By Topic

Date Nov. 30 2009-Dec. 4 2009

Filter Results

Displaying Results 1 - 25 of 105
  • [Title page]

    Publication Year: 2009 , Page(s): i
    Save to Project icon | Request Permissions | PDF file iconPDF (93 KB)  
    Freely Available from IEEE
  • [Copyright notice]

    Publication Year: 2009 , Page(s): ii
    Save to Project icon | Request Permissions | PDF file iconPDF (70 KB)  
    Freely Available from IEEE
  • List of papers

    Publication Year: 2009 , Page(s): iii
    Save to Project icon | Request Permissions | PDF file iconPDF (162 KB)  
    Freely Available from IEEE
  • A Concept for Efficient System-Level Simulations of OFDMA Systems with Proportional Fair Fast Scheduling

    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (206 KB) |  | HTML iconHTML  

    System-level simulations of packet-based orthogonal frequency-division multiple access (OFDMA) cellular networks require a proper consideration of the channel-dependent fast fading/scheduling in order to produce meaningful results. However, generating the time and frequency selective fast fading channels and performing detailed channel-adaptive scheduling for each user in a multi-cellular system is computationally too expensive in most system-level simulations. To this end, we propose an efficient mapping technique that allows to accurately characterize the performance of the fast-scheduling system using two parameters: the average effective post-scheduling SINR gain and the ratio of allocated resources, both conditioned on the SINR and the velocity of a user in a scenario defined by the number of co-scheduled users. To derive these parameters for different numbers of users at different velocities and SINR levels, we perform detailed link level simulations including fast scheduling for the downlink of a long term evolution (LTE) system. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Discussion of Socio-Economic Management and Incentives for the Future Internet

    Publication Year: 2009 , Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (227 KB) |  | HTML iconHTML  

    This paper outlines the outcome of a socioeconomics (SE) and incentives work group during the "Management of the Future Internet" seminar, held in Dagstuhl, Germany. This covers an indication of key questions and issues, which are classified as important for next steps in network management. Furthermore, the process of dealing with aspects of "Socio-economic Management" is discussed, which determines a hybrid and innovative approach besides traditional network management approaches. This determines a network management in which control is delegated via socio-economic means and to a certain extent to the user and provider with the goal to maximize the overall social welfare and the networks technical efficiency at the same time. This is refined by a set of SE-driven management mechanisms, the discussion of abstract user/network interfaces (stakeholder relations), and an example case for managing overlay traffic in such a network management system. Finally, based on a set of ideal SE requirements derived from the analysis of existing approaches, a set of preliminary conclusions is drawn. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Game-Theoretic Framework for Dynamic Spectrum Leasing (DSL) in Cognitive Radios

    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (179 KB) |  | HTML iconHTML  

    In this paper we develop a game-theoretic framework for dynamic spectrum leasing in a cognitive radio network. Dynamic Spectrum Leasing, or DSL for short, is a new paradigm for efficient spectrum sharing in cognitive radio networks that was proposed recently. DSL allows the primary users to actively encourage, or discourage, secondary access depending on their instantaneous Quality-of-Service (QoS) requirements and affordable power constraints. Secondary users, on the other hand, attempt to maximize throughput, or any other suitably chosen reward function, opportunistically, while not violating the interference limit set by the primary users. In this paper, we have proposed further generalization to the primary user utility function defined and a new utility function for the secondary users. We establish the conditions on the primary and secondary user utility functions so that the DSL game has desired equilibrium properties. Simulation results show the system behavior and performance at the equilibrium and also help to identify suitable system design parameters. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Joint Radio and Channel Assignment (JRCA) Scheme for 802.11-Based Wireless Mesh Networks

    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (266 KB) |  | HTML iconHTML  

    Wireless mesh network (WMN) is a promising technology for broadband Internet access due to its low cost, ease of deployment, increased coverage, and robustness. Equipping each mesh router with multiple radios can greatly improve the capacity of WMNs since the radios at each node can simultaneously transmit data on orthogonal channels. Channel assignment is an important problem in multi-radio multi-channel WMNs where the goal is to assign a channel to each radio so that the resulting network topology is connected and the network capacity is maximized. Various channel assignment schemes assume that the number of radios at each node is given, but how this number is determined is not specified. In this work, we propose a joint radio and channel assignment (JRCA) algorithm that determines the number of radios required at each node based on the traffic demand and produces the channel assignment for each radio to minimize the interference among the links operating on the same channel. Thus, our algorithm can produce a network configuration that meets the customer demand and maximize the network capacity. Simulation results show that JRCA can achieve higher throughput with fewer radios at the network nodes, compared to fixed-radio WMNs. In addition to this, we believe that our work, to our best knowledge, is the first of its kind that couples the problem of radio allocation and channel assignment in a joint manner. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Model-Based Techno-Economic Comparison of Optical Access Technologies

