WINSYS 2008 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: 34
Title:

AN EVALUATION OF A CONSERVATIVE TRANSMIT POWER CONTROL MECHANISM ON AN INDOOR 802.11 WIRELESS MESH TESTBED
Authors:

Karol Kowalik, Marek Bykowski, Brian Keegan and Mark Davis
Abstract: Power control techniques for IEEE 802.11 wireless networks have already gained considerable attention. Such techniques are particularly attractive because they can improve various aspects of wireless network operation such as interference mitigation, spatial reuse in dense wireless deployments, topology control, and link quality enhancement. In this paper we propose a novel delivery ratio based Conservative Transmit Power Control (ConTPC) mechanism. Our implementation is conservative when it comes to deciding if the transmit power should be reduced for a given link. This is because we do not want poor quality wireless links to further reduce their quality and be overwhelmed by other links transmitting at maximum power. We have experimentally evaluated the benefit of the proposed power control scheme when compared with fixed power level systems. We show that our ConTPC mechanism can increase the throughput, however the magnitude of this enhancement largely depends on the topology of the wireless network.
Download
Paper Nr: 49
Title:

FRAME ERROR RATE EVALUATION OF A C-ARQ PROTOCOL WITH MAXIMUM-LIKELIHOOD FRAME COMBINING
Authors:

Julián Morillo and Jorge García
Abstract: In this paper a Cooperative-ARQ (C-ARQ) with a maximum-likelihood frame combiner (ML-FC) protocol is studied. C-ARQ is well suited for wireless transmission in either infrastructure or ad-hoc networks, as it exploits some of the unique characteristics of wireless media, such as the natural broadcast of wireless transmission and receiver diversity. The frame combiner can help in the case in which any received frame is correct, exploiting the same characteristics of wireless transmission but at a bit level. The paper studies the Frame Error Rate for this kind of system, showing that significant improvements can be obtained.
Download
Paper Nr: 75
Title:

PROBABILISTIC RETRANSMISSION STRATEGY FOR SINGLE-RELAY COOPERATIVE ARQ
Authors:

Juan J. Alcaraz, Joan Garcia-haro and Fernando Cerdan
Abstract: In wireless networks with cooperative automatic repeat request (C-ARQ) protocols, a relay node, placed within the range of the sender node and the destination node, assists the sender in the process of frame retransmission. In a collision-free scenario, the sender and the relay use different physical channels for retransmissions. This paper highlights the tradeoff between throughput increment and efficiency in the use of radio resources. By using a probabilistic retransmission strategy, the sender only retransmits in some time-slots after a frame error notification. At the other time-slots, the source can assign the radio resources to other communication processes, resulting in more efficient use of the bandwidth. The retransmission probability must be carefully adjusted according to the network parameters. In this paper we propose a Markov model to compute the throughput performance and a complementary reward model to compute the retransmission rate of the source. In order to keep the throughput at a high value and to reduce the retransmission rate at the same time, we present a multi-objective optimization method that is capable of balancing both objectives in any scenario. It is shown that the increment in bandwidth efficiency can be very high, especially for degraded links, compensating the small throughput reduction associated with a probabilistic retransmission at the source.
Download
Paper Nr: 78
Title:

IMPROVING ENERGY CONSUMPTION IN LARGE SCALE WIRELESS SENSOR NETWORKS WITH MULTIPLE MOBILE SINKS DEPLOYMENT
Authors:

Ines Slama, Badii Jouaber and Djamal Zeghlache
Abstract: In this paper, we consider the multiple sinks placement problem in energy constrained large-scale Wireless Sensor Networks (WSN). First, some fundamental design parameters in WSNs such as nodes deployment, the network architecture, sink velocity and transmission range, are investigated. Each of these parameters is analysed and discussed according to its influence on the energy consumption in a WSN. Second, a simple and efficient approach for the placement of multiple sinks within large-scale WSNs is proposed. The objective is to determine optimal sinks’ positions that maximize the network lifetime by reducing energy consumption related to data transmissions from sensor nodes to different sinks. Balanced graph partitioning techniques are used to split the entire WSN into connected sub-networks. Smaller sub-networks are created, having similar characteristics and where energy consumption can be optimized independently but in the same way. Therefore, different approaches and mechanisms that enhance the network lifetime in small-size WSN can be deployed inside each sub-network. Performance results show that the proposed technique significantly enhances the network lifetime.
Download
Short Papers
Paper Nr: 81
Title:

INTRUSION K-COVERAGE IN WIRELESS SENSOR NETWORKS
Authors:

Amir Yahyavi, Laleh Roostapour, Roohollah Aslanzadeh, Mehdi Dehghan and Naser Yazdani
Abstract: One of the main applications of Wireless Sensor Networks is surveillance and monitoring. Providing and maintaining the required coverage over the area of an intrusion (or other events of our choice) is of great importance. The network should be able to provide different levels of coverage based on application needs and reconfigure itself while ensuring energy efficiency. In this paper we present a dynamic approach to provide asymptotic k-coverage over the area of an intrusion. This is a probabilistic approach which creates full coverage over the surveillance zone and provides k-coverage over the area of an event. Our simulations show that this approach is able to provide the requested coverage while consuming less than a third of the static approaches. Also due to probabilistic nature of this approach communication overhead is much lower than deterministic methods.
Download
Paper Nr: 112
Title:

AUTHENTICATION EMPLOYING NEIGHBOR TABLES IN MOBILE AD HOC NETWORKS
Authors:

Dorsaf Azzabi, Kunihito Tanaka, Ushio Yamamoto and Yoshikuni Onozato
Abstract: In this paper we investigate the authentication mechanism in mobile ad hoc networks (MANET). Developing a trustworthy authentication mechanism in a dynamic and volatile ad hoc mobile setting is a complex task. The goal of this paper is to propose an authentication mechanism to validate the existence of neighborhood in MANET. We focus on common adjacent nodes which can authenticate and trust a mobile node. Simulation results show the existence of common adjacent nodes that are able to establish trust and obtain the effective range of neighbor authentication in terms of transmission range and node density.
Download
Paper Nr: 117
Title:

TOPOLOGICAL DEPENDENCE AND FAULT TOLERANCE IN TDMA BASED POWER CONSERVATION FOR WSNS
Authors:

Dimitrios J. Vergados, Nikolaos A. Pantazis, Dimitrios D. Vergados and Christos Douligeris
Abstract: Energy conservation is a very critical issue in energy-constrained wireless sensor networks that introduces sleep-mode related delay. Since a long time delay can be harmful for either large or small wireless sensor networks, a TDMA-based scheduling scheme has been proposed, that achieves the reduction of the end-to-end delay caused by the sleep mode operation while at the same time it maximizes the energy savings. However, the performance of this system has not been studied with respect to the topology of the network, and taking into consideration node failures. In this paper, we evaluate the TDMA-based energy conservation scheme, and compare it to the S-MAC and the adaptive listening schemes, on various random topologies. In addition, we examine the performance when node failures occur, and introduce a schedule update criterion.
Download
Paper Nr: 24
Title:

CRC-16-BASED COLLISION RESOLUTION IN EPCGLOBAL CLASS1 GENERATION2 RFID SYSTEMS
Authors:

Jun-Bong Eom and Tae-Jin Lee
Abstract: The 900 MHz UHF passive RFID systems have drawn attraction because they have long access distance and rapid identification speed. One of the most representative international standards is EPCglobal Class1 Generation2 (EPCglobal Gen2). RN16 which is used in the EPCglobal Gen2 standard assists a reader to detect tag collision rapidly, but it may be removed because it does not have information of products. In this paper, we propose an algorithm to replace RN16 with CRC-16 to reduce the identification time. We show that CRC-16 has similar characteristics of RN16 and our proposed scheme reduces the number of bits required for one tag identification.
Download
Paper Nr: 32
Title:

CACHING AND SCHEDULING MECHANISMS FOR H.264 VIDEO FLOW DELIVERY OVER DISCONTINUOUS COVERAGE WIRELESS NETWORKS
Authors:

Azza Jedidi, Frédéric Weis, Sylvaine Kerboeuf and Marie-Line Alberi Morel
Abstract: The past few years have witnessed the deployment of a wide variety of multimedia applications over wireless networks. As a consequence, mobile users are demanding fast and efficient connectivity, especially concerning start-up delays and flow quality. Wireless networks aim at providing an everywhere coverage without prohibitive deployment costs. Thus, the coverage of each access point is extended with detriment to the mean throughput of the radio cell. The throughput of each zone decreases non-uniformely from the cell center to the cell edge. The coverage is continuous, but radio conditions met by users are not homogeneous. In fact, the data rate varies according to user mobility. In the context of streaming applications, intermittent high rate availability may lead to service disruption, especially when user number’s increases. Thus, it is essential to design a network architecture able to efficiently deliver video flows to mobile users. In our work, a new equipment, called network cache, is introduced. The latter performs efficient flow caching and scheduling, in order to guarantee service continuity. The simulation shows that the proposed architecture gives satisfying service start-up delays and improves system scalability.
Download
Paper Nr: 50
Title:

CROSS-LAYER OPTIMIZATION FOR STREAMING MPEG4 VIDEO OVER HSDPA NETWORKS
Authors:

I. Abdeljaouad, TAJJEEDDINE RACHIDI and Hicham Bouzekri
Abstract: A novel cross layer optimization technique for efficient streaming of MPEG4 VIDEO over a High Speed Downlink Packet Access (HSDPA) network is proposed in this paper. The proposed technique uses the types of frames produced by the MPEG encoder to optimize the performance of the Hybrid Automatic Repeat reQuest (H-ARQ) protocol at the MAC layer. Our aim is to reduce the total power at the NodeB, and to increase the overall system throughput, while maintaining satisfactory user-perceived Quality of Service (QoS). The proposed technique consists in applying ARQ retransmission for MPEG4 I-frames (the most critical frame of an MPEG4 stream) upon the reception of a negative acknowledgment (NACK) message from the receiver (UE). Packet combining is then performed with the aid of the available I-frames at the receiver side. Different packet combining strategies have been investigated to assess the performance of the proposed cross-layer technique. We show that compared to the blind HARQ Chase Combining scheme applied indiscriminately to all MPEG4 frames, our scheme allows for saving up to 11% of the power at the NodeB, and up to 10% of the system bandwidth, while ensuring satisfactory video quality to users.
Download
Paper Nr: 53
Title:

HANDOVER PERFORMANCE ANALYSIS IN MOBILE IPv6 - A Contribution to Fast Detection Movement
Authors:

Javier Carmona-Murillo, José-Luis González-Sánchez and Isaac Guerrero-Robledo
Abstract: Nowadays, mobile communications face new challenges in its evolution: The convergence of wireless cellular networking and TCP/IP architecture. In addition, Internet protocols do not support mobility, so different mechanisms to offer seamless mobility have been proposed. The fourth generation (4G) IP-based wireless networks have lead IP level the ideal candidate where mobility should be implemented. Mobile IP is the protocol proposed for mobility management at the IP layer. Handover management is one of the most critical phases of this protocol. The high delay of this phase is a limitation to seamless mobility. In this work a detailed analysis about handover process is presented. Moreover, movement detection is a very costly stage in handover mechanism so a new fast movement detection algorithm to improve this detection has been developed. It is called FDML3 (Fast Detection Movement Layer 3). As the handover analysis as the algorithm proposed has been carried out thanks to OMNeT++ simulator.
Download
Paper Nr: 66
Title:

ON SUPPORTING REAL-TIME COMMUNICATION OVER THE IEEE 802.15.4 PROTOCOL
Authors:

Hoai Hoang and Jerker Bengtsson
Abstract: IEEE 802.15.4 is a new enabling technology for low data rate wireless personal networks. This standard was not specifically designed for wireless sensor networks, but it has shown to be a good match with necessary requirements on low data rate, low power consumption and low cost. Unlike the former 802.11 standard, the MAC protocol specified in IEEE 802.15.4 can operate in two different modes: beacon-enabled mode or non-beacon enable mode. In beacon-enabled mode, nodes can exclusively allocate a number of guaranteed time slots, similar to a resource reservation scheme. Hence, the IEEE 802.15.4 MAC protocol have sufficient capabilities for supporting real-time communication. This paper presents the key features of IEEE 802.15.4 which makes it an attractive standard to use for real-time wireless sensor networks. Two real-time protocols extending the IEEE 802.15.4 standard are reviewed. The purpose of this paper is to present the state of the art on real-time support over IEEE 802.15.4 for wireless sensor networks and to discuss the possibilities on improvements on both the standard and the real-time protocols extending the standard.
Download
Paper Nr: 80
Title:

DELAY EFFICIENT MAC PROTOCOL FOR DIFFUSION BASED ROUTING IN WIRELESS SENSOR NETWORKS
Authors:

Amir Yahyavi, Hamid Khalili and Naser Yazdani
Abstract: In this paper we present DESMAC a contention based Medium Access Control protocol for Diffusion based routing in Wireless Sensor Networks. One of the main challenges in WSNs is to balance delay efficiency and energy consumption. Surveillance and monitoring application as well as many other need low latency data delivery; but, since sensor nodes have a small source of energy usually Active/Sleep cycles are used to reduce the energy consumption which causes higher delay. We use routing information to adaptively change the duty cycle for different loads. In our Cross Layer Design the Routing Layer can manipulate the duty cycle of underlying MAC protocol. The diffusion control messages are used to adapt the duty cycle to variation in the load. Also extensive use of some nodes can damage the connectivity of network. Therefore we provide a mechanism to balance the load between several possible paths. We discuss DESMAC design and compare our simulation results to S-MAC and IEEE 802.11 standard. DESMAC achieves significant latency reduction (up to 50 times better delay than S-MAC) while ensuring energy efficiency and load balanced delivery.
Download
Paper Nr: 99
Title:

IDENTIFICATION OF DISTRIBUTED PARAMETER SYSTEMS BASED ON MULTIVARIABLE ESTIMATION AND WIRELESS SENSOR NETWORKS
Authors:

Constantin Volosencu
Abstract: One of the important problem related to the usage of wireless sensor networks in harsh environments is the identification of the states of the physical variables in the field, based on the measurements provided by the sensors. The sensor networks allow the usage of the multivariable estimation techniques in distributed parameter systems. The paper presents an application of a multivariable auto-regression estimation technique for identification in distributed parameter systems, based on a sensor network. A case study was presented for identification in a heat diffusion process.
Download
Paper Nr: 121
Title:

SURVEYING WI-FI SECURITY - Presentation of Wi-Fi Security Measures, Varius Wi-Fi Attacks and a Classification Survey of Wi-Fi Networks in Thessaloniki
Authors:

George E. Violettas, Tryfon L. Theodoroy, Konstantinos Chalkias and George Stephanides
Abstract: This paper is a study of the use and possible flaws of the two basic cryptographic protocols (WEP, WPA) in Wi-Fi Networks. It presents some very easy to implement methods to gain malicious access to such networks by disclosing the network secret key, using Windows Operating Systems, like Win XP. It also describes the shutter of the myth saying that the MAC Address filtering is a safe practice for securing a wireless network. There is a field research, in which we show the distribution of wireless networks according to the security protocol implemented (if any) at a major city centre in Greece. Unfortunately, according to our results, only 8% of the wireless networks are using a fairly safe cryptographic scheme, 48% is not using any security at all, while the rest is using the totally unsecure WEP encryption.
Download

Area 2 - Wireless Networking Technologies

Full Papers
Paper Nr: 30
Title:

IMPROVEMENT OF WIRELESS NETWORK ISOLATION AND SECURITY BY SHRUB BARRIERS
Authors:

Iñigo Cuiñas, Paula Gómez, Manuel García Sánchez and Ana Vázquez Alejos
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 bushes as a hurdle 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 by several specimens of seven different vegetal species. 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.
Download
Paper Nr: 74
Title:

FRAME LENGTH DESIGN FOR MULTIBAND-OFDM ULTRA WIDEBAND NETWORKS
Authors:

Liaoyuan Zeng, Eduardo Cano, Michael Barry and Sean Mc Grath
Abstract: A new design of the optimal MAC frame payload length for maximizing the saturation throughput of the Prioritized Contention Access (PCA) of the WiMedia Ultra Wideband (UWB) standard in Rayleigh fading channel is presented in this paper. In the WiMedia standard, the Multiband Orthogonal Frequency Division Multiplexing (MB-OFDM) is used as the basic physical scheme. The proposed design is based on the throughput analysis carried out by extending an original Enhanced Distributed Contention Access (EDCA) model for 802.11e into the MB-OFDM UWB protocol. The extended model considers the effects of the bit error rate, the transmission opportunity limits, and the uniqueness of WiMedia MAC timing structure. The station throughput is sensitive to the frame payload length, and the optimal frame payload length increases exponentially when the value of the signal-to-noise ratio is higher. The optimal payload length is independent of the number of the active stations, data rate, and the priority of the Access Categories (ACs). Therefore, a station can dynamically adapt the length of the transmitted frame in the MAC layer according to the current SNR level so as to maximize its saturation throughput in the MB-OFDM UWB network.
Download
Paper Nr: 74
Title:

FRAME LENGTH DESIGN FOR MULTIBAND-OFDM ULTRA WIDEBAND NETWORKS
Authors:

Liaoyuan Zeng, Eduardo Cano, Michael Barry and Sean Mc Grath
Abstract: A new design of the optimal MAC frame payload length for maximizing the saturation throughput of the Prioritized Contention Access (PCA) of the WiMedia Ultra Wideband (UWB) standard in Rayleigh fading channel is presented in this paper. In the WiMedia standard, the Multiband Orthogonal Frequency Division Multiplexing (MB-OFDM) is used as the basic physical scheme. The proposed design is based on the throughput analysis carried out by extending an original Enhanced Distributed Contention Access (EDCA) model for 802.11e into the MB-OFDM UWB protocol. The extended model considers the effects of the bit error rate, the transmission opportunity limits, and the uniqueness of WiMedia MAC timing structure. The station throughput is sensitive to the frame payload length, and the optimal frame payload length increases exponentially when the value of the signal-to-noise ratio is higher. The optimal payload length is independent of the number of the active stations, data rate, and the priority of the Access Categories (ACs). Therefore, a station can dynamically adapt the length of the transmitted frame in the MAC layer according to the current SNR level so as to maximize its saturation throughput in the MB-OFDM UWB network.
Download
Paper Nr: 92
Title:

MACRO DIVERSITY COMBINING SCHEMES FOR MULTICAST TRANSMISSION IN HIGH-SPEED CELLULAR NETWORKS
Authors:

neila el heni and Xavier Lagrange
Abstract: In this paper, we study the transmission of data destined for several users on the radio interface using the multicast mode, an interesting alternative of the conventional unicast mode. In the multicast mode, a packet is sent simultaneously to several terminals in the same cell. We consider different techniques of macro diversity, namely Selective Combining (SC) and Maximal Ratio Combining (MRC). We develop an analytical model that allows the computation of the mean bitrate for both multicast and unicast schemes. We use a scheduler that allocates bandwidth to mobiles according to their instantaneous channel quality. In this context, we propose an efficient user clustering considering their average radio channel quality. The study shows that macro diversity improves the transmission performance especially for pure multicast.
Download
Short Papers
Paper Nr: 21
Title:

PROPAGATION PHENOMENA FOR INDOOR WIMAX NETWORKS - Implications on Network Isolation and Security
Authors:

Iñigo Cuiñas and Manuel García Sánchez
Abstract: The impressive success of wireless networks must be supported by research in the radio level, to assure the performance of several networks sharing the same spectrum allocation and the same spatial position. This work provides the data measured along several years of experimental research in the 5 GHz band, including electromagnetic characterisation of different building materials, deterministic indoor radio channels analysis, as well as non deterministic effects as those introduced by people moving or by furniture within a static environment. Such information could be helpful for network designers to predict the network characteristics and to prevent against possible external non authorised access or isolation problems.
Download
Paper Nr: 23
Title:

VIRTUAL FREQUENCY REUSE TO INCREASE CAPACITY OF OFDM SYSTEMS
Authors:

Seung-Moo Cho and Tae-Jin Lee
Abstract: This paper presents a novel frequency reuse scheme that reduces the effects of co-channel interference and in-creases the capacity of orthogonal frequency division multiplexing (OFDM) systems. To increase the capacity of a system, the frequency reuse factor should be close to 1. In general, reduction of co-channel interference (CCI) is achieved at the cost of cell capacity. Our virtual frequency reuse (VFR) targets to mitigate such tradeoff. In VFR, the type of a cell is determined by the order of sub-channel assignment. And users in a cell are assigned sub-carriers among sub-channels by a specific regulation. Probabilistic interference analysis and simulation results show that the proposed virtual frequency reuse improves the performance of an OFDM system for both uniform and non-uniform distributions of traffic load.
Download
Paper Nr: 57
Title:

A NOVEL FRONT-END NOISE POWER AND SNR ESTIMATION USING WAVELET-PACKETS IN OFDM SYSTEMS
Authors:

Rana Shahid Manzoor, Varun Jeoti, Nidal Kamel and Muhammad Asif
Abstract: In this paper, a noise power estimator based on one OFDM preamble is proposed. The estimator, unlike others, performs noise power estimation at the front-end of the receiver. The proposed estimator takes into consideration the different noise power levels over the OFDM sub-carriers. The OFDM band is divided into several sub-bands using wavelet packet and noise in each sub-band is considered white. The second-order statistics of the transmitted OFDM preamble are calculated in each sub-band and the noise power is estimated. The proposed estimator is compared with Reddy’s estimator for colored noise in terms of mean squared error (MSE).
Download
Paper Nr: 59
Title:

PEAK-TO-AVERAGE POWER RATIO OF MULTITONE-HOPPING CDMA SIGNALS USING FEEDBACK-CONTROLLED HOPPING PATTERNS
Authors:

Kazuki Chiba and Masanori HAMAMURA
Abstract: We present the characteristics of peak-to-average power ratio (PAR) for multitone-hopping code-division multiple access (MH-CDMA) signals using feedback-controlled hopping patterns (FCHPs) (FCHP/MH-CDMA). In FCHP/MH-CDMA, since each chip of transmitted signals consists of plural tones, energy consumption due to large PAR may not be negligible at the transmitter. Therefore, it is important to investigate the PAR characteristics of FCHP/MH-CDMA signals. It is shown that limiting the number of tones per chip, and the number of quantization bits, and clipping on FCHP are effective in reducing the PAR at almost identical bit-error rate (BER).
Download
Paper Nr: 70
Title:

APPLYING NEURO-FUZZY DYNAMIC BUFFER TUNING TO MAKE WEB-BASED TELEMEDICINE SUCCESSFUL
Authors:

Jackei H. K. Wong, Chen Ye Zhu, Wan Kei Wilfred Lin and Kang Ying Allan Wong
Abstract: We propose to make web-based medical consultation successful by applying the Neuro-fuzzy Dynamic Logic Controller (NFLC). This is achieved for the NFLC shortens the service response time for the physician, who answers the patient requests pervasively, by dynamic buffer tuning. The physician carries a SFF (small form factor) mobile device (e.g. PDA) that provides the interface for interacting wirelessly with rest of the web-based telemedicine system (WTS) on the mobile Internet. The WTS in this paper caters to Traditional Chinese Medicine (TCM) and therefore called TCM-WTS or simply T-WTS. The T-WTS usability relies on various factors such as correct information exchange, and fast system response. This paper focuses on the second factor by exploiting real-time dynamic buffer tuning as a solution.
Download
Paper Nr: 73
Title:

A FIELD-VALIDATED LOCATION CONSCIOUS QOS PREDITION TOOL FOR WLL NETWORKS
Authors:

Hicham Bouzekri, Tajjeeddine Rachidi, Yassine Moussaif and Tarik Janati

Abstract: Wireless Local Loop (WLL) has become a viable alternative for the last mile problem, especially for emerging countries. However the success of a large scale deployment of such a technology relies on careful network planning taking into account existing building layout to achieve predictable quality of service (QoS) for each customer. This paper proposes an approach where actual geographical layout of the area to be covered is taken into account to distinguish line-of-sight (LOS), Obstructed Line-of-sight (OLOS) and non-LOS (NLOS) regions and uses adequate propagation models for each case. By doing so a more accurate prediction on achievable QoS is possible for each point of the area. The output of the tool is a point-by-point quantitative measure of received average signal strength prediction and an optimized overall coverage quality. Finally, field measurements and benchmarking were used to validate the approach adopted.
Download
Paper Nr: 95
Title:

MIMO-OFDM CHANNEL ESTIMATION - A Pilot Sequence Design for Time-domain Processing
Authors:

Carlos Ribeiro and Atilio Gameiro
Abstract: A pilot sequence design for MIMO-OFDM systems is investigated where all transmit antennas share the same sub-carriers to convey pilot symbols. The pilot sequences are endowed with phase-shifting properties, granting the receiver the possibility of extracting the impulse responses for all channels directly from the antennas’ time-domain received signals, without co-channel interference. A linear processing of the time-domain samples is all that is needed to get the channel impulse responses, resulting in an algorithm with very low computational load. The feasibility of the investigated method is substantiated by system simulation using indoor and outdoor broadband wireless channel models.
Download
Paper Nr: 25
Title:

ON THE PRACTICAL PERFORMANCE OF RATELESS CODES
Authors:

Miroslav Knežević, Vesselin Velichkov, Bart Preneel and Ingrid Verbauwhede
Abstract: We propose a new parameter for optimizing the performance of rateless codes by minimizing latency and data overhead. We call it Latency-Overhead Product (LOP). It is based on ideas used in the analysis of digital circuits. We demonstrate the effectiveness of the LOP parameter for a specific class of rateless codes called Online codes (OC). We give results from experiments in ideal channel and simulated wireless channel with losses. In the second part of our experiments we analyze the relationship between the message block size and the performance of rateless codes. With the results from these experiments we extend the results from the performance of Luby Transform (LT) codes published in (Vukobratovic and Despotovic, 2005) by adding figures for Online codes.
Download
Paper Nr: 85
Title:

PERFORMANCE ANALYSIS OF FSK MODULATION WITH LIMITER-DISCRIMINATOR-INTEGRATOR DETECTION OVER HOYT FADING CHANNELS
Authors:

Nazih Hajri and NEJI YOUSSEF
Abstract: The focus of this paper is on the performance analysis of frequency shift keying (FSK) modulation with limiter- discriminator-integrator (LDI) detection over frequency-flat Hoyt (Nakagami-q) fading channels. Specifically, a closed-form expression is derived for the probability density function (PDF) of the phase difference of Hoyt faded FSK signals disturbed by additive white Gaussian noise (AWGN). This newly derived PDF is verified to reduce to known results corresponding to the Rayleigh fading channel as a special case of the Hoyt model. The validity of the expression is further demonstrated by simulation for the case of a Hoyt mobile-to-mobile (M2M) fading channel. The analytical PDF of the phase difference is then applied to determine the bit-error probability (BEP) of the LDI receiver taking into consideration the Doppler effects, the click noise as well as the inter-symbol interference (ISI) caused by the intermediate frequency (IF) pre-detection filter. Numerical examples, assuming a Hoyt M2M channel, are given to illustrate the analysis and examine the effects of the FM system parameters and the fading characteristics on the BEP performance.
Download
Paper Nr: 102
Title:

