Data/voice integration for fibre optic LANs with arbitrary topology

A high-performance protocol for arbitrary point-to-point fibre optic local area networks with combined voice and data traffic is described. Simulation on a 3 Mbit/s nine-node mesh network has shown that it is capable of supporting a substantial number of data users and more than 100 active voice calls (200 active telephone users, coding rate 64 kbit/s without silence detection) with a packet delay of less than 10 ms and without any loss of information. The network performance is superior to the previous reported voice protocol which used the modified anarchy flood routing (MAFR) technique. Performance limitation due to growing network size for flood-routed networks is also discussed. A method of extending the flood-routing protocols over subnetworks which are connected via bridges is also presented. This method enables a large network to be divided into smaller subnetworks which reduces the number of links required.     

An X.25-compatible protocol for packet voice communications

Developments in packet-switched networks have generated interest in how to integrate voice and data traffic in such networks. The paper deals with a proposed communications protocol for voice transmission within X.25 packet-switched networks. Basic protocol procedures for handling voice communications are examined, and possible formats for the identified types of voice frame and packet fitting for current CCITT standards governing packet data communications are presented.     

Design issues for a fibre optic local network

Ermes is a joint project of the Commission of the European Communities and the Institute of Cybernetics involving the implementation of a dedicated local network for real-time applications based on a wide-band fibre-optic transmission medium. The network uses the nucleus of a distributed operating system that implements a message-exchange mechanism but can be extended to represent the runtime support of a distributed programming language. The paper discusses the design issues affecting the software architecture and the hardware configuration, and describes the current implementation in detail, including software aspects and the physical layer.     

Twin-bus-controller protocol for fibre optic networks

A new Data Link Layer protocol, named the Twin-Bus-Controller (TBC) protocol, is proposed for a fibre optic network with unidirectional bus topology. The TBC protocol operates on a contention-based, time-division multiplexing scheme, and is managed by two centralized bus controllers. These controllers, which also function as network managers cooperate with each other to control and coordinate the activities on the twin bus. The IBC protocol has the capability to perform at a very high network utilization, and uses simple hardware at all stations except the two bus controllers. This arrangement provides a relatively inexpensive means to accommodate a large number of stations. Heterogeneous data consisting of real-time sensor and control signals, voice and video data, and non-real-time data such as those due to accounting and administration, can be simultaneously handled by the TBC protocol. The TBC protocol maintains global queues for all different types of data, and each class of data has a bounded delay. Furthermore, any new type of data can be added easily to the network without shutting it down or affecting those stations that are unrelated to the new data. A finite-state-machine model has been used to describe the TBC protocol. Performance of the TBC protocol has been evaluated by statistical analysis as well as via simulation for multiple classes of data traffic. Performance of the TBC protocol has been compared with that of Buzznet and Fasnet. The TBC protocol can be directly applied to diverse computer communication systems, e.g. office, manufacturing, and banking environments.     

A wireless sensor networks MAC protocol for real-time applications

Wireless sensor networks (WSN) are designed for data gathering and processing, with particular requirements: low hardware complexity, low energy consumption, special traffic pattern support, scalability, and in some cases, real-time operation. In this paper we present the virtual TDMA for sensors (VTS) MAC protocol, which intends to support the previous features, focusing particularly on real-time operation. VTS adaptively creates a TDMA arrangement with a number of timeslots equal to the actual number of nodes in range. Thus, VTS achieves an optimal throughput performance compared to TDMA protocols with fixed size of frame. The frame is set up and maintained by a distributed procedure, which allows sensors to asynchronously join and leave the frame. In addition, duty cycle is increased or decreased in order to keep latency constant below a given deadline. Therefore, a major advantage of VTS is that it guarantees a bounded latency, which allows soft real-time applications.

Building local area networks to Ethernet specification

Digital, Intel and Xerox (DIX) have published an Ethernet standard that specifies the physical and datalink layers of Ethernet, one of the two types of local area networks likely to be widely used in industrial and commerical applications. The publication of the DIX specification is a commercial exercise intended to encourage the implementation and marketing of Ethernet-compatible network elements. In the Computer Science Department at Strathclyde University the authors followed this specification to some extent in implementing an Ethernet-style local network called Strathnet. In their implementation, the physical and datalink layers are built into microprocessor-based network-access units by means of which computers, terminals and other devices are connected to Strathnet. The paper discusses the feasibility and desirability of building local networks to the standards of the Ethernet specification and in the light of this discussion outlines the author's approach in the implementation of Strathnet.     

Buffer analysis of an integrated voice and data terminal

Current research activities in computer networks tend to emphasize the integration of services such as voice and data by designing networks that take into account the performance requirements of these services. In some cases, however, design and implementation of a totally new network may not be feasible. An alternative approach in such cases would be to integrate the services at the terminal level. Such an integrated terminal could also be widely used in future office automation systems. The performance of such an integrated terminal is assessed with the assumption that the terminal is connected to a voiceband channel. The analysis indicates the performance limits on the application imposed by the buffer size at the terminal and the large fluctuation of delay performance for data traffic. A window-type flow control for data traffic is also considered. By appropriately choosing the buffers in the terminal and window size, both voice and data traffic service requirements can be met.     

Banet — a local area network for distributed data processing

A broadcast architecture network (Banet) suitable for distributed data processing is proposed. One feature of Banet is that the broadcast-within-a-group function is supported not only by the datalink level but by the transport or session-level network structure. The commitment control scheme is included in the network protocol. Design goals, physical structure and protocols are discussed.     