    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (305 KB) |  | HTML iconHTML  

    The need for broadband Internet services requires the deployment of high-capacity access networks. In the next years, network operators will invest high amounts of money to deploy new fiber-based systems. In this paper we present a techno-economic calculation model and case-study results to compare three diverse access technologies: GPON, Active Optical Networking, and Point-to-Point optical networks. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A New Markov Model for Evaluating the ALR Dual-Threshold Policy

    Publication Year: 2009 , Page(s): 1 - 5
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB) |  | HTML iconHTML  

    The paper proposes the analysis of the Dual-Threshold Policy, used by Adaptive Link Rate (ALR). In particular, the paper firstly presents a new Markov model of the Dual-Threshold Policy. The new features of the model concern its ability to take into account the rate switching times and the buffer size of the Ethernet Network Interface Controller (NIC). Secondly, we have evaluated the performance of the Dual-Threshold Policy by means of the proposed model and of a new power consumption model of an Ethernet NIC implementing ALR. As performance parameter, we have considered the power savings, the packet loss probability, the mean packet delay, and the oscillation of link data rate. The results show that high rate switching times can make ALR unprofitable and that the current NICs buffer size is unsuitable for ALR. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A New Multi-Path Routing Methodology Based on Logit Type Assignment

    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (188 KB) |  | HTML iconHTML  

    We present a new multi-path routing methodology called MLB-routing based on multinomial logit model, which is well known as the random utility theory. The key concept of the study is to incorporate multiple paths from same origin to destination, and distribute packets followed by the multinomial logit type probability. Since MLB-routing is pure multi-path routing, it reduce the severe convergence to same links and increases the bandwidth utilization in the network. Compared to the existing multi-path routing schemes that select pre-determined alternate paths, the proposed method can dynamically distribute packets to every possible paths and thus is more efficient than them. Furthermore, it should be mentioned that this methodology could be implemented as both link-state protocol and distance-vector protocol. Therefore, it has enough affinity for present Internet mechanism. Using simulations, we have also shown that this methodology produces more efficient use of network and causes significant improvements in end-to-end delays and jitter times. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Reduced-State-Space Markov Chain Monte Carlo Method for Iterative Spatial Multiplexing MIMO

    Publication Year: 2009 , Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (177 KB) |  | HTML iconHTML  

    Markov Chain Monte Carlo (MCMC) method applied as Multiple-Input-Multiple-Output (MIMO) detector has shown near capacity performance. However, the conventional MCMC method suffers from an error floor in the high signal-to-noise (SNR) region. This paper proposes a novel robust reduced-state-space MCMC (RSS-MCMC) method, which utilizes the a priori information for the first time to qualify the reliable decoded bits from the entire signal space. The new robust MCMC method is developed to deal with the unreliable bits by using the reliably decoded bit information to cancel the interference that they generate. The performance comparison shows that the new technique has improved performance compared to the conventional approach, and further complexity reduction can be obtained with the assistance of the a priori information. Furthermore, the complexity and performance tradeoff of the new method can be optimized for practical realizations. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Trust Evaluation Model for Future Peer-to-peer E-Commerce Environments

    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (151 KB) |  | HTML iconHTML  

    Due to the flexibility and freedom of the P2P e-commerce environment, peers often make transactions with other unknown peers, the trust evaluation becomes critical. Traditionally the trust evaluation model is based on feedback mechanism, which only depends on transactions number neglecting transaction amount, etc. This may lead to the transaction risk in the new transaction. In this paper, a novel trust evaluation model is presented, which reflects recommender's trust value and transaction amounts when computing the trust value of peer. In addition, the model introduces the factor of transaction period while updating peer's trust value, which embodies that the feedback occurred in different period have different influence to peer's trust value. Therefore results of trust evaluation become more accurate, the novel trust evaluation model is effective against malicious behavior. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Advanced Dynamic Binary Interleaving Codes for UWB-OFDM WPAN Systems

    Publication Year: 2009 , Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (540 KB) |  | HTML iconHTML  

