Department Publications

Increasing demands for faster, more responsive and manageable networks have brought about a different approach to networking - Software Defined Networking (SDN). SDN introduces flow-based networking with a centralized controller. Matching incoming traffic flows with rules sent by the controller is an integral part of traffic forwarding in SDN. How efficiently this is carried out has a huge impact on network performance. In this paper, we present a high-performance, low-cost architecture for flow matching in an SDN switch. Our architecture consists of a dedicated unit for flow matching and a custom processor. Novel design of the flow match unit reduces matching latency significantly, when compared with the generic architecture, while also reducing usage of costly resources like TCAMs. When testing on FPGA platforms, implementing the system required only a minimum amount (around 10% on Virtex-7) of …

Since recently, UAVs (Unmanned Aerial Vehicles) have increasingly been recognized as a reliable, and effective means of aerial surveillance. Deployment of UAVs in disaster management for aerial surveillance and real-time video feed, when land access is cut off, is one of the most prominent applications. The ability of small, lightweight UAVs in aerial access and gathering data, in areas that are insecure or impossible for humans to reach has significantly improved remote accessibility. In this research, a new low cost small scale UAV with fully-fledged autopilot system on board the aircraft with the capabilities of following a predefined path and returning home autonomously has been designed, built, and tested successfully. This small-scale UAV is capable of navigating through given GPS coordinates at given altitude, while providing real-time flying status back to the ground control station.

Multiple antenna techniques, that allow energy beamforming, have been looked upon as a possible candidate for increasing the efficiency of the transfer process between the energy transmitter (ET) and the energy receiver (ER) in wireless energy transfer. This paper introduces a novel scheme that facilitates energy beamforming by utilizing Received Signal Strength Indicator (RSSI) values to estimate the channel. Firstly, in the training stage, the ET will transmit sequentially using each beamforming vector in a codebook, which is pre-defined using a Cramer-Rao lower bound analysis. The RSSI value corresponding to each beamforming vector is fed back to the ET, and these values are used to estimate the channel through a maximum likelihood analysis. The results that are obtained are remarkably simple, requires minimal processing, and can be easily implemented. Also, the results are general and hold for all …

Everyone is moving towards smart era rapidly with new technologies. This paper focuses on monitoring a building from a remote place to ensure the activities happening in particular locations. Here we have proposed a sensor-based wireless distributed system with people counting and activity detection for a building. A novel approach is used to people count using one motion sensor. A System model is built and experimented in the department of Electronic and Telecommunication Engineering (ENTC), University of Moratuwa. This enables monitoring activities in the lecture hall, lecturer room and lab with high precision.

This paper identifies the challenges involved in designing the 100 Gigabit per second (Gbps) Ethernet Physical Coding Sublayer (PCS) Semiconductor Intellectual property (IP) compliant with IEEE 802.3 standard. Challenges are discussed under the two topics, implementation challenges and verification challenges. Furthermore, our solutions to identified challenges are presented in the paper.

This paper presents the implementation and analysis of a low complex architecture for a fast locking Phase Locked Loop. In this paper, we analyse a high speed mixed signal PLL architecture and its components such as phase frequency detector, charge pump, voltage controlled oscillator etc. are further reviewed. The simulation results show that proposed PLL design achieves locking within 1 μβ and it operates at 5 GHz featuring a significant P k -P k jitter value less than 10 ps and root-mean-square jitter less than 5 ps. Mathematical modeling and simulations of the proposed PLL architecture are also presented.

The P300 Speller is a Brain Computer Interface that enables communication using the EEG signal. The P300 wave is an Event Related Potential that occurs as a response to a familiar stimulus. This system can be used to aid persons who are unable to communicate via conventional methods. In this paper, the P300 Speller has been modified to allow communication in three languages: English, Sinhala and Tamil. Classification of the P300 waveform was done using an ensemble of Support Vector Machines. A mean letter classification accuracy of 83.76% and a mean P300 classification accuracy of 90.68% was achieved on our dataset.

