3,057 research outputs found
Architecture, design, and modeling of the OPSnet asynchronous optical packet switching node
An all-optical packet-switched network supporting multiple services represents a long-term goal for network operators and service providers alike. The EPSRC-funded OPSnet project partnership addresses this issue from device through to network architecture perspectives with the key objective of the design, development, and demonstration of a fully operational asynchronous optical packet switch (OPS) suitable for 100 Gb/s dense-wavelength-division multiplexing (DWDM) operation. The OPS is built around a novel buffer and control architecture that has been shown to be highly flexible and to offer the promise of fair and consistent packet delivery at high load conditions with full support for quality of service (QoS) based on differentiated services over generalized multiprotocol label switching
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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
Statistical multiplexing of video sources for packet switching networks
Communication networks are fast evolving towards truly integrated networks handling all types of traffic. They employ integrated switching technologies for voice. video and data. Statistical or asynchronous time division multiplexing of full motion video sources is an initial step towards packetized video networks. The main goal is to utilize the common communication channel efficiently, without loosing quality at the receiver. This work discusses the concept of using statistical multiplexing for packet video communications. The topology of a single internal packet network to support ISDN services has been adopted. Simulations have been carried out to demonstrate the statistical smoothing effect of packetized video in the networks having high speed links. Results indicate that the channel rate per source decreased in an exponential manner as the number of sources increased. An expression for the average usage time t of the channel has been derived in terms of channel rate per source and the number of sources multiplexed. Also the average usage time of the channel is higher for buffered data than that of the multiplexed data. The high speed communication links in the internal network are lightly loaded, which indicates that these links can accommodate more data
Congestion Control for Network-Aware Telehaptic Communication
Telehaptic applications involve delay-sensitive multimedia communication
between remote locations with distinct Quality of Service (QoS) requirements
for different media components. These QoS constraints pose a variety of
challenges, especially when the communication occurs over a shared network,
with unknown and time-varying cross-traffic. In this work, we propose a
transport layer congestion control protocol for telehaptic applications
operating over shared networks, termed as dynamic packetization module (DPM).
DPM is a lossless, network-aware protocol which tunes the telehaptic
packetization rate based on the level of congestion in the network. To monitor
the network congestion, we devise a novel network feedback module, which
communicates the end-to-end delays encountered by the telehaptic packets to the
respective transmitters with negligible overhead. Via extensive simulations, we
show that DPM meets the QoS requirements of telehaptic applications over a wide
range of network cross-traffic conditions. We also report qualitative results
of a real-time telepottery experiment with several human subjects, which reveal
that DPM preserves the quality of telehaptic activity even under heavily
congested network scenarios. Finally, we compare the performance of DPM with
several previously proposed telehaptic communication protocols and demonstrate
that DPM outperforms these protocols.Comment: 25 pages, 19 figure
The Statistical Analysis of the Live TV Bit Rate
This paper studies the statistical nature of TV channels streaming variable
bit rate distribution and allocation. The goal of the paper is to derive the
best-fit rate distribution to describe TV streaming bandwidth allocation, which
can reveal traffic demands of users. Our analysis uses multiplexers channel
bandwidth allocation (PID) data of 13 TV live channels. We apply 17 continuous
and 3 discrete distributions to determine the best-fit distribution function
for each individual channel and for the whole set of channels. We found that
the generalized extreme distribution fitting most of our channels most
precisely according to the Bayesian information criterion. By the same
criterion tlocationscale distribution matches best for the whole system. We use
these results to propose parameters for streaming server queuing model. Results
are useful for streaming servers scheduling policy design process targeting to
improve limited infrastructural resources, traffic engineering through dynamic
routing at CDN, SDN
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
A Micro Power Hardware Fabric for Embedded Computing
Field Programmable Gate Arrays (FPGAs) mitigate many of the problemsencountered with the development of ASICs by offering flexibility, faster time-to-market, and amortized NRE costs, among other benefits. While FPGAs are increasingly being used for complex computational applications such as signal and image processing, networking, and cryptology, they are far from ideal for these tasks due to relatively high power consumption and silicon usage overheads compared to direct ASIC implementation. A reconfigurable device that exhibits ASIC-like power characteristics and FPGA-like costs and tool support is desirable to fill this void. In this research, a parameterized, reconfigurable fabric model named as domain specific fabric (DSF) is developed that exhibits ASIC-like power characteristics for Digital Signal Processing (DSP) style applications. Using this model, the impact of varying different design parameters on power and performance has been studied. Different optimization techniques like local search and simulated annealing are used to determine the appropriate interconnect for a specific set of applications. A design space exploration tool has been developed to automate and generate a tailored architectural instance of the fabric.The fabric has been synthesized on 160 nm cell-based ASIC fabrication process from OKI and 130 nm from IBM. A detailed power-performance analysis has been completed using signal and image processing benchmarks from the MediaBench benchmark suite and elsewhere with comparisons to other hardware and software implementations. The optimized fabric implemented using the 130 nm process yields energy within 3X of a direct ASIC implementation, 330X better than a Virtex-II Pro FPGA and 2016X better than an Intel XScale processor
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