3,033 research outputs found
A Modeling Framework for Schedulability Analysis of Distributed Avionics Systems
This paper presents a modeling framework for schedulability analysis of
distributed integrated modular avionics (DIMA) systems that consist of
spatially distributed ARINC-653 modules connected by a unified AFDX network. We
model a DIMA system as a set of stopwatch automata (SWA) in UPPAAL to analyze
its schedulability by classical model checking (MC) and statistical model
checking (SMC). The framework has been designed to enable three types of
analysis: global SMC, global MC, and compositional MC. This allows an effective
methodology including (1) quick schedulability falsification using global SMC
analysis, (2) direct schedulability proofs using global MC analysis in simple
cases, and (3) strict schedulability proofs using compositional MC analysis for
larger state space. The framework is applied to the analysis of a concrete DIMA
system.Comment: In Proceedings MARS/VPT 2018, arXiv:1803.0866
Coded Computation Against Processing Delays for Virtualized Cloud-Based Channel Decoding
The uplink of a cloud radio access network architecture is studied in which
decoding at the cloud takes place via network function virtualization on
commercial off-the-shelf servers. In order to mitigate the impact of straggling
decoders in this platform, a novel coding strategy is proposed, whereby the
cloud re-encodes the received frames via a linear code before distributing them
to the decoding processors. Transmission of a single frame is considered first,
and upper bounds on the resulting frame unavailability probability as a
function of the decoding latency are derived by assuming a binary symmetric
channel for uplink communications. Then, the analysis is extended to account
for random frame arrival times. In this case, the trade-off between average
decoding latency and the frame error rate is studied for two different queuing
policies, whereby the servers carry out per-frame decoding or continuous
decoding, respectively. Numerical examples demonstrate that the bounds are
useful tools for code design and that coding is instrumental in obtaining a
desirable compromise between decoding latency and reliability.Comment: 11 pages and 12 figures, Submitte
Design and Performance of Scalable High-Performance Programmable Routers - Doctoral Dissertation, August 2002
The flexibility to adapt to new services and protocols without changes in the underlying hardware is and will increasingly be a key requirement for advanced networks. Introducing a processing component into the data path of routers and implementing packet processing in software provides this ability. In such a programmable router, a powerful processing infrastructure is necessary to achieve to level of performance that is comparable to custom silicon-based routers and to demonstrate the feasibility of this approach. This work aims at the general design of such programmable routers and, specifically, at the design and performance analysis of the processing subsystem. The necessity of programmable routers is motivated, and a router design is proposed. Based on the design, a general performance model is developed and quantitatively evaluated using a new network processor benchmark. Operational challenges, like scheduling of packets to processing engines, are addressed, and novel algorithms are presented. The results of this work give qualitative and quantitative insights into this new domain that combines issues from networking, computer architecture, and system design
On limits of embedded systems in network packet processing
The paper deals with a measurement of single-hop one way packet delay on embedded systems used for networking. The single-hop one way packet delay is essential parameter when we need to process packets with strict delivery time constrains. Comparison of different approaches to single-hop one way packet delay measurements is presented in this work along with discussion about strong and weak points in specific measurement approach. The impact of different types of system load and number of CPU cores are also covered by presented results. The presented results of measurement single-hop one way packet delay in embedded Linux system show that for the specific system configuration the packet processing delay depends (in different ways) on system load and network stack load
Network emulation focusing on QoS-Oriented satellite communication
This chapter proposes network emulation basics and a complete case study of QoS-oriented Satellite Communication
A Network Congestion control Protocol (NCP)
The transmission control protocol (TCP) which is the dominant
congestion control protocol at the transport layer is proved to have
many performance problems with the growth of the Internet. TCP for
instance results in throughput degradation for high bandwidth delay
product networks and is unfair for flows with high round trip delays.
There have been many patches and modifications to TCP all of which
inherit the problems of TCP in spite of some performance improve-
ments.
On the other hand there are clean-slate design approaches of the
Internet. The eXplicit Congestion control Protocol (XCP) and the
Rate Control Protocol (RCP) are the prominent clean slate congestion
control protocols. Nonetheless, the XCP protocol is also proved to
have its own performance problems some of which are its unfairness
to long flows (flows with high round trip delay), and many per-packet
computations at the router. As shown in this paper RCP also makes
gross approximation to its important component that it may only give
the performance reports shown in the literature for specific choices of
its parameter values and traffic patterns.
In this paper we present a new congestion control protocol called
Network congestion Control Protocol (NCP). We show that NCP can
outperform both TCP, XCP and RCP in terms of among other things
fairness and file download times.unpublishe
Full duplex switched ethernet for next generation "1553B" -based applications
Over the last thirty years, the MIL-STD 1553B data bus has been used in many embedded systems, like aircrafts, ships, missiles and satellites. However, the increasing number and complexity of interconnected subsystems lead to emerging needs for more communication bandwidth. Therefore, a new interconnection system is needed to overcome the limitations of the MIL-STD 1553B data bus. Among several high speed networks, Full Duplex Switched Ethernet is put forward here as an attractive candidate to replace the MIL-STD 1553B data bus. However, the key argument against Switched Ethernet lies in its non-deterministic behavior that makes it inadequate to deliver hard timeconstrained communications. Hence, our primary objective in this paper is to achieve an accepted QoS level offered by Switched Ethernet, to support diverse "1553B"-based applications requirements. We evaluate the performance of traffic shaping techniques on Full Duplex Switched Ethernet with an adequate choice of service strategy in the switch, to guarantee the real-time constraints required by these specific 1553B-based applications. An analytic study is conducted, using the Network Calculus formalism, to evaluate the deterministic guarantees offered by our approach. Theoretical analysis are then investigated in the case of a realistic "1553B"-based application extracted from a real military aircraft network. The results herein show the ability of profiled Full Duplex Switched Ethernet to satisfy 1553B-like real-time constraints
An efficient hybrid model and dynamic performance analysis for multihop wireless networks
Multihop wireless networks can be subjected to nonstationary phenomena due to a dynamic network topology and time varying traffic. However, the simulation techniques used to study multihop wireless networks focus on the steady-state performance even though transient or nonstationary periods will often occur. Moreover, the majority of the simulators suffer from poor scalability. In this paper, we develop an efficient performance modeling technique for analyzing the time varying queueing behavior of multihop wireless networks. The one-hop packet transmission (service) time is assumed to be deterministic, which could be achieved by contention-free transmission, or approximated in sparse or lightly loaded multihop wireless networks. Our model is a hybrid of time varying adjacency matrix and fluid flow based differential equations, which represent dynamic topology changes and nonstationary network queues, respectively. Numerical experiments show that the hybrid fluid based model can provide reasonably accurate results much more efficiently than standard simulators. Also an example application of the modeling technique is given showing the nonstationary network performance as a function of node mobility, traffic load and wireless link quality. © 2013 IEEE
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