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Communications, Computers and signal Processing, 2001. PACRIM. 2001 IEEE Pacific Rim Conference on

Date 26-28 Aug. 2001

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  • 2001 IEEE Pacific Rim Conference on Communications, Computers and Signal Processing (IEEE Cat. No.01CH37233)

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  • Author index

    Page(s): 753 - 755
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  • A new adaptive filter structure: comparative study of NLMS, DST-LMS and DCT-LMS schemes applied to electromyographic signal modelling

    Page(s): 555 - 558 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB) |  | HTML iconHTML  

    The goal of this work is to present a transform domain algorithm called discrete sine transform with axis rotation LMS adaptive filter. Based on the least-mean-square (LMS) and discrete sine transform with axis rotation (DSTr) equations, a proposed algorithm is deduced. The authors compare its performance, through computer simulations, with normalized LMS (NLMS), discrete sine transform LMS (DST-LMS) and discrete cosine transform LMS (DCT-LMS) schemes. Another goal of this paper is the study of electromyographic (EMG) signal modeling using the DSTr-LMS algorithm. This is a type of signal that can be represented by an autoregressive model of the fourth order. Using an adaptive filter with adequate order as a predictor, its coefficients can be viewed as a representation of this signal. The learning curves of DSTr-LMS exhibit a better convergence rate and equivalent values of steady state mean-square error (MSE) if compared with learning curves of the other algorithms already mentioned. Therefore, the authors conclude that this set of coefficients is a good representation of this type of signal View full abstract»

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  • Agent-based personalized services in a mobile computing environment

    Page(s): 728 - 731 vol.2
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    This paper proposes an agent-based service provisioning system for mobile users. It features a set of cooperative agents distributed over different sites that work together to provide personalized services for users within a mobile computing environment. For instance, when a user moves outside of his office, he would like to have a similar office environment while he is at home, in a meeting at another company, on a business trip or at a temporary location such as a hotel. Agents representing the end-users and the system agents may engage into a negotiation process to help the user access personalized services at particular site in accordance with the user's home policies and his current location policies. Adaptive Service Presentation agent is used to adapt the service presentation to the capabilities of the user's device (e.g. Workstation, Laptop, Phone, PDA). This work is part of the Mobile Agent Alliance project involving University of Ottawa, National Research Council and Mitel Corporation in Canada View full abstract»

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  • Optimal design of multi-channel transmultiplexers with stopband energy constraints

    Page(s): 559 - 562 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB) |  | HTML iconHTML  

    Optimal design incorporating filters' stopband energy constraints for multi-channel, uniform and non-uniform transmultiplexers is studied. Central to the development is a reformulation of the design problem as a quadratically constrained quadratic programming problem where the stopband energy requirements are met by imposing a systems of quadratic constraints while the composite distortion measure proposed for reconstruction is minimized. An iterative optimal design procedure for FIR, synthesis filters and analysis filters is developed and applied to two design examples, one for the uniform case and the other for the nonuniform case View full abstract»

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  • A concealment scheme for H.263 coded video transported over the Internet using the RTPUDPIP protocol

    Page(s): 465 - 468 vol.2
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    Packet video with real-time constraints, limited bandwidth, multicast distribution, and using the RTPUDPIP protocol must take into account packet losses (with a large payload size) due to network congestion. An effective solution for packet loss is to perform concealment at the receiver. In this paper, we propose a concealment scheme for the 'I' frame missing odd or even slices that address the above problems. The proposed concealment scheme uses the previous frame macroblock (MB) or the MB motion vector (MV) with a fast motion estimation algorithm, located at the same spatial location as the missing MB. The decision between the MB or MB MV with a fast motion estimation algorithm is determined by the amount of motion between the decoded upper and lower 1 pixel wide boundary (if available) of the missing MB and the MB located in same spatial location in the previous frame. The proposed scheme produced similar peak signal to noise ratio (PSNR) results while the Central Processing Unit (CPU) time is reduced by a factor of 30 when compared to the full search concealment technique View full abstract»

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  • Ultrashort light pulse CDMA with simultaneous fiber dispersion and dispersion slope compensation

    Page(s): 382 - 385 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB) |  | HTML iconHTML  

    We evaluate a fiber link for simultaneously compensating fiber dispersion and dispersion slope in ultrashort light pulse code-division multiple access (CDMA) communication systems. The fiber link consists of a standard single-mode fiber (SMF) connected with two different types of dispersion-compensating fibers (DCF). This fiber link demonstrates several tens of times longer transmission, compared to a dispersion-shifted fiber (DSF) link View full abstract»

