bluuebunny/crossref_metadata_2025_split huggingface dataset:
Array Codes Correcting Likely Burst Error Patterns
Authors: Breitbach Markus , Bossert Martin , Zyablov V. , Sidorenko V. 
Published: September 2008

AbstractThis contribution considers data transmission over channels which are corrupted by two‐dimensional bursts of errors. A code is constructed that allows to correct one rectangular burst. Its code rate is close to the generalized Singleton bound, and in the case of binary code symbols it can be implemented efficiently using only shift registers and XOR gates. Based on this code, constructions of codes are studied whose error correcting capabilities are restricted to a subset of rectangular bursts. When only likely error patterns can be corrected, the code rate can be raised while accepting only a small increase in error probability. In particular it will be shown that asymptotically these codes permit data transmission with arbitrarily low error probability at a rate beyond the Generalized Singleton bound.
Modeling of a Cost‐to‐Benefit Frequency Function for the Design of Wideband Wireless LANs
Authors: Ruggieri Marina 
Published: September 2008

AbstractIn the deployment of Wireless Local Area Networks for Wideband communications (WWLAN), a key and particularly critical role is played by the choice of the operation frequency range. In fact, different and conflicting aspects must be taken into account in order to perform an effective selection. In this perspective, the paper proposes a model of the various features which contribute to the selection of the frequency range in a WWLAN, through the introduction of a cost‐to‐benefit frequency function. The model, whose role in the design of WWLANs is also described in the paper, is adopted to explore several situations varying the model parameters. The frequency behavior of the modeled function is investigated, in order to select the optimal WWLAN operation frequencies in the range 10+60 GHz. The achieved results, which are reported and commented in the paper, indicate the 60 GHz range as a very attractive candidate for the design and development of future WWLANs.
Efficient Connection Admission Control Algorithms for Adaptive QoS Real‐Time Connections over ATM Networks
Authors: Jia Weijia , Zhao Wei 
Published: September 2008

AbstractIn this paper, we extend the traditional QoS model into one that is adaptive. We address how to admit real‐time connections under this new model. We investigate various search techniques in connection admission and assess their tradeoffs under different performance criteria. We show that our connection admission control algorithm with heuristic search techniques can increase the probability that a connection is admitted, and provide the best possible QoS to admitted connections while at the same time maintaining the execution time of the algorithm at a reasonable level. Many existing CAC algorithms for real‐time connections use direct testing techniques to determine if deadlines constraints can be satisfied. This is usually time consuming due to the extensive computation involved in obtaining delay bounds. We introduce an indirect testing method that can substantially reduce the execution time of CAC algorithms.
Accelerated Signalling for the Internet over ATM (ASIA)
Authors: Boyer Jacqueline , Boyer Pierre , Dugeon Olivier , Guillemin Fabrice , Mangin Christophe 
Published: September 2008

AbstractTo face up the rapid development of Internet services with even more growing needs in terms of quality of service and bandwidth, we introduce in this paper an accelerated signalling capability for the ATM network. As a preliminary, we draw attention to the fact that cell spacing can regulate the dynamics of TCP over ATM if the spacing period is adequately chosen. Then, we propose to associate with each Internet information flow (generated by TCP or UDP) a Deterministic Bit Rate (DBR) virtual channel connection within the ATM network. The cell spacing mechanism actually makes the cell stream of an Internet information flow compliant with a DBR connection, for which quality of service objectives in terms of negligible cell loss and bounded cell transfer delays can be guaranteed. To achieve this, we study a synchronization method between the two connection establishment procedures, namely that at the Internet protocol level and the signalling procedure for the ATM network. The ATM connection is established throughout the network via a light‐weight signalling procedure, which relies on the exchange of single cell messages consisting of Resource Management (RM) cells. The addressing system proposed for this accelerated signalling capability is that of classical IP, which is and will certainly be the predominant one in the near future.
Performance of a TCP/IP Backbone Based on Optical Packet Switching
Authors: Callegati Franco , Casoni Maurizio , Raffaelli Carla , Bostica Bruno , Burzio Marco , Masip‐Torné Jaume , Solé‐Pareta Josep 
Published: September 2008

AbstractThe application of the Optical Transparent Packet (OTP) network concept, as developed in the framework of the ACTS KEOPS project, in the evolving Information and Communication Network Technology is presented where users are IP traffic sources. In particular the OTP network is supposed to operate as an interconnection facility for high capacity backbone routers and to provide the high switching capability needed for border routers at Network Access Points. The network architecture is described and performance evaluation is carried on at network access and on end‐to‐end basis. The investigation of algorithms for managing packet flows with different quality of service requirements is also developed as a key issue for the future network scenarios.
A Framework for Dynamic Protocol Configuration
Authors: Plagemann Thomas 
Published: September 2008

