Showing papers in "Wireless Personal Communications in 2009"
TL;DR: The paper presents two approaches to cope with the problem of security and putting the user back in control despite the move to the Internet of things: The Identinet and a concept designated by the digital shadow.
Abstract: There are two problem areas of the current Internet to be solved in Future Internet scenarios--security and putting the user back in control despite the move to the Internet of things. With this in mind, we address problems associated with the diversifying of the Internet towards an Internet of things, and with increased ways to be reachable, whether the user wants it or not, in the digital world. The paper presents two approaches to cope with the problem: The Identinet and a concept designated by the digital shadow. The paper presents an architecture based on these concepts.
222 citations
TL;DR: The high level architecture of an intelligent city ecosystem, key enabling technologies, and the necessary policy framework for the establishment of digital cities worldwide are introduced.
Abstract: The digital revolution that has been taking place for the past two decades propelled by major breakthroughs in the ICT field has changed the way we communicate, work, travel, live--and even the way we use public space. Our cities are increasingly moving from a collection of static buildings and infrastructures to dynamic and evolving smart ecosystems known as, Intelligent Cities. In this article we analyze an intelligent city from the electronic information and communication perspective and offer examples of variants of its implementation. An intelligent city lays its foundation on a digital-city infrastructure which connects a local community and drives growth, efficiency, productivity, and competitiveness. The high level architecture of an intelligent city ecosystem, key enabling technologies, and the necessary policy framework for the establishment of digital cities worldwide are introduced. Business models for this new ecosystem bridging the physical and virtual worlds are briefly discussed.
189 citations
TL;DR: In this paper, the role of the mobile device is changed from being an agnostic entity in respect to the surrounding world to a cognitive device, which is capable of being aware of the neighboring devices as well as on the possibility to establish cooperation with them.
Abstract: This article advocates a novel communication architecture and associated collaborative framework for future wireless communication systems. In contrast to the dominating cellular architecture and the upcoming peer-to-peer architecture, the new approach envisions a cellular controlled short-range communication network among cooperating mobile and wireless devices. The role of the mobile device will change, from being an agnostic entity in respect to the surrounding world to a cognitive device. This cognitive device is capable of being aware of the neighboring devices as well as on the possibility to establish cooperation with them. The novel architecture together with several possible cooperative strategies will bring clear benefits for the network and service providers, mobile device manufacturers and also end users.
129 citations
TL;DR: Results on pathloss, power-delay profiles (PDPs), and delay-Doppler spectra from a high speed measurement campaign on a highway in Lund, Sweden are presented.
Abstract: The development of efficient vehicle-to-vehicle (V2V) communications systems requires an understanding of the underlying propagation channels. In this paper, we present results on pathloss, power-delay profiles (PDPs), and delay-Doppler spectra from a high speed measurement campaign on a highway in Lund, Sweden. Measurements were performed at a carrier frequency of 5.2 GHz with the communicating vehicles traveling on the highway in opposite directions. A pathloss coefficient of 1.8 shows the best fit in the mean square sense with our measurement. The average root mean square (RMS) delay spread is between 263 ns and 376 ns, depending on the noise threshold. We investigate and describe selected paths in the delay-Doppler domain, where we observe Doppler shifts of more than 1,000 Hz.
113 citations
TL;DR: A colored multigraph based model for the temporarily available spectrum bands, called spectrum holes, is proposed and a polynomial time algorithm is proposed to develop a routing and interface assignment, where n is the number of nodes in a CR network.
Abstract: In this paper, the cross-layer design routing in cognitive radio(CR) networks is studied. We propose a colored multigraph based model for the temporarily available spectrum bands, called spectrum holes in this paper. Based on this colored multigraph model, a polynomial time algorithm with complexity O(n 2) is also proposed to develop a routing and interface assignment, where n is the number of nodes in a CR network. Our algorithm optimizes the hop number of routing, meanwhile, the adjacent hop interference (AHI) is also optimized locally.
