bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Support of Bandwidth on Demand Service over Wide‐Area WDM Optical Networks
Authors: Nen‐Fu Huang , Yao‐Tzung Wang , Bo Li , Te‐Lung Liu 
Published: September 2008

AbstractFuture broadband networks must support integrated services and offer flexible bandwidth usage. Most existing proposals for wide‐area wavelength division multiplexed (WDM) networks employ circuit switching adopting the concept of lightpath, in which each circuit or lightpath occupies an entire wavelength. This, however, is not suited for end‐to‐end transport of information streams, typically with each stream having its unique traffic characteristics such as the bandwidth needed, different traffic bursty nature, and diverse service requirements. In this paper, we explore the extensions of the functions of what we refer as the optical link control (OLC) layer, native on top of optical layer, to offer finer granularity of wavelength usage and further enable the possibility of bandwidth on‐demand (BOD) service directly over WDM networks. The objective is to facilitate the support of integrated services over WDM networks and to mitigate the changes needed in the upper layers as well. The proposed approach attempts to exploit the strengths of both optics and electronics, in which packets are either routed end‐to‐end over a lightpath transparently, or forwarded from wavelength to wavelength by electronic switching, whenever required. Furthermore, in order to establish an end‐to‐end BOD connection, the issue of how to select the best wavelength to mute the given connection is also investigated. The effectiveness of the proposal is evaluated by simulation.
Transmitter Vs. Receiver SDL Solutions for Contention Resolution in WDM Ring Networks
Authors: Chlamtac Imrich , Fumacalli Andrea , Wing Eric , Wong Ming 
Published: September 2008

AbstractIn a single channel ring network the maximum achievable node throughput is inversely proportional to the number of nodes. Recent progress in WDM has opened the possibility to overcome this limitation by utilizing the multiple channels for parallel transmissions. Here we present an approach to obtaining a Concurrently accessed multi‐Ring all‐Optical WDM Network (CROWN) in which in‐transit packets pass through the node (are switched) without being convened into the electronic domain. This avoids the well‐known electronic bottleneck which further reduces the throughput of conventional WDM networks. The proposed architecture is also economical by using only a single high speed transmittcr and receiver per node. To allow data to be maintained in the optical format and still benefit from the multiplicity of channcls this low‐cost node configuration introduces the use of Switched Dclay Lines (SDL) as part of either the receiver or the transmitter hardware. It is shown that in the WDM multi‐channel system the (per node) capacity is at least 50% of the capacity of a single channel optical system with equivalent total bandwidth. However, the cost of the proposcd WDM solution is greatly reduced as it does not require that nodes access the network at the network aggregate bandwidth rate.
Simple On‐Line Scheduling Algorithms for All‐Optical Broadcast‐and‐Select Networks
Authors: Marsan Marco Ajmone , Bianco Andrea , Leonardi Emilio , Neri Fabio , Nucci Antonio 
Published: September 2008

AbstractThis paper considers all‐optical broadcast networks providing a number of slotted WDM channels for packet communications. Each network user is equipped with one tunable transmitter and one fixed receiver, so that full connectivity can be achieved by tuning transmitters to the different wavelengths. Tuning times are not negligible with respect to the slot time. A centralized network controller allocates slots in a TDWDM frame according to (long‐term) bandwidth requests issued by users. Simple on‐line transparent scheduling strategies are proposed, which accommodate bandwidth requests when they are received (on‐line approach), with the constraint of not affecting existing allocations when a new request is served (transparency). Strategies that attempt to allocate in contiguous slots all the transmissions of each source on one wavelength reduce overheads, are simple, and provide good performance. Even better performance can be achieved, at the cost of a modest complexity increase, when the transparency constraint is not strictly imposed, i.e., when a full re‐allocation of existing connections is performed once in a while.
New Optical Amplifier Placement Schemes for Broadcast Networks
Authors: Iness Jason , Mukherjee Biswanath 
Published: September 2008

