475 research outputs found
Homa: A Receiver-Driven Low-Latency Transport Protocol Using Network Priorities (Complete Version)
Homa is a new transport protocol for datacenter networks. It provides
exceptionally low latency, especially for workloads with a high volume of very
short messages, and it also supports large messages and high network
utilization. Homa uses in-network priority queues to ensure low latency for
short messages; priority allocation is managed dynamically by each receiver and
integrated with a receiver-driven flow control mechanism. Homa also uses
controlled overcommitment of receiver downlinks to ensure efficient bandwidth
utilization at high load. Our implementation of Homa delivers 99th percentile
round-trip times less than 15{\mu}s for short messages on a 10 Gbps network
running at 80% load. These latencies are almost 100x lower than the best
published measurements of an implementation. In simulations, Homa's latency is
roughly equal to pFabric and significantly better than pHost, PIAS, and NDP for
almost all message sizes and workloads. Homa can also sustain higher network
loads than pFabric, pHost, or PIAS.Comment: This paper is an extended version of the paper on Homa that was
published in ACM SIGCOMM 2018. Material had to be removed from Sections 5.1
and 5.2 to meet the SIGCOMM page restrictions; this version restores the
missing material. This paper is 18 pages, plus two pages of reference
Adaptive Allocation of Decision Making Responsibility Between Human and Computer in Multi-Task Situations
A unified formulation of computer-aided, multi-task, decision making is presented. Strategy for the allocation of decision making responsibility between human and computer is developed. The plans of a flight management systems are studied. A model based on the queueing theory was implemented
Efficient Resource Management Mechanism for 802.16 Wireless Networks Based on Weighted Fair Queuing
Wireless Networking continues on its path of being one of the most commonly used means of communication. The evolution of this technology has taken place through the design of various protocols. Some common wireless protocols are the WLAN, 802.16 or WiMAX, and the emerging 802.20, which specializes in high speed vehicular networks, taking the concept from 802.16 to higher levels of performance. As with any large network, congestion becomes an important issue. Congestion gains importance as more hosts join a wireless network. In most cases, congestion is caused by the lack of an efficient mechanism to deal with exponential increases in host devices. This can effectively lead to very huge bottlenecks in the network causing slow sluggish performance, which may eventually reduce the speed of the network. With continuous advancement being the trend in this technology, the proposal of an efficient scheme for wireless resource allocation is an important solution to the problem of congestion. The primary area of focus will be the emerging standard for wireless networks, the 802.16 or âWiMAXâ. This project, attempts to propose a mechanism for an effective resource management mechanism between subscriber stations and the corresponding base station
Performance Modelling and Resource Allocation of the Emerging Network Architectures for Future Internet
With the rapid development of information and communications technologies, the traditional network architecture has approached to its performance limit, and thus is unable to meet the requirements of various resource-hungry applications. Significant infrastructure improvements to the network domain are urgently needed to guarantee the continuous network evolution and innovation. To address this important challenge, tremendous research efforts have been made to foster the evolution to Future Internet. Long-term Evolution Advanced (LTE-A), Software Defined Networking (SDN) and Network Function Virtualisation (NFV) have been proposed as the key promising network architectures for Future Internet and attract significant attentions in the network and telecom community. This research mainly focuses on the performance modelling and resource allocations of these three architectures. The major contributions are three-fold:
1) LTE-A has been proposed by the 3rd Generation Partnership Project (3GPP) as a promising candidate for the evolution of LTE wireless communication. One of the major features of LTE-A is the concept of Carrier Aggregation (CA). CA enables the network operators to exploit the fragmented spectrum and increase the peak transmission data rate, however, this technical innovation introduces serious unbalanced loads among in the radio resource allocation of LTE-A. To alleviate this problem, a novel QoS-aware resource allocation scheme, termed as Cross-CC User Migration (CUM) scheme, is proposed in this research to support real-time services, taking into consideration the system throughput, user fairness and QoS constraints.
2) SDN is an emerging technology towards next-generation Internet. In order to improve the performance of the SDN network, a preemption-based packet-scheduling scheme is firstly proposed in this research to improve the global fairness and reduce the packet loss rate in SDN data plane. Furthermore, in order to achieve a comprehensive and deeper understanding of the performance behaviour of SDN network, this work develops two analytical models to investigate the performance of SDN in the presence of Poisson Process and Markov Modulated Poisson Process (MMPP) respectively.