63 citations
TL;DR: The trust model, which is based on the ant colony system, is able to select the best server to interact with, in terms of being the most trustworthy, in a very high percentage.
Abstract: Many researchers are working hard in order to improve the capabilities of P2P networks. In this way, one of the main factors slowing down the improvement and development of P2P networks is the need to guarantee a minimum level of trust between two interacting nodes. This paper presents an innovative trust model providing a solution to this problem. Our trust model, which is based on the ant colony system, is able to select the best server to interact with, in terms of being the most trustworthy, in a very high percentage. Here, the traces of pheromone left by the ants correspond to the amount of trust that a node has on its neighbors.
52 citations
TL;DR: The obtained results show that the proposed location sensing system can achieve better positioning accuracy as compared to existing positioning system and in some cases accuracy improvement of about 50% can be reached.
Abstract: One of the biggest challenges in RFID (radio frequency identification) large scale deployment, such as in warehouse RFID deployment, is the positioning of RFID reader antennas to efficiently locate all the tagged objects distributed at RFID reader environment. This paper has investigated a novel location sensing system based on geometric grid covering algorithm that can use any passive or active RFID standard for positioning or tracking objects inside buildings. This study involves design of RFID reader antenna network which focuses on placing the reader antennas on a grid to cover all the tags distributed at two dimensional planes and position calculation using statistical averages algorithm. The statistical averages algorithm simply computes the location coordinates of the tagged object by statistical average of the reader antenna's location. The proposed grid of reader antennas can assist in minimizing the actual number of reader antennas required for RFID large scale deployment. The proposed prototype system is a simpler positioning system which presents the solution of placement pattern of RFID reader antennas, gives less complicated mathematical calculation, and is able to provide a high degree of accuracy. The obtained results show that the proposed location sensing system can achieve better positioning accuracy as compared to existing positioning system and in some cases accuracy improvement of about 50% can be reached.
50 citations
TL;DR: A simple 3-D geometric scattering model for the uplink of a macrocell mobile environment that provides the statistics of Angle-of-Arrival (AoA) of the multipath components and extends the 2-D geometrical-based single bounce macrocell (GBSBM) model.
Abstract: One of the fundamental research areas in wireless communications is the development of realistic models that can efficiently and accurately describe the wireless propagation channel. Most of the proposed models disregard the three dimensional character of the signal spread or use techniques with excessive computational complexity. In this paper, we develop a simple 3-D geometric scattering model for the uplink of a macrocell mobile environment that provides the statistics of Angle-of-Arrival (AoA) of the multipath components. The model extends the 2-D geometrical-based single bounce macrocell (GBSBM) model. Explicit closed-form expressions are derived for the statistics of the AoA of the multipaths in the azimuth and elevation planes. Analysis of the results exhibits the advantages of our proposal compared to 2-D and 3-D ones published in the literature. Comparisons with experimental data confirm its validity. Interesting conclusions for the effective evaluation of mobile communication systems have been derived. Moreover, an application of the model to mobile location estimation has been developed and evaluated.
45 citations
TL;DR: A utility-based approach is proposed for the evaluation of different access allocation choices, which is based on user and network policies, the performance of access bearers, and the availability of access resources.
Abstract: Communication networks and mobile devices integrate an increasing number of access technologies. At the same time, new business roles emerge, which lead to new cooperation schemes between access providers providing different types of access connectivity. As a result, a variety of access technologies will be available for users at the same time. In this article we present an architecture and a framework capable of integrating different access systems into a multi-access system and selecting the best suited access for users. A utility-based approach is proposed for the evaluation of different access allocation choices, which is based on user and network policies, the performance of access bearers, and the availability of access resources. We present a general multi-access management framework, which integrates the different multi-access related functions: access detection, access evaluation and access selection, which can then lead to an access handover.
