Engineering Science, School of

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Development of a Novel Contactless Mechanocardiograph Device

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2008
Abstract: 

A novel method of detecting mechanical movement of the heart, Mechanocardiography (MCG), with no connection to the subject's body is presented. This measurement is based on radar technology and it has been proven through this research work that the acquired signal is highly correlated to the phonocardiograph signal and acceleration-based ballistocardiograph signal (BCG) recorded directly from the sternum. The heart rate and respiration rate have been extracted from the acquired signal as two possible physiological monitoring applications of the radar-based MCG device.

Document type: 
Article

On Reliable Transmission of Data over Simple Wireless Channels

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2009
Abstract: 

Standard protocols for reliable data transmission over unreliable channels are based on various Automatic Repeat reQuest (ARQ) schemes, whereby the sending node receives feedback from the receiver and retransmits the missing data. We discuss this issue in the context of one-way data transmission over simple wireless channels characteristic of many sensing and monitoring applications. Using a specific project as an example, we demonstrate how the constraints of a low-cost embedded wireless system get in the way of a workable solution precluding the use of popular schemes based on windows and periodic acknowledgments. We also propose an efficient solution to the problem and demonstrate its advantage over the traditional protocols.

Document type: 
Article

Robust Nash Dynamic Game Strategy for User Cooperation Energy Efficiency in Wireless Cellular Networks

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2012
Abstract: 

Recently, there is an emerging trend of addressing “energy efficiency” aspect of wireless communications. It has been shown that cooperating users relay each other's information to improve data rates. The energy is limited in the wireless cellular network, but the mobile users refuse to relay. This paper presents an approach that encourages user cooperation in order to improve the energy efficiency. The game theory is an efficient method to solve such conflicts. We present a cellular framework in which two mobile users, who desire to communicate with a common base station, may cooperate via decode-and-forward relaying. In the case of imperfect information assumption, cooperative Nash dynamic game is used between the two users' cooperation to tackle the decision making problems: whether to cooperate and how to cooperate in wireless networks. The scheme based on “cooperative game theory” can achieve general pareto-optimal performance for cooperative games, and thus, maximize the entire system payoff while maintaining fairness.

Document type: 
Article

Discrete Artificial Bee Colony for Computationally Efficient Symbol Detection in Multidevice STBC MIMO Systems

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2013
Abstract: 

A Discrete Artificial Bee Colony (DABC) is presented for joint symbol detection at the receiver in a multidevice Space-Time Block Code (STBC) Mutli-Input Multi-Output (MIMO) communication system. Exhaustive search (maximum likelihood detection) for finding an optimal detection has a computational complexity that increases exponentially with the number of mobile devices, transmit antennas per mobile device, and the number of bits per symbol. ABC is a new population-based, swarm-based Evolutionary Algorithms (EA) presented for multivariable numerical functions and has shown good performance compared to other mainstream EAs for problems in continuous domain. This algorithm simulates the intelligent foraging behavior of honeybee swarms. An enhanced discrete version of the ABC algorithm is presented and applied to the joint symbol detection problem to find a nearly optimal solution in real time. The results of multiple independent simulation runs indicate the effectiveness of DABC with other well-known algorithms previously proposed for joint symbol detection such as the near-optimal sphere decoding, minimum mean square error, zero forcing, and semidefinite relaxation, along with other EAs such as genetic algorithm, estimation of distributions algorithm, and the more novel biogeography-based optimization algorithm.

Document type: 
Article

The RSU Access Problem Based on Evolutionary Game Theory for VANET

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2013
Abstract: 

We identify some challenges in RSU access problem. There are two main problems in V2R      communication. (1) It is difficult to maintain the end-to-end connection between vehicles and RSU due to the high mobility of vehicles. (2) The limited RSU bandwidth resources lead to the vehicles’ disorderly competition behavior, which will give rise to multiple RSUs having overlap area environment where RSU access becomes crucial for increasing vehicles’ throughput. Focusing on the problems mentioned above, the RSU access question in the paper is formulated as a dynamic evolutionary game for studying the competition of vehicles in the single community and among multiple communities to share the limited bandwidth in the available RSUs, and the evolutionary equilibrium evolutionary stable strategy (ESS) is considered to be the solution to this game. Simulation results based on a realistic vehicular traffic model demonstrate the evolution process of the game and how the ESS can affect the network performance.

Document type: 
Article

Error Concealment for 5/3 Motion Compensated Temporal Filtering with Lifting

Author: 
Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2007-10-09
Abstract: 

5/3 Motion Compensated Temporal Filtering (MCTF) is a tool for highly scalable video coding which has been recently studied by many researchers. This thesis presents several error concealment algorithms for 5/3 MCTF with lifting, which can be used to improve the quality of compressed video damaged by packet losses. In MCTF video, the low frequency subband frame, abbreviated as L-frame, contains most of the signal energy in any given Group-of-Pictures (GOP). We assume that one of these L-frames is lost. The proposed error concealment algorithms use the available data to reconstruct the missing L-frame. The simplest error concealment method considered in the thesis is Zero Motion Error Concealment. This method simply assumes zero motion through the damaged GOP, and averages the neighboring L-frames to reconstruct the missing L-frame. Another method called Motion Concatenation finds temporal pathways through the damaged GOP by connecting motion vectors available at the decoder, and copies the corresponding pixel values from the neighboring L-frames to the missing L-frame. Finally, Motion Re-estimation uses motion estimator at the decoder to find a motion vectors between two neighboring L-frames of the missing L-frame, and synthesizes the missing L-frame halfway between its neighboring L-frames. The overall error concealment system combines these three methods to maximize visual performance, as well as the Peak Signal-to-Noise-Ratio (PSNR).

