Showing papers on "Broadband networks published in 1990"

Fast packet switch architectures for broadband integrated services digital networks

Abstract: Background information on networking and switching is provided, and the various architectures that have been considered for fast packet switches are described. The focus is solely on switches designed to be implemented electronically. A set of definitions and a brief description of the functionality required of fast packet switches are given. Three basic types of packet switches are identified: the shared-memory, shared-medium, and space-division types. Each of these is described, and examples are given. >

Switching and Traffic Theory for Integrated Broadband Networks

Abstract: 1. Integrated Broadband Services and Networks-An Introduction.- I: SWITCHING THEORY.- 2. Broadband Integrated Access and Multiplexing.- 3. Point-to-Point Multi-Stage Circuit Switching.- 4. Multi-Point and Generalized Circuit Switching.- 5. From Multi-Rate Circuit Switching to Fast Packet Switching.- 6. Applying Sorting for Self-Routing and Non-Blocking Switches.- II: TRAFFIC THEORY.- 7. Terminal and Aggregate Traffic.- 8. Blocking for Single-Stage Resource Sharing.- 9. Blocking for Multi-Stage Resource Sharing.- 10. Queueing for Single-Stage Packet Networks.- 11. Queueing for Multi-Stage Packet Networks.

Cellular packet communications

Abstract: The future of third-generation wireless networking is discussed. The vision of the third generation is a single set of standards that can meet a wide range of wireless access applications. Third-generation systems, in harmony with broadband integrated services digital networks, will use shared resources to convey many information types. A single network architecture will serve its users efficiently in many environments, including moving vehicles, indoor and outdoor public areas, residences, offices, and factories. A study of a switching architecture, referred to as a cellular packet switch, and a packet transmission technique, referred to as a packet reservation multiple access is discussed. By means of a design example, it is shown how these techniques can work together to meet some of the demands of third-generation systems. >

Reliable broadband communication using a burst erasure correcting code

Abstract: Traditionally, a transport protocol corrects errors in a computer communication network using a simple ARQ protocol. With the arrival of broadband networks, forward error correction is desirable as a complement to ARQ. This paper describes a simplified Reed-Solomon erasure correction coder architecture, adapted for congestion loss in a broadband network. Simulations predict it can both encode and decode at rates up to 1 gigabit per second in a custom 1 micron CMOS VLSI chip.

Broad-band ATM network architecture based on virtual paths

Abstract: Broadband transport techniques and network architectures based on the virtual path concept are examined. ATM (asynchronous transfer mode) techniques, when coupled with recent technological innovations, are expected to pave the way for future universal transport networks. The virtual path concept, which exploits the ATM's capabilities, is proposed to construct an efficient and economic network. The concept matches current and anticipated technological trends well. Characteristics and implementation techniques of virtual paths are discussed. Advantages of the virtual path concept and its impact on the transport network architecture are demonstrated. The virtual path strategy is also shown to provide efficiently for networks with dynamic reconfiguration capability which will enhance network performance. Some basic analytical results on the dynamic control effects of virtual paths are provided. >

Sunshine: a high performance self-routing broadband packet switch architecture

Abstract: The fiber based broadband network will offer services ranging from circuit emulations where extremely low cell loss rams are essential to high speed variable rate services which can tolerate a degree of cell loss but whose bandwidth requirements may be extremely bursty and unpredictable. This paper presents a high performance self-routing packet switch architecture called Sunshine, that is well suited for this wide range of potential services with their diverse performance objectives and traffic characteristics. Sunshine is based on Batcher/banyan networks and combines both internal and output queuing techniques within a single architecture. Access to the output queues is provided by parallel banyan routing networks which allow multiple cells to be delivered simultaneously to each destination. Excess cells, due to momentary output overloads, overflow into a shared recirculating queue where they are delayed and resubmited as dedicated switch inputs in the following packet slot. A priority structure ensures cefts access each queue based on priority allowing multiple grades of service to coexist within the switch. Results based on extensive simulations which modeled low speed services by a random arrival process, circuit emulations by a periodic arrival process, and high speed variable-rate services by a bursty process show that this architecture can achieve the extremely low cell loss rates necessary for circuit emulations, and is robust in a bursty environment.

