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Wireless Pervasive Computing (ISWPC), 2010 5th IEEE International Symposium on

Date 5-7 May 2010

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Displaying Results 1 - 25 of 111
  • [Front cover]

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  • Author index

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  • Achievable diversity limits in a quantized MIMO-OFDM linear pre-coded system

    Page(s): 455 - 459
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (274 KB) |  | HTML iconHTML  

    In this paper, the effects of quantization on the achievable diversity of a linearly precoded Space-Time-Frequency (STF) and Space-Frequency (SF) coded MIMO-OFDM system are studied. A relationship between the maximum achievable diversity in a linearly precoded system and the number of quantization bits is derived. The performance of two different STF codes for various levels of quantization is simulated. These simulations are performed on an equal two ray channel, as well as a realistic channel. The simulations results matched the results predicted by the derived expressions. The effects of quantization on the diversity that STF and SF linearly precoded systems are able to extract, have been mathematically quantified. View full abstract»

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  • Open source simulation of smart antenna systems in network simulator-2 using Octave

    Page(s): 51 - 56
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (401 KB) |  | HTML iconHTML  

    This paper presents a simulation platform that exploits the scalability properties of network simulator-2 (ns-2) for the discrete-event simulation of a telecommunication network, and adopts the open source tool Octave for the discrete-time implementation of adaptive antenna arrays. The physical antenna system, the beamforming algorithm, and the multipath statistic are modeled in detail to accurately estimate the Signal to Interference Ratio (SIR) at each receiving node. This study describes the methods that can be used to interface Octave with ns-2 and compares the developed solution to an existing one, based on the proprietary tool MATLAB, discussing the advantages and disadvantages that characterize the two platforms. View full abstract»

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  • On ultra wideband channel modeling for in-body communications

    Page(s): 140 - 145
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (578 KB) |  | HTML iconHTML  

    Innovative medical applications such as implant wireless sensors for health monitoring, automatic drug deliverance, etc. can be realized with the use of ultra wideband (UWB) radio technology. Nevertheless, for efficient design of wireless systems operating inside the human body a radio communication channel model is essential. Although a lot of research effort has recently been devoted to the characterization of the on-body UWB radio communication channel, just a few works describing the radio propagation inside the human body have been reported. To address this problem, a computational study of the propagation of UWB signals through human tissues in the 0.1–1 GHz and 1–6 GHz frequency bands is presented in this paper. This is based on numerical simulations using a heterogeneous anatomical model of the human body with frequency dependent tissue material properties. Subsequently, a statistical channel model is introduced for UWB in-body communications in the 1–6 GHz frequency band. The model is provided for two typical depths inside the human chest. This work contributes to the practical design of UWB medical implant communication systems. View full abstract»

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  • Control information exchange through UWB in cognitive radio networks

    Page(s): 110 - 115
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB) |  | HTML iconHTML  

    The implementation of a common control channel is one of the most challenging issues in cognitive radio networks, since a fully reliable control channel cannot be created without reserving bandwidth specifically for this purpose. In this paper, we investigate a promising solution that exploits the Ultra Wide Band (UWB) technology to let cognitive radio nodes discover each other and exchange control information for establishing a communication link. The contribution of this paper is threefold: (i) we define the communication protocol needed to let cognitive radio nodes discover each other and exchange control information for link set up, (ii) we overcome the gap in coverage, which typically exists between UWB and long-medium range technologies, by using multihop communications, (iii) we evaluate the performance of our approach and show its feasibility through extensive simulations. View full abstract»

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  • Performance analysis of energy efficient asymmetric coding and modulation schemes for Wireless Sensor Networks

    Page(s): 460 - 464
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (805 KB) |  | HTML iconHTML  

    Wireless Sensor Networks generally operate under severe energy constraints. In many cases, the networks are star connected with battery-powered nodes sensing data and sending it to a centrally-powered base station, whose energy constraints are more fore-bearing than that of the nodes. In this paper, an approach for energy efficient communication by using different channel codes on the base-station to node link (downlink) and node to base-station link (uplink) is proposed and analysed for such a network topology. This is in effect shifting complexity from the node to the base station while continuing to have the same BER performance. Also the use of more energy efficient modulation schemes are explored. View full abstract»

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  • Benchmarking of VoIP over HSDPA and LTE performance with realistic network data

    Page(s): 401 - 406
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (459 KB) |  | HTML iconHTML  

