Showing papers in "IEEE Vehicular Technology Magazine in 2007"
TL;DR: The research challenge of routing in VANETs is discussed and recent routing protocols and related mobility models for VANets are surveyed.
Abstract: Vehicular ad hoc network (VANET) is an emerging new technology integrating ad hoc network, wireless LAN (WLAN) and cellular technology to achieve intelligent inter-vehicle communications and improve road traffic safety and efficiency. VANETs are distinguished from other kinds of ad hoc networks by their hybrid network architectures, node movement characteristics, and new application scenarios. Therefore, VANETs pose many unique networking research challenges, and the design of an efficient routing protocol for VANETs is very crucial. In this article, we discuss the research challenge of routing in VANETs and survey recent routing protocols and related mobility models for VANETs.
1,147Â citations
TL;DR: This paper details design tradeoffs for algorithms in the 60 GHz physical layer including modulation, equalization, and space-time processing and considers the limitations in circuit design, characteristics of the effective wireless channel, and performance requirements to support current and next generation 60 GHz wireless communication applications.
Abstract: Multiple GHz of internationally available, unlicensed spectrum surrounding the 60 GHz carrier frequency has the ability to accommodate high-throughput wireless communications. While the size and availability of this free spectrum make it very attractive for wireless applications, 60 GHz implementations must overcome many challenges. For example, the high attenuation and directional nature of the 60 GHz wireless channel as well as limited gain amplifiers and excessive phase noise in 60 GHz transceivers are explicit implementation difficulties. The challenges associated with this channel motivate commercial deployment of short-range wireless local area networks, wireless personal area networks, and vehicular networks. In this paper we detail design tradeoffs for algorithms in the 60 GHz physical layer including modulation, equalization, and space-time processing. The discussion is enhanced by considering the limitations in circuit design, characteristics of the effective wireless channel (including antennas), and performance requirements to support current and next generation 60 GHz wireless communication applications.
592Â citations
TL;DR: The packet error rate (PER) for each model, measured with an emulator and an 802.11p wireless access in vehicular environments (WAVE) prototype, is presented.
Abstract: Three vehicle-to-vehicle (V2V) models and three roadside-to-vehicle (RTV) models, each suitable for RF channel emulation and based on measurements at 5.9 GHz, are presented. Each model captures the joint Doppler-delay characteristics of a different environment. The packet error rate (PER) for each model, measured with an emulator and an 802.11p wireless access in vehicular environments (WAVE) prototype, is presented.
316Â citations
TL;DR: The design considerations and various new and promising design concepts for the synchronization channel are presented and some specific solutions are evaluated and numerical performance results are provided.
Abstract: This paper reviews and presents the latest results in the cell search issue of the 3GPP Long Term Evolution (LTE) systems. Cell Search is a basic function of any cellular system, during which process time and frequency synchronization between the mobile terminal and the network is achieved. Such synchronization is especially important for 3GPP Long Term Evolution systems, which rely heavily on the orthogonality of the uplink and downlink transmission and reception to optimize the radio link performance. As in conventional cellular systems, the mobile terminal in an LTE system acquires time and frequency synchronization by processing the synchronization channel. Design of the synchronization channel is being developed within the standardization activities of 3GPP Long Term Evolution and is still evolving. In this paper, we present the design considerations and various new and promising design concepts for the synchronization channel. We evaluate some specific solutions and provide numerical performance results.
108Â citations
TL;DR: A set of solutions, implemented respectively at the session and network layers, for shortening the handover delays and/or providing session continuity in case of macro-handover in IMS-based networks are presented.
Abstract: With the introduction of terminals that support multiple access technologies, macro-mobility and roaming are becoming even more important functionalities: it is expected that mobile terminals will handover between heterogeneous networks in order to extend coverage or to get connectivity to faster and/or cheaper access technologies. Access and session control must be guaranteed when roaming across different administrative domains. The 3GPP IP multimedia subsystem (IMS) is the first platform standardized towards network-independent access and session control. However, the current IMS specifications do not allow for any change of the user's IP address during a session, which prevents seamless mid-session macro-handover. In this paper, we present and compare a set of solutions, implemented respectively at the session and network layers, for shortening the handover delays and/or providing session continuity in case of macro-handover in IMS-based networks. Since one of the main functions of IMS is quality of service (QoS) negotiation and the control of legacy interfaces to the access networks for QoS provisioning, special attention is given to the discussions of the QoS re-negotiation procedures during such handover cases.
42Â citations
TL;DR: The investigated design consists of two copper coils, each a self-resonant system that fills the space around it with a non-radiative magnetic field oscillating at MHz frequencies.
Abstract: The investigated design consists of two copper coils, each a self-resonant system. One of the coils, attached to the power source, is the sending unit. Instead of irradiating the environment with electromagnetic waves, it fills the space around it with a non-radiative magnetic field oscillating at MHz frequencies.