AbstractTraditional end‐system protocols are not able to support the wide range of Quality of Service (QoS) requirements of existing and emerging distributed multimedia applications on top of current networks. The aim of protocol configuration in Da CaPo (Dynamic Configuration of Protocols) is to combine fine granular software and hardware building blocks at runtime in such a manner that the resulting protocol configuration fulfills the application requirements and needs as less resources as possible. Main features of Da CaPo include a formal model, a new approach for specifying application requirements as objective functions, and a unified module interface that allows syntactically unconstrained configuration of software and hardware building blocks. The performance evaluation of the prototype implementation demonstrates that the overhead introduced by the flexible approach is marginal compared to modules that access multiple bytes in each packet. Thus, decreasing protocol complexity by configuring appropriate protocols distinctly increases protocol performance. Furthermore, the flexible approach is able to support the broad range of QoS requirements and is open for future developments.
Multicast Congestion Control for Active Network Services
Authors: Azcorra Arturo , Moreno Jose Ignacio , Calderón María , Sedano Marifeli 
Published: September 2008

AbstractThe growing interest in multicast applications for the Internet, that will increase with the introduction of active network technoiogy, brings out the need for providing effective congestion control mechanisms. This paper studies the problems and specific requirements for multicast congestion control. From this study, a general mechanism is proposed and its advantages and compliance with the requirements are described. The general mechanism is then applied in detail to the Reliable Multicast Active Network Protocol implementation. We conclude that active networks provide good support for congestion control mechanism and that the proposed approach satisfies the stated requirements. However, further work is needed to optimize the values of the system parameters.
Spread Spectrum‐Based Subcarrier Recovery Method for Multi‐Carrier Code Division Multiplexing System
Authors: Hara Shinsuke , Budsabathon Montree 
Published: September 2008

AbstractA time domain Spread Spectrum (SS)‐based subcarrier recovery method is proposed for down‐link Multi‐Carrier Code Division Multiplexing (MC‐CDM) system, which periodically inserts SS pilot signals into data signal stream in a time division manner at the transmitter. Instantaneous channel impulse response is first estimated by correlating the received pilot signal at the receiver, and then corresponding instantaneous frequency response essential for subcarrier recovery is calculated from the Discrete Fourier Transform (DFT) of the estimated impulse response. The SS pilot‐assisted method is also applicable to Direct Sequence (DS)‐CDM system as a means to estimate instantaneous channel impulse response for Rake combining, and taking the same approach in both MC‐CDM and DS‐CDM systems, there is no large difference between them in terms of transmission efficiency and receiver complexity. The proposed MC‐CDM system must be a promising down‐link multiplexing protocol, because it can achieve better bit error rate (BER) performance than the DS‐CDM system with the same SS pilot‐assisted Rake combiner in frequency selective fast Rayleigh fading channel.
Performance Effects of the Uplink Asynchronism in a Spread Spectrum Multi‐Carrier Multiple Access System
Authors: Kaiser Stefan , Krzymien Witold A. 
Published: September 2008

AbstractIn this paper we investigate the effects of the asynchronism of user signals in the uplink of a spread spectrum multi‐carrier multiple access (SS‐MC‐MA) system. Different propagation delays due to different distances between the mobile transmitters and their base station cause asynchronous arrivals of the uplink signals in addition to multipath propagation. The proposed uplink SS‐MC‐MA scheme uses for synchronization only the frame structure received on the synchronous downlink and requires no additional synchronization measures. A guard interval that is smaller than the sum of the maximum time offset between the users and the maximum excess delay of the frequency selective multipath channel is used. It minimizes the loss in bandwidth efficiency by allowing residual interference. The residual interference is minimized by proper positioning of the detection interval in the receiver. It is shown that with this approach the guard interval can be reduced by about 50%. The performance of the proposed uplink scheme is compared to an uplink SS‐MC‐MA scheme with perfect synchronization.
A Fractionally Spaced Decision Feedback Joint Detection Proposal for Multi Carrier CDMA
Authors: Ikonomou Demosthenes , Vandendorpe Luc 
Published: September 2008

