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Broadband Communications, 2000. Proceedings. 2000 International Zurich Seminar on

Date 15-17 Feb. 2000

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Displaying Results 1 - 25 of 49
  • 2000 International Zurich Seminar on Broadband Communications. Accessing, Transmission, Networking. Proceedings (Cat. No.00TH8475)

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  • MAP decoding of linear block codes based on a sectionalized trellis of the dual code

    Page(s): 271 - 278
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    Block codes for use in turbo coding schemes provide an alternative to punctured convolutional codes when high rate component codes are needed. Since block codes have large, time-varying trellis diagrams, full maximum a posteriori (MAP) soft-in soft-out decoders are very complex. It is shown how to modify the MAP algorithm to utilize a sectionalized trellis diagram of the dual code for decoding, which minimizes computational complexity for high rate component codes. This paper also gives simulation results for some high rate block turbo codes. View full abstract»

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  • Author index

    Page(s): 321
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    Freely Available from IEEE
  • On the global EMC aspect of broadband power line communications using the “HF” frequency band

    Page(s): 179 - 184
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    Measurement data and computer modelling is used to assess the potential of global cumulative radio interference effects caused by over the horizon ionospheric propagation of unwanted emissions from broadband power line communications (PLC) systems operating in the HF band (1-30 MHz). A comparison of the results with the ITU-R atmospheric radio noise atlas indicates that the present natural noise levels in electromagnetic quiet areas will not change significantly with a possible future large deployment of local access telecommunication systems using the low voltage electricity distribution networks if the maximum transmit power spectral density per PLC cell (user group sharing the same spectral resources) is below -40 dBm (Hz-1) View full abstract»

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  • Interworking between independent PROFIBUSes through ATM networks

    Page(s): 147 - 154
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    Field buses have been developed to fulfil real-time requirements of applications related to factory automation. However, they can only cover geographical areas such as factory halls or buildings which causes the occurrence of many small segments in larger environments unable to communicate among each other. In order to reduce this drawback a possible solution is to connect those field bus segments using interworking devices and a backbone network. A suitable backbone could be an ATM network. An interworking concept based on PROFIBUS/ATM bridges is presented in this paper. Simulations of an example PROFIBUS system were performed in order to study overall system behavior, to evaluate the feasibility of the presented concept and to show its limitations concerning the range of PROFIBUS applications it is suited for View full abstract»

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  • A distributed dynamic channel reservation framework for wireless ATM LANs

    Page(s): 119 - 125
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    A distributed method for dynamic channel reservation in wireless ATM is presented. The proposed method applies to wireless ATM LAN, where base stations act as hubs to offer wireless ATM access to mobile units. In the proposed method, base stations are competing to access and reserve time on separate frequencies. Competition disciplines are introduced, and their performance is evaluated and compared through simulations View full abstract»

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  • Transmit diversity using filtered feedback weights in the FDD/WCDMA system

    Page(s): 15 - 21
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    The transmit diversity concept adopted for the FDD mode of the third generation WCDMA system in 3G standardization has an open-loop and a closed-loop mode. The open-loop mode applies space-time block coding and is provides full diversity for two transmit antennas. The closed-loop mode has two submodes, which both utilize downlink channel measurements and feedback signaling in controlling the phase and/or gain transmit weights in the two transmit antennas. In this paper we review the open- and closed-loop concepts and propose an enhancement to the feedback modes to further improve their performance. The enhanced feedback modes allow the base station to filter the feedback weights received from the terminal to improve beam resolution and system robustness View full abstract»

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  • Frequency reuse and coding for GPRS multi-slot operation

    Page(s): 127 - 131
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    Due to the growing interest in mobile data applications, the Global System for Mobile communications (GSM) has been extended by the General Packet Radio Service (GPRS). It allows the transmission of packet data at moderate bit rates using random access channels within the existing GSM infrastructure. This paper analyses the impact of using multiple channels in a GSM system for GPRS packet transmission. Different combinations of frequency reuse and channel coding are evaluated for 1, 4 and 8 packet data channels (PDCH) per cell. A tight frequency reuse of 1, together with a strong error coding scheme was found to provide the highest capacity. The increased trunking efficiency for a system with 8 PDCH yields a capacity gain of about 64% over a system with only 1 channel. The results indicate that mixing circuit and packet switched traffic causes inefficient use of system resources. Since GSM voice services usually require a frequency reuse of 3 or 7, a separate overlaying network for GPRS provides better resource utilization and maximizes the number of users fulfilling the specified quality of service (QoS) requirements View full abstract»