38Â citations
TL;DR: This work proposes and analyzes an opportunistic-driven adaptive radio resource manage merit (OPRAM) scheme that achieves tin- target traffic safety performance and efficiently uses the transmission and channel resources.
Abstract: Vehicle-to-vehicle and vehicle-to infrastructure wireless systems are currently under development to improve the traffic safety and efficiency while providing Internet connectivity on the move. A widespread adoption of these wireless vehicular communication technologies will require efficient use of the radio channel resources. To this end, this work proposes and analyzes an opportunistic-driven adaptive radio resource manage merit (OPRAM) scheme that achieves tin- target traffic safety performance and efficiently uses the transmission and channel resources.
35Â citations
TL;DR: These results demonstrate that a COTS 802.11 implementation can correctly decode many packets under collision due to physical layer capture and can serve as a reference scenario for validation of network simulators.
Abstract: Dedicated short range communications (DSRC) enable novel automotive safety applications such as an extended electronic brake light (EEBL) or intersection collision avoidance (ICA). These applications require reliable wireless communications even in scenarios with very high vehicle density, where these networks are primarily interference-limited. Given the uncertainties associated with current simulation models, particularly their interference models, it is critical to experimentally validate network performance for such scenarios. Towards this goal, we present a systematic, large- scale experimental study of packet delivery rates (PDRs) in a dense environment of 802.11 transmitters. We show that even with 100 transmitters in communication range with a frame size of 128 B and a bit-rate of 6 Mb/s, 1) most receivers can decode over 1500 packets per second (pps) in a saturated network, which corresponds to a PDR of 45% and 2) the mean PDR, for 10 pps per node workload that emulates vehicular safety applications, is about 95%. These results demonstrate that a COTS 802.11 implementation can correctly decode many packets under collision due to physical layer capture (PLC) and can serve as a reference scenario for validation of network simulators.
33Â citations
TL;DR: This IMS service framework can be used to implement new services, but its main strength might eventually be in its ability to seamlessly integrate existing services and deliver them to end-users in an optimized manner.
Abstract: While IMS was specified and is often presented as a fairly complex core network, it can also be perceived as a very powerful and simple service framework. This IMS service framework can be used to implement new services, but its main strength might eventually be in its ability to seamlessly integrate existing services and deliver them to end-users in an optimized manner.
32Â citations
TL;DR: A novel adaptive service creation solution called POETRY is presented that takes advantages of two promising techniques: PBM (Policy-based Management) and MDA (Model-driven Architecture).
Abstract: This article advocates the shift of the adaptive service engineering attention from the external service execution environment to the internal service logic itself. This article presents a novel adaptive service creation solution called POETRY that takes advantages of two promising techniques: PBM (Policy-based Management) and MDA (Model-driven Architecture). In particular, the POETRY service creation framework has investigated the thought of utilizing a policy-based management method to describe and control the internal logic of adaptive services and the method of utilizing MDA models to describe the adaptive service information model. The design details and operations of POETRY are presented and showcased via a typical adaptive service scenario.
24Â citations
TL;DR: How good the current wireless access network technologies are for usage in combination with IMS services is evaluated to give an indication as to what networks will be most applicable for usage, particularly for a vehicular environment.
Abstract: The IP Multimedia Subsystem (IMS) as defined by the 3GPP emerges as blueprint for a central architecture to provide Next Generation Network (NGN) services. As overlay architecture for IP based access networks, it provides standardized interfaces to services which will merge the advantages of traditional telephony networks with the benefits of Internet services. This paper will evaluate how good the current wireless access network technologies are for usage in combination with IMS services. Based upon a reference implementation of IMS core elements, the Open IMS Core, measurements were carried out on signaling to give an indication as to what networks will be most applicable for usage, particularly for a vehicular environment.
TL;DR: This paper describes work being undertaken within HP's IMS Experience Center to validate a horizontal service delivery architecture for next-generation IP multimedia applications.
Abstract: The IP multimedia subsystem (IMS) standard is being widely adopted by both wireline and wireless service providers to support the next wave of multimedia communication applications. As currently defined, that IMS standard proposes a detailed architecture for the transport and control layers of the next-generation telecommunication networks, but leaves many questions unanswered on how the application layer should be structured. A more structured approach to service delivery will be required in order to deliver new multi-media applications in an efficient and cost-effective way. An approach based on service delivery platform (SDP) proposes a layered service architecture, with a strong emphasis on re-use of common service enablers and on open APIs. This paper describes work being undertaken within HP's IMS Experience Center to validate a horizontal service delivery architecture for next-generation IP multimedia applications.