Comparative performance study of space priority mechanisms for ATM networks

Abstract: Priorities for buffer access, also called space priorities, are discussed in connection with the asynchronous transfer mode (ATM), which is widely accepted as the basis for the future broadband ISDN. The introduction of priorities enables the ATM layer to adapt the quality of the cell transfer to the quality of service requirements of the specific broadband ISDN services in order to improve the utilization of the network resources. A description is given of different space priority mechanisms and their performance evaluation. A comparative performance study of these concepts is given, indicating the good performance characteristics of a simple buffering scheme called partial buffer sharing. >

A distributed restoration algorithm for multiple-link and node failures of transport networks

Abstract: Fast restoration of broadband optical fiber networks from multiple-link and node failures, as well as single-link failures, is addressed. A distributed restoration algorithm based on message flooding is described. The algorithm is an extension of a previously proposed algorithm for single-link failure. It restores the network from multiple-link and node failures, using multidestination flooding and path route monitoring. Computer simulation of the algorithm verified that it can find alternate paths within 0.5 s, whenever the message processing delay at a node is 5 ms. >

The ‘leaky bucket’ policing method in the ATM (asynchronous transfer mode) network

Abstract: The new asynchronous transfer mode (ATM) will be used for the information transport in the future broadband network An important function of the ATM network is bandwidth enforcement or policing The so-called ‘leaky bucket’ algorithm can be used to monitor and enforce the bit rate of a constant bit rate (CBR) connection The parameters of the ‘leaky bucket’ algorithm depend on the bit rate of the connection and on the cell delay jitter Sugestions for setting the parameters of the ‘leaky bucket’ algorithm are provided in this paper Furthermore, a ‘dual leaky bucket’ algorithm is proposed to police the traffic parameters of a variable bit rate (VBR) connection The ‘dual leaky bucket’ approach could also be used to define a VBR bearer service in the future broadband network

A self-routing multistage switching network for broadband ISDN

Abstract: A switching network that approaches a maximum throughput of 100% as buffering is increased is proposed. This self-routing switching network consists of simple 2*2 switching elements, distributors, and buffers located between stages and in the output ports. The proposed switching requires a speedup factor of two. The structure and the operation of the switching network are described, and its performance is analyzed. The switch has log/sub 2/N stages that move packets in a store-and-forward fashion, incurring a latency of log/sub 2/N time periods. The performance analysis of the switch under uniform traffic pattern shows that the additional delay is small, and a maximum throughput of 100% is achieved as buffering is increased. >

Wavelength domain optical network techniques

Abstract: Optical network technology will soon allow wavelength-multiplexed optical channels to be carried to multiple terminals, giving rise to new broadband network architectures and protocols. Two stages of evolution are anticipated, with transmission-only structures appearing first and networks with optical switching appearing later. Some basic transmission considerations relating to system operation over wide optical bandwidths for both local and longer distance networks are reviewed, and the present status of experimental optical networks and the components they use are discussed. >

Multichannel wavelength-switched transmitters and receivers-new concepts for broadband networks and distributed switching systems

Abstract: Three component concepts for use in high-density wavelength-division-multiplexed optical systems are described. The applications envisaged for these components include broadband overlay for subscriber access networks and ultrahigh-capacity packet switching for telecommunications or parallel processing computer applications. The components each use a dispersive optical grating and integrated array of optoelectronic transducers to form a component with precisely defined multiple operating wavelength channels. Multichannel laser transmitter and direct detection receiver components suitable for up to about 50 independent channels separated by 1-2 nm in the 1300- to 1600-nm-wavelength range are described. >

Flexible asynchronous transfer mode networks utilizing virtual paths

Abstract: The effect of virtual paths in ATM (asynchronous transfer mode) networks is investigated. The virtual path concept has been proposed as the key technique in enhancing network performance. The impact of the virtual path scheme on transport network architecture and systems is demonstrated in comparison to the digital path scheme in STM-based networks. One of the outstanding virtual path benefits, increased network flexibility, is highlighted. It is shown that dynamic network reconfiguration capability is effectively provided with the virtual path scheme. Some analytical results on the adaptive virtual path bandwidth control effects for multimedia traffic are provided. >

Toward a broadband congestion control strategy

Abstract: The congestion control problem in asynchronous transfer mode (ATM) based broadband networks is defined. In general, a suitable set of congestion controls will include features for admission control, buffer and queue management, traffic enforcement, and reactive control. The leading alternatives for each of these congestion control features are summarized. An approach for choosing the best of these alternatives is presented, and a reasonable set of such alternatives that captures the increased utilization due to statistical multiplexing is suggested. It uses separate and static bandwidth pools for each service category; a statistical multiplexing gain determined for each bandwidth pool that supports a variable-bit-rate (VBR) service category; traffic enforcement on a virtual circuit basis using a leaky bucket algorithm with parameters set to accommodate anticipated levels of cell transfer delay variation; and multilevel loss priorities as well as a reactive control for appropriate VBR service categories based on multithreshold traffic enforcement and explicity congestion notification. >