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  • TRES: traffic and reliability engineering server for MPLS

    Page(s): 583 - 586 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB) |  | HTML iconHTML  

    Recently, Internet and intranet traffic has grown exponentially, increasing congestion and making operation of the backbone network difficult. Traffic engineering is needed for balancing the traffic load on the network, and it also helps in defining a policy for network operation. Reliability engineering is needed for protecting network connectivity in the even of a link or a node failure. In response to these demands, we have developed a server named TRES (traffic and reliability engineering server). TRES calculates and sets wide bandwidth paths while satisfying many policy constraints. It also provides path rerouting in the event of a link or a node failure View full abstract»

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  • A Hammerstein type equalizer for the Wiener type fiber-wireless channel

    Page(s): 546 - 549 vol.2
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    Nonlinear distortion of the radio-over-fiber (ROF) link and multipath dispersion of the wireless link are the two major factors that limit the performance of a fiber based wireless access scheme. This is especially true when the radio frequency is only a few GHz. In this paper, we propose a Hammerstein type decision feedback equalizer (HDFE) that compensates for both the nonlinear distortion and the linear dispersion. The proposed receiver has notably less complexity because the linear and nonlinear compensations are done separately. This also enables tracking of the fast changing wireless channel independent of compensation of the relatively static nonlinearity. Analytical and simulation results show that the performance of this receiver in a nonlinear channel approaches that of a conventional decision feedback equalizer in a linear channel when, the nonlinearity is memoryless and the inverse of the channel is a realizable finite polynomial View full abstract»

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  • A high-speed baseband transceiver for wireless communications using QAM

    Page(s): 631 - 634 vol.2
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    A baseband transceiver using multi-level of QAM was designed to satisfy the needs in a wireless communication system. The design takes advantages of novel algorithms and circuits in the implementation of the forward error correction to achieve a BER of 10-12 while maintaining a small size, low cost and high-speed system View full abstract»

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  • Complex Chebyshev approximation to stable IIR filters design

    Page(s): 563 - 566 vol.2
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    This paper presents a minimax design method of stable IIR digital filters with an arbitrary magnitude and phase response using the successive projection (SP) method. Because the design of IIR filters generally results in a complex approximation problem, the complex approximation problem is converted into a real approximation problem and its problem is solved using the SP method. Then, we use the implications of Rouche's theorem to modify the SP method in such a way that a constraint on the maximum pole radius can be incorporated. Hence, the filters obtained can be guaranteed to be stable and are optimum in the Chebyshev sense View full abstract»

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  • Experimental evaluation of MPEG-2 video over differentiated services IP networks

    Page(s): 469 - 472 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB) |  | HTML iconHTML  

    As multimedia find their way in many applications and services, and with Internet's undisputed success as the networking technology of the future for the provision of integrated services, it became necessary that these two technologies interoperate effectively with each other. The real-time quality of service requirements of many multimedia applications involving video, audio etc., can not be satisfied by the best effort scenario, which is the basis of operation for the first generation of Internet. In order to make Internet quality of service (QoS) capable, IETF proposed a series of protocols and algorithms, some of them forming what is known as "Differentiated Services". In this paper, we evaluate the performance of MPEG-2 video over a Diffserv-capable network. Our extensive testing results give a very promising picture. With proper resource management and traffic engineering, differentiated services can provide satisfactory QoS to applications with serious delay and delay variation, packet loss and throughput requirements, such as MPEG-2 video View full abstract»

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  • ASA: the Active Service Architecture for new Internet

    Page(s): 489 - 492 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (352 KB) |  | HTML iconHTML  

    Because support of new distributed multimedia applications are an important challenge for the Internet service providers, a lot of works are under progress for enhancing the Internet architecture. Thus, Internet service architectures based upon new protocols have been proposed. While a new generation of the Internet may be developed from these proposals, the problem of the deployment of these new technologies becomes of a prime importance. We attempt to provide a solution to the Internet evolution process by means of a new concept, the Active Service Architecture (ASA), that is based on the new technology of active networking. The concept of activity in the ASA architecture is presented, specification of the nodes are given and an experimentation of active service is shown View full abstract»

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  • Managing design patterns in MAKE style

    Page(s): 409 - 412 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB) |  | HTML iconHTML  

