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Wnuk K.,Lund University | Svensson R.B.,Lund University | Callele D.,TRLabs.
2012 2nd IEEE International Workshop on Requirements Engineering for Systems, Services, and Systems-of-Systems, RESS 2012 - Proceedings | Year: 2012

One of the goals of requirements engineering is to capture and document innovation in the form of new product requirements. These product requirements need to express new system functions or new qualities that are most desired by customers while maintaining customer familiarity with existing products. This paper explores the contradiction between the customer desire for revolutionary advancement and their desire to maintain familiarity with existing systems. This customer inertia creates a bias toward incremental (evolutionary) advancement, potentially multiplying the risks associated with revolutionary innovations. We present a review of scenarios illustrating this stakeholder bias and propose a research agenda for further work in the area. © 2012 IEEE.

Gilmore C.,TRLabs | Zakaria A.,University of Manitoba | Lovetri J.,University of Manitoba | Pistorius S.,University of Manitoba
Medical Physics | Year: 2013

Purpose: Effective imaging of human tissue with microwave tomography systems requires a matching fluid to reduce the wave reflections at the tissue boundary. Further, in order to match the idealized mathematical model used for imaging with the complicated physical measurement environment, loss must be added to the matching fluid. Both too little and too much loss result in low-quality images, but due to the nonlinear nature of the imaging problem, the exact nature of loss-to-image quality cannot be predicted a priori. Possible optimal loss levels include a single, highly sensitive value, or a broad range of acceptable losses. Herein, the authors outline a process of determining an appropriate level of loss inside the matching fluid and attempt to determine the bounds for which the images are the highest quality. Methods: Our biomedical microwave tomography system is designed for 2D limb imaging, operating from 0.8 to 1.2 GHz. Our matching fluid consists of deionized water with various levels of loss introduced by the addition of table salt. Using two homogeneous tissue-mimicking phantoms, and eight different matching fluids of varying salt concentrations, the authors introduce quantitative image quality metrics based on L-norms, mean values, and standard deviations to test the tomography system and assess image quality. Images are generated with a balanced multiplicative regularized contrast source inversion algorithm. The authors further generate images of a human forearm which may be analyzed qualitatively. Results: The image metrics for the phantoms support the claim that the worst images occur at the extremes of high and low salt concentrations. Importantly, the image metrics show that there exists a broad range of salt concentrations that result in high-quality images, not a single optimal value. In particular, 2.5-4.5 g of table salt per liter of deionized water provide the best reconstruction quality for simple phantoms. The authors argue that qualitatively, the human forearm data provide the best images at approximately the same salt concentrations. Conclusions: There exists a relatively large-range of matching fluid losses (i.e., salt concentrations) that provide similar image quality. In particular, it is not necessary to spend time highly optimizing the level of loss in the matching fluid. © 2013 American Association of Physicists in Medicine.

Mousavi P.,TRLabs | Mousavi P.,University of Alberta
IEEE Transactions on Antennas and Propagation | Year: 2011

The concept, design procedure, and measurement results of a novel low profile integrated monopole slots antenna for multiband multipolarization applications are presented. The antenna operates at both GPS and Iridium frequencies of 1.575 GHz and 1.62 GHz with circular polarization and GSM850/GSM900/DCS/PCS bands with a vertical linear polarization. The antenna meets stringent requirements on pattern/polarization performance in all bands. The antenna structure is based on an L-shaped monopole slot with a C-shaped feed to generate a wideband circular polarization. With the integration of two monopole slots inside this structure, the antenna covers quad-band GSM. The integrated monopole slots antenna occupies half of the area on the corner of a circuit board compared to a half-wavelength slot antenna that requires a larger area at the center of the board. This is an attractive feature for compact low frequency telematics devices, whose circuit board floor planning and signal routing are major concerns. © 2011 IEEE.

Phunchongharn P.,University of Manitoba | Hossain E.,University of Manitoba | Le L.B.,University of Québec | Camorlinga S.,Trlabs
IEEE Transactions on Wireless Communications | Year: 2012

We study the robust transmission scheduling and power control problem for spectrum sharing between secondary and primary users in a spatial reuse time-division multiple access (STDMA) network. The objective is to find a robust minimum-length schedule for secondary users (in terms of time slots) subject to the interference constraints for primary users and the traffic demand of secondary users. We consider the fact that power allocation based on average (or estimated) link gains can be improper since actual link gains can be different from the average link gains. Therefore, transmission of the secondary links may fail and require more time slots. We also consider this demand uncertainty arising from channel gain uncertainty. We propose a column generation-based algorithm to solve the scheduling and power control problem for secondary users. The column generation method breaks the problem down to a restricted master problem and a pricing problem. However, the classical column generation method can have convergence problem due to primal degeneracy. We propose an improved column generation algorithm to stabilize and accelerate the column generation procedure by using the perturbation and exact penalty methods. Furthermore, we propose an efficient heuristic algorithm for the pricing problem based on a greedy algorithm. For the simulation scenario considered in this paper, the proposed stabilized column generation algorithm can obtain the optimal schedules with 18.85% reduction of the number of iterations and 0.29% reduction of the number of time slots. Also, the heuristic algorithm can achieve the optimality with 0.39% of cost penalty but 1.67 × 10 4 times reduction of runtime. © 2002-2012 IEEE.

Chieochan S.,University of Manitoba | Hossain E.,University of Manitoba | Diamond J.,TRLabs
IEEE Communications Surveys and Tutorials | Year: 2010

Efficient channel assignment is crucial for successful deployment and operation of IEEE 802.11-based WLANs. In this article we present a survey on the state of the art channel assignment schemes in IEEE 802.11-based WLANs. After detailing out all the schemes, we provide a qualitative comparison among different schemes in terms of algorithm execution behaviors, complexity, and scalability. We then conclude the survey with several research issues open for further investigation. © 2010 IEEE.