AbstractWDM optical broadcast networks (based on the passive‐star coupler) may encounter large splitting and attenuation losses that need to be compensated for using optical amplifiers, such as EDFAs. However, optical amplifiers are costly, so their total count in the network should be minimized. This study will examine three different such amplifier‐placement schemes. The first approach utilize fewer amplifiers than previous schemes that do not add special hardware to avoid the near‐far effect. The second study considers a bidirectionai‐link network and it can use fewer amplifiers than a comparable unidirectional‐link network. The third study minimizes the number of amplifiers when the amplifiers are equipped with special hardware to avoid the near‐far effect, i.e., amplifiers are equipped with attenuators/filters to equalize amplifier input power on different wavelengths.
Performance Evaluation of the KEOPS Wavelength Routing Optical Packet Switch
Authors: Cadro Philippe , Gravey Annie , Guillemot Christian , Marie Raymond 
Published: September 2008

AbstractThis paper presents results concerning the performance evaluation of the KEOPS wavelength routing optical transparent packetswitch. This switch solves contention using optical delay lines; these delay lines are grouped in several sets, in the first stage of the switch. Each input port has access to a few of these delay lines, and each set of delay lines has access to each output port. Non‐FIFO output buffers are thus emulated using scheduling on a small number of delay lines with non‐consecutive delays. Under simplifying assumptions, analytical models are derived, and checked by simulation. These models provide efficient bounds for estimating packet loss probability, under the assumption of regular, balanced input traffic. It is shown that the proposed switch architecture achieves a good performance in terms of packet loss, with a number of delay lines significantly smaller than the ones currently used in other architectures.
Generalized Concatenation of Encoded CPFSK Modulation
Authors: Hautle Armin , Bossert Martin , Shavgulidze Sergo , Ugrelidze Nodar 
Published: September 2008

AbstractUsing the principles of generalized concatenation we introduce a new design for coded M‐ary CPFSK systems with modulation indexh= l/M. This technique is based on a set partitioning method of inner CPFSK into nested subsystems with increasing free Euclidean distance which are combined with several outer convolutional codes having different error‐correcting capabilities. In other words, we construct multilevel codes on the basis of inner modulationwith memory, namely CPFSK. The new generalized concatenated constructions were simulated in an additive white Gaussian noise channel. The multistep decoding algoritm is described where for soft output decoding the well‐known symbol‐by‐symbol maximum aposterioriprobability (MAP) algorithm is applied to the inner CPFSK. A comparison of the generalized concatenated codes with the best known trellis‐coded CPFSK schemes is also presented.
Signal Dependence of Cross‐Phase Modulation in WDM Systems
Authors: Rapp Lutz 
Published: September 2008

AbstractIn intensity modulated direct detection wavelength division multiplexing (WDM) systems, the effect of cross‐phase modulation (XPM) combined with groupvelocity dispersion causes signal distortion, which depends on the transmitted signals. The influence of the mutual dependence of these signals on the resulting degradation of the system performance is investigated theoretically and by means of simulations. Considering the propagation of two digital signals, the eye‐closure penalty is determined for different bit patterns and consequences for system design are pointed out. An approximation method is described in order to provide a better understanding of the signal dependence of XPM. Finally, a technique reducing the impact of XPM on data transmission in WDM systems is proposed.
Letter: Further Results on the Computation of the Outage Probability in Mobile Radio Systems
Authors: Tomba Luciano 
Published: September 2008

AbstractIn this letter we present a general method for the computation of the outage probability in fading radio channels. It is based on the joint use of the saddle‐point approximation and the gaussian quadrature rules. From our numerical results we have found that this procedure is fast and accurate at the same time.
Performance Analysis of a Call Admission Control Strategy for Adaptive‐Rate Traffic in Wireless Networks
Authors: Lombardo Alfio , Palazzo Sergio , Schembra Giovanni 
Published: September 2008