44 citations
TL;DR: This paper proposes an effective location cloaking mechanism based on spatial networks and two novel query algorithms, PSNN and PSRQ, for answering nearest neighbor queries and range queries on spatial Networks without revealing private information of the query initiator.
Abstract: Due to the popularity of mobile devices (e.g., cell phones, PDAs, etc.), location-based services have become more and more prevalent in recent years. However, users have to reveal their location information to access location-based services with existing service infrastructures. It is possible that adversaries could collect the location information, which in turn invades user’s privacy. There are existing solutions for query processing on spatial networks and mobile user privacy protection in Euclidean space. However there is no solution for solving queries on spatial networks with privacy protection. Therefore, we aim to provide network distance spatial query solutions which can preserve user privacy by utilizing K-anonymity mechanisms. In this paper, we propose an effective location cloaking mechanism based on spatial networks and two novel query algorithms, PSNN and PSRQ, for answering nearest neighbor queries and range queries on spatial networks without revealing private information of the query initiator. We demonstrate the appeal of our technique using extensive simulation results.
42 citations
TL;DR: An overview of the state of the art in implementing cooperation approaches is provided, how appropriate these approaches solve the issues, and, where appropriate, their deficiencies are pointed out.
Abstract: In future wireless networks devices may cooperate to form logical links. Each of these links may consist of several independent physical channels which are shared by the cooperating partners. Even without multiple antennas this cooperation provides diversity in time and space. This so-called cooperation diversity increases the robustness of the link vs. fading and interference. After surveying approaches in cooperation diversity we focus on optimizing its performance by combining several cooperation schemes and by integrating cooperation into space-time coding. For multiple scenarios, we further discuss the factors and benefits introduced by user cooperation and how cooperation-aware resource allocation can be employed to further increase the performance of cooperative networks. When it comes to implementation, the question arises how cooperation can be integrated efficiently into existing wireless networks. A case study for 802.11-based WLANs reveals the issues that need to be solved in order to deploy cooperative techniques. We provide an overview of the state of the art in implementing cooperation approaches, analyze how appropriate these approaches solve the issues, and, where appropriate, point out their deficiencies. We conclude with a road map for future research necessary to tackle these deficiencies for the practical implementation of cooperation in next generation mesh, WLAN, WMAN, and cellular standards.
TL;DR: In this paper, the overheads associated with a NEMO fast handover include the latency, buffering cost, and packet loss cost, all of which are formulated based on a timing diagram.
Abstract: When a mobile network dynamically changes its point of attachment to the Internet, the various types of movements by a mobile router require handovers, and network mobility (NEMO) is concerned with the management of this movement of mobile networks. Accordingly, this paper investigates the mobile router movement patterns in NEMO network environments, and defines fast hierarchical NEMO handover scenarios based on classified movement patterns. Due to unexpected link breakdowns during the handover procedure, the NEMO handover requires additional latency and packet delivery costs depending on when the breaks occur. For the various handover failure cases, it is also essential to analyze these overhead costs to evaluate and compare the performance of a fast handover. In this paper, the overheads associated with a NEMO fast handover include the latency, buffering cost, and packet loss cost, all of which are formulated based on a timing diagram.
TL;DR: The proposed media access control provides frame aggregation with unequal error protection (UEP) and block acknowledgment (Blk-ACK) which can solve the problems of the existing MACs and guarantee the high quality of service.
Abstract: Millimeter-wave (mmWave) is highly focused as a powerful mean enabling to perform very high data transmission. This paper proposes the enhancement of media access control (MAC) for the mmWave WPAN. The existing MACs have limits to achieve high data transmission over 1---2 Gbps by reasons of the low frame transmission efficiency and the high overhead of signal exchanges. In addition, the transmitting frames need to be protected in a poor channel condition for the high quality of service. The proposed MAC provides frame aggregation with unequal error protection (UEP) and block acknowledgment (Blk-ACK), which can solve the problems of the existing MACs and guarantee the high quality of service. Our theoretical throughput analysis shows that the proposed MAC does the high throughput enhancement compared to the existing MACs and achieves the MAC throughput over 2Gbps in the mmWave WPAN.