AbstractSignificant attention has been paid lately on Multiple Access (MA) schemes based on Code Division Multiple Access (CDMA) as well as Orthogonal Frequency Division Multiplexing (OFDM), especially in the context of the UMTS Terrestrial Radio Access (UTRA) selection process. The advantages and weaknesses of CDMA schemes are relatively well known as they provide high immunity against multipath, high flexibility and they are well suited for variable rate links. On the other hand, their performance and capacity is strongly dependent and limited by Multiple Access‐ and Self‐ Interference (MAI and SI respectively). The advances in DSP technology resulting in compact and relatively easy to implement digital modulators combined with the favourable characteristics of OFDM such as immunity to Inter Symbol Interference (ISI), bandwidth efficiency and frequency diversity have resulted over the last years in a number of different radio access scheme proposals for mobile channels that combine OFDM and CDMA. In the context of this paper, we focus in the system implementation known as Multi Carrier CDMA (MC‐CDMA). The use of equalising receiver structures versus the use of the Guard Time technique in MC transmission schemes is discussed and a Fractionally Spaced Decision Feedback Equaliser (FS/DFE) receiver structure for an MC‐CDMA system is proposed. Its performance is evaluated by means of computer simulations and compared to the use of the Guard Time technique. A FS Multiple Input Multiple Output (MIMO) DF equalising structure performing Joint Detection (JD) further improves the performance of the proposed equalising scheme in terms of MAI.
A Promising New Wideband Multiple‐Access Scheme for Future Mobile Communications Systems
Authors: Schnell Michael , De Broeck Isabella , Sorger Uli 
Published: September 2008

AbstractRecently, “Interleaved Frequency‐Division Multiple‐Access” (IFDMA) has been introduced as a new spread‐spectrum multiple‐access scheme for mobile communications which is suitable for both downlink and uplink applications. IFDMA combines spread‐spectrum multicarrier transmission with frequency‐division multiple‐access and, therefore, is capable of achieving frequency diversity while multiple‐access interference is avoided. Moreover, compared to other wideband multiple‐access schemes IFDMA shows several additional advantages. The cost to achieve these advantages is to allow for intersymbol interference. However, the effects of intersymbol interference can be reduced significantly by applying an equalizer at the IFDMA receiver.In this paper, the principle of IFDMA is reviewed and it is shown that IFDMA is a promising new wideband multiple‐access scheme suitable for future mobile communications systems. The frequency diversity achievable with IFDMA is determined as well as performance results for uncoded and coded transmission taking into account different equalization techniques. As a result, uncoded IFDMA applying optimum equalization performs even better than uncoded multicarrier code‐division multiple‐access applying maximum‐likelihood multi‐user detection. In the case of coded IFDMA transmission coding gains up to 6.8 dB at a bit‐error‐rate of 10−‐4are achieved using a standard convolutional code. An additional performance gain of up to 2.2 dB is possible if equalization and decoding are considered jointly.
The Sensitivity of MC‐CDMA to Synchronisation Errors
Authors: Steendam Heidi , Moeneclaey Marc 
Published: September 2008

AbstractIn this contribution, we investigate the sensitivity of MC‐CDMA systems to synchronisation errors. We show that the signal‐to‐noise ratio (SNR) of the MC‐CDMA system at the input of the decision device in the presence of a carrier frequency offset or a clock frequency offset is a rapidly decreasing function of the number of carriers. For a maximal load, carrier phase jitter and timing jitter give rise to a degradation that is independent of the spectral content of the jitter; moreover, the degradation caused by carrier phase jitter is independent of the number of carriers. A constant carrier phase offset and a constant timing offset cause no degradation of the MC‐CDMA system performance.
Pseudo‐Noise Code Synchronization of Multicarrier DS‐CDMA Systems on Multipath Fading Channels Part I: Analysis of the Serial Search Multiple‐Dwell Acquisition
Authors: Sheen Wern‐Ho , Chang Ming‐Jou , Wang Huan‐Chün , Wu Cheng‐Shong 
Published: September 2008

AbstractPseudo‐Noise (PN) code synchronization is investigated in this and an accompanied paper for multicarrier direct‐sequence code division multiple access (DS‐CDMA) systems on multipath Rayleigh fading channels. In this part, a new analysis is developed to evaluate accurately the mean acquisition time performance of serial search multiple‐dwell acquisition systems. The method is unique in that it can take the correlations due to fading into account, including the correlations among different dwells and carriers. In addition, the effects of system parameters on the acquisition performance such as carrier and user numbers, fading correlations, dwell number and times, and thresholds can be easily evaluated, as compared to computer simulations, and, therefore, facilitating the design of the acquisition subsystem. Our analytical results are verified by computer simulations.
A Multimode and Variable‐Rate Voice Communications System with Source‐Matched Error Protection for Mobile Communications
Authors: Babich Fulvio , Vatta Francesca 
Published: September 2008

AbstractThis paper presents a performance evaluation of the multimode Fast Variable Rate CELP coder developed by CSELT S.p.A. in the UMTS Code Division Testbed (CODIT) Project [1] for applications involving channels with time‐varying error characteristics. The radio channel is statistically modelled by one Rician or Rayleigh‐distributed desired signal and several uncorrelated Rayleigh plus log‐normally shadowed interfering signals, propagating according to two different laws: a dual path loss law with a turning point (microcellular environment) and a single path loss law (macrocellular environment). For channels with these error characteristics, each mode of the Fast Variable Rate CELP coder has a particular allocation of bits between source and channel coding stages, leading to an unequal error protection code tailored to suit the different error sensitivities of the source bits. It is shown that, on the basis of the sensitivity evaluation of source bits to errors, according to two different error sensitivity measures. Forward Error Correction whose power is matched to the error sensitivity of the source bits can be used. Increased robustness of source bits to errors can thus be obtained while satisfying bandwidth requirements.
Routing and Wavelength Assignment in Optical Networks Using Genetic Algorithms
Authors: Beckmann Dirk , Killat Ulrich 
Published: September 2008