多跳Ad Hoc网络基于路由协议的拥塞控制

为解决Ad Hoc网络的DSR路由协议在通信过程中存在拥塞问题,提出了改进DSR路由协议的思想,即联合“最短路径”和节点发送接收数据包时的“传输状态”来避免拥塞。仿真结果表明,改进后的路由协议有效地减少了发生拥塞的几率,从而提高了无线多跳Ad Hoc网络环境下Web通信的性能。     

Managing local area networks

This paper considers the need to provide some form of local area network management. Although Ethernet systems form the main example, the requirements are the same, in general, for other local networks. The authors argue why network management is necessary, examine the difficulties involved, and take a look at the current standards work in the area. Finally, they discuss management of their own particular local area network environment.     

Congestion control technique for an integrated services local area network

A congestion control scheme for implementation in an integrated services local area network is proposed. An outline is given of simulation studies that have been carried out to demonstrate the feasibility and effectiveness of such a scheme. The way that these studies can help identify the volume of real-time traffic that can be accommodated with an acceptable level of blocking is explained.     

A quality based routing protocol for wireless mesh networks

Wireless mesh networks can provide low-cost solutions for extending the reach of wireless access points by using multi-hop routing over a set of stationary wireless routers. The routing protocol for these networks may need to address quality considerations to meet the requirements of the user. In this paper, we present a quality based routing protocol for wireless mesh networks that tries to maximize the probability of successful transmissions while minimizing the end-to-end delay. The proposed routing protocol uses reactive route discoveries to collect key parameters from candidate routes to estimate the probability of success and delay of data packets transmitted over them. To achieve accurate route quality assessments, a new route quality metric is proposed that uses performance models of data packet transmissions as opposed to estimating route quality from the transmission of control packets, which have different transmission characteristics. These models are developed after careful evaluations of multi-hop wireless transmissions and validated by computer simulations. Relevant parameters that can be used to assess the route quality metric using these models are explained. Extensive performance evaluations of the proposed quality based routing protocol are presented and its benefits in comparison to some other known routing protocols are discussed.     

Swarm intelligence based routing protocol for wireless sensor networks: Survey and future directions

Swarm intelligence is a relatively novel field. It addresses the study of the collective behaviors of systems made by many components that coordinate using decentralized controls and self-organization. A large part of the research in swarm intelligence has focused on the reverse engineering and the adaptation of collective behaviors observed in natural systems with the aim of designing effective algorithms for distributed optimization. These algorithms, like their natural systems of inspiration, show the desirable properties of being adaptive, scalable, and robust. These are key properties in the context of network routing, and in particular of routing in wireless sensor networks. Therefore, in the last decade, a number of routing protocols for wireless sensor networks have been developed according to the principles of swarm intelligence, and, in particular, taking inspiration from the foraging behaviors of ant and bee colonies. In this paper, we provide an extensive survey of these protocols. We discuss the general principles of swarm intelligence and of its application to routing. We also introduce a novel taxonomy for routing protocols in wireless sensor networks and use it to classify the surveyed protocols. We conclude the paper with a critical analysis of the status of the field, pointing out a number of fundamental issues related to the (mis) use of scientific methodology and evaluation procedures, and we identify some future research directions.     

移动Ad Hoc网络基于路由协议的拥塞控制

为解决Ad Hoc网络的AODV路由协议在通信过程中存在的拥塞问题,提出了改进AODV路由协议的思想。根据网络链路拥塞度的大小采取不同措施和节点路由,建立不相关多径路由分流以避免拥塞。仿真结果表明,改进后的路由协议有效地减少了发生拥塞的几率,从而提高了移动Ad Hoc网络的性能。     

Design of integrated data/voice stations for a CSMA/CD LAN

This paper describes the design and implementation of integrated data/voice stations for a LAN environment. The stations are based on the DB16000 Development Board using a 16-bit CPU. Continuously variable slope delta modulation is selected as the voice encoding technique. Protocols were designed and implemented to handle data and voice separately. Prototypes were built to test the station's performance. The stations communicate with one another at a rate of 1.5 Mbit/s. The voice digitization rate is 16 kbit/s and the terminal speed is 9.6 kbit/s.     

New technologies and their implications for local area networks

The impact on local area networking of recent technological developments is discussed. Such technologies include: artificial intelligence, optical storage systems, video telephone and personal identification equipment. The paper also looks at four carrier services: cable television, British Telecom's IDA system, value added networks and public information networks and assesses the influence these will have on local area networks.     

一个低开销的无线传感器网络多径路由协议

针对多对一的周期性数据收集应用,提出一个低开销的逐跳多径路由协议LOMP,综合利用定期和实时估计器评估链路质量,在此基础上实现高质量的多径路由。与现有的多径路由协议相比,LOMP并不提供端到端的节点独立的多径路由,而只是确保在报文的每一跳转发过程中都有多条路径可用。仿真结果表明LOMP能够提高选路质量,以较小的能量开销提高数据传输的可靠性。     

一种基于节点密度的无线传感器网络路由协议

能量问题一直是制约无线传感器网络(WSNs)发展的问题。成簇算法可以很好地降低网络通信能耗。分析已有的各类成簇算法,在LEACH协议的基础上,改进了簇头节点的选取方式。讨论了网内簇头个数的选择,然后以网内节点密度为参考选取簇头,通过赋予不同的参数来比较节点密度对协议运行的影响。仿真结果表明:改进的算法有效降低了通信能耗,延长了网络的生存周期。     

用于工业监测的无线传感器网络多径路由协议

针对工业监测中多对一周期性数据采集应用,提出一个高可靠低开销逐跳多径路由协议PHMP.根据应用特点,综合利用定期和实时估计器评估链路质量,提高了选路质量.设计了一种高可靠低开销的逐跳多径路由,而且选路时还考虑了网络节点能耗的均衡性.仿真结果表明,PHMP能提高选路质量,以较小的能量和存储开销提高传输的可靠性,并且可提高网络节点能耗均衡性,从而尽可能地延长网络生存时间.