A 3-stage interconnection structure for very large packet switches

Abstract: Proposes a three-stage broadband packet-switch architecture for a future central office with more than 16000 ports. The switch is constructed by interconnecting many small independent switch modules, which can be implemented using modifications of various well-studied switch fabric designs. Multiple paths are provided for each input-output pair, and the channel grouping technique is used to decrease delay and increase throughput. A datagram packet routing approach is adopted in order to eliminate the table lookup that will be required by virtual-circuit routing. Ways of guaranteeing the sequence integrity of packets are discussed. It is estimated from performance analyses that 32768-port switches can be constructed and can perform well based on switch fabrics of no more than 128 ports. >

A development of a high speed ATM switching LSIC

Abstract: An IC designed for a high-speed broadband ISDN (integrated services digital network) switching system is described. The IC was fabricated using a Bi-CMOS RAM and logic gate array. The IC has functions for cell buffering, switching, and VCI conversion. It features a pipeline configuration and a high-speed ECL (emitter coupled logic) interface for a throughput of 1.2 Gbit/s. Tests confirmed accurate switching and high-speed operation up to 110 MHz, which corresponds to 1.8 Gbit/s throughput. An ATM (asynchronous transfer mode) switching system handling 512 150 Mbit/s channels can be constructed using this IC, and housed in four cabinets. >

System and cost analyses of broad-band fiber loop architectures

Abstract: Analyses of four broadband fiber-optic subscriber loop architectures, including active (high-speed time division multiplexing (TDM)-based) and passive (dense wavelength division multiplexing (WDM)-based, WDM-based with an analog subcarrier-multiplexing overlay, and splitter-based) double-star topologies, are presented. The analyses focus on specific demonstrated architectures and use component cost projections based on learning curves to estimate future network costs on a per-subscriber basis. Also investigated is the sensitivity of projected cost-per-subscriber to remote multiplexing node size and to double-star prove-in distance. The results indicate that the four architectures have very different double-star prove-in distances and that loop costs are minimized for much smaller remote node sizes than active loops, thus permitting cost-effective deployment of passive loops for smaller groups of subscribers. In addition, cost breakdowns for the four architectures indicate that splitter-based passive loops share electronics more effectively among subscribers than loop architectures requiring dedicated (per-subscriber) electronic interfaces, resulting in projected cost advantages for the splitter-based networks. >

Broadband ISDN resource management

Abstract: This paper describes techniques for the management of traffic carrying capacity and control mechanisms in the Broadband ISDN and presents a cost-benefit analysis to determine policies for reserving capacity on virtual paths. Significant savings in total network cost can result from the use of virtual paths.

Use of the 55-65 GHz oxygen absorption band for short-range broadband radio networks with minimal regulatory control

Abstract: The authors describe a new generation of digital radio systems primarily designed for speech and low data rate services, and discuss their use of a broadband radio link. The potential demand and spectral capacity are considered, and factors affecting the frequency plan are outlined. System optimisation is discussed.

Optimal packet discarding: an ATM-oriented analysis model and initial results

Abstract: A problem associated with overload control by packet discarding in integrated packet networks such as a broadband integrated services digital network (B-ISDN) is considered. The question of optimality in priority packet discarding is examined in order to minimize the service degradation associated with the discarding. An analysis model which is consistent with asynchronous transfer mode (ATM) operation of such a network is presented. It is shown how dynamic programming can be used with this model to find an optimal discarding policy, and initial results of such an analysis for queuing systems with a single buffer position are presented. It is shown by example that the optimal policy can perform significantly better over a wide range of parameter values than the default policy of discarding arriving packets only when the queue is full. >

Bandwidth allocation for ATM networks

Abstract: The admission control and bandwidth allocation for ATM (asynchronous transfer mode) networks are studied. A dynamic bandwidth allocation algorithm is proposed and shown to improve the bandwidth equitable accessibility and the overall throughput. The algorithm is evaluated and compared with other allocation algorithms using blocking rate and cell throughput as evaluation criteria. An on-going study of the user-controlled bandwidth variation is also briefly described. It is shown that as more calls intend to crossover from a lower bandwidth destination to a higher one, the network suffers from a higher connection blocking. >

Information Superhighways: The Economics of Advanced Public Communication Networks

Abstract: Future communications technology a new paradigm economics of broadband networks regulation and institutional considerations stakeholder analysis supplier analysis broadband network costs capital budgeting for universal broadband networks capital recovery prosensus public policy and technology conflict.