MARKOV CHAIN BASED MODELS COMPARISON IN IEEE 802.16E SCENARIO
Authors:

Floriano De Rango, Andrea Malfitano, Angela Procopio and Salvatore Marano
Abstract: The IEEE 802.16e is a promising technology that allows to provide wireless broadband services to a great number of mobile users. Considering this interesting scenario enriched by further presence of HAPs (High Altitude Platform) with the role of Base Stations (BSs), we have proposed a comparison between performances of a set of Markov Chain based models collected by literature. These following models: MTA (Markov-based Trace Analysis), Gilbert – Elliot, FSM (Full-State Markov) and HMM (Hidden Markov Model) are designed using packet error traces (a sequence of “1” and “0”) obtained by a simulator that takes into account channel impairment effects such as path loss and Doppler effect. To compare the models performances, by each of them artificial traces are generated and then Entropy Normalized Kullback-Leibler distance, standard error and other statistical properties of random variable G (free error packets burst length) and B (corrupted packets burst length) of artificial traces are computed. The purpose of this work is to identify the model that best describes the channel error behaviour in IEEE 802.16e.
Download
Paper Nr: 104
Title:

CARRIER AND SYMBOL PHASE SYNCHRONIZERS
Authors:

Antonio Reis, Jose Rocha, Atilio Gameiro and José A. R. Pacheco de Carvalho
Abstract: This paper presents two groups of synchronizers, namely the Carrier Phase Synchronizer and the Symbol Phase Synchronizer. In the first group the VCO (Voltage Controlled Oscillator) synchronizes with the input periodic signal and in the second the VCO synchronizes with a no periodic signal. Each group is studied under four topologies, namely the analog, hybrid, combinational and sequential. The objective is to evaluate the two groups with their four topologies and to observe the jitter-noise behaviours.
Download

Area 3 - Mobile Software and Services

Full Papers
Paper Nr: 9
Title:

RELATIVE NODES LOCALIZATION IN WIRELESS NETWORKS USING RECEIVED STRENGTH SIGNAL VARIATIONS
Authors:

Mohamed Salah Bouassida and Mohamed Shawky
Abstract: The geographical localization of entities in a wireless network is one of the most important issues of neighborhood awareness. A precise localization provides an advantage for the geographically-located services. However, the geographical localization within a wireless network should take into account the characteristics and the specificities of such environment. In this paper, we present a technique allowing a receiver to localize a sender within its range, without additional devices, as a GPS (Global Positioning System). We use only 3 RSSIs (Received Strength Signal Indicators) measurements, under the assumption that the sender sends messages with the same signal strength.
Download
Paper Nr: 71
Title:

AN EXTENDED ANALYSIS OF AN INTEREST-BASED SERVICE DISTRIBUTION PROTOCOL FOR MOBILE AD HOC NETWORKS
Authors:

Mohamed Hamdy and Birgitta König-Ries
Abstract: In principle, service orientation is a suitable paradigm to allow for effective resource sharing in wireless ad hoc networks. However, special attention needs to be paid to ensure a high service availability since this is the basis for reliable service execution. Unfortunately, typical characteristics of ad hoc networks like ever-changing topology and limited resources have a dramatic negative effect on service availability. Therefore, special measures are needed to cope with this problem. In general, replication for services as well as data represents an efficient solution when the availability of some resource needs to be ensured. In this paper, we extend the service replication and distribution protocol presented in our prior work which is based on the interest of clients and providers of a specified service by taking into account not just one but all partitions of the network. By elaborating an extensive detailed simulation, the efficiency of replication and the allocation correctness are being examined. The results show that relying on our protocol is feasible. Since our protocol utilizes high level (application level) information about the available services in the ad hoc network only and does not rely on lower level information like network or protocol specifics, it is applicable in a wide range of settings.
Download
Short Papers
Paper Nr: 26
Title:

IMPROVED CHANNEL SWITCHING FOR HYBRID UNICAST/BROADCAST MOBILE TELEVISION
Authors:

Stefan Diepolder and Jan Kritzner
Abstract: Today’s 3G networks enable the delivery of mobile television services to the user. However, the distribution mechanism differs from conventional television broadcasting. For an effective mobile TV system both unicast and multicast transmission are combined. One weak point of digital television is channel switching. Both the underlying network and the data structure impose partially unavoidable delays. In this paper we present a mobile television architecture which supports fast stream switching and present different techniques to reduce at least the perceived switching duration. The different switching scenarios between unicast and multicast are discussed in detail. This paper presents work in progress, so both already implemented and future extensions are described. Though the implementation has been done with a 3G background the algorithms can be applied to every digital television scenario.
Download
Paper Nr: 33
Title:

A VEHICULAR HEALTHCARE SYSTEM USING ANYCAST AND PERVASIVE COMPUTING - One Pervasive Computing Application on Mobile Software and Services
Authors:

Max Meng-Yu Lee and Jiun-You Wang
Abstract: One vehicular healthcare system is proposed to provide secure and stable transmission in wireless environments. Using anycast and pervasive computing technology, the robustness and real-time transmission model is provided for the ambulance to communicate with the target hospital via wireless GPRS transmission in very limited and tolerant data loss. The message reliable transmission method between the ambulance and the hospital with 3 Transmission Devices connecting to 3 GPRS networks is proposed. Each time two out of three TDs are selected to transmit the packet and its duplicate. Using anycast, it doesn’t cause the overload condition as with multicast, one MRN selection method is proposed for the router to achieve the load-balancing condition in MRG.
Download
Paper Nr: 108
Title:

IMPROVING DIRECTORY-LESS WLAN POSITIONING BY DEVICE WHISPERING
Authors:

Karl-Heinz Krempels and Krebs Martin
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.
Download
Paper Nr: 68
Title:

GENERATING TRAFFIC INFORMATION THROUGH MOBILE MESSAGING
Authors:

Rajni Jindal and Ankur Gupta
Abstract: The paper proposes a new means of generating traffic information within a traffic information system by having mobile users message the traffic data to the system. This paper is a part of a work in progress to propose and implement an Open Traffic Information System (OTIS). All existing TISs either require significant investments in new infrastructure or depend on third party sources to generate traffic information whereas the proposed system could be instantaneously deployed over the existing cellular network.
Download
Paper Nr: 87
Title:

PERFORMANCE EVALUATION OF JSON AND XML FOR DATA EXCHANGE IN MOBILE SERVICES
Authors:

Ivar Jørstad, Elias Bakken and Tor Anders Johansen
Abstract: One of the major challenges of developing mobile services is that of data transfer back and forth between the mobile device and the server side application parts. This paper provides a performance analysis and comparison on the use of XML and JSON for data exchange for mobile services. Results obtained from common emulators are provided, as well as results from live operation on state-of-the-art mobile devices.
Download
Paper Nr: 113
Title:

JAVA-C++ BRIDGE FOR SYMBIAN BASED SMARTPHONES
Authors:

Balázs Goldschmidt, Gergo Gyano and Balázs Goldschmidt
Abstract: Authors propose a simple framework in order to help smartphone developers gain both from the advantages of J2ME and C++ in Symbian OS. The idea is that while JNI is not supported by J2ME, with the help of the built-in networking support a daemon written in C++ can serve as a function-provider in cases when problems with pure J2ME features can not be solved.
Download
Paper Nr: 114
Title:

AN OSGi BASED MOBILE DEVELOPMENT OVERVIEW
Authors:

Pascal Suetterlin, Olaf Thiele and Hartwig Knapp
Abstract: This paper presents an overview of the three most promising platforms for developing mobile applications: Titan (Java), Google Android and the iPhone. While the Titan platform already implements most design goals, Google’s Android platform is in an early development stage. The iPhone platform lacks most functionality, but will soon be enhanced by a new firmware. The main focus in our comparison lies on the deployment and management of applications through the Open Services Gateway Initiative (OSGi) framework.
Download
Paper Nr: 118
Title:

A LOCATION AND BANDWIDTH AWARE P2P VIDEO ON DEMAND SYSTEM FOR MOBILE DEVICES
Authors:

Danilo F. S. Santos and Angelo Perkusich
Abstract: Due the increasing number of new wireless technologies and the advent of new mobile devices, new services and applications are necessary to supply the needs of these devices users. Video on-Demand (VoD) services have become one of these services. In this paper we present a proposal of a P2P Mobile Video on-Demand (VoD) System focused on mobile devices where they can act as both, media servers as well as clients. Due to different possible communication interfaces that are available for mobile devices, we considered that they can be in networks with different throughput characteristics, and also, they can be distributed through the Internet. Therefore, our proposal make possible to build content distribution trees in the application layer considering two major aspects related to mobility: the available bandwidth that the mobile device can share with the network, and; the relative position of the mobile device in the network.
Download