Document type: 
Thesis
File(s): 
Senior supervisor: 
Ivan V. Bajic
Department: 
School of Engineering Science
Thesis type: 
BASc

Comparison of Regression Models for Estimation of Isometric Wrist Joint Torques Using Surface Electromyography

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2011
Abstract: 

Background: Several regression models have been proposed for estimation of isometric joint torque using surfaceelectromyography (SEMG) signals. Common issues related to torque estimation models are degradation of modelaccuracy with passage of time, electrode displacement, and alteration of limb posture. This work compares theperformance of the most commonly used regression models under these circumstances, in order to assistresearchers with identifying the most appropriate model for a specific biomedical application.Methods: Eleven healthy volunteers participated in this study. A custom-built rig, equipped with a torque sensor,was used to measure isometric torque as each volunteer flexed and extended his wrist. SEMG signals from eightforearm muscles, in addition to wrist joint torque data were gathered during the experiment. Additional data weregathered one hour and twenty-four hours following the completion of the first data gathering session, for thepurpose of evaluating the effects of passage of time and electrode displacement on accuracy of models. AcquiredSEMG signals were filtered, rectified, normalized and then fed to models for training.Results: It was shown that mean adjusted coefficient of determination (R2a) values decrease between 20%-35% fordifferent models after one hour while altering arm posture decreased mean R2avalues between 64% to 74% fordifferent models.Conclusions: Model estimation accuracy drops significantly with passage of time, electrode displacement, andalteration of limb posture. Therefore model retraining is crucial for preserving estimation accuracy. Data resamplingcan significantly reduce model training time without losing estimation accuracy. Among the models compared,ordinary least squares linear regression model (OLS) was shown to have high isometric torque estimation accuracycombined with very short training times.

Document type: 
Article

A Preliminary Investigation Assessing the Viability of Classifying Hand Postures in Seniors

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2011
Abstract: 

Background: Fear of frailty is a main concern for seniors. Surface electromyography(sEMG) controlled assistive devices for the upper extremities could potentially be usedto augment seniors’ force while training their muscles and reduce their fear of frailty.In fact, these devices could both improve self confidence and facilitate independentleaving in domestic environments. The successful implementation of sEMG controlleddevices for the elderly strongly relies on the capability of properly determining seniors’actions from their sEMG signals. In this research we investigated the viability ofclassifying hand postures in seniors from sEMG signals of their forearm muscles.Methods: Nineteen volunteers, including seniors (70 years old in average) andyoung people (27 years old in average), participated in this study and sEMG signalsfrom four of their forearm muscles (i.e. Extensor Digitorum, Palmaris Longus, FlexorCarpi Ulnaris and Extensor Carpi Radialis) were recorded. The feature vectors werebuilt by extracting features from each channel of sEMG including autoregressive (AR)model coefficients, waveform length and root mean square (RMS). Multi-classsupport vector machines (SVM) was used as a classifier to distinguish between fifteendifferent essential hand gestures including finger pinching.Results: Classification of hand gestures both in the pronation and supination positionsof the arm was possible. Classified hand gestures were: rest, ulnar deviation, radialdeviation, grasp and four different finger pinching configurations. The obtained averageclassification accuracy was 90.6% for the seniors and 97.6% for the young volunteers.Conclusions: The obtained results proved that the pattern recognition of sEMGsignals in seniors is feasible for both pronation and supination positions of the armand the use of only four EMG channel is sufficient. The outcome of this studytherefore validates the hypothesis that, although there are significant neurologicaland physical changes occurring in humans while ageing, sEMG controlled handassistive devices could potentially be used by the older people.

Document type: 
Article

Two-Way Relaying Using Constant Envelope Modulation and Phase-Superposition-Phase-Forward

Author: 
Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2011
Abstract: 

In this article, we propose the idea of phase-superposition-phase-forward (PSPF) relaying for 2-way 3-phasecooperative network involving constant envelope modulation with discriminator detection in a time-selectiveRayleigh fading environment. A semi-analytical expression for the bit-error-rate (BER) of this system is derived andthe results are verified by simulation. It was found that, compared to one-way relaying, 2-way relaying with PSPFsuffers only a moderate loss in energy efficiency (of 1.5 dB). On the other hand, PSPF improves the transmissionefficiency by 33%. Furthermore, we believe that the loss in transmission efficiency can be reduced if power isallocated to the different nodes in this cooperative network in an ‘optimal’ fashion. To further put the performanceof the proposed PSPF scheme into perspective, we compare it against a phase-combining phase-forwardtechnique that is based on decode-and-forward (DF) and multi-level CPFSK re-modulation at the relay. It wasfound that DF has a higher BER than PSPF and requires additional processing at the relay. It can thus beconcluded that the proposed PSPF technique is indeed the preferred way to maintain constant envelope signalingthroughout the signaling chain in a 2-way 3 phase relaying system.

Document type: 
Article