    In this investigation we propose how to manage evolution of design patterns that consist of parameterized design documents and templated software (or sample codes). Whenever design patterns are evolved, dependency among them are examined and designers are notified that there might be some inconsistency among the patterns. We discuss such features based on dependency-detection mechanism that are found in MAKE View full abstract»

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  • A new optimal transmit and receive diversity scheme

    Page(s): 538 - 541 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (264 KB) |  | HTML iconHTML  

    The effects of fading in mobile radio channels can be mitigated with the use of space (or antenna) diversity. One diversity scheme which is applicable to any number of transmit and receive antennas is maximum ratio transmission (MRT). In this paper, it is shown that a certain constraint on the MRT receiver combining weights results in performance degradation. A new transmit and receive diversity scheme, MRTC, is proposed which maximizes the output signal-to-noise ratio (SNR). The MRTC scheme optimizes the transmit and receive weights. It is found that MRTC can offer significant gains over MRT. Another slightly sub-optimal but simpler-to-implement diversity scheme, IMRT, is also proposed. The IMRT scheme uses the same transmit weights as MRT; however, in contrast to MRT, it uses optimal MRC-based receive weights View full abstract»

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  • Scheduling algorithm with priority of active buffer for variable-length IP packet over input-buffered ATM switch

    Page(s): 526 - 529 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB) |  | HTML iconHTML  

    In the input buffered ATM (asynchronous transfer mode) switches, HoL (head of line) blocking can be eliminated entirely by VOQ (virtual output queuing), in which each input port maintains a separate buffer for each output port. On the other hand, the IP (Internet protocol) traffic has increased explosively, therefore to manage IP packets over ATM, IP-PIM (IP-parallel iterative matching) has been proposed. However, the queue length of other buffers increases with IP-PIM, since the cells of some packets are switched consecutively. Therefore, IP-PIM causes degradation of the packet loss probability. In this paper, by defining the buffer at which cells that belong to a packet arrive in a certain time slot as an active buffer, we propose a new scheduling algorithm that gives priority to an active buffer so that cells which belong to packets can be switched effectively without increasing the queue length. We evaluate the packet loss probability and the mean packet delay by computer simulations. As a result, it is shown that the proposed scheme can improve the packet loss probability with negligible degradation of the mean packet delay View full abstract»

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  • Adaptive motion estimation algorithm using spatial and temporal correlation

    Page(s): 473 - 476 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB) |  | HTML iconHTML  

    Block motion estimation using full search is computationally intensive. Previously proposed fast search algorithms limit the size of search window, the size of sequence (usually QCIF format) and search locations. These algorithms do not fit for sequences having large motion or larger picture size. In this paper, we present a new fast and efficient search algorithm for block motion estimation that produce better performance in quality than TSS and 4SS and less computational time. The proposed algorithm is based on the idea of selecting an adaptive search window per macro-block using 3 spatial macro-blocks and one temporal macro-block with the distance criterion without computational burden. The result of simulation shows not only better quality of pictures than that of TSS and 4SS, but also faster execution time. Therefore it can be good solution for the real time multimedia mobile systems View full abstract»

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  • TAT: traffic analysis tool for the statistical study of IP networks

    Page(s): 579 - 582 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (600 KB) |  | HTML iconHTML  

    We present a new software package, TAT, that allows the statistical study of the IP traffic transmitted through an Internet node. This tool has been successfully tested under work carried out in a subnet of the regional network of Murcia (Spain) called Ciez@net. Cieza is a town of 30,000 people where the pilot network Ciez@net intends to give these people the opportunity to use the new emerging Internet applications in their daily life. The goal of the traffic analysis tool developed in this project has been to analyse the IP traffic transmitted in the regional network in order to figure out if the use that people make of the network services and infrastructure was worth the economic effort put into the network deployment and operation. The success of this software tool lies in its flexibility, easy handling and interface independence View full abstract»

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  • An implementation of inter processor communication for narrowband network interworking in ATM switching system

    Page(s): 522 - 525 vol.2
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    We have proposed the structure of an interworking system and the method of inter processor communication for providing existing narrowband network interworking in ATM switching system. The proposed interworking module consists of 8 low speed application specific units (LASU), 3 high speed application specific units (HASU) and a interworking control processor (IWP). The LASU and the HASU are application specific and the IWP is application independent. From the interworking point of view, application specific means non-ATM function such as DS1/E1/DS3 frame relay service and circuit emulation service and application independent means common ATM function. The inter processor communication function is to transfer call control messages, OAM messages, TDM channel establishment messages between the main processor and interworking processor View full abstract»