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  • A new approach to automatic base station placement in mobile network

    Page(s): 301 - 306
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    The tremendous growth in the demand for mobile services has resulted in an explosion in base station (BS) density and network complexity, making the conventional manual planning processes highly inefficient. An innovative approach for automatic BS placement is presented in this paper. The powerful optimization strategy forms the core of the automatic process, which determines the number of BS, their locations and configurations to achieve a high-quality network View full abstract»

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  • Design issues for high performance active routers

    Page(s): 199 - 205
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    Active networking is a general approach to incorporating general-purpose computational capabilities within the communications infrastructure of data networks. This paper proposes the design of a scalable, high performance active router. This is used as a vehicle for studying the key design issues that must be resolved to allow active networking to become a mainstream technology View full abstract»

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  • Turbo equalisation: implementation and importance for communication systems

    Page(s): 23 - 30
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    This paper discusses a recent iterative equalisation technique called “turbo equalisation”. We specifically aim to develop a general model for a coded interleaved transmission system with a channel with memory. We show the general detection/decoding procedure before elaborating on a new alternative interference canceler-based method to reduce complexity. We use examples from DS/CDMA, and ISI channels to show performance under various situations View full abstract»

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  • 64-QAM OFDM with TCM coding and waveform shaping in a time-selective Rician fading channel

    Page(s): 257 - 261
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    In this paper, the simulation results of a 64-QAM OFDM system in a time-selective Rician fading channel are presented. First, results dealing with the improvement of OFDM system performance by waveform shaping and TCM coding in an AWGN channel are reported. Second, coded OFDM system performance in a time-selective Rician fading channel is investigated View full abstract»

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  • A robust switch architecture for bursty traffic

    Page(s): 207 - 214
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    A novel way of building switch system architectures, based on the combination of an output-buffered switch with input queues that sort arriving packets on a per-output-port basis, is proposed that has a scheduling complexity of O(N). Simulation results to demonstrate the high and robust performance achieved with the proposed system architecture are presented, and a practical implementation is outlined View full abstract»

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  • BER evaluation for optical signals with combined EDFA and interference noise

    Page(s): 85 - 87
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    We investigate the effects of combined interference noise and Gaussian noise on the BER evaluation. For the case of one interference source and additional Gaussian noise we propose a method to identify the interference noise and to evaluate the correct BER by the method of modified Chernoff bounds View full abstract»

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  • Algorithm design and system implementation for advanced wireless communication systems

    Page(s): 229 - 235
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    The next generation of mobile communication systems will offer vastly increased functionality while operating with multiple standards. In a first phase, multimodality and functionality will be predefined and fixed. In a second phase we will encounter increased adaptivity to optimally utilize the network View full abstract»

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  • A note on the fairness of TCP Vegas

    Page(s): 163 - 170
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    This paper shows that TCP Vegas' fairness critically requires an accurate estimation of propagation delay. We also show that, in practice, this may be difficult to achieve and we discuss how to choose the parameters α and β that control the window sizes' update View full abstract»

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  • An efficient multiple access technique for wireless ATM networks with QoS guarantees

    Page(s): 293 - 299
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    The basic concepts of the MAC (medium access control) protocol and the underlying traffic scheduling algorithm developed within the ACTS (Advanced Communications Technologies and Services) project Magic WAND (Wireless ATM Network Demonstrator) are outlined. A novel multiple access technique for the radio interface of WAND is proposed. Simulation results, showing that the proposed technique significantly improves system performance, are also presented View full abstract»

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  • Performance improvement in DS-spread spectrum CDMA systems using a pre- and a post-RAKE

    Page(s): 39 - 46
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    Mobile communications systems based on code division multiple access (CDMA) and direct sequence spread spectrum techniques have been gaining a lot of ground lately. The RAKE receiver is a well known technique in spread spectrum systems, which is used to obtain signal diversity in multipath environments. In TDD systems, a technique known as pre-RAKE has been proposed recently, in which the signal processing is transferred to the transmitter, and it has been shown that this technique provides a capacity increase in the downlink. In this paper we propose a combination of both methods and show that a substantial performance improvement can be reached this way View full abstract»