Electrophysiology has recently evolved into an interactive, high-throughput endeavor. Recording from dozens to hundreds of electrodes is today routine; novel means of manipulating the system in real time, through electrical stimulation, optogenetics or sensory manipulation are allowing us to decipher neural circuit function at an unparalleled rate. To contribute to the wide dissemination of such techniques, we present an open hardware project, High-Channel Count Electrophysiology (HiCCE), aiming to produce low-cost, high-channel count (≥128 channels) electrophysiology instrumentation capable of fast data acquisition rates, real-time processing and feedback capabilities. Our design is centered on an open standard, FPGA Mezzanine Card (FMC), which permits a varied choice of FPGA carrier architectures suited to different laboratory experimental needs. The HiCCE-128, a low-cost highperformance 128 …

Memory Based Event Triggering (MBET) is a pragmatic approach to reduce the effective sampling rate of a control system. In MBET, periodically sampled state variables and control inputs are encoded such that data transmission takes place only when they change by a value that exceeds a predetermined threshold. This results in a significant reduction of network traffic in Networked Control Systems (NCS). Should MBET encoding result in an asymptotic cyclic behavior (limit cycle like behavior), it would result in a lower bound in the required bandwidth. In this paper, the necessary conditions for the formation of such a cycle are investigated. It is demonstrated analytically as well as through empirical simulations that the main requirement for the occurrence of asymptotic dynamic cycles is a diffeomorphism between a scalar control input and a unique equilibrium point to which the system will converge to for a constant …

Frequently, a physical plant of a control system has an optimum operating point such as the spark (or injection) time of an internal combustion engine that results in maximum torque. Extremum Seeking Control (ESC) is a method of adaptive control capable of locating and maintaining a plant at such an optimum operating point in real time. It is capable of doing so with minimal a priori knowledge of the plant and can also track slowly varying changes. Input perturbed ESC schemes that use periodic dither signals have the disadvantage of requiring a high bandwidth for sampling and correlating the plant output with the dither signal. If the feedback path was to be implemented over a packet switched communication network, the high bandwidth requirement could result in increased congestion and consequently packet delays and dropouts. As a solution encoding using sporadic (aperiodic) sampling techniques can be used in the feedback path of the ESC scheme to reduce the required bandwidth. However, in order to ensure convergence of the ESC scheme with encoding, the effect of the signal reconstruction error due to encoding on the critical correlation stage has to be investigated. The contribution of this paper is an investigation of the convergence requirements and bandwidth performance of two encoding schemes; Memory-Based Event Triggering (MBET) and Event Triggered Adaptive Differential Modulation (ETADM). The results show that MBET can fail for objective functions with plateaus. ETADM fails when the number of ETADM steps used for reconstructing the plant output per perturbation cycle is too low to allow correlation. In terms of …

This paper analyses the receiver of 40GBASE PCS Sub layer specified by IEEE 802.3ba CSMA/CD standards. Based on the analysis, possible optimization parameters for the receiver FIFO are identified. Proper functionality of the proposed design is verified with simulation results. The optimization of receiver FIFO design may lead to reduce the gate count, area and power consumption in ASIC design.

We present the development and testing of a cellular network built on open source technologies. This network supports voice calls and text messages within the network or between networks. The main objective of this work is to develop a stand-alone mobile network consisting of one base station and a switch, the access to which can be controlled as required. The mobile network is also connected to public networks. The designed network is based on Global System for Mobile Communications (GSM). Our work includes the configuration of the embedded hardware components, selection and integration of the proper software combination, testing of compatible versions of the software, hardware-software integration within the embedded system, and interconnecting the systems via the Internet. The key contribution and novelty of the project is the development of a stand-alone mobile network base station/ switch …

1.1 Background 1 1.2 Problem Statement 3 1.3 Proposed system 4 1.4 Objectives 4 1.5 Deliverables 4

The achievable average rate of a full-duplex (FD) multiple-input-single-output interference channel with linear transceiver structures is analyzed. The impact of transmit front-end noise is included in the analysis. Both cooperative and non-cooperative strategies for the FD interference channel are considered and the closed-form expressions are derived for the achievable average rate of each strategy.

We present a novel non-invasive current measuring platform that estimates the current through a bundled cable. The sensor platform contains eight three axis magnetometer breakout sensors. We develop a regression model to estimate the current flowing in the wire using captured data from the sensor platform. The model in the paper demonstrated accurate results for current estimation of two core wire (7.2 mm diameter) with mean absolute error as low as 0.03 A and root mean square error as low as 0.06 A. This work can be used to develop a plug and play instrument that can non-invasively measure current in a system without disturbing its behavior in operating environment.