3) NFV is regarded as a disruptive technology for telecommunication service providers to reduce the Capital Expenditure (CAPEX) and Operational Expenditure (OPEX) through decoupling individual network functions from the underlying hardware devices. While NFV faces a significant challenging problem of Service-Level-Agreement (SLA) guarantee during service provisioning. In order to bridge this gap, a novel comprehensive analytical model based on stochastic network calculus is proposed in this research to investigate end-to-end performance of NFV network.
The resource allocation strategies proposed in this study significantly improve the network performance in terms of packet loss probability, global allocation fairness and throughput per user in LTE-A and SDN networks; the analytical models designed in this study can accurately predict the network performances of SDN and NFV networks. Both theoretical analysis and simulation experiments are conducted to demonstrate the effectiveness of the proposed algorithms and the accuracy of the designed models. In addition, the models are used as practical and cost-effective tools to pinpoint the performance bottlenecks of SDN and NFV networks under various network conditions
Squeaky Wheel Optimization
We describe a general approach to optimization which we term `Squeaky Wheel'
Optimization (SWO). In SWO, a greedy algorithm is used to construct a solution
which is then analyzed to find the trouble spots, i.e., those elements, that,
if improved, are likely to improve the objective function score. The results of
the analysis are used to generate new priorities that determine the order in
which the greedy algorithm constructs the next solution. This
Construct/Analyze/Prioritize cycle continues until some limit is reached, or an
acceptable solution is found. SWO can be viewed as operating on two search
spaces: solutions and prioritizations. Successive solutions are only indirectly
related, via the re-prioritization that results from analyzing the prior
solution. Similarly, successive prioritizations are generated by constructing
and analyzing solutions. This `coupled search' has some interesting properties,
which we discuss. We report encouraging experimental results on two domains,
scheduling problems that arise in fiber-optic cable manufacturing, and graph
coloring problems. The fact that these domains are very different supports our
claim that SWO is a general technique for optimization
VSRS: Variable Service Rate Scheduler for Low Rate Wireless Sensor Networks
This paper proposes a variable service rate scheduler VSRS for heterogeneous wireless sensor and actuator networks (WSANs). Due to recent advancement, various applications are being upgraded using sensor networks. Generally, traffic consists of delay sensitive and delay tolerant applications. Handling such traffic simultaneously is a critical challenge in IEEE 802.15.4 sensor network. However, the standard CSMA/CA does not focus on traffic-based data delivery. Therefore, this paper presents a solution for prioritybased traffic over no-priority i.e. regular traffic using CSMA/CA IEEE 802.15.4 MAC sublayer. The VSRS scheduler uses a queuing model for scheduling incoming traffic at an actor node using a dual queue. The scheduler updates priority of each incoming packet dynamically using network priority weight metric. The VSRS scheduler scans queues and picks the highest network priority packet. A packet weight is updated after selection from the respective queue. This core operation of an actor node offers good packet delivery ratio, throughput, and less delay experience of long distance traveled packets against no priority traffic. The work is validated using theoretical analysis and computer generated network simulators; proves that the priority based approach using weight factor works better over the First-Come-First-Serve (FCFS) mechanism
A Survey of Quality of Service Differentiation Mechanisms for Optical Burst Switching Networks
Cataloged from PDF version of article.This paper presents an overview of Quality of Service (QoS) differentiation mechanisms
proposed for Optical Burst Switching (OBS) networks. OBS has been proposed to couple
the benefits of both circuit and packet switching for the ââon demandââ use of capacity in
the future optical Internet. In such a case, QoS support imposes some important challenges
before this technology is deployed. This paper takes a broader view on QoS, including QoS
differentiation not only at the burst but also at the transport levels for OBS networks.
A classification of existing QoS differentiation mechanisms for OBS is given and their
efficiency and complexity are comparatively discussed. We provide numerical examples
on how QoS differentiation with respect to burst loss rate and transport layer throughput
can be achieved in OBS networks.
© 2009 Elsevier B.V. All rights reserved
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