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Communications, 1997. ICC '97 Montreal, Towards the Knowledge Millennium. 1997 IEEE International Conference on

Date 12-12 June 1997

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  • Proceedings of ICC'97 - International Conference on Communications

    Publication Year: 1997
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  • Conference Author Index

    Publication Year: 1997 , Page(s): 1745 - 1750
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  • Three-dimensional multiresolution video compression strategy for using human visual characteristics

    Publication Year: 1997 , Page(s): 1669 - 1673 vol.3
    Cited by:  Patents (1)
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    A new three-dimensional multiresolution video compression strategy by applying discrete wavelet transform (DWT) and discrete cosine transform (DCT) is proposed. Its results can bring about a wide range of application in condensed storage and archival of image sequences. Applications to video broadcasting, multimedia image database storage, image archive etc. would be appropriate View full abstract»

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  • Multiuser detection schemes applied to regional GEO satellite mobile systems

    Publication Year: 1997 , Page(s): 1236 - 1240 vol.3
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    Multiuser detection schemes are applied to a regional GEO satellite mobile system based on FDM/TDMA. The study focuses on the system uplink (mobile to satellite) and analyzes the performance of candidate schemes taken from the class of linear multiuser receivers. A new simple MMSE combiner is proposed, which provides performance close to optimal in terms of output MSE and lends itself to a simple adaptive implementation. Results pertaining to FDM/TDMA coded transmission with slow frequency hopping and short-depth interleaving are presented View full abstract»

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  • Self-healing mechanisms in ATM networks: the role of virtual path management functions

    Publication Year: 1997 , Page(s): 1719 - 1723 vol.3
    Cited by:  Papers (3)  |  Patents (2)
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    This paper proposes a new approach of VP testing and reporting functions and highlights the close co-operation that can be established between VP fault management and self-healing mechanisms in order to enhance the efficiency of the distributed recovery approaches in case of failures. The still unused fields in the operation and management flows defined for ATM networks can be reserved for self-healing requirements in order to prepare the restoration and consequently optimise ATM network protection View full abstract»

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  • A generalized grouping and retrieval scheme for stored MPEG video

    Publication Year: 1997 , Page(s): 1674 - 1678 vol.3
    Cited by:  Papers (5)
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    MPEG, in addition to being an international standard, is currently the most popular coding scheme for stored video. For several applications that require stored video, such as video-on-demand, it is advantageous to group MPEG frames into segments. Retrieving segments instead of individual frames can result in a more efficient use of disk retrieval resources and consequently, in the support of a larger number of users and in a more cost-effective system. Depending on the value of parameters such as desired user quality of service, size and cost of required buffers, number of disks to stripe a segment across, etc., a certain segment length (defined as the number of frames per segment) may be preferred over others. In this paper, we propose a generalized grouping scheme that may be used to achieve any desired segment length. Properties of such a grouping scheme and formulae that may be used to achieve such a grouping have been provided. Since a segment is an atomic unit of video retrieval, retrieval of some segments is skipped during fast playback. Some frames belonging to retrieved segments may be discarded due to the unavailability of other frames necessary for their decoding. Tradeoffs between different kinds of fast playback (i.e., the choice of skipped segments) and the number of discarded frames is discussed View full abstract»

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  • Performance of the COFDM systems with waveform shaping

    Publication Year: 1997 , Page(s): 1241 - 1245 vol.3
    Cited by:  Papers (2)
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    This paper explains the advantages of using a method for waveform shaping in COFDM. It is shown that such data shaping decreases the side lobes of the transmitted signal and minimizes the need for a guard band between OFDM systems. Classical OFDM systems based on DFT make use of a guard interval in order to improve the performance in multipath fading channels. A part of the loss due to the power transmitted during the guard interval can be compensated efficiently by the waveform shaping which is proposed. In the presence of both AWGN and multipath fading the bit error performance of the proposed system and the classical COFDM systems are compared. Digital video broadcasting is used as an example View full abstract»

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  • Smoothing algorithms for the delivery of compressed video