TL;DR: Frequency Modulated UWB as radar can meet the requirements of typical biomedical applications such as Non-Invasive Heart and Respiration Rate Monitoring and the integration of sensing and communication using FM-UWB and radar technology so that a single device can be obtained for two different operational mode.
Abstract: UWB technology is a useful and safe new technology in the area of wireless body area network. There are many advantages of using UWB as a communication standard for biomedical applications. Due to very low radiated power (?41.3 dBm/MHz), low power consumption, good coexistence with the other existing instruments, Robustness to interference and multipath. Moreover, one specific UWB technology, namely Frequency Modulated (FM)-UWB, has also an important advantage, which make it even more convenient for medical applications, such as simple low cost design (FM, no receive LO, no carrier synchronization as in IR-UWB). UWB technology has been also proposed radar applications such as: Non-Invasive Heart and Respiration Rate Monitoring; Detection of Cardiac Arrhythmias; Detection of Pathological Respiratory Patterns, particularly in Sudden Infant Death Syndrome (SIDS) and Sleep Apnea; Multi-Patient Monitoring; Detection and Non-Invasive Imaging of Breast Tumors. However, pulsed radar are mainly used for these applications. The main issue that is addressed in this paper is the integration of sensing and communication using FM-UWB and radar technology so that a single device can be obtained for two different operational mode. We have show that FM-UWB as radar can meet the requirements of typical biomedical applications such as Non-Invasive Heart and Respiration Rate Monitoring. Advantages and challenges of this integration are shown. Future perspectives of this novel activity will be drawn.
TL;DR: An improved authentication procedure for the 3G-WLANs integrated networks that enables a WLAN user to get access to the3G packet switched services or to the public Internet through the 3Gs public land mobile network is proposed.
Abstract: The incorporation of Wireless Local Area Networks (WLANs) within the third generation (3G) networks materializes the next generation of mobile/wireless systems, named 3G-WLANs integrated networks. This paper proposes an improved authentication procedure for the 3G-WLANs integrated networks that enables a WLAN user to get access to the 3G packet switched services or to the public Internet through the 3G public land mobile network. The proposed procedure reduces significantly the authentication overhead compared to the legacy one, without compromising the provided security services. A security analysis of the proposed authentication procedure is elaborated that ensures the correctness of the authentication procedure, the provision of advanced security services and the elimination of possible attacks that may threaten the proposed authentication procedure. In addition, an energy cost analysis is carried out that compares the energy consumption induced by the legacy and the proposed authentication procedures. Finally, a communication cost analysis is provided that estimates the cost improvement of the proposed over the legacy authentication procedure.
TL;DR: Recent efforts in telehealth are addressed, including standards, system architectures, propagation models, and lower layer protocols for body area networks, and the use of cooperative transmission-based strategies for such wireless topologies are suggested.
Abstract: Telehealth is the use of electronic information and communication technology to deliver health and medical information and services over large and small distances. Broadband wireless services available today, along with more powerful and convenient handheld devices, will enable a transformational change in health management and healthcare with the introduction of real-time monitoring and timely responses to a wide array of patient needs. Further, a network of low-cost sensors and wireless systems help in creating constantly vigilant and pervasive monitoring capability at home and at work. This paper addresses recent efforts in this growing field, including standards, system architectures, propagation models, and lower layer protocols for body area networks. The paper also suggests the use of cooperative transmission-based strategies for such wireless topologies.
TL;DR: The proposed method aims at evaluating the various candidate configurations that a cognitive transmitter may operate in, by associating a capability e.g., achievable bit-rate, with each of these configurations, and increases the certainty about the configuration evaluations by considering past experience and knowledge through the use of Bayesian networks.