TL;DR: This work introduces a novel framework for the management of services in wireless environments, considering the diverse requirements and conditions and results indicate that the policy-based approach offers a flexible framework where both business and user expectations are met.
Abstract: Nowadays, services targeting home and business users, such as Internet access, digital television or online entertainment are taken for granted. However, our lifestyle creates the need for extending the reach of such services but also the need for new ones, targeted to people on the move. With complex wireless networks forming around us and a new range of services becoming available, an enhanced service management paradigm is required. This work introduces a novel framework for the management of services in wireless environments, considering the diverse requirements and conditions. Using a wireless media service as a case study, simulation results indicate that our policy-based approach offers a flexible framework where both business and user expectations are met. User preferences guide service customization while statistical processing of user requests directs service adaptation.
TL;DR: Tradeoffs between implementation complexity and accuracy of several stochastic channel models for lite V2V environment are discussed, and spread-spectrum system performance attained using these channel models is addressed.
Abstract: Vehicle-to-vehicle (V2V) communications have drawn much attention in recent years. In this article, we discuss tradeoffs between implementation complexity and accuracy of several stochastic channel models for lite V2V environment, and then address spread-spectrum system performance attained using these channel models. Two different propagation environments are considered: urban and open areas (highways). The necessity of employing nonstationary channel models to accurately represent the channel is substantiated by comparing stationary and nonstationary empirical model outputs with measured data. A framework to compare single-carrier direct sequence code division multiple access (SC-DS-CDMA) and mul- ticarrier DS-CDMA (MC-DS-CDMA) performance in V2V channels is presented, and bit error ratio (BER) performance of the schemes is provided for the two channels Our comparison of single- and multiuser performance shows that MC-DS-CDMA performs better than SC-DS-CDMA in both Y2V environments.
TL;DR: This paper presents and analyses different CAM selection policies in order to derive the best-suited strategy in terms of system performance and proposes an optimal policy, based on traffic type and direction (uplink or downlink), which confirms the good performance of this new selection policy.
Abstract: The appearance of the 802.11e standard made the 802.11 wireless local area networks (WLANs) capable of providing different levels of quality of service (QoS). This standard defines two new channel access mechanisms (CAMs), namely the enhanced distributed channel access (EDCA) and the HCF controlled channel access (HCCA). The introduction of two CAMs increases the complexity of traffic management, since now not only the available resources have to be distributed, but also the optimal CAM for each data flow has to be selected. However, the best CAM selection algorithm is still not clear. This paper presents and analyses different CAM selection policies in order to derive the best-suited strategy in terms of system performance. From this study, an optimal policy, based on traffic type and direction (uplink or downlink), is proposed. The best user QoS satisfaction shown in the results confirms the good performance of this new selection policy.
TL;DR: This article investigates the properties of several non-Jakes Doppler spectra proposed for the vehicle-to-vehicle nonisotropic scattering environment of the open highway with results that match well with the theoretical ideal channel.
Abstract: This article investigates the properties of several non-Jakes Doppler spectra proposed for the vehicle-to-vehicle nonisotropic scattering environment of the open highway. Expressions for the ideal model correlations, level-crossing rates, and average fade durations are derived. The classic Clarke channel model is modified to generate fading signals corresponding to the nonisotropic scattering profiles. The simulation results match well with the theoretical ideal channel.
TL;DR: This paper first analyzes the functional and protocol level differences between IMS and MMD architectures, then articulate several deployment architectural alternatives for 3GPP2 MMD networks and finally analyze the pros and cons of each architecture.
Abstract: Mobile and fixed operators are offering broadband access to the Internet by either adding wireless access to their existing core networks (eg, CDMA IxEVDO GPRS, and WiFi) or continuing to evolve existing broadband infrastructures (eg, DSL, Cable and FTTx) Consequently, IMS and MMD architectures as defined by 3GPP and 3GPP2 are becoming increasingly important to network operators, in particular, for offering ubiquitous service and seamless mobility to end users, along with management and control Although 3GPP2 MMD architecture has adopted most of the 3GPP IMS core functionalities and interfaces, it added several other unique functional components and interfaces to fit the specific need of CDMA2000 access networks Therefore, it is important to understand the gaps and issues associated with the 3GPP2 MMD architecture with regard to the 3GPP IMS architecture In this paper, we first analyze the functional and protocol level differences between IMS and MMD architectures Based on our analysis, we then articulate several deployment architectural alternatives for 3GPP2 MMD networks and finally analyze the pros and cons of each architecture
TL;DR: This paper outlines a PTC security framework utilizing using a certificate based trust management system and over the air re-keying (OTAR) to support interoperation.