    Publication Year: 1997 , Page(s): 1330 - 1334 vol.3
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    The transport of compressed video without loss of picture quality requires the network to support large fluctuations in bandwidth requirements. This paper introduces a lossless smoothing algorithm designed to satisfy any given set of buffer and delay constraints for both stored and live video applications with the goal of minimizing the number of rate changes and maximum rate. The algorithm is shown to be effective in smoothing bursty bit streams as illustrated by the experimental demonstration of MPEG encoded video View full abstract»

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  • Characteristics of ABR explicit rate control algorithms in WAN environment

    Publication Year: 1997 , Page(s): 1396 - 1400 vol.3
    Cited by:  Papers (1)
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    This paper investigates the characteristics of ABR explicit rate control algorithms in the WAN environment. We also propose two new control algorithms based only on traffic measurement. An ABR service is expected to make it possible to utilize bandwidth effectively by closed-loop congestion control, and several control algorithms have been proposed. However, for WAN environment, a long propagation control delay will affect the effectiveness of control algorithms. Additionally, if a network supports large numbers of connections, some of the algorithms may not work well. Thus, we first categorize the aim and mechanism of control algorithms, including our proposed algorithms. Then, we evaluate their characteristics by simulation in WAN environment from the viewpoint of throughput, robustness, quickness, stability, and fairness. Using this analysis, we discuss their effectiveness in WAN environment View full abstract»

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  • Efficient time slot assignments for TDM multicast switching systems

    Publication Year: 1997 , Page(s): 1366 - 1370 vol.3
    Cited by:  Papers (3)
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    This paper focuses on designing efficient multicast time slot assignment (MTSA) algorithms for TDM switching systems, Based on a packet compatibility matrix, the MTSA can be transformed to the well-known graph-coloring problem. We show that the MTSA problem is NP-complete. A lower bound on the frame length of a multicast time slot assignment is then found to be the clique number of the MTSA equivalent graph. Two efficient MTSA algorithms, called the contention-based ordering (CBO) algorithm and the hybrid ordering algorithm, are proposed. Their performance is compared with the three existing algorithms and the lower bound through extensive simulations. We found that the CBO algorithm, which has one of the lowest computational complexities, gives the best performance among all five algorithms studied. The average frame length generated by the CBO algorithm is within 1% above the lower bound. We also show that (i) the previously reported DAC algorithm has the poorest performance despite its highest complexity, and (ii) the previously reported CCBO algorithm has only a comparable performance to the simple greedy algorithm View full abstract»

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  • A dynamic reservation protocol for multi-priority multi-rate data services on GSM networks

    Publication Year: 1997 , Page(s): 1261 - 1265 vol.3
    Cited by:  Papers (1)  |  Patents (2)
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    This paper presents a new media access control protocol for multi-priority multi-rate data services on GSM networks. In this protocol, which we named dynamic reservation protocol, data terminals can get their uplink channels through contention-free reservation. Therefore this protocol can achieve very high channel utilization efficiency and can significantly improve the service performance under heavy traffic load. The reservation scheme can adapt to traffic variations, by dynamically changing the transmission cycle length. Simulation results show that this protocol offers significantly better delay/throughput performance when compared to other protocols proposed in the literature. Since this protocol is built on the top of the GSM physical layer, its implementation should be very straight forward View full abstract»

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  • Moments of the first passage time to overload for a buffered statistical multiplexer

    Publication Year: 1997 , Page(s): 1689 - 1693 vol.3
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    We consider the first passage to overload for a buffered statistical multiplexer loaded with N identical binary on-off sources. First passage times to overload are related to the characterization of congestion imminence which in turn is crucial in the design of effective congestion control algorithms for delay sensitive services in broadband wide area networks. We give the moments of the first passage time to overload as solutions of a set of linear first order ordinary differential equations. Furthermore, adapting the methodology developed by Anick, Mitra and Sondhi (1982) we express the moments of the first passage time to overload in a spectral expansion form, involving the system's eigenvalues. Numerical results for the first two moments are presented View full abstract»