Abstract: This paper proposes enhancements to the channel(-state) estimation phase of a cognitive radio system. Cognitive radio devices have the ability to dynamically select their operating configurations, based on environment aspects, goals, profiles, preferences etc. The proposed method aims at evaluating the various candidate configurations that a cognitive transmitter may operate in, by associating a capability e.g., achievable bit-rate, with each of these configurations. It takes into account calculations of channel capacity provided by channel-state estimation information (CSI) and the sensed environment, and at the same time increases the certainty about the configuration evaluations by considering past experience and knowledge through the use of Bayesian networks. Results from comprehensive scenarios show the impact of our method on the behaviour of cognitive radio systems, whereas potential application and future work are identified.
TL;DR: A cross-layer based dynamically tuned queue length scheduler is presented in this paper, for the Downlink of multiuser WLAN systems with heterogeneous traffic requirements.
Abstract: The use of real-time delay-sensitive applications in wireless systems has significantly increased during the last years. Consequently, the demand to guarantee certain Quality of Service (QoS) is a challenging issue for the system's designers. A cross-layer based dynamically tuned queue length scheduler is presented in this paper, for the Downlink of multiuser WLAN systems with heterogeneous traffic requirements. An opportunistic scheduling algorithm is applied, while users from higher priority traffic classes are prioritized. A trade-off between the throughput maximization of the system and the guarantee of the users QoS requirements is obtained. Therefore the length of the queue is dynamically adjusted to select the appropriate conditions based on the operator requirements.
TL;DR: It will be shown in this paper that in case of non ideal channel knowledge and a limited accuracy in the channel matrix H estimation a reduced number of Eigenmodes in the precoding process will become an optimum and will lead into an increased BER performance.
Abstract: Multiple-input multiple-output (MIMO) based communication systems with precoding, bit-loading and equalization procedures are considered in this paper Applications of precoding schemes, which are based on Singular Value Decomposition (SVD) of the channel matrix H assume almost always ideal channel knowledge at the transmitter and/or receiver site This paper investigates an SVD based MIMO approach considering non ideal radio channel estimation results In any case the MIMO channel matrix H is decomposed into Eigenmodes In case of an ideal radio channel knowledge the SVD based precoding procedure, which is applied at the transmitter site, is going to consider all possible Eigenmodes which results in a perfect separation of all signals at the receive antenna output and into a minimum bit-error-rate (BER) It will be shown in this paper that in case of non ideal channel knowledge and a limited accuracy in the channel matrix H estimation a reduced number of Eigenmodes in the precoding process will become an optimum and will lead into an increased BER performance
TL;DR: In this paper, the authors proposed range-based sleep scheduling (RBSS) protocol which needs sensor-to-sensor distance but no location information, which attempts to approach an optimal sensor selection pattern that demands the fewest working (awake) sensors.
Abstract: Sleep scheduling in a wireless sensor network is the process of deciding which nodes are eligible to sleep (enter power-saving mode) after random deployment to conserve energy while retaining network coverage. Most existing approaches toward this problem require sensor's location information, which may be impractical considering costly locating overheads. This paper proposes range-based sleep scheduling (RBSS) protocol which needs sensor-to-sensor distance but no location information. RBSS attempts to approach an optimal sensor selection pattern that demands the fewest working (awake) sensors. Simulation results indicate that RBSS is comparable to its location-based counterpart in terms of coverage quality and the reduction of working sensors.
TL;DR: A prototype WBAN system that is implemented by using ultra-wideband technology and an experimental system that uses the developedWBAN system by combining with satellite communication in supporting remote medical treatment and healthcare.