    The purpose of this paper is benchmark the performance of voice over IP in high speed downlink packet access and in long term evolution networks. Benchmarking is conducted in homogeneous and heterogeneous scenario layouts assuming realistic propagation data generated over Tokyo map. Tools used in this paper are two fully dynamic time driven system simulators which have been used to support 3GPP standardization work. This benchmarking study provides insights to what e.g. different radio access technologies, scheduling mechanisms and receivers do for the performance of voice over IP. This paper indicated in various scenarios that long term evolution can offer higher performance for voice over IP than high speed packet access. View full abstract»

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  • Spectrum management techniques with QoS provisioning in cognitive radio networks

    Page(s): 116 - 121
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (300 KB) |  | HTML iconHTML  

    In this paper, we discuss the spectrum management technologies including spectrum sensing, spectrum decision, spectrum sharing, and spectrum handoff schemes in cognitive radio (CR) networks. In order to evaluate performance of different spectrum management schemes, the preemptive resume priority (PRP) M/G/1 queuing model is suggested to characterize the spectrum usage behavior between the primary and the secondary users. Based on this model, we derive a new performance measure — the overall system time of the secondary connections. The overall system time is an important performance measure to provide the quality of service (QoS) provisioning service for the secondary users. It is defined as the duration from the instant that data arrives at system until the instant of finishing the whole transmission. Clearly, multiple interruptions from the high-priority primary users will increase the overall system time of the low-priority secondary users. Based on the PRP M/G/1 queuing model, the impacts of multiple interruptions on the overall system time can be evaluated. On top of this model, a spectrum sensing, a spectrum decision, a spectrum sharing, and a spectrum handoff algorithms are investigated to reduce the overall system time. From the numerical results, we can design better spectrum management policies to satisfy the QoS requirement of the secondary users in CR networks and provide useful insight into the design tradeoff for different spectrum management technologies.1 View full abstract»

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  • Wireless optical OFDM implementation for aircraft cabin communication links

    Page(s): 465 - 470
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1869 KB) |  | HTML iconHTML  

    The state of development of optical devices has led to increased interest in high data rate wireless optical communication schemes that today constitute a viable alternative to conventional wireless technologies for information exchange. In this work, a high data rate wireless optical link, based on OFDM modulation, conventional laser diodes and large area photodiodes, was implemented and investigated. A laboratory prototype was used to demonstrate a data rate of 19.6Mbit/s. A 64-subcarrier OFDM signal with different subcarrier modulation schemes (BPSK, QPSK) was examined. Target applications are video, high speed internet etc. within the confines of an intra-cabin wireless optical topology View full abstract»

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  • Full-rate distributed space-time coding for bi-directional cooperative communications

    Page(s): 22 - 26
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (321 KB) |  | HTML iconHTML  

    In this paper, a protocol for bi-directional cooperative communications applying full-rate distributed space-time codes and physical network coding is proposed. This scheme uses L relays to transmit the codewords in a distributed fashion. It takes 3 time slots for two sources to transmit two corresponding codewords by exploiting physical network coding and self-interference cancelation at each source. We prove that this scheme obtains full diversity. The analytical results show that the diversity order of this scheme will be L + 1, where L is the number of relays. In addition, we assess the sum-rate of the bi-directional cooperative communication scheme and reveal that it achieves larger spectral efficiency compared to one-way cooperative communication scheme. We employ Monte Carlo simulations to validate the symbol error rate and the ergodic sum-rate of the scheme. View full abstract»

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  • Average waiting time of packets with different priorities in cognitive radio networks

    Page(s): 122 - 127
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (284 KB) |  | HTML iconHTML  

    In this paper, we investigate the average waiting time of packets with different priorities in cognitive radio networks (CRN) using a preemptive priority queuing system. Specifically, we consider two scenarios for CRN, the first with the secondary user (SU) sensing at the beginning of each time slot and the other with the SU having continues sensing ability. Our analysis shows that the average waiting time of packets for the SU does not only depend on the size of packets and arrival rate of the SU traffic but also depends on the arrival rate and size of packets from primary users (PU). Moreover, the results show that an SU with continuous sensing ability can utilize spectrum better than sensing at the beginning of each time slot. View full abstract»

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  • Low-cost wireless link capacity estimation

    Page(s): 343 - 348
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (985 KB) |  | HTML iconHTML  