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  • Real-time cell loss estimation for ATM multiplexers with heterogeneous ON/OFF sources

    Publication Year: 1997 , Page(s): 1679 - 1683 vol.3
    Cited by:  Papers (2)
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    We are concerned with a real-time quality of service (QOS) estimation method for ATM statistical multiplexers with heterogeneous ON/OFF sources. We propose a real-time modeling method for the superposed traffic by a two-state MMPP by approximating the density function of aggregate cell arrival rate as a Bellows-like Poisson process. We also investigate a real-time calculation of the waiting time distribution for MMPP(2)/D/1 system to consider an upper bound of the cell loss ratio (CLR) for the finite-buffer system. Numerical examples show that the proposed QOS estimation method gives a good estimation of CLR View full abstract»

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  • Mapping wander in SONET/SDH adaptive threshold modulation pointer processors

    Publication Year: 1997 , Page(s): 1587 - 1591 vol.3
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    There are three types of pointer processors in synchronous optical network (SONET) and synchronous digital hierarchy (SDH) networks: traditional fixed threshold, uniform and adaptive threshold modulation. Fixed threshold pointer processors produce gapped pointer sequences as a result of the periodic effects of the SONET/SDH overhead bytes. These gapped pointer sequences cause wander when SONET/SDH carries PDH payloads. Uniform pointer processors smooth the gapped pointer sequences caused by the STM-N, AU and TU overhead bytes. Adaptive threshold modulation pointer processors (ATM-PPs) can also exhibit gapped pointer effects. This paper compares the wander from a gapped ATM-PP and the wander from a proposed uniform ATM-PP. The results indicate that this novel technique reduces wander View full abstract»

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  • Noncoherent continuous phase frequency-shift keying with trellis-coded modulation

    Publication Year: 1997 , Page(s): 1508 - 1512 vol.3
    Cited by:  Patents (1)
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    In this paper, we examine the design of a continuous phase frequency-shift keying (CPFSK) system with trellis-coded modulation (TCM) when the detection is noncoherent. A multi-symbol correlation method is used to provide improved branch metrics for the Viterbi decoder. A suboptimal detector structure is then created that provides essentially identical results with a decrease in complexity. Simulation results show that for adequate signal-to-noise ratios (SNRs), the noncoherent CPFSK-TCM system can out-perform a non-coded, noncoherent CPFSK system at the same bit rate and bandwidth. Work to design optimal codes is continuing View full abstract»

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  • Architecture for restorable call allocation and fast VP restoration in mesh ATM networks

    Publication Year: 1997 , Page(s): 1158 - 1163 vol.3
    Cited by:  Papers (1)  |  Patents (9)
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    This paper presents an architecture for restorable call allocation and fast virtual path (VP) restoration in mesh ATM networks. In this architecture, virtual working and spare capacities needed for call allocation and restoration are reserved and released dynamically on a call-by-call basis at the time of call admission and termination. The architecture does not require advance assignment of spare and working capacities. To shorten the call processing delay, this is done in a parallel-distributed fashion. To provide restorable call allocation, parallel-distributed call processing algorithms of the sender-chooser type are suggested. The algorithms integrate on the call level virtual bandwidth allocation, virtual spare capacity assignment with fixed, alternate, or state-dependent routing. Each routing scheme leads to a particular tradeoff between call processing complexity, call setup delay, and bandwidth efficiency. For each pair of nodes, two sets of VPs are provisioned. The first is a working VP (WVP) set, to be used for call allocation during the normal operation. The second is a spare VP (SVP) set, to be used for VP restoration in the event of failure of network elements (NE). Each SVP protects a preassigned subset of the node pair WVPs. Each SVP is selected to be link/node disjoint from the WVPs that it is assigned to protect. This assures protection of the WVP set by a small number of SVPs. Since SVPs are preset and appropriate virtual spare capacities are reserved in advance, the architecture guarantees full restorability and provides very fast restoration. The restoration is done on the VP level in a self-healing manner. The suggested architecture requires only local information to be maintained at each node View full abstract»

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  • Scheduling on airdisks: efficient access to personalized information services via periodic wireless data broadcast