Abstract: Wireless Body Area Network (WBAN) is expected to play an important role in supporting medical and healthcare services with increased convenience and comfort. One main advantage of WBAN is that it enables automatic biosignal collection in real time which is essential in medical treatment and healthcare vigilance. To harmonize with the strong demands from both medical and healthcare societies, and information and communications technology industries, IEEE 802 Standard Committee set up a task group of TG15.6 to develop an IEEE wireless standard on WBAN. In this paper, we first review the main activities of TG15.6 with the updated status. Then, we present a prototype WBAN system that is implemented by using ultra-wideband technology. Multi-hop mechanism is adopted to guarantee reliable connection. Finally, we describe an experimental system that uses the developed WBAN system by combining with satellite communication in supporting remote medical treatment and healthcare. In case of less of medical resources such as in emergency, in rural or isolated areas, such a system is important in sending the corresponding biosignal to a remote hospital in real time to help patient management. The relative delay of WBAN data delivery via satellite is measured which is dependent on the satellite link capacity.
TL;DR: An adaptive beacon scheduling mechanism using power control, cluster grouping, and the group identifier (GID) in cluster-tree WPANs is presented, designed such that all of the sensing devices send the measured received power level back to their cluster heads (CHs), thus enabling them to adjust their transmission power level after the construction of the topology.
Abstract: This paper presents an adaptive beacon scheduling mechanism using power control in cluster-tree network. We consider the emerging low-rate wireless personal area networks (LR-WPANs) technology as specified in the IEEE 802.15.4 standard that can support environmental monitoring applications. Node clustering is a useful topology management approach to reduce channel contention and improve the network lifetime in wireless sensor networks. A cluster-tree network conforming to the IEEE 802.15.4 standard is formed by several coordinators that periodically send beacon frames to the nodes of their cluster. However, if these periodic beacon frames are sent without any particular scheduling, they will collide with each other and those nodes that wait for them will lose synchronization with their coordinators. The purpose of this paper is to overcome this problem by proposing an adaptive beacon scheduling mechanism using power control, cluster grouping, and the group identifier (GID) in cluster-tree WPANs. This mechanism is designed such that all of the sensing devices send the measured received power level back to their cluster heads (CHs), thus enabling them to adjust their transmission power level after the construction of the topology. Following this, the PAN coordinator divides all of the CHs into several cluster groups (CGs) in order to transmit their beacon frames simultaneously without encountering any direct or indirect beacon frame collision problems. The PAN coordinator selects the group heads (GHs) and assigns the GID for each cluster group. In addition, the PAN coordinator controls the beacon transmission time of all of the CHs and GHs in the CGs using the GID information located in the beacon frame of the PAN coordinator in order to avoid beacon frame collisions. Accordingly, the overall lifetime of the network in cluster-tree WPANs is prolonged by solving the problem of beacon frame collisions. We evaluated the performance of our scheme through a mathematical analysis and a series of simulations using the Network Simulator 2 (NS-2).
TL;DR: An approach to performance evaluation and capacity planning is presented, based on a high-level system description formalism, which can be readily extracted from a system design, in assessing the design of a content adaptation framework being developed under the auspices of the virtual centre in mobile communications.
Abstract: In the new era of wireless, mobile connectivity the possibilities of anything, anytime, anywhere access are becoming a reality. In order to deliver services and content to users in a variety of contexts, content adaptation strategies need to be developed and assessed. In this paper we present an approach to performance evaluation and capacity planning, based on a high-level system description formalism, which can be readily extracted from a system design. We demonstrate its usefulness in assessing the design of a content adaptation framework being developed under the auspices of the virtual centre in mobile communications.
TL;DR: The simulation results show that the proposed CBDSM scheme effectively improves the spectrum utilization and the profit of operators while it reduces the mutual interference between wireless networks to a tolerable level.