    This paper presents a novel binary interleaving process foreseen as a pseudo spreading technique against interference noise and selective channels. The system addresses time-variant binary block interleaving codes considered here for UWB-OFDM transmissions as an alternative to the ECMA-368 standard binary cyclic shifter stage. The interleaving technique denoted dynamic binary interleaving code (DBIC), is designed and assessed on ECMA-368 PHY layer and a optimized UWB-OFDM system based on spectrum efficiency optimization combined with advanced interleaving techniques. DBIC considers a recent interleaving technique denoted turbo-like interleaver (TLI) allowing multiple interleaving pattern generation into a flexible way. To achieve multi Gbps on the air interfaces, 16 QAM modulated sub-carriers are considered involving ECMA-368 interleaver adaptation. Interleaving benchmarking is performed upon these 2 systems operating in the 60 GHz RF band. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Allowing Short-Lived TCP Sessions to Ramp-UP in Broadband Wireless Networks

    Publication Year: 2009 , Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (159 KB) |  | HTML iconHTML  

    In this paper, we propose a dynamic OFDMA based subcarrier/power allocation which aims to protect the newly established TCP connections. The proposed allocation utilizes an estimation of the current congestion window of TCP connections to allocate resources so that vulnerable flows with small congestion windows avoid entering packet recovery via retransmission time out. In addition, for the long-lived TCP flows, the theoretical TCP throughput which can be accomplished in their end-to-end path is used as their desired achievable data rate on wireless link. Such a technique can be of significant importance since due to its popularity, TCP is commonly used over the broadband wireless networks. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An Integrated Framework for Vehicular and Urban Sensing

    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (505 KB) |  | HTML iconHTML  

    In this work, we examine the integration of vehicular sensing and urban sensing to assess the operation, performance and environmental impact of vehicles in urban settings. We have designed an integrated framework for vehicular and urban sensing. A prototype implementation of this framework has been developed by building a testbed based on campus shuttle buses. We discuss the design and implementation of this system, focusing on its hardware platform and software architecture. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An Overview of Ongoing Activities in the Field of Channel Modeling, Spectrum Allocation and Standardization for mm-Wave and THz Indoor Communications

    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (251 KB) |  | HTML iconHTML  

    This paper gives an overview of current issues in the field of mm-wave and THz communications. A concept for radio channel modeling is presented together with the latest channel investigation results in this frequency range. In addition we discuss the status quo of standardization activities and the worldwide ongoing spectrum allocation plans. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An Overview of Semiconductor Technologies and Circuits for Terahertz Communication Applications

    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (750 KB) |  | HTML iconHTML  

    An overview of the current status of the semiconductor device technologies and circuits for terahertz applications, especially for the broadband wireless communication systems, is provided in this work. Comparison between various semiconductor device technologies such as III-V HEMTs and HBTs, SiGe HBTs, and Si MOSFETs is presented and the current record performances of each technology are described. In addition, the best performing amplifiers, oscillators, and mixers as of today for possible terahertz communication system applications are presented and related issues are discussed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Application-Driven Cross-Layer Approaches to Video Transmission over Downlink OFDMA Networks

    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (464 KB) |  | HTML iconHTML  

    This paper investigates the problem of multiuser video transmission over downlink OFDMA networks. Two schemes, named quality-maximizing and quality-fair, are proposed and analyzed, which are to maximize the video quality without and with fairness constraint, respectively. The novelties of the schemes are characterized by the video application driven and the joint solution to the packet scheduling and subcarrier allocation. The algorithm is compatible with the future wireless networks, such as WiMAX and IMT-Advanced. The simulation results show that the proposed schemes outperform the conventional methods in terms of received video qualities and users' fairness. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Approaches for the migration of optical backbone networks towards Carrier Ethernet

    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (479 KB) |  | HTML iconHTML  

    This paper describes migration strategies in optical networks. It is expected that the conversion of current transport networks (IP/MPLS over SDH) into more packet oriented (IP/MPLS over Ethernet) technologies will result in significant cost savings for network operators. The state space of a migrating network can be modeled as a directed graph. To find the optimal migration path within this state oriented graph, several approaches, such as the incremental migration and the all-period migration can be used. Current research results regarding cost development and resource utilization in layer 1 and layer 3 are presented in this work. The effects of several planning techniques within such uncertain environment, like routing and grooming, on the total cost development are discussed, too. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Blind MC-DS-CDMA Parameters Estimation in Frequency Selective Channels