    Publication Year: 1997 , Page(s): 1276 - 1280 vol.3
    Cited by:  Papers (7)
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    There has been considerable interest in delivering information to distributed mobile clients via wireless broadcast. Information transmitted periodically over wireless media can be regarded as a virtual disk, which we call an airdisk, analogous to a standard magnetic disk. Airdisks offer an efficient mechanism for delivering personalized information services to mobile clients with portable or laptop computers by broadcasting data and allowing clients to filter out the items of interest to them. We study the problem of scheduling the order in which data items are broadcast so as to minimize the access time of the clients, focusing on the case where the server inserts an index at the start of the broadcast period. We observe that the problem is analogous to that of determining how data should be laid out on the disk, and show that the problem is in general NP-complete. We develop a branch-and-bound procedure for solving the problem optimally, and then develop a fast, simple heuristic. The results of our simulation experiments show that the heuristic runs substantially faster than the branch-and-bound procedure, and yet produces schedules that are only slightly longer View full abstract»

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  • A scalable, dynamic multicast routing algorithm in ATM networks

    Publication Year: 1997 , Page(s): 1361 - 1365 vol.3
    Cited by:  Papers (3)  |  Patents (1)
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    In this paper, we present a scalable dynamic multicast routing algorithm based on a dynamic Steiner tree approach. First, we analyze a hierarchical multicast routing algorithm which introduced the use of core nodes in each peer-group to support multicasting under the private network-network interface (PNNI) framework. Based on this analysis, we conclude that finding near-optimal multicast trees in each peer-group is important. Our proposed algorithm produces improved results by computing better multicast trees within each peer-group. This scheme also eliminates the dependency of core node selection, on the quality of overall multicast tree generated. We compare the two schemes based on simulations on several randomly generated graphs of size ranging from 115 to 170 nodes. Based on these simulations, we show that our algorithm performs 35% better than the hierarchical algorithm. Our algorithm is scalable, allows incorporation of fault-tolerance and can easily be extended to incorporate a QoS criterion in routing View full abstract»

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  • Tap-selectable decision feedback equalization

    Publication Year: 1997 , Page(s): 1521 - 1526 vol.3
    Cited by:  Papers (3)  |  Patents (3)
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    This paper presents an adaptive tap assignment technique for improving the performance and robustness of a reduced-complexity decision-feedback equalizer (DFE) for broadband wireless mobile communications. The spacing of individual feedforward taps of the DFE is made variable such that, when the channel consists of sparsely-distributed multipath with a large delay spread (e.g., “hilly terrain” delay profiles), the feedforward taps can be sparsely assigned to increase the equalizer span without increasing the total number of the feedforward taps. We provide an analysis of the optimum tap assignment problem and propose a practical channel-estimation-based tap assignment algorithm which can be executed prior to equalizer training. Simulation results are obtained for various outdoor delay profiles with dispersions ranging up to several tens of symbol periods and while using only a small number of feedforward taps (e.g., 5 taps), compared to a conventional contiguous-tap DFE, the proposed tap-selectable DFE is found to give relatively stable performance (measured in terms of required SNR) over all profiles, and also to provide improved robustness to fast fading View full abstract»

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  • A MMSE interpolated timing recovery scheme for the magnetic recording channel

    Publication Year: 1997 , Page(s): 1625 - 1629 vol.3
    Cited by:  Papers (12)  |  Patents (8)
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    Advances in VLSI technology permit the use of interpolated timing recovery (ITR) as a replacement for the conventional VCO-based phase lock loop. Fully digital ITR has the advantage of lower cost and higher stability. In this paper, we present an interpolated timing recovery scheme that requires almost no oversampling, which should be suitable for high-speed storage channels View full abstract»

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  • A medium access protocol for interconnecting ATM and wireless networks