Abstract: Future wireless systems are expected to be characterized by the coexistence of different radio access technologies (RATs) resulting in complex heterogeneous wireless environments. In parallel with this, the tremendous demand for spectrum has inspired the requirement of dynamic spectrum management (DSM). This paper aims at designing a cell based dynamic spectrum management (CBDSM) scheme to enhance the spectrum utilization and maximize the profit of operators in wireless heterogeneous networks. The system architecture and the functional modules supporting the CBDSM scheme are designed. As a fundamental issue in spectrum management, the inter-system interference issue is solved in the proposed CBDSM scheme. Furthermore, game theory, which is a potential tool for studying the distributed autonomous resource optimization algorithms, is applied to design a spectrum trading algorithm enabling the heterogeneous wireless networks to dynamically trade spectrum and to share the profit. In the algorithm, we take into account the economic value of the spectrum of wireless systems in order to guarantee the rationality for the spectrum trading. The simulation results show that the proposed CBDSM scheme effectively improves the spectrum utilization and the profit of operators while it reduces the mutual interference between wireless networks to a tolerable level.
TL;DR: This paper proposes an efficient slot reservation MAC protocol to reduce energy consumption and to make transmission more efficient in data gathering wireless sensor networks and results show that the protocol provides high throughput, low delivery latency and low energy consumption compared to other methods.
Abstract: Wireless sensor networks use battery-operated computing and sensing devices. Because of the limitation of battery power in the sensor nodes, energy conservation is a crucial issue in wireless sensor networks. Consequently, there is much literature presenting energy-efficient MAC protocols based on active/sleep duty cycle mechanisms to conserve energy. Convergecast is a common communication pattern across many sensor network applications featuring data gathering from many different source nodes to a single sink node. This leads to high data collision rates, high energy consumption, and low throughput near the sink node. This paper proposes an efficient slot reservation MAC protocol to reduce energy consumption and to make transmission more efficient in data gathering wireless sensor networks. The simulation results show that our protocol provides high throughput, low delivery latency and low energy consumption compared to other methods.
TL;DR: This contribution deals with the proposal of a new modulation technique ensuring secure communication in a full wireless environment and shows that the performance of the proposed scheme yields the advantage of intrinsic security, i.e., the mutual information cannot be physically demodulated or denied by a third terminal.
Abstract: Due to the enormous spreading of applied wireless networks, security is actually one of the most important issues for telecommunications. One of the main issue in the field of securing wireless information exchanging is the initial common knowledge between source and destination. A shared secret is normally mandatory in order to decide the encryption (algorithm or code or key) of the information stream. It is usual to exchange this common a priori knowledge by using a “secure” channel. Nowadays a secure wireless channel is not possible. In fact normally the common a priori knowledge is already established (but this is not secure) or by using a non-radio channel (that implies a waste of time and resource). This contribution deals with the proposal of a new modulation technique ensuring secure communication in a full wireless environment. The information is modulated, at physical layer, by the thermal noise experienced by the link between two terminals. A loop scheme is designed for unique recovering of mutual information. The probability of error/detection is analytically derived for the legal users and for the third unwanted listener (passive or active attacker). Both the case of passive and active attacks have also been implemented and simulated by using Matlab-Simulink software. The analytical results have been compared to the simulated ones. All the results show that the performance of the proposed scheme yields the advantage of intrinsic security, i.e., the mutual information cannot be physically demodulated (passive attack) or denied (active attack) by a third terminal.
TL;DR: A finding of the analysis is that optimization techniques for movement detection and duplicate address detection are essential to shortening HMIPv6 handover latency and increasing the benefit of HMIP v6.
Abstract: There has been a rapid growth in the need to support mobile nodes in IPv6-based networks. IETF has completed to standardize Mobile IPv6 (MIPv6) and Hierarchical Mobile IPv6 (HMIPv6) for supporting IPv6 mobility. Even though existing literatures have asserted that HMIPv6 generally improves MIPv6 in terms of handover speed, they do not carefully consider the details of the whole handover procedures. In this paper, based on the current IETF standards of both MIPv6 and HMIPv6, we conduct a comprehensive study of all IP-level handover procedures: movement detection, duplicate address detection, and location registration. Based on this study, we provide a mathematical analysis on MIPv6 and HMIPv6 performance in terms of handover speed. From the analysis, we reveal that the average HMIPv6 handover latency is not always lower than the average MIPv6 handover latency. Furthermore, even the intra-domain handover latency of HMIPv6 is not reduced much compared with MIPv6 handover latency. A finding of our analysis is that optimization techniques for movement detection and duplicate address detection are essential to shortening HMIPv6 handover latency and increasing the benefit of HMIPv6.