Moringa oleifera, commonly known as “Murunga” in Sri Lanka, is a valuable multi-purpose tree that grows in arid tropical climates. This tree is easily accessible at very low cost to rural populations as a rich source of nutrition and medicine. Its leaves contain proteins, essential amino acids, vitamins A and C, minerals and carbohydrates. The leaves are consumed directly with food, or as dried powder ingredient for making herbal tea. The medical properties of the leaves include anti-inflammatory, anti-fibrosis, anti-microbial, antioxidant, anti-hyperglycaemic, anti-tumour and cancer preventative properties. When direct solar drying is used, the process takes up to four days. Solar collectors can achieve this within a single day. Furthermore solar collectors prevent damage to the produce by ultraviolet radiation and contamination from dust and atmospheric pathogens. However, due to the high moisture content of Moringa …

The rapid advancement of technology has made the telecommunication sector very competitive. In order to keep up with the competition, telecommunication operators have to identify the exact needs of the customers and offer services in-line with the customer needs. The aim of this research is to find out how data mining can be applied to identify customer needs and how telecommunication companies can benefit from using data mining techniques in their business and how to develop a data mining framework for identifying the customer needs in order to develop products and services to increase the revenue levels of the companies. The objective of this study includes the investigation of the relationship between data mining practices and the customer behavior patterns, the relationship between customer needs and products or services, relationship between new product design initiatives and revenue increases of the companies, the impact of data mining on the revenue of telecommunications companies and the development of the data mining frame work to improve the overall ARPU levels of the industry and a Business Intelligence (BI) tool to enhance decision making for improving the overall ARPU levels of the industry. Firstly the conceptual model is developed to indicate the main information areas that the study seeks to provide insights on and is tested through a sample of employees who hold positions in the telecommunications sector. This model has four main variables; an independent variable (data mining), two intermediate variables (customer behavior and product) and a dependent variable (increased revenue). Secondly the …

With the popularization of a quad high-definition/4K video being dependent on the availability of real-time High Efficiency Video Coding (HEVC) decoders, hardware implementations have become more appealing due to their superior performance and low power consumption. In this paper, a field-programmable gate array (FPGA)-based hardware implementation of a 4K 30 frames/s real-time HEVC decoder is presented. An elastically pipelined decoder architecture is used to absorb variations in processing time and each pipeline stage is optimized to use available FPGA primitives. FPGA-specific challenges in managing critical path delays to achieve a target operating frequency of 150 MHz required many architectural novelties, such as exploitation of the sparsity of transformed coefficient matrix, single-cycle reference pixel processing in intra prediction, and flexible block ordering in deblocking filter/sample …

Five-dimensional (5-D) light field video (LFV) (also known as plenoptic video) is a more powerful form of representing information of dynamic scenes compared to conventional three-dimensional (3-D) video. In this paper, the 5-D spectrum of an object in an LFV is derived for the important practical case of objects moving with constant velocity and at constant depth. In particular, it is shown that the region of support (ROS) of the 5-D spectrum is a skewed 3-D hyperfan in the 5-D frequency domain, with the degree of skew depending on the velocity and depth of the moving object. Based on this analysis, a 5-D depth-velocity digital filter to enhance moving objects in LFVs is proposed, described and implemented. Further, by means of the commercially available Lytro light-field camera, LFVs of real scenes are generated and used to test and confirm the performance of the 5-D depth-velocity filters for enhancing such …

We investigate the problem of automatic action recognition and classification of videos. In this paper, we present a convolutional neural network architecture, which takes both motion and static information as inputs in a single stream. We show that the network is able to treat motion and static information as different feature maps and extract features off them, although stacked together. We trained and tested our network on Youtube dataset. Our network is able to surpass state-of-the-art hand-engineered feature methods. Furthermore, we also studied and compared the effect of providing static information to the network, in the task of action recognition. Our results justify the use of optic flows as the raw information of motion and also show the importance of static information, in the context of action recognition.

A 5-D IIR depth-velocity filter is proposed for enhancing objects moving on linear trajectories, with constant velocity and at constant depth, in light field videos (also known as plenoptic videos). The passband of the proposed filter is a plane in the 5-D frequency domain and is realized by cascading three first-order 5-D IIR filters having 4-D hyperplanar passbands of appropriate orientations. Numerical simulation results are presented to confirm the performance of the proposed filter.

In this paper, we focus on the ergodic downlink sum-rate performance of a system consisting of a set of heterogeneous users. We study three user selection schemes to group near-orthogonal users for simultaneous transmission. The first scheme is a random selection policy that achieves fairness, but does not exploit multi-user diversity. The second scheme is a greedy selection policy that fully exploits multi-user diversity, but does not achieve fairness, and the third scheme achieves fairness while partially exploiting multi-user diversity. We also consider two beamforming methods for data transmission, namely, maximum-ratio transmission and zero-forcing beamforming. In all scheduling schemes studied in the paper, there is a key parameter that controls the degrees of orthogonality of channel directions between co-scheduled users. We focus on optimally setting this parameter for each scheduling scheme such that …