Papers by Pawel Gburzynski
Lecture Notes in Networks and Systems, 2019
The series "Lecture Notes in Networks and Systems" publishes the latest developments in Networks ... more The series "Lecture Notes in Networks and Systems" publishes the latest developments in Networks and Systems-quickly, informally and with high quality. Original research reported in proceedings and post-proceedings represents the core of LNNS. Volumes published in LNNS embrace all aspects and subfields of, as well as new challenges in, Networks and Systems. The series contains proceedings and edited volumes in systems and networks, spanning the areas of Cyber
ICGST-ACSE Journal, ISSN, 2009
... of the performance of the ultrasonic sensors, the next step involved making design decision r... more ... of the performance of the ultrasonic sensors, the next step involved making design decision regarding the ... Three different indicators were implemented in the prototype system: an LED display panel, two tactile ... as shown in Figure 7. To trigger the buzzer, a square wave of 2400 ...
Protocol Validation is the process of showing that a (suitably specified) protocol has certain (s... more Protocol Validation is the process of showing that a (suitably specified) protocol has certain (suitably specified) properties, for example, that it is free from deadlocks. In the past, the acceptance of automated tools for the validation of protocols has been hindered by three main problems: (1) most validation tools are lacking in the level of realism they support: they are either unable to deal with the timing aspects (e.g., delays between events) or the probabilistic aspects (e.g., probability of loss) of protocols; (2) unlike most performance evaluation tools which are based on common programming languages like C or C++, validation tools often employ special-purpose languages (e.g., PROMELA in S PIN, KRONOS); and (3) protocol validation is computationally difficult due to the state space explosion problem—the fact that the state space of a protocol is exponential in the number of variables and processes. Validation algorithms published in the literature often have unrealistic resource requirements. In this thesis, we propose a validation tool that addresses these problems. Our tool is based on the well-known discrete event simulation (DES) paradigm and checks whether a property expressed in a simple linear-time logic (event logic, (EL)) is satisfied by a protocol. The tool is based on DES and thus supports time and probabilities (problem 1 above). Problem (2) is addressed by implementing the tool as a C++ library. To better deal with the state explosion problem, we propose using state transition probabilities as a heuristic to guide the state space search, and present some memory-efficient algorithms for the checking of EL formulas. An added advantage of our approach is that the same protocol specification can be used for both performance evaluation by simulation and for validation. A number of experiments described in the thesis demonstrate the feasibility of our validation tool.
Rapid progress in computer technology, processor speed and memory capacity, as well as demand for... more Rapid progress in computer technology, processor speed and memory capacity, as well as demand for digital audio and video pose new problems in communication networks. To accommodate a whole range of new applications, the networks must operate at very high speeds, and they often require new protocols. These networks are supposed to employ the connection-oriented paradigm as the only solution that will achieve the desired very high speeds. However, this paradigm, although it does possess certain virtues, is not free from disadvantages that make the effective implementation of such networks difficult. In this dissertation, we study the suitability of a connection-less paradigm in high-speed networks, deflection routing. High-speed isochronous applications, like video, require small deviations from the average interarrival delay (low jitter). We show that deflection networks, equipped with reassembly buffers of modest size, can smooth out the jitter and assure a very low packet loss reg...
We present a system, descending from an event-driven simulator, for verifying probabilistic and t... more We present a system, descending from an event-driven simulator, for verifying probabilistic and timed properties of communication protocols. Our system was inspired by Spin 5, 6, 7], and employs essentially the same eecient technique of state exploration, but it extends those ideas in the direction of expressing properties involving probabilities and strict timing (as opposed to the mere succession of events). This way, our approach is applicable to protocols in which the exact timing of events is critical for their correct operation, e.g., protocols for real-time multimedia applications, access protocols for shared-media networks , or reactive protocols driving distributed real-time equipment.
DS-TDMA/CP is a TDMA-based medium access protocol for cellular networks catering to multiple traf... more DS-TDMA/CP is a TDMA-based medium access protocol for cellular networks catering to multiple traffic classeswith diverseQoS requirements. In contrast to other TDMA protocols for mobile applications, instead of trying to fit the offered traffic to the slot size,our solution adapts the slot sizeto the offered traffic. In consequence, asdemonstrated by our performance studies, the proposedscheme is more flexible and incurs lower bandwidth overhead than other TDMA-based solutions.
We investigate experimentally the performance of de ec tion networks for jitter sensitive tra c I... more We investigate experimentally the performance of de ec tion networks for jitter sensitive tra c It is a com mon belief that pure de ection networks are not suit able for isochronous applications and networks based on a connection oriented paradigm are the only solution in such cases We argue to the contrary and present simulation results supporting our claims
We investigate experimentally the performance of deflection networks for jitter-sensitive traffic... more We investigate experimentally the performance of deflection networks for jitter-sensitive traffic. It is a common belief that pure deflection networks are not suitable for isochronous applications, and networks based on a connection-oriented paradigm are the only solution in such cases. We argue to the contrary and present simulation results supporting our claims.
