A protocol structure for high-speed communication over broadbandISDN

Various possibilities for improving the performance of communications protocols and interfaces so that the slow-software-fast-transmission bottleneck can be alleviated are investigated. An architecture that is an alternative to the existing layered architectures is proposed. The novel feature of the proposed architecture is the reduction in the vertical layering; services that correspond to the definitions of layers four to six in the Open Systems Interconnection Reference Model are combined into a single, horizontally structured layer. This approach lends itself more naturally to parallel implementation. Moreover, the delay of a set of processes implemented in parallel is determined by the delay of the longest process, not by the sum of all the process delays, as is the case in a sequential implementation. In the same way, the total throughput need not be limited by the lowest-capacity process, but can be increased by concurrently performing the function on several devices     

Design and implementation of a high-speed transport protocol

The design, analysis, and implementation of an end-to-end transport protocol that is capable of high throughput consistent with the evolving high-speed physical networks based on fiber-optic transmission lines and high-capacity switches are presented. Unlike current transport protocols in which changes in control/state information are exchanged between the two communicating entities only when some significant event occurs, this protocol exchanges relevant and full state information periodically and frequently. It is shown that this reduces the complexity of protocol processing by removing many of the procedures required to recover from network inadequacies such as bit errors, packet loss, and out-of-sequence packets and makes it more amenable to parallel processing. Also, to increase channel utilization in the presence of high-speed, long-latency networks and to support diagrams, and efficient implementation of the selective repeat method of error control is incorporated in the protocol. An implementation using a Motorola 68030-based multiprocessor as a front-end processor is described. The current implementation can comfortably handle 10-15 kpackets/s     

Implementing scheduling algorithms in high-speed networks

The fluid generalized processor sharing (GPS) algorithm has desirable properties for integrated services networks and many packet fair queueing (PFQ) algorithms have been proposed to approximate GPS. However, there have been few high-speed implementations of PFQ algorithms that can support a large number of sessions with diverse rate requirements and at the same time maintain all the important properties of GPS. The implementation cost of a PFQ algorithm is determined by: (1) computation of the system virtual time function; (2) maintenance of the relative ordering of the packets via their timestamps (scheduling); and (3) regulation of packets based on eligibility time, in some algorithms. While most of the recently proposed PFQ algorithms reduce the complexity of computing the system virtual time function, the complexity of scheduling and traffic regulation is still a function of the number of active sessions. In addition, while reducing the algorithmic or asymptotic complexity has been the focus of most analysis, it is also important to reduce the complexity of basic operations in order for the algorithm to run at high speed. We develop techniques to reduce both types of complexities for networks of both fixed and variable size packets. Regulation and scheduling are implemented in an integrated architecture that can be viewed as logically performing sorting in two dimensions simultaneously. By using a novel grouping architecture, we are able to perform this with an algorithmic complexity independent of the number of sessions in the system at the cost of a small controllable amount of relative error. To reduce the cost of basic operations, we propose a hardware-implementation framework and several novel techniques that reduce the on-chip memory size, off-chip memory bandwidth, and off-chip access latency. The proposed implementation techniques have been incorporated into commercial ATM switch and IP router products     

The MultiStream protocol: a highly flexible high-speed transportprotocol

A transport layer protocol designed to meet the wide-ranging needs of high-speed applications is described. A unique feature of this protocol is that its behavior, defined by a set of functions, may be modified dynamically over the life of a connection without loss of reliable data transfer. This property makes the protocol attractive for supporting applications, such as multimedia applications that require different protocol support for different portions of their traffic streams. The protocol has been verified to reliably deliver data and manage connections and to contain no deadlocks or loops. A parallel architecture for implementing the protocol has also been verified. Analysis of a skeleton implementation shows that the protocol has the potential to receive data at a rate of over 150 kpackets/s if 10-MIPS processors are used in the implementation     

Sizing a packet reassembly buffer at a host computer in an ATMnetwork

This paper develops a queueing model of a buffer that collects cells for reassembly into packets for a protocol layer above the asynchronous transfer mode (ATM) layer. Whenever the buffer fills with all packets incomplete, a packet must be sacrificed to make room for others. The queueing model estimates the equilibrium fraction of packets sacrificed under one algorithm for selecting the packet to be sacrificed. The paper also uses simulation to compare three sacrifice algorithms. The model's predicted packet loss probabilities bound from above the loss probabilities in the simulations of the different algorithms. Applications to sizing the buffer for a prescribed loss probability are given     