AbstractIn the near future, the telecommunication services provided by wireless networks will be characterized by high throughput and flexibility. Today the challenge in this area is to find techniques which will make it possible to introduce multimedia capabilities into mobile communications. The application of a wireless network structure made up of pico‐cells to solve this problem will cause an increase in the handover rate. Therefore, a major requirement in a wireless environment is to design an effective call admission control (CAC) strategy to minimize the handover drop probability. Another important requirement is to maximize network utilization, in terms OF the average number of channels used. The target of the paper is to define an extension of the Guard Channel CAC strategy for adaptive‐rate traffic sources, in such a way that both the handover drop probability and network utilization are optimized. In order to assess the effectiveness of the proposed CAC strategy, two Markov models of the system are introduced: one, from the network point of view, to evaluate global system performance, and another, from the user point of view, to evaluate the performance each user is provided with by the network. Numerical examples conclude the paper to analyze which factors most affect performance when the traffic bit rate is adaptive and the proposed admission strategy is applied.
An Integrated Multiple Access and Hierarchical Coding Scheme for Video Communication on Wireless Networks
Authors: Bolla Raffaele , Iscra Alessandro , Marchese Mario , Nobile Carlo , Tore Sandro Zappa 
Published: September 2008

AbstractA Medium Access Control (MAC) protocol of the Reservation Random Access (RRA) family is integrated with a hierarchical video‐coding scheme, to realize effective real‐time video services over the up‐link of a mobile wireless network. For every picture or for each group of contiguous pictures (GOP), the encoder generates an information set organized in a hierarchical layered structure. The base layer contains the information needed to a low quality video; the other layers contain data, which, if received and decoded, can enhance the video quality. The basic idea is to reserve bandwidth only to grant the transmission of base layer information, and modify the MAC scheme to manage the video enhancement data together with voice/dota streams. by adaptively transmitting the increimental video information only it the performances of other traffic classes will not drop below a certain threshold. The aim or this proposal is the improvement of the video stream quality in low load conditions, without a significant reduction of other traffic classes performance during high load periods. Several simulation results show the effectiveness of the proposed method.
Controlling QoS by Integrated Power Control and Link Adaptation in Broadband Wireless Networks
Authors: Leung Kin K. , Wang Li‐Chun 
Published: September 2008

AbstractWe propose and analyze the performance of an algorithm for integrated power control and adaptive, modulationkoding to achieve a specitied range of packct error rate for real‐time applications in broadband wireless packet‐switched networks. The algorithm applies the Kalman‐filter method [I] for power control, and adapts packet transmission to an appropriate modulation level, according to the packet error requirement, and the radio and interference conditions. A new criterion for maintaining stable transmission power is derived. Based on the criterion, the proposed technique performs the link adaptation and adjusts transmission power to achieve the specified packet error rate. The effectiveness of the proposed method is dcmonstratcd by several numcrical examples.
The Impact of Handover Protocols on the Performance of ABR Flow‐Control Algorithms in a Wireless ATM Network
Authors: Savoris Michael , Wolisz Adam , Krieger Udo R. 
Published: September 2008

AbstractConsidering the high‐speed data transfer by the ABR service class in a wireless ATM network, we investigate the impact of forward and backward hard handover protocols on the performance of the three rate‐based ABR flow‐control schemes Explicit Rate Indication for Congestion Avoidance (ERICA+), Fuzzy Explicit Rate Marking (FERM) and a new promising adaptation of FERM, called FERMA. We evaluatc the performance of these flow‐control protocols by means of an object‐oriented simulation modcl of a basic client‐scrvcr architecture. Considering a standard hard handover protocol in a wircless ATM nctwork. wc show that our proposcd enhanced signaling schemes based on a congestion‐awarencssconceptand their integratibn into thc ABR flow control have a positive influence on the stability and efficiency of the cell transfer by ABR connections. Morcovcr, we point out that the new adaptation of the fuzzy‐control scheme FERM provides a promising altcrnativc lo the ERICA+ algorithm.
On the Use of Sampling Theory for Passively Monitoring QoS in Packet Networks Fed by Different Types of Traffic
Authors: Cozzani Irene , Giordano Stefano 
Published: September 2008

