WINSYS 2009 Abstracts

Area 1 - Wireless Information Networks
Full Papers Short Papers
Area 2 - Wireless Networking Technologies
Full Papers Short Papers
Area 3 - Mobile Software and Services
Full Papers Short Papers

Area 1 - Wireless Information Networks

Full Papers
Paper Nr: 18
Title:

USING SYNCHRONIZED LIGHTWEIGHT STATE OBSERVERS TO MINIMISE WIRELESS SENSOR RESOURCE UTILISATION
Authors:

David Lowe, Steve Murray and Xiaoying Kong
Abstract: A major trend in the evolution of the Web is the rapidly growing numbers of web-enabled sensors which provide a rich ability to monitor and control our physical environment. The devices are often cheap, lightweight, rapidly deployed and densely interconnected. The current dominant models of Web-based data monitoring are not well-adapted to the operational needs of these devices, particularly in terms of resource utilization. In this paper we describe an approach to the optimization of the resources utilized by these devices based on the use of synchronized state-observers. By embedding state observers with a minimized footprint into both the sensors and the monitoring Web client, we show that it is possible to minimize the utilization of limited sensor resources such as power and bandwidth, and hence to improve the performance and potential applications of these devices.
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Short Papers
Paper Nr: 28
Title:

REDUCTION OF INTERFERENCES TO ADJACENT NETWORKS BY COMBINED LATTICE STRUCTURES AND SHRUB BARRIERS
Authors:

Iñigo Cuiñas, Manuel García Sánchez, Ana Vázquez Alejos, José E. Acuña and Paula Gómez
Abstract: The increasing number of wireless LANs using the same spectrum allocation could induce multiple interferences and it also could force the active LANs to continuously retransmit data to solve this problem, overloading the spectrum bands as well as collapsing their own transmission capacity. This upcoming problem can be mitigated by using different techniques, being site shielding one of them. If radio systems could be safeguarded against radiation from transmitter out of the specific network, the frequency reuse is improved and, as a consequence, the number of WLANs sharing the same area may increase maintaining the required quality standards. The proposal of this paper is the use of combined barriers constructed by bushes, supported by lattice structures, in order to attenuate signals from other networks and, so that, to defend the own wireless system from outer interferences. A measurement campaign has been performed in order to test this application of vegetal elements. This campaign was focused on determining the attenuation induced in the propagation channel by several configurations that combine six specimen of Ficus elastica and six structures made of four different materials. The wind effect on the canopies is also considered. Then, the relation between the induced attenuation and the interference from adjacent networks has been computed in terms of separation between networks. The network protection against outer unauthorised access could be also improved by means of the proposed technique.
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Paper Nr: 30
Title:

Indoor Wireless Localisation Network Using A Dynamic Position Tracking Model
Authors:

Montserrat Ros, Joshua Boom and Matthew D'Souza
Abstract: There has been great interest in using position location systems for indoor environments. Indoor environments present many challenges to using wireless localisation systems, due to the interference caused by metal beams and walls present. A variety of position localisation systems have been developed that use wireless channel propagation characteristics, such as receive signal strength to localise a user’s position. We present an inexpensive and robust wireless localisation network that can track the location of users in an indoor environment. The localisation network uses the Zigbee/802.15.4 wireless communications protocol. Reference nodes are placed at known positions in a building. The reference nodes are used by mobile nodes, carried by users to localise their position. Our localisation network also uses a dynamic position tracking model to improve the realtime tracking of mobile nodes. Further work involves improving the dynamic position tracking model by incorporating the use of motion sensors to aid tracking and to investigate how large numbers of active users can be supported.
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Paper Nr: 32
Title:

An Architecture for Environmental Monitoring and Control in Municipal Scale
Authors:

Felipe Pires, Rodrigo Miani and Leonardo Mendes
Abstract: Advances in smart sensors, communication technologies and embedded computing allow to have an interaction between digital and physical worlds. This paper presents an architecture of combining ZigBee with Metropolitan broadband access networks in order to build an architecture for monitoring and control in a municipal scale. A prototype alarm system was implemented based on this architecture as a proof of concept. However there is a wider range of applications that can be designed using this architecture to provide reliable services for government and communities.
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Paper Nr: 41
Title:

Applying Load balance to reduce the energy consumption of the virtual routing protocol
Authors:

