance matrix. In particular, we consider a scenario where m-dimensional p possible signal-plus-noise samples and m-dimensional n noise-only samples are available at the detector. Then the presence o...
Article
Full-text available
This paper investigates the relay selection (RS) problem for multi-hop full-duplex (FD) relay networks where multiple source-destination (SD) pairs compete for the same pool of relays, under the attack of multiple eavesdroppers. To enhance the physical-layer security, within a given coherence time, our objective is to jointly assign the available r...
Preprint
This paper addresses one of the classical problems in random matrix theory-- finding the distribution of the maximum eigenvalue of the correlated Wishart unitary ensemble. In particular, we derive a new exact expression for the cumulative distribution function (c.d.f.) of the maximum eigenvalue of a $2\times 2$ correlated non-central Wishart matrix...
Article
Full-text available
This paper investigates a user-fairness relay selection (RS) problem for decode-and-forward (DF) full-duplex (FD) relay networks where multiple users cooperate with multiple relays in each coherence time. We consider two residual self-interference (RSI) models with or without direct links. We propose a suboptimal relay selection (SRS) scheme which...
Article
We consider a multi-user, multi-relay network where each source communicates with its destination via an assigned relay. To ensure fairness among the users, the minimum of the users’ energy efficiencies (in bit-per-Joule) is jointly maximized with respect to the relay assignment and transmit power of both source and relay nodes. The resulting algor...
Article
This paper proposes an opportunistic spatial modulation (OSM) scheme where the transmit antennas are divided into K ≥ 1 equal groups, and the best antenna from each group is selected to form a K transmit antenna subset for implementing spatial modulation (SM). Thus, the activation of one antenna from the subset to transmit one of the M-ary modulati...
Article
Full-text available
This letter analyzes the outage probability of an ambient backscatter communication system with a pair of passive tag and reader. Specifically, exact expressions of the effective channel distribution and outage probability of the reader are derived rigorously. Since the outage expression is an infinite sum, a tight truncation error bound is provide...
Article
We consider a distributed detection system for a wireless sensor network (WSN) over slow-fading channels. Each sensor only has knowledge of quantized channel state information (CSI) which is received from the fusion center (FC) via a limited feedback channel. We then consider transmit power allocation at each sensor in order to maximize a J-diverge...
Article
In this paper, we consider multi-hop wireless networks with decode-and-forward relays. Intermediate relays have no fixed power supplies and thus need to replenish energy via wireless energy harvesting from the source signal. The technique of simultaneous wireless information and power transfer (SWIPT) is utilized between every two adjacent nodes to...
Article
Full-text available
Ambient backscatter is an emerging green communication technology that exploits the environmental radio frequency (RF) signals to enable passive devices to communicate with each other. This paper investigates channel capacity and outage performance of ambient backscatter communication systems. Specifically, a calculation method is proposed to facil...
Article
This paper analyzes the performance of a multiuser multihop relay network using a low complexity decentralized relay selection (DRS) scheme for decode-and-forward cooperative networks. We carry out a rigorous diversity order analysis, with Nakagami-m fading and pathloss and show that the DRS scheme achieves full diversity while maintaining a comple...
Article
Full-text available
Here we address the problem of outage characterization of a single-cell multiple-user multiple-input-multiple-output (MU-MIMO) network with matched-filter (MF) precoding at the base-station (BS). In particular, we derive an exact expression for the outage probability of any user. This expression is valid for an arbitrary number of BS antennas and m...
Article
In this paper, we consider a relay network over a flat-fading channel, where the relay has no fixed power supply and thus needs to replenish energy via wireless energy harvesting (EH) from the signals transmitted by the source. We propose a novel hybrid protocol, which is a combination of existing EH protocols, such as power splitting (PS) and time...
Conference Paper
Full-text available
We consider a wireless energy harvesting (EH) relay network. Relays without embedded energy supply harvest energy from the source node. Considering a time switching protocol, performance measures such as average signal-to-noise ratio (SNR), outage and throughput are analyzed. Subsequently, optimal EH time is selected in order to maximize the throug...
Book
Spectrum sensing is critically important for cognitive radio, an emerging solution to the spectrum congestion and low usage of licensed spectrum. Energy detection is a promising low-complexity and low-cost spectrum sensing technique. Its performance analysis has been revisited extensively in the recent literature. This book thus aims at a comprehen...
Chapter
As mentioned before, the energy detector senses spectrum holes by determining whether the primary signal is absent or present in a given frequency slot. The energy detector typically operates without prior knowledge of the primary signal parameters. Its key parameters, including detection threshold, number of samples, and estimated noise power, det...
Chapter
The energy detection process is affected by the fluctuations of the propagation channel, which occur due to path loss, large-scale fading and small-scale fading. Channel correlation is also a major impact when energy detectors are implemented in cooperative spectrum sensing networks [43].
Chapter
Achieving IEEE 802.22 WRAN spectrum sensing specifications is challenging because of shadowing, fading, and time variation of wireless channels. These distortions can be mitigated by using diversity combining and cooperative spectrum sensing techniques. The former improves the receive SNR, and the latter mitigates the hidden terminal problem.
Chapter
Despite the benefits of low complexity and simple structure, the energy detector has several drawbacks.
Article
For spectrum sensing in cognitive radio networks, the IEEE 802.22 standard requires the detection of primary signals with a signal-to-noise ratio (SNR) as low as -20 dB and receiver sensitivity as low as -116 dBm. Under such low-SNR levels, the performance of a conventional energy detector is analyzed in this paper. The analysis includes novel expr...
Book
This Springer Brief focuses on the current state-of-the-art research on spectrum sensing by using energy detection, a low-complexity and low-cost technique. It includes a comprehensive summary of recent research, fundamental theories, possible architectures, useful performance measurements of energy detection and applications of energy detection. C...
Article
Full-text available
This paper studies relay selection schemes for two-way amplify-and-forward (AF) relay networks. For a network with two users that exchange information via multiple AF relays, we first consider a single-relay selection (SRS) scheme based on the maximization of the worse signal-to-noise ratio (SNR) of the two end users. The cumulative distribution fu...
Article
Full-text available
This paper investigates the relay selection (RS) problem in networks with multiple users and multiple common amplify-and-forward (AF) relays. Considering the overall quality-of-service of the network, we first specify our definition of optimal RS for multiple-user relay networks. Then an optimal RS (ORS) algorithm is provided, which is a straightfo...
Article
Full-text available
In this paper, the detection performance of an en- ergy detector used for cooperative spectrum sensing in cognitive radio networks is investigated under very low signal-to-noise ratio (SNR) levels. The analysis focuses on the derivation of closed-form expressions for the false-alarm and the average missed-detection probabilities for two cases over...
Conference Paper
Full-text available
As required in the IEEE 802.22 proposal, spectrum sensing techniques should be capable enough to sense the primary signal with very low receiver sensitivity such as at -116 dBm. In this paper, the detection performance of an energy detector used for spectrum sensing in cognitive radio networks is investigated under such very low signal-to-noise rat...