Specification and analysis of the SNR high-speed transport protocol

The emergence of optical fiber and its correspondingly high data rates have led to the development of much higher speed networks, both locally and over the long haul. These developments led to the design of new transport protocols, which were intended to take advantage of the high-speed networks. A number of these so-called “high-speed transport protocols” have been designed to date. This paper considers one of these, called the SNR protocol, in detail. A formal specification of the protocol is presented, using the protocol model systems of communicating machines, and the protocol is then analyzed through the specification. An implementation of the protocol based on this formal definition has also been made, and used to simulate the protocol, providing further insights into its performance. Based on the combined results of the analysis and the simulated protocol, a high degree of confidence is gained in the correctness of the protocol. The specification is quite detailed, and from it an implementation should be fairly straightforward. The paper also discusses the difficulties encountered during the analysis of such a complex protocol, and suggests some possible solutions to these problems. Finally, as a result of this work, we comment on the strengths and weakness of the SNR protocol as a solution to the high-speed transport protocol problem, and make two simple suggestions for improving it     

Implementing a secure VoIP communication over SIP-based networks

Recent years the Session Initiation Protocol (SIP) is commonly used in establishing Voice over IP (VoIP) calls and has become the centerpiece for most VoIP architecture. As wireless and mobile all-IP networks become prosperous, free VoIP applications are utilized in all places. Consequently, the security VoIP is a crucial requirements for its adoption. Many authentication and key agreement schemes are proposed to protect the SIP messages, however, lacking concrete implementations. The performance of VoIP is critical for users’ impressions. In view of this, this paper studies the performance impact of using key agreements, elliptic curve Diffie–Hellman and elliptic curve Menezes–Qu–Vanstone, for making a SIP-based VoIP call. We evaluate the key agreement cost using spongycastle.jce.provider package in Java running on android-based mobile phones, the effect of using different elliptic curves and analyze the security of both key agreements. Furthermore, we design a practical and efficient authentication mechanism to deploy our VoIP architecture and show that a VoIP call can be established in an acceptable interval. As a result, this paper provides a concrete and feasible architecture to secure a VoIP call.     

An efficient communication protocol for high-speed packet-switchedmultichannel networks

A media-access protocol for high-speed packet-switched multichannel networks that are based on a broadcast topology, such as optical passive star networks using wavelength-division multiple access, is described. The protocol supports connection-oriented traffic with or without bandwidth reservation, as well as datagram traffic to integrate transport-layer functions with the media-access layer. It uses the bandwidth efficiently while keeping the processing requirements low by requiring stations to compute their transmission and reception schedules only at the start and end of each connection. Analysis results show that low blocking probabilities for connections and high network throughput can be achieved     

航空高速总线协议AS5643的FPGA实现

介绍并分析了拥有高确定性和可靠性的AS5643总线协议。为了将处理器从繁杂的协议中解脱出来,提出了基于FPGA的AS5643协议实现方案,详细介绍了协议模块的系统设计及VHDL语言实现。实验证明该协议模块符合AS5643协议规范,该设计可应用于对总线性能要求较高的综合化航空电子系统中。     

Modbus RTU通信协议在MCF51QE128上的实现

Modbus串行通信协议是一种主从协议.其开放性使其成为广泛应用在工业制造环境中的一种网络协议.本文通过列Modbus协议的介绍,详细介绍了它在飞思卡尔的MCF51QE128微控制器上的具体实现     

Improvement on a privacy-preserving outsourced classification protocol over encrypted data

Wireless Networks - In outsourced classification services, classifier owners outsource their classifiers to remote servers due to resource constraints, and users can request classification services...     

基于FPGA的高速同步HDLC通信控制器设计

高级数据链路控制HDLC协议是一种面向比特的链路层协议,具有同步传输数据、冗余度低等特点,是在通信领域中应用最广泛的链路层协议之一.提出实现HDLC通信协议的主要模块-CRC校验模块及'0'比特插入模块的FPGA实现方法.CRC校验模块采用状态机设计方法,而'0'比特插入模块是利用FIFO实现,为HDLC通信控制器的设计提供新的思路.该方法已在Spartan3s400开发板上实现,并能正确传输.     

A flexible MAC protocol for the integration of high- and low-quality video streams, voice and data traffic over high-speed packet switched wireless networks

In this work, we propose and evaluate mechanisms for the multiplexing and the integrated delivery of various traffic types such as video, data and voice, over a wireless cellular high-speed packet switched network. Two different scenarios are examined where the video traffic results from videoconference sessions and high-quality media playback, respectively. In both cases we focus on the uplink channel and we thoroughly investigate, by using actual MPEG-4 video streams, the system's performance under a variety of possible loads. Our goal is to achieve high-aggregate channel throughput while preserving the quality of service requirements of each traffic type.     