AbstractIn this paper we consider the wavelength requirement for all‐optical networks based on wavelength‐division multiplexing (WDM). Given a static channel demand, the problem of routing and wavelength assignment (RWA) in such networks has to be solved. Due to the restricted number of wavelengths available on each link it is desirable to get a solution of the RWA problem, in which the needed number of wavelengths is minimized. Unfortunately, this optimization problem belongs to the class of NP‐complete problems. Therefore in this paper we present a new powerful method for the approximative solution of the RWA problem. This new approach is based on the combination of a genetic algorithm and a quite simple heuristic. The efficiency of this combined algorithm is demonstrated by the application to some well known benchmark problems.
Capacity of Multi‐antenna Gaussian Channels
Authors: Telatar Emre 
Published: September 2008

AbstractWe investigate the use of multiple transmitting and/or receiving antennas for single user communications over the additive Gaussian channel with and without fading. We derive formulas for the capacities and error exponents of such channels, and describe computational procedures to evaluate such formulas. We show that the potential gains of such multi‐antenna systems over single‐antenna systems is rather large under independenceassumptions for the fades and noises at different receiving antennas.
A Radio Independent Network – the Enabler for Software Radio
Authors: Berruto Ermanno , Diaz Pilar , Fleming Gary 
Published: September 2008

AbstractSoftware radio will likely have a significant role to play in third generation mobile systems. The first tentative steps towards identifying the impact of software radio on a mobile network have already been taken in the RAINBOW project. This paper will consider network issues related to the software radio concept. The requirements on the network to allow the use of software radio in future generation mobile systems will be presented. Significant attention will be given to the network design required to allow software radio to be exploited to its full potential.
Decoding and Equalization with Analog Non‐linear Networks
Authors: Hagenauer Joachim , Offer Elke , Méasson Cyril , Mörz Matthias 
Published: September 2008

AbstractUsing analog, non‐linear and highly parallel networks, we attempt to perform decoding of block and convolutional codes, equalization of certain frequency‐selective channels, decoding of multi‐level coded modulation and reconstruction of coded PCM signals. This is in contrast to common practice where these tasks are performed by sequentially operating processors. Our advantage is that we operate fully on soft values for input and output, similar to what is done in 'turbo' decoding. However, we do not have explicit iterations because the networks float freely in continuous time. The decoder has almost no latency in time because we are only restricted by the time constants from the parasitic RC values of integrated circuits. Simulation results for several simple examples are shown which, in some cases, achieve the performance of a conventional MAP detector. For more complicated codes we indicate promising solutions with more complex analog networks based on the simple ones. Furthermore, we discuss the principles of the analog VLSI implementation of these networks.
Letter Four “Firsts” in Telephony
Authors: Catania Basilio 
Published: September 2008

AbstractAt the beginning of telephony, it soon became evident that telephone lines required better conductors, with larger cross‐section, with respect to telegraph lines, as well as measures to counteract the skin effect. Moreover, inductive loading allowed doubling the range of the line. Call signaling systems, anti‐sidetone circuits and measures to insure the quietness of the environment must also be devised. This letter reminds the pioneering work of Antonio Meucci in all these areas.
A Distributed Control Protocol for Wavelength Routing with Fairness Improvement in WDM Networks
Authors: Mohan Curusamy , Murthy Chebiyyam Siva Ram 
Published: September 2008

AbstractThis paper considers the problem of distributed routing with fairness improvement in wavelength‐routed wavelength‐division multiplexed (WDM) networks with dynamic traffic conditions. The wavelength continuity constraint imposed by WDM networks causes increased blocking of connection requests. The performance loss is more for connections with longer hop counts, when compared to that for connections with shorter hop counts. This is further worsened when distributed routing is used due to the reservation conflicts. We propose a distributed control protocol to select a usable wavelength and route and to improve fairness among connections with different hop counts. The proposed dynamic priority based fairness improvement scheme(DPFS) improves fairness among connections by enforcing dynamically varying priority based control to the connection requests over access to a subset of the available wavelengths. while allowing a free access to the remaining wavelengths. We study the effectiveness of the proposed protocol through extensive simulation experiments. The results show that the proposed scheme improves fairness significantly with an acceptable level of degradation in the overall network performance.