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  • Biorthogonal multicode modulation for high-rate high-reliability personal communications requiring controlled peak-to-average transmit power ratio

    Page(s): 263 - 270
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    A modulation scheme is proposed for high-information-rate high-reliability personal communications where controlled peak-to-average transmit power ratio is an issue. The scheme is a hybrid of classical biorthogonal modulation and code division multiple access multicode modulation. Analytical and simulation results are presented for static AWGN channels and simulation results are presented for flat fading channels View full abstract»

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  • Performance analysis of an adaptive OFDM packet data system

    Page(s): 237 - 243
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    This paper studies the performance of a broadband OFDM system concept intended for fixed and nomadic applications. The system is designed for efficient packet data transmission, and in particular for TCP/IP. A combination of OFDM, adjustable time division duplexing (TDD), adaptive modulation/coding, and selective ARQ is used to provide a flexible and robust air interface. Estimates of the achievable data rates and spectral efficiencies under different deployment scenarios are obtained from a combination of link-level and system-level simulations View full abstract»

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  • Aperiodic properties of generalized binary Rudin-Shapiro sequences and some recent results on sequences with a quadratic phase function

    Page(s): 279 - 286
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    This paper addresses the problem of designing good spreading sequences for CDMA systems that have small-valued auto- and cross-correlation functions. In contrast to the usual mini-max criteria, the l2 criteria of goodness are used to assess correlation properties of spreading sequences. To motivate it, direct evidence is given to demonstrate the utility of the l2 criteria in the context of CDMA performance. Following, these criteria are applied to two types of known unit-magnitude sequences: generalized binary Rudin-Shapiro sequences, and sequences with quadratic phase function. The construction rule of the well-known binary Rudin-Shapiro sequences is based on a recursion formula that starts with the Kronecker sequences. It is shown that the asymptotic limits (N→∞) of l 2 criteria obtained for original Rudin-Shapiro sequences are also valid in case of two arbitrary sequences obtained by means of the same recursion formula as long as the initial sequences are complementary. As to the sequences with quadratic phase function, the upper and lower bounds on the inverse merit-factor are proved to decrease with the order √N+1, which indicates excellent auto-correlation properties of the sequence View full abstract»

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  • Calculation of error probability of CDMA communication systems using saddlepoint method

    Page(s): 63 - 68
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    An efficient method for evaluating the average error probability of direct sequence spread-spectrum code-division multiple-access (CDMA) communication systems is presented. Various phase-shift keying systems are analyzed. Results of Gaussian approximation, saddlepoint approximation, and numerical contour integration by the saddlepoint method are compared. The variance and the error probability can be computed from the moment generating function of the receiver output. General and simple formulas for evaluating the multiple access interference variance are presented for systems using deterministic or random signature sequences. Both quadriphase-shift keying (QPSK) and offset quadriphase-shift keying (OQPSK) systems yield the same performance when the signal-to-noise ratio criterion is adopted. However, accurate numerical computations show that they do not have the same one. The results show that MSK yields better performance than QPSK and OQPSK View full abstract»

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  • On the quality provisioning for video in ATM networks

    Page(s): 139 - 145
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    This paper is an assessment of video communication over ATM networks covering bit rate regulation, traffic characterization and multiplexing modes. The purpose of the paper is to amalgamate results from the literature to determine how video should be serviced in ATM. One finding is that the statistical bitrate service may not be as suitable a network service for video as hoped View full abstract»

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  • Protocols for a portable multimedia interactive satellite communication system

    Page(s): 111 - 117
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    This paper proposes lower layer protocols for a portable multimedia satellite communication system using a bi-directional satellite circuit. The point-to-point protocol is extended for controlling forward satellite channels based on a reservation scheme. Simulation results show that this control scheme enlarges the number of simultaneous accessing users and enhances TCP throughput View full abstract»

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  • The effects of fibre amplifier phase noise on radio over fibre signals

    Page(s): 89 - 91
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    We report on an experimental investigation of the effects of EDFA spontaneous emission on the phase noise of microwave and millimetre-wave modulated optical signals View full abstract»

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