2,113 research outputs found
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Survey of traffic control schemes and error control schemes for ATM networks
Among the techniques proposed for B-ISDN transfer mode, ATM concept is considered to be the most promising transfer technique because of its flexibility and efficiency. This paper surveys and reviews a number of topics related to ATM networks. Those topics cover congestion control, provision of multiple classes of traffic, and error control. Due to the nature of ATM networks, those issues are far more challenging than in conventional networks. Sorne of the more promising solutions to those issues are surveyed, and the corresponding results on performance are summarized. Future research problems in ATM protocol aspect are also presented
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Survey of congestion control techniques for an ATM network
The emerging broadband integrated services digital network is expected to adopt ATM (Asynchronous Transfer Mode) as the transport network. This new network must support several classes of service with varying delay and loss requirements. It must also operate with link speeds in the hundreds of megabits per second and be scalable up to potential link speeds on the order of gigabits per second. The requirements to support multiple services and high speed make the congestion control in an ATM network difficult. This paper reviews sorne of the techniques for prevention and control of congestion in an ATM network
Integration Protocols for Voice and Data Traffic
Increasing demands for multimedia services offer integration of multimedia
traffic as a hot issue in the future research areas. As a result, in the literature, many
multiplexing schemes have been proposed. However, most of them have been
implemented with a high complexity, others may be non-effective to satisfy the
multiplexing performance criteria, while the rest are still not subjected to a wide
range of analysis. Therefore, there is a critical need for comparing some of the
recommended multiplexing schemes as well as developing a simple and effective
integration protocol while still achieving reasonable bandwidth utilization.
This thesis is intended to examine integration protocols for multimedia traffic,
with primary focusing on voice-data integration. Firstly, a survey of the existing
multiplexing schemes and related issues are presented. Next, an Adaptive Round
Robin (ARR) protocol is proposed, as an alternative for voice-data integration, and
extensively simulated. Finally, further comparisons, based on computer simulations,
are carried out for various multiplexing schemes including Strictly Priority Servicing
(SPS), Fixed Round Robin (FRR), Dynamic Bandwidth Allocation/(T1, T2) and
Queue Length Threshold (QLT).As a contribution of the thesis, the proposed protocol tries to avoid the
drawbacks of the previous multiplexing schemes besides satisfying the multiplexing
performance criteria. The protocol differs from the others in that, it gives a limited
priority for voice over data, it organizes the incoming packets to the single First-in
First-out (FIFO) output buffer rather than the only outgoing scheduling, i.e., all data
sources are polled in order according to the adaptation policy; however, before a data
source can send a packet, all active voice sources are polled in order. Thus it
provides an improvement in voice delay performance without significant effect on
data delay performance over previous protocols. In addition, simulation comparisons
between various multiplexing schemes have been discussed. In these simulations
voice packets are assumed to be generated from on-off sources (talkspurt-silence
calls), which is closer to reality and which is not considered in most of the
performance analyses of previous schemes
Dynamic bandwidth allocation in ATM networks
Includes bibliographical references.This thesis investigates bandwidth allocation methodologies to transport new emerging bursty traffic types in ATM networks. However, existing ATM traffic management solutions are not readily able to handle the inevitable problem of congestion as result of the bursty traffic from the new emerging services. This research basically addresses bandwidth allocation issues for bursty traffic by proposing and exploring the concept of dynamic bandwidth allocation and comparing it to the traditional static bandwidth allocation schemes
Some aspects of traffic control and performance evaluation of ATM networks
The emerging high-speed Asynchronous Transfer Mode (ATM) networks are expected to integrate through statistical multiplexing large numbers of traffic sources having a broad range of statistical characteristics and different Quality of Service (QOS) requirements. To achieve high utilisation of network resources while maintaining the QOS, efficient traffic management strategies have to be developed. This thesis considers the problem of traffic control for ATM networks. The thesis studies the application of neural networks to various ATM traffic control issues such as feedback congestion control, traffic characterization, bandwidth estimation, and Call Admission Control (CAC). A novel adaptive congestion control approach based on a neural network that uses reinforcement learning is developed. It is shown that the neural controller is very effective in providing general QOS control. A Finite Impulse Response (FIR) neural network is proposed to adaptively predict the traffic arrival process by learning the relationship between the past and future traffic variations. On the basis of this prediction, a feedback flow control scheme at input access nodes of the network is presented. Simulation results demonstrate significant performance improvement over conventional control mechanisms. In addition, an accurate yet computationally efficient approach to effective bandwidth estimation for multiplexed connections is investigated. In this method, a feed forward neural network is employed to model the nonlinear relationship between the effective bandwidth and the traffic situations and a QOS measure. Applications of this approach to admission control, bandwidth allocation and dynamic routing are also discussed. A detailed investigation has indicated that CAC schemes based on effective bandwidth approximation can be very conservative and prevent optimal use of network resources. A modified effective bandwidth CAC approach is therefore proposed to overcome the drawback of conventional methods. Considering statistical multiplexing between traffic sources, we directly calculate the effective bandwidth of the aggregate traffic which is modelled by a two-state Markov modulated Poisson process via matching four important statistics. We use the theory of large deviations to provide a unified description of effective bandwidths for various traffic sources and the associated ATM multiplexer queueing performance approximations, illustrating their strengths and limitations. In addition, a more accurate estimation method for ATM QOS parameters based on the Bahadur-Rao theorem is proposed, which is a refinement of the original effective bandwidth approximation and can lead to higher link utilisation
Statistical multiplexing and connection admission control in ATM networks
Asynchronous Transfer Mode (ATM) technology is widely employed for the transport of network traffic, and has the potential to be the base technology for the next generation of global communications. Connection Admission Control (CAC) is the effective traffic control mechanism which is necessary in ATM networks in order to avoid possible congestion at each network node and to achieve the Quality-of-Service (QoS) requested by each connection. CAC determines whether or not the network should accept a new connection. A new connection will only be accepted if the network has sufficient resources to meet its QoS requirements without affecting the QoS commitments already made by the network for existing connections. The design of a high-performance CAC is based on an in-depth understanding of the statistical characteristics of the traffic sources
System level performance of ATM transmission over a DS-CDMA satellite link.
PhDAbstract not availableEuropean Space Agenc
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