    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (193 KB) |  | HTML iconHTML  

    An apportunistic or cognitive radio system needs accurate knowledge of the radio spectrum it operates. The concept of cognitive radio is also exploited in the railway context in order to satisfy high availability and interoperability of wireless telecommunication systems everywhere as required by operational or safety applications deployed by the railway operator. It allows for example dynamic spectrum allocation versus QoS (Quality of service) or traffic requirements and very often spectrum reuse especially in rural areas. Blind multi-carrier transmission recognition methods based on the discrimination between single-carrier and multi-carrier modulations to estimate their parameters have been addressed in the literature. Some powerful techniques use autocorrelation and cyclic autocorrelation based features of the transmitted signal. In this paper, we propose a blind parameter estimation based on analysis of fluctuations of autocorrelation estimators which was initially employed in CDMA signals interception. The proposed technique leads to a fast efficient parameters estimation and is insensitive to receiver phase and frequency offsets as it is highlighted in simulation results. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Capacity Assignment for Multipath Routing in Multiclass Two-Tier Wireless Mesh Networks

    Publication Year: 2009 , Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (225 KB) |  | HTML iconHTML  

    Nowadays, Wireless Mesh Networks (WMN) are increasingly supporting jointly non real-time and real time applications that required a guaranteed bandwidth. A new methodology is presented throughout this study to show that an important aspect of dimensioning WMNs, considering mobility of users, fairness and their demand according to two types of running applications. This leads to satisfying voice demand while ensuring fairness among the non delay-sensitive applications. We propose the combination of both capacity estimation based on users mobility and multipath scheme. We compare our proposition with single path routing based on the shortest path criteria in terms of end-to-end throughput to show that it performs best. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Capacity of Wireless Ad-Hoc Broadcast Networks under Realistic Channel Models

    Publication Year: 2009 , Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (480 KB) |  | HTML iconHTML  

    In a wireless broadcasting scenario, some of the nodes can help the source node by forwarding the received information. Due to the interference from multiple transmissions, selection of these nodes directly affects the performance of the system under a given total power and hop constraint. In this paper, we first analytically find the number and the positions of the rebroadcasting nodes that achieve the optimal broadcast capacity under the continuum model. Following the results of this part, we propose two heuristics, one centralized and another distributed, for relay selection in practical scenarios. Then, we discuss the broadcast capacity performances of these algorithms under different system settings. The results illustrate that using a distributed relay selection method brings significant gains to the broadcast capacity under a realistic system model. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Challenges and Opportunities in the Design of TRILL: A Routed Layer 2 Technology

    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (205 KB) |  | HTML iconHTML  

    This paper describes some of the interesting technical issues that arose in the design of TRILL (TRansparent Interconnection of Lots of Links), a technology being standardized in IETF, that combines the ease of configuration usually associated with layer 2, with the flexibility, robustness, and route optimizations usually associated with layer 3. In addition to describing the issues, we describe the alternative proposals, and the rationale behind the resolutions. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Channel Sounding Pilot Overhead Reduction for TDD Multiuser MIMO Systems

    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (148 KB) |  | HTML iconHTML  

    Coordinated linear transmit-receive processing with beam selection is a method to utilize all degrees of freedom available in multiuser multiple-input multiple-output (MIMO) cellular systems in order to increase system capacity. By applying channel state information in the transmitter (CSIT), the base station (BS) is able to spatially multiplex downlink data streams for different users. In the time division duplex (TDD) mode, CSIT for the BS is provided by means of uplink CSI sounding pilots. However, antenna-specific uplink pilot streams cause an extensive overhead that restricts the size of the practical user group and the terminal antenna setup that can be handled within the same time-frequency slot. We propose to reduce the required overhead by letting the terminals form pilot beams by transmit precoding, based on the knowledge of the user-specific MIMO channels obtained via a downlink common pilot signal. The achievable rate of the system is evaluated in conjunction with channel estimation and linear receivers. According to the results, the performance loss induced by the incomplete sounding is minor, as the beamforming gain provided by multiple terminal antennas, and the multiuser diversity seen by the BS are retained. When taking into account the CSI estimation error in the BS, the overhead reduction turns out to improve robustness and even increase the average system capacity. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Coded Performance of OFDM and SC PHY of IEEE 802.15.3c for Different FEC Types

    Publication Year: 2009 , Page(s): 1 - 3
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (464 KB) |  | HTML iconHTML  

    In order to realize wireless gigabit transmission in one room, different 60 GHz systems are emerging. For the physical layer (PHY) orthogonal frequency division multiplexing (OFDM) as well as single carrier (SC) transmission are deployed. In this paper, the fundamental studies of coded performance of both approaches are extended by comparing different forward error correction (FEC) schemes for the final version of IEEE 802.15.3c in terms of bit error rate (BER) versus Eb/N0. Our results show that the SC PHY outperforms the OFDM PHY not only for high code rates but also for low code rates when using moderate low density parity check (LDPC) codes. Thus, very efficient, low cost 60 GHz devices can be designed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.