利用有线电视光纤网络实现新闻节

本文介绍和探讨了数字、模拟、基带三种传输体制的优缺点,并从我市的网络结构和实际状况出发,确立了应用基带传输体制构建我市的新闻回传系统.在此基础上,重点阐述了基带(视、音频)PFM的传输原理和整个回传系统的指标分析、系统结构、设备选型配置、系统测试、操作维护、系统评价等内容.     

Voice over Internet protocol (VoIP)

During the Internet stock bubble, articles in the trade press frequently said that, in the near future, telephone traffic would be just another application running over the Internet. Such statements gloss over many engineering details that preclude voice from being just another Internet application. This paper deals with the technical aspects of implementing voice over Internet protocol (VoIP), without speculating on the timetable for convergence. First, the paper discusses the factors involved in making a high-quality VoIP call and the engineering tradeoffs that must be made between delay and the efficient use of bandwidth. After a discussion of codec selection and the delay budget, there is a discussion of various techniques to achieve network quality of service. Since call setup is very important, the paper next gives an overview of several VoIP call signaling protocols, including H.323, SIP, MGCP, and Megaco/H.248. There is a section on telephony routing over IP (TRIP). Finally, the paper explains some VoIP issues with network address translation and firewalls     

基于Interlaken协议的高速数据流接口设计与性能分析

目前,高速网络处理系统的板级互连带宽达到了40G比特速率级,这对网络处理系统的处理速度和吞吐量提出了极大的挑战。为解决核心路由器40 Gb/sPOS线路接口板中器件间的高速数据交互难题,采用Interlaken协议对高速数据流接口设计方法进行了研究,利用高端FPGA的高速通道和IP核设计技术,完成了链路层处理芯片与转发...     

Optimal design of a high-speed polymer Mach-Zehnder interferometer electro-optic switch over 260 GHz

By using the proposed 3-D mode propagation analysis method and point-matching method, a polymer multimode interference (MMI) Mach-Zehnder interferometer (MZI) electro-optic (EO) switch is designed and optimized for enhancing the EO modulating efficiency and matching the impedance and the velocity. The designed switch possesses low driving voltages of ±1.375 V with a short EO active region length of 5 mm under 1550 nm wavelength, and the estimated cutoff switching frequency is up to 263 GHz due to the less mismatch between the lightwave velocity and microwave velocity. The 3-dB lightwave bandwidth is 60 nm, and within the wavelength range of 1520–1580 nm, the insertion loss and crosstalk are less than 6.71 and −30 dB, respectively.     

RQRP protocol for video delivery over IP

The Digital Audio‐Visual Council has adopted the Request/Reply (RQRP) protocol, proposed by one of the authors, for the delivery mechanism of MPEG video streams. In this paper, we investigate the network characteristics of the RQRP protocol and analyse the protocol's performance via both simulation as well as actual experimental results. In this simulation, the RQRP protocol was mathematically an ideal model first and later, a feedback control system. Simulation results showed that, for both models, the network traffic is able to follow the playout rate at the receiver. In the case of the latter, which involves a simpler implementation, oscillation in network traffic is observed. A video‐on‐demand (VoD) system using the RQRP protocol was developed and experiments were performed. The results obtained are consistent with the simulation results. Copyright © 2001 John Wiley & Sons, Ltd.     

Voice over Internet protocol and human-assisted e-commerce

By fostering the finalization of open standards and the convergence of voice, video, and data, the Internet protocol provides an ideal driver for the definition of the infrastructure for new multimedia and advanced communications applications. Voice over IP represents not only the chance to achieve cost-effective real-time voice communication over IP-based networks, but also the opportunity to build an integrated and open communications service delivery infrastructure. Developments of Web-based information systems and IP telephony in order to enable future e-commerce applications are summarized     

Smartphones Apps Implementing a Heuristic Joint Coding for Video Transmissions over Mobile Networks

This paper presents the scheme Heuristic Application Layer Joint Coding (Heuristic-ALJC) for video transmissions aimed at adaptively and jointly varying both applied video compression and source encoding at the application layer used to protect video streams. Heuristic-ALJC includes also a simple acknowledgement based adaptation of the transmission rate and acts on the basis of feedback information about the overall network status estimated in terms of maximum allowable network throughput and link quality (lossiness). Heuristic-ALJC is implemented through two smartphone Apps (transmitter and receiver) and is suitable to be employed to transmit video streams over networks based on time varying and possibly lossy channels. A deep performance investigation, carried out through a real implementation of the Apps over Android smartphones, compares Heuristic-ALJC with static schemes.