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  • Efficient and fast predictive block motion estimation for low bit rate video coding

    Page(s): 477 - 480 vol.2
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    An efficient block based motion estimation algorithm is proposed and evaluated for performance improvement. Spatio-temporal correlation characteristics and histograms of motion vector magnitude and direction are investigated through computer simulation with test video sequences. Its initial search pixel location is predicted spatially from the neighboring macro block in the current picture frame. In order to utilize center oriented motion vector characteristics from the histogram analysis, fast estimation algorithms such as three step search, diamond search, 2D logarithmic search and 1-D gradient search are evaluated and compared in terms of its search performance with respect to Euclidean search distance. A new predictive 1-D gradient search algorithm is proposed which shows the best results for motion video having moderate motion inside and is applicable for low bit rate video coding such as video telephony. Computer simulation using test video sequences in the H.263 framework shows that the proposed algorithm reduces computation cost measured in the number of SAD calculations. Its compression quality represented in terms of PSNR is improved further than conventional methods by controlling the search termination condition. It is proved that the proposed algorithm improves the search speed as well as PSNR performance of 1-D gradient motion estimation and outperformed other fast algorithms with respect to search speed. Furthermore, its search performance can be traded off with computation cost according to application requirements View full abstract»

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  • Smooth loss with variability smoothing factor to increase bandwidth utilization

    Page(s): 493 - 494 vol.2
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    As the rapid growth of the Internet data streaming the TCP and UDP protocols could not efficiently utilize and share bandwidth for the data streaming. There are many techniques to improve a transmission data stream to archive multimedia data. The adaptive transmission control using smoothed loss is a technique that controls the transmission rate to an appropriate network condition. This paper improves this technique by using a variability smoothing factor which can improve the transmission rate in the whole transmission. Simulations are used to study an adaptive behavior of the adaptive transmission control procedure. The results of experiment shows that a rate adaptive control procedure can increase the transmission rate by using a variability smoothing factor View full abstract»

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  • Wireless IP network architecture for cdma2000

    Page(s): 354 - 356 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB) |  | HTML iconHTML  

    In the industry trend toward third generation (3G) cellular systems, a great deal of emphasis has been placed on packet based transport, especially by adapting the Internet Protocol. At the same time, there is a trend across the communications industry to converge voice and data at the transport level. The interests of the major players are accelerating the development of new standards and availability of new products to support the benefits of convergence. It is now possible to employ existing VoIP technology solutions currently available to provide CDMA systems that are based on third generation system architectures. This paper discusses the migration from fundamentally circuit switched solutions for wireless voice toward packet switched, IP based solutions for cdma2000 system View full abstract»

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  • The condition of improving throughput both of high and low priority at the same time

    Page(s): 611 - 614 vol.2
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    There is a conservation law that states that the sum of the average queuing delays within a set of multiplexed flow is independent of priority control. However with reference to ARQ specifically, we can adopt the idea of "goodput" (normalized throughput) to evaluate the efficiency of the transmission. With this, we discover that there are cases when the goodput of high-prioritized and low-prioritized flows can both improve at the same time. To achieve this, we will need routers that are able to handle priority control adaptively. This is confirmed theoretically in this paper, which uses a simple go-back-N model as a basis for calculation View full abstract»

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  • Extension of service location protocol for IPv6 communication mobility

    Page(s): 495 - 497 vol.2
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    IPv6 Communication Mobility (IPCM) is a new concept enabling to redirect an IPv6 communication from a station to another one. The mechanisms used are related to SLP (Service Location Protocol) mechanisms. We present communication mobility, and a solution for IPv6 using several mechanisms already implemented in SLP or in Mobile IPv6 View full abstract»

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  • Buried heterostructure lasers for metropolitan area networks: anomalous low temperature behaviour

    Page(s): 386 - 388 vol.2
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    Buried heterostructure (BH) lasers are key sources for optical fibre communication systems and integrated optoelectronics. We have initiated a study of the low-temperature behaviour of these lasers with a view to gaining insight into the mechanisms which limit their performance as directly modulated sources for optical communications systems. In particular, we have focussed on the effect of quantum transport bottlenecking during ambipolar injection across quantum wells, a mechanism widely viewed as responsible for limiting these lasers to operating below their ultimate modulation bandwidth View full abstract»

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