    Wireless link quality estimations are essential for the optimal operation of various network functions like routing and rate adaptation. In this paper, we present a new link quality metric named Effective Link Capacity (ELC), which predicts link capacity by utilizing information such as the packet delivery ratio (PDR) and the transmission count of data packets (TXC). ELC requires no active probing and hence incurs zero overhead, while using only locally-available information from the transmitting node. Using our conducted testbed, we evaluate the accuracy of ELC on both single link and hidden terminal scenarios, with different configurations of packet sizes, link rates and offered loads. We also corroborate our conducted testbed findings with an evaluation of ELC for varying amounts of offered load on a live wireless data link in an office environment and find that ELC is highly accurate, with a maximum Root Mean Squared Error (RMSE) of 4.43%. We also compare ELC against a known bandwidth estimation tool, PathChirp, and find that ELC's RMSE of 0.68% far outperforms Path Chirp's RMSE of 18.66%. View full abstract»

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  • Wireless networks at the service of effective first response work: The E-SPONDER vision

    Page(s): 210 - 214
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (551 KB) |  | HTML iconHTML  

    This paper presents the work that is currently performed in the E-SPONDER (FP7–242411) project. E-SPONDER is a suite of real-time data-centric technologies which will provide actionable information and communication support to first responders that act during normal and abnormal events (crises). This information will enable improved control and management, resulting in real time synchronization between forces on the ground (police, rescue, firefighters) and out-of-theater command and control centers (C&C). The approach guiding the E-SPONDER project is based on the fusion of variable forms of field-derived data within a central system which will then provide information analysis and decision support applications at designated C & C locations in order to provide in situ support to first responders that operate in Critical Infrastructures. View full abstract»

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  • Eavesdropping wireless video packets to improve standard multicast transmission in Wi-Fi networks

    Page(s): 471 - 476
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (509 KB) |  | HTML iconHTML  

    This paper proposes WEVCast, (Wireless Eavesdropping Video Casting) a new mechanism to overcome the performance obtained by wireless multicast transmission of video contents over standard Wi-Fi networks. We described this new strategy pointing out few specific features of our proposal such as the simplicity, the robustness and the extreme compatibility with all off-the-shelf wireless devices; in addition, we validated our idea throughout a quite realistic simulation framework well designed for perceived video quality evaluation. The obtained results confirm the goodness of the proposed solution making it very attractive for the new multimedia video content delivery services. View full abstract»

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  • Performance of idle mode mobility state detection schemes in Evolved UTRAN

    Page(s): 584 - 588
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB) |  | HTML iconHTML  

    In this paper we study the performance of idle mode mobility state detection schemes targeted for 3rd Generation Partnership Project (3GPP) Evolved UTRAN. The purpose is to compare the mobility state detection scheme specified in 3GPP Release 8 and a dual trigger scheme for 3GPP Release 9 using different User Equipment (UE) velocity conditions and cell reselection triggering sensitivity levels. A single set of cell reselection parameters may not be optimal throughout the E-UTRAN velocity range, thus both schemes provide in a way a means of using UE velocity dependent cell reselection parameters. According to the results, both schemes provide gain over a single set of cell reselection parameters. Dual trigger provides gain over Release 8 mobility state detection scheme in terms of time spent in the best cell and downlink SINR. However, this comes with a small increase in power consumption due to increased amount of cell reselections per UE. View full abstract»

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  • Non-cooperative block-faded orthogonal multiple access with source correlation: Performance limits and practical schemes

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (286 KB) |  | HTML iconHTML  

    In this paper, we study the performance of non-cooperative wireless multiple access systems with noisy separated channels, where correlated sources communicate to an access point (AP) in the presence of block-faded links. This is meaningful for pervasive wireless scenarios, e.g., wireless sensor networks, where information may be exchanged between a multitude of nodes. Our goal is to explore the potential benefits which can be obtained when source correlation is exploited at the AP, comparing the performance with that obtained by using distributed source coding (DSC) at the nodes. We consider both the average bit error probability and the outage probability as performance indicators, and we derive a theoretical approach to evaluate their limits. Our results show that the improvement brought by the exploitation of the correlation at the AP is more evident when the correlation becomes sufficiently high. Moreover, some simulation results are presented for two classes of channels codes: serially concatenated convolutional codes (SCCCs) and low-density parity-check (LDPC) codes. Our results show that SCCCs can exploit better the correlation in scenarios with high values of the correlation coefficient (e.g., 0.999). View full abstract»

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  • In-sensor low-complexity audio pattern recognition for pervasive networking

    Page(s): 215 - 220
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (313 KB) |  | HTML iconHTML  