Low-cost digital passive optical networks

Abstract: Techniques for reducing the cost of providing digital telephony and broadband services to the home over passive optical networks are proposed. These include the use of optical transceivers in an optical TDMA (time-division multiple access) telephony system and using low-cost consumer technology in providing a digital CATV (cable television) service using TDM (time division multiplexing). >

Trends in multimedia applications and the network models to support them

Abstract: Leading corporations and federal agencies are beginning to recognize the great potential of multimedia applications. IBM and Apple have announced major commitments to develop equipment and software for multimedia applications. Current trends in multimedia applications are examined. A summary of the network implications in view of broadband ISDN (B-ISDN) is included. Multimedia database systems; audio, video, and graphics multimedia mail; teleconferencing; video extension to the X window (VEX); and an audio server under development at Olivetti Research Center (VOX) are outlined. Handling multimedia requests, distributed computing and shared resources, media conversion, and issues of network design are discussed. >

Integration of CAD/CAE with multimedia teleconferencing and messaging via broadband networks and shared resource servers

Abstract: It is noted that, if multimedia electronic meeting and messaging systems were tightly integrated with networked CAE/CAD (computer-aided engineering and design) resources, great value could be added to modern design projects. Work in Bellcore's Integrated Media Architecture Laboratory (IMAL) relevant to these and other related capabilities is described. A working premises-based network with shared CAD/CAE systems, conferencing, and messaging servers, encompassing video, graphics, text and audio, has been constructed as part of the Bellcore IMAL project. The example IMAL network can be duplicated with off-the-shelf products and can be extended to link multiple premise locations through the use of commonly available DS-3 codecs and telephone-company-provided DS-3 fibers. >

Performance characterizations of traffic monitoring, and associated control, mechanisms for broadband 'packet' networks

Abstract: A number of performance issues associated with real-time traffic-monitoring schemes are addressed. These schemes will likely be used in broadband packet-transport-based networks such as broadband ISDN (B-ISDN) with asynchronous transfer mode (ATM). The issues of an appropriate performance framework for traffic-monitoring scheme comparisons, appropriate control actions based on traffic-monitoring, and how traffic parameters (that could enter strongly into service contracts between the network and users) should best be specified are treated in an overview summary. Some of the more commonly suggested traffic-monitoring schemes are described, and the leaky-bucket scheme is analyzed. A relationship between traffic peakedness and traffic-monitoring schemes is introduced. >

ATMR: ring architecture for broadband networks

Abstract: A shared-medium networking approach based on an asynchronous transfer mode ring (ATMR) scheme is proposed for constructing broadband networks such as high-speed local area networks, metropolitan area networks, and access networks for broadband integrated services digital networks (B-ISDNs). The ATMR, providing distributed ATM (asynchronous transfer mode) switching capability throughout a ring network topology, consists primarily of counter-rotating dual slotted rings. The functional requirements for broadband access networks are discussed, followed by a description of ATMR technical features, including protocols, networking, and access node system architecture. Laboratory prototypes of the ATMR hardware architecture have been designed to confirm the feasibility of its protocol and system architectural concepts. A prototype ATMR protocol function, having a 156-Mb/s cell stream and a minimum cell header processing delay, was fabricated on a ring access control LSI chip using BiCMOS LSI technology. >

Survey of traffic control protocols in ATM networks

Abstract: Among the techniques proposed to implement broadband ISDN (B-ISDN), asynchronous transfer mode (ATM) is considered to be the most promising transfer technique because of its efficiency and flexibility. Traffic control protocols in ATM networks are surveyed. The topics covered include congestion control and priority schemes to support multiple classes of traffic in ATM networks. Various preventive control schemes proposed for ATM networks are examined. Among them are admission control and bandwidth enforcement mechanisms, and, in particular, the leaky bucket method. Two priority schemes, a scheduling method and a local congestion control scheme, are discussed. >

A framework for a national broadband (ATM/B-ISDN) network

Abstract: The authors propose a hybrid packet- and circuit-switched network as a framework for a national broadband (ATM/B-ISDN) (asynchronous transfer mode/broadband-integrated services digital network). Built on the observation that transmission speeds are likely to remain much faster than switching speeds (thus packet switching at peak transmission rates needs to be avoided), the network architecture is a three-tier hierarchy composed of LANs (local area networks), network nodes and DACS (digital access and cross-connect systems). Access to the network is either through direct connection to a DACS or network node, or through the end-user's LAN, which has a gateway to a network node. Each network node is a high-performance ATM packet switch, which accepts input cells at a B-ISDN rate of 150 Mb/s and serves both as LAN-to-LAN interconnect and as a packet concentrator for traffic destined to other network nodes and LANs. To minimize the delay and simplify the implementation of gigabit-per-second packet switching, the network nodes are interconnected by a backbone network of multi-gigabit-per-second fibers and DACS, which provide reconfigurable circuits between network nodes. A congestion control technique using channel sharing that dramatically reduces the required buffer size is proposed. >