Angelo Bannack and Luiz Carlos Pessoa Albini
Abstract: Energy consumption is a key issue in mobile ad hoc networks.To reduce the energy consumption of the network interface, it is necessary to turn it off, immediately affecting the routing protocols. Therefore, routing protocols and energy saving algorithms must be designed to work within each other. This article presents the use of energy management, using the load balance technique with single path, over the Virtual Routing Protocol (VRP). VRP is a hybrid routing protocol that can achieve a high delivery ratio, though it has a high energy consumption. Using load balance, it is possible to minimize this drawback, while keeping the high delivery ratio from VRP. It is shown that the basic VRP consumes more energy than AODV and DSR. While using the load balance technique, the energy consumption of VRP becomes very similar to AODV and DSR.
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Paper Nr: 48
Title:

IMPLICATIONS FOR PRACTICAL WIRELESS SENSOR NETWORKS: UNIQUE OPERATING SYSTEM ARCHITECTURE AND TRANSCEIVER STANDARDS
Authors:

David Border
Abstract: Hallmarks of Wireless Sensor Networks (WSN) include their use in demanding environment, autonomous and untethered operation, low power requirements, miniaturization and low costs. Such hallmarks led to the understandable requirement that WSN sensors contain a specialized microprocessor unit; an innovative microcontroller unit which is strikingly dissimilar to general purpose CPUs found in the marketplace today. This paper examines two important aspects of current sensor node development work, that of microcontroller Operating System (OS) architectures and transceiver standards. The choices of OS designs are intended to match and complement the usefulness of the sensor node itself, while meeting hardware constraints (e.g. memory limitations). The paper details these design choices and how they are being met. Of equal interest, the paper discusses how the choice of transceiver standards for the WSN is determined by the overall design goal of device autonomy. One such “device autonomy discussion topic” relates to the reader how device power consumption levels are being reduced through the use of a newly developed transceiver standard.
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Paper Nr: 50
Title:

INDOOR WIRELESS LOCALISATION NETWORK USING A MOBILE PHONE INTERFACE
Authors:

Matthew D'Souza, Montserrat Ros and Adam Postula
Abstract: In recent years, indoor localisation and movement tracking of people and objects has generated interest for a variety of applications ranging from transport to health care. We present a localisation network designed to track people in an indoor environment. The localisation network consists of static nodes placed at predetermined locations in a building. Users carry a mobile node to track their current position. The mobile node has onboard motion sensors to detect a person’s heading direction and motion state. A dynamic tracking mode was used to determine a person’s position. The dynamic tracking model was implemented using a Multi-Hypothesis Estimation algorithm. The dynamic tracking model determines the mobile node’s position by using the mobile node’s proximity to static nodes, mobile node’s motion sensor information and the building’s floor-plan. We found that by using a multi-hypothesis estimation algorithm, robust localisation accuracy, could be achieved in real-time. The position resolution of the localisation network was found to have a maximum error between 1m and 3.5m. Further work involves extensive testing the localisation network with multiple mobile nodes and over a larger test region. Other areas involve investigating how multiple mobile nodes placed on a user can be used to improve the estimate of the user’s position.
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Paper Nr: 12
Title:

AN ENERGY-AWARE AND COVERAGE-PRESERVING HIERARCHICAL ROUTING PROTOCOL FOR WIRELESS SENSOR NETWORKS
Authors:

Tzu-Shiang Lin, Cheng-Long Chuang, Chia-Pang Chen, Chwan-Lu Tseng, En-Cheng Yang, Chi-Shan Yu and Joe-Air Jiang
Abstract: Coverage-preserving and lifetime-prolonging are essential issues for wireless sensor networks (WSNs). Providing full sensing coverage in a security-sensitive area is necessary for practical applications such as security surveillances or military investigations. In order to prolong the duration of full sensing coverage, we propose an Energy-aware and Coverage-presenting Hierarchical Routing (ECHR) protocol for randomly deployed WSNs. The proposed ECHR protocol uses the multi-hop transmission to reduce the energy consumption for transmitting data between sensor nodes and the cluster head selected by the ECHR protocol. The ECHR protocol accommodates energy-balancing and coverage-preserving while selecting one cluster head for each round. The power consumption of radio transmission and residual energy over the network are taken into account when determining an optimal route for a packet. The simulation results show that ECHR prolongs the duration with full sensing coverage, which provides up to 85% extra lifetime comparing with other protocols.
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Paper Nr: 16
Title:

A Content-driven data propagation protocol for Mobile Social Network in disconnected MANETs
Authors:

Basit Qureshi, Geyong Min and Demetres Kouvatsos
Abstract: Abstract: Recently various architectures for Mobile Social Networks (MSNs) have been proposed. In MSNs users can participate in communication with other users based on their respective interest profiles with the idea of sharing documents that are of interest to a particular user. Typically users subscribe to a social networking service and look for other users with similar interest profiles. However connectivity may not always be available for sharing data. In this paper we propose a protocol for MSN implementation in a disconnected Mobile Ad Hoc Network environment for sharing data. Message delivery in disconnected Mobile Ad Hoc networks (MANETs) is difficult since the network graph is rarely connected. Our proposed protocol exploits the store, carry and forward capability of a disconnected MANET. Results from simulations and implementation show that this approach efficiently disseminates data while minimizing use of resources in the network.
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Paper Nr: 34
Title:

SELF-DESTRUCTION PROCEDURE FOR CLUSTER-TREE WIRELESS SENSOR NETWORKS
Authors:

Madalin Plastoi, Daniel Ioan Curiac, Ovidiu Banias, Constantin Volosencu, Dan Pescaru and Alex Doboli
Abstract: Wireless sensor networks (WSN) are rapidly expanding their attractiveness in both military and civilian applications, imposing the need for effective security strategies/mechanisms. In this paper we considered that a new phase (self-destruction) must be included as a final stage in the WSN lifecycle in order to assure the confidentiality regarding information like: network topology, type of measurement data gathered by sensors, encryption/authentication algorithms and key-exchange mechanisms, etc. that can be unveiled through reverse engineering methods. Moreover, we presented a new procedure that implements this new lifecycle phase on a cluster-tree network topology.
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Area 2 - Wireless Networking Technologies

Full Papers
Paper Nr: 9
Title:

Modulation-Mode Assignment in SVD-assisted Broadband MIMO-BICM Schemes
Authors:

Andreas Ahrens and César Benavente-Peces
Abstract: In this contribution we jointly optimize the number of activated MIMO layers and the number of bits per symbol under the constraint of a given fixed data throughput and integrity. In analogy to bit-interleaved coded irregular modulation, we introduce a Broadband MIMO-BICM scheme, where different signal constellations and mappings were used within a single codeword. Extrinsic information transfer (EXIT) charts are used for analyzing and optimizing the convergence behaviour of the iterative demapping and decoding. Our results show that in order to achieve the best bit-error rate, not necessarily all MIMO layers have to be activated.
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Short Papers
Paper Nr: 8
Title:

Modulation-Mode and Power Assignment in SVD-assisted Broadband MIMO Systems
Authors:

Andreas Ahrens and César Benavente-Peces
Abstract: Existing bit loading and transmit power allocation techniques are often optimized for maintaining both a fixed transmit power and a fixed target bit-error rate while attempting to maximize the overall data-rate. However, delay-critical real-time interactive applications, such as voice or video transmission, may require a fixed data rate. For these fixed-rate applications it is desirable to design algorithms, which minimize the bit-error rate (BER) at a given fixed data rate. Since the capacity of multiple-input multiple-output (MIMO) systems increases linearly with the minimum number of antennas at both, the transmitter as well as the receiver side, MIMO schemes have attracted a lot of attention. However, non-frequency selective MIMO links have reached a state of maturity. By contrast, frequency selective MIMO links require substantial further research, leading in this contribution to a joint optimization of the number of activated MIMO layers and the number of bits per symbol along with the appropriate allocation of the transmit power under the constraint of a given fixed data throughput. Our results show that in order to achieve the best possible bit-error rate, not necessarily all MIMO layers have to be activated.
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Paper Nr: 19
Title:

FIXED POINT SVD COMPUTATION ERROR CHARACTERIZATION AND PERFORMANCE LOSSSES IN MIMO SYSTEMS
Authors:

César Benavente-Peces, Fco. Javier Ortega-González, José M. Pardo-Martín and Andreas Ahrens
Abstract: This paper is devoted to analyze the error met when computing the singular value decomposition (SVD) of the gain channel matrix in a MIMO communication system and using fixed-point arithmetic for the calculations. The study is focused in the case of the SVD implementation for modulation-mode and power assignment in non-frequency selective MIMO systems using efficient algorithms and flexible hardware platforms, and M-ary Quadrature Amplitude Modulation (QAM). It is demonstrated that not necessarily all MIMO layers must be activated. The combination of the CORDIC algorithm and look-up tables seems to be a good solution for this task since it can efficiently compute the singular value decomposition. The paper highlights the characterization of computation errors and shows the performance losses produced by the use of approximations in the eigenvalues and eigenvectors calculation, including the effects produced in the power assignment process.
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Paper Nr: 22
Title:

A CONTRIBUTION TO LABORATORY PERFORMANCE COMPARISONS OF IEEE 802.11 B,G POINT-TO-POINT LINKS
Authors:

José A. R. Pacheco de Carvalho, Hugo Veiga, N. Marques, C. F. Ribeiro Pacheco and P. A. J. Gomes
Abstract: The importance of wireless communications has been growing. Performance is a very relevant issue, leading to more reliable and efficient communications. Laboratory measurements are made about several performance aspects of Wi-Fi (IEEE 802.11 b, g) point-to-point links. A contribution is given to evaluation of this technology through performance comparisons, using available access points from Enterasys Networks and Linksys. Detailed results are presented and discussed, namely at OSI levels 4 and 7, from experiments involving TCP, UDP and FTP: TCP throughput, jitter, percentage datagram loss and FTP transfer rate.
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Paper Nr: 29
Title:

SHORT RANGE ULTRASONIC COMMUNICATIONS IN AIR USING QUADRATURE MODULATION
Authors:

Chuan Li, David Hutchins and Roger Green
Abstract: A study has been undertaken of ultrasonic communications methods in air, using a quadrature modulation method. Simulations were first performed in order to establish the likely performance of Quadrature Phase Shift Keying (QPSK) over the limited bandwidth available in an ultrasonic system. QPSK modulation was then implemented within an experimental communication system, using capacitive ultrasonic sources and receivers. The results show that such a system is feasible in principle for communications over distances of several metres, using frequencies in the 200-400 kHz range. Data rate is typically at 200 kbps.
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Paper Nr: 42
Title:

Sequential Symbol Synchronizers based on Pulse Comparation
Authors:

Antonio Reis, Atilio Gameiro, José A. R. Pacheco de Carvalho and Jose Rocha
Abstract: This work presents a sequential symbol synchronizer, that is based on a pulse comparation, between a phase variable pulse and a reference fixed pulse. This synchronizer has two types namely the both data transitions and the positive data transitions. Each type has two versions which are the manual and the automatic. The objective is to study the synchronizers and evaluate the output jitter UIRMS (Unit Interval Root Mean Square) versus the input SNR (Signal Noise Ratio).
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Paper Nr: 43
Title:

Sequential Symbol Synchronizers based on Clock Sampling
Authors:

Antonio Reis, Atilio Gameiro, José A. R. Pacheco de Carvalho and Jose Rocha
Abstract: This work presents a sequential symbol synchronizer, that was discovered by us, and is based on the clock sampling by the input data transitions. This synchronizer has two types, namely the discrete and the continuous. Each type has two versions which are the manual and the automatic. This synchronizer has an own big advantage, because its manual version adjust hasn’t critical phase. The objective is to study the synchronizers and to evaluate their output jitter UIRMS (Unit Interval Root Mean Square) versus input SNR (Signal to Noise Ratio).
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Paper Nr: 45
Title:

COMPARATIVE PERFORMANCE STUDIES OF WI-FI IEEE 802.11 A,G LABORATORY POINT-TO-POINT LINKS

Authors:

José A. R. Pacheco de Carvalho, Hugo Veiga, N. Marques, C. F. Ribeiro Pacheco, P. A. J. Gomes and Antonio Reis
Abstract: The importance of wireless communications has been growing. Performance is a very relevant issue, leading to more reliable and efficient communications. Laboratory measurements are made about several performance aspects of Wi-Fi (IEEE 802.11 a, g) point-to-point links. A contribution is given to performance evaluation of this technology, using available access points from Enterasys Networks. Detailed results are presented and discussed, namely at OSI levels 4 and 7, from TCP, UDP and FTP experiments: TCP throughput, jitter, percentage datagram loss and FTP transfer rate. Conclusions are drawn about the comparative performance of the links.
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Area 3 - Mobile Software and Services