    In the last years, wireless sensor networking has become a key technology for making pervasive communications a reality. To this end, wireless sensor nodes need to consume as less energy as possible and, thus, the complexity of any onboard signal processing operation needs to be kept as low as possible. In this paper, we present a low-complexity detection approach for the recognition of different audio signal patterns, expedient, for example, for intrusion control in critical areas. To this end, the proposed detection algorithm evolves through two main processing phases: (a) coarse and (b) fine. The evolution between these two phases is described through a finite state machine (FSM) model. In fact, fine processing (in the frequency domain) is carried out only when an “atypical” audio signal is detected. On the other hand, coarse processing (in the time domain), performed a larger number of times, has a much lower complexity. Our results show that our processing technique allows to detect efficiently the presence of signals of interest (identified by properly selected spectral signatures) and to reliably distinguish different audio signal patterns, e.g., between speech and non-speech signals. While we first present simulation-based performance results of the proposed detection algorithm, we then validate our approach with realistic experimental results based on audio signals acquired with a commercial microphone. View full abstract»

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  • Non-regular network performance comparison between HSDPA and LTE

    Page(s): 568 - 572
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1128 KB) |  | HTML iconHTML  

    In this paper we study and benchmark the performance of 3rd Generation Partnership Project (3GPP) High Speed Downlink Packet Access (HSDPA) and 3GPP Long Term Evolution (LTE) Downlink with constant bit rate type traffic. In addition a non-regular simulation scenario is considered using realistic propagation data and base station positions related to Tokyo city downtown area. HSDPA was introduced in 3GPP Release 5 and in further releases the technology has been improved with e.g. receive and transmit diversity technologies and support for higher order modulation schemes. LTE was introduced in 3GPP Release 8 with completely new physical layer and improved Radio Resource Management (RRM) functionalities. The benchmarking is performed with fully dynamic system level simulators based on detailed and commonly accepted models for e.g. mobility, propagation, call generation and fading. The results show that LTE Release 8 outperforms HSDPA Release 8 in terms of spectral efficiency and user throughput. With 8 UEs per cell and LTE MIMO about 90% of UEs are fully satisfied, while about 45% of the UEs are fully satisfied with HSDPA MIMO. This results also about 30% gain in spectral efficiency even through with LTE the network is running half empty due to uneven UE distribution in non-regular network with variable cell sizes. View full abstract»

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  • Enhancing HSUPA system level performance with dual carrier capability

    Page(s): 579 - 583
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (325 KB) |  | HTML iconHTML  

    The purpose of this paper is to analyze how dual carrier capability can enhance High Speed Uplink Packet Access performance in comparison to using only single carrier. Dual carrier operation gives the User Equipment the possibility to transmit simultaneously using two 5 MHz bands, theoretically doubling the peak data rates and user throughput. The analysis is conducted with a system level simulation tool. This paper first indicates with single carrier simulations that, especially in small cells, terminals have spare power available for dual carrier operation. These observations are verified with dual carrier simulations by showing that the burst throughput can be practically doubled. In the larger cells only the users in good position can fully benefit from using dual carrier. View full abstract»

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  • Performance of Dynamic Service Addition in mobile WiMAX networks

    Page(s): 612 - 617
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    In WiMAX mobile networks (IEEE 802.16e–802.16m), connections, also referred to as service flows, can be dynamically activated between the base station and the mobile stations, by using a three-way handshake protocol referred to as Dynamic Service Addition (DSA). However, degraded channel quality and unreliable message retransmissions may lead to a delayed or even unsuccessful activation of a service flow. In this paper, a thorough analysis of DSA protocol performance is carried out under a variety of scenarios. Blocking probability, admission control probability, and latency of DSA protocol are evaluated, by means of simulations, for different conditions of mobility and parameters of PHY and MAC layers. Results show the negative impact of a long channel coherence time caused by low mobility and of the loss of channel reciprocity. Results offer indications on how to compensate such effects. View full abstract»

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  • Speaker Count application for smartphone platforms

    Page(s): 361 - 366
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (511 KB) |  | HTML iconHTML  

    This paper presents a Speaker Count (SC) algorithm based on pitch estimation designed to recognize singlespeaker audio recordings from two-speaker recordings. The paper reports the implementation for Symbian OS smartphones. The proposed solution is aimed at limiting implementation complexity and related battery consumption with respect to the schemes available in the literature. This action is mandatory due to the restricted resources available on smartphones. A practical experimental campaign of the proposal is conducted in real smartphones. The Speaker Count method has produced encouraging experimental results. The results also show that the implemented method allows saving energy and acting in a reasonable amount of time. View full abstract»

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