    Publication Year: 1997 , Page(s): 1448 - 1453 vol.3
    Cited by:  Papers (3)
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    This paper describes a medium access protocol for wireless ATM systems using time division multiple access with frequency division duplex. Voice and data mobiles are supported. In order to utilize the resource efficiently, information slots are allocated to mobiles that are in talkspurt only. When a mobile changes its state from silent to talkspurt, it has to request for an information slot. Real-time service is required for voice mobiles and so queueing is not allowed. The medium access scheme for voice mobiles is based on the non-collision packet reservation multiple access (NC-PRMA) which will ensure prompt delivery of voice packets. Data mobiles are considered as services that are delay-insensitive. Available bit rate services can be provided for (delay-insensitive) data mobiles. The scheme for data mobiles is based on the distributed queueing request update multiple access (DQRUMA). Numerical results are obtained through simulations and the performance of the proposed hybrid protocol is compared with that of PRMA and reservation TDMA. The results obtained show that the proposed protocol performs better in the sense of having smaller voice and data dropping probabilities under similar system conditions. Additional advantages are that optimization of the system throughput is easier and that the performance of voice mobiles is unaffected by instability in the data portion of the protocol View full abstract»

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  • A simple packet combining technique in frequency-hopped spread-spectrum multiple access communication networks

    Publication Year: 1997 , Page(s): 1207 - 1211 vol.3
    Cited by:  Patents (2)
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    In this paper, we propose a simple packet combining scheme in frequency-hopped spread spectrum multiple access (FH/SSMA) communication networks, which makes a tone-by-tone logical AND operation on the previously combined packet and the currently received (retransmitted) packet. The packet error probability is analyzed in the presence of multiple access interference (MAI) with AWGN or Rayleigh fading. It is found that the number of simultaneous users can be increased almost by a factor of two as compared to the conventional scheme, and the performance improvement becomes more significant, as the number of combined packets is increased. It is also found that for the packet error probability of 10-2 and M=8, a 2-4 dB gain in Eb /N0 can be obtained over the conventional scheme in the AWGN and Rayleigh fading channels, and the gain increases as M increases View full abstract»

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  • System stability for slotted ALOHA in heavy traffic region

    Publication Year: 1997 , Page(s): 1592 - 1596 vol.3
    Cited by:  Papers (2)
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    The problem of defining traffic regions for a slotted ALOHA model is introduced in the literature through the ergodicity analysis studied previously. In their work, the authors of the mentioned references devised a criterion on the estimate drift performance to guarantee system stability for traffic below an upper bound. This paper extends the estimate drift analysis and introduces the joint true versus estimate drift analysis to design the control parameters which guarantee system stability above the upper bound mentioned, and thus in any traffic region View full abstract»

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  • Minimizing maximum logical link congestion in packet switched optical networks

    Publication Year: 1997 , Page(s): 1298 - 1302 vol.3
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    We consider the problem of designing logical optical network topology for a given physical topology (or fiber layout) and a given traffic demand matrix between the end-users. Traffic between the end-users is carried in a packet-switched form and the objective of our logical topology design is to minimize the maximum congestion on the logical links in the logical topology. The logical links are realized by wavelength continuous paths or between end-users and they are routed via wavelength-selective routers. Note that a topology with lower maximum link congestion will allow its traffic demand matrix to be scaled up by a larger factor. In the logical topology, each node is equipped with a limited number of optical transceivers, hence logical connections cannot be set-up between every pair of nodes. In this paper we present an analytical model for obtaining the maximum and average logical link loads for a given logical network and traffic demand matrix. The model is confirmed via simulation. A heuristic algorithm for constructing a logical topology that reduces maximum logical link congestion is also presented View full abstract»

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  • A new oscillation avoid flow control scheme using explicit rate indications

    Publication Year: 1997 , Page(s): 1422 - 1426 vol.3
    Cited by:  Papers (1)
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    This paper presents a new ABR flow control scheme using explicit rate information in backward RM cells. Recording to this scheme, a network can dynamically allocate bandwidth resource by using the global information called the loadlevel of the network. It's much faster for all the ABR sources in the network to reach their optimal rates. The available bit rates the ABR sources obtain go up from their minimal fairshares to their maximal fairshares monotonously. In this sense the scheme is oscillation avoid View full abstract»

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