Full Papers
Paper Nr: 27
Title:

A Token-based Broadcast Algorithm over DHT for Large-scale Computing Infrastructures
Authors:

Kun Huang and Dafang Zhang
Abstract: Scalable and efficient broadcast is essential to the large-scale computing infrastructures such as PlanetLab and Grids. By exploiting the greedy routing mechanisms of Distributed Hash Table (DHT), existing DHT-based broadcast algorithms suffer from the limitations of scalability and load balancing, incurring high construction and maintenance overhead for a distributed broadcast tree (DBT). This paper presents a token-based broadcast algorithm over DHT for the large-scale computing infrastructures, where each node selects the finger nodes as its children by a token value in a top-down approach. Theoretical analysis and experimental results show that the token-based broadcast algorithm can construct and maintain a balanced DBT with low overhead, where the branching factors of each node are at most two, and the tree height is O(logn) in a Chord of n nodes, without any extra storage space and explicit maintenance overhead.
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Paper Nr: 38
Title:

A SELF-CONFIGURING MIDDLEWARE FOR MANAGING CONTEXT AWARENESS

Authors:

Ionut Anghel, Tudor Cioara, Ioan Salomie, Mihaela Dinsoreanu and Anca Rarau
Abstract: This paper introduces a self-configuring middleware that manages the context information acquisition and representation processes targeting the development of context aware applications. The context information is represented using three sets: context resources, actors and policies. The context model management infrastructure is constructed using BDI agents that generate and administrate the context model artefacts at run time. The self – configuring property is enforced by monitoring the real world context in order to detect context variations or conditions for which the context artefacts must be updated. The advantage of our approach is the transparency of the context management processes for the pervasive application developers, allowing them to focus on the application desired functionality. The middleware was tested and validated within the premises of our Distributed Systems Research Laboratory.
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Paper Nr: 49
Title:

Improving directory-less WLAN positioning by device whispering
Authors:

Christoph Terwelp, Janno von Stülpnagel, Karl-Heinz Krempels and Sebastian Patzak
Abstract: Existing positioning systems do not provide the required positioning accuracy for navigation systems in indoor environments. Novel system approaches are based on fingerprinting and triangulation techniques. Thus, they suffer on low positioning accuracy due to multipath propagation and different sending power of the considered access points. Other approaches are based on tagged WLAN~(Wireless Local Area Network) access points or GSM~(Global System for Mobile Communication) base stations with their corresponding position stored in a central tag directory. This would cause high communication costs for a mobile device that queries the directory frequently. In this paper we present a filtering technique for access points to determine the closest ones to the mobile device. The geographical position of the mobile device is calculated from the geo tags broadcasted by the access points in the mobile device's vicinity. Systems based on this approach will provide the same accuracy as directory-based positioning systems at a low cost.
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Short Papers
Paper Nr: 36
Title:

A QOS-BROKER-BASED FRAMEWORK FOR PERSONALIZED WEB SERVICES PROVISIONING TO MOBILE USERS
Authors:

Elarbi Badidi, Larbi Esmahi, Mohamed Adel Serhani and Ikbal Taleb
Abstract: This paper proposes a broker-based Web services provisioning system for mobile users with QoS requirements. It describes a set of cooperative brokers distributed over different sites that work together to provide personalized services for mobile users while they move from one location to another in their corporate and partners’ networks. Access to QoS-enabled Web services is obtained in accordance with the users’ home policies. This is made possible by negotiating the user profile and the terms of the service level agreement.
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Paper Nr: 40
Title:

A CONTEXT-AWARE PLATFORM TO SUPPORT MOBILE USERS WITH PERSONALIZED SERVICES
Authors:

Yousra Bouzid, Hamid Harroud, Abdelaziz Berrado, Mohammed Boulmalf and Ahmed Karmouch
Abstract: The emergence of ubiquitous computing, enabled by the availability of portable devices and advances in (wireless) networking technologies, has increased the need for personalized and adaptive services in mobile environments. Users are not anymore only using computing facilities on their desktop machines in a relatively predefined office environment, but they require having access to various services as they move from one location to another, from one device to another and from one network to another. This paper presents a context-aware platform for supporting mobile users with personalized services. The platform is capable of handling different types of context sources (e.g. sensors, readers, agents), offers sophisticated mechanisms in matching the mobile user’s preferences with services that are available at the visited location, and provides these services in personalized and adaptive manner to the user conditions. As a proof of concept, we deployed an e-tourism prototype on top of the platform that assists tourists during their travels by providing them with context sensitive services and nearby points of interests.
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Paper Nr: 20
Title:

Multimedia Platform for Mobile Tourist Guidance and Services in the cities of Ubeda and Baeza (Spain)
Authors:

Damian Martinez, Pedro Vera, Luis Alcantara and Nicolas Ruiz Reyes
Abstract: In this paper we describe an innovative multimedia system that has been installed in the Spanish cities of Ubeda and Baeza whose Renaissance monumental ensembles has been declared World Heritage by UNESCO. The system offers an advanced information service and tourist guide to the visitors, and ensures that every tourist, just carrying an appropriate commercial mobile phone, gets the right information to enjoy and make the most of his visit in town in a personal manner. The service offered by the system to the user is proactive and personalized, taking into account the specific circumstances affecting each user: exact location, track followed, time and date, mobile terminal employed, etc. The user carries a personal device that becomes a new interface between him or her and the surroundings. The platform detects the presence of the user when he or she gets close to specifically determined location points. As a function of the users’ context (location, time, track, etc.), the system sends them personalized relevant information. This project has been funded by the “Ciudades Digitales” Program of the Ministry of Industry, Junta de Andalucía, Diputación de Jaén and the City Councils of both cities.
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Paper Nr: 21
Title:

Indoor Navigation using approximate Positions
Authors:

Ory Chowaw-Liebman, Christoph Terwelp, Janno von Stülpnagel and Karl-Heinz Krempels
Abstract: Navigation aids have usually concentrated on the great outdoors, whether driving on highways or, more re- cently, walking through cities. These systems use the Global Positoining System (GPS) for position infor- mation. Indoor navigation cannot rely on GPS. In order to provide position information indoors, a technique called device whispering was developed. The following presents an indoor system currently being developed, which is suited to the imprecise position information provided by device whispering.
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Paper Nr: 31
Title:

PROBLEM OF INEFFICIENT INTERNAL HARDWARE OF PORTABLE MOBILE DEVICES Solving by Artifacts Prebuffering using Mobile Database Cache
Authors:

Ondrej Krejcar, Dalibor Janckulik and Leona Motalova
Abstract: The paper deals with a problem of inefficient internal hardware like bus, memory or CPU of wireless connected portable mobile devices and a possibility to solve this problem by a prebuffering of selected artifacts. The basics are in a model of data prebuffering based system enhancement for locating and tracking users inside the buildings. The framework uses a WiFi network infrastructure to let a mobile device determine its indoor position. User location is used for data prebuffering and pushing information from server to user’s PDA. All server data is saved as artifacts (together) with its position information in building. The accessing of prebuffered data on mobile device can highly improve response time needed to view large multimedia data. I tested our solution on created facility management information system with testing collection of about hundred large size artifacts. On mobile device the SQL Server CE database is used as a cache. Finally the new way to manage the artifacts throw the framework is described and tested.
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Paper Nr: 35
Title:

Digital Rights Management as a Service - Developing Towards an Internet Service for Desktop and Mobile Users
Authors:

Shih-Fang Chang
Abstract: In November 2002 the Open Mobile Alliance starts to work out standard protection mechanism on digital content, so-called digital rights management (DRM). Then the OMA DRM 1.0 and 2.0 were approved in June 2004 and March 2006. Lots of industries and companies not only use the technology to protect their own media content, but also make sure the content should be revealed and retrieved in reasonable and secure manner. However, the cost and the availability for operating and integrating the technology would be very huge. Therefore, the proposed system is named DRMaaS that redesign the scenarios, those traditionally DRM technology has, with concept of Software as a Service (SaaS). In addition, we preserve the feasible feature to conjunct with other optional functionalities, like storage service and certification service. The proposed system is a work in progress towards an internet service for both desktop and mobile applications.
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