TL;DR: An artificial neural network (ANN) channel estimation technique based on levenberg-marquardt training algorithm is proposed as an alternative to pilot basedChannel estimation technique for OFDM systems over Rayleigh fading channels.
Abstract: The many advantages responsible for the widespread application of orthogonal frequency division multiplexing (OFDM) systems are limited by the multipath fading. In OFDM systems, channel estimation is carried out by transmitting pilot symbols generally. In this paper, we propose an artificial neural network (ANN) channel estimation technique based on levenberg-marquardt training algorithm as an alternative to pilot based channel estimation technique for OFDM systems over Rayleigh fading channels. In proposed technique, there are no pilot symbols which added to OFDM. Therefore, this technique is more bandwidth efficient compared to pilot-based channel estimation techniques. Also, this technique is making full use of the learning property of neural network. By using this feature, there is no need of any matrix computation and the proposed technique is less complex than the pilot based techniques. Simulation results show that ANN based channel estimator gives better results compared to the pilot based channel estimator for OFDM systems over Rayleigh fading channel.
TL;DR: Simulation results show that JBSF typically performs better than SBS if the inter-cluster delay parameter (K) is not selected appropriately for SBS, and even at sampling rates much smaller than the Nyquist rate, ranging accuracies can be obtained using a non-coherent UWB receiver.
Abstract: Non-coherent ultra-wideband (UWB) receivers offer an attractive low-complexity solution to ranging with UWB radios They use a simple receiver architecture that can operate at very low sampling rates compared to the Nyquist rate In this paper, time-of-arrival (TOA) estimation performances of two different searchback algorithms for non-coherent impulse radio UWB systems are analyzed: jump back and search forward (JBSF) and serial backward search (SBS) Average ranging errors for both algorithms are formulated using noise-based ranging thresholds and at sub-Nyquist sampling rates For JBSF, a lower bound on the average ranging error is obtained using an error-minimizing threshold Also, a semi-analytic technique for the selection of the searchback window length is presented For SBS, noise-based threshold selection for both single-cluster and multi-cluster channels are introduced Computer simulations in IEEE 802154a channels provide insights on the selection of some of the critical parameters for accurate ranging The simulation results show that JBSF typically performs better than SBS if the inter-cluster delay parameter (K) is not selected appropriately for SBS In both cases, it is shown that even at sampling rates much smaller than the Nyquist rate, ranging accuracies on the order of 33 cm can be obtained using a non-coherent UWB receiver
TL;DR: A unified framework that exploits the physical channel properties and multi-user diversity gain of WMNs and by performing intelligent route selection and connection admission control provides both QoS and GoS to a variety of underlying applications is proposed.
Abstract: Cross-layer design for quality of service (QoS) in wireless mesh networks (WMNs) has attracted much research interest recently. Such networks are expected to support various types of applications with different and multiple QoS and grade-of-service (GoS) requirements. In order to achieve this, several key technologies spanning all layers, from physical up to network layer, have to be exploited and novel algorithms for harmonic and efficient layer interaction must be designed. Unfortunately most of the existing works on cross-layer design focus on the interaction of up to two layers while the GoS concept in WMNs has been overlooked. In this paper, we propose a unified framework that exploits the physical channel properties and multi-user diversity gain of WMNs and by performing intelligent route selection and connection admission control provides both QoS and GoS to a variety of underlying applications. Extensive simulation results show that our proposed framework can successfully satisfy multiple QoS requirements while it achieves higher network throughput and lower outage as compared to other scheduling, routing and admission control schemes.