AbstractPerformance measurements are a hot research topic for the design and control of high speed heterogeneous networks, such as the BISDN as well as the Internet. Our research in this field is concemed with a novel measurement system, with real‐time monitoring capabilities, whose working is based on sampling survey. The scenario used to test the accuracy of the proposed methodology is a “Passive QoS 2‐point measurement system” acting on an ATM network, which is fed with different kinds of traffic: synthetic traces (traditional as well as LRD models) and a trace of real ATM traffic captured on a transatlantic UK‐US link. Delay and loss characteristics, evaluated with the proposed sampling technique are compared against those foreseen by the sampling theory for several values of the sampling rate. The final result is a quantitative analysis that trades‐off accuracy and implementation costs of the measurement instruments and is a powerful control tool usable by networks managers to check the quality of service they are providing, to understand network internal dynamics and to design their monitoring systems.
Communication Theory: Letter: Multiuser Detection Analysis in DS‐CDMA Channel with Nakagami Fading
Authors: Novaković Dejan M. , Dukić Miroslav L. 
Published: September 2008

AbstractIn this paper the multiuser detection performance analysis‐ in synchronous direct sequence code division multiple access (DS‐CDMA) system using decorrelating and decision feedback (DFB) receivers, including single path Nakagami fading channel is presented. The lower bounds of the receivers bit error probability (BER) are derived, and the comparison of these receivers' performances to the conventional CDMA receiver is made. The analytical and numerical results show that the DFB receiver performs better in the presence of the high Nakagami fading channels.
Analysis of Ken Effect in IM/DD SCM Systems with Multiple Optical Carriers
Authors: Krishnaswa Rajesh M. , Sircar Pradip 
Published: September 2008

AbstractThe Kerr effect in an intensity modulated direct detection subcarrier multiplexed system with multiple optical carriers is investigated in this paper. An expression for inteference power spectrum is derived taking into consideration the laser phase noise and Kerr effect. The derivation is carried out first for the case of two optical carriers, and then generalised for the lightwave system with N optical camers.
Letter: Blind Adaptive Parameter Estimation for CDMA Systems using Cyclostationary Statistics
Authors: Mazzenga Franco 
Published: September 2008

AbstractIn this letter we present a time domain blind adaptive algorithm to jointly estimate amplitude, phase, and time delay of each user in a code division multiple access (CDMA) signal. It is based on the cyclostationary nature of the CDMA signal and it uses the estimates of normalized cyclic and conjugate cyclic autocorrelation functions of the received signal. Since the latter can be obtained as solution of a minimum mean square error optimization problem adaptive algorithms can be used to obtain an on line implementation of the procedure. Performances are evaluated through simulation.
Letter: Compressed Disparity Information Transmission over Constant Bit Rate ATM Channels
Authors: Papadimatos Dionysis , Antonakopoulos Theodore , Makios Vassilios 
Published: September 2008

AbstractThis letter presents a real‐time lossless compression/decompression unit for disparity map information used in 3D teleconferencing systems. A lossless compression algorithm is used to compress the disparity map data in real‐time, resulting in a variable bit‐rate data stream that has to be transmitted through a constant bit‐rate channel. The system uses a controlled‐data‐loss method for data rate adaptation and for minimizing the loss of information.
An Improved Linear MMSE Detection Technique for Multi‐Carrier CDMA Systems: Comparison and Combination with Interference Cancellation Schemes
Authors: Baudais Jean‐Yves , Hèlard Jean‐François , Citerne Jacques 
Published: September 2008