Mousavi P.,TRLabs | Miners B.,Intelligent Mechatronic Systems | Basir O.,Intelligent Mechatronic Systems
IEEE Antennas and Wireless Propagation Letters | Year: 2010

A wideband circularly polarized L-shaped monopole slot antenna with a single C-shaped feed is designed and fabricated. The measured results demonstrate that the antenna has an axial ratio (AR) < dB, a reflection coefficient <-10 dB, and 23% circular polarization (CP) bandwidth. The monopole quarter-wavelength slot antenna design occupies half of the area on the corner of circuit board as compared to a half-wavelength slot antenna thatrequires double the area at the center of the board. This feature is attractive for compact wireless devices that operate at low frequencies in which planning for the smallest circuit board area combined with the shortest length for signal routing are the two major concerns. The antenna is extremely low-cost and does not require any truncation corner, reflector surfaces, or via connections, all of which increase the fabrication cost. © 2010 IEEE.

Phunchongharn P.,University of Manitoba | Hossain E.,University of Manitoba | Camorlinga S.,TRLabs
IEEE Transactions on Information Technology in Biomedicine | Year: 2011

We study the multiple access problem for e-Health applications (referred to as secondary users) coexisting with medical devices (referred to as primary or protected users) in a hospital environment. In particular, we focus on transmission scheduling and power control of secondary users in multiple spatial reuse time-division multiple access (STDMA) networks. The objective is to maximize the spectrum utilization of secondary users and minimize their power consumption subject to the electromagnetic interference (EMI) constraints for active and passive medical devices and minimum throughput guarantee for secondary users. The multiple access problem is formulated as a dual objective optimization problem which is shown to be NP-complete. We propose a joint scheduling and power control algorithm based on a greedy approach to solve the problem with much lower computational complexity. To this end, an enhanced greedy algorithm is proposed to improve the performance of the greedy algorithm by finding the optimal sequence of secondary users for scheduling. Using extensive simulations, the tradeoff in performance in terms of spectrum utilization, energy consumption, and computational complexity is evaluated for both the algorithms. © 2011 IEEE.

Shrestha B.,University of Manitoba | Hossain E.,University of Manitoba | Camorlinga S.,TRLabs.
IEEE Transactions on Information Technology in Biomedicine | Year: 2011

In wireless personal area networks, such as wireless body-area sensor networks, stations or devices have different bandwidth requirements and, thus, create heterogeneous traffics. For such networks, the IEEE 802.15.4 medium access control (MAC) can be used in the beacon-enabled mode, which supports guaranteed time slot (GTS) allocation for time-critical data transmissions. This paper presents a general discrete-time Markov chain model for the IEEE 802.15.4-based networks taking into account the slotted carrier sense multiple access with collision avoidance and GTS transmission phenomena together in the heterogeneous traffic scenario and under nonsaturated condition. For this purpose, the standard GTS allocation scheme is modified. For each non-identical device, the Markov model is solved and the average service time and the service utilization factor are analyzed in the non-saturated mode. The analysis is validated by simulations using network simulator version 2.33. Also, the model is enhanced with a wireless propagation model and the performance of the MAC is evaluated in a wheelchair body-area sensor network scenario. © 2006 IEEE.

Onguetou D.P.,TRLabs | Grover W.D.,University of Alberta
Journal of Networks | Year: 2010

This paper shows that, viewed in a generalized "two-hop" framework for node failure recovery, p-cycles actually have a very high inherent ability to restore paths transiting through a failed node. We also showed that with relatively little, if any, extra spare capacity, the principle is also amenable to explicit design of networks for 100% node and span failure protection with a single efficient set of pcycles that support both functions. This is very different than the often-prevailing assumption that "ordinary" pcycles offer no node protection, or only the same nodeprotection as a BLSR ring embodies. Indeed, the two-hop paradigm for recovery of affected paths transiting failed nodes could provide an attractive option for future network operators in that "ordinary" p-cycles are more localized, fast acting, and simple to plan and operate than any other option such as NEPCs, flow-protecting p-cycles or FIPPs. © 2010 Academy Publisher.

Onguetou D.P.,TRLabs | Onguetou D.P.,University of Alberta | Grover W.D.,TRLabs | Grover W.D.,University of Alberta
Computer Communications | Year: 2011

The cost and complexity of wavelength assignment, wavelength conversion and wavelength-selective switching are always of primary considerations in the design of survivable optical networks. This proposal recognizes that as long as the loss budgets are adequate, entire DWDM wavebands could be restored with no switching or manipulation of individual lightpaths; so that the DWDM layer would never know the break happened. And environments where fiber switching devices are low cost, and ducts are full of dark fibers provide a very low cost alternative to protect an entire DWDM transport layer (or working capacity envelope) against the single largest cause of outage. Yet, while nodes and single DWDM channels may fail, a pre-dominant source of unavailability is the physical damage of optical cables. Thus, with the objectives of reducing the overall real CapEx costs and removing the complexity due to wavelength assignment and wavelength continuity constraints when configuring p-cycles in a fully transparent network context, this paper addresses the subsequent questions: if it is ultimately glass that fails, what if just the glass is directly replaced? More specifically, what if p-cycles were used to rapidly, simply and efficiently provide for the direct replacement of failed fiber sections with whole replacement fibers? © 2011 Elsevier B.V. All rights reserved.

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