Abstract: Positive train control (PTC) is an electronic system that enforces activities such as train separation, speed enforcement, and roadway worker protection essential to operate railroads safely and efficiently. Vehicular ad-hoc networks (VANETS) provide distributed real time communication of traffic hazards and road conditions among vehicles in a radio line of sight. Communicating PTC VANET systems offer the potential to reduce highway rail intersection (HRI) collisions by communicating train movement information to highway vehicles. For this to occur, different PTC systems must securely interoperate with each other. This outlines a PTC security framework utilizing using a certificate based trust management system and over the air re-keying (OTAR) to support interoperation.
TL;DR: A policy-based radio resource management model for decision sharing between the network and the mobile terminals in the context of composite networks where policies are chosen automatically act aiding to the variations of the environment conditions and the operator strategy is presented.
Abstract: This paper presents a policy-based radio resource management model for decision sharing between the network and the mobile terminals in the context of composite networks. One of the key issues discussed in this paper is the distribution of Radio Resource Management (RRM) decision making between the network and the mobile terminal. IEEE P1900.4 standard project proposes a policy-based radio resource usage scheme, where the decision-making is shared between the network and the mobile terminals. The network orients the mobile terminals decisions by sending rules and constraints. Mobile terminals choose the most appropriate action to their own Quality of service (QoS) objectives, within the action set allowed by the network. We define detailed scenarios illustrating this model. In addition, we propose a model where policies are chosen automatically act aiding to the variations of the environment conditions and the operator strategy. For this purpose, we define a policy database that stores the different environment configurations matched with the appropriate policies. Environment configurations are first classified. Then for each environment class an optimization algorithm finds the policy that fits the operator objectives.
TL;DR: Reports on the market for ultra mobile broadband services are provided to help decision-makers and marketers better understand the market and take action to improve the quality and quantity of services offered.
Abstract: Reports on the market for ultra mobile broadband services.
TL;DR: In this paper, formal mobile WiMAX certification testing were discussed, as well as, 4G mobile communications and mobile TV technologies.
Abstract: In this paper, formal mobile WiMAX certification testing were discussed, as well as, 4G mobile communications and mobile TV technologies.
TL;DR: It looks like adaptive cruise control is getting a cool reception in the US, but one theory why it is not more popular is that it is frustrating to use.
Abstract: Some of the most innovative automotive technology is slowly dying off. Sometimes even the most impressive tech fails to sell. For example, it looks like adaptive cruise control is getting a cool reception in the US. One theory why it's not more popular: "once you set your speed, if someone cuts in front of you, the adaptive cruise control slows your car down, which leaves room for someone else to cut in front of you, which slows your car again. Before you know it, everyone on the road is passing you. Unless you're in very light traffic conditions, adaptive cruise control is frustrating to use".
TL;DR: GSM is today a global standard deployed by more than 700 operators in over 200 countries and makes up 85% of the global mobile services market, which accounts for about 1.6% of global GDP.
Abstract: This article reports on the celebration of the 20th anniversary of GSM in mobile communication.GSM is today a global standard deployed by more than 700 operators in over 200 countries. There are currently more than 2.6 billion subscribers - more than 40% of the world's population - using a GSM device. Today, the GSM family of technologies makes up 85% of the global mobile services market, which accounts for about 1.6% of global GDP.
TL;DR: Reports on new rail lines for South Africa as well as other transportations systems around the world.
Abstract: Reports on new rail lines for South Africa as well as other transportations systems around the world.
TL;DR: Validation through indicative simulated scenarios shows that the proposed evaluation process can be used to derive robust policy rules to tackle with the demand fluctuations, service diversities and power/interference constraints in a heterogeneous B3G environment.
Abstract: 'The unstoppable desire and need for ubiquitous wireless access and high quality provision of pioneer multimedia brought about a remarkable proliferation of wireless networks and services, reflected in the BeyondSG (B3G) world. In such a versatile environment, legacy management functionalities are hindered by high spatial and temporal context variations. The idea of policy based management that governs the behavior of managed elements by using policy rules, promises to reduce complexity and operating costs while at the same time satisfy service level agreements and offer wise resource usage In this paper we focus on 3G CDMA-based systems, which are expected to be indispensable part of wireless B3G infrastructures, and ire first define and format policies for the allocation of demand (users per serine, location) to available carrier frequencies Then, an evaluation process to access those policies according to certain objectives is proposed. Validation through indicative simulated scenarios shows that the proposed evaluation process can be used to derive robust policy rules to tackle with the demand fluctuations, service diversities and power/interference constraints in a heterogeneous B3G environment.
TL;DR: This paper describes a framework for consent- based communications in SIP that allows users to grant or deny SIP entities permission to communicate with those users.
Abstract: This paper describes a framework for consent- based communications in SIP. This framework allows users to grant or deny SIP entities permission to communicate with those users. Consent-based communications prevent some types of amplification-based denial of service attacks and can be used to alleviate the effects of spam in SIP. This paper also presents the results of our experiments implementing this framework.