AbstractIn this paper, various detection techniques are studied in the synchronous case of a multiuser MC‐CDMA system operating in frequency selective Rayleigh channel. First of all, an improved linear detection approach named MMSE per user detection technique, which takes into account the despreading process, is presented. Simulation results over a Rayleigh fading channel show that this novel technique offers for non full load systems a significant gain compared to the MMSE equalization per camer method. Then, the performance of various parallel and successive interference cancellation techniques is compared to the performance of the linear MMSE per user scheme. When the power of the interferers is roughly equal to the power of the useful signal, the performance of the linear MMSE per user is really close to the performance of the non linear PIC and SIC schemes.
Spread Spectrum OFDM Modem for HF Voice‐Band Link over Fading Channels
Authors: Zazo Santiago , Bader Faouzi , Páez‐Borrallo José M. 
Published: September 2008

AbstractThis paper deals with the application of spread spectrum techniques to MultiCarrier HF modems. OFDM modems are a special option for the transmission over the high dispersive HF medium in front of single carrier modems. Our present contribution is now focused on the application of Spread Spectrum techniques to improve its fading robustness. The transmission bandwidth is the standard voice band channel in the HF band where the spread spectrum characteristic means that one symbol is transmitted over N times the spectrum in the classical N‐OFDM scheme. The motivation of this idea is the observation of the OFDM modems behaviour over fading channels with deep nulls showing a quite different performance between carriers: those in the vicinity of deep nulls provide a much higher Bit Error Rate (BER) than others far away of the nulls. Our proposal intends to spread different symbols over all the subcarriers simultaneously in order to homogenize performances. This approach, performed by orthogonal codes, shows an evident link with MC‐CDMA techniques. In addition, Multi User Detection (MUD) strategies as Interference Cancellation (IC) with coherent detection are also applied in order to improve its performance.
Flexible Implementation of Multicarrier Systems with Polyphase Filterbanks
Authors: Matheus Kirsten , Kammeyer Karl‐Dirk , Tuisel Ulrich 
Published: September 2008

AbstractThis article will emphasize on how to efficiently implement multicamer (MC‐) systems different from and alternative to OFDM with polyphase filterbanks. It will show that when using polyphase filterbanks this is an incomplex and flexible solution. It will be derived that with polyphase filterbanks an additional MC‐system design parameter exists; not only spacings between adjacent subcarriers in integer multiples of the inverse MC‐symbol duration are possible but that also non‐integer multiples of the inverse MC‐symbol duration are easily realizable.
On the assessment of cochannel interference in wireless systems by the saddle point approximation
Authors: Tomba Luciano 
Published: September 2008

AbstractMany papers have considered the problem of how to calculate theprobability of outagedue to cochannel interference in cellular radio systems. A general approach based on the characteristic function method has been recently presented in [1,2] and in [3] in the cases of Nakagami fading and Rice fading, respectively. However, closed—form results are available only in a few cases, while numerical integration and/or evaluation of special functions is the solution for other cases. In this paper we follow a similar approach as in the above works, but we evaluate integrals by using thesaddle point approximationmethod which has proven itself to be fast and accurate. Some comparisons between our results and the results published in the above references are reported.
Letter: On the performance of trellis coded M—PSK systems over rician fading channels with phase jitter
Authors: Uysal Mrat , Aygolu Umit , Panayirci Erdal 
Published: September 2008

AbstractIn this paper, the performance of trellis coded M—PSK systems is investigated operating over Rician fading channels with phase jitter. Thus the results reflect not only the degradation due to the effect of fading on the amplitude of the received signal, but also the impairment caused by the noisy carrier reference, which is usually neglected by the assumption of perfect phase tracking at the receiver. Analytical upper bounds on pairwise error probability for Rician fading with phase jitter are derived using Chernoff bounding technique in both cases where channel state information is available or not. The bit error probability performances are evaluated based on the modified transfer function approach. The numerical examples clearly demonstra'e the error performance degradation due to both amplitude fading and phase noise process.