We present a system for the simulation and validation of communication protocols. Our tool borrow... more We present a system for the simulation and validation of communication protocols. Our tool borrows ideas from Spin Holzmann, 1997], but in addition enables the modeling of timing and probability constraints because it is based on discrete event simulation. We describe a logic for specifying properties of communication protocols, and a model-checking algorithm for calculating the probability of such a property being satissed by the protocol. Using a queueing system as an example, we show that the same model can be used to obtain performance measures by simulation and for model-checking.
International Conference on Internet Computing, 2002
We study the behavior of a Quality of Service (QoS) routing scheme in which connection requests c... more We study the behavior of a Quality of Service (QoS) routing scheme in which connection requests can be assigned to one ofk alternative paths from the source to the destination. The multiple‐path routing compensates for the inaccurate link state (LS) information. It is found that the frequency of LS dissemination is not the only factor to influence performance. For
2010 15th IEEE International Workshop on Computer Aided Modeling, Analysis and Design of Communication Links and Networks (CAMAD), 2010
Urban environments are notorious for their high spectrum usage, particularly in their unlicensed ... more Urban environments are notorious for their high spectrum usage, particularly in their unlicensed radio bands. Wireless sensor network (WSN) nodes incorporate modern transceivers that can measure the background noise/interference and change channels. These combined capabilities suggest the need to better understand urban environments so that nodes can better avoid competing devices. In this paper, we explore the noise and interference patterns found on 256 frequencies in an indoor urban environment's 900 MHz ISM and non-ISM bands. We begin the process by using off-the-shelf WSN hardware to sample the environment at 5 kHz from 16 locations simultaneously. From these samples, we identify five prevalent patterns and then hand-classify the 4096 traces of noise and interference. Finally, we extract a variety of statistics from the traces and use them in a Bayesian network classifier.
ICC 2001. IEEE International Conference on Communications. Conference Record (Cat. No.01CH37240)
Multiple Path Routing in Networks with Inaccurate Link State Informat ion ... Yanxia Jia, Ioanis ... more Multiple Path Routing in Networks with Inaccurate Link State Informat ion ... Yanxia Jia, Ioanis Nikolaidis, Pawel Gburzynski Department of Computing Science University of Alberta Edmonton, Alberta, CANADA T6H 2E8 ... Abstract-We study a collection of K-shortest ...
Winter Simulation Conference Proceedings, 1995.
2007 Canadian Conference on Electrical and Computer Engineering, 2007
This paper introduces an inexpensive car security system which addresses the needs for broader ar... more This paper introduces an inexpensive car security system which addresses the needs for broader area coverage around the vehicle and stronger indication signals to drivers. The new driving assistant features simple ultrasonic-based sensors, implemented at the two front corners and the two blind spots of the vehicle. In order to report the close-by objects to the driver, the system employs a multitude of feedback devices, including tactile vibrators attached to the steering wheel, audible signals, and an LED display mounted on the dash board. The sensor system and the feedback devices are controlled in real-time by microcontrollers over a wireless communication network. The final prototype system was installed and tested on a ride-on toy car.
2010 IEEE International Conference on Communications, 2010
We present a beacon-based clustering algorithm aimed at prolonging the cluster lifetime in VANETs... more We present a beacon-based clustering algorithm aimed at prolonging the cluster lifetime in VANETs. We use a new aggregate local mobility criterion to decide upon cluster re-organisation. The scheme incorporates a contention method to avoid triggering frequent re-organisations when two clusterheads encounter each other for a short period of time. Simulation results show a significant improvement of cluster lifetime and
2009 IEEE International Conference on Communications Workshops, 2009
We present a certain approach to indoor location tracking based on sensing the strength of receiv... more We present a certain approach to indoor location tracking based on sensing the strength of received RF signal. Our scheme employs a database of signal strength readings from known locations collected during a prerequisite profiling stage. Subsequently, the problem of estimating the location of a node emitting an RF signal from an unknown place boils down to data mining in the database-to select a best matched set of profile points and then average the coordinates of those points into an approximate location of the tracked sender. We show preliminary experimental results which confirm our hope that this approach will result in a better accuracy than, e.g., triangulation based schemes.
IEEE 54th Vehicular Technology Conference. VTC Fall 2001. Proceedings (Cat. No.01CH37211), 2001
We present a TDMA-based scheme intended for carrying traffic with diverse QoS requirements in mob... more We present a TDMA-based scheme intended for carrying traffic with diverse QoS requirements in mobile environments. In contrast to other TDMA protocols for mobile applications, instead of trying to fit the offered traffic to the slot size, our solution adapts the slot size to the offered traffic. In consequence, the proposed scheme is more flexible and incurs lower bandwidth overhead than other TDMA-based solutions.
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Papers by Pawel Gburzynski